Slip Length in Silicon Wafers Caused by Indentation during Heat Treatment

The relationship between the length of slip dislocation and applied stress in silicon wafers was investigated. Czochralski (CZ) silicon wafers [boron-doped, interstitial oxygen concentration [Oi]=(13.8–14.0)×1017/cm3], indented by a Vickers hardness tester, were thermally stressed by insertion into and withdrawal from a horizontal furnace. The length of slip dislocations generated during the heat treatment was measured by X-ray topography (XRT). To estimate the applied thermal stress during the heat treatment, temperature distribution in the wafer was measured with a thermocouple. From the results of XRT observations, slip dislocations were found to be generated at peripheral and central regions during the insertion and the withdrawal, respectively. The length of slip dislocations was calculated using the experimentally estimated thermal stress. It was found that the length of slip dislocation could be explained well by the model, with consideration of the applied stress and the dislocation velocity.