Evaluation of Carbon Filter Module Systems to Control Arsine and Phosphine Emissions During Accidental Release Scenarios

The semiconductor industry presently uses arsine and phosphine as dopants in the production of silicon-based semiconductors. The substances have been designated by the United States Environmental Protection Agency as being both “hazardous air pollutant” and “extremely hazardous substances”. Thus, Special engineering considerations are required to address potential environmental concerns related to the use and storage of these substances. However, despite the utilization of state-of-the-art engineering controls, the potential for accidental release scenarios still exist. This carbon filter study was designed to evaluate various issues concerning the appropriateness of utilizing this type of control technology, when applied to prevent and minimize environmental and health consequences resulting from the accidental release of arsine or phosphine into the atmosphere. Evaluations were conducted to assess the ability of carbon to remove arsine at inlet concentrations ranging from approximately 0.5 to 1000 ppm/v. Removal efficiency and adsorption capacity studies were conducted on carbon filter units designed to handle gas volumetric flow rates at approximately 50 and 1000 acfm. To evaluate the effect that “aging” exerts on carbon media, a test program was conducted to assess the remaining adsorption capacity of carbon filter units which were utilized at Bell Laboratories facilities for time periods ranging up to 2 years. These 1,000 acfm rated units were challenged with arsine at a design concentration of approximately 200 ppm/v. Studies were also performed to assess the ability of carbon to remove phosphine at inlet concentrations ranging from 50 to 600 ppm/v. removal efficiency and adsorption capacity studies were conducted on a carbon filter unit designed to handle a gas volumetric flow rate of 1000 acfm. A phosphine ignition study was additionally conducted to determine phosphine levels that would ignite when exposed to air, and to document flame characteristics and downstream phosphine concentration.