Stress Identification And Verification Of Silicon Microresonant Accelerometer Package

Packaging is an extremely important link in the manufacture of MEMS devices,and plays a crucial role in the stability,reliability and cost of MEMS devices.Packaging stress is one of the main causes of performance degradation of MEMS devices.For high-precision MEMS devices such as silicon micro-resonant accelerometers,low-stress packaging technology is one of the key technologies that must be overcome.Accurate identification of packaging stress will provide necessary guidance for low-stress packaging technology,which is very important.important practical significance.This paper studies the device-level packaging stress of silicon micro-resonant accelerometers.The main contents of the research include:Firstly,the basic working principle of the silicon micro-resonant accelerometer is studied,and the temperature characteristics of the silicon micro-resonant accelerometer are studied.It is clear that the residual stress is the main factor affecting the frequency output of the device.Secondly,the multi-layer stress of the silicon micro-resonant accelerometer is studied,and a theoretical model for multi-layer stress analysis is established.A device-level package stress identification method based on the resonator force-frequency principle is proposed.The influence of the stress sensitivity of the resonator and the beam width error on the identification accuracy is analyzed.Then,for the silicon micro-resonant accelerometer developed by our research group,the accurate modeling method of the three-dimensional simulation model of the accelerometer chip and package structure is studied.The 3D optical profiler was used to obtain the surface topography of the chip before and after packaging,and the 3D simulation model was corrected according to the experimental results.Using the optimized simulation model,the main process of the accelerometer device-level packaging was simulated,and the stress generated by the device-level packaging was characterized by the accelerometer anchor point displacement,and the device-level packaging stress identification theory based on the resonator force-frequency principle was verified.Finally,based on the resonator force-frequency principle,a device-level package stress identification process for silicon micro-resonant accelerometers is proposed.For the silicon micro-resonant accelerometer independently developed by our research group,the package stress identification experiment was completed.Through the scaling factor,the actual beam width of the accelerometer is obtained,and combined with the frequency difference before and after packaging,the magnitude of the device-level packaging stress is identified.Finally,a real-time identification method for device-level packaging stress of silicon micro-resonant accelerometers is formed,which meets the requirements of rapid batch stress identification and lays a foundation for the subsequent packaging optimization of MEMS devices.