Junction termination for SiC schottky diode

Abstract

A semiconductor diode structure comprising a Schottky junction, where a metal contact and a silicon carbide semiconducting layer of a first conducting type form said junction and where the edge of the junction exhibits a Junction Termination Extension (JTE) laterally surrounding the junction, said JTE having a charge profile with a stepwise or uniformly decreasing total charge or effective sheet charge density from an initial value to a zero or almost zero total charge at the outermost edge of the termination following a radial direction from the centre part of the JTE towards the outermost edge of the termination. The object of the junction termination extension is to control the electric field at the periphery of the diode.

1 . A semiconductor device comprising a first conducting type layer ( 9 ) and a metal contact layer ( 2 ) forming a Schottky junction, where the first conducting type layer is made of silicon carbide (SiC), characterized in that said first conducting type layer ( 9 ) is immersed into a second lower doped first conducting type layer ( 7 ), whereby said junction is provided with a Junction Termination Extension (JTE).  
     
     
         2 . A semiconductor device according to  claim 1 , characterized in that the first conducting type layer ( 9 ) of the Schottky junction is formed as a trench ( 8 ) in the second layer ( 7 ) of the first conducting type.  
     
     
         3 . A semiconductor device according to  claim 1 , characterized in that the first conducting type layer ( 9 ) is formed as a region established by ion implantation into the second layer ( 7 ) of the first conducting type.  
     
     
         4 . A semiconductor device according to  claim 1 , characterized in that said second layer ( 7 ) of the first conducting type is a top layer of a highly doped substrate of the first conducting type.  
     
     
         5 . A semiconductor device according to  claim 1 , characterized in that the first conducting type layer of the Schottky junction is formed as a MESA ( 10 ) on top of a higher doped layer ( 6 ) of the first conducting type.  
     
     
         6 . A semiconductor device according to  claim 5 , characterized in that a lower doped second layer ( 11 ) of the first conducting type surrounds the MESA formed first conducting type Schottky junction layer ( 10 ).  
     
     
         7 . A semiconductor device according to  claim 6 , characterized in that the metal contact ( 8 ) is applied to the MESA formed first conducting type Schottky junction layer ( 10 ) through an aperture in the second layer ( 11 ) of the first conducting type.  
     
     
         8 . Method of manufacturing a semiconductor component comprising a first conducting type layer ( 9 ) and a metal contact layer ( 2 ) forming a Schottky junction, where the first conducting type layer is made of silicon carbide (SiC), the edge of the Schottky junction to be provided with a termination extension, comprising the steps of: 
 etching a trench ( 8 ) at a surface of a silicon carbide wafer ( 6 ,  7 ) having a lower doped layer ( 7 ) of the first conducting type SiC material at said surface,    epitaxially growing an n-base region ( 9 ) in said trench ( 8 ) with a first conducting type material being of higher doping concentration than said lower doped layer ( 7 ),    applying a metal contact layer to the surface of said n-base region ( 9 ) for forming said metal Schottky contact ( 2 ).    
     
     
         9 . Method of manufacturing a semiconductor component comprising a first conducting type layer ( 9 ) and a metal contact layer ( 2 ) forming a Schottky junction, where the first conducting type layer is made of silicon carbide (SiC), the edge of the Schottky junction to be provided with a termination extension, comprising the steps of: 
 implanting ions into a region of a surface of a silicon carbide wafer ( 6 ,  7 ) having a lower doped layer ( 7 ) of the first conducting type SiC material at said surface for    creating an n-base region ( 9 ) having a first conducting type material being of higher doping concentration than said lower doped layer ( 7 ),    applying a metal contact layer on the surface of said n-base region ( 9 ) for forming said metal Schottky contact ( 2 ).    
     
     
         10 . Method of manufacturing a semiconductor component comprising a first conducting type layer ( 10 ) and a metal contact layer ( 2 ) forming a Schottky junction, where the first conducting type layer is made of silicon carbide (SiC), the edge of the Schottky junction to be provided with a termination extension, comprising the steps of: 
 epitaxially growing on a surface of a highly doped first conducting type silicon carbide wafer ( 6 ) a first SiC layer of the first conductive type having a doping concentration lower than the doping concentration of said wafer ( 6 ),    etching said first layer for forming an n-base region ( 10 ) as a MESA structure of the remainder of said first layer, epitaxially growing an edge layer ( 11 ) of the first conductive type SiC material having a lower doping concentration than said n-base region ( 10 ) around said n-base region,    etching a window in said edge layer ( 11 ) down to said n-base region ( 10 ), and    applying a metal contact layer on the surface of said n-base region ( 9 ) for forming said metal Schottky contact ( 2 ).    
     
     
         11 . Method according to  claim 8  or  9 , characterized in that the implant used to form the n-base surrounding layer ( 9 ) of n-conducting type material is nitrogen.