Atomic-layer precision etching of SiO2 using sequential molecular adsorption and plasma activation

Abstract

As device architectures in electronics, photonics, and quantum technologies scale reach atomic dimensions, precise and controllable material processing becomes essential. However, achieving atomic-layer precision in materials etching, even in silicon dioxide (SiO2), remains a major challenge for next-generation nanofabrication. Here, we present a cyclic process that integrates sequential sulfur hexafluoride (SF6) molecular adsorption with argon (Ar) plasma activation, enabling a stable etch-per-cycle (EPC) of ~1.4 Å/cycle and 100% synergy between modification and removal steps. Mechanistic studies combining experiments, ab initio molecular dynamics, and density functional theory reveal that etching proceeds via a combination of reversible physisorption and defect-mediated chemisorption. Moreover, detailed morphology characterization over multiple cycles reveals a directional and uniform etching effect. This work introduces a scalable, contamination-free, precise etching strategy using standard reactive ion etching (RIE) equipment and commercially available gases, offering a robust and transferable platform for next-generation nanofabrication.