Behavior of Oxide Precipitates in Czochralski Silicon during Crystal Growth

Abstract

During Czochralski silicon (CZ-Si) crystal growth, polyhedral oxide precipitates are formed in the high temperature range (>1000° C). In order to clarify the behavior of polyhedral precipitates in the low temperature range (<1000° C) during crystal growth, a series of simulation annealing was carried out as follows. Polyhedral precipitates were intentionally created in CZ-Si wafers by annealing at 1100° C for 16 h and then subjected to low-temperature annealing at 900° C or 700° C from 1 h to 64 h. The stress state and growth process of polyhedral precipitates in the wafers were studied by transmission electron microscopy (TEM) observations. It was found that (1) the strain around the precipitates increases considerably with annealing at 900° C within 1 h, and the precipitates generate dislocations during annealing at 900° C for between 4 h and 16 h, and (2) the growth rate of polyhedral precipitates is very low in the low temperature range. From these results, it is concluded that the polyhedral precipitates grow with very low growth rate in the low temperature range (<1000° C), and the lattice strain increases considerably around 900° C during CZ-Si crystal growth.