Deep diffusion zone prodn. in doped semiconductor - by applying second dopant or non-dopant around zone before thermal treatment, avoiding lateral spread

摘要

Prodn. of deep diffusion zones in a doped semiconductor substrate is effected by introducing a first dopant through a maks into the surface of the substrate, followed by diffusion during thermal treatment. The novel feature is that (a) a second dopant is introduced into the surface through a second doping mask, with windows complementary to (part of) the lateral boundaries or (b) a dopant or (c) non-dopant is introduced over the entire surface, before thermal treatment. Pref. the concn. of the second dopant is much higher than that of the first. Pref. the substrate is p-Si, the first dopant P or As, the second dopant (a) B, Al or Ga, (b) In and the non-dopant (c) a noble gas.