Bipolar integrated circuit pnp transistor - has p-type substrate with p-implantation zones and n-type epitaxial layer

摘要

The pnp transistor suitable for the integrated bipolar circuit featuring a p-type substrate is ensured by the formation of an epitaxial n-type layer. The small area required for the transistor is coupled to its current capacity and its advantage is that no special step is necessary for its fabrication. The substrate I is implanted with p-type doping in zones 20-23 followed by epitaxial growth of n-type layer 2. The diffusion of p+ starts from the chip surface using a corresponding mask forming zones 25-29 which are shaped like rings around the pnp transistors. The zones are positioned so that the rising and downwardly directed diffusion fronts do not intersect. The first zone forms the collector and the second zone form the emitter.