Application of routes to silicon-carbon bond formation for production of precursors to advanced materials: Part I: Investigation of cyclic and linear carbosilanes as single-source CVD precursors to silicon carbide. Part II: Synthesis and characterizat

Part I. The low pressure chemical vapor deposition (LPCVD) of silicon carbide (SiC) from the single-source carbosilane precursors methyl silane (CH3SiH3), 1,3-disilabutane (CH3 SiH2CH2SiH3) (nDSB), 1,3-disilacyclobutane ([SiH2CH2]2) (DSCB) and 1,3,5-trisilacyclohexane ([SiH2CH2]3) (TSCH) has been investigated in an effort to determine the effect of the precursor's structure on its pyrolytic conversion to SiC. Deposits were produced between 700 and 1100°C at 5 mTorr with each of the precursors. The gas phase pyrolysis products were examined as well as the growth rate, composition, morphology and crystallinity of the resultant SiC deposits. Polycrystalline beta-SiC has been produced using each of the precursors at temperatures as low as 800°C. Reactive molecular beam scattering spectroscopy (RMBSS) and in-situ Auger electron spectroscopy (AES) were employed to examine the surface pyrolysis of DSCB and nDSB. The precursors were found to have a low decomposition probability (<5%) up to 1100°C on a single collision with the Si(100) surface.; Part II. Synthetic routes to fluoro and cyano substituted poly(silylenemethylenes) (PSMS) [-SiXX' CH2-]n (X = F, CN, CH3) have been developed. These polymers are analogs of poly(vinylidenedifluoride) (PVDF), a polymer which displays useful piezo- and pyroelectric activity. The resultant fluoro- and cyano-substituted PSMs have been characterized by using solid state nuclear magnetic resonance spectroscopy, differential scanning calorimetry, fourier transform infrared (FTIR) spectroscopy, and x-ray powder diffraction. An essentially fully substituted [-SiF2CH2-] n polymer was found to exhibit crystallinity, with the polymer chains in the all-trans conformation, analogously to the electrically active form of PVDF. The polymer melts reversibly at around 170°C and undergoes thermal rearrangement above 300°C. An essentially fully substituted [-Si(CH 3)(CN)CH2-] was prepared and has a Tg of 33°C, while only a partially disubstituted cyano-PSM polymer (47% Si(CN) 2 units) was obtained. However, this partially dicyano substituted PSM exhibits a powder x-ray diffraction pattern, indicating that it is partially crystalline.