High Hermeticity and Long Lifetime MEMS Alkali Vapor Cells for Atomic Sensors

Most chip-scale atomic sensors in quantum precision measurement fields require MEMS alkali vapor cells with long lifetime operation, which is mainly restricted by the significant reduction in alkali metal in the vapor cells. An integrated circuit compatible fabrication process is proposed to realize high hermetic alkali metal cesium vapor cells with passivation layers to prevent the reduction in alkali metal. The fabricated vapor cells achieve leakage rates less than 1 × 10−13 Pa·m3/s, and can maintain cesium content well in a two-step high-temperature accelerated aging process of 115 °C for more than 2 years and 300 °C for 48 h. The high-temperature aged vapor cells are tested and assembled in miniaturized atomic clocks for trial use. The resonance performance tests indicate that the coherent population trapping widths of the vapor cells are less than 2 kHz, and the corresponding atomic clocks realize pretty good short-term stabilities of about 8.68 × 10−11 @ 1 s and 6.83 × 10−12 @ 1000 s. All results indicate that the vapor cells have long lifetime application potential in chip-scale atomic sensing devices.