Formation of pnp bipolar structure by thermal donors in nitrogen-containing p-type Czochralski silicon wafers

The carrier concentration profile in boron-doped p-type nitrogen-containing Czochralski silicon wafer subjected to a one-step high-temperature (1150 °C) annealing followed by a prolonged 450 °C annealing has been investigated by spreading resistance profile. It is found that the carrier concentration profile is characteristic of a pnp bipolar structure, while, that in the control wafer of p-type conventional Czochralki silicon subjected to the identical thermal treatment is just characteristic of a p-n junction. Moreover, it is suggested that only one-step annealing at high temperatures is an efficient method for intrinsic gettering of a nitrogen-containing Czochralski silicon wafer due to the outdiffusion of oxygen and nitrogen in the near-surface region and the nitrogen-enhanced oxygen precipitation in the bulk region.