Residual crystalline silicon phase in silicon-rich-oxide films subjected to high temperature annealing

Structural properties of silicon rich oxide ®lms ~SRO! have been investigated by means of micro-Raman spectroscopy and transmission electron microscopy ~TEM!. The layers were deposited by plasma enhanced chemical vapor deposition using differ- ent SiH 4 /O 2 gas mixtures. The Raman spectra of the as-deposited SRO ®lms are dominated by a broad band in the region 400-500 cm 21 typical of a highly disordered silicon network. After annealing at temperatures above 1000°C in N 2 , the formation of silicon nanocrystals is observed both in the Raman spectra and in the TEM images. However, most of the precipitated silicon does not crystallize and assumes an amorphous microstructure.