A 0.1µM-Resoution Silicon Tactile Sensor with Precisely Designed Piezoresitve Sensing Structure

In this paper, a newly developed ultra-high resolution tactile sensor with a spatial resolution of 0.1μm and a force resolution of 60μN is reported for the first time. The ultrahigh resolution tactile sensor is required for quality control of finished metal surface and painted surface of automobiles that are not replaced by “non-contact” optical measurements. A 0.1μm spatial resolution is realized by a needle-like contactor-tip precisely formed by deep-RIE. A 60μN force resolution is realized by partly narrowed silicon spring. Also, piezoresistors were arranged to maximize the stress sensitivity considering the crystal orientation dependency on piezoresistive effect. The fabricated new device in this study has realized 6 times higher performance in vertical displacement and 40 times higher performance in frictional force resolution than the tactile sensor device that we reported in 2018 [1]. Measured surface shape corresponded well to the actual surface shape in deep sub-micron region.