Cap layer for pad oxidation prevention

A semiconductor structure, comprising:

• a first integrated circuit (IC) die;
• and
• a second IC die bonded to the first IC die at a bond interface;
• wherein the first IC die comprises:
• an interconnect pad;
• a bond pad at the bond interface;
• a bond contact extending from the bond pad to a surface of the interconnect pad;
• a cap layer covering the surface of the interconnect pad around the bond contact;
• and
• a dielectric layer separating the cap layer from the bond pad;
• and
• wherein the cap layer is dielectric and comprises carbon, wherein a hardness of the cap layer is less than a hardness of the dielectric layer.

A method for forming a semiconductor structure, comprising:

• forming a semiconductor device on a substrate;
• forming an interconnect structure over the substrate, wherein the interconnect structure comprises an interconnect pad exposed at a top of the interconnect structure and electrically coupled to the semiconductor device;
• depositing a cap layer covering the interconnect pad;
• pushing a probe through the cap layer to the interconnect pad;
• performing a test on the semiconductor device via the probe and the interconnect pad;
• and
• forming a bond structure over and electrically coupled to the interconnect pad after the performing of the test.