Co-W nanocrystalline electrodeposits as barrier for interconnects
Tsyntsaru, N. × Kaziukaitis, G. Yang, C. Cesiulis, H. Philipsen, H. G. G. Lelis, M. Celis, Jean-Pierre #
Journal of Solid State Electrochemistry vol:x issue:x pages:1-8
This study was performed in order to investigate a possibility to obtain Co-W microbumps via electrochemical
routes, because this alloy recently has gained attraction as a novel barrier against copper diffusion. In order to be applied in flip-chip technology, barrier layers should be void-free and uniformly deposited on the entire area of a die to ensure high reliability and high performance of wafer bump-solder interface. To meet these requirements, a set of potentiostatic and galvanostatic electrodeposition was carried out from a citrate electrolyte, at pH 5 and at room temperature. The tests done confirm that void-free Co-W bumps with a uniform tungsten content along the bump can be obtained by potentiostatic and galvanostatic electrodeposition. Successful electrodeposition
of Cu/Co-W/Sn layers with good adhesion between them and
uniformity on the entire array of bumps also was obtained.
The XPS data confirm that electrodeposited Co-W layers can
act as a good barrier between Sn and Cu.