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. ß-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.