Ru thin film grown by metal organic chemical vapor deposition (MOCVD) was applied in this study as a substrate for superconformal Cu electrodeposition as well as a Cu diffusion barrier at a Cu/Ru/SiO2/Si multilayer system for microelectronics. Bis (ethyl-pi-cyclopentadienyl) Ru-based MOCVD Ru thin film had a roughness of about 12% of its thickness and well-developed textures with high purity. It also showed good step coverage in damascene trench structure. Pd catalyst-mediated Cu electrodeposition on Ru surface. accomplished formation of continuous Cu film. For Gap filling in single damascene structure. bumps indicative of bottom-up acceleration and superfilling were observed during two-step Cu electrodeposition on Ru substrate which involved seeding and filling with conventional three additives system. 30 nm-thick Ru film effectively worked as a barrier for interdiffusion and/or reaction between layers even after annealing at 800 degreesC for 30 min. With the exception of slight agglomeration of Cu at elevated temperature, no silicidation or AES-profile broadening was observed in a Cu/Ru/SiO2/Si system. (C) 2004 American Vacuum Society.