Abstract: A semiconductor thin film is formed having a lateral growth region which is a collection of columnar or needle-like crystals extending generally parallel with a substrate. The semiconductor thin film is illuminated with laser light or strong light having equivalent energy. As a result, adjacent columnar or needle-like crystals are joined together to form a region having substantially no grain boundaries, i.e., a monodomain region which can substantially be regarded as a single crystal. A semiconductor device is formed by using the monodomain region as an active layer.
Type:
Grant
Filed:
February 15, 2002
Date of Patent:
August 26, 2003
Assignee:
Semiconductor Energy Laboratory Co., Ltd.
Inventors:
Shunpei Yamazaki, Akiharu Miyanaga, Jun Koyama, Takeshi Fukunaga
Abstract: Semiconductor devices based on thin film transistors formed over substrates. In one embodiment, a semiconductor device comprises at least two thin film transistors formed over a substrate, each of said thin film transistors having a crystalline semiconductor film comprising silicon formed on an insulating surface as an active region thereof, wherein said crystalline semiconductor film of each of said two thin film transistors has substantially no grain boundary therein, and a crystal axis of said crystalline semiconductor film in one of said two thin film transistors deviates from a crystal axis of the crystalline semiconductor film of the other, and the deviation of the crystal axis is within ±10°.
Type:
Grant
Filed:
August 27, 2001
Date of Patent:
August 26, 2003
Assignee:
Semiconductor Energy Laboratory Co., Ltd.
Abstract: A pixel is provided in which normal display of an image is possible even if a sustain period is shorter than an address period in a driving method combining digital gray scales and time gray scales, and in which operation can be compensated by changing the electric potential of a signal line even for a case in which the EL driver transistor becomes normally on due to deterioration. One of a source region and a drain region of an erasure TFT is connected to an electric current supply line, and the remaining one of the source region and the drain region is connected to a gate signal line. It is possible to change the voltage between a gate and a source of an EL driver TFT by changing the electric potential of the gate signal line so that the EL driver TFT is placed in a non-conducting state with certainty with this structure, even for cases in which the EL driver TFT becomes normally on due to a shift in the value of its threshold voltage.
Type:
Grant
Filed:
April 25, 2001
Date of Patent:
August 26, 2003
Assignee:
Semiconductor Energy Laboratory Co., Ltd.
Abstract: A semiconductor display device which comprises the polycrystalline silicon TFTs is constructed by a pixel region and a peripheral circuit and TFT characteristics required for each circuit are different. For example, an LDD structure TFT having a large off-current suppressing effect is suitable for the pixel region. Also, a GOLD structure TFT having a large hot carrier resistance is suitable for the peripheral circuit. When the performance of the semiconductor display device is improved, it is suitable that difference TFT structures are used for each circuit. In the case where the GOLD structure TFT having both Lov regions and Loff regions is formed, ion implantation into the Lov regions is independently performed using a negative resist pattern formed in a self alignment by a rear surface exposure method as a mask, and thus impurity concentrations of the Lov regions and the Loff regions can be independently controlled.
Type:
Application
Filed:
March 11, 2003
Publication date:
August 21, 2003
Applicant:
Semiconductor Energy Laboratory Co., Ltd.
Abstract: An active layer of an NTFT includes a channel forming region, at least a first impurity region, at least a second impurity region and at least a third impurity region therein. Concentrations of an impurity in each of the first, second and third impurity regions increase as distances from the channel forming region become longer. The first impurity region is formed to be overlapped with a side wall. A gate overlapping structure can be realized with the side wall functioning as an electrode.
Type:
Application
Filed:
January 8, 2003
Publication date:
August 21, 2003
Applicant:
Semiconductor Energy Laboratory Co., Ltd.
Abstract: A hydrogenation method that utilizes plasma directly exposes a crystalline semiconductor film to the plasma, and therefore involves the problem that the crystalline semiconductor film is damaged by the ions generated simultaneously in the plasma. If a substrate is heated to 400° C. or above to recover this damage, hydrogen is re-emitted from the crystalline semiconductor film.
Type:
Application
Filed:
November 5, 2002
Publication date:
August 21, 2003
Applicant:
Semiconductor Energy Laboratory Co., Ltd.
Abstract: A high performance circuit is formed by using a TFT with less fluctuation in characteristics, and a semiconductor device including such a circuit is formed. When the TFT is formed, first, a base film and a semiconductor film are continuously formed on a quartz substrate without exposing to the air. After the semiconductor film is crystallized by using a catalytic element, the catalytic element is removed. In the TFT formed in such a process, fluctuation in electrical characteristics such as a threshold voltage and a subthreshold coefficient is extremely small. Thus, it is possible to form a circuit, such as a differential amplifier circuit, which is apt to receive an influence of characteristic fluctuation of a TFT.
Type:
Application
Filed:
February 26, 2003
Publication date:
August 21, 2003
Applicant:
Semiconductor Energy Laboratory Co., Ltd.
Inventors:
Hisashi Ohtani, Jun Koyama, Shunpei Yamazaki
Abstract: A method of manufacturing a gate-insulated thin film transistor is disclosed. One improvement is that the thin film transistor is formed on a substrate with a blocking layer in between so that it is possible to prevent the transistor from being contaminated with impurities such as alkali ions which exist in the substrate. Also, a halogen is added to either or both of the blocking layer and a gate insulator of the transistor in order that impurities such as alkaline ions, dangling bonds and the like can be neutralized. Therefore, the reliability of the device is improved.
Type:
Grant
Filed:
March 6, 1996
Date of Patent:
August 19, 2003
Assignee:
Semiconductor Energy Laboratory Co., Ltd.
Abstract: A semiconductor device having high carrier mobility, which comprises a substrate provided thereon a base film and further thereon a crystalline non-single crystal silicon film by crystal growth, wherein, the crystals are grown along the crystallographic [110] axis, and source/drain regions are provided approximately along the direction of carrier movement which coincides to the direction of crystal growth. Moreover, the electric conductivity along this direction of crystal growth is higher than any in other directions.
Type:
Grant
Filed:
January 5, 2000
Date of Patent:
August 19, 2003
Assignee:
Semiconductor Energy Laboratory Co., Ltd.
Abstract: A semiconductor device and a process for production thereof, said semiconductor device having a new electrode structure which has a low resistivity and withstands heat treatment at 400° C. and above. Heat treatment at a high temperature (400-700° C.) is possible because the wiring is made of Ta film or Ta-based film having high heat resistance. This heat treatment permits the gettering of metal element in crystalline silicon film. Since this heat treatment is lower than the temperature which the gate wiring (0.1-5 &mgr;m wide) withstands and the gate wiring is protected with a protective film, the gate wiring retains its low resistance.
Type:
Grant
Filed:
August 21, 2000
Date of Patent:
August 19, 2003
Assignee:
Semiconductor Energy Laboratory Co., Ltd.
Abstract: To provide a semiconductor device having a function equivalent to that of IGFET, an activation layer is formed by a crystal silicon film crystallized by using a catalyst element helping promote crystallization and a heating treatment is carried out in an atmosphere including a halogen element by which the catalyst element is removed, the activation layer processed by such steps is constituted by a peculiar crystal structure and according to the crystal structure, a rate of incommensurate bonds in respect of all of bonds at grain boundaries is 5 % or less (preferably, 0.3 % or less).
Type:
Grant
Filed:
October 17, 2000
Date of Patent:
August 19, 2003
Assignee:
Semiconductor Energy Laboratory Co., Ltd.
Abstract: An electronic circuit formed on an insulating substrate and having thin-film transistors (TFTs) comprising semiconductor layers. The thickness of the semiconductor layer is less than 1500 Å, e.g., between 100 and 750 Å. A first layer consisting mainly of titanium and nitrogen is formed on the semiconductor layer. A second layer consisting of aluminum is formed on top of the first layer. The first and second layers are patterned into conductive interconnects. The bottom surface of the second layer is substantially totally in intimate contact with the first layer. The interconnects have good contacts with the semiconductor layer.
Type:
Grant
Filed:
July 12, 2002
Date of Patent:
August 19, 2003
Assignee:
Semiconductor Energy Laboratory Co., Ltd.
Abstract: A matrix type liquid-crystal display unit includes: a plurality of pixel portions which are arranged in the form of a matrix; a plurality of signal lines through which a display signal is supplied to the pixel portions; a plurality of scanning lines through which a scanning signal is supplied to the pixel portions; a signal-line drive circuit for driving the signal lines; a scanning-line drive circuit for driving the scanning-lines; a plurality of first thin-film transistors that form the signal-line drive circuit; a plurality of second thin-film transistors that form the scanning-line drive circuit; and a threshold value control circuit being connected to the signal-line drive circuit and the scanning-line drive circuit, for commonly controlling threshold values of the first and second thin-film transistors.
Type:
Grant
Filed:
October 29, 2001
Date of Patent:
August 19, 2003
Assignee:
Semiconductor Energy Laboratory Co., Ltd.
Abstract: The present invention provides a luminescent apparatus having a bright, high-quality image. A reflecting surface-including electrode, and an EL element formed of an organic EL layer and a transparent electrode are provided on an insulator. As shown in FIG. 1, an auxiliary electrode 107 formed of a transparent conductive film is connected to the transparent electrode via a conductor. This structure enables a resistance value of the transparent electrode 104 to be substantially lowered, and a uniform voltage to be applied to the organic EL layer.
Type:
Grant
Filed:
May 8, 2001
Date of Patent:
August 19, 2003
Assignee:
Semiconductor Energy Laboratory Co., Ltd.
Abstract: An image display system comprises a first liquid crystal projector which projects a counterclockwise-rotating, circularly polarized light beam to form an image containing specific visual information on a screen and a second liquid crystal projector which projects a clockwise-rotating, circularly polarized light beam to form a white image on the same screen. When viewed with the naked eye, a combination of the two images projected on the screen appears totally white. A viewer wearing a dedicated viewing device equipped with an optical filter which allows counterclockwise-rotating, circularly polarized light to pass through can selectively see the image projected by the first liquid crystal projector.
Type:
Grant
Filed:
October 15, 1996
Date of Patent:
August 19, 2003
Assignee:
Semiconductor Energy Laboratory Co., Ltd.
Inventors:
Shunpei Yamazaki, Yoshiharu Hirakata, Jun Koyama, Satoshi Teramoto
Abstract: It is considered that in the fabricating steps of a TFT substrate, a color filter layer is prepared at the same alignment accuracy. However, since the heat resistance temperature is about 200° C., it could not withstand the process temperature of about 450° C. in the TFT.
Type:
Application
Filed:
February 4, 2003
Publication date:
August 14, 2003
Applicant:
Semiconductor Energy Laboratory Co., Ltd.
Abstract: There is provided a structure for reducing optical loss in an optical apparatus (homogenizer) for making the intensity distribution of a laser beam uniform.
Type:
Application
Filed:
February 24, 2003
Publication date:
August 14, 2003
Applicant:
Semiconductor Energy Laboratory Co. Ltd., a Japan corporation
Abstract: Each region, which should be left on a substrate after patterning, of a semiconductor film is grasped in accordance with a mask. Then, each region to be scanned with laser light is determined so that at least the region to be obtained through the patterning is crystallized, and a beam spot is made to hit the region to be scanned, thereby partially crystallizing the semiconductor film. Each portion with low output energy of the beam spot is shielded by a slit. In the present invention, the laser light is not scanned and irradiated onto the entire surface of the semiconductor film but is scanned such that at least each indispensable portion is crystallized to a minimum. With the construction described above, it becomes possible to save time taken to irradiate the laser light onto each portion to be removed through the patterning after the crystallization of the semiconductor film.
Type:
Application
Filed:
November 27, 2002
Publication date:
August 14, 2003
Applicant:
SEMICONDUCTOR ENERGY LABORATORY CO., LTD.
Abstract: A data holding control signal for each data line is supplied to a plurality of source followers that are connected together in parallel. The parallel-connected source followers are a combination of at least one first follower that is illuminated with laser light only once and at least one second follower that is illuminated twice. A width of the laser light illumination for crystallization is equal to a pitch of the source followers multiplied by an integer that is not less than 3.
Type:
Application
Filed:
February 27, 2003
Publication date:
August 14, 2003
Applicant:
Semiconductor Energy Laboratory Co., Ltd.
Abstract: To a provide a method of forming a layered film of a silicon nitride film and a silicon oxide film on a glass substrate in a short time without requiring a plurality of film deposition chambers. In a thin film transistor, a layered film including a silicon nitride oxide film (12) is formed between a semiconductor layer (13) and a substrate (11) using the same chamber. The silicon nitride oxide film has a continuously changing composition ration of nitrogen or oxygen. An electric characteristic of the TFT is thus improved.
Type:
Application
Filed:
February 19, 2003
Publication date:
August 14, 2003
Applicant:
Semiconductor Energy Laboratory Co., Ltd.