On-site Fluorine Chamber Cleaning for Semiconductor Thin-film Processes: Shorter Cycle Times, Lower Greenhouse Gas Emissions, and Lower Power Requirements

摘要

Regular removal of thin-film deposits in chemical vapor deposition (CVD) reaction chambers is an important requirement in semiconductor manufacturing technology. Most often plasma etching using fluorine-containing gases like sulfur hexafluoride SF_6 and nitrogen trifluoride NF_3 is widely applied, because of the efficient reactions of fluorine radicals with the residues and the high volatility of the resulting fluoride products. Concerns have been expressed, however, about the global warming impact of such gases: SF_6 and NF_3 exhibit global warming potentials of 22,600 and 17,200 times that of CO_2 as measured over 100 years [1] [2]. While previous work has shown that NF_3 may be preferred to SF_6 because of a gas utilization near 100% for small area scale reactors [3], significantly lower gas usage was measured for commercial reactors. Weiss et al. estimate that 16% of the global production of NF_3 is released in the atmosphere, with atmospheric concentration rising 11% per year [4]