Room-Temperature Radical–Complexation Wet Etch Chemistry Demonstrated on VO2

Abstract

Despite advances in metal oxide device technology, etching strategies remain limited by the difficulty of achieving high pattern fidelity under low thermal budgets. Here, we present a room-temperature wet etching strategy for VO2 thin films based on a HCl/H2O2 system that couples radical-assisted oxidation with chloride complexation. In this chemistry, H2O2 promotes low-barrier oxidation, while chloride complexation facilitates the continuous dissolution of oxidized vanadium species, enabling efficient material removal without external thermal activation. Compared with conventional APS and HF/HNO3 etchants, the HCl/H2O2 system achieves a high VO2 etch rate of 5.64 nm min–1, a VO2-to-sapphire substrate selectivity of 806:1, and a minimized total lateral width loss of 0.47 µm, corresponding to a ∼2.7–2.9× increase in selectivity and a ∼1.8–2.0× reduction in lateral loss. Structural, morphological, and electrical analyses support the preservation of intrinsic VO2 properties after etching. Device-level measurements further show that improved etching quality reduces switching variability, with up to ∼38% reduction compared with conventional etching processes, particularly at reduced channel widths. More importantly, these results establish a direct process–structure–device relationship for oxide electronics, demonstrating how mechanism-driven wet chemistry can simultaneously improve pattern fidelity, material preservation, and device reproducibility. This work provides a practical framework for designing reliable fabrication processes in functional oxide devices.