Microstructure and growth of SiC film by excimer laser chemical vapour deposition at low temperatures

Abstract

The formation of SiC film by photo-chemical vapour deposition (CVD) using ArF excimer laser with a wavelength of 193 nm has been studied to establish a low-temperature and mild synthetic process for ceramic films. Photo-CVD was conducted using Si2H6 and C2H2 as source gases on quartz glass, molybdenum and graphite substrates at 508–623 K. The pressure ratio of Si2H6 to C2H2 was changed from 0.06 to 1.2. The laser was irradiated at 50 mJ cm−2 at 25 Hz. The films were identified using transmission electron microscopy and infrared spectrometry, and the chemical composition was determined using Auger electron specroscopy. The growth rate of SiC was measured with a step-height profilometer. s-SiC, with almost stoichiometric composition, was formed in the pressure ratio range, Si2H6/C2H2, of 0.06–1.2 at 508–623 K. Crystallization of the SiC film was observed with increasing Si2H6/C2H2 ratio. The film growth rate linearly depended on Si2H6 pressure but was independent of C2H2 pressure. The rate-determining step of film formation is assumed to be photolysis of Si2H6. The cross-section of photolysis calculated from the film growth rate was about 10−18 cm2 for the ArF laser.