|Publication number||USRE41632 E1|
|Application number||US 11/984,431|
|Publication date||Sep 7, 2010|
|Priority date||May 27, 1999|
|Also published as||US6337284, USRE40028|
|Publication number||11984431, 984431, US RE41632 E1, US RE41632E1, US-E1-RE41632, USRE41632 E1, USRE41632E1|
|Inventors||Kwangjo Hwang, Changwook Han|
|Original Assignee||Lg Display Co., Ltd.|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (19), Non-Patent Citations (2), Referenced by (1), Classifications (25), Legal Events (1)|
|External Links: USPTO, USPTO Assignment, Espacenet|
More than one reissue application has been filed for the reissue of U.S. Pat. No. 6,337,284. The reissue applications are application Ser. No. 11/984,431 which is a Divisional Reissue Application of Reissue U.S. patent application Ser. No. 10/752,486, filed on Jan. 7, 2004, now U.S. Pat. No. RE 40,028, which is a Reissue of U.S. patent application Ser. No. 09/580,590 now U.S. Pat. No. 6,337,284, which claims priority to Korean Patent Application No. 99- 19145, all of which are hereby incorporated by reference as if fully set forth herein.
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.
1. 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 insulating 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 76b 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 photomask (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.
An 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 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 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 from 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
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.
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|1||C.W. Kim et al., "A Novel Four-Mask-Count Process Architecture for TFT-LCDs," Society for Information Display International Symposium Digest of Technical Papers, vol. XXXI, Long Beach Convention Center, Long Beach, California, May 16-18, 2000, pp. 1006-1009.|
|2||Chang Wook Han et al., "A TFT Manufactured by 4 Masks Process with New Photolithography, " SID KPS, Proceedings of the 18th International Display Research Conference, Asia Display '98, Sep. 28-Oct. 1, 1988, Seoul, Korea.|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US20120105781 *||May 3, 2012||Ah-Ram Lee||Liquid crystal display device and manufacturing method thereof|
|U.S. Classification||349/43, 257/247, 438/725, 438/719, 438/158, 438/718, 438/710, 430/30, 257/59|
|International Classification||H01L21/77, H01L21/84, G02F1/1362, H01L21/3213, H01L21/311, H01L21/336, H01L31/00, H01L21/302, G02F1/136|
|Cooperative Classification||G02F1/136227, G02F2001/136231, H01L29/66765, H01L27/1214, H01L27/1288|
|European Classification||H01L29/66M6T6F15A3, H01L27/12T|