Semiconductor structure and method of forming the same

Abstract

A method of forming a semiconductor structure includes following steps. A first wafer is bonded to a second wafer, in which the first wafer includes a first substrate and a first conductive pad above a first surface of the first substrate, and the second wafer comprises a second substrate and a second conductive pad above a second surface of the second substrate. A mask layer is formed above the first substrate. The mask layer and the first substrate are etched to form a first opening in the first substrate. A sacrificial spacer is formed in the first substrate at a sidewall of the first opening. The first conductive pad is etched to form a second opening communicated to the first opening. A conductive material is filled in the first opening and the second opening to form a conductive structure interconnecting the first and second conductive pads.

1 - 15 . (canceled) 
     
     
         16 . A semiconductor structure, comprising:
 a first wafer comprising:
 a first substrate having a first surface; and 
 a first conductive pad above the first surface of the first substrate; 
   a second wafer above the first surface of the first substrate of the first wafer, and the second wafer comprises a second conductive pad;   a conductive structure in the first substrate of the first wafer and extending upward from the second conductive pad, wherein the conductive structure has a top portion in contact with the first conductive pad and a bottom portion in contact with the second conductive pad; and   a liner layer has a first portion and a second portion apart from the first portion, wherein the first portion of the liner layer is between the first conductive pad and the conductive structure and a top surface of the first portion of the liner layer is substantially coplanar with a top surface of the first conductive pad.   
     
     
         17 . The semiconductor structure of  claim 16 , wherein the first conductive pad and the second conductive pad are aluminum conductive pads. 
     
     
         18 . The semiconductor structure of  claim 16 , wherein the top portion of the conductive structure has a width greater than that of the bottom portion of the conductive structure. 
     
     
         19 . The semiconductor structure of  claim 16 , further comprises:
 a bonding layer between the first wafer and the second wafer, and the bonding layer is in contact with the first conductive pad and the second conductive pad.   
     
     
         20 . The semiconductor structure of  claim 19 , wherein the first portion of the liner layer is further on a sidewall of the bonding layer.