Capacitive micro inclinometer with scalloping-free and footing-free vertical electrodes using crystalline etching of (110) silicon

A micromachined capacitive inclinometer has been developed to detect inclination angles for a position sensing application. In order to enhance resolution, a (110) crystalline silicon-on-patterned-insulator (COPI) process has been proposed to remove the morphologic defects such as footing and scalloping which were formed from silicon deep reactive ion etching (DRIE) process. The sidewalls fabricated by the (110) COPI process remarkably became vertical and flat with few nanometer roughness. The micro inclinometer with flat and vertical sensing electrodes was evaluated in terms of capacitance change and detection limit. The capacitance change of the fabricated device is from −0.246 to 0.258 pF for the inclination angle (−90° to 90°). The temporal deviation of the capacitance is as small as 0.2 fF, which leads to 0.3 or less resolution for ±70°.