Electromigration-resistant lead-free solder interconnect structures

A method of forming an interconnect structure comprising:

• providing a semiconductor substrate having a metal layer;
• forming a copper pedestal having a first end coupled to the metal layer, at least one side, and a second end;
• forming a barrier layer on the copper pedestal;
• forming a barrier protection layer on the barrier layer;
• forming a solder layer on the barrier protection layer;
• and
• pressing a mold over the solder layer so that the solder layer directly contacts one or more of the at least one side of the copper pedestal.

A method of forming an interconnect structure comprising:

• providing a semiconductor substrate having a metal layer;
• forming a copper pedestal having a first end coupled to the metal layer, at least one side, and a second end;
• forming a barrier layer on the copper pedestal;
• forming a barrier protection layer on the barrier layer;
• filling a mold with a solder;
• and
• transferring the solder from the mold to the copper pedestal, wherein the solder at least partially covers the barrier protection layer and directly contacts one or more of the at least one side of the copper pedestal.

A method of forming a semiconductor structure comprising:

• providing a semiconductor substrate having a metal layer;
• forming a copper pedestal having a first end coupled to the metal layer, at least one side, and a second end;
• forming a barrier layer on the copper pedestal;
• forming a barrier protection layer on the barrier layer;
• forming a solder layer, wherein the solder layer at least partially covers the barrier protection layer and contacts one or more of the at least one side of the copper pedestal;
• and
• reflowing the solder layer.

A method of forming an interconnect structure comprising:

• providing a semiconductor substrate having a metal layer;
• forming a copper pedestal having a first end coupled to the metal layer, at least one side, and a second end;
• forming a barrier layer on the copper pedestal;
• forming a barrier protection layer on the barrier layer;
• forming a solder layer on the barrier protection layer wherein the solder layer directly contacts one or more of the at least one side of the copper pedestal.