Determination of the denuded zone in Czochralski-grown silicon wafers through MOS lifetime profiling

A technique is presented that can determine whether a denuded zone exists in Czochralski-grown silicon wafers and, if so, how deep into the substrate it extends. Measurements taken after oxygen out-diffusion and precipitation anneals show agreement with denuded zone measurements taken using section topography and angle lapping/ chemical etching. The defect mechanisms that are being monitored by this technique include enhanced thermal generation due to defect states. They also include increased electron-hole pair generation due to impact ionization, which is caused by distortion of the potential lines near precipitates (oxide and/or metal precipitaties). Another defect mechanism, injection of unannihilated thermal donors, is shown to be less significant.