JPS62194623A - Plasma etching method - Google Patents

Abstract

PURPOSE:To make a minute processing possible wherein an etching speed is high and quality is excellent, by performing a plasma etching which applies an etching gas being a mixed gas composed of CF4 gas, O2 gas and N2 gas. CONSTITUTION:After a sample to be etched 10 is set on a cathode electrode 9, the following process is performed; i.e. the inner part of a reaction chamber 7 is exhausted, gases CF4, O2 and N2 are introduced into the reaction chamber from gas cylinders 1, 2 and 3 via the respective flow rate controllers 4, 5 and 6, plasma is generated by applying a RF power from a RF power source 11, and etching is performed. An etching speed is increased by mixing N2 with a partial pressure ratio of 0.01-0.5 in an etching gas CF4+O2. As compared with the case where N2 is not mixed-in, the etching speed higher than about three times can be obtained, and further an excellent fine processing pattern can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for plasma etching of thin films such as amorphous silicon and amorphous silicon compounds.

(Prior Art) Conventionally, in the manufacture of semiconductor devices mainly made of amorphous silicon, 02-etching has been used as a means for selectively etching a thin film made of amorphous silicon or an amorphous silicon compound.
Plasma etching methods using carbon tetrafluoride (CF4) containing small amounts (0 to 20 inches) have been employed.

(Problems to be Solved by the Invention) However, as mentioned above, when performing plasma etching using a CF4+0□ mixed gas, large RF power must be applied to the plasma etching apparatus in order to increase the etching rate sufficiently. However, at this time, the organic resin photoresist normally used as a mask was also etched, making it difficult to achieve a sufficiently high etching selectivity between the thin film to be etched and the photoresist, making microfabrication difficult. . Therefore, in order to enable microfabrication, it is necessary to lower the RF power so that the etching selectivity mentioned above can be made sufficiently large, which has the disadvantage of slowing down the etching speed. SUMMARY OF THE INVENTION It is an object of the present invention to provide a plasma etching method that eliminates the above-mentioned drawbacks, has a high etching rate, and allows good microfabrication.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides a method for plasma etching a thin film of amorphous hydrogenated silicon or an amorphous silicon compound using a plasma etching apparatus. Plasma etching is performed using an etching gas consisting of a mixed gas of CF gas, 0□ gas, and N2 gas. This etching gas has a partial pressure ratio of 0 to a mixed gas of (CF4+0).
．． A mixture of N2 gas of 0.01 to 0.5 is desirable.

(Function) According to the present invention, since plasma etching is performed using the etching gas as described above, the etching speed can be significantly increased compared to the case where N2 gas is not included, and moreover, good microfabrication holes and turns can be obtained. It will be done.

(Embodiment) FIG. 1 is for explaining one embodiment of the present invention, and is a schematic diagram of a plasma etching apparatus for carrying out the plasma etching method according to the present invention.

In Figure 1, 1 is a CF4 gas cylinder, 2 is a gas cylinder, 3 is a N2 gas cylinder, and 4.5.6 is 1'f: gas flow rate provided corresponding to cylinders 1, 2, and 3, respectively. Controller, 7 is a reaction chamber, 8 is an anode electrode, 9 is a cathode electrode, 10 is a sample to be etched, 11 is an RF power source,
12 is an exhaust pump.

The etching process using this apparatus is performed as follows.

First, after setting the sample 10 to be etched on the cathode electrode 9, the inside of the reaction chamber 1 is evacuated to a pressure of 1.times.10 torr or less.
．． N2 gas flow controller 4°5.6
The plasma is introduced into the reaction chamber through the RF power supply 11, and RF power is applied to generate plasma to perform etching. Here, the size of both electrodes 8.9 is 380 x 380 m, and the interval between both electrodes is set to 40 meters.

FIG. 2 shows the results of etching amorphous hydrogenated silicon using the above-mentioned apparatus. Etching conditions were gas flow rate CF4190SCCM, 0210SCCM.

A pressure of 0.2 torr #RF power of 200 W was set as a fixed condition, and only the N2 flow rate was set as a variable amount. The horizontal axis in Figure 2 represents the partial pressure ratio of N2 to CF4+02, and the vertical axis represents the N2
This is the relative etching speed to the etching speed when not mixed.

As is clear from Figure 2, by mixing N2 into the CF4+0□ etching gas at a partial pressure ratio of 0.01 to 0°5, the etching rate increases, and is about three times more than when N2 is not mixed. It was possible to obtain an etching speed of 100%, and also to obtain good microfabricated "turns".

(Effect of the invention) As described above, according to the present invention, CF4+02 (here 0□
The partial pressure ratio is 0.
By performing plasma etching using an etching gas mixed with 0.01 to 0.5 N2 gas, an etching speed of approximately 3 times or more can be obtained compared to the case where N2 is not mixed. You can expect the effect of being able to obtain a mother turn.

Although amorphous hydrogenated silicon was used as a sample in the above explanation, amorphous silicon compounds such as SiN, SiC
*Similar effects can be obtained with SiO, etc.

xx Processing is possible.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a schematic diagram of a plasma etching apparatus used to carry out the plasma etching method according to the present invention, and FIG.
FIG. 3 is a diagram showing the relationship between the partial pressure ratio of F + Q) gas and N2 gas and the relative etching rate. 1...CF gas cylinder, 2...0□ gas cylinder, 3...N2 gas? 4, 5.6... Gas flow rate control 2.7... Reaction chamber, 8... Anode electrode, 9... Cathode electrode, 10... Sample to be etched, 11... RF constant Power supply 12...Exhaust pump. Patent Applicant Oki Electric Works Co., Ltd. Procedural Amendment (Touge) 62.3.23 Showa Year Month Day

Claims (2)

[Claims] (1) In a method of plasma etching a thin film of amorphous hydrogenated silicon or an amorphous silicon compound using a plasma etching device, plasma etching is performed using an etching gas consisting of a mixed gas of CF_4 gas, O_2 gas, and N_2 gas. A plasma etching method characterized by etching. (2) The plasma according to claim 1, wherein the etching gas is a mixture of (CF_4+O_2) gas and N_2 gas having a partial pressure ratio of 0.01 to 0.5. Etching method.