Electrode contact section of semiconductor device

Abstract

A p-type impurity layer is formed in an n-type semiconductor substrate. Since the p-type impurity layer has a low impurity concentration and a sufficiently shallow depth of 1.0 μm or less, the carrier injection coefficient can be reduced. In the p-type impurity layer, a p-type contact layer of a high impurity concentration is formed for reducing a contact resistance. Since the p-type contact layer has a sufficiently shallow depth of 0.2 μm or less, it does not influence the carrier injection coefficient. Further, a silicide layer is formed between the p-type contact layer and an electrode such that the contact-layer-side end of the silicide layer corresponds to that portion of the p-type contact layer, at which the concentration profile of the contact layer assumes a peak value. The silicide layer further reduces the contact resistance.

What is claimed is:  
     
         1 . An electrode contact section incorporated in a semiconductor device, comprising: 
 a first-conductivity-type semiconductor substrate;    a second-conductivity-type impurity layer formed in one surface of the semiconductor substrate and having a thickness of not more than 1.0 μm from a surface of the semiconductor substrate;    a second-conductivity-type contact layer formed in the impurity layer and having a thickness of not more than 0.2 μm from the surface of the semiconductor substrate, the contact layer being thinner than the impurity layer and having a higher impurity concentration than the impurity layer; and    a first electrode formed on the contact layer.    
     
     
         2 . The electrode contact section according to    claim 1   , wherein the impurity layer is provided for carrier injection from the impurity layer to the semiconductor substrate, and the contact layer is provided for reducing a contact resistance between the first electrode and the impurity layer and not for carrier injection.  
     
     
         3 . The electrode contact section according to    claim 1   , further comprising a second electrode formed at another surface side of the semiconductor substrate for allowing a current to flow between the first and second electrodes.  
     
     
         4 . The electrode contact section according to    claim 3   , wherein the semiconductor device is an IGBT.  
     
     
         5 . The electrode contact section according to    claim 1   , wherein the impurity layer is formed in the entire one surface of the semiconductor substrate.  
     
     
         6 . The electrode contact section according to    claim 1   , wherein the impurity layer is formed in a portion of the one surface of the semiconductor substrate.  
     
     
         7 . An electrode contact section incorporated in a semiconductor device, comprising: 
 a first-conductivity-type semiconductor substrate;    a second-conductivity-type impurity layer formed in one surface of the semiconductor substrate;    a second-conductivity-type contact layer formed in the impurity layer, being thinner than the impurity layer and having a higher impurity concentration than the impurity layer;    a first electrode formed on the contact layer; and    a silicide layer formed between the first electrode and the contact layer, the silicide layer having a contact-layer-side end thereof made to substantially correspond to that portion of the contact layer, at which a concentration profile of the contact layer assumes a peak value.    
     
     
         8 . The electrode contact section according to    claim 7   , wherein the impurity layer is provided for carrier injection from the impurity layer to the semiconductor substrate, and the contact layer is provided for reducing a contact resistance between the first electrode and the impurity layer and not for carrier injection.  
     
     
         9 . The electrode contact section according to    claim 7   , further comprising a second electrode formed at another surface side of the semiconductor substrate for allowing a current to flow between the first and second electrodes.  
     
     
         10 . The electrode contact section according to    claim 9   , wherein the semiconductor device is an IGBT.  
     
     
         11 . The electrode contact section according to    claim 7   , wherein the impurity layer has a thickness of not more than 1.0 μm from a surface of the semiconductor substrate.  
     
     
         12 . The electrode contact section according to    claim 7   , wherein the contact layer has a thickness of not more than 0.2 μm from a surface of the semiconductor substrate.  
     
     
         13 . The electrode contact section according to    claim 7   , wherein the silicide layer has a thickness of not more than 0.2 μm from a surface of the semiconductor substrate, and is thinner than the contact layer.  
     
     
         14 . The electrode contact section according to    claim 7   , wherein the impurity layer is formed in the entire one surface of the semiconductor substrate.  
     
     
         15 . The electrode contact section according to    claim 7   , wherein the impurity layer is formed in a portion of the one surface of the semiconductor substrate.