Damascene Cu electrodeposition on metal organic chemical vapor deposition-grown Ru thin film barrier

Abstract

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-p-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 °C 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.