Wafer-bonding structure and method of forming thereof

Abstract

A method of forming a wafer-bonding structure includes a wafer-bonding step, a through silicon via (TSV) forming step, and a forming bonding pad step. In the wafer-bonding step, at least two wafers are corresponding to and bonded to each other by bonding surfaces thereof. In the TSV forming step, a TSV structure is formed on at least one side of a seal ring structure of one of the wafers, a conductive filler is disposed in the TSV structure, and the TSV structure is overlapped the side of one of the seal ring structure of one of the wafers and a portion of a seal ring structure of another one of the wafers. In the forming bonding pad step, a bonding pad is formed on an outer surface which is relative to the bonding surface of the wafer with the TSV structure, so as to form the wafer-bonding structure.

1 . A method of forming a wafer-bonding structure, comprising:
 a wafer-bonding step, wherein at least two wafers are corresponding to and bonded to each other by bonding surfaces thereof;   a through silicon via (TSV) forming step, wherein a TSV structure is formed on at least one side of a seal ring structure of one of the at least two wafers, a conductive filler is disposed in the TSV structure, and the TSV structure is overlapped the at least one side of the seal ring structure of one of the at least two wafers and a portion of a seal ring structure of another one of the at least two wafers; and   a forming bonding pad step, wherein a bonding pad is formed on an outer surface which is relative to the bonding surface of the wafer with the TSV structure, so as to form the wafer-bonding structure.   
     
     
         2 . The method of forming the wafer-bonding structure of  claim 1 , further comprising:
 a surface treatment step, wherein the bonding surface of each of the at least two wafers is performed a surface treatment before the wafer-bonding step.   
     
     
         3 . The method of forming the wafer-bonding structure of  claim 1 , wherein the at least two wafers are exposed to a nitrogen plasma or an oxygen plasma in the wafer-bonding step. 
     
     
         4 . The method of forming the wafer-bonding structure of  claim 1 , wherein the at least two wafers are bonded at 250° C. to 350° C. for 1 hour to 3 hours in the wafer-bonding step. 
     
     
         5 . The method of forming the wafer-bonding structure of  claim 1 , wherein the at least two seal ring structures are aligned to each other in the wafer-bonding step. 
     
     
         6 . The method of forming the wafer-bonding structure of  claim 5 , wherein an alignment accuracy of the wafer-bonding step is below 300 nm. 
     
     
         7 . A wafer-bonding structure, comprising:
 at least two wafers, which are bonded to each other, each of the at least two wafers having a bonding surface, and each of the at least two wafers comprising:   a seal ring structure, disposed in the wafer, an end of the seal ring structure connected to the bonding surface, and the other end of the seal ring structure connected to an outer surface of the wafer;   a through silicon via (TSV) structure, passed through from the outer surface to the bonding surface in one of the at least two wafers, wherein the TSV structure is connected to and overlapped at least one side of the seal ring structure of one of the at least two wafers and a portion of the seal ring structure of another one of the at least two wafers;   a conductive filler, disposed in the TSV structure; and   a bonding pad, disposed on the outer surface of the wafer with the TSV structure.   
     
     
         8 . The wafer-bonding structure of  claim 7 , wherein each of the seal ring structures comprises:
 a first metal layer, connected to the bonding surface;   at least one metal layer, disposed between the outer surface and the first metal layer; and   at least two pin sets, one of the least two pin sets connected to the first metal layer and the at least one metal layer, the other one of the at least two pin sets connected to the at least one metal layer and the outer surface, wherein each of the at least two pin sets comprises at least three pins.   
     
     
         9 . The wafer-bonding structure of  claim 8 , wherein a range of the TSV structure straddled the first metal layer is larger than or equal to 0.05 μm. 
     
     
         10 . The wafer-bonding structure of  claim 8 , wherein a range of the TSV structure straddled the at least one metal layer is larger than or equal to 0.02 μm. 
     
     
         11 . The wafer-bonding structure of  claim 8 , wherein a width of each of the at least three pins is larger than or equal to 0.025 μm. 
     
     
         12 . The wafer-bonding structure of  claim 8 , wherein the first metal layer and the at least one metal layer are made of copper. 
     
     
         13 . The wafer-bonding structure of  claim 8 , wherein a width of the first metal layer is larger than a width of the at least one metal layer. 
     
     
         14 . The wafer-bonding structure of  claim 7 , wherein a depth of the TSV structure is 2 μm to 20 μm. 
     
     
         15 . The wafer-bonding structure of  claim 7 , wherein a width of the TSV structure is 0.1 μm to 10 μm. 
     
     
         16 . The wafer-bonding structure of  claim 7 , wherein the conductive filler is made of copper. 
     
     
         17 . The wafer-bonding assembly of  claim 7 , wherein the bonding pad is made of aluminum.