Fingerprint detector with scratch resistant surface and embedded ESD protection grid

摘要

A fingerprint detector having a smooth sensor surface for contact with a fingerprint includes capacitive sensor plates defining an array of sensor cells below the sensor surface and tungsten ESD protection grid lines surrounding each sensor cell. The sensor surface is defined by silicon carbide and includes silicon oxide filling cavities in the silicon carbide. The cavities inherently result from processing steps, including removal of the tungsten atop the silicon carbide that is used to define the grid lines. Filling the cavities with oxide and smoothing the surface using chemical mechanical polishing provides a scratch-resistant surface and improves the sensitivity of the capacitive sensor cells.