FTIR and Raman study of rapid thermal annealing and oxidation effects on structural properties of silicon-rich SixC1-x thin films deposited by R.F co-sputtering

Abstract

Si-rich silicon carbide (SixC1-x) thin films have been deposited by Radio Frequency (RF) co-sputtering. These films were deposited from a composite target consisting of crystalline silicon fragments regularly distributed on the surface of a pure graphite disc. The surface covered by Si fragments is about 65% of the total target surface. The deposited films were subjected to rapid (15min) thermal annealing, under inert atmosphere (Ar), at different temperatures varying from 700 to 1000°C. The influence of thermal annealing on structural properties of these films was investigated by Fourier Transform Infrared (FTIR) and Raman spectroscopy techniques. FTIR spectra obtained on the as deposited and annealed films show the presence of two mine absorption bands, which are assigned to vibrational modes of SiC and SiO bonds. The presence of SiO bonds is attributed to oxygen incorporation during the exposure of samples in the atmosphere before the analysis. Upon annealing, three significant changes occur in the SixC1-x films: a significant increase of both SiC and SiO bonds content, a decrease of the films thickness and a beginning of SiC crystallization after annealing at 1000°C. Raman spectra exhibit three bands which are assigned to SiSi, SiC and C:C vibration modes. Raman results suggest that C:C and SiSi bonds present inside the material are probably isolated or located in small clusters. Upon annealing, a crystallization of Si clusters and a graphitization of carbon clusters are observed.