Patent ID: 10647570

Abstract:
A process for fabricating a symmetrical MEMS accelerometer. A pair of half parts is fabricated by, for each half part: (i) forming a plurality of resilient beams, first connecting parts, second connecting parts, and a plurality of comb structures, by etching a plurality of holes on a bottom surface of a first silicon wafer; (ii) etching a plurality of hollowed parts on a top surface of a second silicon wafer; (iii) forming a silicon dioxide layer on the top and bottom surface of the second silicon wafer; (iv) bonding the bottom surface of the first silicon wafer with the top surface of the second silicon wafer; (v) depositing a layer of silicon nitride on the bottom surface of the second silicon wafer, and removing parts of the silicon nitride layer and silicon dioxide layer on the bottom surface of the second silicon wafer; (vii) deep etching the exposed parts of the bottom surface of the second silicon wafer to the silicon dioxide layer located on the top surface of the second silicon wafer, and reducing the thickness of the first silicon wafer; and (viii) removing the silicon nitride layer, and etching the silicon dioxide to form the mass. The two half parts are then bonded along their bottom surface. The device is deep etched to form a movable accelerometer. A bottom cap is fabricated by hollowing out the corresponding area, and depositing metal as electrodes. The accelerometer is bonded with the bottom cap. Metal is deposited on the first silicon wafer to form electrodes.