Influence of temperature gradients on partial pressures in a lowhyphen;pressure chemicalhyphen;vaporhyphen;deposition reactor

摘要

Measurements and calculations of the influence of temperature gradients on the partial pressures of the gas species in a coldhyphen;wall chemicalhyphen;vaporhyphen;deposition reactor are presented. The experiments were performed at low pressures (300ndash;500 Pa total pressure) and gas mixtures consisting of hydrogen, nitrogen, and tetrafluoromethane. The partial pressures were determined by Raman spectroscopy. The Soret effect (or thermal diffusion) has a large influence on the partial pressures of heavy gases in the vicinity of the heated wafer. In some cases a decrease in partial pressure of 20percnt; compared to the inlet partial pressures was observed. Numerical calculations were performed to predict the behavior of the gas mixture. For mixtures under investigation the gas temperatures as well as the changes in partial pressures due to the Soret effect were predicted correctly.