Nitride semiconductor device and manufacturing method thereof

Abstract

Provided are a nitride semiconductor device and a manufacturing method thereof. The nitride semiconductor device includes an insulating layer and a metal layer formed on a nitride semiconductor layer. The insulating layer makes contact with the nitride semiconductor layer. A separation preventing layer is formed between the insulating layer and the metal layer so as to make contact with each of these layers. The separation preventing layer has, as a main component, at least one kind of oxide of a metal selected from the group consisting of tungsten, molybdenum, chromium, titanium, nickel, hafnium, zinc, indium and yttrium.

1 . A method of manufacturing a nitride semiconductor device, comprising:
 forming a projecting structure of a nitride semiconductor layer, the projecting structure having a projecting portion and a lower surface, the projecting portion having an upper surface and side surfaces, the lower surface of the projecting structure adjacent to and extending from said side surfaces of said projecting portion, a first electrode layer being in contact with said upper surface of said projecting portion;   forming an insulating layer with an opening exposing said first electrode layer, the insulating layer contacting said side surfaces of said projecting portion and said lower surface of said projecting structure;   forming a separation preventing layer so as to be in contact with said insulating layer; and   forming a second electrode layer on said separation preventing layer and on said projecting structure, the second electrode layer contacting said separation preventing layer.   
     
     
         2 . The method of manufacturing a nitride semiconductor device according to  claim 1 , wherein said separation preventing layer is formed with an opening exposing said first electrode layer, and said second electrode layer is formed to be in contact with said first electrode layer and said separation preventing layer. 
     
     
         3 . The method of manufacturing a nitride semiconductor device according to  claim 1 , wherein said first electrode layer is formed to be in contact with said nitride semiconductor layer before forming said projecting structure. 
     
     
         4 . The method of manufacturing a nitride semiconductor device according to  claim 1 , wherein said separation preventing layer has, as a main component, at least one kind of oxide of a metal selected from the group consisting of tungsten, molybdenum, chromium, titanium, nickel, hafnium, zinc, indium, and yttrium. 
     
     
         5 . The method of manufacturing a nitride semiconductor device according to  claim 1 , wherein said insulating layer is made of silicon oxide, aluminum oxide, zirconium oxide, tantalum oxide, magnesium oxide, calcium fluoride, or magnesium. fluoride. 
     
     
         6 . The method of manufacturing a nitride semiconductor device according to  claim 1 , wherein said insulating layer is made of silicon oxide and said separation preventing layer is made of titanium oxide. 
     
     
         7 . The method of manufacturing a nitride semiconductor device according to  claim 1 , wherein said second electrode layer being in contact with said separation preventing layer includes a layer having, as a main component, at least one kind of metal selected from the group consisting of molybdenum, zirconium, hafnium, titanium, aluminum, tantalum, and vanadium. 
     
     
         8 . The method of manufacturing a nitride semiconductor device according to  claim 1 , wherein said first electrode layer includes, as a main component, palladium. 
     
     
         9 . The method of manufacturing a nitride semiconductor device according to  claim 1 , further comprising:
 first heat treating said second electrode layer at a temperature ranging from 150° C. to 300° C.; and   second heat treating said second electrode layer at a temperature ranging from 400° C. to 600° C. after said first heat treating.