Liquid crystal display device and method of manufacturing the same
The present invention discloses a method of manufacturing a liquid crystal display device including a first photolithography process forming a gate electrode on a substrate; a second photolithography process including: a) depositing sequentially a gate insulating layer, first and second semiconductor layers, and a metal layer; b) applying a first photoresist on the metal layer; c) aligning a first photo mask with the substrate; d) light exposing and developing the first photoresist to produce a first photoresist pattern; e) etching the metal layer using a first etchant, the first etchant ashing the first photoresist pattern on a predetermined portion of the metal layer to produce a second photoresist pattern, thereby exposing the predetermined portion of the metal layer; and f) etching the gate insulating layer, the first and second semiconductor layer, and the predetermined portion of the metal layer using a second etchant according to the second photoresist pattern to form source and drain electrodes, an ohmic contact layer, and an active area; a third photolithography process forming a passivation film and a contact hole; and a fourth photolithography process forming a pixel electrode connecting with the drain electrode through the contact hole.
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This application claims the benefit of Korean Patent Application No. 1999-19145, filed on May 27, 1999, under 35U.S.C. §119, the entirety of which is hereby incorporated by reference.
BACKGROUND OF THE INVENTION1. Field of the Invention
The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device fabricated through four photolithography processes and a method of fabricating the same.
2. Description of the Related Art
As shown in
The LCD device described above is completed through five photolithography processes.
Hereinafter, a method of fabricating the conventional LCD device will be explained in detail.
First, a gate electrode 60a shown in
In the first photolithography process, a metal layer (not shown) of Mo or Cr is deposited on the transparent substrate 10 and then a photoresist is applied on the metal layer. Then, a first photo-mask (not shown) is located over the substrate 10, and light exposure and developing processes are performed to etch the metal layer so that the gate electrode 60a is formed. Finally, the photoresist remaining on the metal layer is removed, leaving the gate electrode 60a on transparent substrate 10 as shown in FIG. 2A.
Second, a gate insulting layer 50, the a-Si layer 80a, and a n+ a-Si layer 80b shown in
As shown in
Third, the source electrode 70a and the drain electrode 70b shown in
As shown in
Fourth, the passivation layer 55 having the contact hole 30 shown in
An inorganic material such as a nitride or oxide of silicon (SiNx or SiOx, respectively) or an organic material such as bis-benzocyclobutene (BCB) is deposited on the source electrode 70a and the drain electrode 70b. After that, the positive type photoresist (not shown) is applied, and then light exposure and developing processes are performed using a fourth photo-mask (not shown) to form a photoresist pattern. Then, the passivation layer 55 is formed through an etching process. After the etching process, the photoresist pattern remaining on the passivation layer 55 is removed.
Fifth, the pixel electrode 40 to be connected to the drain electrode 70b shown in
A metal layer such as indium tin oxide (ITO) is deposited on the passivation layer 55. After that, the positive type photoresist (not shown) is applied, and then light exposure and developing processes are performed using a fifth photo-mask (not shown), thereby forming a photoresist pattern. In accordance with the photoresist pattern, the metal layer is etched so that the pixel electrode 40 is formed. After the etching process, the photoresist pattern remaining on the pixel electrode 40 is removed.
The photolithography process described above includes the steps of: cleaning a substrate; applying a photoresist; soft-baking the photoresist; aligning a photo-mask; light-exposing the photoresist; developing the photoresist; inspecting the array substrate; hard-baking the photoresist; etching a portion that the photoresist does not cover; inspecting the array substrate; and removing the photoresist.
Since the photolithography process includes the complex steps described above, as the number of photolithography processes increases, the inferiority rate become greater, leading to a low yield. In other words, reliability of the manufacturing process varies inversely proportional to the number of photolithography processes performed.
SUMMARY OF THE INVENTIONAn object of the present invention is to provide a liquid crystal display device fabricated through four photolithography processes.
Another object of the present invention is to increase yield and to reduce the production cost of TFT fabrication.
To achieve the above objects, the present invention provides a method of manufacturing a liquid crystal display device including a first photolithography process forming a gate electrode on a substrate; a second photolithography process including: a) depositing sequentially a gate insulating layer, first and second semiconductor layers, and a metal layer; b) applying a first photoresist on the metal layer; c) aligning a first photo mask with the substrate; d) light exposing and developing the first photoresist to produce a first photoresist pattern; e) etching the metal layer using a first enchant, the first etchant ashing the first photoresist pattern on a predetermined portion of the metal layer to produce a second photoresist pattern, thereby exposing the predetermined portion of the metal layer; and f) etching the gate insulating layer, the first and second semiconductor layer, and the predetermined portion of the metal layer using a second etchant according to the second photoresist pattern to form source and drain electrodes, an ohmic contact layer, and an active area; a third photolithography process forming a passivation film and a contact hole; and a fourth photolithography process forming a pixel electrode contacting with the drain electrode through the contact hole.
The first etchant contains Cl2/O2 gas and the second etchant contains SF6/HCl or SF6/H2/Cl2 gas. The source and drain electrodes are made of a metal selected form a group consisting of Cr, Mo, Al, and Al alloy, and the first semiconductor layer comprises an amorphous silicon and the second semiconductor layer comprises an amorphous silicon doped with n-type impurity.
For a more complete understanding of the present invention and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which like reference numerals denote like parts, and in which:
Reference will now be made in detail to the preferred embodiment of the present invention, example of which is illustrated in the accompanying drawings.
As shown in
Referring to
In a second photolithography process, as shown in
Further, as shown in
Continually, as shown in
And then, as shown in
Further, the exposed portion of the metal layer 170 and the central portion of the n+ a-Si layer 80b corresponding to the exposed portion of the metal layer 170 are etched by a third etchant preferably containing Cl2/O2 gas, thereby forming an ohmic contact layer, and source and drain electrodes 70a and 70b. At this time, the photoresist pattern 88a functions as a mask.
Subsequently, as shown in
In a third photolithography process, as shown in
In a fourth photolithography process, as shown in
Accordingly, the substantially important components of liquid crystal display device according to the preferred embodiment of the present invention are completed by four photolithography processes described above.
In the present invention, since the a-Si layer 80a, the n+ a-Si layer 80b and the source and drain electrodes are simultaneously formed through the same photolithography process, that is, by the diffraction light exposure using the second photo-mask, it is possible to manufacture the LCD device through the four lithography processes, thereby increasing the yield and reducing the production cost by decreasing the inferiority rate due to many photolithography processes.
It is further understood by those skilled in the art that the foregoing description is a preferred embodiment of the disclosed device and that various changes and modification may be made in the invention without departing from the spirit and scope thereof.
Claims
1. A method of manufacturing a liquid crystal display device, comprising:
- a first photolithography process forming a gate electrode on a substrate;
- a second photolithography process including: a) depositing sequentially a gate insulating layer, a semiconductor layer, and a metal layer; b) applying a first photoresist on the metal layer; c) aligning a first photo mask with the substrate; d) light exposing and developing the first photoresist to produce a first photoresist pattern; e) etching the metal layer using a first etchant, the first etchant ashing the first photoresist pattern on a portion of the metal layer to produce a second photoresist pattern, thereby exposing the portion of the metal layer; and f) etching the gate insulating layer, the semiconductor layer, and the portion of the metal layer using a second etchant according to the second photoresist pattern to form source and drain electrodes, an ohmic contact layer, and an active area;
- a third photolithography process forming a passivation film and a contact hole; and
- a fourth photolithography process forming a pixel electrode connecting with the drain electrode through the contact hole.
2. The method of claim 1, wherein the first etchant includes Cl2/O2 gas.
3. The method of claim 2, wherein the second etchant includes SF6/HCl gas.
4. The method of claim 2, wherein the second etchant includes SF6/H2/Cl2 gas.
5. The method of claim 1, wherein the semiconductor layer includes first and second semiconductor layers.
6. The method of claim 5, wherein the first semiconductor layer includes amorphous silicon.
7. The method of claim 5, wherein the second semiconductor layer includes doped amorphous silicon.
8. The method of claim 1, wherein the source and drain electrodes are made of a metal selected from a group consisting of Cr, Mo, Al, and Al alloy.
9. The method of claim 8, wherein the semiconductor layer includes first and second semiconductor layers.
10. The method of claim 9, wherein the first semiconductor layer includes amorphous silicon.
11. The method of claim 9, wherein the second semiconductor layer includes doped amorphous silicon.
12. The method of claim 1, wherein the pixel electrode includes indium tin oxide.
13. The method of claim 12, wherein the semiconductor layer includes first and second semiconductor layers.
14. The method of claim 13, first semiconductor layer includes amorphous silicon.
15. The method of claim 13, wherein the second semiconductor layer includes doped amorphous silicon.
16. A method of manufacturing a thin film transistor of a liquid crystal display device, comprising:
- forming a gate electrode on substrate; and
- forming a gate insulating layer, a semiconductor layer and source and drain electrodes using a photolithography process including:
- forming a gate insulating layer a semiconductor layer, and a metal layer;
- forming a photoresist on the metal layer;
- light exposing and developing the photoresist to produce a first photoresist pattern, wherein the first photoresist pattern includes a central portion having a first thickness and adjacent side portions having a second thickness, the first thickness being smaller than the second thickness;
- selectively removing the metal layer using the first photoresist pattern;
- removing the central portion of the first photoresist pattern to form a second photoresist pattern;
- selectively removing the semiconductor layer using the second photoresist pattern;
- selectively removing the metal layer corresponding to the central portion of the photoresist pattern; and
- selectively removing the semiconductor layer corresponding to the central portion of the photoresist pattern.
17. The method of claim 16, wherein light exposing and developing the photoresist to produce the photoresist first pattern includes using a diffraction light exposure technique.
18. The method of claim 16, wherein the metal layer is selectively removed using a dry etch technique.
19. The method of claim 18, wherein the dry etch technique uses a gas including Cl2/O2 gas.
20. The method of claim 16, wherein the semiconductor layer is selectively removed using a dry etch technique.
21. The method of claim 20, wherein the dry etch technique uses a gas including fluorine and chlorine.
22. The method of claim 21, wherein the gas includes SF6/HCl.
23. The method of claim 21 wherein the gas includes SF6/H2/Cl2.
24. The method of claim 16, wherein the semiconductor layer includes first and second semiconductor layers.
25. The method of claim 24, wherein the first semiconductor layer includes amorphous silicon.
26. The method of claim 24, wherein the second semiconductor layer includes doped amorphous silicon.
27. The method of claim 16, wherein the source and drain electrodes are made of a metal selected from the group consisting of Cr, Mo, Al, and Al alloy.
28. The method of claim 16, wherein removing the central portion of the first photoresist pattern exposes the metal layer.
29. A method of manufacturing a thin film transistor of a liquid crystal display device, comprising:
- forming a gate electrode on a substrate;
- forming a gate insulating layer, a first semiconductor layer, a second semiconductor layer and source and drain electrodes using a photolithography process including:
- forming a gate insulating layer, a first semiconductor layer, a second semiconductor layer and a metal layer;
- forming a photoresist on the metal layer;
- positioning a photo mask above the substrate;
- light exposing and developing the photoresist to produce a photoresist pattern, wherein the photoresist pattern includes a central portion having a first thickness and adjacent side portions having a second thickness, the first thickness being smaller than the second thickness;
- selectively removing the metal layer using the photoresist pattern;
- selectively removing the first and second semiconductor layers;
- selectively removing the metal layer beneath the central portion of the photoresist pattern having the first thickness to separate the metal layer into a first part spaced from a second part, the first part corresponding to the source electrode and the second part corresponding to the drain electrode; and
- selectively removing the first semiconductor layer corresponding to the space between the first and second parts of the metal layer.
30. The method of claim 29, wherein the central portion of the photoresist is removed prior to selectively removing the first and second semiconductor layers.
31. A method of manufacturing a liquid crystal display device, comprising:
- forming a thin film transistor and a pixel electrode coupled to the thin film transistor; and
- forming the thin film transistor including:
- forming a gate electrode on a substrate;
- forming a gate insulating layer, a semiconductor layer and source and drain electrodes using a photolithography process including:
- forming a gate insulating layer, a semiconductor layer, and a metal layer;
- forming a photoresist on the metal layer;
- positioning a photo mask above the substrate;
- light exposing and developing the photoresist to produce a photoresist pattern, wherein the photoresist pattern includes a central portion having a first thickness and a side portion having a second thickness, the first thickness being smaller than the second thickness;
- selectively removing the metal layer using the photoresist pattern;
- removing the central portion of the photoresist pattern having a first thickness;
- selectively removing the semiconductor layer;
- selectively removing the metal layer corresponding to the central portion of the photoresist pattern; and
- selectively removing the semiconductor layer corresponding to the central portion of the photoresist pattern.
32. The method of claim 31, further comprising forming a passivation film having a contact hole over the source and drain electrodes, wherein the pixel electrode is formed on the passivation layer and contacting the drain electrode through the contact hole.
33. The method of claim 31, wherein the pixel electrode directly contacts the drain electrode.
34. The method of claim 31, wherein the pixel electrode includes indium tin oxide.
35. A method of manufacturing a liquid crystal display device, comprising:
- forming a thin film transistor and a pixel electrode coupled to the thin film transistor;
- forming the thin film transistor including:
- forming a gate electrode on a substrate;
- forming a gate insulating layer, a first semiconductor layer, a second semiconductor layer and a metal layer;
- forming a photoresist on the metal layer;
- positioning a photo mask above the substrate;
- light exposing and developing the photoresist to produce a photoresist pattern, wherein the photoresist pattern includes a central portion having a first thickness and a side portion having a second thickness, the first thickness being smaller than the second thickness;
- selectively removing the metal layer using the photoresist pattern;
- selectively removing the first and second semiconductor layers;
- selectively removing the metal layer beneath the central portion of the photoresist pattern having the first thickness to separate the metal layer into a first part spaced from a second part, the first part corresponding to the source electrode and the second part corresponding to the drain electrode; and
- selectively removing the first semiconductor layer corresponding to the space between the first and second parts of the metal layer.
36. The method of claim 35, wherein the central portion of the photoresist is removed prior to selectively removing the first and second semiconductor layers.
37. A method of manufacturing a liquid crystal display device, comprising:
- forming a gate electrode on a substrate;
- forming a gate insulating layer, a semiconductor layer and source and drain electrodes using a photolithography process including:
- forming a gate insulating layer, a semiconductor layer, and a metal layer;
- forming a photoresist on the metal layer;
- positioning a photo mask above the substrate;
- light exposing and developing the photoresist to produce a photoresist pattern, wherein the photoresist pattern includes a central portion having a first thickness and adjacent side portions having a second thickness, the first thickness being smaller than the second thickness;
- selectively removing the metal layer using the photoresist pattern;
- removing the central portion of the photoresist pattern having the first thickness to expose the metal layer;
- selectively removing the semiconductor layer;
- selectively removing the metal layer corresponding to the central portion of the photoresist pattern;
- selectively removing the semiconductor layer corresponding to the central portion of the photoresist pattern;
- forming a passivation film having a contact hole over the source and drain electrodes; and
- forming a pixel electrode contacting the drain electrode through the contact hole.
38. A method of manufacturing a thin film transistor of a liquid crystal display device, comprising:
- forming a gate electrode on a substrate;
- forming a gate insulating layer, a semiconductor layer, and a metal layer over the gate electrode;
- forming a photoresist over the metal layer, the photoresist including a central portion having a first thickness and a side portion having a second thickness, the first thickness being smaller than the second thickness; and
- selectively removing the metal layer and the semiconductor layer including portions of the metal layer below the central portion of the photoresist to form source and drain electrodes and a channel.
39. The method of claim 38, wherein the semiconductor layer includes a first semiconductor layer and a second semiconductor layer on the first semiconductor layer.
40. The method of claim 39, further comprising selectively removing the second semiconductor layer corresponding to the central portion of the photoresist.
41. The method of claim 39, wherein the first semiconductor layer includes amorphous silicon and the second semiconductor layer includes doped amorphous silicon.
42. The method of claim 38, wherein the metal layer is selectively removed using a dry etch technique.
43. The method of claim 42, wherein the dry etch technique uses a gas including Cl2/O2 gas.
44. The method of claim 38, wherein the semiconductor layer is selectively removed using a dry etch technique.
45. The method of claim 44, wherein the dry etch technique uses a gas including fluorine and chlorine.
46. The method of claim 45, wherein the gas includes SF6/HCl.
47. The method of claim 45, wherein the gas includes SF6/H2/Cl2.
48. The method of claim 38, wherein the source and drain electrodes are made of a metal selected from the group consisting of Cr, Mo, Al, and Al alloy.
49. A method of manufacturing a thin film transistor of a liquid crystal display device, comprising:
- forming a gate electrode on a substrate;
- forming a gate insulating layer, a first semiconductor layer, a second semiconductor layer and source and drain electrodes using a photolithography process including:
- sequentially forming the gate insulating layer, the first semiconductor layer, the second semiconductor layer and the metal layer;
- forming a photoresist on the metal layer;
- positioning a photo mask above the substrate;
- light exposing and developing the photoresist to produce a photoresist pattern, wherein the photoresist pattern includes a central portion having a first thickness and adjacent side portions having a second thickness, the first thickness being smaller than the second thickness;
- selectively removing the metal layer using the photoresist pattern;
- selectively removing the first and second semiconductor layers;
- selectively removing a portion of the metal layer beneath the central portion of the photoresist pattern to separate the metal layer into a first part spaced from a second part, the first part corresponding to the source electrode and the second part corresponding to the drain electrode; and
- selectively removing the first semiconductor layer corresponding to the space between the first and second parts of the metal layer.
50. The method of claim 49, wherein the central portion of the photoresist is removed prior to selectively removing the first and second semiconductor layers.
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Type: Grant
Filed: Jan 7, 2004
Date of Patent: Jan 22, 2008
Assignee: LG. Philips LCD Co., Ltd. (Seoul)
Inventors: Kwangjo Hwang (Kyonggi-do), Changwook Han (Seoul)
Primary Examiner: Duy-Vu N. Deo
Attorney: McKenna Long & Aldridge LLP
Application Number: 10/752,486
International Classification: H01L 21/302 (20060101); H01L 21/461 (20060101);