Pillar bump with noble metal seed layer for advanced heterogeneous integration

A method of forming a semiconductor structure, comprising:

• forming, on a semiconductor substrate, a blanket liner followed by a seed layer comprising a noble metal;
• forming a hardmask layer above the seed layer;
• forming a first photoresist layer directly above the hardmask layer;
• forming a first plurality of openings extending from the first photoresist layer through the hardmask layer to expose the seed layer;
• removing the first photoresist layer;
• forming a protective layer within the first plurality of openings;
• depositing a first conductive material within each of the first plurality of openings to form first pillar bumps, the protective layer being located along opposing sidewalls of each of the first pillar bumps;
• forming a metal cap above and in direct contact with a top surface of each of the first pillar bumps;
• removing the hardmask layer from the semiconductor structure;
• and
• removing portions of the seed layer extending outward from the first pillar bumps, wherein a portion of the seed layer remains underneath the first pillar bumps.