Semiconductor fabrication and structure for field-effect and bipolar transistor devices

Abstract

Semiconductor devices have device regions in which semiconductor properties such as spreading resistivity and its profile are significant. In making a p-type device region on a semiconductor wafer, an initial semiconductor device region is defined by a buried region, and an initial spreading resistivity profile is developed by annealing. After annealing, semiconductor device properties can be enhanced by removing a surface sub-region of the initial device region, and can be further improved by epitaxially growing thereon a monocrystalline film as an improved channel layer for FET devices. Such properties are relevant in MOS as well as bipolar devices.

1 . A semiconductor device comprising a p-type device region on at least a portion of a surface of a semiconductor substrate having an original bulk resistivity, said device region having a spreading resistivity profile that increases from a surface region to a peak value at a depth below said surface region, and said spreading resistivity value in said device region being greater than said original bulk resistivity of said wafer.  
   
   
       2 . A semiconductor device comprising a composite device region on at least a portion of a surface of a semiconductor substrate having an original bulk resistivity, said composite device region comprising an epitaxial layer grown on the surface of a recrystallized p-type layer, and said p-type layer having a spreading resistivity profile that increases from the surface region to a peak value at a depth below the surface region.  
   
   
       3 . The device of  claim 2 , wherein said peak value is greater than said original bulk resistivity.  
   
   
       4 . The device of  claim 2 , wherein said epitaxial layer is n-type.  
   
   
       5 . The device of  claim 4 , wherein said substrate is p-type.  
   
   
       6 . The device of  claim 4 , wherein said substrate is p-type.  
   
   
       7 . The device of  claim 2 , wherein said epitaxial layer is p-type.  
   
   
       8 . The device of  claim 7 , wherein said substrate is p-type.  
   
   
       9 . The device of  claim 7 , wherein said substrate is n-type.