Subtractive nanomanufacturing is essential for high-precision device fabrication, but conventional techniques rely on resource-intensive processes and environmentally hazardous materials. Here, we introduce Optothermal Bubble Etch Lithography (OBEL), a single-step, maskless technique that enables localized, high-resolution patterning with minimal chemical and thermal damage. OBEL uses a low-power continuous-wave laser focused on a gold film to generate microbubbles at the substrate-liquid interface, which locally concentrate etchant ions for spatially selective etching. Solutal Marangoni convection actively removes bubbles and generated debris, yielding clean and sharply defined features. Operating at ultralow etchant concentrations (0.05 M), OBEL achieves complex planar patterns with submicron (∼450 nm) resolution. This environmentally friendly, cost-effective lithography method offers a scalable alternative for micro- and nanoscale fabrication across electronics, photonics, and biomedical applications.
Swain et al. (Mon,) studied this question.