WAFER BONDING METHOD AND WAFER STACK FORMED THEREBY
First Claim
1. A wafer bonding process comprising:
- providing a first bonding site on a surface of a first wafer;
depositing at least a first bonding stack on a surface of a second wafer;
forming at least a first groove in the surface of the first wafer, the first groove either surrounding the first bonding site or lying entirely within the first bonding site;
aligning and mating the first and second wafers so that the first bonding stack on the second wafer contacts the first bonding site on the first wafer; and
thenheating the first and second wafers to reflow the first bonding stack on the second wafer, form a molten bonding material, cause at least a portion of the molten bonding material to flow into the first groove in the surface of the first wafer, and form a first bonding structure that bonds to the first bonding site of the first wafer and bonds the second wafer to the first wafer.
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Accused Products
Abstract
A wafer bonding process that compensates for curvatures in wafer surfaces, and a wafer stack produced by the bonding process. The process entails forming a groove in a surface of a first wafer, depositing a bonding stack on a surface of a second wafer, aligning and mating the first and second wafers so that the bonding stack on the second wafer contacts a bonding site on the first wafer, and then heating the first and second wafers to reflow the bonding stack. The groove either surrounds the bonding site or lies entirely within the bonding site, and the heating step forms a molten bonding material, causes at least a portion of the molten bonding material to flow into the groove, and forms a bonding structure that bonds the second wafer to the first wafer. Bonding stacks having different lateral surface areas can be deposited to form bonding structures of different heights to compensate for variations in the wafer gap.
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Citations
40 Claims
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1. A wafer bonding process comprising:
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providing a first bonding site on a surface of a first wafer; depositing at least a first bonding stack on a surface of a second wafer; forming at least a first groove in the surface of the first wafer, the first groove either surrounding the first bonding site or lying entirely within the first bonding site; aligning and mating the first and second wafers so that the first bonding stack on the second wafer contacts the first bonding site on the first wafer; and
thenheating the first and second wafers to reflow the first bonding stack on the second wafer, form a molten bonding material, cause at least a portion of the molten bonding material to flow into the first groove in the surface of the first wafer, and form a first bonding structure that bonds to the first bonding site of the first wafer and bonds the second wafer to the first wafer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A wafer stack comprising:
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first and second wafers; a first bonding site on a surface of the first wafer; a first groove in the surface of the first wafer, the first groove either surrounding the first bonding site or lying entirely within the first bonding site; a first bonding structure bonded to the first bonding site of the first wafer and bonding the second wafer to the first wafer, at least a portion of the first bonding structure being present in the first groove in the surface of the first wafer. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36)
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37. A wafer bonding process comprising:
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providing first and second bonding sites on a surface of a first wafer; depositing at least first and second bonding stacks on a surface of a second wafer, the first bonding stack having a larger surface area than the second bonding stack; aligning and mating the first and second wafers so that the first and second bonding stacks on the second wafer contact the first and second bonding sites on the first wafer, respectively, the first and second wafers defining an interface therebetween and a gap between the surfaces of the first and second wafers, the gap having a width that is greater at a first location of the interface at which the first bonding stack and the first bonding site are located than at a second location of the interface at which the second bonding stack and the second bonding site are located; and
thenheating the first and second wafers to reflow the first and second bonding stacks on the second wafer, form a molten bonding material, and form first and second bonding structures that bond to the first and second bonding sites of the first wafer and bond the second wafer to the first wafer. - View Dependent Claims (38, 39, 40)
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Specification