Semiconductor device having variably laterally doped zone with decreasing concentration formed in the termination region

Abstract

In a semiconductor body, a semiconductor device has an active region with a vertical drift section of a first conduction type and a near-surface lateral well of a second, complementary conduction type. An edge region surrounding this active region comprises a variably laterally doped doping material zone (VLD zone). This VLD zone likewise has the second, complementary conduction type and adjoins the well. The concentration of doping material of the VLD zone decreases to the concentration of doping material of the drift section along the VLD zone towards a semiconductor chip edge. Between the lateral well and the VLD zone, a transitional region is provided which contains at least one zone of complementary doping located at a vertically lower point than the well in the semiconductor body.

What is claimed is: 
     
         1 . A semiconductor device with a semiconductor body, comprising:
 an active region with a vertical drift section of a first conduction type and with a near-surface lateral well of a second, complementary conduction type;   an edge region surrounding the active region with a variably laterally doped doping material zone (VLD zone) of the second conduction type, which adjoins the lateral well and the concentration of doping material of which decreases to the concentration of doping material of the drift section along the VLD zone towards a semiconductor chip edge;   wherein at least one zone of complementary doping, which is located in the semiconductor body at a vertically lower point than the lateral well, is provided in a transitional region from the lateral well to the VLD zone; and   wherein the zone of complementary doping includes three floating zones of complementary doping arranged adjacent to one another below the transitional region, the distance between two of the adjacent zones increasing in the lateral direction from the active region towards the edge region.   
     
     
         2 . A semiconductor device with a semiconductor body, comprising:
 an active region with a vertical drift section of a first conduction type and with a near-surface lateral well of a second, complementary conduction type;   an edge region surrounding the active region with a variably laterally doped doping material zone (VLD zone) of the second conduction type, which adjoins the lateral well and the concentration of doping material of which decreases to the concentration of doping material of the drift section along the VLD zone towards a semiconductor chip edge; and   wherein at least one floating zone of complementary doping is provided in the semiconductor body below a transitional region from the lateral well to the VLD zone and where the at least one floating zone of complementary doping contacts neither the lateral well nor the VLD zone.   
     
     
         3 . The semiconductor device of  claim 2 , wherein the floating zone of complementary doping has a doping material dose D T  below the transitional region which is less than the breakthrough charge D S  of the surrounding semiconductor body, lying in the range of 0.005 D S ≦D T ≦0.8 D S . 
     
     
         4 . The semiconductor device of  claim 2 , wherein the floating zone of complementary doping has a vertical depth l v  related to the vertical length l D  of the drift section which lies in a range of 0.05≦l v /l D ≦0.95. 
     
     
         5 . The semiconductor device of  claim 2 , wherein the ratio of the lateral width b T  of the floating zone of the complementary doping and the vertical length l D  of the drift section lies in the range of 0.05≦b T /l D ≦0.2. 
     
     
         6 . The semiconductor device of  claim 2 , wherein the edge region is covered by a semi-insulating passivation layer comprising a diamond-like carbon layer (DLC layer) or an amorphous hydrogenated silicon carbide layer. 
     
     
         7 . The semiconductor device of  claim 2 , wherein at least two floating zones of complementary doping are provided adjacent to one another below the transitional region. 
     
     
         8 . The semiconductor device of  claim 2 , wherein at least two floating zones of complementary doping are provided below one another below the transitional region. 
     
     
         9 . The semiconductor device of  claim 2 , wherein at least three floating zones of complementary doping are provided adjacent to one another below the transitional region and the distance between two adjacent zones increases in the lateral direction from the active region towards the edge region. 
     
     
         10 . The semiconductor device of  claim 2 , wherein at least three floating zones of complementary doping are provided below one another below the transitional region and the distance between two adjacent zones increases in the vertical direction from the front side of the semiconductor body towards a side opposite the front side. 
     
     
         11 . The semiconductor device of  claim 2 , wherein at least two first floating zones of complementary doping are provided adjacent to one another below the transitional region and at least one third floating zone of complementary doping is provided below the first zones. 
     
     
         12 . The semiconductor device of  claim 2 , wherein the semiconductor device is a high-voltage power semiconductor device comprising a diode structure without compensation zones or a MOSFET structure with vertical compensation zones in the active region. 
     
     
         13 . A method for the production of a semiconductor device with a semiconductor body comprising an active region and an edge region, the method comprising:
 providing a semiconductor wafer of a first conduction type;   applying a photoresist mask covering the edge region while leaving the active region exposed for the introduction of a lateral well of a complementary conduction type into the semiconductor body in a transitional region towards the edge region, wherein the photoresist mask is provided with hole structures for a variably laterally doped doping material zone (VLD zone), which are arranged more densely towards the active region than towards a semiconductor chip edge;   ion implantation of a second conduction type complementary to the first conduction type into the semiconductor surface accompanied by the formation of islands of doping material below the hole structures of the photoresist mask;   exposing a transitional region between the lateral well and the VLD zone;   ion implantation of a doping material of the second conduction type into the transitional region with a higher ion beam energy than in the formation of the lateral well; and   diffusing the introduced complementary doping material to a lateral well of a complementary conduction type in the active region, a VLD zone in the edge region and a zone of complementary doping in the transitional region between the lateral well and the VLD zone, where the zone of complementary doping extends vertically more deeply into the semiconductor body than the lateral well.   
     
     
         14 . The method of  claim 13 , wherein the zone of complementary doping is produced in the transitional region between the lateral well and the VLD zone by using aluminium implantation followed by aluminium diffusion. 
     
     
         15 . The method of  claim 13 , wherein at least one low-lying floating zone of complementary doping is introduced below the transitional region between the lateral well and the VLD zone by using local doping of an individual low-lying epitaxial layer of a multi-epitaxial technology for semiconductor devices with compensation zones before the transition between the lateral well of complementary doping and the VLD zone is produced.