Method for fabricating silicon carbide vertical mosfet devices

Abstract

A method of forming a vertical MOSFET device includes forming a trench within a drift layer substrate, the drift layer comprising a first polarity type, the trench generally defining a well region of a second polarity type opposite the first polarity type. An ohmic contact layer is formed within a bottom surface of the trench, the ohmic contact layer comprising a material of the second polarity type. A layer of the second polarity type is epitaxially grown over the drift layer, sidewall surfaces of the trench, and the ohmic contact layer. A layer of the first polarity type is epitaxially grown over the epitaxially grown layer of the second polarity type so as to refill the trench, and the epitaxially grown layers of the first and second polarity type are planarized so as to expose an upper surface of the drift layer substrate.

1 - 19 . (canceled) 
   
   
       20 . A method comprising:
 forming a doped drain region substrate of a first conductivity type, the drain region substrate having a top;   forming a drift layer over the drain region substrate, the drift layer comprising the first conductivity type;   forming a plurality of trenches within the drift layer, extending down to the top of the drain region substrate; and   filling the plurality of trenches by epitaxial growth of a material of a second conductivity type opposite the first conductivity type.   
   
   
       21 . The method of  claim 20 , wherein the first conductivity type is N-type silicon carbide and the second conductivity type is P-type silicon carbide. 
   
   
       22 . A device comprising:
 a drift layer formed over a drain region substrate, the drift layer and drain region comprising a first polarity type with the drain having a greater dopant concentration with respect to the drift layer;   an ohmic contact layer formed within an upper region of the drift layer, the ohmic contact layer comprising a material of the second polarity type;   a well region layer of the second polarity type formed atop the ohmic contact layer, wherein the ohmic contact layer comprises a greater dopant concentration than the well region layer;   a source layer of the first polarity type formed within the well region layer;   a gate insulating layer formed over an upper surface of the drift layer, the well region layer and the source layer;   a gate electrode contact formed over a portion of the gate insulating layer; and   a source electrode contact formed within the source layer, the well region layer and the ohmic contact layer.   
   
   
       23 . The method of  claim 20 , wherein said forming a plurality of trenches within the drift layer and filling the plurality of trenches by epitaxial growth includes forming a plurality of trenches within the drift layer and filling the plurality of trenches by epitaxial growth such that the trenches form part of a superjunction vertical MOSFET device. 
   
   
       24 . A device comprising:
 a doped drain region substrate of a first conductivity type and having a top;   a drift layer over the drain region substrate, the drift layer comprising the first conductivity type; and   a plurality of regions within the drift layer, each region extending down to the top of the drain region substrate and including a material of a second conductivity type opposite the first conductivity type.