Fabrication of high aspect ratio channels in fused silica using femto-second pulses and chemical etching at different conditions

Abstract

In this work we present an in-depth investigation of the direct writing and chemical etching method emphasizing the importance of the parameters of the etchant. Different etching scenarios are examined when 3D structures are written with different laser parameters in the bulk of fused silica samples which are later etched in an aqueous KOH solution. The temperature of the etchant as well as the concentration was varied. The etching rate as well as the selectivity was measured for all of the different cases. Our results demonstrate, that changing the temperature of the etchant only by 30 deg. C can increase the etching rate by several times, however, the selectivity of the etching process deteriorates in this case.