An attempt to specify thermal history in CZ silicon wafers and possibilities for its modification

The term thermal history of silicon wafers represents the whole variety of process parameters of crystal growth. The aim of this contribution is an attempt to specify thermal history by one parameter that is directly correlated to the bulk microdefect density. The parameter that reflects thermal history and correlates it with nucleation of oxide precipitates is the concentration of VO2 complexes. The VO2 concentration in silicon wafers is too low to be measured by FTIR but it can be obtained from the loss of interstitial oxygen during a standardized thermal treatment. Based on this, the vacancy concentration frozen during crystal cooling in the ingot can be calculated. RTA treatments above 1150 °C create a well defined level of the VO2 concentration in silicon wafers. This means that a well controlled modification of the thermal history is possible. We also investigated the kinetics of reduction of the as-grown excess VO2 concentration during RTA treatments at 950 °C and 1050 °C and the effectiveness of this attempt to totally delete the thermal history.