Reduction of grown-in defects by high temperature annealing

This research investigated the mechanism for the reduction of grown-in defe cts in Czochralski silicon wafers by high-temperature annealing for various annealing temperatures and ambients. Annealing at 1300 degrees C in an arg on ambient could eliminate not only sur face grown-in defects crystal origi nated particles (COPs), but also bulk grown-in defects at 100 mu m depth fr om the surface. Annealing at 1200 and 1250 degrees C in an argon ambient al so eliminated COPs, but their effects on bulk grown-in defects were limited to shallower regions from the surface with lower annealing temperatures. O il the other hand, annealing in an oxygen ambient could not reduce grown-in defects even at 1300 degrees C. It is thought that removal of oxide films on the inner walls of grown-in defects is the first step in the reduction p rocess of the grown-in defects. Oxygen annealing cannot remove the oxide fi lm, but rather enlarges them, and the grown-in defects remain. Argon anneal ing can remove the oxide films, and subsequent absorption of silicon self-i nterstitials reduces the grown-in defects. (C) 2000 The Electrochemical Soc iety. S0013-4651(98)11-041-8. All rights reserved.