Patent ID: 6376891
Filing Date: 2002-04-23
Classification: H01L

Abstract:
A semiconductor device comprising:a semiconductor substrate of a first conductivity type comprising a primary surface including a first portion and a second portion; a buried diffusion region of a second conductivity type comprising a first surface and a second surface, said first surface in contact with said first portion of the primary surface of said semiconductor substrate; and an epitaxial layer of the second conductivity type comprising, a high breakdown voltage isolation region contacting said second portion of said primary surface of said semiconductor substrate, and having a thickness and an impurity concentration consistent with a reduced surface electric field, Resurf, condition such that the high breakdown voltage isolation region exhibits a reduced surface electric field effect, Resurf effect, and a low breakdown voltage element region adjoining said high breakdown voltage isolation region and contacting said second surface of said buried diffusion region, said low breakdown voltage element region having an element formed thereon, wherein an impurity concentration of a region of said epitaxial layer in said low breakdown voltage element region being higher than an impurity concentration of said epitaxial layer in said high breakdown voltage isolation region, said low breakdown voltage element is formed in said region of said epitaxial layer having an impurity concentration higher than said high breakdown voltage isolation region, and said high breakdown voltage isolation region isolates said low breakdown voltage element region from a high voltage element region, and a characteristic of the element is not adversely affected by a source of high voltage in the high voltage region.