Dual-Layer Silicon Nitride Cantilever Beam Optical MEMS Accelerometer

本研究旨在开发一款高精度光MEMS加速度计，在地震监测中能够检测微弱的地震波动和震动，有助于更早地识别地震活动并做出预警。首先，采用SolidWorks软件对加速度计进行三维建模。随后，通过COMSOL有限元仿真对器件进行灵敏度仿真，仿真结果显示器件灵敏度为359.6 nm/g。采用MEMS工艺完成加速度计悬臂梁质量块结构制造，并通过环氧树脂胶合形成法布里珀罗腔结构。再利用波长追踪法对器件进行灵敏度测试。将传感器沿重力场方向偏转角度，利用不同重力场分量对器件灵敏度进行标定。测试表明，器件灵敏度达到358.5 nm/g，与仿真值接近，并且在测试范围内加速度计非线性度误差为0.58%。此外，理论的机械热噪声为397 ng/√Hz。因此，文章建立了MEMS光加速度计的设计、仿真、制造及测试方法全流程，为高精度地震监测提供了有力技术保障，并为后续相关领域的深入研究与应用奠定了坚实基础。The aim of this study is to develop a high-precision optical MEMS accelerometer, which is capable of detecting weak seismic fluctuations and vibrations in seismic monitoring and helps to identify seismic activities earlier and make early warnings. Firstly, the accelerometer was modeled in 3D using SolidWorks software. Subsequently, the sensitivity of the device was simulated using COMSOL finite element simulation. The simulation results show that the sensitivity of the device is 359.6 nm/g. The fabrication of the accelerometer cantilever beam mass block structure is completed by using the MEMS process, and the Fabry Perot cavity structure is formed by epoxy resin gluing. The sensitivity of the device was tested using the wavelength tracking method. The sensor was deflected at an angle along the direction of the gravity field, and the device sensitivity was calibrated using different gravity field components. The tests show that the device sensitivity reaches 358.5 nm/g, which is close to the simulated value, and the accelerometer nonlinearity error is 0.58% over the tested range. In addition, the theoretical mechanical thermal noise is 397 ng/√Hz. Therefore, this paper establishes the whole process of MEMS optical accelerometer design, simulation, fabrication, and testing method, which provides a strong technical guarantee for high-precision seismic monitoring and lays a solid foundation for subsequent in-depth research and application in related fields.