Effect of heavy boron doping on oxygen precipitation in Czochralski silicon substrates of epitaxial wafers

The effect of heavy boron doping on oxygen precipitation in Czochralski sil icon substrates of epitaxial wafers has been studied with transmission elec tron microscopy observations and a preferential etching method. Prolonged i sothermal annealing between 700 and 1000 degrees C for up to 700 h was perf ormed on p/p+ (5-20 m Ohm cm) and p/p- (10 Ohm cm) wafers. It was found tha t, with an increase in boron concentration, (i) the precipitate density inc reased, and (ii) the precipitates could nucleate at a higher temperature. T he growth process of platelet precipitates was also investigated and compar ed with the process in polished p- wafers. It was confirmed that (i) precip itate growth rate in p/p+ wafers was higher than that in p- wafers, and (ii ) precipitate nucleation in p/p- wafers was delayed compared with p/p+ wafe rs. The precipitate growth in p/p+ wafers was determined to be reaction-lim ited, which differed from the diffusion-limited growth in p- wafers. (C) 20 00 The Electrochemical Society. S0013-4651(99)05-088-0. All rights reserved .