Precipitation of iron in multicrystalline silicon during annealing

In this paper, the precipitation kinetics of iron in multicrystalline silicon during moderate temperature annealing are systematically studied with respect to annealing time, temperature, iron super-saturation level, and different types and densities of precipitation sites. The quantitative analysis is based on examining the changes in the concentrations and distributions of interstitial iron in multicrystalline silicon wafers after annealing at 400–700 °C. This is achieved by using the photoluminescence imaging technique to produce high-resolution spatially resolved images of the interstitial iron concentrations. The concentrations of interstitial iron are found to decrease exponentially with the annealing time. Comparison of the precipitation time constants of wafers annealed at different temperatures and of different initial interstitial iron concentrations indicates that higher levels of iron super-saturation result in faster precipitation processes. The impact of iron super-saturation on the precipit...