| Summary: | 碩士 === 國立臺灣師範大學 === 光電科技研究所 === 101 === In this study, we investigated the silver metallization technology and feasibility of Ti-based diffusion barrier for Back-Eend-of-Line (BEOL) interconnect application. A single ALD-TiN film with bi-functional diffusion barrier and plating seed layer was developed. By way of the surface modification of TiN film with energetic plasma bombardment and DHF immersion, the wetting behavior for electroplating Ag film was effectively modified. We successfully plating Ag on treated TiN film without any catalyst or seed layer prior to the Ag deposition. Junction leakage current measurement using n+/p-Si diode showed that the titanium nitride can effectively prevent silver diffusion even after 400oC anneal process.
To integrate the Ag and ALD-TiN barrier process, bottom-up Ag electroplating surrounding by TiN film was proposed. Line width of 350, 400 and 450 nm was formed via Photolithography. Post plating Ag line with distributed grain size was not as smooth as sputtering film. It is believed that the pre-treatment is necessary for better wettability and microstructure.
Except the bottom-up Ag electroplating, traditional damascene metal plating was checked for electroplating condition tuning. A tapered plug with 150nm top-opening and 84nm bottom width was prepared for Ag gap-filling. We found that the seam or central void will be left without any additive added in the electrolyte. That is, the study of additive in the future will be an important issue in realizing Ag metallization.
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