Real-time spectroscopic ellipsometry study of the thermal cleaning process for silicon epitaxial growth by uhv-cvd

摘要

Real-time spectroscopic ellipsometry (RTSE) method was applied to study thermal cleaning process of silicon surfaces for epitaxial growth by ultra-high vacuum chemical vapor deposition (UHV-CVD). For the first time, in-situ observation of oxide decomposition process under Si_2H_6 ambience was carried out. The substrates with thin oxide formed by wet chemical treatment were heated up by infrared heater under UHV or under Si_2H_6 ambience in an UHV-CVD chamber and the oxide decomposition processes were observed by RTSE. Ellipsometric parameters Psi and Delta increase with the progress of oxide decomposition process and become constant with the completion of the decomposition. It was found that the oxide decomposition process consists of two phases and rate-determing processes are different in each phase. It was also found that Si_2H_6 lowers the activation energies of oxide decomposition process in each phase.