SiGe FINS FORMED ON A SUBSTRATE

Abstract

A method includes selectively forming a silicon-germanium (SiGe) layer on a substrate. At least one SiGe fin with a first width is formed from the SiGe layer. At least one Si fin with a second width is formed from an upper portion of the substrate. The at least one SiGe fin with the first width, the at least one Si fin with the second width and a surface of the substrate below the at least one Si fin are oxidized. The first width of the at least one SiGe fin is condensed in width to a target width.

What is claimed is: 
     
         1 . A method, comprising:
 selectively forming a silicon-germanium (SiGe) layer on a substrate;   forming at least one SiGe fin with a first width from the SiGe layer;   forming at least one Si fin with a second width from an upper portion of the substrate; and   oxidizing the at least one SiGe fin with the first width, the at least one Si fin with the second width and a surface of the substrate below the at least one Si fin, wherein the first width of the at least one SiGe fin is condensed in width to a target width.   
     
     
         2 . The method of  claim 1 , wherein the at least one Si fin is completely oxidized forming an oxide layer between the at least one SiGe fin and the substrate. 
     
     
         3 . The method of  claim 2 , wherein the oxidizing results in a higher percentage of Ge in the at least one SiGe fin with the target width than a percentage of Ge in the SiGe layer, the target width is less than the second width, and the second width is less than the first width. 
     
     
         4 . The method of  claim 3 , further comprising:
 selectively removing the oxide layer from side surfaces of the at least one SiGe fin.   
     
     
         5 . The method of  claim 4 , further comprising:
 depositing a nitride liner on a surface of a remaining portion of the oxide layer; and   depositing a flowable oxide layer on the nitride layer,   wherein forming the SiGe layer comprises epitaxially growing the SiGe layer on a top surface of the substrate.   
     
     
         6 . The method of  claim 4 , wherein forming the at least one SiGe fin with a first width comprises:
 forming a masking layer on a top surface of the SiGe layer; and   etching the at least one SiGe fin with the first width.   
     
     
         7 . The method of  claim 6 , further comprising forming a spacer layer on the at least one SiGe fin with the first width. 
     
     
         8 . The method of  claim 7 , wherein forming the at least one Si fin with the second width comprises:
 etching the substrate to form the at least one Si fin with the second width; and   selectively removing the spacer layer from the at least one SiGe fin with the first width.   
     
     
         9 . The method of  claim 4 , wherein oxidizing comprises removing a portion of Si from the at least one SiGe fin with the first width and the at least one Si fin with the second width. 
     
     
         10 . The method of  claim 9 , wherein oxidizing the at least one Si fin with the second width creates an oxide layer isolating the at least one SiGe fin with the target width from the substrate. 
     
     
         11 . The method of  claim 9 , wherein a height of the at least one SiGe fin with the target width is reduced after oxidizing. 
     
     
         12 . The method of  claim 4 , wherein:
 the at least one Si fin is formed directly below the at least on SiGe fin; and   the oxidizing results without a need for employing a punchthrough stopping region under the at least one SiGe fin to suppress source/drain punchthrough.   
     
     
         13 . A method, comprising:
 forming at least one silicon-germanium (SiGe) fin with a first width from an SiGe layer on a substrate;   forming at least one Si fin with a second width from an upper portion of the substrate; and   oxidizing the at least one SiGe fin with the first width, the at least one Si fin with the second width and a surface of the substrate below the at least one Si fin, wherein the first width of the at least one SiGe fin is condensed in width to a target width.   
     
     
         14 . The method of  claim 13 , wherein the at least one Si fin is completely oxidized forming an oxide layer between the at least one SiGe fin and the substrate. 
     
     
         15 . The method of  claim 14 , wherein the oxidizing results in a higher percentage of Ge in the at least one SiGe fin with the target width than a percentage of Ge in the SiGe layer, the target width is less than the second width, and the second width is less than the first width. 
     
     
         16 . The method of  claim 15 , further comprising:
 selectively removing the oxide layer from side surfaces of the at least one SiGe fin.   
     
     
         17 . The method of  claim 16 , further comprising:
 depositing a nitride liner on a surface of a remaining portion of the oxide layer; and   depositing a flowable oxide layer on the nitride layer,   wherein forming the SiGe layer comprises epitaxially growing the SiGe layer on a top surface of the substrate.   
     
     
         18 . The method of  claim 16 , wherein forming the at least one SiGe fin with a first width comprises:
 forming a masking layer on a top surface of the SiGe layer; and   etching the at least one SiGe fin with the first width.   
     
     
         19 . The method of  claim 18 , further comprising forming a spacer layer on the at least one SiGe fin with the first width. 
     
     
         20 . The method of  claim 19 , wherein:
 forming the at least one Si fin with the second width comprises:
 etching the substrate to form the at least one Si fin with the second width; and 
 selectively removing the spacer layer from the at least one SiGe fin with the first width; 
   oxidizing comprises removing a portion of Si from the at least one SiGe fin with the first width and the at least one Si fin with the second width;   oxidizing the at least one Si fin with the second width creates an oxide layer isolating the at least one SiGe fin with the target width from the substrate;   a height of the at least one SiGe fin with the target width is reduced after oxidizing;   the at least one Si fin is formed directly below the at least on SiGe fin; and   the oxidizing results without a need for employing a punchthrough stopping region under the at least one SiGe fin to suppress source/drain punchthrough.