JPS6243098A - Formation of transparent electrode for electroluminescent display - 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] [Summary of the Invention] The present invention relates to an electroluminescent (hereinafter referred to as EL)
This relates to a method of forming transparent electrodes for displays.
In order to add a taper to the transparent electrode formed in a stripe shape, after forming the transparent electrode film, a film having a higher etching rate than the etchant of the transparent electrode is formed, a resist pattern is formed on the crotch, and a tapered shape is formed by ID etching. After forming the electrode, the film is immersed in a solution that melts the film, and the film containing the resist pattern is removed to form a tapered transparent electrode.

[Industrial application field]

The present invention relates to a method of forming a transparent electrode for an EL display, and in particular to a method for forming a transparent electrode for an EL display, in which a film formed on the transparent crotch of the electrode is removed to shorten the electrode forming process time in order to form a tapered transparent electrode. Regarding the forming method.

[Conventional technology]

Conventionally, EL displays not only can be made flat, but also consume less power, have no force or jitter, and are X-Y matrix, so they can reduce screen distortion.
Less than T (cathode ray tube). Its configuration is shown in FIG. That is, a striped transparent ViA 2 is formed on the glass substrate 1. This transparent electrode 2 is tapered to increase the dielectric strength of the insulating layer 3.
The surface must be finished smooth. On the insulating layer 3, a light-emitting layer 4 is formed using zinc sulfide (ZnS) as a base material and adding manganese (Mn) or the like which acts as a light-emitting source.

Further, an insulating layer 5 is formed on the light emitting layer, and a back electrode 6 of a gold layer is formed in a matrix shape on the insulating layer 5, perpendicular to the striped transparent electrode 1, and the back electrode 6 and the transparent electrode 6 are formed in a matrix shape. It is made to emit yellow-orange light by applying an alternating voltage or the like between the two electrodes, and it is known that various colors can be obtained by using rare earth fluoride as a light source. .

The steps for obtaining tapered transparent electrodes on the glass substrate 1 in an EL display having such a configuration will be explained with reference to FIG.
First, tin oxide (
A first transparent thin film layer 2a of SnO3) or titanium oxide (Ti02) is sputtered and heat treated at around 500°C.Next, a second transparent thin film is formed on the heat treated first transparent thin film layer 2a. After sputtering 1'i2b using low-temperature reactive DC sputtering, a striped resist pattern 7 is formed using photolithography, and etching 8 is performed using hot concentrated hydrochloric acid to form the first and second transparent thin film layers as shown by the arrows. 2
a.

2b is subjected to particle etching in the thickness direction and particle etching in the surface direction. On this occasion.

The first transparent thin film layer 2a is completely polycrystalized by heat treatment, whereas the second transparent thin film layer 2b is in an amorphous state, so the etching rate is different (see FIG. 2 fb).
As shown in the figure, more side etching was also done directly below the resist pattern.

A tapered transparent electrode 2 is formed. Next, the resist pattern 7 is removed. When forming the insulating layer on the second transparent thin film layer 2b, a temperature of around 300°C is applied, so the second transparent thin film layer 2b in an amorphous state causes a thermal reaction that affects the insulating layer and is not suitable for the purpose. Because it is difficult to obtain a film that matches the resist pattern, the second transparent thin film layer 2b is further heat-treated after the resist pattern is removed, as shown in FIG. 2 (tc).

[Problem that the invention seeks to solve]

According to the above-mentioned conventional structure, not only does it take a long time to heat-treat the second transparent "i-film layer 2b, usually about 1 to 2 hours, but also the time required to heat-treat the second transparent "i-film layer 2b" increases.

In order to obtain a tapered transparent electrode from 2b, mutually dependent factors such as etching conditions, film resistance, and film thickness must be considered.

[Means for solving problems]

The present invention has been made in view of the above-mentioned drawbacks, and its purpose is to provide a method for forming a transparent electrode that does not require a long heat treatment process by omitting the heat treatment process of the second transparent thin film layer. a step of forming a transparent thin film layer on the substrate and subjecting it to heat treatment; a step of forming a second layer film having a higher etching rate than the etchant of the transparent thin film layer on the transparent thin film layer; A step of forming a striped resist pattern on the crotch and side etching to form a tapered electrode formed of the transparent thin film layer and a second layer film, and easily melting the second layer film. This is achieved by a method for forming a transparent electrode for an electroluminescent display, which comprises the steps of immersing the transparent thin film layer in a non-corrosive liquid and removing the second layer film.

[For production]

In the present invention, an amorphous thin film layer that is not heat-treated is sputtered on a heat-treated transparent thin film layer when tapering the transparent electrode of an EL element, but this thin DJ layer does not need to be transparent; For the niche layer of the electrode formed by the transparent thin film layer, a thin film layer with a larger etching rate is selected, and by dissolving the thin film layer with a removal solution that does not corrode the surface of the electrode, a thin film can be formed even after the resist pattern is removed. The layer is removed.

(Embodiment) Two embodiments of the present invention will be described below in detail with reference to FIGS. 1(a) to (C). In FIG. (ITO)
In the sixth step, the transparent thin film rw2a is heat-treated at about 500° C. to polycrystallize the transparent thin film layer 2a. °C), the 21st pattern 11W2b' having a higher etching rate is sputtered, and in the next step, a resist pattern 7 is formed on the second and rii pattern 2b' by photolithography.
By etching with hot hydrochloric acid, which is an etchant, the hot concentrated PA acid penetrates from the part where the resist 1 pattern is not formed, as shown by the arrow, in the thickness direction of the second layer 1'' film 2b', which is an aluminum film. Also, side-etch the surface direction. As a result, θ-10 as shown in Fig. 1 fb)
Electrodes 2a, 2b' with a taper of about 15 degrees
Then, as shown in FIG. 1(C), after peeling off the resist pattern 7, the aluminum film on the second side 2b' is removed using phosphoric acid that does not attack the transparent thin film layer 2a. When only the transparent thin film layer 2a is left, a tapered transparent electrode 2 of a predetermined height is formed.

In the above embodiment, phosphoric acid was used as an etchant to dissolve only the second ridge 2b' without damaging the aluminum film and the transparent thin film layer, but the invention is not limited to this, and for example, The second layer may be a transparent film, and a second layer film and an etchant that satisfy the first-order conditions may be selected.

(1) For the etchant of the transparent thin film layer 2a that will become the transparent electrode, select a material that will form the second layer film and have a higher etching rate.

(2) Select an etchant that completely melts only the second layer without corroding the surface of the transparent electrode.

Obviously, any such film and etchant may be used.

〔Effect of the invention〕

Since the present invention is constructed as described above and the process is selected, the heat treatment step after patterning can be omitted compared to the case where conventional non-annealed ITO is re-annealed as a 2W 1st film. In the present invention, an esoching process is added instead of this heat treatment process, whereas in the conventional heat treatment process, the heat treatment is performed in a vacuum for 1 to 2 hours.

In the ethoching process of the present invention, the process time can be significantly shortened by simply immersing it in the Encinda solution in a normal atmosphere, and it takes about 10 minutes. Furthermore, since the transparent electrode is not a two-layer film, the design is simple and the transparent electrode can be formed without affecting the insulating film formed on the transparent electrode.

[Brief explanation of drawings]

Figures 1 to (C) are side sectional views of an EL element showing the process of forming a transparent electrode for an EL display according to the present invention, and Figure 2 is a side sectional view of an EL element showing a process of forming a transparent electrode for an EL display according to the conventional Side sectional view 2 and FIG. 3 are perspective views showing a conventional EL display configuration. 1...Glass substrate. 2...Transparent electrode. 2a...first transparent thin film layer. 2b...Second transparent thin film layer. 2b'...2nd ra eye membrane. 3.5...Insulating layer. 4... Luminescent layer. 6... Back electrode. 7...Resist pattern. 8...Etching. Dōtsusu Jin 1 Moxibustion n゛ras Osaka 77-5Z' Fig. 1

Claims (3)

[Claims] (1) A step of forming a transparent thin film layer on a glass substrate and heat-treating it; a step of forming a second layer film having a higher etching rate than the transparent thin film layer on the transparent thin film layer; and a step of forming a second layer film on the transparent thin film layer. A striped resist pattern is formed on the eye membrane and the transparent thin film layer and the second layer are separated by side etching.
A step of configuring a tapered electrode formed of a layer film, and a step of removing the second layer film by immersing it in a liquid that easily dissolves the second layer film but does not corrode the transparent thin film layer. A method for forming a transparent electrode for an electroluminescent display, characterized in that: (2) The method for forming a transparent electrode for an electroluminescent display according to claim 1, wherein an aluminum film is selected as the second layer film. (3) The method for forming a transparent electrode for an electroluminescent display according to claim 1, wherein a phosphoric acid solution is selected as the liquid.