Method of producing epitaxial wafers

Abstract

The invention relates to a method of producing epitaxial wafers for the manufacture of high integration density devices capable of showing stable gettering effect. Specifically, it provides (1) a method of producing epitaxial wafers which comprises subjecting a silicon wafer sliced from a single crystal ingot grown by doping with not less than 1×10 atoms/cm of nitrogen to 15 minutes to 4 hours of heat treatment at a temperature not lower than 700° C. but lower than 900° C. and then to epitaxial growth treatment. It is desirable that the above single crystal ingot have an oxygen concentration of not less than 11×10 atoms/cm . Further, (2) the above heat treatment is desirably carried out prior to the step of mirror polishing of silicon wafers. Furthermore, (3) it is desirable that the pulling rate be not increased in starting tail formation as compared with the pulling rate of the body in growing the above single crystal ingot. By taking these means, it is possible to produce epitaxial wafers having an almost constant, high level of gettering effect irrespective of the site of wafer slicing from the single crystal ingot and, furthermore, suppress the occurrence of defects within the epitaxial layer.