JPS6186782A - Color liquid crystal display element - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a first substrate provided with a thin film transistor (TFT) array including a plurality of electrodes serving as display element units, and a first substrate provided with a counter electrode. The present invention relates to a display device that has a second substrate and performs display by electro-optical changes occurring between these substrates, and particularly relates to a color liquid crystal display element that provides a color filter and performs color display.

[Prior Art J] Conventionally, this type of device has used materials such as liquid crystal, EC (electrochromy), and EL (electroluminescence) as electro-optic modulation materials, and has been applied to a substrate using a thin film structure. A configuration is used in which a first substrate is provided with a driving semiconductor array, a second substrate is provided with a counter electrode, and a layer of electro-optic modulation material is sandwiched between these substrates. Hereinafter, as a representative example, a liquid crystal display device having a thin film semiconductor structure will be described with reference to the drawings.

3 and 4 are examples of substrates having thin film semiconductors,
An example in which this is configured as a liquid crystal display device is shown in FIG. 5. In other words, FIG. drive thin film transistor (FT: Th1
n Film Transistor). The TFT has a gate line 1a formed on the substrate 6.
(consisting of a transparent or metal thin conductive film), a gate electrode l provided on the gate line, an insulating film [91
3, a source line (made of a conductive film) 3a provided in contact with one end of the semiconductor, a drain electrode 4 provided at the other end of the semiconductor, and the like. The train electrode 4 constitutes an electrode serving as a display element unit. FIG. 4 is a plan view viewed from the direction of arrow B in FIG. 3, showing a part of the matrix drive circuit.

5 shows a liquid crystal display device composed of the substrate shown in FIG. 3 and a counter electrode substrate, and the line A shown in FIG.
- It is a sectional view corresponding to A'.

In FIG. 5, 6 and 8a are substrates such as glass, 4 is the aforementioned drain electrode, and 7 is a counter electrode.

4.7, rn203. A transparent conductive film such as 5n02 or a metal thin film such as Au, Al, Pd or the like is used depending on the case. 1 and 3a are a gate electrode and a source line, respectively, An, Au, Ag, Pt, P
Metals such as d and Cu are used. 5 is the insulating film 13
An example in which the film is formed only on the gate line such as a is specially shown, and 8 is an insulating film provided as necessary, and can also serve as an alignment film. 2 is CdS, CdSe, T
e.

Semiconductor such as amorphous silicon, 9 is a shacer, l
O is a liquid crystal layer. In addition, in display devices, various liquid crystal molecule orientation states are available depending on whether a display mode such as dynamic scattering mode (DSM) or twisted nematic (TN) is used, or whether the device is a transmissive type or a reflective type. Optical detection means such as a deflection plate, an input/quarter plate, and a reflection plate are appropriately set.

In such a device, a common method for performing color display is to form a color filter on either the substrate on which the driving semiconductor array is provided or the opposing counter electrode substrate.

[Problems to be Solved by the Invention] However, color filters made of dyes are prone to fading due to incident light, and are particularly prone to fading due to ultraviolet rays.
As shown in FIG. 2, the liquid crystal display element incorporating the color filter is equipped with another glass-like ultraviolet cut filter 12.
was incorporated. For this reason, the display element has had the disadvantage that it is necessarily thick due to its structure.

The present invention has been made in view of these conventional drawbacks, and an object of the present invention is to provide a color liquid crystal display element that is thin and has good light resistance as a display element incorporating a color filter.

[Means for solving the problem] In order to reduce the thickness of the element, it is necessary to incorporate an ultraviolet cut filter or a substance with an equivalent function into the element.

However, it is technically very difficult to incorporate the ultraviolet cut filter directly into the interior. Therefore, in the present invention, instead of incorporating an ultraviolet cut filter inside, a polyimide resin having the same function as the ultraviolet cut filter is formed inside the element. The polyimide resin used here is well known as an alignment material for liquid crystals, but is not well known as a material that blocks ultraviolet rays.

Specifically, as shown in FIG. 1, a transparent electrode (
A pixel electrode 14) is formed, a dye layer (color filter) 18 is formed thereon via an insulating film 13, and a polyimide resin layer 17 is further formed on the dye layer 18. The problem is that polyimide resin
For example, N-methylpyrrolidone is used as a solvent for the polyamic acid resin component, which is the precursor, and because this solvent dissolves the dye layer during coating, it cannot be directly formed on the dye layer. be. Therefore, in the present invention, by forming the transparent insulating layer 18 between the dye layer 1'8 and the polyimide resin layer 17, the dye layer is free from the solvent contained in the coating solution of polyamic acid, which is a precursor in the polyimide resin. This prevents the negative effects of Furthermore, by rubbing the surface of this polyimide resin, an alignment function is imparted to the liquid crystal molecules.

[Function] The polyimide resin used in the present invention (for example, the polyamide resin described in US Pat. No. 3,179,634 can be used) functions as an alignment material for liquid crystals, and the resin itself functions as an ultraviolet cut filter. also works. Therefore, by forming this polyimide resin on the dye layer inside the liquid crystal, it becomes unnecessary to provide an ultraviolet cut filter outside one display element.

[Example] An example of the present invention will be described with reference to FIGS. 6 to 8. FIG. 6 is a schematic cross-sectional view showing one embodiment of the process of forming a dye layer on a thin film transistor.

In FIG. 6(a), first, a pixel electrode 14 made of a 100 OA ITO film was formed into a desired pattern on a substrate (glass; 7059 manufactured by Corning Incorporated) 6 by a photorin process. In b), l is 10
Vacuum deposition was performed to a thickness of 0 OA, and a gate electrode 1 with a desired pattern was formed by a photorin process.

Next, in the same figure (C), an insulating film 13 made of photosensitive polyimide is applied to a thickness of 100 OA, and through exposure and development processing, a through hole is formed for the pixel electrode 14 to contact the drain electrode 4. In the same figure (d), SiH4 diluted with H2 is deposited by glow discharge method in vacuum.

After forming a 200 OA thick photoconductive layer 15 (intrinsic layer = i layer) made of an a-Si layer, an n'' layer 16 made of an a-Si layer is formed thereon by the same process,
Furthermore, the N3 layer 16 is etched into a desired shape by a dry etching method to form a thin film transistor. As shown in FIG. Electrode 3 and drain electrode 4 were formed. The pixel electrode (drain electrode 4) where the thin film transistor is formed in this way
A dye layer (color filter) was formed on top for one day as shown in FIG.

Here, the process of forming the dye layer (color filter) 18 on the substrate will be explained in more detail.

First, a positive resist (trade name, 0FPR80G, Tokyo Ohka type) was coated with 5000 to 700% by spinner coating method.
The 0th order coated on the pixel electrode with a film thickness of 00A at 80℃, 3
After performing pre-beta for 0 minutes, mask exposure was performed with ultraviolet light, immersion in a special developer for 1 minute, and immersion in a dedicated rinsing solution for 1 minute to form a resist mask.
Next, the entire surface of the photosensor array on which the resist mask was formed was exposed to light to make it soluble in a solvent. Next, the photosensor array and the copper phthalocyanine packed in the No port were installed in a vacuum container, and the vacuum level was 104~1G" To
In rr, the No port was heated to 450 to 550°C to deposit copper phthalocyanine to a film thickness of 400OA. Thereafter, a patterned blue dye layer was formed by immersing and stirring in a developer exclusively for 0FPR and removing unnecessary portions of the deposited film while dissolving the resist mask. Subsequently, 0FPR800 was applied in the same process on the photosensor array on which the patterned blue dye layer was formed.
After coating, exposing and developing, a resist mask corresponding to the next patterned green dye was formed. After the entire surface was exposed, it was installed in a vacuum evaporator, and this time 45% of PB phthalocyanine was applied.
A film of 30 GOA was obtained by vapor deposition at 0 to 550°C. Thereafter, it was immersed in a developer and stirred to form a patterned green dye layer. Furthermore, by using exactly the same process, Irgazine Red B was produced as a perylenetetracarboxylic acid derivative red pigment.
PT (Product name: Manufactured by Ciba Geigy (I No. 71127)
) was deposited by about 3,000 people at 400 to 500°C, and treated with a developer to obtain a patterned red dye layer.

After forming the dye layer in this way, as shown in FIG. 6(h), a negative resist (for example, Tokyo Ohka 0DUR) is formed as a transparent insulating layer 19 on the entire surface of the substrate, and further on the entire surface. Apply polyimide resin to a thickness of 1200A, and
Polyimide resin layer 1 was cured by heating at 50°C for 1 hour.
7 was formed (see FIG. 1), and after sintering, the surface of the polyimide resin layer 17 was subjected to a rubbing treatment to impart an alignment function for aligning the liquid crystal.

A color liquid crystal display element can be constructed by placing an electrode substrate made of a polyimide resin layer imparted with an alignment function in this way and the other counter electrode substrate facing each other, and injecting liquid crystal into the gap between them.

In addition, other methods of forming the dye layer include not only forming the dye layer on an electrode substrate on which a thin film transistor is formed as shown in FIG.
As shown in FIG. 8, a dye layer can be formed on the transparent electrode formed on the other electrode substrate, and a color liquid crystal display element can be constructed as shown in FIG. 7.

[Effects of the invention 1 The present invention has the following unique effects.

1. Since the polyimide resin layer formed inside the element blocks ultraviolet rays, there is no need to provide an external ultraviolet ray cut filter, and the entire display element can be made thinner.

2. Since the polyimide resin as the alignment material plays the role of an ultraviolet cut filter as described above, the light resistance of the color filter consisting of the dye layer is improved and the fading and deterioration of the display element is prevented.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of an element showing the basic concept of the present invention. FIG. 2 is a cross-sectional view of an example of a conventional color liquid crystal display device, FIG. 3 is a perspective view of a substrate having a thin film semiconductor, and FIG.
The figure is a plan view viewed from the direction of arrow B in FIG. 3, FIG. a) to (h) are schematic cross-sectional views showing one embodiment of the dye layer forming process according to the present invention, FIG. 7 is a perspective cross-sectional view of a color liquid crystal display element according to the present invention, and FIG. 8 is a schematic cross-sectional view showing another embodiment of the dye layer forming process according to the present invention FIG. 2 is a configuration cross-sectional view showing an example. 1: Gate electrode, 1a: Gate line, 2: Thin film semiconductor, 3: Source electrode. 3a = source line, 4 ni drain electrode. 6.8a: Substrate, 7: Counter electrode, lO: Liquid crystal layer, 12:
Ultraviolet cut filter, ゝ13: Insulating film. 14: Pixel electrode, 15: Photoconductive layer (a-9i(i)), Hl: n'' layer (
a-Si(n”)). 17: Polyimide resin layer, 18 Two-color layer (color filter), 18: Transparent insulating layer.

Claims (1)

[Claims] In a liquid crystal display element using a thin film transistor in which a liquid crystal is sandwiched between upper and lower electrode substrates, a color filter consisting of a dye layer is first formed on the transparent electrode of one of the electrode substrates, and then a color filter is formed on the transparent electrode of one of the electrode substrates. After forming a transparent insulating layer on a color filter and further forming a polyimide resin layer on the transparent insulating layer, the surface of the polyimide resin layer is given an alignment function for aligning liquid crystal molecules. A color liquid crystal display element using characteristic thin film transistors.