Optimization of laser process method and HF-based chemical etchants for laser-induced deep etching of NXT glass

Corning Lotus NXT glass exhibits advanced optical properties and high thermal and dimensional stability, setting industry-leading standards in applications such as displays, medical devices, and sensors. Acid-based glass etching techniques have been widely used for decades to shape glasses suitable for target applications with acceptable surface properties. In this work, we optimized the effect of different hydrofluoric acid-based chemical solutions to etch NXT glass by the laser-induced deep etching (LIDE) technique with a focus on the etching speed, aspect ratio, and quality of the obtained surface. The results show that a volumetric ratio of 7:3 of HF to HNO₃ achieved a higher etching speed ($\sim 850$ $\mu$m/h) and aspect ratio ($\sim$19:1) under laser conditions of 1030 nm wavelength, 45 $\mu$J pulse energy, $2\times 10^4$ shots, and a 40 kHz repetition rate, compared to other etching solutions in the LIDE process. The surface roughness of the etched samples treated with the three different acid solutions was analyzed using atomic force microscopy (AFM). The analysis revealed that all etched samples maintained surface roughness with RMS values below 1 nm. These results demonstrate the superior efficacy of this etching combination in achieving optimal etching speeds, aspect ratios, and ultra-smooth surface topography, making it suitable for display applications.