Methods of forming semiconductor structures comprising direct bonding of substrates

Abstract

The invention relates to a method of initiating molecular bonding, comprising bringing one face of a first wafer to face one face of a second wafer and initiating a point of contact between the two facing faces. The point of contact is initiated by application to one of the two wafers, for example using a bearing element of a tool, of a mechanical pressure in the range 0,1 MPa to 33.3 MPa.

1 . A method of forming a three-dimensionally integrated structure, comprising:
 directly contacting a surface of a first substrate with a surface of a second substrate;   applying mechanical pressure in a range extending from 0.1 MPa to 33.3 MPa to at least one of the first substrate and the second substrate; and   initiating and propagating a bonding wave across an interface between the surface of a first substrate and the surface of the second substrate resulting in the formation of a direct inter-atomic bonds between the surface of the first substrate and the surface of the second substrate.   
     
     
         2 . The method of  claim 1 , wherein applying mechanical pressure in a range extending from 0.1 MPa to 33.3 MPa to at least one of the first substrate and the second substrate comprises applying mechanical pressure in a range extending from 0.1 MPa to 10 MPa to at least one of the first substrate and the second substrate. 
     
     
         3 . The method of  claim 2 , wherein applying mechanical pressure in a range extending from 0.1 MPa to 10 MPa to at least one of the first substrate and the second substrate comprises applying mechanical pressure in a range extending from 2 MPa to 5 MPa to at least one of the first substrate and the second substrate. 
     
     
         4 . The method of  claim 1 , wherein applying mechanical pressure comprises applying the mechanical pressure over a contact surface area of 5 mm 2  or less. 
     
     
         5 . The method of  claim 4 , further comprising applying the mechanical pressure over a contact surface area of 1 mm 2  or less. 
     
     
         6 . The method of  claim 5 , further comprising applying the mechanical pressure over a contact area in a range extending from 0.3 mm 2  to 1 mm 2  between a tool and a surface of the at least one of the first substrate and the second substrate, and exerting a bearing force in a range extending from 0.1 N to 10 N on the surface of the of the at least one of the first substrate and the second substrate by the tool. 
     
     
         7 . The method of  claim 6 , further comprising providing a polymer material on at least an end of the tool intended to bear on the surface of the at least one of the first substrate and the second substrate. 
     
     
         8 . The method of  claim 1 , further comprising providing an oxide material on at least one of the surface of the first substrate and the surface of the second substrate prior to directly contacting the surface of the first substrate with the surface of the second substrate. 
     
     
         9 . The method of  claim 1 , further comprising forming a first plurality of microcomponents on the surface of the first substrate prior to directly contacting the surface of the first substrate with the surface of the second substrate. 
     
     
         10 . The method of  claim 9 , further comprising forming a second plurality of microcomponents on an exposed surface of the second substrate after formation of the direct inter-atomic bonds between the surface of the first substrate and the surface of the second substrate. 
     
     
         11 . The method of  claim 10 , further comprising vertically aligning at least some microcomponents of the second plurality of microcomponents with at least some of the first plurality of microcomponents and limiting unintended horizontal offsets between the vertically aligned microcomponents of the first and second pluralities of microcomponents to values less than 200 nm. 
     
     
         12 . The method of  claim 11 , further comprising limiting the unintended horizontal offsets between the vertically aligned microcomponents of the first and second pluralities of microcomponents to values less than 100 nm. 
     
     
         13 . The method of  claim 10 , further comprising limiting the unintended horizontal offsets between the vertically aligned microcomponents of the first and second pluralities of microcomponents to values less than 200 nm in a homogenous manner over the entire three-dimensionally integrated structure. 
     
     
         14 . The method of  claim 10 , further comprising forming at least some microcomponents of the first plurality of microcomponents to comprise image sensors. 
     
     
         15 . The method of  claim 14 , further comprising forming at least some microcomponents of the second plurality of microcomponents to comprise color filters. 
     
     
         16 . The method of  claim 10 , further comprising forming at least some microcomponents of the second plurality of microcomponents to comprise at least one of contact points and interconnections. 
     
     
         17 . The method of  claim 1 , further comprising selecting the first substrate to comprise an SOI structure. 
     
     
         18 . A method of forming a semiconductor structure, comprising:
 directly contacting a surface of a first wafer with a surface of a second wafer;   applying mechanical pressure in a range extending from 0.1 MPa to 33.3 MPa to at least one of the first wafer and the second wafer; and   establishing a direct bond between the surface of the first wafer and the surface of the second wafer, the direct bond resulting from atomic interactions at the interface between the surface of the first wafer and the surface of the second wafer.   
     
     
         19 . The method of  claim 18 , wherein establishing a direct bond between the surface of the first wafer and the surface of the second wafer comprises initiating and propagating a bonding wave across an interface between the surface of a first wafer and the surface of the second wafer. 
     
     
         20 . The method of  claim 19 , wherein applying mechanical pressure in a range extending from 0.1 MPa to 33.3 MPa to at least one of the first wafer and the second wafer comprises applying mechanical pressure in a range extending from 0.1 MPa to 10 MPa to at least one of the first wafer and the second wafer. 
     
     
         21 . The method of  claim 20 , wherein applying mechanical pressure in a range extending from 0.1 MPa to 10 MPa to at least one of the first wafer and the second wafer comprises applying mechanical pressure in a range extending from 2 MPa to 5 MPa to at least one of the first wafer and the second wafer. 
     
     
         22 . The method of  claim 18 , wherein applying mechanical pressure comprises applying the mechanical pressure over a contact surface area of 5 mm 2  or less. 
     
     
         23 . The method of  claim 22 , further comprising applying the mechanical pressure over a contact surface area of 1 mm 2  or less. 
     
     
         24 . The method of  claim 23 , further comprising applying the mechanical pressure over a contact area in a range extending from 0.3 mm 2  to 1 mm 2  between a tool and the at least one of the first wafer and the second wafer, and exerting a bearing force in a range extending from 0.1 N to 10 N on the at least one of the first wafer and the second wafer by the tool. 
     
     
         25 . The method of  claim 18 , further comprising forming a first plurality of microcomponents on the surface of the first wafer prior to directly contacting the surface of the first wafer with the surface of the second wafer. 
     
     
         26 . The method of  claim 25 , further comprising forming a second plurality of microcomponents on an exposed surface of the second wafer after establishing the direct bond between the surface of the first wafer and the surface of the second wafer. 
     
     
         27 . The method of  claim 26 , further comprising vertically aligning at least some microcomponents of the second plurality of microcomponents with at least some of the first plurality of microcomponents and limiting unintended horizontal offsets between the vertically aligned microcomponents of the first and second pluralities of microcomponents to values less than 200 nm.