基于CMOS-MEMS单片集成与微悬桥真空缝合的超低气体流速传感器研究

流速传感器广泛应用于环境监测、医疗诊断、工业控制等关系国计民生的重要领域。MEMS技术促进了微型低功耗流速传感器的进步，然而CMOS-MEMS协同设计方法的缺失、微结构减薄制造工艺的复杂性、以及检测极限影响机制的不明确，仍是实现集成化超低气体流速传感器研制的瓶颈问题。本项目提出一种微悬桥真空缝合与接口电路单片集成的量热式流速传感器设计，在简化高灵敏微结构与低噪声电路集成制造的基础上，探明传感器理查森数对其检测极限的影响，实现mm/s级超低气体流速测量。首先，建立气流、热、电耦合的传感器系统级模型，研究微结构与接口电路协同优化的方法；其次，提出传感器真空隔热结构的无光刻单芯片单面减薄加工技术；最后，揭示传感器最小可测流速的影响机制并建立半经验预测模型，探索基于加热温度调控来优化超低检测极限的方法。本项目对拓展单片集成传感器设计与制造方法，促进超低气体流速传感技术的发展具有重要理论与现实意义。

Flow sensors are widely used in environmental monitoring, medical diagnosis, industrial control, and other important fields related to the national economy and people's livelihood. Benefit from the MEMS technology, micro flow sensor with low power design could be realized. However, it is still a great challenge to develop an integrated gas flow sensor with an ultra-low detection limit, due to the lack of a collaborative design method for CMOS-MEMS sensor, the complexity of the microstructure thinning process, and the unrevealed physics behind the detection limit of the flow sensor. This project will propose a monolithically integrated CMOS-MEMS calorimetric flow sensor with the vacuum sealing of microbridges. After the simplification of the fabrication process for the integration of high sensitivity microstructures and low-noise interface circuits, the influence of the sensor's Richardson number on the sensor detection limit is explored, and those research approaches will help the sensor achieve the capability for the measurement of mm/s level ultra-low gas flow. First, a system-level sensor model that is fully coupled with the gas flow, thermal, and electrical transduction process will be established, while the collaborative optimization for the microstructure size and interface circuit parameters effect on the flow sensor performance will be investigated. Second, a simplified Post-CMOS fabrication technology for the single-chip single-sided releasing and thinning of the MEMS structure will be proposed without the leverage of photolithographic. Finally, the characterization of sensor performance will be carried out, while the factors that affect the ultra-low flow velocity measurement will be revealed, and a semi-empirical model for the prediction of the minimum detectable flow velocity (MDFV) of the flow sensor will be established. Accordingly, a new method to optimize the ultra-low detection limit of the CMOS-MEMS flow sensor through the manipulation of heating temperature will be proposed. This project has important theoretical and practical significance for the development of design and microfabrication methods for the monolithically integrated flow sensor and the promotion of ultra-low gas measurement sensor technology.