Fabrication of microchannels and through-holes in Borofloat glass using Cr thin film with positive photoresist as the masking layer through wet etching

The present work investigates the efficiency of the masking layer, composed of Cr thin film and positive photoresist (AZ1512HS), to fabricate microchannels and through-holes in Borofloat glass wafers via wet etching, utilizing 20 % HF. The initial phase of the work emphasizes microchannel fabrication. ∼50 µm deep and well-defined microchannels are accomplished with no discernible surface defects on the wafer. In the later phase, predominantly sharp-edged through-holes are successfully fabricated in the wafer, without any observable pinholes, during etching for 300 min. The masking layer constantly exhibited robust adhesion to the wafer throughout the etching process, affirming its effectiveness. This work demonstrates the first instance of fabricating 500 µm deep through-holes in glass with Cr thin film and photoresist as a masking layer.