A semiconductor device in which a vertical pnp-bipolar transistor is formed in
a prescribed element region on a semiconductor substrate includes: a buried n+-layer
of a high concentration formed in the prescribed element region; and a p-type collector
layer formed on the buried n+-layer. By introducing impurities that
has a larger diffusion coefficient than the buried n+-layer, the collector
layer can be formed on the buried n+-layer formed in common with other
element regions, without any special masking.
