Technology of electroplating copper with low-K material a-C : F for 0.15 mu m damascene interconnection

Abstract

In our work, fluorinated amorphous carbon films (a-C:F) was deposited by PECVD. The amorphous carbon films (a-C:F) with low dielectric constant (K similar to2.3), thermal stability (higher than 400 degreesC) and acceptable adhesion to cap-layer such as SiOF was obtained by optimum of content ration between carbon with fluorine and adding few SiH4 for improvement of adhesion. The etching profile with high aspect ratio and etching selection ration more than 50 (a-C:F/SiOF) were obtained by etching gas of N-2+O-2. Furthermore, we demonstrated the technology of electroplating copper in trenches or vias as small as 0.15 mum, 6:1 AR The wetting agent system was consisted of mainly two molecular weights polyethylene glycols (PEG). The small molecular weight PEG (200) with better diffusion ability for reducing the surface tension and the larger PEG (2000) enhancing grain growth control was proposed for the first time to wet the inner portion of the sub-150 nm damascene feature. The leveling agent system was mainly heterocyclic compound contained N, S atoms offering sufficient activation over-potential and selective inhibition gradient.