Limiting factors of backside external gettering by nanocavities and aluminum-silicon alloying in silicon wafers

摘要

Float zone silicon single crystalline wafers are submitted to He ion implantations at various energy levels and fluences in the ranges 40 to 120 keV and 10~(16) to 10~(17) cm~(-2), respectively. Cavities are formed after annealing at 900 deg for 1 h in argon. Al-Si gettering results from the deposition of a backside 1 #mu#m thick Al wafer and annealing at 900 deg for 4 h in argon. The wafers are voluntarily contaminated by 10~(14) to 10~(17) cm~(-3) nickel atoms and diffusion length of minority carriers is determined by SPV technique and measured before and after gettering.