芯片级原子束钟真空腔技术研究

Research on Vacuum Chamber of Chip-scale Atomic Beam Clocks

  • 摘要: 近年来,一系列技术(包括激光冷却、光子集成和真空技术)的进步,使得原子束钟的微型化成为可能。芯片级原子束钟兼具现有微波原子束钟的高频率稳定性和CPT芯片原子钟的小体积、低功耗,具有很好的综合优势。国内有关芯片级原子束钟的报道很少。对芯片级原子束钟真空腔的关键制备技术进行系统研究,包括束源区、束漂移区以及微型准直通道阵列的微加工,以及多层微型真空腔结构的高气密封装。通过中间电极引出技术和阳极键合工艺的整体优化,减少并弱化了多层键合过程中反向电场对已形成键合面的损害,实现了高质量五层玻璃-硅键合结构。研究结果为实现高频率稳定度芯片级原子束钟,以及其他量子器件系统奠定了基本工艺基础。

     

    Abstract: As two commonly used time-frequency reference devices today, the well-developed microwave atomic beam clocks have the disadvantages of large size and high-power consumption, while the chip-scale coherent population trapping (CPT) atomic clocks have poor long-term operational stability. In recent years, a series of technological advancements including laser cooling, photon integration, and vacuum technology have made it possible to miniaturize atomic beam clocks. Chip-scale atomic beam clocks are entirely fabricated by advanced MEMS technologies. They combine the high frequency stability of existing microwave atomic beam clocks with the small size and low power consumption of CPT chip atomic clocks, providing excellent comprehensive advantages. However, there have been few reports on chip-scale atomic beam clocks in China so far. Key preparation technologies of the vacuum chamber for chip-scale atomic beam clocks are systematically studied, including microfabrication of beam source cavity, beam drift cavity, and micro collimation channel array, as well as high airtightness packaging of multi-layer micro vacuum chamber structures. Based on optimized deep reactive ion etching technologies, common problems of undercutting and poor process controllability in wet chemical silicon corrosion process have been avoided, and high aspect ratio micro collimation channel arrays with steep sidewalls, smooth surfaces, and precise dimensions are obtained. Through the overall optimization of intermediate electrode extraction technology and anode bonding process, the damage of reverse electric field to the formed bonding interfaces during multi-layer bonding process has been reduced and weakened, and a high-quality five-layer bonding structure of glass and silicon is achieved. This study has laid the basic process foundation for realizing high-frequency stable chip-scale atomic beam clocks and other quantum device systems.

     

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