Cavity Ring-Down Spectroscopy Measurement of H(n = 2) Density in Mesoplasma for Fast-Rate Silicon Epitaxy

摘要

The absolute density of the first excited state atomic hydrogen H(n = 2) in an Ar/H_2 mixture is measured in-situ by cavity ring-down spectroscopy under mesoplasma condition. The H(n = 2) atom density is determined to be in the range of 10~(10)-10~(11) cm~(-3) and the formation of H(n = 2) having such high density is identified to be predominantly due to the associative charge exchange/dissociative recombination reactions, similar to dc-arc plasma expanding into a low-pressure vessel that have been previously reported. The local H(n = 2) atom density is found to have a linear variation with deposition rate, which indicates that high H(n = 2) atom density have a direct role in the reduction of SiHCI_3 to Si.