Controllable and Nanoscale Linear Etching of Atomic Layer Deposited Molybdenum Using Cyclic Stepwise CHF 3 /O 2 Plasma

ABSTRACT Precise nanoscale control of molybdenum (Mo) etching is critical for state‐of‐the‐art interconnects, 3D NAND, and other key applications like back‐side power delivery network. Herein, we demonstrate a controllable, nanoscale etching process for Mo films using a cyclic stepwise CHF 3 /O 2 plasma approach. Compared to continuous etching, cyclic stepwise etching achieves exceptional etching linearity (R 2 = 0.999) with a precisely tunable etch depth per cycle ranging from 0.74 nm/cycle at 45 W to 1.71 nm/cycle at 90 W. Furthermore, the cyclic process significantly improves surface quality, reducing root‐mean‐square roughness by 8.8% and peak‐to‐valley roughness by 24.3% compared to the as‐deposited film. Surface analysis and density functional theory calculations reveal that the process is enabled by a dynamic synergy between surface oxidation and polymer‐regulated fluorination. Comprehensive characterization results suggest that the cyclic etching process preserves the crystalline structure and chemical purity of the remaining Mo film. This work provides a promising pathway toward precise and tunable Mo etching processes for the next‐generation Mo‐based interconnect architectures.