Method to selectively cap interconnects with indium or tin bronzes and/or oxides thereof and the interconnect so capped

A method to selectively coat a copper substrate with a Cu-based alloy comprising:

• providing a copper substrate having at least one exposed Cu surface;
• providing an immersion deposition bath wherein said bath comprises a plating metal comprised of In or Sn, and wherein said bath further comprises a copper complexing agent;
• immersing said copper substrate in said immersion deposition bath hereby forming on said copper substrate a metal film comprised of said plating metal;
• and
• annealing said metal film at an elevated temperature of at least 200° C. in an inert or reducing ambient, forming said Cu-based metal alloy.