Patent ID: 8603862

Claim:
A bonding method, comprising the steps of: providing a first bonding structure having at least one copper pad embedded in a first insulator and at least one via in the first insulator over the copper pad, wherein the via has tapered sidewalls; providing a second bonding structure having at least one copper stud embedded in a second insulator, wherein a portion of the copper stud is exposed for bonding and has a domed shape which is obtained by polishing the exposed portion of the copper stud to obtain the domed shape; placing bonder clips between the first bonding structure and the second bonding structure; bringing the first bonding structure and the second bonding structure together; removing the bonder clips; and bonding the first bonding structure to the second bonding structure by way of a copper-to-copper bonding between the copper pad and the copper stud, wherein the copper stud and the via have complementary shapes in that during the bonding step the copper stud engages the via such that the tapered sidewalls of the via shift the first bonding structure and the second bonding structure relative to one another thereby self-aligning the copper stud with the copper pad, wherein the bonding step comprises: i) applying a first bonding force, ii) increasing temperature until a bonding temperature is reached, and iii) applying a second bonding force, wherein the second bonding force is greater than the first bonding force.