Silicon-germanium-carbon compositions and processes thereof

Abstract

Silicon-germanium-based compositions comprising silicon, germanium, and carbon (i.e., Si—Ge—C), methods for growing Si—Ge—C epitaxial layer(s) on a substrate, etchants especially suitable for Si—Ge—C etch-stops, and novel methods of use for Si—Ge—C compositions are provided. In particular, the invention relates to Si—Ge—C compositions, especially for use as etch-stops and related processes and etchants useful for microelectronic and nanotechnology fabrication.

What is claimed is:  
     
         8 . A method for using Si—Ge—C in selective etch applications in conjunction with a silicon substrate, comprising: 
 growing one or more epitaxial layers sequentially, starting at the silicon substrate, wherein at least one of the epitaxial layers comprises Si—Ge—C, wherein the carbon of the Si—Ge—C layer is about 4.5 atomic percent; and  
 selectively etching the one or more layers adjacent to the Si—Ge—C layer and/or the Si—Ge—C layer wherein the selective etching includes applying a KOH etchant to the Si—Ge—C layer.  
 
     
     
         10 . The method of  claim 8 , wherein the Si—Ge—C layer etches slower than the one or more adjacent layers.  
     
     
         12 . The method of  claim 8 , wherein the Si—Ge—C layer etches slower than the silicon substrate.  
     
     
         16 . A method for using Si—Ge—C in selective etch applications in conjunction with a silicon, germanium, or silicon-germanium substrate, comprising: 
 growing one or more epitaxial layers sequentially, starting at the substrate, at least one of which comprises Si—Ge—C, wherein carbon is present in the Si—Ge—C layer(s) in an amount sufficient for etch selectivity with respect to the substrate and/or adjacent epitaxial layers; and  
 etching the one or more layers adjacent to the Si—Ge—C layer or the Si—Ge—C layer or the substrate with HNA, wherein the carbon content is greater than 2 percent.  
 
     
     
         25 . The method of  claim 8 , wherein the etchant is 10-45 wt % KOH—H 2 O and is maintained at a temperature in the range of 50 to 100° C.  
     
     
         27 . The method of  claim 8 , wherein the etchant is 21 wt % KOH—H 2 O and is maintained at a temperature in the range of 50 to 100° C.  
     
     
         45 . A method of forming a silicon-on-insulator material, the method comprising the steps of: 
 forming a Si—Ge—C epitaxial layer having a carbon concentration greater than 2 percent, sufficient to function as an etch-stop, wherein the Si—Ge—C resides on a surface of a first semiconductor silicon substrate;    forming a second silicon epitaxial layer on the Si—Ge—C alloy layer;    providing a first oxide layer on a surface of the second epitaxial layer;    providing a second oxide layer on a second semiconductor silicon substrate;    bringing into contact the first and second oxide layers thereby bonding together the first and second semiconductor substrates to thereby form a laminated structure;    removing most of the first silicon substrate;    exposing the laminate to a first etchant which preferentially etches the first silicon substrate until the remainder of the first silicon substrate is removed, but only a part of the Si—Ge—C layer is removed; and    exposing the resultant structure to [a second etchant] HNA which preferentially etches the Si—Ge—C layer for a time sufficient only to remove the remainder of the Si—Ge—C layer thereby producing a silicon-on-insulator material.    
     
     
         47 . The method of claim  16  or  45 , wherein the carbon is in the range of 4-5 atomic percent.  
     
     
         48 . The method of claim  16  or  45 , wherein the carbon is about 4.5 atomic percent.