Analysis of Relationship between Inorganic Gases and Fine Particles in Cleanroom Environment

Abstract

The concentrations and characteristics of major components in inorganic gases and fine particles were measured at the photo and etch cleanroom areas in a Taiwan semiconductor factory. The results showed that the major inorganic gases, as expressed in terms of volume concentration, were NH(3) and HF at 7-10 and 4-6 ppbv, respectively. The average PM(2.5) mass concentration were 17.52 and 18.23 mu g/m(3) at the photo and etch areas, respectively, with species of Na(+), NH(4)(+), Cl(-) and SO(4)(2-) had the highest concentrations in the PM(2.5) mass. And the inorganic species account for 56% and 62% of the particulate mass, respectively, at the photo and etch areas. Relatively stronger correlations were observed between NH(4)(+) and SO(4)(2-) with the correlation coefficient R(2) of 0.62 and 0.82, respectively, at the photo and etch areas; this indicates their common source was possibly from the gas to particle formation process. And NH(3) was found to co-exist with HF at the etch area due to their common source as process chemicals (NH(4)OH and HF) in the wet bench. In the predominant NH(3)-rich environment, ammonia is the basic neutralizing agent to form the ammonium aerosol in a cleanroom.