JPH0936085A - Cleaning of dry etching device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently dissociate or eliminate a residual bromine product containing carbon particle by generating plasma in a chamber where a cleaning gas consisting of a specific gas is introduced into an etching chamber using such gas as hydrogen bromide. SOLUTION: An upper electrode 4 and a lower electrode 3 are arranged oppositely in a chamber 1 and a high-frequency power supply 5 is connected to the upper electrode 4. A wafer 6 is set on the lower electrode 3, is clamped by a clamping plate 7, and is subjected to dry etching using hydrogen bromide gas, thus attracting carbon or bormine particle P generated in the chamber 1. To clean the chamber 1, CF4 /O2 mixed gas is filled into the chamber 1 and a plasma is generated, where the makeup ratio between the CF4 gas and O2 gas is 5vol.%-45vol.% of CF4 gas and 95vol.%-55vol.% of O2 gas.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of cleaning a dry etching apparatus, and more particularly to a method of dry cleaning an etching apparatus which has performed dry etching using hydrogen bromide and helium gas.

[0002]

2. Description of the Related Art A conventional technique relating to a dry etching apparatus is O ₂ for ashing carbon particles.
Plasma cleaning, a plasma cleaning method using SF ₆ as disclosed in JP-A-5-144786, or 2% by volume to 5% by volume of CF ₄ as disclosed in JP-A-6-20975. , O ₂ is 9
For example, plasma cleaning is performed by introducing 8% by volume to 95% by volume of CF ₄ / O ₂ gas. These methods have a decompression chamber for generating O ₂ , SF ₆ plasma or CF ₄ / O ₂ plasma, a high frequency power source, and a gas flow rate adjusting mechanism.

[0003]

However, although cleaning with O ₂ plasma has a function of ashing and removing carbonaceous particles, when bromine gas is used as an etching gas, it adheres and deposits in the etching chamber. The residual bromine product thus obtained could not be sufficiently dissociated and removed, and the residual bromine product might become particles to cause pattern defects on the device during the next treatment. Similarly, in the case of cleaning with SF ₆ plasma or CF ₄ / O ₂ plasma,
Since generation of particles due to residual bromine products could not be suppressed, wet cleaning had to be performed in a short cycle.

The present invention has been made in view of the above-mentioned problems of the prior art, and its main purpose is to efficiently remove residual bromine products generated when bromine gas including carbon particles is used. It is an object of the present invention to provide a method for cleaning a dry etching apparatus which can be dissociated or removed.

[0005]

According to the present invention, the above object is achieved by containing 5% by volume to 45% by volume of C in the chamber of an etching apparatus for etching using a gas such as hydrogen bromide.
It is achieved by providing a cleaning method for a dry etching apparatus, characterized in that a plasma is generated in the chamber while a cleaning gas consisting of F ₄ gas and 95% by volume to 55% by volume of O ₂ gas is introduced. It

[0006]

DETAILED DESCRIPTION OF THE INVENTION] CF ₄ / O ₂ gas CF ₄ gas 5
% To 45% to generate plasma, for example, a Si-Br-based product is converted into a compound or radical of Si and F by F radical or the like,
A --Br-based product is removed as an F radical, a C--Br-based product is removed as a compound or radical of C and F by an F radical or the like, and C is removed as an O radical as CO ₂ . An example of the reaction is shown below.

[0007]

Embedded image SiBrF ^* → SiF ^* ↑ + Br ↑ CBr + F ^* → CF ^* ↑ + Br ↑ C + 2O ^* → CO ₂ ↑

If the CF ₄ gas content is 5% or less,
F radicals are less likely to be generated, the residual bromine product cannot be efficiently dissociated and removed, and if it exceeds 45%, not only the residual bromine product is not particularly easily removed, but also

[0009]

[Chemical formula 2] CF ₄ + O ₂ → CO ₂ ↑ + F ^*

As a result, the F radicals generated are reduced, and the O radicals are reduced, so that it is difficult to remove carbonaceous particles.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will now be described in detail with reference to the accompanying drawings.

FIG. 1 is a sectional view of an etching apparatus to which the present invention is applied. This etching device is equipped with an upper electrode 4
The lower electrode 3 and the lower electrode 3 are arranged to face each other in the chamber 1, and the high frequency power source 5 is connected to the upper electrode 4. Lower electrode 3
When the wafer 6 is set on the top, clamped by the clamp plate 7, and dry-etched using hydrogen bromide gas, carbon-based or bromine-based particles P generated in the chamber adhere as shown in FIG.

When cleaning this, the chamber 1 is filled with a CF ₄ / O ₂ mixed gas to generate plasma. Here, the composition ratio of CF ₄ gas and O ₂ gas is CF
₄ gas 5% by volume to 45% by volume, O ₂ gas 95% by volume to 55%
Volume% In this embodiment, CF ₄ gas 20% by volume, O ₂
The gas was 80% by volume. Also, the CF ₄ / O ₂ gas pressure is 350
mTorr, RF power 250W, frequency 13.56M
Cleaning was carried out for 5 minutes at a flow rate of 15 Hz and a CF ₄ / O ₂ gas flow rate of 15/35 ccm. The reaction of this plasma cleaning is as follows:

[0014]

[Chemical Formula 3] CF ₄ + O ₂ → CO ₂ ↑ + F ^*

By the above, F ^* is efficiently generated,

[0016]

Embedded image SiBr + F ^* → SiF ^* ↑ + Br ↑ CBr + F ^* → CF ^* ↑ + Br ↑

The reaction of (1) proceeds efficiently and the brominated product is removed. The carbon dissociated from bromine is

[0018]

[Chemical 5] C + O ₂ → CO ₂ ↑

It is removed by the reaction of. By the above mechanism, the particles and residual bromine products in the chamber 1 are efficiently removed.

FIG. 2 shows the CF ₄ / O ₂ (CF ₄ : 5 of this embodiment.
% -45%) The number of particles of 0.25 μm or more on the silicon substrate before and after cleaning with a gas is indicated by a solid line. In addition, as a reference example, before and after cleaning with a conventional SF ₆ / O ₂ gas or CF ₄ / O ₂ (CF ₄ : 2% to 5%
%) The number of particles before and after cleaning with gas is indicated by a wavy line. In the past, the number of particles was reduced from about 300 to about 220 and the removal rate was about 27%, whereas in the present embodiment, the number of particles was reduced from about 300 to about 20 and the removal rate was about 93%. Has become.

FIG. 3 shows the CF ₄ gas content and removal rate (the number of particles removed by cleaning / the number of particles before cleaning) when performing plasma cleaning with CF ₄ / O ₂ gas. As is clear from this graph, the CF ₄ gas content is 5% by volume to 45% by volume.
It can be seen that the particle removal rate is remarkably high in the range.

[0022]

As is apparent from the above description, according to the cleaning method of the dry etching apparatus of the present invention, the CF ₄ / O ₂ gas having a CF ₄ gas content of 5% by volume to 45% by volume is used. By introducing and performing plasma cleaning, not only the carbon-based particles in the etching chamber but also residual bromine products that have been deposited and deposited can be efficiently dissociated and removed, the quality of the etching target is improved, and wet cleaning of the etching apparatus is performed. Since the implementation interval can be lengthened, the operating efficiency of the etching apparatus is also improved.

[Brief description of drawings]

FIG. 1 is a sectional view of an etching apparatus before cleaning to which the present invention is applied.

FIG. 2 is a graph showing the cleaning effect according to the present invention and the prior art.

FIG. 3 is a graph showing the relationship between the CF ₄ gas content and the removal rate when performing plasma cleaning with CF ₄ / O ₂ gas.

[Explanation of symbols]

 1 Chamber 3 Lower Electrode 4 Upper Electrode 5 High Frequency Power Supply 6 Wafer 7 Clamp Plate P Bromine-based Product or Carbon-based Particle

Claims (1)

[Claims] 1. A cleaning gas comprising 5% by volume to 45% by volume of CF ₄ gas and 95% by volume to 55% by volume of O ₂ gas in a chamber of an etching apparatus for performing etching using a gas such as hydrogen bromide. A method for cleaning a dry etching apparatus, characterized in that plasma is generated in the chamber in the state of introducing.