In this study, we investigate multiple etchants and laser parameters. Interestingly, we show that there is an optimal energy dose one order of magnitude smaller than the currently used ones, and notably, at a regime where nanogratings are not yet formed. This energy dose yields higher process efficiency and lower processing time, and this, with unprecedented aspect ratio levels. We further demonstrate that for low dose exposure is the formation of laser-induced bond matrix defects in the glass matrix and not the presence of nanogratings that drives the etching selectivity.
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