Semiconductor device and method for manufacturing semiconductor device

Abstract

A semiconductor device of the present invention includes a semiconductor layer, a gate trench that defines a source region of a first conductivity type in the semiconductor layer, a channel region of a second conductivity type of a lower part of the source region, a source trench that passes through the source region and the channel region, an impurity region of the second conductivity type of a bottom part and a side part of the source trench, a source electrode on the semiconductor layer, and a highly-concentrated impurity region of the second conductivity type, the highly-concentrated impurity region having a contact portion connected to the source electrode at a surface of the semiconductor layer, the highly-concentrated impurity region passing through the source region and extending to a position deeper than the source region, the highly-concentrated impurity region having a concentration higher than the impurity region.

1 - 22 . (canceled) 
     
     
         23 . A semiconductor device comprising:
 a semiconductor layer made of SiC;   a gate trench that defines a source region of a first conductivity type in the semiconductor layer;   a channel region of a second conductivity type formed under the source region;   a source trench that passes through the source region and the channel region;   an impurity region of the second conductivity type formed at a bottom part of the source trench; and   a conductive member filled in the source trench, wherein   the source region is continuously formed between the gate trench and the source trench.   
     
     
         24 . The semiconductor device according to  claim 23 , wherein the source trench has the same depth as the gate trench. 
     
     
         25 . The semiconductor device according to  claim 24 , further comprising a polysilicon material filled in the gate trench. 
     
     
         26 . The semiconductor device according to  claim 25 , wherein the channel region is formed up to an intermediate part in a thickness direction of the gate trench. 
     
     
         27 . The semiconductor device according to  claim 26 , further comprising an interlayer insulating film formed on an upper portion of the polysilicon material in the gate trench. 
     
     
         28 . The semiconductor device according to  claim 27 , further comprising an oxide film formed between the polysilicon material and an inner surface of the gate trench. 
     
     
         29 . The semiconductor device according to  claim 28 , wherein the oxide film has a curved portion formed at an upper portion of the gate trench. 
     
     
         30 . The semiconductor device according to  claim 29 , further comprising a source electrode formed on the semiconductor layer and electrically connected to the source region. 
     
     
         31 . The semiconductor device according to  claim 30 , wherein the source trench is formed as a single source trench in a cutting plane that appears when the semiconductor layer is cut in a direction of a depth of the source trench. 
     
     
         32 . The semiconductor device according to  claim 30 , wherein the source trench is formed as two source trenches in a cutting plane that appears when the semiconductor layer is cut in a direction of a depth of the source trench. 
     
     
         33 . The semiconductor device according to  claim 32 , wherein
 the gate trench is formed in a grid-shaped manner, and   the source trench is formed in a quadrangular shape or a quadrangular ring shape in a plan view in an inner region of the gate trench formed in the grid-shaped manner.   
     
     
         34 . The semiconductor device according to  claim 33 , wherein a repeated pattern of a line-and-space shape is formed by the gate trench and the source trench. 
     
     
         35 . The semiconductor device according to  claim 34 , wherein a repeated pattern of a hexagon is formed by the gate trench. 
     
     
         36 . The semiconductor device according to  claim 23 , further comprising:
 a highly-concentrated impurity region of the second conductivity type, the highly-concentrated impurity region having a contact portion formed at a part of the bottom part of the source trench, the highly-concentrated impurity region having a concentration higher than the impurity region; and   an electrode-film residue disposed at a peripheral part of the bottom part of the source trench.   
     
     
         37 . The semiconductor device according to  claim 36 , wherein the electrode-film residue is formed so as to selectively cover a peripheral edge part of the contact portion. 
     
     
         38 . The semiconductor device according to  claim 23 , further comprising:
 a highly-concentrated impurity region of the second conductivity type, the highly-concentrated impurity region having a contact portion formed at at-least one part of a peripheral part of the source trench, the highly-concentrated impurity region having a concentration higher than the impurity region; and   an electrode-film residue disposed in the source trench.   
     
     
         39 . The semiconductor device according to  claim 38 , further comprising a convex portion formed in an inner region of the source trench formed in a ring shape,
 wherein the contact portion is formed at a surface part of the convex portion.   
     
     
         40 . The semiconductor device according to  claim 38 , further comprising a convex portion formed between the source trench and the source trench both of which are adjacent to each other and each of which is formed in a stripe manner,
 wherein the contact portion is formed at a surface part of the convex portion.   
     
     
         41 . The semiconductor device according to  claim 38 , wherein the electrode-film residue is embedded in the source trench. 
     
     
         42 . The semiconductor device according to  claim 23 , wherein the source trench has a width greater than a width of the gate trench.