Semiconductor device

Abstract

A semiconductor device includes a first conductivity type semiconductor layer having a first surface and a second surface opposite to the first surface and having an element portion formed in the first surface and an outer peripheral portion surrounding the element portion, a semiconductor element structure formed in the element portion, multiple guard ring trenches formed in the outer peripheral portion and each formed in the first surface of the semiconductor layer, and a second conductivity type outer peripheral portion impurity region formed in the outer peripheral portion, in which the multiple guard ring trenches include a first unit consisting of multiple guard ring trenches and a second unit consisting of multiple guard ring trenches arranged on the outside of the semiconductor layer relative to the multiple guard ring trenches belonging to the first unit, and in which the outer peripheral portion impurity region includes a first portion arranged below the multiple guard ring trenches belonging to the first unit and having a first depth with respect to the first surface of the semiconductor layer and a second portion arranged below the multiple guard ring trenches belonging to the second unit and having a second depth smaller than the first depth with respect to the first surface of the semiconductor layer.

1 - 18 . (canceled) 
     
     
         19 . A semiconductor device, comprising:
 a first conductivity type semiconductor layer having a first surface and a second surface opposite to the first surface and having an element portion formed in the first surface and an outer peripheral portion surrounding the element portion;   a semiconductor element structure formed in the element portion;   guard ring recessed portions formed in the outer peripheral portion, and each formed in the first surface of the semiconductor layer; and   a second conductivity type outer peripheral portion impurity region formed in the outer peripheral portion, wherein   the guard ring recessed portions include a first unit consisting of guard ring recessed portions and a second unit consisting of guard ring recessed portions arranged on the outside of the semiconductor layer relative to guard ring recessed portions belonging to the first unit, and wherein   the outer peripheral portion impurity region includes a first portion arranged below the guard ring recessed portions belonging to the first unit and having a first depth with respect to the first surface of the semiconductor layer and a second portion arranged below the guard ring recessed portions belonging to the second unit and having a second depth smaller than the first depth with respect to the first surface of the semiconductor layer.   
     
     
         20 . The semiconductor device according to  claim 19 , wherein
 the outer peripheral portion impurity region further includes a base portion formed continuously between the first unit and the second unit, arranged in a region between adjacent ones of guard ring recessed portions and at the bottom of the adjacent ones of the guard ring recessed portions, and exposed to the first surface of the semiconductor layer, and wherein   the first portion and the second portion are connected integrally to the base portion below the guard ring recessed portions and each protrudes selectively from the base portion toward the second surface of the semiconductor layer.   
     
     
         21 . The semiconductor device according to  claim 19 , wherein
 the guard ring recessed portions further include a third unit consisting of guard ring recessed portions arranged on the outside of the semiconductor layer relative to the guard ring recessed portions belonging to the second unit, and wherein   the outer peripheral portion impurity region further includes a third portion arranged in a region between adjacent ones of the guard ring recessed portions in the third unit and having a depth at a middle portion in a depth direction of the guard ring recessed portions with respect to the first surface of the semiconductor layer.   
     
     
         22 . The semiconductor device according to  claim 21 , wherein
 the guard ring recessed portions further include a fourth unit consisting of guard ring recessed portions arranged on the outside of the semiconductor layer relative to the guard ring recessed portions belonging to the third unit, and wherein   a first conductivity type portion of the semiconductor layer is arranged in a region between adjacent ones of the guard ring recessed portions in the fourth unit over the entire depth direction of the guard ring recessed portions.   
     
     
         23 . The semiconductor device according to  claim 19 , wherein
 a pitch of the guard ring recessed portions belonging to the first unit is greater than a pitch of the guard ring recessed portions belonging to the second unit.   
     
     
         24 . The semiconductor device according to  claim 19 , wherein
 a pitch of the guard ring recessed portions belonging to the first unit is smaller than a pitch of the guard ring recessed portions belonging to the second unit.   
     
     
         25 . The semiconductor device according to  claim 19 , wherein
 a depth of the guard ring recessed portions is within a range of 0.8 μm to 3.0 μm,   the first depth is within a range of 0.8 μm to 3.0 μm, and   the second depth is within a range of 0.8 μm to 2.0 μm.   
     
     
         26 . The semiconductor device according to  claim 19 , further comprising:
 a first insulating film formed on an inner surface of the guard ring recessed portions; and   a conductive material embedded in the guard ring recessed portions with the first insulating film therebetween.   
     
     
         27 . The semiconductor device according to  claim 26 , wherein the first insulating film includes a silicon oxide film and the conductive material includes polysilicon. 
     
     
         28 . The semiconductor device according to  claim 26 , wherein the outer peripheral portion impurity region further includes a fourth portion formed on the outside of the semiconductor layer relative to an outermost one of the guard ring recessed portions and having a depth greater than that of the guard ring recessed portions with respect to the first surface of the semiconductor layer. 
     
     
         29 . The semiconductor device according to  claim 28 , wherein the fourth portion of the outer peripheral portion impurity region is electrically connected to the conductive material embedded in an outermost one of the guard ring recessed portions. 
     
     
         30 . The semiconductor device according to  claim 19 , wherein the semiconductor element structure includes:
 gate recessed portions formed in the first surface of the semiconductor layer;   a gate insulating film formed on an inner surface of gate recessed portions;   a gate electrode embedded in the gate recessed portions with the gate insulating film therebetween;   a second conductivity type channel region formed in a region between adjacent ones of gate recessed portions; and   a first conductivity type source region being in contact with the channel region, formed in the first surface of the semiconductor layer in a region between adjacent ones of gate recessed portions.   
     
     
         31 . The semiconductor device according to  claim 30 , further comprising a second conductivity type element portion impurity region formed below a region between adjacent ones of the gate recessed portions, wherein
 the element portion impurity region includes a first portion having a depth equal to the first depth with respect to the first surface of the semiconductor layer.   
     
     
         32 . The semiconductor device according to  claim 31 , wherein the element portion impurity region includes a second portion connected integrally to the channel region and protruding selectively from the channel region toward the second surface of the semiconductor layer. 
     
     
         33 . The semiconductor device according to  claim 32 , wherein the first portion of the element portion impurity region is separated from the second portion of the element portion impurity region in a direction from the first surface toward the second surface of the semiconductor layer. 
     
     
         34 . The semiconductor device according to  claim 30 , further comprising:
 a field recessed portion extending in a region between adjacent ones of gate recessed portions from the first surface of the semiconductor layer through the source region to the channel region; and   an embedded contact embedded in the field recessed portion and electrically connected to the source region and the channel region.   
     
     
         35 . The semiconductor device according to  claim 34 , further comprising:
 a second insulating film formed selectively on the inner surface of the field recessed portion and on an inner surface formed by the channel region; and   a field plate composed of a conductive material embedded in the field recessed portion with the second insulating film therebetween.   
     
     
         36 . The semiconductor device according to  claim 35 , wherein the field plate is electrically connected to the embedded contact.