QUASI-HYDROPHOBIC Si-Si WAFER BONDING USING HYDROPHILIC Si SURFACES AND DISSOLUTION OF INTERFACIAL BONDING OXIDE

Abstract

Methods for removing or reducing the thickness of a material layer remaining at Si-Si interfaces after silicon wafer bonding. The methods include an anneal which is performed at a temperature sufficient to dissolve oxide, yet not melt silicon.

1 . A method for reducing the thickness of a material layer comprising at least one of C, Ge, N, O or Si between two bonded silicon surfaces comprising annealing a structure including said material layer comprising at least one of C, Ge, N, O or Si between said two bonded silicon surfaces at a temperature sufficient to dissolve oxide, yet not melt silicon. 
     
     
         2 . The method of  claim 1  wherein said two bonded silicon surfaces comprise a first silicon surface with a first single crystal surface orientation and a second silicon surface with a second single crystal surface orientation, said second single crystal surface orientation is different from said first single crystal surface orientation. 
     
     
         3 . The method of  claim 1  wherein said temperature is from about 1200° to about 1400° C. 
     
     
         4 . The method of  claim 3  wherein said annealing is performed at said temperature for a time period from about 0.1 to about 24 hours. 
     
     
         5 . The method of  claim 1  wherein said annealing is performed in an ambient comprises at least one gas selected from the group consisting of Ar, He, Kr, Ne, Xe, N 2 , O 2 , H 2 , H-containing gases, C-containing gases, F-containing gases, Cl-containing gases, Si-containing gases, halogen-containing gases, O-containing gases, and mixtures thereof. 
     
     
         6 . The method of  claim 5  wherein said ambient is oxidizing. 
     
     
         7 . The method of  claim 1  further comprising depositing a disposable protective cap layer before said annealing and removing said disposable protective cap layer after said annealing. 
     
     
         8 . The method of  claim 1  further comprising removing any surface oxide layer produced during said annealing by wet etching. 
     
     
         9 . A method for reducing the thickness of an interfacial oxide between a bonded silicon surface and a silicon-containing semiconductor surface comprising annealing a structure including said interfacial oxide between said two bonded surfaces at a temperature sufficient to dissolve oxide, yet not melt silicon. 
     
     
         10 . The method of  claim 9  wherein said two bonded silicon surfaces comprise a first silicon surface with a first single crystal surface orientation and a second silicon surface with a second single crystal surface orientation, said second single crystal surface orientation is different from said first single crystal surface orientation. 
     
     
         11 . The method of  claim 9  wherein said temperature is from about 1200° to about 1400° C. 
     
     
         12 . The method of  claim 11  wherein said annealing is performed at said temperature for a time period from about 0.1 to about 24 hours. 
     
     
         13 . The method of  claim 9  wherein said annealing is performed in an ambient comprising at least one gas selected from the group consisting of Ar, He, Kr, Ne, Xe, N 2 , O 2 , H 2 , H-containing gases, C-containing gases, F-containing gases, Cl-containing gases, Si-containing gases, halogen-containing gases, O-containing gases, and mixtures thereof. 
     
     
         14 . The method of  claim 9  wherein said annealing is performed in an oxidizing ambient. 
     
     
         15 . The method of  claim 9  further comprising depositing a disposable protective cap layer before said annealing and removing said disposable protective cap layer after said annealing. 
     
     
         16 . The method of  claim 9  further comprising removing any surface oxide layer produced during said annealing utilizing a wet etching. 
     
     
         17 . A method of fabricating a semiconductor structure comprising: annealing a bonded structure including an interfacial oxide between two bonded silicon surfaces in an ambient that is selected from the group consisting of O 2 , H 2 , H-containing gases, C-containing gases, F-containing gases, Cl-containing gases, Si-containing gases, halogen-containing gases, O-containing gases, and mixtures thereof, and at a temperature sufficient to dissolve oxide, yet not melt silicon. 
     
     
         18 . The method of  claim 17  wherein said two bonded silicon surfaces comprise a first silicon surface with a first single crystal surface orientation and a second silicon surface with a second single crystal surface orientation, said second single crystal surface orientation is different from said first single crystal surface orientation. 
     
     
         19 . The method of  claim 17  wherein said temperature is from about 1200° to about 1400° C. 
     
     
         20 . The method of  claim 17  wherein said annealing is performed at said temperature for a time period from about 0.1 to about 24 hours.