A semiconductor structure includes a substrate, a bond pad over the substrate, and a passivation layer over the substrate and a peripheral region of the bond pad. The bond pad has a bonding region and the peripheral region surrounding the bonding region. The passivation layer has an opening defined therein, and the opening exposes the bonding region of the bond pad. A first vertical distance between an upper surface of the passivation layer and a surface of the bonding region ranges from 30% to 40% of a second vertical distance between a lower surface of the passivation layer and an upper surface of the peripheral region.