Organosilicon compounds are commonly used as precursors in chemical vapor deposition (CVD) of SiC film. The gas phase pyrolysis studies of organosilicon precursors are useful for understanding SiC film productions. As potential precursors, thermal decomposition of allyltrichlorosilane and allyltrimethylsilane at temperatures up to 1340 K were studied using flash pyrolysis coupled with molecular beam sampling and vacuum ultraviolet single-photon ionization time-of-flight mass spectrometry (VUV-SPI-TOFMS). The initial reaction of allyltrichlorosilane was homolysis of the Si-C bond, producing SiCl3 and C3H5 radicals. The SiCl3 radical then underwent sequential Cl losses to form :SiCl2, SiCl and Si. The C3H5 radical also underwent secondary reactions, producing a series of C3Hx species (m/z = 39-42), consistent with previous studies. In the pyrolysis of allyltrimethylsilane, molecular elimination reaction forming Me2Si=CH2 + C3H6 and Si-C bond ruptures producing Me3Si + C3H5 and Me2SiCH2CH=CH2 + CH3 were identified as the main initiation decomposition steps. HSiMe3 was also identified as one of the initiation reaction products. The observed secondary reactions of Me2Si=CH2 and Me3Si were consistent with previous studies. Possible thermal decomposition mechanism of the Me2SiCH2CH=CH2 product was also proposed.

Thermal decomposition mechanism of Allyltrichlorosilane and Allyltrimethylsilane

ACS Spring Meeting 2021

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