Method and system for in-situ etch and regrowth in gallium nitride based devices

Abstract

A method of regrowing material includes providing a III-nitride structure including a masking layer and patterning the masking layer to form an etch mask. The method also includes removing, using an in-situ etch, a portion of the III-nitride structure to expose a regrowth region and regrowing a III-nitride material in the regrowth region.

What is claimed is: 
     
         1 . A method of regrowing material, the method comprising:
 providing a III-nitride structure including a masking layer;   patterning the masking layer to form an etch mask;   removing, using an in-situ etch, a portion of the III-nitride structure to expose a regrowth region; and   regrowing a III-nitride material in the regrowth region.   
     
     
         2 . The method of  claim 1  wherein the III-nitride structure comprises:
 a substrate characterized by a first conductivity type; 
 a first epitaxial layer coupled to the substrate and characterized by the first conductivity type; and 
 a second epitaxial layer coupled to the first epitaxial layer and characterized by a second conductivity type, wherein the masking layer is coupled to the second epitaxial layer. 
 
     
     
         3 . The method of  claim 2  wherein removing a portion of the III-nitride structure comprises removing a portion of the second epitaxial layer and a portion of the first epitaxial layer, wherein the regrowth region is disposed in the first epitaxial layer. 
     
     
         4 . The method of  claim 3  wherein regrowing the III-nitride material is performed in a growth reactor and removing a portion of the second epitaxial layer and a portion of the first epitaxial layer is an in-situ process performed in the growth reactor. 
     
     
         5 . The method of  claim 2  further comprising:
 removing a portion of the regrown III-nitride material to expose the second epitaxial layer; 
 forming a first electrical contact to portions of the first epitaxial layer and portions of the second epitaxial layer; and 
 forming a second electrical contact to the substrate. 
 
     
     
         6 . The method of  claim 5  wherein the first electrical contact comprises:
 a Schottky contact to the portions of the first epitaxial layer; and 
 an ohmic contact to the portions of the second epitaxial layer. 
 
     
     
         7 . The method of  claim 2  wherein the first epitaxial layer comprises an n-doped III-nitride material. 
     
     
         8 . The method of  claim 7  wherein the III-nitride material comprises GaN. 
     
     
         9 . The method of  claim 2  wherein the second epitaxial layer comprises a III-nitride material. 
     
     
         10 . The method of  claim 9  wherein the III-nitride material comprises GaN. 
     
     
         11 . The method of  claim 1  wherein the masking layer comprises AlN. 
     
     
         12 . The method of  claim 11  wherein the AlN is characterized by a thickness less than 4 nm. 
     
     
         13 . A method of fabricating an MPS diode, the method comprising:
 providing a III-nitride structure including:
 a substrate characterized by a first conductivity type; 
 a first epitaxial layer coupled to the substrate and characterized by the first conductivity type; 
 a second epitaxial layer coupled to the first epitaxial layer and characterized by a second conductivity type; and 
 a masking layer coupled to the second epitaxial layer; 
   patterning the masking layer to form an etch mask;   placing the III-nitride structure in a growth chamber;   removing a portion of the second epitaxial layer and a portion of the first epitaxial layer to expose a regrowth region;   regrowing a III-nitride material in the regrowth region;   removing the regrown structure from the growth chamber;   removing a portion of the regrown III-nitride material to expose the second epitaxial layer;   forming a Schottky contact to the regrown III-nitride material;   forming an ohmic contact to portions of the second epitaxial layer; and   forming a second ohmic contact to the substrate.   
     
     
         14 . The method of  claim 13  wherein the regrowth region extends through the second epitaxial layer to the first epitaxial layer. 
     
     
         15 . The method of  claim 13  wherein the growth chamber comprises an MOCVD reactor. 
     
     
         16 . The method of  claim 13  wherein the first epitaxial layer comprises an n-type III-nitride material. 
     
     
         17 . The method of  claim 16  wherein the n-type III-nitride material comprises n− GaN. 
     
     
         18 . The method of  claim 13  wherein the second epitaxial layer comprises a III-nitride material. 
     
     
         19 . The method of  claim 18  wherein the III-nitride material comprises p+GaN. 
     
     
         20 . The method of  claim 13  wherein the masking layer comprises AN.