Low temperature silicon dioxide film deposition by remote plasma enhanced chemical vapor deposition: growth mechanism

Deposition mechanism of SiO2 film growth from SiH4–N2O by remote plasma enhanced chemical vapor deposition (RPECVD) has been studied. An inductively coupled-RPECVD system was used to deposit films at the temperature of 25–350 °C and deposition pressure of 0.4 Torr. From in situ gas phase analyses and film composition, we suggested the film deposition mechanism and main precursors. The gas phase species including hydrogen, oxygen and SiHx fragments are incorporated into the SiO2 film as the film precursors. SiH3, SiH2 and O* radicals are likely main gas phase species for precurosor formation. In particular, the formation and transport of silanols (SiH2O and SiH3O) are observed and oxidation mechanism of these radicals is discussed. While surface hydrogen-related bonds are observed, they can be effectively removed by surface oxidation reaction. Surface composition of deposited films is similar with gas phase species and hydrogen bonds at the growing surface can be eliminated by oxygen plasma and charged ion bombardment. At high plasma power, the deposition rate is saturated and drops off, while the density of oxidation species in the plasma continuously increases. Surface roughness of deposited films increased and shows power-law dependence on plasma power.