Characterization of the HCl Absorption & Outgassing Mechanisms by FOUPs' Polymers

Abstract

The HCl absorption and release by FOUP polymers was characterized through the determination of its solubility and diffusion coefficients in PC and PEEK in clean room conditions (21{degree sign}C and 40% humidity). For the first time, HCl diffusion coefficients were determined (D = 2.9 +/- 1.7 x 10-9 cm².s-1 in PC and D = 1.4 +/- 0.8 x 10-9 cm².s-1 in PEEK). These experimental data were then applied. First, the HCl concentration profiles in a FOUP's PC wall depending on the contamination time were calculated showing that HCl migrates until 0.5 mm thickness in less than 16h, but also that the full crossing is likely unreachable in an industrial context. Second, the efficiency of usual cleanings were evaluated depending on the temperature or time. For FOUP materials saturated in HCl, relatively low HCl rate (<35%) were determined even for high process temperature.