Chemical reactions during plasma-enhanced atomic layer deposition of SiO_2 films employing aminosilane and O_2/Ar plasma at 50 ℃

摘要

We report the temporal evolution of surface species observed in situ using attenuated total reflection Fourier transform infrared absorption spectroscopy (ATR-FTIR) during plasma-enhanced atomic layer deposition (PE-ALD) of SiO_2 films employing aminosilane and an O_2/Ar plasma at a temperature of 50 ℃. Reversals in the appearance of IR absorbance features associated with SiO-H, C-H_x, and Si-H proved to coincide with the self-limiting reaction property in ALD. Our IR results indicate that an O_2/Ar plasma can both removed CH_x groups and transform SiH surface species to SiOH. In addition, SiO_2 deposition was confirmed by a continuous increase in Si-O absorbance with each PE-ALD step, which becomes stable after several cycles. On the basis of our results, the mechanism of low temperature SiO_2 PE-ALD was discussed.