Cleaning gases and etching gases

Details Cleaning gases and etching gases Cleaning gases and etching gases

2002-05-13

2004-09-07

Olsen, Allan (Department: 1763)

Etching a substrate: processes

Gas phase etching of substrate

C216S079000, C252S079100, C510S109000, C510S188000

Reexamination Certificate

active

06787053

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a chamber cleaning gas and an etching gas More particularly, the invention relates to a chamber cleaning gas suitable for CVD equipment and an etching gas in production of semiconductor devices, wherein both gases comprise a fluorine-containing carbonyl compound having a COF group, and hardly generate substances in the exhaust gases such as CF
4
, etc, which are harmful to the environment because of being perceived as contributing to global warming.
BACKGROUND OF THE INVENTION
In conventional production process of thin film devices for semiconductor manufacturing and the like, various thin films and thick films have been formed by CVD process, etc. In forming such thin films on wafers for semiconductor device, thin film materials unfavorably stick to the inner wall of a chamber, jigs supporting an object or pipes in addition to the object to form films. Such deposits induce the cause of contaminating semiconductor products with fine particles, and thereby high quality thin films are hardly prepared and further the yield of the products is lowered. Therefore, the removal thereof is necessary occasionally. Conventionally, the removal of deposits has been conducted manually or by a cleaning gas or the like.
In semiconductors, circuit patterns are formed on various thin film materials constituting semiconductor circuits so that the partial removal of thin film materials has been conducted by gas etching.
With regard to the basic properties required for such cleaning gas or etching gas, the cleaning gas is desired to have a high cleaning rate, and the etching gas is desired to have a high rate of etching objects and high selectivity. The both gases are required not to produce harmful exhaust gases to the environment and to be friendly toward the global environment.
Conventionally, as gases for cleaning such deposits or gases for etching thin films, large amounts of fluorinated compounds such as CF
4
, C
2
F
6
, SF
6
or NF
3
have been used in processes of manufacturing semiconductors.
These fluorinated compounds, however, are stable compounds having a long atmospheric lifetime, and have a problem in that, after cleaning or etching with these gases, it is difficult to treat un-decomposed gases and the treatment cost thereof is high. These fluorinated compounds, further, have an extremely high global warming potential (100 year integration time horizon) as compared with CO
2
, for example, CF
4
has a global warming potential 6500 times greater than that of CO
2
, C
2
F
6
has 9200 times, SF
6
has 23900 times and NF
3
has 8000 times. Therefore, the fluorinated compounds have an uneasy problem of exerting an adverse influence upon the environment. On this account, the development of an alternative gas having a low global warming potential, excellent cleaning properties for silicon-containing deposits of semiconductors and etching properties for silicon-containing films has been desired.
Further, even if the cleaning gas itself has no perceptible influence to the environment, the cleaning gas is decomposed after cleaning or etching with the result that a gas having a long atmospheric lifetime and being environmentally harmful, such as CF
4
, etc, is occasionally generated. Therefore, the development of alternative gases that decomposed gases thereof exert no adverse influence upon the environment has been desired. In the light of the foregoing, it is an object of the invention to provide a gas for cleaning chambers such as CVD equipment having excellent cleaning properties to silicon-containing deposits being suitable for manufacturing of semiconductors, and an etching gas having etching properties to silicon-containing films, wherein the gases have a low global warming potential, hardly generate substances in the exhaust gases such as CF
4
, etc which are harmful to the environment and have been perceived as contributing to global warming, and further the gases have excellent exhaust gas treating properties, and easy handling.
DISCLOSURE OF THE INVENTION
The present invention is intended to solve the above problems, and the present inventors found that gases prepared by mixing a specific fluorine-containing carbonyl compound with oxygen have a low global warming potential and hardly generate substances in the exhaust gases such as CF
4
, etc which are harmful to the environment and largely affect global warming even after cleaning or etching using the gases, and the gases also have excellent cleaning properties to silicon-containing deposits and etching properties to silicon-containing films.
Thus, the present invention has been accomplished. The details are as follows.
The first chamber cleaning gas according to the present invention comprises FCOF and O
2
, and optionally other gases wherein the total content of FCOF and O
2
is in the range of 70 to 100 mol % based on the total gas amount being 100 mol %.
The mixing molar ratio of FCOF to O
2
(FCOF/O
2
) preferably satisfies the formula 1≦FCOF/O
2
≦9.
The first chamber cleaning gas of the invention may comprise CF
3
OCOF and O
2
and optionally other gases. Further, the first chamber cleaning gas may comprise CF
3
OCF
2
OCOF and O
2
, and optionally other gases.
Further, the first chamber cleaning gas of the invention may comprise at least one fluorine compound selected from the group consisting of FCOF, CF
3
OCOF and CF
3
OCF
2
OCOF, and O
2
, and optionally other gases, wherein the total content of O
2
and at least one fluorine compound selected from the group consisting of FCOF, CF
3
OCOF and CF
3
OCF
2
OCOF is in the range of 70 to 100 mol % based on the total gas amount being 100 mol %.
The second chamber cleaning gas of the invention comprises CF
3
COF and O
2
, and optionally other gases, wherein the total content of CF
3
COF and O
2
is in the range of 70 to 100 mol % based on the total gas amount being 100 mol %.
The mixing molar ratio of CF
3
COF to O
2
(CF
3
COF/O
2
) preferably satisfies the formula 0.25≦CF
3
COF/O
2
1.5.
The second chamber cleaning gas of the invention may comprise C
3
F
7
COF and O
2
, and optionally other gases, wherein the total content of C
3
F
7
COF and O
2
is in the range of 70 to 100 mol % based on the total gas amount being 100 mol %, and further, the second chamber cleaning gas may comprise CF
2
(COF)
2
and O
2
and optionally, other gases wherein the total content of CF
2
(COF)
2
and O
2
is in the range of 70 to 100 mol % based on the total gas amount being 100 mol %.
The other gases preferably comprises at least one inert gas selected from N
2
, He, Ne, Ar, Kr, Xe and Rn.
When the chamber cleaning gas contains FCOF, the other gases may contain CF
3
OCOF and/or CF
3
OCF
2
OCOF.
The chamber cleaning gas is preferably a gas for cleaning chambers of CVD equipment.
The chamber cleaning gas is preferably a gas for cleaning silicon-containing deposits, and the silicon-containing deposits preferably comprise at least one of (1) silicon, (2) a compound comprising silicon and at least one of oxygen, nitrogen, fluorine and carbon, and (3) a compound of a metal silicide having a high melting point.
The first etching gas for silicon-containing films according to the present invention comprises FCOF and O
2
, and optionally other gases wherein the total content of FCOF and O
2
is in the range of 70 to 100 mol % based on the total gas amount being 100 mol %.
The mixing molar ratio of FCOF to O
2
(FCOF/O
2
) preferably satisfies the formula 1≦FCOF/O
2
≦9.
The first etching gas for silicon-containing films of the present invention may comprise CF
3
OCOF and O
2
, and optionally other gases. Further, the first etching gas for silicon-containing films comprises CF
3
OCF
2
OCOF and O
2
, and optionally other gases.
Further, the first etching gas for silicon-containing films may comprise at least one fluorine compound selected from the group consisting of FCOF, CF
3
OCOF and CF
3
OCF
2
OCOF, and O
2
, and optionally other gases, wherein the total content Of O
2
and at least one fluorine compound selected from the group consistin

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