Semiconductor device and manufacturing method

Abstract

A semiconductor device includes: a first conductivity type semiconductor substrate made of silicon carbide; a second conductivity type body region in a device region of the semiconductor substrate; a first conductivity type source region formed in the body region; and a gate electrode formed on the body region through gate insulating films. The semiconductor device further includes, in a termination region of the semiconductor substrate, second conductivity type RESURF layers, and an edge termination region formed in the RESURF layers. Then, the RESURF layers and a front surface of the semiconductor substrate adjacent to the RESURF layers are covered by an oxidation-resistant insulating film.

1 . A semiconductor device comprising:
 a semiconductor substrate of a first conductivity type, the semiconductor substrate having a principal surface and a rear surface, being made of silicon carbide, and having, on the principal surface, a device region, a termination region surrounding a circumference of the device region, and a side positioned opposite the device region with respect to the termination region;   a first semiconductor region of a second conductivity type that is an opposite conductivity type to the first conductivity type, the first semiconductor region being formed in the semiconductor substrate in the device region;   a second semiconductor region formed inside the first semiconductor region and having the first conductivity type;   a gate electrode formed between the semiconductor substrate and the second semiconductor region and on the first semiconductor region through a gate insulating film;   an annular third semiconductor region formed in the semiconductor substrate in the termination region, having the second conductivity type, and surrounding the circumference of the device region in a plan view;   an annular fourth semiconductor region formed inside the third semiconductor region, having the second conductivity type, and surrounding the circumference of the device region in a plan view;   a first electrode formed over the principal surface of the semiconductor substrate, and connected to the first semiconductor region, the second semiconductor region, and the fourth semiconductor region; and   a second electrode formed on the rear surface of the semiconductor substrate,   wherein an impurity concentration of the third semiconductor region is lower than that of the fourth semiconductor region,   the semiconductor substrate comes in contact with the third semiconductor region in the principal surface, and includes an annular fifth semiconductor region surrounding a circumference of the third semiconductor region, and   the third semiconductor region and the fifth semiconductor region between the fourth semiconductor region and the side are covered with an oxidation-resistant insulating film formed on the principal surface.   
     
     
         2 . The semiconductor device according to  claim 1 ,
 wherein the oxidation-resistant insulating film is configured by a silicon nitride film or a silicon oxynitride film.   
     
     
         3 . The semiconductor device according to  claim 1 ,
 wherein the fourth semiconductor region includes a first region covered with the gate insulating film, and a second region covered with the oxidation-resistant insulating film.   
     
     
         4 . The semiconductor device according to  claim 3 ,
 wherein a front surface of the first region is nearer to the rear surface of the semiconductor substrate than a front surface of the second region.   
     
     
         5 . The semiconductor device according to  claim 1 ,
 wherein the third semiconductor region includes annular sixth and seventh semiconductor regions each surrounding the circumference of the device region in a plan view,   the sixth semiconductor region is positioned to be nearer to a side of the device region than the seventh semiconductor region, and   the sixth semiconductor region and the seventh semiconductor region each have the second conductivity type, and an impurity concentration of the seventh semiconductor region is lower than that of the sixth semiconductor region.   
     
     
         6 . The semiconductor device according to  claim 5 ,
 wherein the seventh semiconductor region includes a region overlapping with the sixth semiconductor region.   
     
     
         7 . The semiconductor device according to  claim 1 , further comprising a plurality of eighth semiconductor regions formed inside the third semiconductor region, surrounding the circumference of the device region, and each having an annular shape,
 wherein the plurality of eighth semiconductor regions are more remote from the device region than the fourth semiconductor region, and   the plurality of eighth semiconductor regions each have the second conductivity type, and an impurity concentration of each of the eighth semiconductor regions is higher than that of the third semiconductor region.   
     
     
         8 . The semiconductor device according to  claim 7 , further comprising a plurality of ninth semiconductor regions formed inside the fifth semiconductor region, surrounding the circumference of the device region, and each having an annular shape,
 wherein the plurality of ninth semiconductor regions each have the second conductivity type, and an impurity concentration of each of the ninth semiconductor regions is lower than that of the fourth semiconductor region.   
     
     
         9 - 20 . (canceled)