Semiconductor device and method for manufacturing the same

Abstract

A semiconductor device includes: an N-type drift layer; a P-type anode layer on the N-type drift layer; a trench penetrating the P-type anode layer; a conductive substance embedded in the trench via an insulating film; and an N-type buffer layer between the N-type drift layer and the P-type anode layer and having impurity concentration which is higher than that of the N-type drift layer.

1 . A semiconductor device comprising:
 an N-type drift layer;   a P-type anode layer on the N-type drift layer;   a trench penetrating the P-type anode layer;   a conductive substance embedded in the trench via an insulating film; and   an N-type buffer layer between the N-type drift layer and the P-type anode layer and having impurity concentration which is higher than that of the N-type drift layer.   
     
     
         2 . The semiconductor device according to  claim 1 , wherein the trench has a width which is equal to or below 1.2 μm. 
     
     
         3 . The semiconductor device according to  claim 1 , wherein the N-type buffer layer has an impurity concentration which is equal to or below 1×10 17  cm −3 . 
     
     
         4 . A method for manufacturing a semiconductor device comprising:
 forming a P-type anode layer on a top surface of an N-type drift layer;   selectively forming an N-type cathode layer in a first region of an underside of the N-type drift layer; and   selectively forming a P-type cathode layer in a second region which is different from the first region of the underside of the N-type drift layer.   
     
     
         5 . A semiconductor device comprising
 an N-type drift layer;   a P-type anode layer on a part of the N-type drift layer;   an anode electrode connected to the P-type anode layer; and   an insulating film between an outer end of the P-type anode layer and the anode electrode,   wherein a length between the outer end of the P-type anode layer and an inner end of the insulating film is 100 μm or above.