HIGHLY COMPLIANT PLATE FOR WAFER BONDING
The present invention discloses a method that includes: providing two wafers; forming raised contacts on the two wafers; aligning the two wafers; bringing together the raised contacts; locally deflecting the two wafers; and bonding the raised contacts. The present invention also discloses a bonded-wafer structure that includes: a first wafer, the first wafer being locally deflected, the first wafer including a first raised contact; and a second wafer, the second wafer being locally deflected, the second wafer including a second raised contact, wherein the second raised contact is bonded to the first raised contact.
1 . A method comprising:
providing two wafers;
forming raised contacts on said two wafers;
reducing thickness of said two wafers;
pretreating a surface of said raised contacts;
aligning said two wafers;
bringing together said raised contacts;
locally deflecting said two wafers; and
bonding said raised contacts.
2 . The method of claim 1 wherein said two wafers comprise partial wafers.
3 . The method of claim 1 wherein said raised contacts are located on the faces of said two wafers.
4 . The method of claim 1 wherein said locally deflecting of said two wafers is accomplished with a highly compliant plate.
5 . The method of claim 4 wherein said highly compliant plate comprises a fluid to apply pressure to non-bonding sides of said wafers.
6 . The method of claim 5 wherein said highly compliant plate further comprises a compliant barrier to separate said fluid from said non-bonding sides of said wafers, said compliant barrier comprising a flexible membrane.
7 . The method of claim 5 wherein said fluid may be a gas.
8 . A method comprising:
providing a first wafer, said first wafer having a first raised contact;
stacking a second wafer over said first wafer, said second wafer and said first wafer being structurally and functionally dissimilar, said second wafer having a second raised contact, said second raised contact facing said first raised contact;
applying different pressure concurrently to said first wafer and said second wafer to locally deflect said first wafer and said second wafer; and
heating said first wafer and said second wafer to bond said first raised contact and said second raised contact.
9 . The method of claim 8 wherein said first wafer and said second wafer comprise partial wafers.
10 . A method comprising: providing a first wafer having raised contacts located on a face and a second wafer having raised
contacts located on a back;
bringing together said face of said first wafer and said back of said second wafer;
partially bonding said two wafers face-to-back;
sealing edges of said two wafers; and
bonding raised contacts on said two wafers in a pressurized and heated chamber.
11 . The method of claim 10 wherein said sealing of said edges is accomplished with copper sealing rings.
12 . The method of claim 10 wherein said sealing of said edges is accomplished with an underfill.
13 . The method of claim 10 wherein said two wafers comprise partial wafers.