Kinetics and uniformity of deposition of borophosphosilicate glass from silane and oxygen in a single-wafer reactor

We have characterized the average rate of deposition and radial variation of film thickness for boron- and phosphorus-doped silica glasses deposited in a prototype single-wafer chemical vapor deposition system, using multifactor experimental designs to elucidate efficiently the effects of various process parameters. The overall deposition rate is found to be approximately linear in the input flow of silane, with the conversion efficiency influenced by the dopant gases, temperature, and pressure. Unlike most previous workers, we have found the O sub(2):SiH sub(4) ratio to have only a weak influence on the deposition rate. The radial variation of thickness has been studied by varying the distribution of input gases between the center and edge inlets in the reactor. The average deposition rate is found to be interpretable by first-order reaction kinetics when the relative contributions of transport by diffusion and removal of reactants by the pump are taken into account.