US 5,963,807 A · Silicon carbide field effect transistor with increased avalanche withstand capability

Abstract

A vertical SiC trench MOSFET power switching FET includes a gate electrode in the trench. The MOSFET adds a buried region of a first conductivity type, more heavily doped than a base layer of the first conductivity type, to the base layer except adjacent to the trench. The buried region is preferably disposed in the base layer, or between a drift layer of a second conductivity type and the base layer. The region of the first conductivity type is optionally disposed below the bottom of the trench to encourage expansion of the depletion layer of the MOSFET. A depletion-type vertical SiC MESFET of the invention includes a buried region of the first conductivity type in a base layer of a second conductivity type. A Schottky electrode on a portion of the base layer above the buried region ensures adequate expansion of a depletion layer.

Claims14

Dependent claims

A method of constructing a vertical field effect transistor, comprising:

preparing a substrate of a first conductivity type, said substrate being made of SiC;
epitaxially growing a drift layer of said first conductivity type on said substrate, said drift layer being made of SiC and doped more lightly than said substrate;
epitaxially growing a SiC base layer of a second conductivity type on said drift layer;
forming a source region of said first conductivity type in a part of a surface portion of said base layer;
forming a trench extending from a surface of said source region into said drift layer;
covering said trench with a gate insulation film;
placing a gate electrode on said gate insulation film;
and
inserting a region of said second conductivity type into a portion of said field effect transistor, said region of said second conductivity type being doped more heavily than said base layer and surrounding an area adjacent to said trench.

6 more elements

Dependencies are inferred from the claim text.

Silicon carbide field effect transistor with increased avalanche withstand capability

Life of this patent

Silicon carbide field effect transistor with increased avalanche withstand capability

Life of this patent

Abstract

Claims14