Purification of methylsilanes

Details Purification of methylsilanes Purification of methylsilanes

2000-09-19

2002-09-03

Smith, Duane S. (Department: 1724)

Gas separation: processes

Solid sorption

Inorganic gas or liquid particle sorbed

C095S139000, C095S141000

Reexamination Certificate

active

06444013

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to processes for purifying methylsilane. More particularly, the present invention provides for purifying and condensing methylsilane gas through cryogenic adsorption techniques.
BACKGROUND OF THE INVENTION
Organosilicon gases, particularly methylsilane are employed in the semiconductor industry as coatings and films. A typical process for producing methylsilanes is called the “direct process.” This is the reaction of methyl chloride and silicon in the presence of a copper catalyst. The effluent from the reactor, however, is still a mixture of methylsilanes and high boiling materials such as disilanes, polysiloxanes, silylmethylenes and the like. This effluent must then be distilled to separate the methylsilane from the other silanes present.
Additionally, these synthesis methods also result in the generation of olefinic and chlorinated hydrocarbons. These individual species can cause separation problems with the above-mentioned distillation process, as well as problems relating to color and stability of the resulting product.
A typical sample of methylsilane gas may find various impurities in it that can interfere with the use of methylsilane in semiconductor fabrication and processing. These impurities include for example hydrogen, nitrogen, argon, oxygen, methane, ethane, carbon dioxide, silane, chlorosilane and dimethylsilane.
Applicants have discovered that the use of a cryo-adsorption process will remove impurities, particularly chlorosilanes and carbon dioxide, better than processes such as distillation.
SUMMARY OF THE INVENTION
The present invention provides for a process for the purification of methylsilane. The process provides for the steps of providing a source of methylsilane containing impurities, directing the methylsilane to an adsorption vessel for adsorption and degassing and directing the purified methylsilane to a collection vessel.
The adsorption vessel will contain an appropriate adsorbent such as magnesium silicate and will be kept at a temperature of about −40° C.
The impurities typically found in methylsilane gas are hydrogen, nitrogen, argon, oxygen, methane, ethane, carbon dioxide, silane, chlorosilane and dimethylsilane.


REFERENCES:
patent: 4099936 (1978-07-01), Tarancon
patent: 4224040 (1980-09-01), Gazzarrini et al.
patent: 4461908 (1984-07-01), Takamizawa et al.
patent: 4554141 (1985-11-01), Scull et al.
patent: 4774347 (1988-09-01), Marko et al.
patent: 4976944 (1990-12-01), Pacaud et al.
patent: 4985580 (1991-01-01), Chadwick et al.
patent: 5051117 (1991-09-01), Prigge et al.
patent: 5206004 (1993-04-01), Park
patent: 5290342 (1994-03-01), Wikman et al.
patent: 5493042 (1996-02-01), Ault et al.
patent: 5493043 (1996-02-01), Marko et al.
patent: 5916245 (1999-06-01), Tom
patent: 5961695 (1999-10-01), Hasegawa et al.
patent: 5980608 (1999-11-01), Dietz et al.
patent: 6027547 (2000-02-01), Tom et al.
patent: 0 812 849 (1997-12-01), None
Masud Akhtar, “Preparation of Ultra-High Purity Higher Silanes and Germanes,” SYNTH. REACT. INORG. MET.-ORG. CHEM., 16(5), 729-748 (1986).

Affiliated with

Also associated with

Rating

Purification of methylsilanes does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Purification of methylsilanes, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Purification of methylsilanes will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2907366