Abatement of hazardous ion implant gases: experimental results

The hazardous and reactive nature of the materials utilized during ion implantation generates environmental, safety, and handling challenges. Many new concerns are triggered by recent transitions from high pressure or solid dopants to SDS^TM sources and insufficient information about the nature and volume of gaseous emissions. The high total flow rates and required removal of acid and hydride gases to extremely low levels demands the use of highly efficient abatement solutions. Basic and metal oxide resins are widely recognized as an effective way to chemisorb acid and hydride gases respectively. This paper summarizes the performance of a custom designed dry scrubber during the abatement of the effluent gases released by the ion source roughing pump and cryo pumps of an Applied Materials xR-80 implanter. The scrubber was developed after extensive research that included the identification and measurement of gas species exhausted during standard implantation recipes using SDS^(R) arsine (AsH ₃), phosphine (PH₃), boron trifluoride (BF₃ ), and silicon tetrafluoride (SiF₄) dopants. The prototype consisted of a combined acid/hydride resin to provide universal abatement and the unit was retrofitted at the exhaust of each pump. Operating at the exhaust of the roughing pump under worse process conditions, acid and hydride sensors measuring the scrubber effluent streams established removal of all toxic gases below their threshold level values (TLV). Gas species released during cryo regeneration were identified and similar scrubbing efficiencies were achieved