US 7,126,191 B2 · Double-diffused semiconductor device

Abstract

A DMOSFET and a method of fabricating the same, capable of keeping a desirable level of drain voltage resistance and, at the same time, of reducing the drain resistance. In a DMOSFET configured as having a drain region composed of an epitaxial layer formed on a P-type semiconductor substrate while placing an N-type buried layer in between, and as having, in the drain region, a P-type body region having an N-type source region nested therein and a drain extraction region, formation of N-type, heavily-doped buried layers prior to the epitaxial growth is proceeded so as not to form them at least in the region under the P-type body region, and so as to make an impurity concentration in the region under the P-type body region smaller than that in the region under a drift region when viewed after the impurity is diffused by the succeeding annealing.

Claims9

Dependent claims

A double-diffused MOSFET comprising at least:

a first-conductive-type buried layer formed in a second-conductive-type semiconductor substrate;
a drain region composed of an epitaxial layer formed on said first-conductive-type buried layer;
a second-conductive-type body region formed in said drain region;
a first-conductive-type drain extraction region formed in said drain region;
a first-conductive-type source region formed in said second-conductive-type body region;
a gate electrode formed at least on a part of the region between said first-conductive-type source region and said first-conductive-type drain extraction region;
and
a drift region between said second-conductive-type body region and said first-conductive-type drain extraction region;
wherein said first-conductive-type buried layer is formed so as to have a first-conductive-type impurity concentration thereof lower in the region under said second-conductive-type body region than in the region under said drift region.

6 more elements

Dependencies are inferred from the claim text.

Double-diffused semiconductor device

Life of this patent

Double-diffused semiconductor device

Life of this patent

Abstract

Claims9