Pure-Metal Replacement Gate for Reliable 30 nm Pitch Scaled 3D NAND Flash
S. Rachidi, S. Ramesh, Davide Tierno, Gabriele Luca Donadio, Antoine Pacco, Jan Willem Maes, Yongbin Jeong, Antonio Arreghini, Geert Van den Bosch, M. Rosmeulen · 2024
We demonstrate the integration of Molybdenum as "a pure metal gate" in a record 30 nm z-pitch 3D NAND device by adopting a barrierless replacement metal gate (RMG) process. We also propose and demonstrate an in-memory-hole high-k (HK) liner to extend the 3D NAND Flash roadmap. In the new structure, the HK liner is placed inside the memory hole instead of the word-line (WL) cavity, thereby freeing up room for WL metal and enabling vertical scalability. Mo conductivity improves with a H2-only post metallization anneal. We report good channel control down to 15 nm Mo WL thickness. Superior retention is obtained for devices with Mo in combination with 2 nm HfO2liner. No impact of z-pitch scaling on reliability down to 30 nm pitch.