Microstructural investigation of low temperature chemical vapor deposited 3C-SiC/Si thin films using single-source precursors

Abstract

Transmission electron microscopy (TEM) was utilized to investigate microstructures of heteroepitaxial SiC/Si films, grown from single-source precursors such as tetramethylsilane [TMS, Si(CH3)4], hexamethyldisilane [HMDS, Si2(CH3)6], and 1,3-disilabutane [1,3-DSB, H3SiCH2SiH2CH3]. In the case of TMS/H2 and HMDS/H2 samples, SiC/Si films grown at relatively high precursor concentration and/or low temperatures showed columnar grains with a high degree of epitaxial relationship with the Si substrate. Higher quality films with larger grains were observed in the case of high temperature and/or low precursor concentration samples, although a high density of interfacial voids was observed. Samples grown from pure 1,3-DSB at a low pressure showed high quality single crystalline films with few interfacial voids. It was suggested that the microstructural behavior of these films closely resembles that of the SiC films formed during the carbonization of Si surfaces by the pyrolysis of hydrocarbons, in which the nucleation rate of the film at the initial stage plays a key role. The improvement achieved during the 1,3-DSB growth is proposed to be due to the low growth pressure and the 1 : 1 ratio of Si and C associated with this precursor.