POST-DIFFUSION GETTERING EFFECTS INDUCED IN POLYCRYSTALLINE SILICON

Large grain polycrystalline silicon wafers have been subjected to post -annealing (900 degrees C/45 min) after POCl3 pre-diffusion at differe nt temperatures. For the first-time we have investigated the effect of the furnace starting and quenching temperature on the gettering effic iency. The optimisation of thermal cycle parameters include the determ ination of the best combination of starting temperature, of post-annea ling, heating rate, cooling rate, postannealing temperature (duration) , quenching temperature and POCl3 diffusing condition result in an inc rease by 275% of the minority carrier diffusion length. The second adv antage of this post-annealing is the improvement of the homogeneity of activated phosphorus distribution and of the electrical properties.