The influence of methane flow rate on microstructure and surface morphology of a-SiC:H thin films prepared by plasma enhanced chemical vapor deposition technique

Hydrogenated amorphous silicon carbide (a-SiC:H) films, which contain sp3 hybridized carbon phase embedded in a-SiC:H matrix were fabricated by a radio frequency (13.56 MHz) plasma enhanced chemical vapor deposition (PECVD) system with methane and silane mixture (silane diluted by H2, volume ratio: 90% H2 + 10% SiH4) as reactive precursor gases. It was found that under the deposition conditions of fixed the RF power density, pressure, deposition temperature and silane mixture flow rate, the flow rate of methane (R) had a large impact on the content of sp3 hybridized carbon phase and surface morphology of the a-SiC:H thin films. The research shows that the silicon bonding environment didn't change with increasing R and the H bonded to sp3 hybridized carbon phase mainly derived from the CHn radicals generated by decomposition of CH4 rather than H2. Simultaneously, the methane flow rates can control the deposition rate and surface morphology of the a-SiC:H films and make the films become more compact and uniform.