DISPLAY DEVICE AND ELECTRONIC DEVICE
A novel display device capable of adjusting color purity is provided. A novel display device with improved adhesion of a color filter is provided. A novel display device capable of excellent reflective display is provided. The display device includes a transistor, a reflective electrode layer formed on the same surface as a source electrode layer or a drain electrode layer of the transistor, a first insulating layer over the reflective electrode layer, a coloring layer which is over the first insulating layer and overlaps with the reflective electrode layer, a second insulating layer over the coloring layer, and a pixel electrode layer over the second insulating layer. The coloring layer includes at least a first opening and a second opening. The pixel electrode layer is electrically connected to the transistor through the first opening. The second insulating layer is in contact with the first insulating layer in the second opening.
1. Field of the Invention
The present invention relates to an object, a method, or a manufacturing method. In addition, the present invention relates to a process, a machine, manufacture, or a composition of matter. One embodiment of the present invention relates to a semiconductor device, a display device, an electronic device, a manufacturing method thereof, or a driving method thereof. One embodiment of the present invention particularly relates to, for example, a reflective liquid crystal display device.
Note that the term “display device” means a device including a display element. In addition, the display device includes a driver circuit for driving a plurality of pixels, and the like. Furthermore, the display device may include a control circuit, a power supply circuit, a signal generation circuit, or the like formed over another substrate.
2. Description of the Related Art
With the recent rapid spread of portable information terminals such as smartphones, improvement in their performance has progressed rapidly. Their screens have been increased in size and resolution, and some recent ones have resolutions as high as over 300 ppi.
For example, liquid crystal display devices generally have a structure in which R, G, and B sub-pixels are provided in a display region and provided with their respective color filters. The color filters are provided over a substrate (a counter substrate) which faces an active-matrix substrate (a substrate provided with elements (e.g., transistors) for driving pixels).
With the increase in resolution, the alignment accuracy between an active-matrix substrate and a counter substrate provided with color filters can be recognized as a problem. In view of this problem, attention has been focused on what is called a color filter on array (COA) structure, in which a color filter is formed on the active-matrix substrate side.
As a liquid crystal display device with a COA structure, a reflective or semi-transmissive liquid crystal display device which includes a color filter, a pixel electrode, and a reflective layer on the active-matrix substrate side and in which light entering from the counter substrate side is transmitted through the pixel electrode and the color filter and is reflected by the underlying reflective layer and is visually recognized is disclosed (e.g., see Patent Document 1 and Patent Document 2).
PATENT DOCUMENTS [Patent Document 1] Japanese Published Patent Application No. 2000-187209 [Patent Document 2] PCT International Publication No. 2011/045953 SUMMARY OF THE INVENTIONIn the case of a reflective display device in which a counter substrate is provided with a color filter, light such as external light is transmitted through the color filter, reflected by a reflective film or the like, and transmitted through the color filter again.
Also in the case of a reflective display device having a COA structure, light such as external light is transmitted through the color filter, reflected by a reflective film or the like, and transmitted through the color filter again. That is, light such as external light is transmitted through the color filter twice and is then observed by a viewer. This may increase the color purity of reflected light. In the case where external light is relatively weak in a room or the like, reflected light with high color purity is weak, resulting in dark display.
The color purity of reflected light in a reflective display device can be adjusted by the thickness of a color filter, for example. The color purity can be adjusted also by changing a coloring material, such as a pigment, which is used for the color filter. However, when the thickness of the color filter is large or small, it is difficult to make the thickness uniform all over a substrate surface. In the case where a coloring material used for the color filter is changed, the material change results in increases in development time and cost.
Another problem is low adhesion between the color filter and a surface over which the color filter is formed. For example, as the color filter, a photosensitive resin film is formed by applying and drying a photosensitive resin solution in which a coloring material is dispersed. Since the coloring material is dispersed, light intensity at the time of light exposure of the photosensitive resin film decreases in a depth direction, which may cause insufficient photocuring and low adhesion at or around the interface between the photosensitive resin film and the surface over which the photosensitive resin film is formed.
In view of the above problems, an object of one embodiment of the present invention is to provide a novel display device capable of adjusting color purity. Another object of one embodiment of the present invention is to provide a novel display device with improved adhesion of a color filter. Another object of one embodiment of the present invention is to provide a novel display device of which productivity is improved. Another object of one embodiment of the present invention is to provide a novel display device capable of excellent reflective display. Another object of one embodiment of the present invention is to provide a novel display device with a COA structure that is capable of excellent reflective display. Another object of one embodiment of the present invention is to provide a novel display device or the like.
Note that the descriptions of these objects do not disturb the existence of other objects. Note that in one embodiment of the present invention, there is no need to achieve all the objects. Note that other objects will be apparent from the description of the specification, the drawings, the claims, and the like and other objects can be derived from the description of the specification, the drawings, the claims, and the like.
One embodiment of the present invention is a display device which includes a pixel region, a transistor formed in the pixel region, a source electrode layer or a drain electrode layer of the transistor, an insulating layer over the source electrode layer or the drain electrode layer, a pixel electrode layer over the insulating layer, and a coloring layer overlapping with the pixel electrode layer and the drain electrode layer. The pixel electrode layer is electrically connected to the transistor. The coloring layer includes at least a first opening and a second opening.
In the above embodiment, the coloring layer may be formed over a counter substrate, and a substrate provided with the pixel electrode layer and the counter substrate may be aligned with and attached to each other such that the coloring layer overlaps with the pixel electrode layer. In the above embodiment, the pixel electrode layer may function as a reflective electrode layer.
In the above embodiment, the coloring layer may be a material layer capable of transmitting light in a red wavelength range, a material layer capable of transmitting light in a green wavelength range, or a material layer capable of transmitting light in a blue wavelength range. As another color of the coloring layer, cyan, magenta, yellow, or the like may be used. In the case where three or more kinds of coloring layers are used to achieve full-color display, each coloring layer may have an upper surface shape different from those of the coloring layers of the other colors, and for example, may have a different opening shape. A plurality of coloring layers are not necessarily formed over one substrate, and for example, the counter substrate may be provided with a first coloring layer and the substrate provided with the transistor may be provided with a second coloring layer and a third coloring layer.
In the above embodiment, the display device may further include a second coloring layer and a third coloring layer. The second coloring layer includes at least a third opening and a fourth opening. Upper surface shapes of the third opening and the fourth opening are different from those of the first opening and the second opening. When an opening in a red coloring layer has a larger area than that of an opening in a blue coloring layer, reflectance can be improved with an NTSC ratio maintained.
Another embodiment of the present invention is a display device which includes a pixel region, a transistor formed in the pixel region, a reflective electrode layer formed on the same surface as a source electrode layer or a drain electrode layer of the transistor, a first insulating layer over the reflective electrode layer, a coloring layer which is over the first insulating layer and overlaps with the reflective electrode layer, a second insulating layer over the coloring layer, and a pixel electrode layer over the second insulating layer. The coloring layer includes at least a first opening and a second opening. The pixel electrode layer is electrically connected to the transistor through the first opening. The second insulating layer is in contact with the first insulating layer in the second opening.
Another embodiment of the present invention is a display device which includes a pixel region, a transistor formed in the pixel region, a reflective electrode layer formed on the same surface as a source electrode layer or a drain electrode layer of the transistor, a first insulating layer including an inorganic insulating material over the reflective electrode layer, a coloring layer which is over the first insulating layer and overlaps with the reflective electrode layer, a second insulating layer including an organic insulating material over the coloring layer, and a pixel electrode layer over the second insulating layer. The coloring layer includes at least a first opening and a second opening. The pixel electrode layer is electrically connected to the transistor through the first opening. The second insulating layer is in contact with the first insulating layer in the second opening.
In each of the above embodiments, it is preferable that the transistor include a gate electrode layer, a gate insulating layer over the gate electrode layer, a semiconductor layer over the gate insulating layer, and the source electrode layer and the drain electrode layer which are in contact with the gate insulating layer and the semiconductor layer.
In each of the above embodiments, it is preferable that the first insulating layer include a third opening overlapping with the first opening and the pixel electrode layer be electrically connected to the drain electrode layer of the transistor through the first opening and the third opening.
In each of the above embodiments, it is preferable that the semiconductor layer be an oxide semiconductor layer. The oxide semiconductor layer preferably includes an oxide represented by an In-M-Zn oxide that contains at least indium (In), zinc (Zn), and M (M represents Al, Ga, Ge, Y, Zr, Sn, La, Ce, or Hf).
In each of the above embodiments, a touch panel may overlap with the pixel region, or the counter substrate may be provided with a circuit having a touch input function.
Embodiments of the present invention also include an electronic device including the above display device.
In one embodiment of the present invention, a novel display device capable of adjusting color purity can be provided. In one embodiment of the present invention, a novel display device with improved adhesion of a color filter can be provided. Furthermore, in one embodiment of the present invention, a novel display device of which productivity is improved can be provided. Furthermore, in one embodiment of the present invention, a novel display device capable of excellent reflective display can be provided. Furthermore, in one embodiment of the present invention, a novel display device or the like can be provided.
Note that the descriptions of these effects do not disturb the existence of other effects. Note that in one embodiment of the present invention, there is no need to achieve all the effects. Note that other effects will be apparent from the description of the specification, the drawings, the claims, and the like and other effects can be derived from the description of the specification, the drawings, the claims, and the like.
In the accompanying drawings:
Embodiments will be hereinafter described with reference to drawings. However, the embodiments can be implemented with various modes. It will be readily appreciated by those skilled in the art that modes and details can be changed in various ways without departing from the spirit and scope of the present invention. Therefore, the present invention should not be construed as being limited to the description in the following embodiments.
In drawings, the size, the layer thickness, or the region is exaggerated for clarity in some cases. Therefore, embodiments of the present invention are not limited to such a scale. Note that drawings are schematic views showing ideal examples, and embodiments of the present invention are not limited to shapes or values shown in the drawings.
Ordinal numbers such as “first”, “second”, and “third” in this specification are used in order to avoid confusion among components, and the terms do not limit the components numerically.
Note that in this specification, terms for describing arrangement, such as “over” and “under”, are used for convenience for describing the positional relation between components with reference to drawings. Further, the positional relation between components is changed as appropriate in accordance with a direction in which each component is described. Thus, the positional relation is not limited to that described with a term used in this specification and can be explained with another term as appropriate depending on the situation.
In this specification and the like, a transistor is an element having at least three terminals of a gate, a drain, and a source. In addition, the transistor has a channel region between a drain (a drain terminal, a drain region, or a drain electrode layer) and a source (a source terminal, a source region, or a source electrode layer), and current can flow through the drain, the channel region, and the source.
Functions of a “source” and a “drain” are sometimes replaced with each other when a transistor of opposite polarity is used or when the direction of current flowing is changed in circuit operation, for example. Therefore, the terms “source” and “drain” can be replaced with each other in this specification and the like.
In this specification and the like, the term “electrically connected” includes the case where components are connected through an object having any electric function. There is no particular limitation on an “object having any electric function” as long as electric signals can be transmitted and received between components that are connected through the object. Examples of an “object having any electric function” include a switching element such as a transistor, a resistor, an inductor, a capacitor, and an element with a variety of functions, as well as an electrode and a wiring.
In this specification and the like, a pixel region includes at least a pixel (corresponding to a display unit that can control the luminance of one color element (e.g., any one of R (red), G (green), and B (blue))). Therefore, in a color display device, the minimum display unit of a color image is composed of three pixels of an R pixel, a G pixel, and a B pixel. Note that the colors of the color elements for displaying color images are not limited to three colors, and may be more than three colors or may include a color other than R, G, and B. For example, a display unit may be composed of four pixels of the R pixel, the G pixel, the B pixel, and a W (white) pixel. Alternatively, a display unit may be composed of a plurality of color elements among R, G, and B as in PenTile layout.
Embodiment 1In this embodiment, a display device of one embodiment of the present invention will be described with reference to
In
Furthermore, a conductive layer 104b that is formed in the same step as the conductive layer 104a serving as a gate electrode layer and the conductive layer 110b_2 that serves as a drain electrode layer are stacked with an insulating layer that is formed in the same step as the gate insulating layer positioned therebetween. The conductive layer 104b, the insulating layer that is formed in the same step as the gate insulating layer, and the conductive layer 110b_2 form a capacitor 152.
The transistor 150 is electrically connected to a pixel electrode layer 118. Specifically, the pixel electrode layer 118 is electrically connected to the conductive layer 110b_2 that serves as the drain electrode layer of the transistor 150, through an opening 134 and an opening 138.
It is preferable that the area of a region where the source line 110 including the conductive layer 110b_1 and the gate line 104 including the conductive layer 104a intersect with each other be small as illustrated in
The pixel region 120 includes a conductive layer 110b_3 that is formed in the same step as the conductive layer 110b_1 serving as the source electrode layer of the transistor 150 and the conductive layer 110b_2 serving as the drain electrode layer of the transistor 150. Note that the conductive layer 110b_3 has a function of a reflective electrode layer. The conductive layer 110b_3 overlaps with a coloring layer 114. The coloring layer 114 overlaps with the pixel electrode layer 118.
In the structure in
The coloring layer 114 has an opening 134 serving as a first opening and an opening 136 serving as a second opening. Note that
The opening 134 serves as an opening for connection between the transistor 150 and the pixel electrode layer 118. The opening 136 has a function of adjusting the color purity of the coloring layer 114. In other words, the color purity of the coloring layer 114 can be adjusted with the shape or number of openings 136.
Such a structure in which the coloring layer 114 has the opening 136 makes it easy to adjust the color purity of the coloring layer 114.
Here, an upper surface shape of the coloring layer 114 in the display device illustrated in
The coloring layer 114 illustrated in
Note that
The coloring layer 114 in
Note that the shape and arrangement of the coloring layer 114, the opening 134, the openings 136, and the like may be changed depending on the color of the pixel. For example, the structure in
Alternatively, a transmissive region 401 may be provided in one pixel. Alternatively, a semi-transmissive display device including the transmissive region 401 and a reflective region 400 may be formed.
Next, cross sections of the display device illustrated in
The display device in
Note that the conductive layer 104a, the insulating layers 106a and 106b, the semiconductor layer 108, and the conductive layers 110a_1, 110a 2, 110b_1, and 110b_2 form the transistor 150. The conductive layer 104b, the insulating layers 106a and 106b, and the conductive layers 110a_3 and 110b_3 form the capacitor 152.
Note that a portion of the insulating layers 106a and 106b which overlaps with the conductive layer 104a serving as a gate electrode layer has a function of a gate insulating layer of the transistor 150, and a portion thereof which overlaps with the conductive layer 104b has a function of a dielectric layer of the capacitor 152.
The insulating layers 106a and 106b are provided with an opening 132 which reaches the conductive layer 104b, and the conductive layers 110a_2 and 110b_2 having a function of a drain electrode layer of the transistor 150 are connected to the conductive layer 104b through the opening 132.
Note that the example in which the opening 132 is provided is described here; however, one embodiment of the present invention is not limited to this example. For example, a structure in which the opening is not provided as illustrated in
The coloring layer 114 is provided with the opening 134 and the openings 136. In other words, the insulating layer 116 over the coloring layer 114 is in contact with the insulating layer 112 in the opening 134. Note that the adhesion of the insulating layer 116 to the insulating layer 112 is higher than that of the coloring layer 114. Therefore, when there is a region where the insulating layer 116 and the insulating layer 112 are in contact with each other, separation of the coloring layer 114 can be suppressed even in the case where the adhesion between the coloring layer 114 and the insulating layer 112 is not sufficient.
The insulating layer 112 is preferably formed with an inorganic insulating material. The insulating layer 116 is preferably formed with an organic insulating material. When the insulating layer 112 is formed with an inorganic insulating material, the insulating layer 112 can have favorable characteristics of the interface with the semiconductor layer 108. When the insulating layer 116 is formed with an organic insulating material, the pixel electrode layer 118 formed over the insulating layer 116 can have high flatness.
The color purity of the coloring layer 114 can be adjusted with the openings 136 provided in the coloring layer 114. For example, the color purity of the coloring layer 114 can be adjusted by adjusting the shape of the openings 136 or the area of the openings 136.
With such a structure in which the coloring layer 114 has the openings 136, a novel display device capable of adjusting color purity can be provided. It addition, a novel display device with improved adhesion of the coloring layer 114 used as a color filter can be provided.
The insulating layer 112 is provided with the opening 138. The pixel electrode layer 118 is connected to the conductive layer 110c_1 serving as a drain electrode layer of the transistor 150, through the openings 134 and 138.
The conductive layer 110b_3 has a function of a reflective electrode layer. Therefore, a highly reflective conductive layer is preferably used. For example, the highly reflective conductive layer is formed to have a single-layer structure or a stacked-layer structure including any of metals such as aluminum, silver, palladium, and copper or an alloy containing any of these metals as its main component. It is particularly preferable to use a material including aluminum for the conductive layer 110b_3 in terms of cost, processability, and the like. As the conductive layer 110c_1, it is preferable to use a highly oxidation-resistant conductive layer. When a highly oxidation-resistant conductive layer is used as the conductive layer 110c_1, its contact resistance with the pixel electrode layer 118 can be decreased. This can increase reflectance and decrease contact resistance with the pixel electrode layer.
In other words, in the display device illustrated in
Note that the transmissive region 401 may be provided as illustrated in
In the display device in
The conductive layer 164 is formed under the second substrate 162. The pixel electrode layer 118, the liquid crystal layer 166, and the conductive layer 164 form a liquid crystal element 170. By application of voltage between the pixel electrode layer 118 and the conductive layer 164, the alignment state in the liquid crystal layer 166 can be controlled. In
In the display device in
Note that the transistor 150 may be provided with a gate electrode over a channel or under the channel, or may be provided with gate electrodes over and under the channel.
Note that as illustrated in
Note that a conductive layer 199c may be provided as a conductive layer which is formed at the same time as the conductive layer 199a through the same film formation step and the same etching step. The conductive layer 199c may be provided in a portion for connection to the pixel electrode layer 118.
Next, the display device illustrated in
The display device in
When the coloring layers 114a and 114b are formed over the coloring layer 114 as illustrated in
With such a structure in which coloring layers are stacked in a region other than at least a reflective region, i.e., a structure in which a coloring layer overlaps with a coloring layer of an adjacent pixel, part of the coloring layers can function as a black matrix.
Note that other components of the display device in
A method for manufacturing the display device illustrated in
First, the first substrate 102 is prepared. For the first substrate 102, a glass material such as aluminosilicate glass, aluminoborosilicate glass, or barium borosilicate glass is used. In the mass production, for the first substrate 102, a mother glass with any of the following sizes is preferably used: the 8th generation (2160 mm×2460 mm), the 9th generation (2400 mm×2800 mm, or 2450 mm×3050 mm), the 10th generation (2950 mm×3400 mm), and the like. High process temperature and a long period of process time drastically shrink the mother glass. Thus, in the case where mass production is performed with the use of the mother glass, the heating temperature in the manufacturing process is preferably 600° C. or lower, further preferably 450° C. or lower, still further preferably 350° C. or lower.
Then, a conductive layer is formed over the first substrate 102 and processed into desired shapes, so that the conductive layers 104a and 104b are formed (see
For the conductive layers 104a and 104b, a metal element selected from aluminum, chromium, copper, tantalum, titanium, molybdenum, and tungsten, an alloy containing any of these metal elements as a component, an alloy containing these metal elements in combination, or the like can be used. In addition, the conductive layers 104a and 104b may have a single-layer structure or a stacked-layer structure of two or more layers. For example, a two-layer structure in which a titanium film is stacked over an aluminum film, a two-layer structure in which a titanium film is stacked over a titanium nitride film, a two-layer structure in which a tungsten film is stacked over a titanium nitride film, a two-layer structure in which a tungsten film is stacked over a tantalum nitride film or a tungsten nitride film, a three-layer structure in which a titanium film, an aluminum film, and a titanium film are stacked in this order, and the like can be given. Alternatively, an alloy film or a nitride film in which aluminum and one or more elements selected from titanium, tantalum, tungsten, molybdenum, chromium, neodymium, and scandium are contained may be used. The conductive layers 104a and 104b can be formed by a sputtering method, for example.
Next, the insulating layers 106a and 106b are formed over the first substrate 102 and the conductive layers 104a and 104b (see
The insulating layer 106a is formed to have a single-layer structure or a stacked-layer structure using, for example, any of a silicon nitride oxide film, a silicon nitride film, an aluminum oxide film, and the like with a PE-CVD apparatus. In the case where the insulating layer 106a has a stacked-layer structure, it is preferable that a silicon nitride film with fewer defects be provided as a first silicon nitride film, and a silicon nitride film from which hydrogen and ammonia are less likely to be released be provided over the first silicon nitride film, as a second silicon nitride film. As a result, hydrogen and nitrogen contained in the insulating layer 106a can be prevented from moving or diffusing into the semiconductor layer 108 formed later.
The insulating layer 106b is formed to have a single-layer structure or a stacked-layer structure using any of a silicon oxide film, a silicon oxynitride film, and the like with a PE-CVD apparatus.
As for the insulating layers 106a and 106b, for example, a 400-nm-thick silicon nitride film can be formed as the insulating layer 106a, and then a 50-nm-thick silicon oxynitride film can be formed as the insulating layer 106b. The silicon nitride film and the silicon oxynitride film are preferably formed in succession in a vacuum such that fewer impurities are mixed into the films. Note that portions of the insulating layers 106a and 106b overlapping with the conductive layer 104a serve as the gate insulating layer of the transistor 150. In addition, portions of the insulating layers 106a and 106b overlapping with the conductive layer 104b serve as a dielectric layer of the capacitor 152.
Note that silicon nitride oxide refers to an insulating material that contains more nitrogen than oxygen, whereas silicon oxynitride refers to an insulating material that contains more oxygen than nitrogen.
When the gate insulating layer has the above structure, the following effects can be obtained, for example. The silicon nitride film has a higher relative permittivity than a silicon oxide film and needs a larger thickness for an equivalent capacitance. Thus, the physical thickness of the gate insulating layer can be increased. This makes it possible to reduce a decrease in the withstand voltage of the transistor 150 and furthermore increase the withstand voltage, thereby preventing electrostatic breakdown of the transistor 150.
Next, a semiconductor layer is formed over the insulating layer 106b and processed into a desired shape, so that the semiconductor layer 108 is formed. Note that the semiconductor layer 108 is formed in a position overlapping with the conductive layer 104a (see
For the semiconductor layer 108, amorphous silicon, polycrystalline silicon, single crystal silicon, or the like can be used, for example. It is particularly preferable to use an oxide semiconductor for the semiconductor layer 108. The oxide semiconductor preferably includes an oxide represented by an In-M-Zn oxide that contains at least indium (In), zinc (Zn), and M (M represents Al, Ga, Ge, Y, Zr, Sn, La, Ce, or Hf). Alternatively, both In and Zn are preferably contained.
As the oxide semiconductor, for example, any of the following can be used: indium oxide, tin oxide, zinc oxide, an In—Zn oxide, a Sn—Zn oxide, an Al—Zn oxide, a Zn—Mg oxide, a Sn—Mg oxide, an In—Mg oxide, an In—Ga oxide, an In—Ga—Zn oxide, an In—Al—Zn oxide, an In—Sn—Zn oxide, a Sn—Ga—Zn oxide, an Al—Ga—Zn oxide, a Sn—Al—Zn oxide, an In—Hf—Zn oxide, an In—La—Zn oxide, an In—Ce—Zn oxide, an In—Pr—Zn oxide, an In—Nd—Zn oxide, an In—Sm—Zn oxide, an In—Eu—Zn oxide, an In—Gd—Zn oxide, an In—Tb—Zn oxide, an In—Dy—Zn oxide, an In—Ho—Zn oxide, an In—Er—Zn oxide, an In—Tm—Zn oxide, an In—Yb—Zn oxide, an In—Lu—Zn oxide, an In—Sn—Ga—Zn oxide, an In—Hf—Ga—Zn oxide, an In—Al—Ga—Zn oxide, an In—Sn—Al—Zn oxide, an In—Sn—Hf—Zn oxide, or an In—Hf—Al—Zn oxide.
Note that, for example, an In—Ga—Zn oxide means an oxide containing In, Ga, and Zn as its main components and there is no particular limitation on the ratio of In to Ga and Zn. The In—Ga—Zn oxide may contain another metal element in addition to In, Ga, and Zn. In this embodiment, an oxide semiconductor is used for the semiconductor layer 108.
Next, first heat treatment is preferably performed. The first heat treatment may be performed at a temperature higher than or equal to 250° C. and lower than or equal to 650° C., preferably higher than or equal to 300° C. and lower than or equal to 500° C., in an inert gas atmosphere, an atmosphere containing an oxidizing gas at 10 ppm or more, or a reduced pressure state. Alternatively, the first heat treatment may be performed in such a manner that heat treatment is performed in an inert gas atmosphere, and then another heat treatment is performed in an atmosphere containing an oxidizing gas at 10 ppm or more, in order to compensate for desorbed oxygen. By the first heat treatment, the crystallinity of the oxide semiconductor that is used for the semiconductor layer 108 can be improved, and in addition, impurities such as hydrogen and water can be removed from the insulating layers 106a and 106b and the semiconductor layer 108. The first heat treatment may be performed before processing into the semiconductor layer 108 having an island shape.
Next, the opening 132 is formed in a desired region of the insulating layers 106a and 106b (see
Note that the opening 132 is formed so as to reach the conductive layer 104b. The opening 132 can be formed by, for example, wet etching, dry etching, or a combination of wet etching and dry etching.
Next, a conductive layer 109a, a conductive layer 109b, and a conductive layer 109c are formed over the insulating layer 106b and the semiconductor layer 108 so as to cover the opening 132 (see
The conductive layer 109a serves as a barrier metal. The conductive layer 109a can be formed using any material that provides excellent contact resistance between the conductive layer 109a and the semiconductor layer 108. For example, the conductive layer 109a is formed to have a single-layer structure or a stacked-layer structure including any of metals such as titanium, chromium, nickel, yttrium, zirconium, molybdenum, tantalum, and tungsten or an alloy containing any of these metals as its main component.
The conductive layer 109b, which is to serve as part of a reflective electrode layer, is preferably formed using a conductive material with high reflectivity. Further, the conductive layer 109b serves as part of the source electrode layer and part of the drain electrode layer of the transistor, and therefore is preferably formed using a low-resistance material. For example, the conductive layer 109b is formed to have a single-layer structure or a stacked-layer structure including any of metals such as aluminum, silver, palladium, and copper or an alloy containing any of these metals as its main component. It is particularly preferable to use a material including aluminum for the conductive layer 109b in terms of cost, processability, and the like.
The conductive layer 109c can be formed using any material that provides excellent contact resistance between the conductive layer 109c and the pixel electrode layer 118 connected later, and a highly oxidation-resistant conductive layer can be used. Note that the oxidation resistance of the highly oxidation-resistant conductive layer is higher than at least that of a material used for the conductive layer 109b. For example, the conductive layer 109c is formed to have a single-layer structure or a stacked-layer structure including any of metals such as titanium, chromium, nickel, yttrium, molybdenum, tantalum, and tungsten, an alloy containing any of these metals as its main component, or a metal nitride containing any of these materials as its main component. It is particularly preferable to use a material including titanium or molybdenum for the conductive layer 109c, in which case excellent contact resistance between the conductive layer 109c and a material (e.g., indium tin oxide (ITO)) used for the pixel electrode layer 118 can be provided.
For example, a titanium film or a titanium nitride film is used as the conductive layer 109a, an aluminum film or a silver film is used as the conductive layer 109b, and a titanium film or a titanium nitride film is used as the conductive layer 109c. Alternatively, a molybdenum film or a molybdenum nitride film is used as the conductive layer 109a, an aluminum film or a silver film is used as the conductive layer 109b, and a molybdenum film or a molybdenum nitride film is used as the conductive layer 109c.
Note that the structures of the conductive layers 109a, 109b, and 109c are not limited to the above, and a two-layer structure without the conductive layer 109a may be employed. An example of the two-layer structure is a structure in which an aluminum film is used as the conductive layer 109b and a titanium film is used as the conductive layer 109c.
The conductive layers 109a, 109b, and 109c can be formed by a sputtering method, for example.
Then, the conductive layer 109c is processed into a desired shape, so that the conductive layer 110c_1 is formed (see
The conductive layer 110_1 is formed at least in a region to be in contact with the pixel electrode layer 118 later. A conductive layer different from the conductive layer 110c_1 may be formed in the same step as the conductive layer 110c_1. An example of the conductive layer formed in the same step as the conductive layer 110c_1 is a conductive layer formed over a connection portion or an FPC terminal portion.
Note that when the conductive layer 110c_1 is formed, at least a portion of a surface of the conductive layer 109b is exposed. A region of the conductive layer 109b where the surface is exposed serves as a reflective electrode layer later. Examples of a method for forming the conductive layer 110c_1 include a dry etching method, a wet etching method, and plasma treatment. When the conductive layer 110c_1 is formed, the surface of the conductive layer 109b may become uneven. The uneven surface can diffusely reflect incident light. This is preferable when the conductive layer 109b is used as the reflective electrode layer because the reflective electrode layer can have improved reflection efficiency.
Then, the conductive layers 109a and 109b are processed into desired shapes, so that the conductive layers 110a_1, 110b_1, 110a_2, and 110b_2, which serve as the source electrode layer and the drain electrode layer of the transistor 150, and the conductive layers 110a_3 and 110b_3, which serve as the reflective electrode layer and one electrode of the capacitor 152, are formed. At this stage, the transistor 150 and the capacitor 152 are formed (see
The conductive layers 110a_1, 110b_1, 110a_2, 110b_2, 110a_3, and 110b_3 are formed in such a manner that a mask is formed over the conductive layers 109a and 109b and regions not covered with the mask are etched. As an etching method for forming the conductive layers 110a_1, 110b_1, 110a_2, 110b_2, 110a_3, and 110b_3, a dry etching method or a wet etching method can be used.
When the conductive layers 110a_1, 110b_1, 110a_2, 110b_2, 110a_3, and 110b_3 are formed, the semiconductor layer 108 may be partly etched to have a depressed portion.
Note that the cross-sectional structure illustrated in
Next, the insulating layer 112 is formed over the semiconductor layer 108, the conductive layers 110b_1, 110b_2, 110b_3, and 110c_1, and the insulating layer 106b (see
For the insulating layer 112, an inorganic insulating material containing oxygen can be used in order to improve the characteristics of the interface with the oxide semiconductor used for the semiconductor layer 108. The insulating layer 112 can be formed by a PE-CVD method, for example.
As an example of the insulating layer 112, a silicon oxide film, a silicon oxynitride film, an aluminum oxide film, or the like having a thickness of greater than or equal to 50 nm and less than or equal to 500 nm can be used. In this embodiment, a 450-nm-thick silicon oxynitride film is used as the insulating layer 112.
Another insulating layer may be formed over the insulating layer 112. The insulating layer is formed using a material that can prevent an external impurity such as water, an alkali metal, or an alkaline earth metal from diffusing into the oxide semiconductor used for the semiconductor layer 108. For example, a silicon nitride film a silicon nitride oxide film, or the like having a thickness of greater than or equal to 50 nm and less than or equal to 500 nm can be used as the insulating layer.
The insulating layer 112 over the conductive layer 110b_3 serving as a reflective electrode layer is preferably thin. For example, the thickness of the insulating layer 112 over the conductive layer 110b_3 is preferably greater than or equal to 1 nm and less than or equal to 100 nm, further preferably greater than or equal to 5 nm and less than or equal to 50 nm. Forming the insulating layer 112 thin over the conductive layer 110b_3 can shorten the optical path length between the conductive layer 110b_3 and the coloring layer 114. For example, the insulating layer 112 over the conductive layer 110b_3 serving as a reflective electrode layer is thinned in such a manner that, after the formation of the insulating layer 112, a mask is formed in a region other than the conductive layer 110b_3 and the insulating layer 112 over the conductive layer 110b_3 is etched.
Next, the coloring layer 114 having a desired shape is formed over the insulating layer 112. Then, the insulating layer 116 is formed so as to cover the coloring layer 114 (see
The coloring layer 114 is a coloring layer having a function of transmitting light in a particular wavelength region. For example, a red (R) color filter for transmitting light in a red wavelength range, a green (G) color filter for transmitting light in a green wavelength range, a blue (B) color filter for transmitting light in a blue wavelength range, or the like can be used. Each color filter is formed in a desired position with any of various materials by a printing method, an inkjet method, an etching method using a photolithography technique, or the like.
Note that the coloring layer 114 has the opening 134 serving as a first opening and the opening 136 serving as a second opening.
For the insulating layer 116, an organic insulating material such as an acrylic resin can be used. With the insulating layer 116, an impurity or the like contained in the coloring layer 114 can be prevented from diffusing to the liquid crystal layer 166 side, for example. Moreover, the insulating layer 116 can planarize unevenness and the like due to the transistor 150 or the coloring layer 114.
Note that the insulating layer 116 preferably has an opening in substantially the same position as the opening 134 in the coloring layer 114. The opening is formed so as to expose a portion of a surface of the insulating layer 112.
Next, the opening 138 is formed (see
The opening 138 is formed in a desired region so as to expose the conductive layer 110c_1. An example of a formation method of the opening 138 is, but is not limited to, a dry etching method. Alternatively, a wet etching method or a combination of dry etching and wet etching can be employed for formation of the opening 138.
Then, the pixel electrode layer 118 is formed in a desired region over the insulating layer 116 so as to cover the openings 134 and 138 (see
A material having the property of transmitting visible light may be used for the pixel electrode layer 118. For example, a material including one of indium (In), zinc (Zn), and tin (Sn) is preferably used for the pixel electrode layer 118. The pixel electrode layer 118 can be formed using a light-transmitting conductive material such as indium oxide containing tungsten oxide, indium zinc oxide containing tungsten oxide, indium oxide containing titanium oxide, indium tin oxide containing titanium oxide, indium tin oxide (ITO), indium zinc oxide, or indium tin oxide to which silicon oxide is added. The pixel electrode layer 118 can be formed by a sputtering method, for example.
Note that the pixel electrode layer 118 is connected to the conductive layer 110c_1 through the openings 134 and 138. In other words, the pixel electrode layer 118 is electrically connected to the conductive layers 110a_2 and 110b_2 serving as a drain electrode layer of the transistor 150.
Through the above process, the structure over the first substrate 102 can be formed.
Next, the first substrate 102 and the second substrate 162 are attached to each other and the liquid crystal layer 166 is formed.
Note that the second substrate 162 has the conductive layer 164. The conductive layer 164, which serves as the other electrode of the liquid crystal element 170, is preferably formed using a light-transmitting material. For the conductive layer 164, a material that can be used for the pixel electrode layer 118 can be used.
The liquid crystal layer 166 can be formed by a dispenser method (a dropping method), or an injecting method by which a liquid crystal is injected using a capillary phenomenon after the first substrate 102 and the second substrate 162 are attached to each other.
There is no particular limitation on materials that can be used for the liquid crystal layer 166, and a nematic liquid crystal material, a cholesteric liquid crystal material, or the like may be used, for example. For the liquid crystal layer 166, a polymer dispersed liquid crystal, a high molecular compound dispersed liquid crystal, a polymer network liquid crystal, or the like may be used.
Through the above process, the display device illustrated in
Although not illustrated, in this embodiment, an alignment film or an optical film such as a polarizing plate, a circularly polarizing plate (including an elliptically polarizing plate), or a retardation plate (a quarter-wave plate or a half-wave plate) may be provided as appropriate if necessary. Furthermore, the polarizing plate or the circularly polarizing plate may be provided with an anti-reflection film. For example, anti-glare treatment by which reflected light can be diffused by projections and depressions on the surface so as to reduce the glare can be performed.
Although the case of a reflective display device is described in this embodiment, one embodiment of the present invention is not limited to this example. For example, in an aperture portion of a pixel, a transmissive region may be provided. For example, in one part of an aperture portion of a pixel, a reflective region may be provided, and in another part thereof, a transmissive region may be provided. Therefore, one embodiment of the present invention can also be applied to a semi-transmissive display device.
Although the example in which the coloring layer 114 is provided with the openings 136 is described in this embodiment, one embodiment of the present invention is not limited to this example. Depending on circumstances or conditions, the coloring layer 114 is not necessarily provided with the openings 136. For example, it is possible that the opening 136 is not provided in at least one of R, G, and B pixels. Alternatively, in the case where a transmissive region and a reflective region are provided in an aperture portion of a pixel, it is possible that the coloring layer 114 is provided with the opening 136 in the reflective region and the coloring layer 114 is not provided with the opening 136 in the transmissive region.
Although the example in which the coloring layer 114 is provided over the first substrate 102 is described in this embodiment, one embodiment of the present invention is not limited to this example. Depending on circumstances or conditions, the coloring layer 114 is not necessarily provided over the first substrate 102. For example, in the case where a W (white) pixel is used in addition to the R, G, and B pixels, it is possible that the coloring layer 114 is not provided over the first substrate 102.
This embodiment can be combined with any of the other embodiments in this specification as appropriate.
Embodiment 2In this embodiment, a modification example of the display device described in Embodiment 1 is described with reference to
The display device in
Note that the conductive layer 104a, the insulating layers 106a and 106b, the semiconductor layer 108, and the conductive layers 110a_1, 110a_2, 110b_1, and 110b_2 form the transistor 150. The conductive layer 104b, the insulating layers 106a and 106b, and the conductive layers 110a_3 and 110b_3 form the capacitor 152.
Note that portions of the insulating layers 106a and 106b overlapping with the conductive layer 104a serving as a gate electrode layer have a function of the gate insulating layer of the transistor 150. In addition, portions of the insulating layers 106a and 106b overlapping with the conductive layer 104b have a function of a dielectric layer of the capacitor 152.
The insulating layers 106a and 106b are provided with the opening 132 which reaches the conductive layer 104b, and the conductive layers 110a_2 and 110b_2 having a function of a drain electrode layer of the transistor 150 are connected to the conductive layer 104b through the opening 132.
The coloring layer 114 is provided with the opening 134 and the openings 136. In other words, the insulating layer 116 over the coloring layer 114 is in contact with the insulating layer 112 in the opening 134. Note that the adhesion of the insulating layer 116 to the insulating layer 112 is higher than that of the coloring layer 114. Therefore, when there is a region where the insulating layer 116 and the insulating layer 112 are in contact with each other, separation of the coloring layer 114 can be suppressed even in the case where the adhesion between the coloring layer 114 and the insulating layer 112 is not sufficient.
The color purity of the coloring layer 114 can be adjusted with the openings 136 provided in the coloring layer 114. For example, the color purity of the coloring layer 114 can be adjusted by adjusting the shape of the openings 136 or the area of the openings 136.
With such a structure in which the coloring layer 114 has the openings 136, a novel display device capable of adjusting color purity can be provided. It addition, a novel display device with improved adhesion of the coloring layer 114 used as a color filter can be provided.
Note that the display device in
For the first substrate 202 and the second substrate 262, a material having flexibility can be used. It is preferable to use a material having flexibility and toughness for the first substrate 202 and the second substrate 262. Examples of the material having flexibility include an organic resin and glass thin enough to have flexibility.
An organic resin, which has a specific gravity smaller than that of glass, is preferably used for the first substrate 202 and the second substrate 262, in which case the display device can be more lightweight as compared with the case where glass is used.
Examples of the material having flexibility include glass thin enough to have flexibility, polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), a polyacrylonitrile resin, a polyimide resin, a polymethyl methacrylate resin, a polycarbonate (PC) resin, a polyethersulfone (PES) resin, a polyamide resin, a cycloolefin resin, a polystyrene resin, a polyamide imide resin, a polyvinyl chloride resin, and a polyether ether ketone (PEEK) resin. In particular, a material whose coefficient of thermal expansion is low is preferable, and for example, a polyamide imide resin, a polyimide resin, or PET can be suitably used. A substrate in which a glass fiber is impregnated with an organic resin or a substrate whose coefficient of thermal expansion is reduced by mixing an organic resin with an inorganic filler can also be used.
In the case where a fibrous body is contained in the material having flexibility, a high-strength fiber of an organic compound or an inorganic compound is used as the fibrous body. A high-strength fiber is specifically a fiber with a high tensile modulus of elasticity or a fiber with a high Young's modulus. Typical examples of a high-strength fiber include a polyvinyl alcohol based fiber, a polyester based fiber, a polyamide based fiber, a polyethylene based fiber, an aramid based fiber, a polyparaphenylene benzobisoxazole fiber, a glass fiber, and a carbon fiber. As the glass fiber, glass fiber using E glass, S glass, D glass, Q glass, or the like can be used. These fibers may be used in a state of a woven fabric or a nonwoven fabric, and a structure in which this fibrous body is impregnated with a resin and the resin is cured may be used. The structure including the fibrous body and the resin is preferably used, in which case the reliability against bending or breaking due to local pressure can be increased.
To improve the light extraction efficiency, the refractive index of the material having flexibility is preferably high. For example, a substrate obtained by dispersing an inorganic filler having a high refractive index into an organic resin can have a higher refractive index than the substrate formed of only the organic resin. In particular, an inorganic filler having a particle diameter as small as 40 nm or less is preferable, in which case such a filler can maintain optical transparency.
The first substrate 202 and the second substrate 262 may have a stacked-layer structure in which a hard coat layer (such as a silicon nitride layer) by which a surface of a display device is protected from damage, a layer (such as an aramid resin layer) which can disperse pressure, or the like is stacked over a surface of any of the above-mentioned materials having flexibility.
As the adhesive layers 203 and 207, various curable adhesives such as a reactive curable adhesive, a thermosetting adhesive, an anaerobic adhesive, and a photo-curable adhesive such as an ultraviolet curable adhesive can be used. Examples of such adhesives include an epoxy resin, an acrylic resin, a silicone resin, a phenol resin, a polyimide resin, an imide resin, a polyvinyl chloride (PVC) resin, a polyvinyl butyral (PVB) resin, and an ethylene vinyl acetate (EVA) resin. In particular, a material with low moisture permeability, such as an epoxy resin, is preferred. Alternatively, a two-component-mixture-type resin may be used. Further alternatively, an adhesive sheet or the like may be used.
The adhesive layers 203 and 207 may include a drying agent in a resin material. As the drying agent, for example, a substance which adsorbs moisture by chemical adsorption, such as an oxide of an alkaline earth metal (e.g., calcium oxide or barium oxide), can be used. Alternatively, a substance that adsorbs moisture by physical adsorption, such as zeolite or silica gel, may be used. The drying agent is preferably included, in which case it can suppress entry of impurities such as moisture into the display device.
For the insulating layers 205 and 209, an inorganic insulating material can be used, for example. The inorganic insulating material may have a single-layer structure or a multilayer structure of silicon nitride, silicon oxynitride, silicon nitride oxide, aluminum oxide, or the like. The insulating layers 205 and 209 have a function of buffer layers.
There is no particular limitation on the method for forming the insulating layers 205 and 209; a sputtering method, an evaporation method, a droplet discharging method (e.g., an ink-jet method), a printing method (e.g., a screen printing method or an off-set printing method), or the like may be used.
Here, an example of a method for manufacturing the display device illustrated in
As illustrated in
For the first substrate 102, any of the materials described in Embodiment 1 can be used.
The separation layer 211 can be formed to have a single-layer structure or a stacked-layer structure using an element selected from tungsten, molybdenum, titanium, tantalum, niobium, nickel, cobalt, zirconium, zinc, ruthenium, rhodium, palladium, osmium, iridium, and silicon; an alloy material containing any of the elements; a compound material containing any of the elements; or the like, for example. In the case of a layer containing silicon, a crystal structure of the layer containing silicon may be amorphous, microcrystal, polycrystal, or single crystal.
Note that between the first substrate 102 and the separation layer 211, an insulating film such as a silicon oxide film, a silicon oxynitride film, a silicon nitride film, or a silicon nitride oxide film may be formed. The insulating film is preferably formed because it can suppress entry of impurities which can be contained in the first substrate 102 to the separation layer 211 side.
The separation layer 211 can be formed by a sputtering method, a plasma CVD method, a coating method, a printing method, or the like. Note that a coating method includes a spin coating method, a droplet discharge method, and a dispensing method.
In the case where the separation layer 211 has a single-layer structure, a layer containing tungsten, molybdenum, or a mixture of tungsten and molybdenum is preferably formed. Alternatively, a layer containing an oxide or an oxynitride of tungsten, a layer containing an oxide or an oxynitride of molybdenum, or a layer containing an oxide or an oxynitride of a mixture of tungsten and molybdenum may be formed. Note that the mixture of tungsten and molybdenum corresponds to an alloy of tungsten and molybdenum, for example.
In the case where the separation layer 211 is formed to have a stacked-layer structure including a layer containing tungsten and a layer containing an oxide of tungsten, the layer containing an oxide of tungsten may be formed as follows: the layer containing tungsten is formed first and an insulating layer formed of an oxide is formed thereover, so that the layer containing an oxide of tungsten is formed at the interface between the tungsten layer and the insulating layer. Alternatively, the layer containing an oxide of tungsten may be formed by performing thermal oxidation treatment, oxygen plasma treatment, nitrous oxide (N2O) plasma treatment, treatment with a highly oxidizing solution such as ozone water, or the like on the surface of the layer containing tungsten. Plasma treatment or heat treatment may be performed in an atmosphere of oxygen, nitrogen, or nitrous oxide alone, or a mixed gas of any of these gasses and another gas. Surface condition of the separation layer 211 is changed by the plasma treatment or heat treatment, whereby adhesion between the separation layer 211 and the insulating layer 205 formed later can be controlled.
In this embodiment, a 30-nm-thick tungsten film is formed as the separation layer 211 by a sputtering method.
The insulating layer 205 can be formed using any of the above-listed materials. For example, in this embodiment, the insulating layer 205 is formed at a temperature of higher than or equal to 250° C. and lower than or equal to 400° C. by a plasma CVD method, whereby the insulating layer 205 can be a dense film with low water permeability. Note that the thickness of the insulating layer 205 is preferably greater than or equal to 10 nm and less than or equal to 3000 nm, further preferably greater than or equal to 200 nm and less than or equal to 1500 nm. In this embodiment, a 600-nm-thick silicon oxynitride film is formed by a plasma CVD method and then a 200-nm-thick silicon nitride film is formed over the silicon oxynitride by a plasma CVD method.
Next, the conductive layers 104a and 104b are formed over the insulating layer 205. Subsequent steps are similar to those for components in Embodiment 1; thus, components can be formed with reference to the description in Embodiment 1.
Next, a material to be an adhesive layer is applied to an element substrate where the transistor 150, the capacitor 152, and the like are formed (in
Note that any of a variety of methods can be used as appropriate in the step of causing separation between the separation layer 211 and the insulating layer 205. For example, when a layer including a metal oxide film is formed as the separation layer 211 on the side in contact with a layer to be separated (in
Alternatively, when a substrate having high heat resistance is used as the first substrate 102 and when an amorphous silicon film containing hydrogen is formed as the separation layer 211 between the substrate having high heat resistance and the layer to be separated, the amorphous silicon film is removed by laser light irradiation or etching, whereby the layer to be separated can be separated from the first substrate 102.
Alternatively, after a layer including a metal oxide film is formed as the separation layer 211 on the side in contact with the layer to be separated, the metal oxide film is embrittled by crystallization, and part of the separation layer is removed by etching using a solution or a fluoride gas such as NF3. BrF3, or ClF3, whereby the separation can be performed at the embrittled metal oxide film.
A method may be used in which a film containing nitrogen, oxygen, hydrogen, or the like (for example, an amorphous silicon film containing hydrogen, an alloy film containing hydrogen, an alloy film containing oxygen, or the like) is used as the separation layer 211, and the separation layer 211 is irradiated with laser light to release nitrogen, oxygen, or hydrogen contained in the separation layer 211 as a gas, thereby promoting separation between the layer to be separated and the substrate.
Further, the separation process can be conducted easily by combination of the above-described separation steps. For example, separation can be performed with physical force (by a machine or the like) after performing laser light irradiation, etching on the separation layer with a gas, a solution, or the like, or mechanical removal with a sharp knife, a scalpel, or the like so that the separation layer and the layer to be separated can be easily separated from each other.
Separation of the layer to be separated from the first substrate 102 may be carried out by filling the interface between the separation layer 211 and the layer to be separated with a liquid. Further, the separation may be conducted while pouring a liquid such as water. In the case where the separation layer 211 is formed using a tungsten film, it is preferable that the separation be performed while etching the tungsten film using a mixed solution of ammonia water and a hydrogen peroxide solution.
Note that the separation layer 211 is not necessary in the case where separation at the interface between the first substrate 102 and the layer to be separated is possible. For example, glass is used as the first substrate 102, an organic resin such as polyimide is formed in contact with the glass, and an insulating film, a transistor, and the like are formed over the organic resin. In this case, heating the organic resin enables the separation at the interface between the first substrate 102 and the organic resin. Alternatively, separation at the interface between a metal layer and the organic resin may be performed in the following manner: the metal layer is provided between the first substrate 102 and the organic resin and current is made to flow in the metal layer so that the metal layer is heated.
Through the above steps, the transistor 150, the capacitor 152, and the like formed over the first substrate 102 can be transferred to the first substrate 202 having flexibility.
Note that transfer from the second substrate 162 to the second substrate 262 can be performed by a similar method. Note that the second substrate 262 is not provided with elements such as the transistor 150 and the capacitor 152, therefore, the conductive layer 164 may be formed directly over the second substrate 262. In that case, the adhesive layer 207 and the insulating layer 209 are not provided.
Next, the first substrate 202 and the second substrate 262 are attached and the liquid crystal layer 166 is injected between the first substrate 202 and the second substrate 262. Thus, the display device in
Since the first substrate 202 and the second substrate 262 of the material having flexibility are used in the display device described in this embodiment, the display device can be flexible. In the case where the material having flexibility and toughness is used for each of the first and second substrates 202 and 262, a display device with high impact resistance that is less likely to be broken can be obtained.
In the display device in
Note that a substrate formed using the material having flexibility may be similarly used in other drawings such as
This embodiment can be combined with any of the other embodiments as appropriate.
Embodiment 3In this embodiment, a display device of one embodiment of the present invention will be described with reference to
The display device illustrated in
A part or the whole of the driver circuit portion 304 is preferably formed over a substrate over which the pixel portion 302 is formed, in which case the number of components and the number of terminals can be reduced. When a part or the whole of the driver circuit portion 304 is not formed over the substrate over which the pixel portion 302 is formed, the part or the whole of the driver circuit portion 304 can be mounted by chip-on-glass (COG) or tape automated bonding (TAB).
The pixel portion 302 includes a plurality of circuits for driving display elements arranged in X rows (X is a natural number of 2 or more) and Y columns (Y is a natural number of 2 or more) (hereinafter, such circuits are referred to as pixel circuits 308). The driver circuit portion 304 includes driver circuits such as a circuit for supplying a signal (scan signal) to select a pixel (hereinafter, the circuit is referred to as a gate driver 304a) and a circuit for supplying a signal (data signal) to drive a display element in a pixel (hereinafter, the circuit is referred to as a source driver 304b).
The gate driver 304a includes a shift register or the like. The gate driver 304a receives a signal for driving the shift register through the terminal portion 307 and outputs a signal. For example, the gate driver 304a receives a start pulse signal, a clock signal, or the like and outputs a pulse signal. The gate driver 304a has a function of controlling the potentials of wirings supplied with scan signals (hereinafter, such wirings are referred to as gate lines GL_1 to GL_X, and the gate lines may also be referred to as scan lines). Note that a plurality of gate drivers 304a may be provided to control the gate lines GL_1 to GL_X separately. Alternatively, the gate driver 304a has a function of supplying an initialization signal. Without being limited thereto, the gate driver 304a can supply another signal.
The source driver 304b includes a shift register or the like. The source driver 304b receives a signal (video signal) from which a data signal is derived, as well as a signal for driving the shift register, through the terminal portion 307. The source driver 304b has a function of generating a data signal to be written to the pixel circuit 308 which is based on the video signal. In addition, the source driver 304b has a function of controlling output of a data signal in response to a pulse signal produced by input of a start pulse signal, a clock signal, or the like. Further, the source driver 304b has a function of controlling the potentials of wirings supplied with data signals (hereinafter, such wirings are referred to as source lines DL_1 to DL_Y, and the source lines may also be referred to as data lines). Alternatively, the source driver 304b has a function of supplying an initialization signal. Without being limited thereto, the source driver 304b can supply another signal.
The source driver 304b includes a plurality of analog switches or the like, for example. The source driver 304b can output, as the data signals, signals obtained by time-dividing the video signal by sequentially turning on the plurality of analog switches. The source driver 304b may include a shift register or the like.
A pulse signal and a data signal are input to each of the plurality of pixel circuits 308 through one of the plurality of gate lines GL supplied with scan signals and one of the plurality of source lines DL supplied with data signals, respectively. Writing and holding of the data signal to and in each of the plurality of pixel circuits 308 are controlled by the gate driver 304a. For example, to the pixel circuit 308 in the m-th row and the n-th column (m is a natural number of less than or equal to X, and n is a natural number of less than or equal to Y), a pulse signal is input from the gate driver 304a through the gate line GL_m, and a data signal is input from the source driver 304b through the source line DL_n in accordance with the potential of the gate line GL_m.
The protection circuit portion 306 shown in
The protection circuit portion 306 is a circuit that electrically connects a wiring connected to the protection circuit portion to another wiring when a potential out of a certain range is applied to the wiring connected to the protection circuit portion.
As illustrated in
In
Each of the plurality of pixel circuits 308 in
The pixel circuit 308 illustrated in
The potential of one of a pair of electrodes of the liquid crystal element 170 is set in accordance with the specifications of the pixel circuit 308 as appropriate. The alignment state of the liquid crystal element 170 depends on written data. A common potential may be supplied to one of the pair of electrodes of the liquid crystal element 170 included in each of the plurality of pixel circuits 308. Further, the potential supplied to one of the pair of electrodes of the liquid crystal element 170 in the pixel circuit 308 in one row may be different from the potential supplied to one of the pair of electrodes of the liquid crystal element 170 in the pixel circuit 308 in another row.
As examples of a driving method of the display device including the liquid crystal element 170, any of the following modes can be given: a TN mode, an STN mode, a VA mode, an axially symmetric aligned micro-cell (ASM) mode, an optically compensated birefringence (OCB) mode, a ferroelectric liquid crystal (FLC) mode, an antiferroelectric liquid crystal (AFLC) mode, an MVA mode, a patterned vertical alignment (PVA) mode, an IPS mode, an FFS mode, a transverse bend alignment (TBA) mode, and the like. Other examples of the driving method of the display device include an electrically controlled birefringence (ECB) mode, a polymer dispersed liquid crystal (PDLC) mode, a polymer network liquid crystal (PNLC) mode, and a guest-host mode. Note that the present invention is not limited to these examples, and various liquid crystal elements and driving methods can be applied to the liquid crystal element and the driving method thereof.
The liquid crystal element may be formed using a liquid crystal composition including liquid crystal exhibiting a blue phase and a chiral material. The liquid crystal exhibiting a blue phase has a short response time of 1 msec or less and is optically isotropic. Therefore, alignment treatment is not necessary and viewing angle dependence is small.
In the pixel circuit 308 in the m-th row and the n-th column, one of a source and a drain of the transistor 150 is electrically connected to the source line DL_n, and the other is electrically connected to the other of the pair of electrodes of the liquid crystal element 170. A gate of the transistor 150 is electrically connected to the gate line GL_m. The transistor 150 has a function of controlling whether to write a data signal by being turned on or off.
One of a pair of electrodes of the capacitor 152 is electrically connected to a wiring to which a potential is supplied (hereinafter referred to as a potential supply line VL), and the other is electrically connected to the other of the pair of electrodes of the liquid crystal element 170. The potential of the potential supply line VL is set in accordance with the specifications of the pixel circuit 308 as appropriate. The capacitor 152 functions as a storage capacitor for storing written data.
For example, in the display device including the pixel circuit 308 in
When the transistors 150 are turned off, the pixel circuits 308 in which the data has been written are brought into a holding state. This operation is sequentially performed row by row; thus, an image can be displayed.
The structure described in this embodiment can be combined with any of the structures described in the other embodiments as appropriate.
Embodiment 4In this embodiment, a display module and electronic devices that can be formed using a display device of one embodiment of the present invention are described with reference to
In a display module 8000 illustrated in
The display device of one embodiment of the present invention can be used for, for example, the display panel 8006.
The shapes and sizes of the upper cover 8001 and the lower cover 8002 can be changed as appropriate in accordance with the sizes of the touch panel 8004 and the display panel 8006.
The touch panel 8004 can be a resistive touch panel or a capacitive touch panel and can be formed to overlap with the display panel 8006. A counter substrate (sealing substrate) of the display panel 8006 can have a touch panel function. A photosensor may be provided in each pixel of the display panel 8006 to form an optical touch panel.
The backlight unit 8007 includes a light source 8008. Note that although a structure in which the light sources 8008 are provided over the backlight unit 8007 is illustrated in
Note that the backlight unit 8007 need not be provided in the case of a reflective liquid crystal display device. The backlight unit 8007 is provided in the case of a transmissive liquid crystal display device or a semi-transmissive liquid crystal display device, for example.
The frame 8009 protects the display panel 8006 and also functions as an electromagnetic shield for blocking electromagnetic waves generated by the operation of the printed board 8010. The frame 8009 may function as a radiator plate.
The printed board 8010 is provided with a power supply circuit and a signal processing circuit for outputting a video signal and a clock signal. As a power source for supplying power to the power supply circuit, an external commercial power source or a power source using the battery 8011 provided separately may be used. The battery 8011 can be omitted in the case of using a commercial power source.
The display module 8000 may be additionally provided with a member such as a polarizing plate, a retardation plate, or a prism sheet.
The electronic devices illustrated in
The electronic devices described in this embodiment each include the display portion for displaying some sort of data.
The structure described in this embodiment can be combined with any of the structures described in the other embodiments as appropriate.
Embodiment 5In this embodiment, a modification example of the display device described in Embodiment 1 is described with reference to
This embodiment describes an example in which a pixel electrode layer is used as a reflective electrode and a substrate 162 that is a counter substrate is provided with a coloring layer, a BM 180, and a spacer 181. The position of overlap with openings in the coloring layer and the position of overlap with the spacer 181 are indicated by dotted lines. The transistor 150 has the same structure as that in Embodiment 1 except that a 400-nm-thick tungsten film is used as a conductive layer; thus, detailed description is omitted here. Note that the transistor 150 has a channel length L of 3 μm and a channel width W of 3 μm. The transistor 150 includes a 50-nm-thick In—Ga—Zn oxide (In:Ga:Zn=1:1:1 (at. %)) semiconductor layer formed with a sputtering apparatus.
The pixel electrode layer 118 electrically connected to the transistor 150 through the opening 138 overlaps with part of the gate line 104, and has a large reflection area. Note that the transistor 150 is positioned so as to overlap with the BM 180. As the BM 180, a 200-nm-thick titanium film formed with a sputtering apparatus is used.
This embodiment describes an example in which openings in the coloring layers 114 have different shapes for different colors of pixels, as illustrated in
In each of
The upper surface shapes of the openings illustrated in
The display device in
As the overcoat layer 182, an acrylic based resin film is used, which is formed by applying an acrylic based resin material with a spin coater apparatus and then drying the material in an oven apparatus. As for the coloring layer 114, three colors of red (R), green (G), and blue (B) are used, and green (G), red (R), and blue (B) color filters are formed in this order in desired positions by light exposure and development. Each of the red (R), green (G), and blue (B) color filters is formed so as to have a thickness of 0.8 μm.
Note that the conductive layer 104a, the insulating layers 106a and 106b, the semiconductor layer 108, and the conductive layers 110a_1 and 110a_2 form the transistor 150. The conductive layer 104b, the insulating layers 106a and 106b, and the conductive layer 110a_2 form the capacitor 152. The capacitor 152 has a large area and thus has a large capacitance for charge storage. Thus, it is possible to retain the potential of the pixel electrode for a longer time and to apply a driving mode with a reduced refresh rate. Furthermore, a change in voltage applied to the liquid crystal layer can be inhibited for a long time even when the liquid crystal display device is used in the driving mode with a reduced refresh rate. This makes it possible to prevent screen flickers from being perceived by a user more effectively. Thus, the power consumption can be reduced and the display quality can be improved.
An effect of reducing the refresh rate will be described here. Note that the refresh rate refers to the number of times of image writing per second and is also called driving frequency. Such high-speed screen switching that is difficult for the human eye to perceive is considered as a cause of eye strain.
The eye strain is divided into two categories: nerve strain and muscle strain. The nerve strain is caused by prolonged looking at light emitted from a liquid crystal display device or blinking images. This is because the brightness stimulates and fatigues the retina and nerve of the eye and the brain. The muscle strain is caused by overuse of a ciliary muscle which works for adjusting the focus.
In this embodiment, a transistor with an extremely low off-state current (e.g., a transistor using an oxide semiconductor) is used as the transistor 150 in a pixel portion of a liquid crystal display device. In addition, the liquid crystal element has a large-area capacitor. With these components, leakage of electrical charges stored in the capacitor can be inhibited, whereby the luminance of a liquid crystal display device can be kept even at a lower frame frequency.
Thus, for example, the number of times of image writing can be reduced to once every five seconds as shown in
This embodiment makes it possible to provide an eye-friendly liquid crystal display device.
The refresh operation needs to be performed such that a change of an image caused by the refresh operation is not distinguished by users. The display device according to this embodiment has little change of an image caused by the refresh operation and can perform favorable display.
The coloring layer 114 formed on the second substrate 162 side is provided with a plurality of openings 136. The color purity of the coloring layer 114 can be adjusted by setting the shape or area of the openings 136 provided in the coloring layer 114. With such a structure in which the coloring layer 114 has the openings 136, a novel display device capable of adjusting color purity can be provided.
The insulating layer 112 is provided with the opening 138. The pixel electrode layer 118 is connected to the conductive layer 110a_2 serving as a drain electrode layer of the transistor 150, through the opening 138. For the insulating layer 116, a photosensitive resin may be used so that random projections and depressions are formed. In the case where random projections and depressions are formed, the pixel electrode layer 118 is a reflective electrode having random projections and depressions reflecting the random projections and depressions on the surface of the insulating layer 116. Thus, viewing angle dependence can be improved.
In this embodiment, a highly reflective conductive layer is used as the pixel electrode layer 118 so as to serve as a reflective electrode. For example, the highly reflective conductive layer is formed to have a single-layer structure or a stacked-layer structure including any of metals such as aluminum, silver, palladium, and copper or an alloy containing any of these metals as its main component.
In the display device in
When the BM 180 is formed as illustrated in
In this manner, the BM 180 is preferably formed in a portion other than at least a reflective region.
This embodiment can be freely combined with any of the other embodiments.
Example 1In this example, a display device of one embodiment of the present invention was manufactured and subjected to optical microscope observation and cross-sectional observation. Details of samples manufactured in this example are described below.
Note that a display device having a structure similar to that of the display device illustrated in
A method for manufacturing the samples which were observed in this example will be described below.
As the first substrate 102, a glass substrate was used. Then, the conductive layers 104a. 104b, and 104c were formed over the first substrate 102. A 200-nm-thick tungsten film (W) was formed by a sputtering method for the conductive layers 104a, 104b, and 104c.
Then, the insulating layers 106a and 106b serving as a gate insulating layer were formed over the first substrate 102 and the conductive layers 104a, 104b, and 104c. A 400-nm-thick silicon nitride film was formed as the insulating layer 106a, and a 50-nm-thick silicon oxynitride film was formed as the insulating layer 106b.
Note that the silicon nitride film that is the insulating layer 106a has a three-layer structure of a first silicon nitride film, a second silicon nitride film, and a third silicon nitride film.
The first silicon nitride film was formed to have a thickness of 50 nm under the following conditions: silane at a flow rate of 200 sccm, nitrogen at a flow rate of 2000 sccm and an ammonia gas at a flow rate of 100 sccm were supplied to a reaction chamber of a plasma CVD apparatus as a source gas, the pressure in the reaction chamber was controlled to 100 Pa, and a power of 2000 W was supplied with the use of a 27.12 MHz high-frequency power source. The second silicon nitride film was formed to have a thickness of 300 nm under the following conditions: silane at a flow rate of 200 sccm, nitrogen at a flow rate of 2000 sccm, and an ammonia gas at a flow rate of 2000 sccm were supplied to the reaction chamber of the plasma CVD apparatus as a source gas, the pressure in the reaction chamber was controlled to 100 Pa, and a power of 2000 W was supplied with the use of a 27.12 MHz high-frequency power source. The third silicon nitride film was formed to have a thickness of 50 nm under the following conditions: silane at a flow rate of 200 sccm and nitrogen at a flow rate of 5000 sccm were supplied to the reaction chamber of the plasma CVD apparatus as a source gas, the pressure in the reaction chamber was controlled to 100 Pa, and a power of 2000 W was supplied with the use of a 27.12 MHz high-frequency power source. Note that the first silicon nitride film, the second silicon nitride film, and the third silicon nitride film were each formed at a substrate temperature of 350° C.
The silicon oxynitride film formed as the insulating layer 106b was formed under the following conditions: silane at a flow rate of 20 sccm and dinitrogen monoxide at a flow rate of 3000 sccm were supplied to the reaction chamber of the plasma CVD apparatus as a source gas, the pressure in the reaction chamber was controlled to 40 Pa, and a power of 100 W was supplied with the use of a 27.12 MHz high-frequency power source. Note that the silicon oxynitride film was formed at a substrate temperature of 350° C.
Next, the semiconductor layer 108 was formed so as to overlap with the conductive layer 104a with the insulating layers 106a and 106b provided therebetween. A 35-nm-thick oxide semiconductor film was formed as the semiconductor layer 108 by a sputtering method.
The oxide semiconductor film was formed under the following conditions: a metal oxide sputtering target of In:Ga:Zn=1:1:1 (atomic ratio) was used, oxygen at a flow rate of 100 sccm and argon at a flow rate of 100 sccm were supplied as a sputtering gas to a reaction chamber of a sputtering apparatus, the pressure in the reaction chamber was controlled to 0.6 Pa, and an alternating-current power of 2.5 kW was supplied. Note that the oxide semiconductor film was formed at a substrate temperature of 170° C.
Next, the opening 132 was formed in a desired position of the insulating layers 106a and 106b. Note that the opening 132 reaches the conductive layer 104b.
The opening 132 was formed using a dry etching apparatus.
Next, a conductive layer was formed over the semiconductor layer 108 and the insulating layers 106a and 106b. As the conductive layer, a 400-nm-thick aluminum film was formed over a 50-nm-thick tungsten film, and a 100-nm-thick titanium film was formed over the aluminum film.
Next, a conductive layer 110_1 was formed by removing a region other than a desired region of the 100-nm-thick titanium film with a dry etching apparatus. Note that the conductive layer 110_1 is a 100-nm-thick titanium film.
Next, the conductive layers 110a_1, 110a_2, 110a_3, 110a_4, 110b_1, 110b_2, 110b_3, and 110b_4 were formed by processing the 50-nm-thick tungsten film and the 400-nm-thick aluminum film into a desired shape with a dry etching apparatus. Note that the conductive layers 110a1, 110a_2, 10a_3, and 110a_4 are each a 50-nm-thick tungsten film. The conductive layers 110b_1, 110b_2, 110b_3, and 110b_4 are each a 400-nm-thick aluminum film.
The conductive layers 110a_1 and 110b_1 serve as a source electrode layer of a transistor; the conductive layers 110a_2 and 110b_2 serve as a drain electrode layer of the transistor; the conductive layers 110a_3 and 110b_3 serve as a reflective electrode layer; and the conductive layers 110a_4 and 110b_4 serve as part of a source line.
Next, the insulating layer 112 was formed so as to cover the semiconductor layer 108 and the conductive layers 110b_1, 110b_2, 110b_3, and 110c_1.
The insulating layer 112 was formed to have a three-layer structure of a first oxide insulating film, a second oxide insulating film, and a nitride insulating film.
A 50-nm-thick silicon oxynitride film was formed as the first oxide insulating film. A 400-nm-thick silicon oxynitride film was formed as the second oxide insulating film. Note that the first oxide insulating film and the second oxide insulating film were successively formed with a plasma CVD apparatus in vacuum without exposure to the air. Since the first oxide insulating film and the second oxide insulating film were formed using the same kind of material, the interface between these films cannot be clearly defined in some cases.
The first oxide insulating film was formed by a plasma CVD method under the following conditions: silane at a flow rate of 30 sccm and dinitrogen monoxide at a flow rate of 4000 sccm were used as a source gas, the pressure in the reaction chamber was 40 Pa, the substrate temperature was 220° C., and a high-frequency power of 150 W was supplied to parallel-plate electrodes.
The second oxide insulating film was formed by a plasma CVD method under the following conditions: silane at a flow rate of 160 sccm and dinitrogen monoxide at a flow rate of 4000 sccm were used as a source gas, the pressure in the reaction chamber was 200 Pa, the substrate temperature was 220° C., and a high-frequency power of 1500 W was supplied to the parallel-plate electrodes. Under the above conditions, it is possible to form a silicon oxynitride film containing oxygen at a higher proportion than oxygen in the stoichiometric composition and from which part of oxygen is released by heating.
Next, heat treatment was performed to release water, nitrogen, hydrogen, and the like from the first oxide insulating film and the second oxide insulating film and supply part of oxygen contained in the second oxide insulating film to the oxide semiconductor film used as the semiconductor layer 108. Here, the heat treatment was performed at 350° C. in a mixed atmosphere of nitrogen and oxygen for one hour.
Then, a 100-nm-thick nitride insulating film was formed over the second oxide insulating film. A 100-nm-thick silicon nitride film was formed as the nitride insulating film. The nitride insulating film was formed by a plasma CVD method under the following conditions: silane at a flow rate of 50 sccm, nitrogen at a flow rate of 5000 sccm, and an ammonia gas at a flow rate of 100 sccm were used as a source gas, the pressure in the reaction chamber was 100 Pa, the substrate temperature was 350° C., and a high-frequency power of 1000 W was supplied to the parallel-plate electrodes.
Next, the coloring layer 114 was formed in a desired region over the insulating layer 112.
As the coloring layer 114, a photosensitive resin film was formed by applying a photosensitive resin solution in which a coloring material was dispersed, with a spin coater apparatus and then drying the solution in an oven apparatus. The photosensitive resin film serves as a so-called color filter. Note that in this example, three colors of red (R), green (G), and blue (B) are used, and green (G), red (R), and blue (B) color filters were formed in this order in desired positions by light exposure and development. Each of the red (R), green (G), and blue (B) color filters was formed so as to have a thickness of 0.8 μm. The coloring layer 114 was formed such that the opening 134 and the opening 136 were provided for each of the above colors.
Next, the insulating layer 116 having a function of an overcoat was formed over the insulating layer 112 and the coloring layer 114. Note that as the insulating layer 116, an acrylic based resin film was formed by applying an acrylic based resin material with a spin coater apparatus and then drying the material in an oven apparatus. The insulating layer 116 was formed so as to have a thickness of 2.5 μm. In addition, the insulating layer 116 was formed such that an opening is provided inside the opening 134 in the coloring layer 114.
Next, the opening 138 was formed in the insulating layer 112 in a position overlapping the opening 134. The opening 138 was formed so as to reach the conductive layer 110c_1. Note that the opening 138 was formed using a dry etching apparatus.
Next, the pixel electrode layer 118 was formed over the insulating layer 116 so as to cover the opening 138. A 100-nm-thick conductive film of an indium oxide-tin oxide-silicon oxide compound (ITO-SiO2, hereinafter ITSO) was formed as the pixel electrode layer 118 by a sputtering method. Note that the composition of a target used for forming the conductive film was In2O3:SnO2:SiO2=85:10:5 [wt %].
Through these steps, elements were formed over the first substrate 102. These samples were subjected to optical microscope observation.
Note that in this example, in order to observe the elements formed over the first substrate 102, the liquid crystal layer 166, the conductive layer 164, and the second substrate 162 were not formed over the insulating layer 116 and the pixel electrode layer 118.
In addition,
As shown in
In addition, favorable color purity was visually observed from all the samples in
Note that the proportion of the area of the coloring layer 114 in
Next, results of cross-sectional observation of the samples manufactured in this example are described with reference to
Note that
Note that in
The results shown in the TEM images in
As can be seen from the result shown in the TEM image in
The structure described above in this example can be combined with any of the structures described in the other embodiments as appropriate.
Example 2In this example, a display device of one embodiment of the present invention was manufactured, a pixel region where an image was displayed was photographed, and its reflectance was measured. Details of samples manufactured in this example are described below.
Note that the display device described in Embodiment 5 and illustrated in
Two types of display panels which are the manufactured samples were subjected to reflectance measurement using a measurement apparatus (an LCD evaluation apparatus (product name: LCD-7200)) such that a detector was positioned over the center of the display panel so as to be perpendicular to the display panel surface and the center of the panel was irradiated with light from a light source at an angle in the range from 15° to 70°, as illustrated in
The upper curve in
These panels can further be provided with a touch panel so as to be a display device capable of touch input.
Note that the data in
These data indicate that a reflective liquid crystal display device capable of high-resolution display can be obtained.
Furthermore, these display panels include capacitors with a large capacitance. Thus, it is possible to retain the potential of the pixel electrode for a longer time and to apply a driving mode with a reduced refresh rate. Moreover, a change in voltage applied to the liquid crystal layer can be inhibited for a long time even when the liquid crystal display device is used in the driving mode with a reduced refresh rate. This makes it possible to prevent screen flickers from being perceived by a user more effectively. Thus, the power consumption can be reduced and the display quality can be improved.
The display device of this example can be used in a driving mode with a reduced refresh rate of 1 Hz or less and can be an eye-friendly reflective liquid crystal display device. The display device of this example can also be a low-power-consumption reflective liquid crystal display device.
This application is based on Japanese Patent Application serial no. 2013-216904 filed with Japan Patent Office on Oct. 18, 2013 and Japanese Patent Application serial no. 2014-005432 filed with Japan Patent Office on Jan. 15, 2014, the entire contents of which are hereby incorporated by reference.
Claims
1. A display device comprising:
- a first substrate;
- a transistor over the first substrate;
- an electrode layer electrically connected to the transistor;
- a first insulating layer over the electrode layer;
- a pixel electrode layer over the first insulating layer;
- a second insulating layer over the pixel electrode layer;
- a first coloring layer over the second insulating layer, the first coloring layer overlapping with the electrode layer and the pixel electrode layer; and
- a second substrate over the first coloring layer,
- wherein the first coloring layer includes a first opening, and
- wherein the second insulating layer is in contact with the second substrate in the first opening.
2. The display device according to claim 1 further comprising a second coloring layer,
- wherein the second coloring layer includes a second opening, and
- wherein an upper surface shape of the second opening is different from an upper surface shape of the first opening.
3. The display device according to claim 1,
- wherein the pixel electrode layer is a reflective electrode layer.
4. The display device according to claim 1,
- wherein the transistor comprises a gate electrode layer, a gate insulating layer and a semiconductor layer, the gate electrode layer overlapping with the semiconductor layer,
- wherein the gate insulating layer is provided between the gate electrode layer and the semiconductor layer, and
- wherein a source electrode layer and a drain electrode layer are in contact with the gate insulating layer and the semiconductor layer.
5. The display device according to claim 4,
- wherein the semiconductor layer comprises an oxide semiconductor.
6. The display device according to claim 5,
- wherein the oxide semiconductor includes an oxide represented by an In-M-Zn oxide containing at least indium (In), zinc (Zn), and M, and
- wherein M represents Al, Ga, Ge, Y, Zr, Sn, La, Ce, or Hf.
7. An electronic device comprising the display device according to claim 1.
Type: Application
Filed: Jan 17, 2017
Publication Date: May 4, 2017
Inventors: Masataka NAKADA (Tochigi), Hidenori MORI (Kawachi), Hisashi OHTANI (Tochigi)
Application Number: 15/407,686
