The Origin of Nonuniform Growth of LPCVD Films from Silane Gas Mixtures

Abstract

A mathematical model that provides a unified treatment of growth of LPCVD films from silane mixtures is in agreement with experimental results from several investigators. The effects of pressure, flow rate, and reactor geometry on within‐wafer and wafer‐to‐wafer uniformity are predicted by the model. Numerical simulations of the effect of wafer boat and cage design on the uniformity of growth are presented. It is shown that for a crossflow reactor, in which the gases flow parallel to the wafer surfaces, convection makes a negligible contribution to the transport of species. The role of homogeneous reactions in the growth of in situ doped polysilicon, silicon dioxide, and SIPOS films is discussed with reference to model results.