DE2554426

A process for the production of a locally high inverse current amplification in a preferably double diffused or implanted inversely operated transistor which includes forming a low doped epitaxial layer of one conductivity type on a high doped semiconductor substrate of the same conductivity type, forming a high doped buried region by ion implantation in the epitaxial layer beneath the zone provided for the collector, forming a low doped second region of the opposite conductivity type, above said first region which covers an area substantially wider than said first region and forming a third high doped region in the surface of the epitaxial layer spaced above said first region and having an area smaller than said first region, the first region forming the emitter, the second region forming the base and the third region forming the collector, the second region extending to the surface surrounding said third region and partially surrounding the first region. A second low doped region may be provided as an injector by diffusing an impurity of the second conductivity type into a fourth region adjacent the surface of the epitaxial layer and laterally spaced from the second region.