Buried Power Rail Metal exploration towards the 1 nm Node
Anshul Gupta, D. Radisic, Jan Willem Maes, Olalla Varela Pedreira, J-P. Soulie, N. Jourdan, Hans Mertens, S. Bandyopadhyay, Quoc Toan Le, Antoine Pacco, N. Heylen, K. Vandersmissen, K. Devriendt, C. Zhu, Sukanya Datta, Farid Sebaai, S. Wang, Moataz Mousa, J. Lee, J. Geypen, B. De Wachter, Bilal Chehab, Shairfe Muhammad Salahuddin, Gayle Murdoch, S. Biesemans, Zs. Tôkei, E. Dentoni Litta, Naoto Horiguchi
Abstract
This work reports metal exploration for buried power rail (BPR) and Via-to-BPR (VBPR) towards the 1 nm node. For tungsten, which is the first choice of BPR metal at the 3 nm node, we optimize W metallization stack to minimize line resistivity, together with ways to reduce W-BPR - W-VBPR contact resistance (R). For scaled BPR CDs at the 2 nm and 1 nm nodes, we introduce molybdenum at the BPR level and benchmark its R and electromigration against W and Ru metallization. Additionally, Mo dry & wet, selective etch processes to enable Mo-BPR recess in fin/STI stack at fin pitch 24 nm, and a Mo wet clean process for VBPR contact formation are also demonstrated.