A high density capacitive pressure sensor array for fingerprint sensor application

This paper reports on the first technological and electrical results on the sensitive part of a fingerprint sensor which consists of an X-Y array of absolute pressure capacitive sensitive cells with a pitch of 50 μm. Manufacturing is carried out using a specific CMOS compatible silicon surface micromachining process. Very good cell sensitivity homogeneity has been measured at a wafer level thanks to an automatic probe test. Pressure sensor geometrical parameters and membrane material Young modulus have been deduced from tests on individual cells. Results are in good agreement with theory and have been confirmed by deflexion interferometric measurements