Deposition of Microcrystalline Si1-xGex by RF Magnetron Sputtering on SiO2 Substrates

Microcrystalline Si1-xGex (x similar to 0.8) films have been deposited by magnetron sputtering on SiO2 substrates. Crystallinity was evaluated by spectroscopic ellipsometry, Raman scattering, X-ray diffraction (XRD), transmission electron microscopy (TEM), and electron backscatter diffraction (EBSD). Detailed investigation of the deposition behavior revealed that crystalline phase begins to form at 300 degrees C, which roughly corresponds to half of the melting temperature of the material. At 300 degrees C, crystallinity changes with thickness, i.e., crystallinity improves as thickness increases. It was found out that this change in the crystallinity is not due to the heat up of the substrate, but is an essential phenomenon. At 350 degrees C, on the other hand, crystalline phase is formed almost from the beginning of the deposition. However, surface (<100 nm) crystallinity of the 300 degrees C sample is higher compared with 350 degrees C sample when the film thickness is more than 500 nm. Substrate bias effect was also investigated. Crystallinity of 300 degrees C sample improves while that of 350 degrees C sample degrades when RF bias power is applied to the substrate. (C) 2009 The Japan Society of Applied Physics