MEMS fingerprint sensor with arrayed cavity structures

We propose a MEMS (Micro Electro Mechanical Systems) fingerprint sensor whose pixels have novel cavity structures. Each cavity structure has a sensitive plane of a thin film on top, and a sensing circuit below it. Ridges on a finger surface bend the thin film mechanically, which is detected by the sensing circuit electronically. We fabricated the sensor using a CMOS compatible process with our sealing technique. The sensor can obtain fingerprint images of even dry or wet fingers. It also shows sufficient mechanical strength against finger pressure. These results confirm that the MEMS fingerprint sensor has the potential for wide practical application.