JPH0342824A - Reaction gas for etching - Google Patents

Abstract

PURPOSE:To enable a title item to be superb in etching rate and cleanness and deviation of selection ratio after etching and then to be miniaturized by using a mixed gas of at least one kind selected from CHCl2CF3, CH3CCl2F, CH2FCF3, and CHCl2F as a reaction gas. CONSTITUTION:A wafer 4 is set onto a table 5 within a chamber 3 and then a reaction gas, namely a mixed gas with at least one kind selected from SF6, CHCl2CF3, CH3CCl2F, CH2FCF3, and CHCl2F is introduced into a chamber 3 from a reaction gas supply source 9. At this time, blending ratio of the latter group of gas is set to 5-95vol.%.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a reactive gas used for etching the surface of a sample such as a semiconductor wafer.

(Prior Art) As one of the manufacturing processes for LSI chips, a method has conventionally been adopted in which a mask is formed on the surface of a semiconductor wafer and the portions not covered by the mask are etched using a reactive gas.

Specifically, Special Publication No. 50-9545 or Special Publication No. 5
As disclosed in Publication No. 3-34462, etching can be carried out efficiently by setting a sample in a microwave plasma space, introducing a reaction gas, and applying a magnetic field to the plasma space. The technology is known.

CJZ2, CF4. Freon gases such as SF6 and mixtures of these gases are used, but SF6+C2CJ is preferred in terms of processing accuracy, etching rate, uniformity, and selectivity.
2 sFs (Freon 113), C2C mutual. F4 is widely used.

(Problems to be Solved by the Invention) Recently, there has been a demand for higher density LSI chips, and for this reason, it has become essential to have a reaction gas that has better properties than conventional reactant gases, and Freon 113 and C2Cj2
, F4 is also considered to be a factor in ozone layer depletion, so
There is a high possibility that production will be prohibited and it will no longer be possible to use it.

(Means for Solving the Problems) In order to solve the above problems, the present invention uses etching reaction gases of SF6 and CHCfl2CF5. CI(3CCj2
The gas was mixed with at least one selected from 2F, CH2FCh and CHCl2F, and the ratio of the latter group of gases was 5 to 95vO196.

(Action) CICjZ 2cFs, CHsCCIt 2F, CH2
By using a mixed gas of SF6 and at least one selected from FCF3 and C) ICj22F as a reactive gas, better results than conventional C2cJ2sFs can be obtained in terms of etching rate, selectivity, and contamination on the substrate. can get.

(Example) Embodiments of the present invention will be described below based on the accompanying drawings.

FIG. 1 shows an example of an apparatus for performing etching using a reactive gas according to the present invention. A table 5 on which a wafer 4 as a sample is placed is provided in the chamber 3, and the table 5 is connected to a high frequency power source 6 of 13.55 MHz. Further, the inside of the chamber 3 is connected to a vacuum pump 8 via a valve 7 so that the inside of the chamber 3 can be brought into a high vacuum state, and a reaction gas supply source 9 is provided inside the chamber 3.
to the reactive gas according to the present invention, namely SF.

and C) IcI 2cFs, (:LC(:422F,C
A mixed gas with at least one selected from H2FCF3 and CHI2F is introduced.

Further, the chamber 3 is surrounded by a waveguide 10, and the chamber 3 is surrounded by a waveguide 10,
6) Microwaves from the microwave oscillator 11 of Iz (therefore, the inside of the chamber 3 is used as a discharge space, that is, a plasma generation space, and a coil 12 that generates a magnetic field in a direction perpendicular to the microwave electric field is installed outside the waveguide 10). It is placed.

A specific example using the etching apparatus configured as described above will be described below.

The flow rate of the mixed gas with a 1:1 mixing ratio of Aiou Seal SF, C) IC, and e2Ch was 36 sec, the microwave output was 200 W, the high frequency output was 100 W, and the degree of vacuum was 6 mTo.
When polysilicon was etched under rr conditions,
The etching speed was 5000 people/min, and anisotropic etching with no deposits on the surface was obtained.

Furthermore, the etching speed when etching a silicon oxide film instead of polysilicon is as shown in Figure 2.
FIG. 2 also shows the relationship between the etching rate and the mixing ratio of SF6 and CHi 2C:F, and the selective etching ratio with respect to the polysilicon oxide film.

These results show that the present invention has excellent etching speed and selective etching ratio, and has no deposits such as particles on the substrate.
It was confirmed that this is a highly practical etching gas.

In place of CHCJZ2CF in Example 1, (:H
3CCJ2 zF, C) I2FCh, CHI, l12F
Similar results were obtained using .

Inuwaritan SF, 10 sccm, C) ICj22F, 20
Microwave output 200 while flowing at sccmQ rate
When polysilicon was etched under the conditions of W, high-frequency output of 100 W, and vacuum level of 8 mTorr, the etching rate was 2,600 people/11in, the uniformity was 3%, and etching with excellent anisotropy was obtained.

Example 4 C1 in Example 3 (CHCJ12F 10 sccm instead of J 2F 20 sec, CHCJZ
Polysilicon was etched under the same conditions except that 2CF3 was used at sccm, but there was no difference in the etching results.

C2CJ2 instead of C) lcj22F in Shiotanman Example 3
When 3 hours were used, particles were observed to adhere to the polysilicon surface after etching.

Judging from the above, SF8 and CHCJ12Ch
.

CHsCCu 2F, C) 12FCF3 and CHCu
, F is superior to conventional mixed gases, and the blending ratio of the gas selected from the latter group is preferably 5 to 95 vo.

(Effects of the Invention) As explained above, the reaction gas for etching according to the present invention is superior to conventional reaction gases in terms of etching rate, cleanliness after etching, and selectivity, and is suitable for further refinement. It is advantageous in terms of safety because it can sufficiently respond to the needs of customers, has less dirt in the processing chamber, enables clean processing, and is also advantageous in terms of safety.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an etching apparatus, and FIG. 2 is a graph showing the relationship between gas mixing ratio, etching rate, and selective etching ratio when using the reactive gas according to the present invention. In the drawing, 3 is a chamber, 4 is a wafer, 8 is a vacuum pump, 9 is a reactant gas supply source, 11 is a microwave oscillator,
12 is a coil. Patent applicant: Tokyo Ohka Kogyo Co., Ltd. Agent
Person Patent Attorney Part 2 1) Yong-Immediate Question Patent Attorney
Kuni Ohashi Patent Attorney Koyama Ministry Figure 2

Claims (1)

[Claims] In the etching reaction gas introduced into the chamber where the sample is set, this reaction gas contains SF_6 and CH
Cl_2CF_3CH_3CCl_2F, CH_2FC
A reactive gas for etching, characterized in that it is a mixed gas with at least one selected from F_3 and CHCl_2F, and the proportion of the latter group of gases is 5 to 95 vol%.