Low Pressure Chemical Vapor Deposition of Silicon Carbide from Ditertiarybutylsilane

This study investigates the use of ditertiarybutylsilane as a single precursor to synthesize amorphous SiC films by low pressure chemical vapor deposition at temperatures below 850°C. The deposition rate is observed to vary linearly with the square root of flow rate and pressure. In the temperature range of 600 to 675°C, the deposition rate follows an Arrhenius behavior with an activation energy of 24 kcal mol*¹, while above 675°C, it seems to be controlled by the homolytic cleavage of the Si-C bonds and mass–transfer limitations. The carbon content is seen to progressively increase with higher temperatures with a particularly rapid rate noted above 750°C. The hardness and the Young's modulus increase as the deposition temperature is raised reaching maximum values close to 20 and 200 GPa, respectively, at 750°C. The addition of NH₃ is noted to improve significantly the optical transmission of the deposits while adversely impacting the film stress. In the temperature range between 810 and 850°C, free-standing membranes were produced using the chamber pressure to optimize stress.