Photoelectrochemical etching of semiconductor induced by evanescent light

Abstract A novel photoelectrochemical etching method for semiconductor was introduced, utilizing evanescent light as the source to confine the etching depth. Evanescent light, generated under total internal reflection, is localized near the reflective interface. Since the etching rate correlates with light intensity, the etching profile is determined by the spatial decay of the evanescent field from the interface. Time-resolved measurements revealed that the etching depth is limited to approximately 900 nm from the total internal reflection interface. The shape of the etched cavity reflects the intensity distribution of the evanescent light. In addition, a theoretical model was developed based on the hypothesis that the etching rate is proportional to the light intensity when using evanescent light. The experimental etching results are consistent with this theoretical model. These findings suggest that consistent etching profiles can be achieved regardless of the initial surface morphology under optimized conditions, as the evanescent light intensity distribution is independent of surface topography. This etching technology has the potential to enable non-contact or zero-defect surface flattening.