Semiconductor device and fabrication method thereof

A semiconductor device comprising:

• a semiconductor substrate having a first surface, a second surface opposed to the first surface, and a circuit element on the first surface;
• an electrode pad disposed on the first surface of the semiconductor substrate, electrically coupled to the circuit element;
• a first metal layer patterned to cover the electrode pad;
• a first conductive pattern on the first metal layer;
• a protective layer that seals the first-surface side of the semiconductor substrate, and that has an opening exposing part of the first conductive pattern;
• an electrode covering said opening, the electrode being electrically coupled to the exposed part of the first conductive pattern;
• an interlayer dielectric film disposed between the protective layer and the first surface of the semiconductor substrate, having a through hole extending to the electrode pad;
• and
• a conductive nub disposed between the first conductive pattern and the first metal layer below the opening in the protective layer,
• the first conductive pattern including a first part on the conductive nub and projecting from the opening in the protective layer, a second part in the through hole, and a third part on the interlayer dielectric film to link the first and second parts,
• the electrode is a bump electrode on the first part of the first conductive pattern.