FIG. 4 also illustrates under bump metallization (UBM) structures 147 formed over and electrically coupled to the redistribution structure 140. To form the UBM structures 147, openings are formed in the topmost dielectric layer (e.g., 142) of the redistribution structure 140 to expose conductive features (e.g., copper lines or copper pads) of the redistribution structure 140. After the openings are formed, the UBM structures 147 may be formed in electrical contact with the exposed conductive features. In an embodiment, the UBM structures 147 comprise three layers of conductive materials, such as a layer of titanium, a layer of copper, and a layer of nickel. However, there are many suitable arrangements of materials and layers, such as an arrangement of chrome/chrome-copper alloy/copper/gold, an arrangement of titanium/titanium tungsten/copper, or an arrangement of copper/nickel/gold, that are suitable for the formation of the UBM structures 147. Any suitable materials or layers of material that may be used for the UBM structures 147 are fully intended to be included within the scope of the present disclosure.