Integrated circuits having source/drain structure and method of making

Abstract

A method includes selectively etching a region of a substrate using a germanium-containing gas, wherein the region of the substrate consists of Si and another material, and the other material consists of SiGe. The method further includes wherein the region has a laminated structure having a SiGe film over a Si film.

What is claimed is: 
     
         1 . A method comprising:
 selectively etching a region of a substrate using a germanium-containing gas, wherein the region of the substrate consists of Si and another material, and the other material consists of SiGe;   wherein the region has a laminated structure having a SiGe film over a Si film.   
     
     
         2 . The method of  claim 1 , further comprising:
 depositing a silicon layer; and   depositing a silicon germanium layer over the silicon layer, wherein the silicon layer and the silicon germanium layer define the region.   
     
     
         3 . The method of  claim 2 , wherein depositing the silicon layer comprises epitaxially growing the silicon layer. 
     
     
         4 . The method of  claim 2 , wherein depositing the silicon germanium layer comprises epitaxially growing the silicon germanium layer. 
     
     
         5 . The method of  claim 1 , wherein the germanium-containing gas comprises germanium hydride. 
     
     
         6 . The method of  claim 1 , wherein selectively etching the region comprises selectively etching the region at a temperature of 750° C. or less. 
     
     
         7 . The method of  claim 1 , wherein selectively etching the region comprises selectively etching the region at a pressure ranging from about 50 Torr to about 500 Torr. 
     
     
         8 . A method comprising:
 depositing a silicon germanium film over a silicon film, wherein the silicon germanium layer and the silicon layer define a region;   selectively etching the region using a germanium-containing gas;   wherein the region has a laminated structure having a SiGe film over a Si film.   
     
     
         9 . The method of  claim 8 , further comprising:
 depositing the silicon film.   
     
     
         10 . The method of  claim 9 , wherein depositing the silicon film comprises epitaxially growing the silicon film. 
     
     
         11 . The method of  claim 8 , wherein depositing the silicon germanium film comprises epitaxially growing the silicon germanium film. 
     
     
         12 . The method of  claim 8 , wherein the germanium-containing gas comprises germanium hydride. 
     
     
         13 . The method of  claim 8 , wherein selectively etching the region comprises selectively etching the region at a temperature of 750° C. or less. 
     
     
         14 . The method of  claim 8 , wherein selectively etching the region comprises selectively etching the region at a pressure ranging from about 50 Torr to about 500 Torr. 
     
     
         15 . The method of  claim 8 , further comprising depositing a silicon-containing material over the silicon germanium film following the etching of the region. 
     
     
         16 . A method comprising:
 epitaxially growing a silicon germanium layer over a silicon layer to define a substrate;   selectively etching a region of the substrate using a germanium containing gas, wherein the silicon germanium layer and the silicon layer are laminated alternately.   
     
     
         17 . The method of  claim 16 , wherein the germanium-containing gas comprises germanium hydride. 
     
     
         18 . The method of  claim 16 , wherein selectively etching the region comprises selectively etching the region at a temperature of 750° C. or less. 
     
     
         19 . The method of  claim 16 , wherein selectively etching the region comprises selectively etching the region at a pressure ranging from about 50 Torr to about 500 Torr. 
     
     
         20 . The method of  claim 16 , further comprising depositing a silicon-containing layer over the silicon germanium layer.