JP2002357847A - Active matrix substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the increase of costs caused by the increase of masks, the increase of stages and the increase of materials and to reduce yield loss caused by dust and the like by attaining the formation of a contact hole and rugged pattern in an active matrix substrate in one photolithographic stage. SOLUTION: In the photolithographic stage, insulation resin having a prescribed size is mixed in photosensitive insulation resin and the photosensitive insulation resin in which the insulation resin is mixed is applied in the entire surface of the substrate and pre-baked and then only the area of the contact hole is exposed. The contact hole is pierced by the development, the insulation resin in the non-exposed area except the area of the contact hole is not dissolved in developing liquid to be left as it is and the other non-disposed area is dissolved at a slower speed compared with that of the disposed area to form the rugged pattern.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an active matrix liquid crystal display device used for OA, AV and the like, and a liquid crystal display device.

[0002]

2. Description of the Related Art As shown in FIG. 1A, a conventional active matrix substrate has a gate electrode formed on an insulator substrate, a first insulating film formed, a transistor region formed, and a source / drain electrode formed thereon. Is formed, a second insulating film is formed, finally a thin film transistor (TFT) is formed, a photosensitive insulating resin (planarizing resin) is applied to flatten the thin film transistor and increase an aperture ratio, and contact is performed by photolithography. A pattern for obtaining holes is formed, and a hole similar to a contact hole is formed as a base for forming unevenness, and then a hole for forming unevenness is formed by a similar method to secure optimal scattering characteristics. The photosensitive insulating resin is filled to some extent, only the contact hole is exposed and developed, a hole is formed, and a pixel electrode is formed thereon. He had been with the array. Here, the reason why the unevenness has to be filled is that the unevenness pattern formed in the first step has the shape shown in FIG. 1B, but if the reflective electrode is formed in this state, the incident angle In some cases, the reflected light does not return at all (large tilt angle), resulting in a very dark liquid crystal panel with poor light use efficiency. In order to solve this problem, as a first method, in the above conventional example, a photosensitive insulating resin is applied again,
By filling the unevenness to reduce the inclination angle (〜１０10 °), it is possible to obtain the maximum amount of light returning to the front (that is, bright and wide viewing angle) while securing the diffusivity.

As a second method, as shown in FIG. 2, at the time of forming the first concavo-convex pattern, the conditions of the photolithography (UV irradiation) are optimized, or the pattern of the photomask is reduced to the exposure limit to “blurr”. Thus, there has been a method in which the process of filling the irregularities is simplified by stopping the bottoms of the irregularities in the middle of the photosensitive insulating resin, thereby obtaining similar characteristics.

[0004]

However, in the first method of the above-mentioned conventional example, it is necessary to perform the photosensitive insulating resin coating process twice, which requires an increase in the number of masks, the number of steps, the number of materials, and the cost. There were issues such as yield loss. Further, in the second method, the exposure is stopped halfway, and there is a problem that the in-plane variation of the reflection characteristic or the variation between lots increases depending on the state of the apparatus (exposure illuminance and in-plane distribution of the baking temperature). Was.

[0005]

According to the present invention, there is provided a method for forming a concavo-convex pattern on an active matrix substrate according to the present invention, wherein a predetermined size of insulating resin is contained in a photosensitive insulating resin in a first photolithography step. And then apply a photosensitive insulating resin mixed with this insulating resin to the entire surface of the substrate, perform pre-baking, expose only the contact hole area, make holes in the contact holes by development, and apply photosensitive insulating resin to the other areas. Is left undissolved in the developer, and is dissolved in the other areas with the developer.
Since unevenness can be formed in a single photolithography step, and at the same time, contacts and holes can be formed, an excellent liquid crystal display device that solves the above problems can be realized.

[0006]

(Embodiment 1) Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG.
FIG. 1A is a cross-sectional view of Conventional Example 1, and FIG.
2 is a cross-sectional view of Conventional Example 2 after the photosensitive insulating resin pattern is formed. FIG. 3 is a sectional view of an embodiment of the present invention.
FIG. 4 is a plan view of an embodiment of the present invention, and FIGS.

Hereinafter, description will be given according to the manufacturing process. First, a metal thin film (for example, Al) is deposited on a transparent insulating substrate 1 made of a glass substrate or the like by sputtering, then a resist pattern for obtaining a gate pattern is formed, and a gate is formed by photolithography and etching. Electrode 2
To form Next, as the gate insulating film 3, for example, SiNx by a plasma CVD method, and as the semiconductor layer 4, a-S
The n + a-Si, which is the ohmic contact layer 5 for satisfactorily contacting the i, source and drain electrodes, is continuously deposited at 3000, 2000 and 500, respectively. Next, the SiNx, a-Si, and n + a-Si are collectively patterned into an island shape by photolithography and etching. Next, a metal (for example, Ti) serving as a source electrode is deposited on the entire surface by a sputtering method, and the source and drain electrode patterns 6 are formed by photolithography.
7, and a thin film transistor array substrate is completed (FIG. 5). Next, the unevenness forming step of the present invention is performed.

First, a photosensitive insulating resin 8 in which an insulating resin 9 having a diameter of 3 μm is mixed on the thin film transistor array substrate is applied to, for example, the entire surface of a 4 μm substrate (FIG. 6). Next, after performing pre-baking, exposure and development with a photomask for obtaining a contact hole are performed, and the contact hole portion exposed by the photomask is dissolved by a developing solution, and a contact hole is formed. Although it has not been exposed, it dissolves in the developer at a slower rate than the exposed area, and the insulating resin hardly dissolves in the developer, so by controlling the mixing ratio of the insulating resin and the development conditions An uneven pattern is formed by the photosensitive insulating resin and the insulating resin (FIG. 7). Next, a reflective electrode metal film 10 (for example, Al) is deposited on the entire surface by a sputtering method, a resist for forming a pixel electrode is applied, and after the resist pattern is formed, an unnecessary reflective electrode material is etched with an etchant (for example, a phosphoric acid mixture) Etching with pixel electrode
The active matrix substrate is completed (FIGS. 3 and 4). According to this embodiment, the formation of the concavo-convex pattern for obtaining a bright and wide-viewing-angle reflection characteristic can be performed only once in the conventional photolithography process using a flattening resin. Cost and yield loss can be reduced.

As described above, according to the embodiment of the present invention, an insulating resin having a predetermined size is mixed in the photosensitive insulating resin in the unevenness forming step, and the photosensitive insulating resin containing the insulating resin is mixed with the substrate. Apply to the entire surface, pre-bake, expose only the contact hole area, develop contact holes by development, and in the other unexposed areas, the insulating resin remains undissolved in the developing solution, and the other areas By dissolving in one step, unevenness can be formed in one photolithography step, and contact and holes can be formed at the same time.
It is possible to reduce costs and yield loss by reducing the number of processes.

In the first embodiment of the present invention, the gate metal 2
Is Al, but may be an alloy obtained by adding a high melting point metal to Ti, Cr, Cu, MoW or Al, or a laminated structure of these metals. Further, the TFT array may be a TFT array made of low-temperature polysilicon. Further, although the pixel electrode 10 is made of Al, it may be made of an alloy obtained by adding a high melting point metal such as Ta, Mo, W or the like to Al, a silver alloy, or a laminated structure of these metals.

[0011]

As described above, according to the present invention, in the step of forming a concavo-convex pattern, an insulating resin having a predetermined size is mixed in the photosensitive insulating resin, and the photosensitive insulating resin mixed with the insulating resin is coated on the entire surface of the substrate. Coating, pre-baking, exposure treatment only in contact hole area, contact hole is opened by development, and in other unexposed areas, insulating resin remains undissolved in developer, other areas are dissolved by developer As a result, unevenness can be formed in a single photolithography process, and a contact hole can be formed at the same time.
An excellent liquid crystal display device that can reduce the yield loss can be realized.

[Brief description of the drawings]

FIG. 1A is a cross-sectional view of an active matrix substrate in a first conventional example. FIG. 1B is a cross-sectional view after a first planarization film forming step in a first conventional example.

FIG. 2 is a process chart of forming concavities and convexities in the form of Conventional Example 2.

FIG. 3 is a cross-sectional view of an active matrix substrate according to an embodiment of the present invention.

FIG. 4 is a plan view of an active matrix substrate according to an embodiment of the present invention.

FIG. 5 is an explanatory diagram of a process for producing an active matrix substrate of the present invention.

FIG. 6 is an explanatory diagram of a process for producing an active matrix substrate of the present invention.

FIG. 7 is an explanatory view of a process for producing an active matrix substrate of the present invention.

[Explanation of symbols]

 Reference Signs List 1 transparent insulating substrate 2 gate electrode 3 SiNx 4 a-Si 5 n + a-Si 6 source electrode 7 drain electrode 8 photosensitive insulating resin 9 insulating resin 10 metal film for reflective electrode 21 pixel electrode 22 insulating resin 23 contact hole 24 gate Wiring 25 Source wiring

Continued on the front page F-term (reference) 2H042 BA03 BA15 BA20 2H091 FA14Z GA01 GA13 LA30 2H092 GA29 JA24 JA32 JA41 MA05 MA08 MA13 MA17 MA29 NA26 PA01 5F110 AA16 AA30 BB01 CC07 DD02 EE02 EE03 EE04 EE06 FF14 GG03 FF03 HK16 HK21 HK33 HK35 HL03 HL06 HL11 HL23 NN04 NN27 NN72 QQ02 QQ09

Claims (7)

[Claims] 1. A thin film transistor (TFT) provided in a matrix on an insulating substrate, an insulating film formed on the thin film transistor, and a reflective display electrode provided on the insulating film on the thin film transistor. A thin film transistor substrate in which the reflective display electrode is connected to a drain electrode or a gate electrode of a thin film transistor via a contact hole formed in the insulating film layer, wherein the insulating film is a photosensitive insulating resin; An active matrix substrate, wherein irregularities are formed on the surface of the insulating film. 2. The active matrix substrate according to claim 1, wherein an insulating resin having a predetermined shape is mixed in said photosensitive insulating resin. 3. The uneven pattern formed on the photosensitive resin, wherein the insulating resin mixed in the photosensitive resin in the developing step after depositing the photosensitive insulating resin mixed with the insulating resin is convex, 2. The active matrix substrate according to claim 1, wherein the region where the insulating resin is not present becomes concave by being reduced by the developer. 4. The insulating resin according to claim 2, wherein the insulating resin is spherical or columnar and has a diameter of 2 to 4 μm. 5. The insulating resin according to claim 2, wherein the insulating resin hardly dissolves in a developer. 6. The active matrix substrate according to claim 1, wherein said contact hole is formed by UV exposure and development using a photomask. 7. The method according to claim 7, wherein the reflective electrode is Al or A.
2. The method for manufacturing an active matrix substrate according to claim 1, wherein the main component is an alloy containing l as a main component, silver, an alloy containing silver as a main component, or a laminated structure of these metals.