Wafer gettering using relaxed silicon germanium epitaxial proximity layers

Abstract

One aspect of this disclosure relates to a method for creating proximity gettering sites in a semiconductor wafer. In various embodiments of this method, a relaxed silicon germanium region is formed to be proximate to a device region on the semiconductor wafer. The relaxed silicon germanium region generates defects to getter impurities from the device region. In various embodiments, an ultra high vacuum chemical vapor deposition (UHV CVD) process is performed to epitaxially form the relaxed silicon germanium gettering region. In various embodiments, forming the relaxed silicon germanium gettering region includes implanting germanium ions into a silicon substrate with a desired dose and energy to form a silicon region containing germanium ions and heat treating the substrate to regrow a crystalline silicon layer over a resulting silicon germanium layer using a solid phase epitaxial (SPE) process. Other aspects are provided herein.

1 . A method, comprising: 
 defining a device region in a silicon wafer;    generating desired defects in the silicon wafer and proximate to the device region to provide a gettering site proximate to the device region, including forming a relaxed silicon germanium region in the silicon wafer and proximate to the device region; and    forming a device in the device region, and gettering the device region to diffuse unwanted impurities from the device region to the gettering site when the device is formed.    
   
   
       2 . The method of  claim 1 , wherein generating desired defects includes epitaxially forming the relaxed silicon germanium gettering region.  
   
   
       3 . The method of  claim 1 , wherein generating desired defects includes implanting germanium ions into the silicon wafer and heat treating to form a crystalline silicon layer over a silicon germanium layer.  
   
   
       4 . The method of  claim 1 , wherein generating desired defects includes bonding the silicon germanium region to the silicon wafer.  
   
   
       5 . The method of  claim 1 , wherein forming the device includes forming the device in a strained crystalline silicon layer having a thickness within a range of approximately 300 Å to 1000 Å.  
   
   
       6 . A method, comprising: 
 defining a device region in a silicon wafer;    generating desired defects, by relaxation of the silicon germanium lattice strain or injection of silicon interstitials, in the silicon wafer and proximate to the device region to provide a gettering site proximate to the device region, including forming a relaxed silicon germanium region in the silicon wafer and proximate to the device region; and    forming a device in the device region, and gettering the device region to diffuse unwanted impurities from the device region to the gettering site when the device is formed.    
   
   
       7 . The method of  claim 6 , wherein generating desired defects includes generating desired defects by relaxation of the silicon germanium lattice strain and injection of silicon interstitials when the device is formed.  
   
   
       8 . The method of  claim 6 , wherein forming the device includes forming the device in a strained crystalline silicon layer having a thickness less than approximately 2000 Å.  
   
   
       9 . The method of  claim 6 , wherein generating desired defects includes epitaxially forming the relaxed silicon germanium gettering region.  
   
   
       10 . The method of  claim 6 , wherein generating desired defects includes implanting germanium ions into the silicon wafer using a first implant of a first desired dose and energy and a second implant of a second desired dose and energy, and heat treating to form a crystalline silicon layer over a silicon germanium layer.  
   
   
       11 . The method of  claim 6 , wherein generating desired defects includes bonding the silicon germanium region to the silicon wafer using a bond cut process.  
   
   
       12 . A method, comprising: 
 defining a device region in a silicon wafer;    generating desired defects in the silicon wafer and proximate to the device region to provide a gettering site proximate to the device region, including forming a relaxed silicon germanium region in the silicon wafer and proximate to the device region; and    forming a device on the gettering site in the device region, and gettering the device region to diffuse unwanted impurities from the device region to the gettering site when the device is formed.    
   
   
       13 . The method of  claim 12 , wherein forming the device includes forming the device in a strained crystalline silicon layer having a thickness less than approximately 2000 Å.  
   
   
       14 . The method of  claim 12 , wherein generating desired defects includes epitaxially forming the relaxed silicon germanium gettering region using an ultra high vacuum chemical vapor deposition (UHV CVD) process).  
   
   
       15 . The method of  claim 12 , wherein generating desired defects includes implanting germanium ions into the silicon wafer and heating treating with a temperature within a range from approximately 550° C. to approximately 700° C. to form a crystalline silicon layer over a silicon germanium layer.  
   
   
       16 . The method of  claim 12 , wherein generating desired defects includes bonding the silicon germanium region to the silicon wafer using a bond cut process.  
   
   
       17 . A method, comprising: 
 defining a device region in a silicon wafer;    generating desired defects in the silicon wafer and proximate to the device region to provide a gettering site proximate to the device region, including forming a relaxed silicon germanium region in the silicon wafer and proximate to the device region; and    forming a device in a strained silicon layer in the device region, and gettering the device region to diffuse unwanted impurities from the device region to the gettering site when the device is formed.    
   
   
       18 . The method of  claim 17 , wherein the strained silicon layer has a thickness less than approximately 1000 Å.  
   
   
       19 . The method of  claim 17 , wherein generating desired defects includes epitaxially forming the relaxed silicon germanium gettering region.  
   
   
       20 . The method of  claim 17 , wherein generating desired defects includes implanting germanium ions into the silicon wafer and heat treating to form a crystalline silicon layer over a silicon germanium layer.  
   
   
       21 . The method of  claim 17 , wherein generating desired defects includes bonding the silicon germanium region to the silicon wafer.