Improvement in etching efficiency of borosilicate glass by dissolving internal silver precipitates

Abstract Solid-state ion exchange with an applied voltage enables metal doping into alkali-silicate glass surfaces. The effect is especially prominent when silver is a dopant material, with additional voltage application producing silver nanowire networks in a glass substrate. We aimed to improve the wet etching efficiency of a glass substrate using internal networks as penetration paths of etchants. Silver precipitated glass when immersed in hydrofluoric acid (HF), allowing etchant infiltration via cracks around the nanowires. As a result, the silver-precipitated area was selectively dissolved, due to which blind/through-holes were formed with similar shapes. The etch rate (etched depth per unit time) of the silver-precipitated area was 1.9 μm/min, and was 3.3 times higher than that of the as-received glass (0.58 μm/min) in 20 wt% HF at 297 K.