Determination of airborne organic contaminants in clean-room air by silicon powder adsorption-solvent extraction-GC/MS analysis

Abstract

Some airborne organic contaminants in clean rooms for semiconductor manufacturing are unstable with respect to heating, and are easily adsorbed by silicon wafers. Accordingly, in order to measure their concentration, we developed a method that uses silicon powder adsorbent and solvent desorption-GC/MS analysis. Various methods of desorption were examined, and it was found that the most efficient method was desorption by passing n-hexane through the adsorbents. This method was compared with thermal desorption using standard solutions of di(2-ethylhexyl)phthalate (DEHP) and 2,6-di-buthylhydroxyhydroxyphenol (BHT). Using these solutions, which are unstable against heating, compounds could be detected without any alteration by this method, although altered compounds from DEHP and BHT were detected by thermal desorption. The detection limits of DEHP, dibuthylphthalate (DBP) and di(2-ethylhexyl)adipate (DEHA) by this solvent desorption method were 2 ng/m³, 2 ng/m³ and 0.6 ng/m³ respectively. By applying this method to the evaluation of clean-room air, DEHP, DBP and DEHA were detected, ranging in concentration from 16 to 80 ng/m³.