Modification of SiO through room-temperature plasma treatments, rapid thermal annealings, and laser irradiation in a nonoxidizing atmosphere

We have studied the modification of a-SiO thin deposited films through Ar-plasma treatment at room temperature, through heating (rapid thermal annealing), or through irradiation (uv-laser treatment), in a nonoxidizing atmosphere. Rutherford backscattering spectroscopy, reflection high-energy electron diffraction, ir-absorption, and x-ray photoelectron spectroscopy techniques have been used in combination to investigate the atomic composition and the structural and chemical nature of SiO films after various nonoxidizing treatments. We show that the as-deposited oxide is not a mixture of Si and SiO₂ and separates into phases as a result of processing. The effects of irradiation by low-energy electrons at room temperature (plasma treatment) are similar to those observed for high-temperature treatments. A possible microscopic mechanism, leading to silicon cluster growth, is proposed to explain the transition from a material rich in intermediate suboxides (as-deposited SiO) to the mixture structure (phase-separated Si and SiO₂).