Monolithic fingerprint sensor

摘要

The apparatus includes a layer of polycrystalline silica (35) deposited on a silica substratum (30) with an anti-graving layer (33). The polycrystalline silica layer is then photoengraved to leave portions at each micro pick-up. Further layers of silica resistant to engraving (36) and polycrystalline silica (38) are added. The polycrystalline silica layer (38) is engraved to form a Wheatstone Bridge of piezoelectric resistances at each micro pick-up and holes (42) allow part of the original polycrystalline silica layer (35) to be removed by an engraving liquid (KOH). This leaves a diaphragm (46) above a cavity (44).