Barrierless ALD Molybdenum for Buried Power Rail and Via-to-Buried Power Rail metallization
Anshul Gupta, Jan Willem Maes, Nicolas Jourdan, C. Zhu, Sukanya Datta, Olalla Varela Pedreira, Quoc Toan Le, D. Radisic, N. Heylen, Antoine Pacco, Shouhua Wang, Moataz Mousa, Young Byun, F. C. Seidel, Bart De Wachter, Gayle Murdoch, Zsolt Tökei, E. Dentoni Litta, Naoto Horiguchi
Abstract
This work reports for the first time, a middle-of-line (MOL) compatible, barrier/liner-less ALD molybdenum (Mo) process on SiO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> used for Via-to-buried-power-rail (VBPR) and contact-to-active (M0A) dual-damascene metallization. We also compare the MOL-compatible ALD process with the front-end-of-line (FEOL)-compatible ALD process used for BPR fill as reported in [1]. In addition, we report that Mo-BPR can withstand 800 °C anneal, demonstrating its compatibility with high thermal budgets of FEOL. Furthermore, we demonstrate for the first time, integrated (i.e. w/o air-break) precleans prior to Mo-VBPR deposition for contact formation with Mo-BPR. The precleans remove MoO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</inf> from Mo-BPR surface proven by SIMS characterization at blanket film level. The effectiveness of precleans is further proven at via level with a good agreement between measured and predicted Mo-VBPR resistance (R) landing on Mo-BPR. Finally, the first downstream electromigration tests on Mo-BPR annealed at 800 °C, show no failures for >150 h at 5 MA/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> & 330 °C proving its robust behavior.