Gas-phase reaction chemistry of 1,1-dimethyl-1-silacyclobutane as a precursor gas in the hot-wire chemical vapor deposition process — Formation of tetramethylsilane and trimethylsilane

Abstract

The secondary gas-phase reaction products of 1,1-dimethyl-1-silacyclobutane (DMSCB) and its isotopomer, 1,1-di(perdeuteratedmethyl)-1-silacyclobutane (DMSCB-d6), in a hot-wire chemical vapour deposition reactor were investigated using vacuum UV laser single photon ionization with time-of-flight mass spectrometry. Dimethylsilylene, one of the primary decomposition products, undergoes π-type addition across the double and triple C–C bond and an insertion reaction into the Si–H bond. A short-chain reaction mechanism, initiated by methyl radicals produced in the primary decomposition, is found to exist for both the source DMSCB molecule and its stable secondary products. The formation of tetramethylsilane and trimethylsilane via the reaction of 1,1-dimethylsilene with a methyl radical and an H2 molecule, respectively, has been demonstrated. These are two new reaction channels involving 1,1-dimethylsilene in secondary gas-phase reactions.