JP2001067017A - Active matrix substrate manufacturing method and manufacturing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing an active matrix substrate, which eliminates a metallic glossy reflection characteristic at a pixel electrode, which is a problem in a conventional reflection type LCD, and dramatically improves display quality. . SOLUTION: In a manufacturing process for forming pixel electrodes connected to active elements in a matrix on an insulating film 4 covering active elements 2 and address wirings 3, the insulating film 4
In the forming step, the substrate coated with the photosensitive resin 4a is heated so that high-temperature portions and low-temperature portions having an area smaller than the size of the pixel electrode to be formed are alternately distributed, and the solvent 7 in the resin is removed. Allow to evaporate. At this time, irregularities occur on the resin surface, and irregularities also occur on the pixel electrodes formed thereon, thereby forming a diffusion surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an active matrix (hereinafter referred to as A) having an active element for each display pixel.
M) A method and apparatus for manufacturing a substrate.

[0002]

2. Description of the Related Art In recent years, AM type liquid crystal displays (hereinafter, LCDs) have been rapidly developed, and displays having a screen size of 10 inches or more have already been commercialized. In response to a demand for further power saving, the reflection type L
As the development of CDs has progressed, displays capable of displaying colors approaching the transmissive type have been commercialized. The AM-type LCD controls a potential of a pixel electrode by controlling an active element provided for each display pixel, and changes an optical characteristic of a liquid crystal to display a desired image.

A conventional example will be described below with reference to the drawings. FIG. 3 shows a cross-sectional structure of one pixel portion of a conventional AM substrate, and FIG. 4 shows a cross-sectional structure of each process from formation of an insulating film to before formation of a pixel electrode in a process of manufacturing the AM substrate. Things.

In FIG. 3, a conventional AM substrate is provided with an active element 2 and an address wiring 3 on an insulating substrate 1 such as glass, and an insulating film 4 is provided so as to cover the active element 2 and the address wiring 3. The pixel electrode 6 is connected to the active element 2 through an opening 5 formed in the film 4. Pixel electrode 6 and active element 2
In addition, since the signal line overlaps with the address line 3 via the insulating film 4, capacitive coupling occurs, and a signal to be applied to the pixel electrode changes due to interference from the signal of the active element 2 and the address line 3. In order to reduce this to an acceptable level or less, the thickness of the insulating film 4 is generally at least 2000 nm or more.

[0005] As shown in FIG. 4, in a conventional manufacturing process for forming an insulating film on an AM substrate, first, an insulating substrate 1 provided with an active element 2 and an address wiring 3 is provided.
Then, a positive photosensitive resin 4a diluted with a solvent is applied so as to cover the active element 2 and the address wiring 3 (application step). Next, the substrate coated with the photosensitive resin 4a is placed on a baking apparatus including a hot plate 8 with a built-in heater, and heated to evaporate the solvent 7 (first baking step). Next, the substrate subjected to the first baking step is irradiated with ultraviolet rays 10 using a predetermined mask 9 for exposing only a necessary opening such as the opening 5 in order to connect with the active element 2. Then, the photosensitive resin 4a is exposed (exposure step). Then, a chemical solution process (developing process) such as a developing solution is performed on the exposed substrate.
The resin in the exposed portion is dissolved to form a predetermined opening 5. Finally, the insulating film 4 is formed by performing the second baking process using the same baking apparatus used in the first baking process and curing the resin.

[0006] In the AM type LCD which has already been commercialized,
Normally, a photosensitive resin is used for the insulating film 4, and the formation of the insulating film 4 and the predetermined opening 5 are simultaneously formed by a coating step, a first baking step, an exposure step, a developing step, and a second baking step. . Generally, in the baking process, a baking apparatus including a plate having a built-in heater such as a hot plate is used, and a heating process is often performed by placing an AM substrate on the plate. Further, this plate is provided with a suction groove for fixing the AM substrate, a protrusion for facilitating removal of the AM substrate, and the like.

[0007]

In such a manufacturing method and a manufacturing apparatus, since an insulating film made of resin is formed almost flat, a reflection type liquid crystal display device is formed by using an AM substrate formed by this method. With this configuration, the surface of the reflective electrode, which is a pixel electrode, is almost mirror-finished, and the reflected light is mirror-reflected light. Characteristics
The display quality will be significantly degraded.

In order to avoid this problem, fine irregularities are formed on the pixel electrode surface so that the pixel electrode surface is changed from a mirror surface state in which the pixel electrode surface is reflected in one direction to a diffuse reflection surface state in which the pixel electrode surface is reflected in almost all directions. There is a need to.

As a method of forming irregularities on the pixel electrode surface,
Using a photosensitive resin, a coating process, a first baking process, an exposing process, a developing process, and a second baking process are used to form irregularities in a region where a reflective electrode is to be formed. In this method, an insulating film and a predetermined opening are simultaneously formed so as to cover the irregularities formed in the above, and a pixel electrode is formed thereon.

With this configuration, the yield of the LCD is reduced due to the increase in the number of steps, and the cost is increased by using an expensive material such as a photosensitive resin a plurality of times.

As another method of forming irregularities, it is also possible to form irregularities of a predetermined shape using a material for forming an active element and an address wiring under a pixel electrode at the same time as forming an active element and an address wiring. .

However, in this case, the film thickness of the material forming the active element and the address wiring is about several hundreds nm, and when a photosensitive resin having a thickness of 2000 nm or more is applied, it is almost flattened. Will be gone. In order to improve this, it is necessary to increase the thickness of the material. However, the material for forming the active element and the address wiring is generally made of an inorganic material, and an expensive vacuum film forming apparatus is used for the formation. In addition, since the film formation speed is low, a plurality of expensive devices are required to form a film of 1000 nm or more and secure the productivity, resulting in a significant increase in cost.

Further, when a film having a thickness of 1000 nm or more is processed into a predetermined shape, the processing accuracy is deteriorated by the wet etching method. Therefore, in order to secure the processing accuracy, a dry etching method is generally used. .
However, the dry etching system is more expensive than the wet etching system, and the processing speed is not so high. Therefore, as with the previous vacuum film forming system, an expensive system is required to secure productivity. , A large increase in cost is required.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a relatively simple method for manufacturing an active matrix substrate having good display quality and high visibility without having metallic glossy display characteristics. An object is to provide a manufacturing apparatus at low cost.

[0015]

In order to achieve the above object, a method of manufacturing an active matrix substrate according to the present invention comprises the steps of forming an active element and an address wiring on an insulating substrate; Forming an insulating film so as to cover the active element, and forming a matrix of pixel electrodes connected to the active elements through openings formed in the insulating film, the method comprising: The insulating film forming step includes a step of applying a photosensitive resin diluted with a solvent so as to cover the active element and the address wiring, and a step of forming the substrate coated with the photosensitive resin smaller than the size of the pixel electrode to be formed. A first baking step of heating so that hot and cold parts of the area are alternately distributed and evaporating the solvent; Selectively exposing the evaporated photosensitive resin, developed is for the exposure and development step of forming an opening, characterized by comprising a second baking step of curing the photosensitive resin.

As the photosensitive resin, an acrylic resin can be used. Further, the first baking step of heating so that the high-temperature portion and the low-temperature portion are alternately distributed is performed on a hot plate in which the high-temperature portion and the low-temperature portion having an area smaller than the size of the pixel electrode to be formed are alternately distributed. Then, the substrate coated with the photosensitive resin is placed and heated.

As a hot plate in which high-temperature portions and low-temperature portions are alternately distributed, fine irregularities are provided on the surface of the plate.
When a substrate is mounted thereon, a difference may be caused in heat transfer to the substrate.

According to the present invention, fine irregularities can be formed on the insulating film below the pixel electrode by using the above-described method and apparatus. A reflection type AM substrate and a reflection type AM having high display performance and excellent display performance which can dramatically improve display quality by a relatively simple method without characteristics.
A CD can be realized at low cost.

[0019]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram showing an AM according to an embodiment of the present invention.
FIG. 2 illustrates a cross-sectional structure of one pixel portion of the substrate, and FIG. 2 illustrates a cross-sectional structure of each process from formation of an insulating film to before formation of a pixel electrode in a process of manufacturing an AM substrate. In FIGS. 1 and 2, the same or corresponding parts as those in FIGS. 3 and 4 are denoted by the same reference numerals, and detailed description is omitted.

In FIG. 1, an AM substrate of the present invention is provided with an active element 2 and an address wiring 3 on an insulating substrate 1 made of glass or the like, and an insulating film 4 having an uneven shape so as to cover the active element 2 and the address wiring 3. And a pixel electrode 6 connected to the active element 2 through an opening 5 formed in the insulating film 4.

As shown in FIG. 2, in the process of forming an insulating film on an AM substrate according to the present invention, first, an insulating substrate 1 provided with an active element 2 and an address wiring 3 is provided.
Then, a positive photosensitive resin 4a diluted with a solvent is applied so as to cover the active element 2 and the address wiring 3 (application step). Next, the substrate coated with the photosensitive resin 4a is heated using a baking apparatus having a hot plate in which high-temperature portions and low-temperature portions having an area smaller than the size of the pixel electrode are alternately distributed, thereby removing the solvent 7 by heating. Evaporate (first baking step). In this step, since the hot plate has a high-temperature portion and a low-temperature portion, the solvent in the high-temperature portion of the photosensitive resin 4a starts to evaporate, the resin concentration gradually increases, and the film thickness shrinks. Go. With the shrinkage of the film in the high temperature part, the resin dissolved in the solvent gathers on the low temperature part side, and the film thickness gradually increases. When baking is performed for a certain period of time, the solvent of the resin film evaporates,
By the mechanism described above, a state is maintained in which the irregularities formed between the high-temperature portion and the low-temperature portion are maintained.

An acrylic resin is desirable as the photosensitive resin. The reason is that a thin film transistor using amorphous silicon is generally used as an active element. However, the heat-resistant temperature of this element is usually about 300 ° C., and the curing temperature of the resin must be lower than that. In the manufacturing process for converting an AM substrate into an LCD, a heat treatment of about 200 ° C. is usually performed, so that a higher performance is required as the heat-resistant temperature of the resin. This is because they can be obtained relatively inexpensively.

Next, ultraviolet rays 10 are irradiated using the mask 9 to expose the resin 4a at a predetermined position (exposure step).
A predetermined opening 5 is formed by processing with a developer or the like (development step). Lastly, a second baking step is performed using a normal baking apparatus, and the resin is cured to form the insulating film 4 having irregularities. When the pixel electrode 6 is formed on the insulating film 4 having irregularities, the surface of the pixel electrode has irregularities as shown in FIG.

As described above, according to the manufacturing method of the present embodiment, since fine irregularities can be formed on the insulating film below the pixel electrode, the pixel electrode surface becomes a diffusion surface, so that it is relatively simple. This method can dramatically improve the display quality without adding new expensive manufacturing equipment and without having a metallic glossy reflection characteristic. An active matrix substrate can be manufactured.

In the embodiments, the positive type photosensitive resin is described, but the present invention is not limited to this. As long as the resin has photosensitivity, the same effect can be obtained regardless of whether it is a positive type or a negative type.

Here, a hot plate used in the first baking step, in which high-temperature portions and low-temperature portions are alternately arranged, will be described. Although the surface of the hot plate is flat and the high and low temperature parts are formed, fine irregularities are provided on the surface of the plate, and when the substrate is placed on it, the difference in heat transfer to the substrate May occur.
In short, a device that effectively generates a high-temperature portion and a low-temperature portion on the substrate may be used.

[0028]

As described above, according to the present invention, fine irregularities can be formed on the insulating film below the pixel electrodes of the AM substrate by a relatively simple method and equipment. Since the pixel electrode surface formed above can be a diffusion surface, there is no increase in the number of new steps,
Metallic luster reflection on pixel electrodes, which is a problem with conventional reflective LCDs, is unnecessary because it does not require the addition of expensive manufacturing equipment and requires only a minimum amount of expensive materials. The characteristics can be eliminated, and the display quality can be dramatically improved.

[Brief description of the drawings]

FIG. 1 is a sectional structural view of an AM substrate according to an embodiment of the present invention.

FIG. 2 is a cross-sectional structure diagram showing a process of forming an insulating film on an AM substrate according to an embodiment of the present invention.

FIG. 3 is a sectional structural view of a conventional AM substrate.

FIG. 4 is a cross-sectional structure diagram showing a process of forming an insulating film on a conventional AM substrate.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 insulating substrate 2 active element 3 address wiring 4 insulating film 4 a photosensitive resin 5 opening 6 pixel electrode 7 solvent 8 hot plate 9 mask 10 ultraviolet ray

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H092 HA15 HA27 HA28 JA24 JB58 MA29 NA01 NA19 NA25 5C094 AA06 BA03 BA43 CA19 DA15 EA03 EA04 EA07 FA04 FB01 FB20 GB01

Claims (5)

[Claims] A step of forming an active element and an address wiring on an insulating substrate; a step of forming an insulating film so as to cover the active element and the address wiring; and a step of forming the active element through an opening formed in the insulating film. Forming a pixel electrode connected to an element in a matrix form, wherein the step of forming the insulating film includes a step of forming a photosensitive layer diluted with a solvent so as to cover the active element and the address wiring. Step of applying a photosensitive resin and heating the substrate on which the photosensitive resin is applied so that high-temperature portions and low-temperature portions having an area smaller than the size of the pixel electrode to be formed are alternately distributed to evaporate the solvent. A first baking step, an exposure / development step of selectively exposing and developing the photosensitive resin after evaporating the solvent to form an opening, and a photosensitive resin Method for manufacturing an active matrix substrate characterized in that comprising a second baking step of curing. 2. The method according to claim 1, wherein the photosensitive resin is made of an acrylic resin. 3. A first baking step of heating so that high-temperature portions and low-temperature portions are alternately distributed, wherein high-temperature portions and low-temperature portions having an area smaller than the size of a pixel electrode to be formed are alternately distributed. 2. The method for manufacturing an active matrix substrate according to claim 1, wherein a substrate coated with a photosensitive resin is placed on a hot plate and heated. 4. An active element and an address line are formed on an insulating substrate, an insulating film is formed so as to cover the active element and the address line, and connected to the active element through an opening formed in the insulating film. A heating device for evaporating a solvent of a photosensitive resin applied on the substrate in the insulating film forming step in a process of manufacturing an active matrix substrate in which pixel electrodes are formed in a matrix shape; It consists of a hot plate in which high-temperature parts and low-temperature parts with small areas are alternately distributed,
An apparatus for manufacturing an active matrix substrate, wherein a substrate coated with a photosensitive resin is placed on the hot plate and heated. 5. A hot plate in which a high-temperature portion and a low-temperature portion are alternately distributed so that fine irregularities are provided on the surface of the plate, and when the substrate is mounted thereon, a difference occurs in heat transfer to the substrate. 5. The apparatus for manufacturing an active matrix substrate according to claim 4, wherein: