Dependence of chemical composition and bonding of amorphous SiC on deposition temperature and the choice of substrate

Amorphous SiC has superior mechanical, chemical, electrical, and optical properties which are process dependent. In this study, the impact of deposition temperature and substrate choice on the chemical composition and bonding of deposited amorphous SiC is investigated, both 6 in. single-crystalline Si and oxide covered Si wafers were used as substrates. The deposition was performed in a standard low-pressure chemical vapour deposition reactor, methylsilane was used as the single precursor, and deposition temperature was set at 600 and 650 degrees C. XPS analyses were employed to investigate the chemical composition, Si/C ratio, and chemical bonding of deposited amorphous SiC. The results demonstrate that these properties varied with deposition temperature, and the impact of substrate on them became minor when deposition temperature was raised up from 600 degrees C to 650 degrees C. Nearly stoichiometric amorphous SIC with higher impurity concentration was deposited on crystalline Si substrate at 600 degrees C. Slightly carbon rich amorphous SiC films with much lower impurity concentration were prepared at 650 degrees C on both kinds of substrates. Tetrahedral Si-C bonds were found to be the dominant bonds in all deposited amorphous SiC. No contribution from Si-H/Si-Si but from sp(2) and sp(3) C-C/C-H bonds was identified. (C) 2010 Elsevier BM. All rights reserved.