The Electric Field Sensor Based On SOI

Recently, the slogan that to develop the strong smart grid whose core technology isto use the sensor monitoring the operation of the critical equipments in real-time hasbeen promote by State Grid Corporation of China. Through data analysis and datamining(DM), the power system can be optimized. However, corona discharge, flashoverand electromagnetic environment are electric field problems, so it is necessary to detectthe electric field online. Compared to the traditional optical electric field sensor basedon electrostrictive effect, the micro electric field sensor based on the principle of chargeinduction has the advantage as: low cost, low power consumption and small size, whichcan satisfy the needs of the power system. In this paper, a miniature electric filed sensor,for smart grid, based on SOI structure has been designed and simulated in electrostaticfield and power frequency AC electric field. The manufacturing technology of MEMShas been studied systematically.In the design of the sensor structure. This thesis puts forward an innovative methodto achieve the lateral electric field sensor with a new sensing structure. The peripheralcircuit is used to hold the potential of the shielding electrode and collect the chargesinduced by shielding electrode, which double the resolution of the electric field. Byusing ANSOFT MAXWELL simulation software to simulate the structure of the sensingpart and taking the max change rate of charges induced in a single cycle as the objectivefunction, we can determine the size of the sensing electrodes. By using ANSYS finiteelement analysis software to simulate the actuator, the maximum output distance withlimited input voltage and the parameters of the actuator have been obtained. Then, theanalysis of mode of the entire structure is carried out and the size of the spring isadjusted to obtain a appropriate resonant frequency. Through the simulation andoptimization, the output current can reach4.8×10-10A when the strength of electricfield is100V/m. On the condition that the DC drive voltage equals±1V, thedriven displacement reaches17.8μm. The frequency of the first order modal is3393.9Hz, which meets the require that the highest frequency cannot exceed4kHz in heat-driven structure.According all the theoretical analysis and experiments above, the4mm×4mm structure is designed, as well as the detailed fabrication procedure and lithographymasks. Finally, the device is manufactured. In order to achieve the mechanical andelectrical interconnection between the microstructures, related bonding technologieshave been studied and the Au-Si eutectic bonding is chosen by us. The process of Au-Sieutectic bonding has been researched, the void formation mechanism and the bondingparameters have been discovered. During the manufacture, we find that the Au-Sieutectic bonding play a decisive role in the entire process. Therefore, the mechanism ofvoid formation has been fully studied and we propose a mathematical model to predictthis phenomenon, which provide the theoretical and experimental bases for subsequentmanufacturing.