Semiconductor device and method of manufacturing same

Abstract

A semiconductor device including an N-type semiconductor substrate which includes arsenic as an impurity, a first electrode formed on a main surface of the N-type semiconductor substrate, a ground surface formed on another surface of the N-type semiconductor substrate, a second electrode formed on the ground surface and ohmically-contacted with the N-type semiconductor substrate, a semiconductor element formed in the N-type semiconductor substrate and flowing current between the first electrode and the second electrode during ON-state thereof. The device has a reduced ON-resistance thereof.

1 . A method of manufacturing a vertical type semiconductor device comprising: 
 preparing a semiconductor wafer which has a heavily doped semiconductor substrate doped with arsenic as an impurity and a lightly doped semiconductor layer disposed over said semiconductor substrate;    forming a semiconductor element at a surface portion of said semiconductor layer;    forming a first metal layer for a first electrode of said semiconductor element over said surface portion of said semiconductor layer;    grinding a back of said semiconductor substrate to thin said semiconductor substrate and roughen a back surface of said semiconductor substrate, said grinding being performed until a thickness from a surface of said first metal layer to said back surface is 200-450 microns;    performing a RF etching upon said back surface; and    forming on said back surface a second metal layer for a second electrode of said semiconductor element.    
   
   
       2 . A method of manufacturing a vertical type semiconductor device according to  claim 1 , wherein said forming of said second metal layer includes forming by a sputtering method.  
   
   
       3 . A method of manufacturing a vertical type semiconductor device comprising: 
 preparing a semiconductor wafer which has a heavily doped semiconductor substrate and a lightly doped semiconductor layer disposed over said semiconductor substrate;    forming a semiconductor element at a surface portion of said semiconductor layer;    forming a first metal layer for a first electrode of said semiconductor element over said surface portion of said semiconductor layer;    grinding a back of said semiconductor substrate to thin said semiconductor substrate and roughen a back surface of said semiconductor substrate;    performing a RF etching upon said back surface; and    forming on said back surface a second metal layer for a second electrode of said semiconductor element.    
   
   
       4 . A method of manufacturing a vertical type semiconductor device according to  claim 3 , wherein said forming of said second metal layer includes forming by a sputtering method.