Epitaxially coated semiconductor wafer

Abstract

A process for epitaxially coating the front surface of a semiconductor wafer in a CVD reactor, the front surface of the semiconductor wafer being exposed to a process gas which contains a source gas and a carrier gas, and the back surface of the semiconductor wafer being exposed to a displacement gas, wherein the displacement gas contains no more than 5% by volume of hydrogen, with the result that diffusion of dopants out of the back surface of the semiconductor wafer, which is intensified by hydrogen, is substantially avoided. With this process, it is possible to produce a semiconductor wafer with a substrate resistivity of ≦100 mΩcm and a resistivity of the epitaxial layer of >1 Ωcm without back-surface coating, the epitaxial layer of which semiconductor wafer has a resistance inhomogeneity of <10%.

1 . A semiconductor wafer having a substrate resistivity of ≦100 mΩcm and having a resistivity of an epitaxial layer of >1 Ωcm, which does not have a back-surface coating, the epitaxial layer has a resistance inhomogeneity of <10%.  
   
   
       2 . The semiconductor wafer as claimed in  claim 1 , 
 wherein resistance on a wafer back surface following an epitaxial coating deviates by at most 15% from a resistance of the wafer back surface before the epitaxial coating.    
   
   
       3 . A susceptor for a CVD reactor, comprising 
 a substantially planar surface, an elevated edge region on which a substrate which is to be treated in the CVD reactor rests; and    at least one device for mechanically manipulating the substrate, wherein the device for mechanically manipulating the substrate has at least one opening, through which a gas can be supplied to a back surface of the substrate.    
   
   
       4 . The susceptor as claimed in  claim 3 , 
 wherein the device for mechanically manipulating the substrate is a central axis for rotating the susceptor and the substrate.    
   
   
       5 . The susceptor as claimed in  claim 3 , 
 wherein the device for mechanically manipulating the substrate is a lift mechanism for lifting the substrate off the susceptor.