JPH0383022A - Production of electrooptical device - Google Patents

Abstract

PURPOSE:To improve the through-put of the production process of the device by executing the process with two times of photoetching stages for producing active element substrates. CONSTITUTION:A conductor layer which the constitutes picture element electrodes and auxiliary constituting elements for 1st conductor wirings is formed on a substrate. A 1st conductor layer which constitutes the main constituting elements for the 1st conductor wirings is formed on the conductor layer. The production process is constituted with the following stages. The photoetching to simultaneously form the patterns of the 1st conductor wirings and the picture element electrodes is executed by 1st time of exposing to selectively form nonlinear electrical conduction layer on the 1st conductor wirings. The etching to remove the unnecessary 1st conductor layers remaining on the picture element electrodes is executed with the selectively formed nonlinear electrical conduction layers as a resist form the 2nd conductor layer for the 2nd conductor wirings and the 2nd conductor wirings is pattern-formed. The stages appear to be increased, but the process is executed with two times of the photoetchings. The yield is thus improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing an electro-optical device. More specifically, a nonlinear element having a conductor-nonlinear electrically conductive layer-conductor structure (conventionally, it is called an MIM element because it is composed of a metal-insulator-metal structure, and hereinafter also referred to as MIM element) The present invention relates to a method of manufacturing an electro-optical device in which multiplex characteristics are improved by providing an IM element (referred to as an IM element) for each pixel electrode on an active substrate.

[Prior Art] In recent years, simple matrix electro-optical devices mainly using liquid crystals have been put into practical use, and have come to be widely used as flat panel displays for personal computers, personal word processors, and the like. Therefore, there are growing expectations for electro-optical devices that can meet the demands for larger display information capacity, higher density, and higher speed, and that the manufacturing process is relatively simple, such as the two-terminal e-element type, especially the active matrix using HIM elements. There is. This MIM element uses tantalum oxide as a nonlinear electrically conductive layer, and our company has already put it into practical use in liquid crystal television receivers and other devices.

Furthermore, the inventors have already proposed an active matrix electro-optical device using an MIM element with improved electrical characteristics using a nonlinear electrically conductive layer made of an organic thin film. According to this, it is possible to assemble a process that requires only two photomasks/two photo-etching steps to fabricate an active element substrate, thereby simplifying the manufacturing process.

The already proposed manufacturing process using the two photomasks is as follows:
At least a step of forming a conductor layer 202 on the substrate 201, which serves as a pixel electrode and an auxiliary component of the first conductor wiring; b. forming a first conductor layer on the conductor layer; Step of forming the first conductor H2O3, which is the main component of the wiring, →
Fig. 2(a)c, the first conductor wiring 204 is simultaneously exposed in one exposure.
and a photoetching process to form a pixel electrode pattern, → FIG.
5, → FIG. 2(d), FIG. 2(e) e, Step of forming a second conductor layer 206 for the second conductor wiring, → FIG. 2(f) f, At the same time as patterning the second conductor wiring 207, unnecessary first conductor M remaining on the pixel electrode 20 days is formed.
A photoetching process for removing 2O9 (at this point, the first conductor wiring under the second conductor wiring remains) consists of six steps shown in FIG. 2(g) and FIG. 2(h).

[Problem M to be Solved by the Invention] What is particularly problematic here is the removal of the unnecessary first conductor layer on the pixel electrode in step f.

It is preferable that the first conductor wiring has as low a resistance as possible in order to reduce crosstalk and improve the aperture ratio.
For this reason, it is common practice to raise the substrate temperature to as high a temperature as possible to form a dense and thick film. In addition, in the process of forming a nonlinear electrically conductive layer, if the first conductor is not dense, the electrode may melt, and the formed nonlinear electrically conductive layer may become uneven in places due to resistance, so this can be prevented. In order to achieve this, the first conductive layer is required to be dense and have low resistance.

However, the second conductor layer has a short wiring length and does not need to have very low resistance. Therefore, in order to avoid damaging the nonlinear electrically conductive layer made of organic thin film, it is formed as thinly as possible at a low temperature with low damage. is common.

In this way, conductor layers in different states are etched simultaneously,
Moreover, since etching of the first conductive layer is started after etching of the second conductive layer is completed, side etching, overetching, This has caused variations in device characteristics and defects due to partial penetration of the etching solution into device portions, making the manufacturing of active device substrates unstable and reducing yield.

Therefore, the present invention reduces the manufacturing process and manufacturing equipment, minimizes the increase in manufacturing costs, and provides stable quality compared to not only those using TPT but also active matrix electro-optical devices using conventional HIM elements. It is an object of the present invention to realize a method for manufacturing an electro-optical device, which allows an active element substrate to be obtained and thereby constitutes an excellent electro-optical device.

[Means for Solving the Problems] A liquid crystal is sandwiched between a pair of active element substrates and a counter substrate, and on the active element substrate there is at least a first conductive wiring formed on the first conductive wiring. a nonlinear electrically conductive layer made of an organic thin film, a pixel electrode corresponding to a plurality of pixels, and a second electrically conductive layer that electrically connects the first conductive wiring and the pixel electrode via the nonlinear electrically conductive layer. A method for manufacturing an electro-optical device in which a body wiring is formed, at least the following steps: b. Forming a first conductor layer, which is a main component of the first conductor wiring, on the conductor layer; c. Forming the first conductor wiring and the pixel electrode in one exposure. a photoetching step of simultaneously forming a pattern; d) a step of selectively forming a nonlinear electrically conductive layer on the first conductor wiring; e1: using the selectively formed nonlinear electrically conductive layer as a resist; an etching step for removing unnecessary first conductor layer remaining on the pixel electrode, f. forming a second conductor layer for the second conductor wiring, g. forming the second conductor wiring; It is characterized by comprising a photo-etching process to form a pattern.

The method according to the present invention requires at least 7 steps, and the conventional method requires at least 6 steps. At the time of cleaning accompanying the formation of the nonlinear electrically conductive layer in step d, step e can be handled by simply adding one etching tank, so the increase in manufacturing steps is small and the load is small.

[Example 1] As the substrate 101, #7059 glass manufactured by Corning Co., Ltd. was used, and the conductor 10 for a pixel electrode with a thickness of 10 to 200 nm was used.
An ITO thin film (2) and a chromium thin film (1100 nm to 1 μm thick as the first conductor 103) are formed by sputtering to form a To/chromium laminated film.

→Figure 1(a) Next, using one photomask, pattern both the terminal part for electrical connection with the outside of the panel, the 400 first conductor wirings, and the pixel electrode of 400 x 640 dots. A pattern is formed by photoetching.

→Figure 1(b), Figure 1(C) Next, this substrate was coated with aniline (0.2M) to which pyridine (0.1M) was added using sodium perchlorate (0.5M) as a supporting electrolyte. 1. The acetonitrile solution was immersed in the electrolyte and the saturated calomel electrode immersed in the electrolyte.
Electrolytic oxidation polymerization is performed by applying a potential of 1 V for 10 minutes to form a polyaniline polymer film with a thickness of about 50 nm on the first conductor wiring, thereby forming the nonlinear electrically conductive layer 104.

→Fig. 1(d), Fig. 1(e) After this, the electrolytic solution is washed off by washing the substrate, and then the pixel electrode 105 not covered with polyaniline is removed.
Etching is performed to remove unnecessary chromium from the parts above.

→Fig. 1(f), Fig. 1(g) This etching process may cause incomplete formation of the nonlinear electrically conductive layer, or may cause the nonlinear electrically conductive layer to form before the second conductor wiring is formed. In case of slight damage,
Since the first conductor wiring in that area was also partially etched, the element that was supposed to be a short-circuit type defect was repaired, resulting in a very low defect count.

Furthermore, as the second conductor 106, a thickness of 5 Onm to
A chromium thin film of 1 μm is formed.

→Figure 1 (h) After this, the second conductor wiring 107 is patterned by photoetching so as to directly connect the first conductor wiring and the pixel electrode via the nonlinear electrically conductive layer. do.

→Fig. 1(i), Fig. 1(j) The active element substrate is thus completed. This active element substrate and a counter substrate provided with 640 orthogonal striped counter electrodes are combined to form a TN liquid crystal panel in which the alignment direction of the upper and lower substrates is twisted approximately 90 degrees with a 6 μm interlayer.

This liquid crystal panel has a bias ratio of 1/7 and a duty ratio of 1/7.
When driven at a speed of 400, a good contrast ratio of 1:30 or more and a wide viewing angle similar to that achieved with static driving were obtained.

Example 2 A TN mode electro-optical device was constructed by combining an active element substrate obtained using the same configuration and manufacturing method as Example 1 and a counter substrate on which color filters of three colors of red, green, and blue were formed. It was made into a color liquid crystal panel. In this liquid crystal panel, a contrast ratio of 1:20 or more was obtained for each color of red, green, and blue.

Example 3 Using a substrate with the same electrode configuration as the liquid crystal panel of Example Pig 1, sodium hydroxide (0.1M) was used as a supporting electrolyte, 2,
A methanol solution containing 6-xylenol (0.2M) as a raw material monomer was used as an electrolyte, and a potential of 0.5V was applied to a saturated calomel electrode immersed in the electrolyte to form a layer of about 40 nm on the first conductor wiring. An active element substrate similar to that of Example 1 was prepared by forming a poly(phenylene oxide) polymer film having a thickness of 100 mL to serve as a nonlinear electrically conductive layer. Further, C5-1018, a ferroelectric liquid crystal composition manufactured by Chisso Corporation, was used as the liquid crystal composition, and the same counter substrate as in Example 1 was used to prepare a ferroelectric liquid crystal panel with a substrate spacing of 2 μm. This liquid crystal panel can utilize the high-speed response characteristic of ferroelectric liquid crystals, and because the liquid crystal responds within several m5ec after the selection pulse is applied, the display can be rewritten within each frame even when driven at a frame period of about 100Hz. As a result, an extremely high-speed liquid crystal electro-optical device was obtained.

It was also confirmed that this active element substrate could operate in the same manner as in Example 1 when combined with a nematic liquid crystal.

Although the embodiments have been described above, the present invention is not limited to the above embodiments.

For example, in the above embodiment, the conductor was a metal electrode and chromium was used as the material, but other materials such as iron, copper, aluminum, tantalum, tungsten, molybdenum, nickel,
Metals such as titanium, gold, and platinum can be used alone or as alloys with these metals or with other metals. Furthermore, other than gold scraps, compounds with high electrical conductivity (for example, ITO and organic conductors) can also be used. However, it is preferable to use the same or similar layers as the first conductor layer and the second conductor layer from the viewpoint of symmetry of electrical properties and repairability by etching. It was also confirmed that various operations such as vapor deposition, electron beam irradiation vapor deposition, and baking after spin code are used alone or in combination to be effective.

Furthermore, electrolytic polymerization methods in which organic monomers are electrochemically electrolytically oxidized or electrolytically reduced on the surface of an electrode to cause a polymerization reaction to form a thin polymer film are well known, such as those published in Kagaku Kogyo Magazine 44. Vol. 6, No. 6, pages 462-472, and can be carried out using various methods. In addition, various monomers other than those mentioned above can be considered, such as aromatic compounds having an amine group other than aniline, aromatic compounds having a hydroxyl group such as phenol other than 2,6-xylenol, virol, thiophene, It is possible to use heterocyclic compounds such as furan, aromatic polynuclear hydrocarbons condensed with benzene, azulene, pyrene, etc., vinyl compounds such as vinylpyridine, acetylene and its derivatives, and the like. It is clear that all of these are applicable to the present invention.

In addition, it can be easily assumed that the present invention can be applied to any method that can selectively form a nonlinear electrically conductive layer on the first conductor wiring, such as selecting charged molecules onto an electrode by electrophoresis. It was confirmed that the method using adsorption (so-called electrodeposition method) can also be applied.

[Effects of the Invention] As explained above, according to the present invention, the manufacturing process of an active element substrate, which conventionally required three photoetching steps, can be reduced to two photoetching steps, thereby improving the manufacturing process of electro-optical devices. Improves throughput. In addition, at this time, the pixel electrode and the first conductor wiring are formed at the same time, and there is no need for precise alignment to prevent short circuit between the pixel electrode and the first conductor wiring during exposure, so the photoetching accuracy is close to the limit. The pixel electrode can be made larger, which is also effective in improving the aperture ratio.

Further, unlike a conventional HIM element using a tantalum oxide insulating film, in which a tantalum oxide insulating film is formed by oxidizing tantalum, which is the first conductor, according to the present invention, the first conductor is Since the insulating film is formed by depositing a film on the wiring, the film thickness of the first conductor wiring is not reduced. Therefore, when forming the metal thin film, the thickness of the conductor thin film is taken into consideration beforehand. This improves the throughput of metal thin film formation. This also improves the throughput of the manufacturing process and is very advantageous in terms of manufacturing costs.

Furthermore, the precise process control (forming conditions for the first conductive layer, forming conditions for the second conductive layer, forming conditions for the nonlinear electrically conductive layer, photoetching conditions for conductor wiring, etc.), the manufacturing method of the present invention has a very large margin for each, making it possible to create active element substrates with a stable and high yield, and manufacturing This is a very useful method.

Moreover, if the film formation is incomplete or if the second electrode is damaged in some way before it is formed,
In the conventional manufacturing method, the M element has a short-circuit type defect, but according to the manufacturing method of the present invention, the damaged part is removed at the same time as removing the unnecessary first conductor layer on the pixel electrode. Since the first conductive layer is also etched and the device is repaired, the present invention is further useful as a manufacturing method because the number of defects is extremely low.

[Brief explanation of drawings]

FIG. 1 is a diagram illustrating the manufacturing process of an active element substrate according to the present research. FIG. 1(a) is a cross-sectional view showing formation of a pixel conductor film and a first conductor film. FIG. 1(b) is a top view showing a pattern of a pixel electrode and a first conductor wiring formed by photoetching. FIG. 1(c) is a sectional view taken along line A-B in FIG. 1(b). FIG. 1(d) is a top view showing the formation of a nonlinear electrically conductive layer. FIG. 1(e) is a sectional view taken along the CD line in FIG. 1(d). FIG. 1(f) is a top view showing the first conductor on the pixel electrode having been removed in the step of removing the unnecessary first conductor on the pixel electrode. FIG. 1(g) is a sectional view taken along line E-F in FIG. 1(f). FIG. 1(h) is a cross-sectional view showing the formation of the second conductor thin film. FIG. 1(i) is a top view of the active element substrate completed by patterning the second conductor wiring formed by photoetching, and FIG. 1(j) is the 11ff
a (i) (This is a cross-sectional view taken along the line DG-H. 101...Substrate 102...Pixel electrode conductor 103...First conductor 104... ...Nonlinear electrically conductive layer 105...Pixel electrode 106...Second conductor 107...Second conductor wiring FIG. 2A is a diagram illustrating the proposed manufacturing process of an active element substrate using two photomasks and two photoetching steps. FIG. Figure 2(b) is a top view showing the pattern of the pixel electrode and the first conductor wiring formed by photoetching. Figure 2(C) is the line A-B in Figure 2(b). 2!!I (d) is a top view showing the formation of a nonlinear electrically conductive layer. FIG. 2(e) is a sectional view taken along line CD in FIG. 2(c). Figure (f) is a cross-sectional view showing the formation of the second conductor thin film. Figure 2 (g) is the upper surface of the active cable substrate completed by patterning the second conductor wiring formed by photoetching. Figure 2 (h) is a cross-sectional view taken along the line E-F in Figure 2 (g). 201...Substrate 202...Pixel electrode conductor 203... ...First conductor 204...First conductor wiring 205...Nonlinear electrically conductive layer 206...Second conductor 207... Second conductor wiring 208... Pixel electrode 209... More than what remains of the first conductor

Claims (1)

[Scope of Claims] A liquid crystal is sandwiched between a pair of active element substrates and a counter substrate, and on the active element substrate there is at least a first conductive wiring and an organic layer formed on the first conductive wiring. A nonlinear electrically conductive layer made of a thin film, a pixel electrode corresponding to a plurality of pixels, and a second electrically conductive wire that electrically connects the first electrically conductive wire and the pixel electrode via the nonlinear electrically conductive layer. A method for manufacturing an electro-optical device, comprising: a. forming a conductive layer on the substrate, which becomes a component of a pixel electrode and auxiliary first conductive wiring; b. Step of forming a first conductor layer, which is a main component of the first conductor wiring, on the conductor layer; c. Simultaneously patterning the first conductor wiring and the pixel electrode in one exposure; d. selectively forming a nonlinear electrically conductive layer on the first conductor wiring; e. using the selectively formed nonlinear electrically conductive layer as a resist to form the pixel. Etching step to remove unnecessary first conductor layer remaining on the electrode, f. Step of forming a second conductor layer for the second conductor wiring, g. Pattern formation of the second conductor wiring. 1. A method of manufacturing an electro-optical device, comprising a photo-etching process.