Process for the preparation of an ideal oxygen precipitating silicon wafer having an asymmetrical vacancy concentration profile capable of forming an enhanced denuded zone

摘要

A process for heat-treating a single crystal silicon wafer to influence the precipitation behavior of oxygen in the wafer in a subsequent thermal processing step. The wafer has a front surface, a back surface, and a central plane between the front and back surfaces. In the process, the wafer is subjected to a heat-treatment to form crystal lattice vacancies in the wafer. During the heat-treatment, the front and back surfaces of the wafer are each exposed to either a nitriding gas or a non-nitriding gas. The front surface of the heat-treated wafer is then oxidized by heating in the presence of an oxygen-containing atmosphere in order to further effect the vacancy concentration profile within the wafer. The wafer is then cooled from the temperature of said heat treatment at a rate which allows some, but not all, of the crystal lattice vacancies to diffuse to the front surface to produce a wafer having a vacancy concentration profile determined in part by the gas to which each surface is exposed, in part by the surface oxidation and in part by the cooling rate.