JP2001308068A - Method of cleaning chamber of etching apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of cleaning, with which AlF3 deposited on the inner wall of a chamber of an etching apparatus can be adequately removed. SOLUTION: In the inside of the chamber 1 of an etching apparatus, a first step of performing H2O plasma processing and following the first step, and a second step of performing Cl2 plasma processing, are executed after executing an Al dry etching process. The deposited substance AlF3 is decomposed into Al(OH)3 by the H2O plasma, made to change into Al(Cl)3 by the Cl2 plasma, and exhausted to the outside of the vacuum chamber 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for cleaning the inside of a chamber of a plasma etching apparatus.

[0002]

2. Description of the Related Art Generally, dry etching of aluminum (Al) is performed in a process of manufacturing a semiconductor device. Dry etching of Al is usually performed using Cl ₂ , BC
is performed using the l _3, CHF ₃ plasma.

However, when dry etching of Al is performed using these plasmas, AlF ₃ is mainly deposited on the inner wall of the chamber of the etching apparatus. As the number of Al etching processes increases with an increase in the number of processed wafers, the thickness of the deposited AlF ₃ increases.

When the film thickness of AlF ₃ increases, the AlF ₃ film eventually peels off from the inner wall of the chamber onto the wafer, causing a short circuit in the wiring of the wafer.

Conventionally, the AlF ₃ film peeled off from the inner wall of the chamber as described above has been removed by opening the chamber at regular intervals and performing wet cleaning on the inside of the chamber. However, A peels off
If the amount of the lF ₃ is increased, the cycle of wet cleaning is shortened, the operation rate of the etching apparatus results in a lowered.

In order to solve such a problem, many chamber cleaning methods have been proposed.

For example, Japanese Patent Publication No. 2-12818 discloses that
A method for removing oxides or deposits generated by etching or ashing using hydrogen plasma has been proposed.

Further, Japanese Patent Application Laid-Open No. 6-302565 discloses
A method of cleaning a chamber using plasma of an organic compound gas containing at least hydrogen has been proposed.

Japanese Patent Application Laid-Open No. Hei 10-261623 proposes a method of performing dry cleaning using plasma of a mixed gas of boron and chlorine.

Japanese Patent Application Laid-Open No. H11-330055 proposes a method of cleaning a chamber by using a plasma of a halogen gas.

[0011]

However, according to any of the above-mentioned methods, the Al deposited on the inner wall of the chamber is not always possible.
F ₃ could not be sufficiently removed, and the problem due to AlF ₃ peeling off from the inner wall of the chamber still remained unresolved.

The present invention has been made in view of this point, and has been made in consideration of the fact that Al deposited on the inner wall of a chamber of an etching apparatus.
And to provide a chamber cleaning process which makes it possible to sufficiently remove F _3.

[0013]

SUMMARY OF THE INVENTION In order to achieve this object,
Therefore, the present invention relates to a plasma etching apparatus in a chamber.
In the method of cleaning the part, the Al dry etch
After the _TwoFirst process to perform O plasma treatment
Then, following the first step, Cl 2_TwoPlasma processing
A cleaning method characterized by comprising two steps.
provide.

It has been found that AlF ₃ as an etching product deposited on the inner wall of the chamber of the etching apparatus easily reacts with water (H ₂ O) and is decomposed into Al (OH) ₃ . In the cleaning method according to the present invention, first, AlF ₃ is decomposed into Al (OH) ₃ by H ₂ O plasma, then changed to Al (Cl) ₃ by Cl ₂ plasma, and then exhausted to the outside of the chamber. I do. AlF ₃ is not exhausted because of its low vapor pressure and adheres to the inner wall of the chamber, but Al (Cl) ₃ can be exhausted to the outside of the chamber because of its high vapor pressure. For this reason, AlF ₃ is converted to Al (C
l) By changing to ₃ , A as an etching product deposited on the inner wall of the chamber of the etching apparatus
lF ₃ can be efficiently removed.

[0015]

FIG. 1 is a schematic diagram of a dry etching apparatus for AlCu wiring for performing a cleaning method according to an embodiment of the present invention. This dry etching apparatus is an ICP type low pressure high density plasma etcher.

The dry etching apparatus shown in FIG. 1 includes a vacuum chamber 1 provided with a gas introduction line 6 and a gas exhaust line 7, a lower electrode 3 disposed at the bottom of the vacuum chamber 1, And a bias RF power supply 5 for applying a bias voltage to the lower electrode 3.

The dry etching apparatus having such a structure operates as follows.

The wafer 2 to be processed is fixed on the lower electrode 3 in the vacuum chamber 1 by electrostatic attraction.

Although not shown, a heater is embedded in the lower electrode 3 so that the temperature of the lower electrode 3 can be freely adjusted.

An etching gas is supplied to the inside of the vacuum chamber 1 through a gas introduction line 6.

From the source RF power supply 4, the vacuum chamber 1
Is supplied with high-frequency power, and plasma is generated inside the vacuum chamber 1. Bias RF power supply 5 to lower electrode 3
Is applied to the wafer 2 to be processed anisotropically, and the wafer 2 to be processed can be etched.

The etching products and gases generated after the reaction are exhausted through a gas exhaust line 7.

The structure of the AlCu wiring as an etching target formed on the wafer to be processed 2 includes a resist, a TiN antireflection film, an AlCu film, and a TiN / Ti
The order is barrier film, plasma oxide film.

The etching gas Cl _2, BCl _3, furthermore, a system with the addition of CHF ₃ as Al sidewall protective gas.

The etching of the AlCu wiring was performed in two steps. That is, in the main etching step, AlCu
The film and the underlying TiN / Ti barrier film were etched, and then the underlying oxide film was etched in an over-etch step to completely separate the wiring within the wafer surface and to suppress short-circuiting between wirings.

The reaction products generated by etching include compounds mainly composed of carbon contributed by resist, and Al generated by reaction between Al and Cl _2.
Cl ₃ , and also AlF ₃ generated by the reaction between Al and CHF ₃ .

These etching products 8 are deposited on the inner wall of the vacuum chamber 1.

From the EDX analysis of the deposit 8 attached to the inner wall of the vacuum chamber 1, it is found that peaks of Al and F appear. That is, Al reacts mainly with Cl ₂ ,
Although AlCl ₃ is generated, AlCl ₃ is exhausted without adhering to the inner wall of the chamber because of its high vapor pressure. On the other hand, A
When l reacts with CHF ₃ , it becomes AlF ₃ ,
It is considered that F ₃ adheres to the wiring side wall before being exhausted to the outside of the chamber due to its low vapor pressure and forms a side wall protective film, and also adheres to the inner wall of the chamber to cause deposition.

As the number of etching processes increases, the thickness of the deposit 8 on the inner wall of the vacuum chamber 1 increases. As a result of evaluating the dependence of the number of particles on the number of Al-etched wafers, the number of particles increased rapidly after etching about 1,000 sheets, and when the etching of about 1,000 sheets was completed, the deposited film thickness became excessive.
It is considered that the deposit 8 peeled off. Normally, wet cleaning of the inside of the vacuum chamber 1 is required at the stage when a particle abnormality occurs.

Hereinafter, the dry cleaning method according to the present embodiment will be described. The dry cleaning is to insert an etching recipe for removing the deposit 8 on the inner wall of the vacuum chamber 1 after performing Al etching to some extent.

In this embodiment, the dry cleaning process is performed after performing 50 Al etchings.
Here, the interval between the number of Al processed sheets does not need to be 50, and can be set to an arbitrary number.

The dry cleaning gas is H ₂ O,
It was used with the plasma turned on. AlF ₃ , the main component of the deposit 8, is easily hydrolyzed to Al (OH) ₃ by H ₂ O plasma. However, although the deposited film 8 becomes brittle due to hydrolysis, Al (OH) ₃ has a low vapor pressure, and thus remains attached to the inner wall of the vacuum chamber 1 at this stage.

Therefore, as a second step, Al (OH) ₃ is changed to AlCl ₃ by Cl ₂ plasma treatment. AlCl ₃ is a reaction product at the time of ordinary Al etching, and is exhausted because of its high vapor pressure.

As described above, by changing the film quality of the deposit 8 inside the vacuum chamber 1, the deposit 8 can be removed and the increase in the thickness of the deposit 8 can be suppressed.

By performing the dry cleaning method according to the present embodiment, the number of Al-etched sheets before the number of particles rapidly increased was 2,000 or more. As described above, in the case where the dry cleaning method according to the present embodiment is not performed, the number of Al-etched treatments until the number of particles rapidly increases is about 1,000, and therefore, the dry cleaning method according to the present embodiment provides:
It has been found that the deposit 8 can be efficiently removed.

As an etcher for etching the AlCu wiring, another plasma method such as EGR type and RI
The same dry cleaning process as in the above embodiment was performed using the E type. As a result, even when another plasma method was used, the same dry cleaning effect as in the above-described embodiment was obtained.

Further, the same dry cleaning treatment as in the above embodiment was performed by using CH ₂ F ₂ instead of CHF ₃ as a side wall protection gas for the Al wiring etching gas. Also in this case, since AlF ₃ becomes the deposited film 8 on the side wall of the vacuum chamber 1, a dry cleaning effect similar to that of the above-described embodiment was obtained.

[0038]

According to the cleaning method of the present invention, it is possible to suppress an increase in the film thickness of the deposits deposited on the inner wall of the chamber, and it is possible to keep the number of particles low, and to reduce the number of particles of Al wiring. Since a short circuit can be suppressed, the yield can be improved.

Further, since the wet cleaning cycle can be extended, the operating rate of the etching apparatus can be increased.

[Brief description of the drawings]

FIG. 1 is a schematic view of an etching apparatus for performing a cleaning method according to an embodiment of the present invention.

[Description of Signs] 1 Vacuum chamber 2 Wafer to be processed 3 Lower electrode 4 Source RF power supply 5 Bias RF power supply 6 Gas introduction line 7 Gas exhaust line 7 8 Deposit

Claims (1)

[Claims] 1. A method of cleaning the chamber interior of the plasma etching apparatus, after Al dry etching step, a first step of performing of H ₂ O plasma treatment, subsequent to the first step, first performs Cl ₂ plasma treatment A cleaning method comprising two steps.