LOW-PRESSURE CHEMICAL-VAPOR-DEPOSITION OF SILICON-CARBIDE FROM DITERTIARYBUTYLSILANE

This study investigates the use of ditertiarybutylsilane as a single p recursor to synthesize amorphous SiC films by low pressure chemical va por deposition at temperatures below 850-degrees-C. The deposition rat e is observed to vary linearly with the square root of flow rate and p ressure. In the temperature range of 600 to 675-degrees-C, the deposit ion rate follows an Arrhenius behavior with an activation energy of 24 kcal mol-1, while above 675-degrees-C, it seems to be controlled by t he homolytic cleavage of the Si-C bonds and mass-transfer limitations. The carbon content is seen to progressively increase with higher temp eratures with a particularly rapid rate noted above 750-degrees-C. The hardness and the Young's modulus increase as the deposition temperatu re is raised reaching maximum values close to 20 and 200 GPa, respecti vely, at 750-degrees-C. The addition of NH3 is noted to improve signif icantly the optical transmission of the deposits while adversely impac ting the film stress. In the temperature range between 810 and 850-deg rees-C, free-standing membranes were produced using the chamber pressu re to optimize stress.