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Details

Safe Removal of Arsenic Dust from Gallium Arsenide Crystal Pullers.

PB97105068

Publication Date	1995
Personal Author	Ware, R.; Puechner, R.; Tiernan, M.
Page Count	19
Abstract	A chemical cleaning process was developed for liquid encapsulated Czochralski crystal pullers which would reduce the exposure of the operators to arsenic (7440382). In this process the arsenic would be transferred from the puller to a container without releasing arsenic dust into the atmosphere. The arsenic could be converted to arsenic-trichloride which will be carried off in a stream of argon gas into a suitable scrubber. Provided precautions were taken to remove residual moisture from the insulation by vacuum baking and keeping the heater temperature below 500 degrees-C, arsenic could be successfully removed from the puller without any attack on the stainless steel components. Molybdenum-chloride formation was avoided by replacement of molybdenum parts by insert materials such as graphite and alumina. Chloride attack on the crystal occurred even when it was raised to the highest possible position. The authors suggest that the process must be operated by removing crystal and crucible before chlorine transport of the arsenic. While the major exposure to arsenic could be avoided, it appears that some exposure is inevitable during removal of the crystal.
Keywords	Industrial hygiene Occupational safety and health Control technology Semiconductors Arsenic compounds Crystal pullers
Source Agency	National Institute for Occupational Safety and Health
NTIS Subject Category	57U - Public Health & Industrial Medicine 68G - Environmental Health & Safety 94H - Industrial Safety Engineering
Corporate Authors	Ware Technical Services, Inc., Westwood, MA.; National Inst. for Occupational Safety and Health, Cincinnati, OH.
Supplemental Notes	Sponsored by National Inst. for Occupational Safety and Health, Cincinnati, OH.
Document Type	Technical Report
Title Note	Final rept. 1 Oct 94-31 Mar 95.
NTIS Issue Number	199701

Safe Removal of Arsenic Dust from Gallium Arsenide Crystal Pullers.

Safe Removal of Arsenic Dust from Gallium Arsenide Crystal Pullers.
PB97105068

Publication Date	1995
Personal Author	Ware, R.; Puechner, R.; Tiernan, M.
Page Count	19
Abstract	A chemical cleaning process was developed for liquid encapsulated Czochralski crystal pullers which would reduce the exposure of the operators to arsenic (7440382). In this process the arsenic would be transferred from the puller to a container without releasing arsenic dust into the atmosphere. The arsenic could be converted to arsenic-trichloride which will be carried off in a stream of argon gas into a suitable scrubber. Provided precautions were taken to remove residual moisture from the insulation by vacuum baking and keeping the heater temperature below 500 degrees-C, arsenic could be successfully removed from the puller without any attack on the stainless steel components. Molybdenum-chloride formation was avoided by replacement of molybdenum parts by insert materials such as graphite and alumina. Chloride attack on the crystal occurred even when it was raised to the highest possible position. The authors suggest that the process must be operated by removing crystal and crucible before chlorine transport of the arsenic. While the major exposure to arsenic could be avoided, it appears that some exposure is inevitable during removal of the crystal.
Keywords	Industrial hygiene Occupational safety and health Control technology Semiconductors Arsenic compounds Crystal pullers
Source Agency	National Institute for Occupational Safety and Health
NTIS Subject Category	57U - Public Health & Industrial Medicine 68G - Environmental Health & Safety 94H - Industrial Safety Engineering
Corporate Authors	Ware Technical Services, Inc., Westwood, MA.; National Inst. for Occupational Safety and Health, Cincinnati, OH.
Supplemental Notes	Sponsored by National Inst. for Occupational Safety and Health, Cincinnati, OH.
Document Type	Technical Report
Title Note	Final rept. 1 Oct 94-31 Mar 95.
NTIS Issue Number	199701