JPH01184830A - Dry etching process - Google Patents

Abstract

PURPOSE:To accelerate the etching rate of a ZnS film while augmenting the selection ratio of resist by adopting a compound containing methyl radical as an etching gas in the dry etching process of the ZnS film. CONSTITUTION:A ZnS film is processed by ion or radical generated by discharging a gas of a compound containing a methyl radical. The compound containing the methyl radical is CH3OH. Thus, the reaction product is Zn(CH3)2 having a boiling point of 46 deg.C, since the steam pressure is high, the etching rate of ZnS film is accelerated. Through these procedures, the etching rate of the ZnS film can be accelerated to augment the selection ratio of resist.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a dry etching method for forming a pattern on a ZnS film used as a light emitter in an electroluminescent display or the like.

BACKGROUND OF THE INVENTION In recent years, dry etching methods have been widely used in the manufacturing process of semiconductor devices, but not in the manufacturing process of electroluminescent devices.

Conventionally, in the electroluminescence manufacturing process, pattern formation of a ZnS film has been carried out by wet chemical etching mainly using a mixed solution of nitric acid, phosphoric acid, and acetic acid. However, since etching proceeds isotropically in wet chemical etching, the etching of the ZnS film proceeds to the bottom of the mask, making it difficult to form a pattern with high precision. Therefore,
Dry etching methods are being studied.

An example of the above-mentioned conventional dry etching method will be described below with reference to the drawings.

FIG. 2 shows a schematic diagram of a dry etching apparatus for carrying out a conventional dry etching method. In FIG. 2, 1 is a vacuum vessel, 2 is an insulator, 3 is an electrode for placing an object to be etched, 4 is an object to be etched, and 6 is a high frequency power source as means for causing glow discharge. 6 is a gas supply hole connected to a means (not shown) for introducing etching gas;
7 is an exhaust hole connected to an exhaust means (not shown), and 8 is a plate-shaped electrode connected to ground.

The operation of the dry etching apparatus constructed as described above will be explained below. First, after evacuating the inside of the vacuum container 1 to 1 mTorr or less by an exhaust means,
A constant pressure is maintained while introducing an etching gas at a constant flow rate according to the object to be etched from the gas supply means. Thereafter, power is supplied from the high frequency power source 6 to cause glow discharge and generate plasma. The object to be etched is removed by ions and radicals in the plasma. The object to be etched is Z
In the case of an nS film, the etching gas contains halogen, but as mentioned above, when the etching gas contains a halogen, the reaction product of the ZnS film is ZnF2 (
ZnC12 (boiling point = 1600°C) and ZnC12 (boiling point = 730°C), and because the boiling point is very high, the etching rate is very slow. Furthermore, since the etching speed of the resist film generally used as a mask material is fast, there is a problem in that the resist film used as a mask must be thick.

In view of the above-mentioned problems, the present invention aims to increase the etching rate of the ZnS film and improve the selectivity to resist. A compound containing a methyl group is used as the methyl group. The dry etching method according to the second aspect of the present invention uses a mixed gas of a compound containing a methyl group and an inert gas as an etching gas for the ZnS film.

Effect The effect of the first invention of the present invention is that by using a compound containing a methyl group as an etching gas, the reaction product is
The boiling point of the reaction product of n (CH3) 2 is 46°C, and the high vapor pressure increases the etching rate of the ZnS film.

The effect of the second invention of the present invention is that by using a mixed gas of a compound containing a methyl group and an inert gas as an etching gas, ions of the inert gas are converted into a reaction product Zn (CH3
) 2, the etching rate of the ZnS film is higher than that of the resist film of the mask material, and the selectivity to resist (
This improves the etching speed of the ZnS film/the etching speed of the resist film.

EXAMPLE A dry etching method according to an embodiment of the present invention will be described below with reference to the drawings.

The structure of a dry etching apparatus for carrying out the dry etching method according to the first embodiment of the present invention is the same as that shown in FIG. 2, which is a conventional dry etching apparatus.

In the first embodiment of the present invention, CH3OH was flowed through a gas supply hole connected to a means for introducing etching gas. The etching sample is a ZnS film on a Galanu substrate.
000 people are formed, and a resist film (
Positive type) was applied to a thickness of 2 μm, and a mask pattern was formed by normal exposure and development. The etching conditions are as follows.

Etching gas: CH3OH: 40SCCM (first embodiment of the present invention) C
C14:40SCCM (conventional example) CC14+o2:40SCCM+6SCCM (conventional example)
CF4+02:40SCCM+5SCCM (conventional example)C
CII +CHF3:40SCCM+20SCCM(
Conventional example) Regarding the dry etching method under etching conditions such as etching pressure = B □ mTorr high frequency power = 350W (1, sW/d) electrode distance = 75M electrode temperature = 60°C or more, Table 1 below is used to describe the dry etching method. Explain the results.

Table 1 shows the etching rate and resin selectivity of the ZnS film when the etching gas was changed under the above etching conditions. As is clear from Table 1, when CH3OH is used as the etching gas, the etching rate and resist selectivity of the ZnS film increase. As described above, according to this embodiment, by using CH3OH as an etching gas for a compound having a methyl group in dry etching of a ZnS film, ZnS
The etching rate of the film and the selectivity to resist can be improved.

Table 1 A second embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing the etching rate and resist selectivity of a ZnS film in a dry etching method according to a second embodiment of the present invention. The structure of the dry etching apparatus is similar to that of the conventional example shown in FIG. The difference from the first embodiment of the present invention is that a mixed gas of CH3OK and Ar is used as the etching gas. Other etching conditions are the same as in the first embodiment of the present invention.

FIG. 1 shows the etching rate and resist selectivity of the ZnS film when the mixing ratio of CH3OH and Ar was changed under the above etching conditions.

As is clear from Figure 1, CH3 is used as the etching gas.
Using a mixed gas of OK and Ar, Ar addition amount g5vo1%
In the following, the etching rate and resist selectivity of the ZnS film become larger.

As described above, according to this embodiment, as the etching gas in the dry etching of the ZnS film, CH3OH is used as the gas of the compound having a methyl group, and Ar is used as the inert gas.
By using a mixed gas of , it is possible to improve the etching rate of the ZnS film and the selectivity to resin. In particular, by using a mixed gas of CH3OH and Ar as compared to a CH3OH gas alone, the selectivity to resist can be improved and a resist film can be used as a mask material.

In addition, in the first and second examples, the etching gas, which is a compound having a methyl group, was CHOH, but the etching gas may be any compound as long as it generates a methyl group by glow discharge. Of course it's a good thing.

Furthermore, in the second embodiment, the inert gas was Ar;
Similar effects were obtained when He was used as the inert gas.

Effects of the Invention As described above, according to the first invention of the present invention, Zn
In the dry etching of the S film, by using a compound having a methyl group as the etching gas, Zn
The etching rate and resist selectivity of the S film can be improved, and the effects are significant, including application to electroluminescent display manufacturing processes.

However, according to the second aspect of the present invention, by using a mixed gas of a compound having a methyl group and an inert gas as an etching gas in dry etching of a ZnS film, compared to the case of using only a compound having a methyl group, Furthermore, the etching rate and selectivity to resist of the ZnS film can be further improved, and a sufficiently inexpensive and simplest resist film can be used as a mask material.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the etching characteristics of a dry etching method according to a second embodiment of the present invention, and FIG. 2 is a diagram showing the configuration of a conventional dry etching apparatus and a dry etching apparatus used in the present invention. 1... Vacuum vessel, 3... Electrode, 4...
...Object to be etched, 6...High frequency power supply,
6...Gas supply hole, 8...Plate electrode. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
figure

Claims (6)

[Claims] (1) A dry etching method characterized in that a ZnS film is processed by the generated ions and radicals by discharging a gas of a compound having a methyl group. (2) The dry etching method according to claim 1, wherein the compound having a methyl group is CH_3OH. (3) A dry etching method characterized in that a ZnS film is processed by the generated ions and radicals by discharging a mixed gas of a compound having a methyl group and an inert gas. (4) The compound having a methyl group is CH_3OH,
The dry etching method according to claim 3, wherein the inert gas is Ar. (5) The dry etching method according to claim 3 or 4, characterized in that a gas containing a compound having a methyl group and 95 vol% or less of an inert gas is used. (6) The dry etching method according to claim 5, wherein the inert gas is Ar.