Abstract
An out-of-plane sensing device is provided. A proof mass is movable with respect to a substrate. A frame is positioned on the substrate and encloses the proof mass. At least one spring connects the proof mass to the frame so that the spring will exert a force on the proof mass to make the proof mass move back to its equilibrium position when the proof mass moves perpendicularly to the substrate. An electrode extends from the proof mass toward the frame. A counter electrode extends from the frame toward the proof mass, wherein the projection of the electrode onto the substrate overlaps with that of the counter electrode onto the substrate.