JPS6325356B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid crystal display element.
More specifically, in a so-called multilayer liquid crystal display element, in which three or more glass substrates are laminated and each has a liquid crystal layer between them, an intermediate glass substrate is sandwiched between upper and lower liquid crystal layers. This invention relates to the structure of a transparent conductive coating provided on the lower surface, that is, a transparent electrode pattern.

Conventionally, a liquid crystal display element is constructed by adhering two glass substrates 1 and 2 as shown in FIG. 1, and sealing a liquid crystal 3 between the two substrates. It had an electrode pattern 4 formed of a metal oxide transparent conductive film on its surface.
In fields such as wristwatches where such liquid crystal display elements are used, it is required to display various forms within a limited display area, and the electrode shapes are extremely complex, making it difficult to display with a single display element. The amount of information that can be collected is reaching its limits. Therefore, recently, a multilayer liquid crystal display element, in which a plurality of display elements are stacked and integrated, and has a plurality of liquid crystal layers and corresponding electrodes, has begun to be put into practical use. When manufacturing such a multilayer liquid crystal display element, there is a method of fixing and integrating a plurality of completed display elements 21 and 22 with an adhesive 23, etc., as shown in FIG. 2, but in this case, the display element The overall thickness of the adhesive increases, and air bubbles tend to get mixed in when bonding, which impairs the appearance. Therefore, when obtaining a display element composed of two layers, for example, a two-layer display element having two liquid crystal layers 34 and 35 is manufactured using three glass substrates 31, 32 and 33 as shown in FIG. It is possible that In this case, electrode patterns 3 are provided on both upper and lower surfaces of the central glass substrate 32.
6, 37 is required.

Usually, when forming an electrode pattern of a transparent conductive film, a photoetching method is used to obtain a complicated electrode pattern shape. This method is generally performed in the following steps. That is, first, a transparent conductive film of a metal oxide is uniformly formed on almost the entire surface of a glass substrate by a method such as vapor deposition, a photoresist film is formed on this film using a spinner, etc., and then a photoresist film is formed on this film. A photomask is placed on the photomask, exposed by irradiating it with ultraviolet rays, etc., and then developed by immersing it in a developer, baking it at a temperature of around 100°C, and then immersing it in an etching solution. Remove unnecessary photoresist. Thereafter, the exposed portions of the transparent conductive film that are not protected by the photoresist are etched away, and finally the photoresist film is peeled off to complete the formation of the electrode pattern.

Now, the central glass substrate 32 of the two-layer display element
When forming electrodes on both the upper and lower surfaces of the substrate, it is necessary to roughly repeat the steps of the photo method described above. That is, a transparent conductive film is similarly uniformly formed on the entire lower surface of the glass substrate 32 on which the electrode pattern 36 is formed on the upper surface as described above, and the steps of photoresist film formation, exposure, development, and baking are carried out. conduct,
Here, in order to protect the electrode pattern 36 on the upper surface, an etching resist film is formed on the surface of the electrode pattern 36, and then, through a process of etching and resist film peeling, electrode patterns 36 and 37 are formed on both the upper and lower surfaces. be done.

In order to form electrode patterns on both the upper and lower surfaces of a single glass substrate in this manner, an etching-resistant protective film is required to protect the previously formed electrode pattern 36 on the upper surface during the etching process. Forming such a protective film not only unnecessarily increases the manufacturing process, but also damages the electrode pattern on the top surface and the photoresist film on the bottom surface, increases etching defects, and increases manufacturing costs. It also causes a waste of resources.

Therefore, in the present invention, when forming transparent electrode patterns on both sides of a single transparent substrate,
A metal oxide transparent conductive film with different etching characteristics is formed on one side and the other side, and then only the metal oxide transparent conductive film formed on one side is etched. By using two types of etching liquids each having a high etching rate, it is possible to omit the formation of a protective film as described above and to form transparent electrode patterns on both sides of a single substrate.

Examples of the present invention will be described below.

(Example) One surface of a single glass substrate was coated with stannic oxide (SnO ₂ ) as a first metal oxide transparent conductive coating.
A film is formed by sputtering, CVD, spraying, etc., and an electrode pattern is formed by the photoresist method described above through the steps of photoresist coating, exposure, development, baking, etching, and resist film peeling. On the surface, an indium oxide (In ₂ O ₃ ) film is formed as a second metal oxide transparent conductive film by vapor deposition or the like, and photoresist coating, exposure, development, baking, etching, and resist film peeling are similarly performed. Through a process, electrode patterns of transparent conductive films are formed on both the top and bottom surfaces of a single glass substrate. Here, in order to create a difference in the etching rate between tin oxide and indium oxide, ordinary tin oxide film etching is performed using zinc powder and dilute hydrochloric acid as the first etching solution for tin oxide. Although any method may be used, a hydrochloric acid bath that does not use zinc powder is used as the second etching solution for indium oxide. Stannic oxide is a chemically more stable film than indium oxide; the former is difficult to etch in a hydrochloric acid bath, but the latter is relatively easy to etch.

In the above example, on the premise of chemical etching of a transparent conductive film, electrode formation using a stannic oxide film was performed.
This was carried out before the indium oxide film, but when etching is performed using plasma etching or ion etching, the etching rate of the stannic oxide film is faster than that of the indium oxide film, so it is not suitable for the above example. Conversely, it is also conceivable to form the indium oxide electrode before forming the stannic oxide film.

As shown in the above embodiments, according to the present invention, an etching resist film is formed on one side of a transparent conductive film on which electrodes have been formed in advance to protect the electrode when etching the other side. The final step of removing the protective film can be omitted. This not only reduces manufacturing man-hours and materials by simply omitting two steps, but also has the effect of greatly reducing process defects caused by pinholes, scratches, etc. in the etching resist film required in the conventional process. According to the present invention, it is possible to reduce the manufacturing cost of liquid crystal display elements and provide inexpensive digital watches to society at large.

Note that after forming a common side electrode pattern for the liquid crystal layer 24 on the upper surface side of the intermediate glass substrate 32, a transparent insulating film such as SiO ₂ is formed on the electrode pattern, and then a liquid crystal layer 35 is formed on the lower surface side. It is clear that the present invention can also be applied to the case of forming segment electrode patterns for. In that case, the transparent insulating film such as SiO ₂ plays the role of protecting the electrode pattern on the upper surface side and also serves as a film to prevent alkali ion elution from the glass substrate. The effect will also be more complete.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a conventional liquid crystal display element. FIG. 2 is a cross-sectional view of two liquid crystal display elements bonded and integrated. FIG. 3 shows a cross-sectional view of a two-layer liquid crystal display element composed of three glass substrates. 31, 32, 33...Glass substrate, 34, 35
...Liquid crystal layer, 36, 37... Electrode pattern.

Claims (1)

[Scope of Claims] 1. A method for manufacturing a multilayer liquid crystal display element in which a liquid crystal layer is provided between three or more transparent substrates arranged in a stacked manner, including: (b) forming first and second metal oxide transparent conductive films having different etching characteristics on both sides of a transparent substrate disposed on the substrate; (c) etching the second coating with a second etching solution having a higher etching rate than the first coating; the first and second surfaces formed on both sides of the transparent substrate;
A method for manufacturing a liquid crystal display element, comprising forming transparent electrode patterns on each film using etching solutions having different etching rates. 2. The first metal oxide transparent conductive coating is made of stannic oxide, the second metal oxide transparent conductive coating is made of indium oxide, and the first etching solution uses zinc powder and dilute hydrochloric acid; 2. The method of manufacturing a liquid crystal display element according to claim 1, wherein the second etching solution is hydrochloric acid.