Electrodeposition of Silver and Copper/Silver Multilayer on Ruthenium Substrate as a Potential New Metal Interconnect for Integrated Circuits

As the demand for faster and cheaper integrated circuits prevalent in today’s technology continues to rise, there is a challenge to produce even smaller and faster circuits in less time and for less cost. Our work explores the superior conductivity of silver metal for the application as a more conductive metal interconnects in next generation integrated circuits. In this work, ruthenium was chosen as the diffusion barrier platform on which a precise and uniform coating of silver would be deposited electrochemically. However, the adhesion testing revealed poor adhesion between deposited Ag thin film and its Ru substrate. The adhesion problem was corrected by installing a thin Cu priming layer on Ru prior to Ag deposition. A two-steps Ag plating protocol was developed to overcome the unwanted Ag displacement reaction with Cu and achieved the preparation of Ag/Cu/Ru multiplayer, which showed good adhesion after peel test.