Heat treatment process for wafers

Abstract

In order to form a film on a surface of a semiconductor wafer, a multiplicity of wafers are individually mounted on ring-shaped mounts of a wafer boat, while the temperature within a reaction tube is set at, e.g., 400.degree. C. under a nitrogen gas atmosphere. After loading the wafer boat into the reaction tube, the temperature within the reaction tube is raised up to, e.g., 620.degree. C. at a rate of, e.g., 100.degree. C./min, and SiH.sub.4 gas is supplied onto the surface of a silicon substrate to form a polysilicon film. After film formation, air is forced to flow along the internal surface of the heating section to forcibly cool the interior of the reaction tube. In the case of forming a metal silicon film using a wafer having a silicon substrate and a metal film formed on the surface of the silicon substrate, the temperature within the reaction tube is set at, e.g. 100.degree. C. for loading the wafers. This suppresses the growth of a natural oxidation film and improves characteristics of a semiconductor device. The same principle may apply to an oxide film formation and an impurity dispersion.