Thermally stable crystalline defect-free germanium boned to silicon and silicon dioxide

Abstract

A wafer pair comprising a substantially defect-free germanium wafer and methods of making the same. The wafer pair comprises the substantially defect-free germanium wafer directly bonded to a silicon wafer. The method of making the wafer pair comprises placing the silicon wafer in a wafer-bonding chamber, placing the germanium wafer on top or on bottom of the silicon wafer, and applying a local force to either the germanium wafer or to the silicon wafer to initiate bonding of the germanium wafer to the silicon wafer. The bonding occurs under a temperature ranging from about 23° C. to about 600° C. and under a vacuum condition inside a wafer-bonding chamber.

We claim:  
     
         1 . A method of forming a substantially defect-free germanium film on a semiconductor wafer comprising: 
 placing a semiconductor wafer in a wafer-bonding chamber;    placing a germanium wafer on top of or on bottom of said semiconductor wafer; and    applying a local force to one of said germanium wafer and said semiconductor wafer to initiate bonding of said germanium wafer to said semiconductor wafer, said bonding forms a wafer pair.    
     
     
         2 . A method as in  claim 1  further comprising: 
 annealing said wafer pair after said germanium wafer is bonded to said semiconductor wafer.  
 
     
     
         3 . A method as in  claim 2  wherein an annealing temperature for said annealing ranges from 180° C. to 600° C.  
     
     
         4 . A method as in  claim 1  further comprising: 
 thinning said germanium wafer bonded to said semiconductor wafer to a desired thickness.  
 
     
     
         5 . A method as in  claim 1  wherein said semiconductor wafer is selected from a group consisting of a silicon wafer and a silicon wafer having a silicon oxide layer formed thereon.  
     
     
         6 . A method as in  claim 1  wherein said applying a local force to one of said germanium wafer and said semiconductor wafer comprises: 
 applying a force ranging from 3 Newton to 4000 Newton to a region near an edge of said one of said germanium wafer and said semiconductor wafer.  
 
     
     
         7 . A method as in  claim 1  further comprising: 
 cleaning said semiconductor wafer before said placing of said semiconductor wafer into said wafer-bonding chamber; and  
 cleaning said germanium wafer before said placing said germanium wafer on said top or on said bottom of said semiconductor wafer.  
 
     
     
         8 . A method as in  claim 1  further comprising: 
 obtaining an appropriate bonding condition for said wafer-bonding chamber.  
 
     
     
         9 . A method as in  claim 8  wherein said obtaining said appropriate bonding condition includes obtaining a desired bonding temperature and a desired bonding pressure.  
     
     
         10 . A method as in  claim 9  wherein said desired bonding temperature ranges from 22° C. to 600° C.  
     
     
         11 . A method as in  claim 11  wherein said desired bonding pressure is a sub-atmospheric pressure to place said wafer-bonding chamber under a vacuum condition.  
     
     
         12 . A method of forming a substantially defect-free germanium film on a semiconductor wafer comprising: 
 cleaning a silicon wafer;    cleaning a germanium wafer;    placing said silicon wafer in a wafer-bonding chamber;    placing said germanium wafer on top or on bottom of said silicon wafer;    applying a local force to a region near an edge of one of said germanium wafer and said silicon wafer to initiate bonding of said germanium wafer to said silicon wafer, said bonding forming a wafer pair; and    annealing said wafer pair after said germanium wafer is bonded to said silicon wafer.    
     
     
         13 . A method as in  claim 12  further comprising: 
 thinning said germanium wafer bonded to said silicon wafer to a desired thickness.  
 
     
     
         14 . A method as in  claim 12  wherein an annealing temperature for said annealing ranges from 100° C. to 600° C., wherein a bonding temperature for said wafer-bonding chamber ranges from 22° C. to 600° C., and wherein a bonding pressure for said wafer-bonding chamber is less than 1 Torr.  
     
     
         15 . A method as in  claim 12  wherein said applying a local force to one of said germanium wafer and said silicon wafer comprises applying a force ranging from 3 Newton to 4000 Newton.  
     
     
         16 . A method as in  claim 12  wherein said silicon wafer comprises a silicon oxide layer.  
     
     
         17 . A wafer pair for integrating into an electronic device comprising: 
 a silicon wafer; and    a germanium wafer directly bonded to said silicon wafer wherein said germanium wafer is substantially defect-free.    
     
     
         18 . A wafer pair as in  claim 17  wherein said silicon wafer further comprises an oxide layer.  
     
     
         19 . A wafer pair as in  claim 17  wherein said substantially defect-free includes defect free at an interface of said wafer pair.  
     
     
         20 . A wafer pair as in  claim 17  wherein said substantially defect-free includes thermally stable, slip free, and void-free.  
     
     
         21 . A wafer pair as in  claim 17  wherein said substantially defect-free includes said germanium wafer having no hysteresis.  
     
     
         22 . A wafer pair as in  claim 17  wherein said substantially defect-free includes said germanium wafer having a compressive stress at a temperature greater than 300° C. during a heating up of said wafer pair.  
     
     
         23 . A wafer pair as in  claim 17  wherein said substantially defect-free includes said germanium wafer having fracture limit at a temperature less than 300° C. during a cooling down of said wafer pair.  
     
     
         24 . A wafer pair as in  claim 17  said germanium wafer is bonded to said silicon wafer through a use of a local force applying to one of said germanium wafer and said silicon wafer when said germanium wafer is placed on top or on bottom of said silicon wafer.  
     
     
         25 . A wafer pair as in  claim 24  wherein germanium wafer is bonded to said silicon wafer in a wafer-bonding chamber with a temperature ranging from about 23° C. to about 600° C. and with a pressure under a vacuum condition.  
     
     
         26 . A wafer pair as in  claim 25  wherein germanium wafer is thinned down to a desired thickness after being directly bonded to said silicon wafer.  
     
     
         27 . A wafer pair as in  claim 26  wherein said desired thickness is less than 150 μm.