Packaging assembly and method of making the same

A packaging assembly, comprising:

• a semiconductor device, wherein the semiconductor device comprises:
• a conductive pad having a first width,
• a conductive pillar over the conductive pad, wherein the conductive pillar has a second width greater than the first width, and
• a cap layer over the conductive pillar, wherein the cap layer exposes sidewalls of the conductive pillar layer;
• a substrate, wherein the substrate comprises:
• a conductive region, and
• a mask layer over the conductive region, wherein the mask layer defines an opening exposing a portion of the conductive region;
• and
• a joint structure electrically connecting the conductive pillar and the conductive region wherein the joint structure extends through the opening.

A method of making a packaging assembly, the method comprising:

• depositing an under bump metallization (UBM) layer over a conductive pad of a semiconductor device, wherein the conductive pad has a first width;
• depositing a mask layer over the UBM layer;
• patterning the mask layer to define an opening having a second width greater than the first width;
• forming a conductive pillar in the opening;
• depositing a cap layer over the conductive pillar in the opening;
• removing the mask layer;
• and
• bonding the conductive pillar to a conductive region of a substrate using a joint structure, wherein the cap layer is between the conductive pillar and the joint structure.