Deposition of SiO2 films from novel alkoxysilane/O2 plasmas

Abstract

The deposition of SiO2 films from novel alkoxysilane/O2 rf plasmas has been investigated using tetraethoxysilane and the novel alkoxysilanes, triethoxysilane, tetramethoxysilane, and trimethoxysilane. We have demonstrated that high quality SiO2 films can be deposited from each of these alkoxysilanes under similar conditions. For all precursors, film deposition rates decrease with the addition of O2. Using 20:80 alkoxysilane/O2 plasmas, film deposition rate decreases with increasing substrate temperature and plasma power, while the SiO2 film quality increases, as determined by Fourier transform infrared spectroscopy, ellipsometry, and wet etch rates. Substrate temperature appears to be the most influential deposition parameter, significantly affecting both composition and properties of the deposited SiO2 films. Measured apparent activation energies for SiO2 deposition from alkoxysilane/O2 plasmas are negative for all precursors. This suggests an adsorption/desorption-limited deposition mechanism controls film formation in all systems. Additional data for SiO2 films deposited from the halogenated alkoxysilanes triethoxyfluorosilane and triethoxychlorosilane are also presented.