Metal impurity precipitates in silicon: chemical state and stability

The chemical state and the stability of metal precipitates in silicon have been studied using synchrotron-based X-ray fluorescence and absorption, Specifically, we have studied the stability and chemical nature of iron and copper impurities in single and polycrystalline silicon. In polycrystalline silicon material, we observe the presence of iron oxide or silicate precipitates at dislocations. Furthermore, our results demonstrate dissolution of copper precipitates from oxygen precipitates and their growth-related defects. Based on these results, we suggest oxygen in silicon can complex and stabilize only some metal impurities, depending on the formation energies of the metal oxide compounds. (C) 1999 Elsevier Science B.V. All rights reserved.