TRANSISTOR AND ITS MANUFACTURE

摘要

PURPOSE: To provide a considerably narrow and highly uniform base region by removing an oxidized part in a second layer, exposing a part of a first layer and forming a substantial base region with the exposed part of the first layer. CONSTITUTION: A layer 32 of a P-type epitaxial silicon is formed on the surface of a device. A layer 34 of epitaxial/silicon is formed on the surface, and a layer 36 of a P<++> -type epitaxial/silicon which is highly doped is formed on the surface. The epitaxial/silicon layer 36 which is highly doped is oxidized faster than the layer of epitaxial/silicon 34, which is doped more lightly than the layer and therefore the considerably fine base regions (remaining layers 32 and 34) can be formed by using oxidation and etching following it. The formation of a substantial silicon layer 3 can arbitrarily selected, and the dopant concentration of the layers 36 and 32 can be changed, so that prescribed selectivity can be obtained by oxidation and etching.