Patent ID: 7309924

Claim:
A flip-chip package comprising: a first wafer having a first electrode and a first under bump metal (UBM) formed on the first electrode and electrically connected to the first electrode; a second wafer opposing said first wafer and having a second electrode aligned with the first electrode, and a second UBM formed on the second electrode and electrically connected to the second electrode; and a solder ball connecting the first and second UBMs, wherein the first wafer comprises a depression formed on one or more areas adjacent to the first UBM, which depression partly receives the solder ball connecting the first and the second UBMs upon flip-chip bonding of the first and second wafers, wherein the depression has a sidewall adjacent to the first UBM that is slanted by a predetermined angle, and wherein the first UBM extends to said sidewall; further comprising a third UBM separated from the first UBM by a predetermined distance, said third UBM being formed on said sidewall and being electrically connected to the first electrode.