| abstract |
An integrated circuit structure includes a first work piece and a second work piece. The first work piece includes a copper bump at a main surface of the first work piece and having a first dimension; and a nickel-containing barrier layer over and adjoining the copper bump. The second work piece is bonded to the first work piece and includes a bond pad at a main surface of the second work piece; and a solder mask at the main surface of the second work piece and having a solder resist opening with a second dimension exposing a portion of the bond pad. A ratio of the first dimension to the second dimension is greater than about 1. Further, a solder region electrically connects the copper bump to the bond pad, with a vertical distance between the bond pad and the copper bump being greater than about 30 μm. |