适用于极端环境应用的新型氮化铝薄膜谐振式压力传感器研究

Pressure sensing technology is critical to the automobile, aeronautic industry, oil drilling and military application et al, whereas the pressure sensor technology for high temperature harsh environment has always been monopolized by foreign companies, which is the bottle neck to the development of the native large-scale equipment manufacture industry. Two major technologies serve the market, piezoresistive gage and quartz based resonators. The performance degradation of former will occur at the temperature greater than 120℃ due to the electrical leakage at p-n junction that is located sandwiched between strain resistor and substrate; while the latter one will suffer performance degradation at temperature greater than 250℃, due to material phase change induced piezoelectric coefficients loss, respectively. Thus, an AlN thin film resonating type pressure sensor is proposed to be developed in this project for harsh environment application. Initially, the surface acoustic wave (SAW) behaves and equivalent electrical model will be theoretically studied and created; then a multi-physics simulation will be conducted; next, the geometry parameters of the interdigital transducer (IDT) and the pressure sensing diaphragm will be designed accordingly; after that, CMOS compatible fabrication process will be developed; then the measurement data of the first batch devices will be analyzed and evaluated, which is the input information for the second batch optimization design, simulation and fabrication; finally, the stable pressure sensor will be developed for harsh environment (300℃). The target of this project is to lay the foundation of the theory and technology for commercialization of the ruggedized pressure sensors for harsh environment.

压力传感技术对于汽车、航空航天、石油钻井和军事应用等领域有着十分重要的意义，但是适用于高温极端恶劣环境下的压力传感器技术一直被国外公司垄断，严重制约了我国大型装备制造业的发展。目前市面上大多数压力传感器是扩散硅压阻式和石英谐振式，前者在温度高于120℃时，应变电阻与衬底间的p-n结漏电加剧会导致传感器特性严重恶化而失效；后者会在温度高于250℃后材料发生相变从而导致压电特性的退化甚至消失。针对上述情况，本项目拟研发一种适用于极端工作环境的基于氮化铝薄膜技术的谐振式压力传感器。首先对该器件的声表面波和和电学特性进行理论建模，然后对器件进行多物理场仿真，之后对传感器叉指电极和传感薄膜进行设计，开发CMOS兼容工艺进行器件制备，通过分析测试结果对器件进行第二轮优化设计，最后得到适用于高温环境(300℃)性能稳定的压力传感器。该项研究的目标是为极端环境压力传感器的产业化奠定理论和技术基础。

适用于高温极端环境下的压力传感器技术一直被国外公司垄断，严重制约了我国大型装备制造业的发展。针对大多数现有压力传感器在高温极端环境下传感器特性会严重恶化而失效的情况，本课题提出了一种适用于极端工作环境下的基于氮化铝（AlN）薄膜技术的谐振式高温压力传感器结构，建立了谐振式器件的声表面波（SAW）和电学特性理论模型，开展了SAW谐振式器件的多物理场（Multiphysics）仿真研究，优化设计了压力传感器叉指电极和传感薄膜，并开发出兼容CMOS工艺的器件制备工艺，以多物理场（Multiphysics）仿真研究结果作为指导制备得到适用于高温环境(300 ℃)性能稳定的压力传感器，器件压力灵敏度达到-10.28 ppm/psi。课题在完成上述内容的基础上探索了优化器件温度效应的方案，并通过模态差动补偿法实现温度效应的优化，器件温度灵敏度可达到6.66 ppm/℃，为极端环境压力传感器的产业化提供相关理论和技术依据。