Precipitation and crystallization of nanometer Si clusters in annealed Si-rich SiO₂ films

Si-rich SiO₂ films with three different degrees of Si-richness were deposited by RF magnetron sputtering using Si-SiO₂ composite targets. X-ray photoelectron spectroscopy measurements indicate that Si clusters were present in the as-deposited films. The precipitation and crystallization of nanometer Si clusters in SiO₂ films annealed at high temperatures have been studied using high-resolution transmission electron microscopy and electron diffraction. Si nanocrystallites were observed in the sample deposited using a Si-SiO₂ composite target having a 30% area of Si and which had been annealed at 900 °C. The average size and density of Si nanocrystallites in the films increased notably as the annealing temperature was increased from 900 to 1100 °C. Thus, using a 1100 °C anneal and increasing the area percentage of Si in the composite target from 20 to 30%, the average size of Si nanocrystallites increased about 15%, and the density of Si nanocrystallites increased by a factor of about 2.5.