Semiconductor device with structure for improving breakdown voltage

Abstract

A semiconductor layer ( 10 ) provided on a BOX (buried oxide) layer ( 2 ) includes a first P-type region ( 11 ), an N + -type region ( 12 ), and an N − -type region ( 13 ) which together form a diode. A plurality of second P-type regions ( 14 ) are provided on a bottom part of the semiconductor layer ( 10 ). A plurality of insulating oxide films ( 21 ) are interposed between the plurality of second P-type regions ( 14 ). When the diode is in a reverse-biased state, the second P-type region ( 14 ) directly below the N + -type region ( 12 ) is approximately the same in potential as the N + -type region ( 12 ). The second P-type region ( 14 ) will be lower in potential relative to this second P-type region ( 14 ) directly below the N + -type region ( 12 ), as the second P-type region ( 14 ) gets nearer to the first P-type region ( 11 ). Electric field concentration can thus be relaxed at an interface between the semiconductor layer ( 10 ) and the BOX layer ( 2 ), whereby improvement in breakdown voltage of the diode is realized.

1 - 3 . (canceled)  
     
     
         4 . A semiconductor device, comprising: 
 a semiconductor substrate;    a first insulating film provided on said semiconductor substrate;    a first semiconductor layer provided on said first insulating film, said first semiconductor layer including a first region of a first conductivity type, a second region of a second conductivity type having a relatively low resistance, and a third region of said second conductivity type having a relatively high resistance, said third region being defined between said first region and said second region;    a plurality of conductive films provided at least on one side of said first insulating film; and    a third insulating film for isolating said plurality of conductive films from each other, and isolating said plurality of conductive films from said semiconductor substrate and/or from said first semiconductor layer.    
     
     
         5 . The semiconductor device according to  claim 4 , wherein 
 a predetermined potential can be applied from outside to each one of said plurality of conductive films.    
     
     
         6 . The semiconductor device according to  claim 4 , wherein 
 said plurality of conductive films are provided at least directly below said second region.    
     
     
         7 . The semiconductor device according to  claim 4 , wherein 
 said second region extends from an upper surface to a bottom surface of said first semiconductor layer.    
     
     
         8 . A semiconductor device, comprising: 
 a semiconductor substrate;    a first insulating film provided on said semiconductor substrate;    a first semiconductor layer provided on said first insulating film, said first semiconductor layer including a first region of a first conductivity type, a second region of a second conductivity type having a relatively low resistance, and a third region of said second conductivity type having a relatively high resistance, said third region being defined between said first region and said second region; and    a plurality of conductive films provided in said first insulating film, said plurality of conductive films being isolated from each other, wherein    a predetermined potential can be applied from outside to each one of said plurality of conductive films.    
     
     
         9 . The semiconductor device according to  claim 8 , wherein 
 said plurality of conductive films are provided at least directly below said second region.    
     
     
         10 . The semiconductor device according to  claim 8 , wherein 
 said second region extends from an upper surface to a bottom surface of said first semiconductor layer.    
     
     
         11 . A semiconductor device, comprising: 
 a semiconductor substrate;    a first insulating film provided on said semiconductor substrate;    a first semiconductor layer provided on said first insulating film, said first semiconductor layer including a first region of a first conductivity type, a second region of a second conductivity type having a relatively low resistance, and a third region of said second conductivity type having a relatively high resistance, said third region being defined between said first region and said second region;    a fourth insulating film provided on a side surface of said first semiconductor layer; and    a voltage dividing element provided along said first semiconductor layer while holding said fourth insulating film therebetween, said voltage dividing element dividing a voltage across said first region and said second region in a multistep process.    
     
     
         12 . A semiconductor device, comprising: 
 a semiconductor substrate;    a first insulating film provided on said semiconductor substrate;    a first semiconductor layer provided on said first insulating film, said first semiconductor layer including a first region of a first conductivity type, a second region of a second conductivity type having a relatively low resistance, and a third region of said second conductivity type having a relatively high resistance, said third region being defined between said first region and said second region;    a plurality of fifth regions of said first conductivity type provided in said first semiconductor layer with a certain distance therebetween, said plurality of fifth regions reaching a bottom surface of said first semiconductor layer; and    a plurality of fifth insulating films standing upright on said first insulating film with a certain distance therebetween, said plurality of fifth insulating films being provided to respective ones of said plurality of fifth regions, at least closer to said first region than said plurality of fifth regions.    
     
     
         13 . A semiconductor device, comprising: 
 a semiconductor substrate;    a first insulating film provided on said semiconductor substrate;    a first semiconductor layer provided on said first insulating film, said first semiconductor layer including a first region of a first conductivity type, a second region of a second conductivity type having a relatively low resistance, and a third region of said second conductivity type having a relatively high resistance, said third region being defined between said first region and said second region;    a sixth insulating film provided on a bottom part of said first semiconductor layer, said sixth insulating film standing upright on said first insulating film;    an electrode connected to said second region; and    a sixth region provided in said fist semiconductor layer to be connected to said electrode.