Design And Implementation Of The Oven-Controlled MEMS Resonator

The resonator is the core device that generates time-frequency signals(referred to as "time-frequency signals").It is the reference for applications such as sensing,positioning,and navigation.It is also the "heart" of all electronic systems.The stability of its output frequency signals affects the overall performance of the system.With the in-depth deployment of strategic technological devices such as Io T terminals,wireless sensor nodes,and smart drones,traditional quartz resonators that are bulky and difficult to integrate have become one of the bottlenecks that limit system miniaturization and performance.Silicon-based MEMS(Micro Electro-mechanical System)resonators are manufactured based on semiconductor technology.Compared with traditional quartz resonators,the size has been reduced by more than ten times,and it can be compatible with CMOS(Complementary Metal Oxide Semiconductor)chips.Therefore,it is expected to give relevant fields Bring disruptive innovation.However,the main disadvantage of MEMS resonators is that the resonant frequency will be affected by the external temperature,and its stability is lower than that of quartz resonators.The stability of resonators limits the accuracy of applications such as sensing,positioning,and navigation.Therefore,research on how to improve the stability of MEMS resonators is a key issue to be solved.The development of high-stability MEMS resonators has important strategic and technological significance.In order to solve the above problems,this dissertation takes silicon-based piezoelectric(Thin-film Piezoelectric-on-Silicon,TPo S)MEMS resonator as the main object,studies the design method of the device structure and constant temperature system,and develops a high stability constant temperature MEMS Resonator(Oven-controlled MEMS resonator,OCMR).First of all,this dissertation introduces the research background and current status of MEMS resonators,summarizes the main performance indicators and development directions of MEMS resonators,and summarizes the methods for improving the performance of MEMS resonators.The working principle,equivalent model,eigenmodes,energy loss mechanism and basic structure of the TPo S MEMS resonator are described.The processing and testing method of TPo S resonator based on Al N(Aluminum Nitride)thin film is proposed.Secondly,a new three-cantilever structure resonator chip is proposed,and the acoustic reflection cavity and partial coating coverage method are optimized at the same time,which avoids frequency strays,reduces anchor loss and coating loss,and improves the quality factor of MEMS resonators.The process flow is proposed and the TPo S resonator is manufactured,and the performance of the MEMS resonator is verified by physical testing.Again,a PID(Proportional Integral Derivative)-PWM(Pulse Width Modulation)controlled constant temperature micro-hot plate with a square root link is proposed.On this basis,it is proposed to introduce airgel to insulate the bottom of the chip to reduce power consumption.The process flow is designed and a system prototype is manufactured,and the performance of the chip is verified through physical testing.The proposed method effectively suppresses the temperature drift of the MEMS resonator.Then,a constant temperature MEMS resonator based on PSO(Particle Swarm Optimization,PSO)-IMC(Internal Model Control,IMC)tuning method is proposed.The inner layer control system is formed by using the top electrode as heating and sensor.The above-mentioned constant temperature micro-hot plate is used as the outer layer control system.A two-level control system was combined and a system prototype was fabricated.The test results show that the proposed method further improves the temperature stability.Finally,a frequency tuning method based on electrostatic traction and fractional-order PLL is proposed,and a simulation model is established to verify the effectiveness of the proposed method.In addition,a dedicated sapphire MEMS probe card based on dual electrical tracks is proposed to explore the feasibility of batch testing of MEMS resonators.Design,manufacture and verify the performance of the dedicated probe card.Provide a feasible reference for batch manufacturing and testing of MEMS resonators.In summary,this dissertation has carried out the development work on the constant temperature MEMS resonator.Three cantilevers,acoustic reflection grid structure and coating optimization are proposed to optimize the design of TPo S resonator.On this basis,a structure based on micro-hot plate,double-stage isolation,PSO-IMC,square root link PID-PWM control method is proposed to improve the stability of MEMS resonator.As an extension,the feasibility of electrostatic traction,fractional-order PLL and MEMS probe card for mass manufacturing of MEMS resonators is explored.