A NONISOTHERMAL FILM MODEL FOR MASS-TRANSFER-LIMITED SELECTIVE EPITAXIAL-GROWTH OF SILICON ON PATTERNED SURFACES

A two-dimensional film model for mass-transfer-controlled selective ep itaxial growth (SEG) of Si on bare and regularly patterned wafers was developed, and the effects of bulk gas composition, pressure, substrat e temperature, thermal diffusion, and oxide coverage were analyzed. SE G rates decrease with a lower concentration of the source gas and with the addition of HCl, which eventually leads to etching. The effects o f pressure and substrate temperature on mass-transfer-limited SEG rate s are determined by the way in which the equilibrium composition at th e deposition surface depends on these variables. Thermal diffusion con tributes to larger net fluxes away from the deposition surface. The ef fect of thermal diffusion is to inhibit SEG rates at lower bulk HCI co ncentrations and to extend the growth region to higher bulk HCI concen trations. Higher oxide coverages produce higher deposition rates with reduced mass transfer limitations. These model predictions are qualita tively consistent with reported observations.