Use of fluorinated ketones as wet cleaning agents for vapor...

Details Use of fluorinated ketones as wet cleaning agents for vapor... Use of fluorinated ketones as wet cleaning agents for vapor...

2001-04-24

2002-05-28

Carrillo, Sharidan (Department: 1746)

Cleaning and liquid contact with solids

Processes

Hollow work, internal surface treatment

C134S002000, C134S022110, C134S022140, C134S022190, C134S036000, C134S042000

Reexamination Certificate

active

06394107

ABSTRACT:

FIELD OF INVENTION
The invention relates to the use of fluorinated ketones as wet cleaning agents for vapor reactors and vapor reactor parts.
BACKGROUND OF INVENTION
The emission of global warming gases has received worldwide attention. The goal of the Kyoto Protocol, established at the United Nations Conference on Global Warming, was to lower emissions of carbon dioxide, methane, nitrous oxide, perfluorocarbon (PFC), hydrofluorocarbon (HFC), and SF
6
to pre-1990 levels. Additionally, most manufacturers of semiconductors in the United States have signed a Memorandum of Understanding with the Environmental Protection Agency pledging to evaluate options for reducing PFC emissions.
Chemical vapor deposition chambers, physical vapor deposition chambers, and etching chambers are widely used in the semiconductor industry in connection with the manufacture of various electronic device and components. Such chambers use reactive gases or vapors to deposit, pattern, or remove various dielectric and metallic materials. Over time, undesirable deposits, typically fluoropolymers containing carbon, fluorine, hydrogen and oxygen atoms, inevitably build up on both the walls and parts of the chamber. These deposits are a source of potential contamination for the product being manufactured in the chamber and must be removed periodically. Perfluorocarbon gases such as C
2
F
6
and C
3
F
8
as well as perfluorinated nitrogen compounds such as NF
3
have been used extensively for in situ plasma cleaning of the chamber. However, these gaseous materials are extremely stable compounds that contribute to global warming and are difficult to trap or treat with gas scrubbers.
The chamber walls and components can be cleaned using various liquid chemicals. The liquid cleaning agents currently used include water, various hydrocarbons such as acetone or isopropanol, and various fluorochemicals such as perfluorocarbons, hydrofluorocarbons, and hydrofluoro ethers. Water and hydrocarbons do not readily dissolve the fluoropolymer residue. Additionally, water requires long drying times and the hydrocarbons are flammable; these are both undesirable properties for a cleaning agent. Some fluorochemicals have the potential to contribute to global warming, another undesirable property for a cleaning agent.
This invention provides a method for removing deposits that build up on the walls and parts of a chemical vapor deposition chamber, a physical vapor deposition chamber, or an etching chamber using a liquid cleaning agent comprising a fluorinated ketone. The fluorinated ketones of this invention perform as well as the liquid perfluorochemicals traditionally used in the semiconductor industry but have lower global warming potential.
SUMMARY OF INVENTION
This invention provides a method of cleaning the walls and parts of a chemical vapor deposition chamber, a physical vapor deposition chamber, or an etching chamber using a liquid cleaning agent comprising a fluorinated ketone compound containing 5 to 10 carbon atoms. The cleaning agent can be a perfluoroketone, a compound in which all of the hydrogen atoms on the carbon backbone are replace with fluorine. Alternatively, the fluorinated ketone cleaning agent can have up to two hydrogen atoms and up to two non-fluorine halogen atoms including bromine, chlorine, and iodine attached to the carbon backbone. One or more heteroatoms can interrupt the carbon backbone of the molecule. The cleaning agent can also include an auxiliary halogenated compound that is miscible with the fluorinated ketone. Preferably, the auxiliary halogenated compound is a hydrofluoroether. The cleaning agent can be applied by wiping, spraying, soaking, and the like.
DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS OF THE INVENTION
This invention provides a method of cleaning a chemical vapor deposition chamber, a physical vapor deposition chamber, or an etching chamber using a liquid cleaning agent comprising a fluorinated ketone compound having 5 to 10 carbon atoms, preferably 6 to 8 carbon atoms. The fluorinated ketones typically are liquids at room temperature with boiling points up to about 150° C. Preferably, the fluorinated ketone is a perfluoroketone.
As used herein, the term “vapor reactor” includes chemical vapor deposition chambers, physical vapor deposition chambers, and etching chambers. Such chambers use reactive gases or vapors to deposit, pattern, or remove various dielectric and metallic materials. Vapor reactors are widely used in the semiconductor industry to manufacture a variety of electronic devices and components. Typically, gaseous perfluorocarbons such as CF
4
, C
2
F
6
, and C
3
F
8
are used to etch various dielectric and metallic materials. The perfluorocarbons are usually mixed with oxygen gas and a radio frequency plasma is generated resulting in the formation of various radicals such as fluorine, carbon difluoride, carbon trifluoride, and the like. These radicals can undergo further reactions to form various fluoropolymers. The fluoropolymers deposit on the reactor walls and parts along with various other by-product of the manufacturing process. These by-products can include, for example, silicon-based residues and metallic residues such as tungsten, aluminum, and the like. Periodically, the vapor reactor needs to be cleaned to remove the fluoropolymers and other residues to avoid contaminating the product being prepared.
The traditional approach to removing the deposits has been to use various liquid cleaning agents. The liquid cleaning agents currently used include water, various hydrocarbons such as acetone or isoproponal, and various fluorochemicals such as perfluorocarbons, hydrofluorocarbons, and hydrofluoroethers. Water and hydrocarbons do not readily dissolve the fluoropolymer residue. Additionally, water requires long drying times and the hydrocarbons are flammable; these are both undesirable properties for a cleaning agent. The invention provides an alternative approach that avoids these undesirable properties in a manner that is more environmentally friendly than at least some prior approaches. The fluoropolymers and other residue that deposit on the reactor walls and parts can be dissolved using a liquid fluorinated ketone cleaning agent having 5 to 10 carbon atoms. The method of cleaning a vapor reactor can be used to partially or completely replace the conventional cleaning process with gaseous perfluorocarbons. As used herein, the term “cleaning” refers to removing the unwanted deposits that build up over time on the walls and parts of a vapor reactor.
The fluorinated ketones of the invention typically have a total of 5 to 10 carbon atoms and preferably have 6 to 8 carbon atoms. The cleaning agent can be a perfluoroketone, a compound in which all of the hydrogen atoms on the carbon backbone are replaced with fluorine. Alternatively, the fluorinated ketone cleaning agent can have up to two hydrogen atoms and up to two non-fluorine halogen atoms including bromine, chlorine, and iodine attached to the carbon backbone.
Representative examples of perfluorinated ketone compounds suitable as cleaning agents include CF
3
(CF
2
)
5
C(O)CF
3
, CF
3
C(O)CF(CF
3
)
2
, CF
3
CF
2
CF
2
C(O)CF
2
CF
2
CF
3
, CF
3
CF
2
C(O)CF(CF
3
)
2
, (CF
3
)
2
CFC(O)CF(CF
3
)
2
, (CF
3
)
2
CFCF
2
C(O)CF(CF
3
)
2
, (CF
3
)
2
CF(CF
2
)
2
C(O)CF(CF
3
)
2
, (CF
3
)
2
CF(CF
2
)
3
C(O)CF(CF
3
)
2
, CF
3
(CF
2
)
2
C(O)CF(CF
3
)
2
, CF
3
(CF
2
)
3
C(O)CF(CF
3
)
2
, CF
3
(CF
2
)
4
C(O)CF(CF
3
)
2
, CF
3
(CF
2
)
5
C(O)CF(CF
3
)
2
, CF
3
CF
2
C(O)CF
2
CF
2
CF
3
, perfluorocyclopentanone, and perfluorocyclohexanone.
Representative examples of fluorinated ketones with either one or two atoms other than fluorine attached to the carbon backbone include CHF
2
CF
2
C(O)CF(CF
3
)
2
, CF
3
C(O)CH
2
C(O)CF
3
,(CF
3
)
2
CFC(O)CF
2
Cl, CF
2
ClCF
2
C(O)CF(CF
3
)
2
, CF
2
Cl(CF
2
)
2
C(O)CF(CF
3
)
2
, CF
2
Cl(CF
2
)
3
C(O)CF(CF
3
)
2
, CF
2
Cl(CF
2
)
4
C(O)CF(CF
3
)
2
, CF
2
Cl(CF
2
)
5
C(O)CF(CF
3
)
2
, and CF
2
ClCF
2
C(O)CF
2
CF
2
CF
3
.
The fluoroketones can also contain one or more heteroatoms interupting

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