A sandwich type of capacitive MEMS acceleration sensor used for device-level vacuum packaging is designed.The sensor is made of four-layer silicon wafers bonded together while the top and bottom wafers are the fixed electrodes and the cantilever-mass structure is made on the middle two wafers.Two grooves are etched in the middle mass block bonding layer by self-stopped etching process and used to remove air from cavity within the acceleration sensor

creating vacuum environment in subsequent packaging.A double-sided dicing process is developed to protect V-shaped grooves from water or silicon scrap.The total size of the sensor is 6.8 mm×5.6 mm×1.72 mm and the size of mass is 3.2 mm×3.2 mm×0.86 mm.The interval of detecting capacitor is 2.1 μm.The performance of the device-level vacuum packaged sensor is tested.The C-V plot is normal and the sensitivity is about 1.53V/gn.The resonant frequency is 861 Hz and quality factor Q is 76.The fine leakage of He is lower than 1×10-9atm-cm3/s and has no bubbles during gross leakage test.