Simulation of vacancy agglomeration based on ab initio calculations and comparison with experimental results

Formation energies and the equilibrium concentrations of vacancy clusters were determined by ab initio calculation. They were used in rate equation modeling of vacancy agglomeration. It was found by kinetic modeling that vacancy clusters formed in rapid thermal annealing (RTA) pre-treated wafers are rapidly dissolved during anneals at temperatures larger than 700 degrees C. This can explain the loss of the getter efficiency in RTA pre-treated low oxygen wafers after annealing at temperatures >700 degrees C. Hexavacancies are the species which would appear in the highest concentration after RTA pre-treatment according to its high binding energy. These ring-like vacancy clusters are assumed to be able to getter metallic impurities. (C) 2014 The Japan Society of Applied Physics