Patent ID: 6593629
Filing Date: 2003-07-15
Classification: H01L

Abstract:
A semiconductor device comprising:an n-type buried layer located by contacting the surface of a p-type semiconductor substrate; a p-type buried layer located by contacting the surface of said n-type buried layer; an n-type epitaxial layer located so as to cover said p-type semiconductor substrate, said n-type buried layer, and said p-type buried layer by contacting them; an n-type emitter region, a p-type base region encircling said n-type emitter region by contacting it from the inside, and an n-type collector region, which are respectively located at the surface of said n-type epitaxial layer; a p-type outer-periphery layer located at the surface of said n-type epitaxial layer, encircling said n-type emitter region, said p-type base region, and said n-type collector region from the circumference when viewed from above, wherein said n-type epitaxial layer comprises an n-type encirclement layer contacting and encircling said p-type outer-periphery layer, said p-type base region and said p-type buried layer as well as said p-type outer-periphery layer and said p-type buried layer respectively are continued to divide said n-type epitaxial layer and, separate said n-type collector region from said p-type semiconductor substrate, and moreover said n-type buried layer and said n-type encirclement layer are continued to separate said p-type buried layer, p-type base region, and p-type outer-periphery layer from said p-type semiconductor substrate, wherein: the p-type impurity concentration of said p-type base region is higher than the n-type impurity concentration of the n-type epitaxial layer forming a pn-junction with the p-type base region; and said p-type base region comprises a base-contact side base region contacting a base contact and a p-type buried-layer-side base region contacting the p-type buried layer and containing p-type impurities at a concentration lower than that of said base-contact-side base region.