Oxygen transportation during Czochralski silicon crystal growth

Abstract

Oxygen transportation processes concerning CZSi crystal growth have been investigated, including dissolution from silica crucible to silicon melt, evaporation from silicon melt to ambient Ar atmosphere and incorporation (segregation) from silicon melt to silicon crystal. It is found that almost all of the dissolved oxygen evaporates as the form of SiO from the surface of the silicon melt to the atmosphere of Ar gas in a conventional CZSi crystal growth. The quantity of the oxygen incorporated into the silicon crystal is only a very small amount compared to the dissolved oxygen or evaporated oxygen. The equilibrium segregation coefficient of oxygen was obtained by comparing the oxygen concentration in the silicon crystal to the oxygen saturation concentration in the silicon melt and the result is suggested to be 0.8±0.1. It is confirmed experimentally that the oxygen distribution in the CZSi crystal becomes much uniform and the oxygen concentration decreases gradually with increasing the cusp magnetic field, which indicates that the application of a cusp magnetic field is an effective method to control the convection in the silicon melt.