Fingerprint detector with improved sensing surface layer

摘要

A fingerprint detector having a smooth sensing surface for contact with a fingerprint includes capacitive sensor plates defining an array of sensor cells below the sensing surface and tungsten ESD protection grid lines surrounding each sensor cell. The sensing surface is defined by an alumina layer with the tungsten grid lines embedded therein. The alumina layer provides a sensing surface with improved scratch resistance. The resulting detector is more sensitive in its capacitive sensing due to the relatively high dielectric constant of the alumina layer.