Study on Simulation and Fabrication of MEMS Solenoid Microinductor with Magnetic Core

Study on Simulation and Fabrication of MEMS Solenoid Microinductor with Magnetic Core
　　Great numbers of separate RF (Radio-Frequency) components in wireless communication systems nowadays have impeded the realization of SOC (System-On-Chip), which is the ultimate goal of miniaturized wireless terminals with high performance and lost cost. The rapid development of MEMS (Micro Electro-Mechanical System) technology in recent years has established itself as a reliable and effective methodology of building micro systems on silicon. As a result, neodymium magnets various RF and magnetic components based on MEMS technology have become wildly-concerned topics to researchers.According to the world’s development of microinductors nowadays, this thesis presents two physical models: a FE (Finite Element) model built with ANSYS as well as a numerical model built based on electromagnetic theory. With these two models, detailed analysis of effects of various factors on performance of microinductor is performed. Microinductor is fabricated by MEMS and tested. Two physical models are compared with experiment, and a possible optimization plan of the inductor is proposed. Key work and conclusions of this thesis are listed as below:(1) Analysis of solenoid microinductor with magnetic core by ANSYS This thesis builds a finite element model of solenoid microinductor with magnetic core based on edge-based 3-dimensional harmonic electromagnetic analysis of ANSYS.
　　Distribution of magnetic field within the microinductor is acquired. And with the calculated result of stored energy and power loss, we further obtain the equivalent inductance and resistance of the magnetic core.(2) A numerical model of solenoid microinductor with magnetic core A numerical model of solenoid microinductor with magnetic core on the basis of classical neodymium magnets  electromagnetic theory is also presented and realized by MatLab programming in this thesis. Agreement of numerical results, ANSYS analysis and experimental measurements is obtained. And within a 4mm by 4mm area, specific analysis is performed in two aspects from material characteristics to geometrical parameters, and in four parts that are coil, magnetic core, insulation material and substrate. With the result acquired, an optimized designing plan is proposed.(3) Fabrication and measurement of solenoid microinductor with magnetic core Solenoid microinductors with NiFe thin film magnetic core are designed and fabricated using MEMS technology. MEMS techniques such as sputtering, lithography, electroplating, dry and wet etching are involved as well as a series of key fabrication technologies such as double-side mask alignment, multilevel metallization, deep photolithography and electroplating, polyimide insulation and fine polishing. Measurements of inductance and quality factor (Q) are carried out 1-10 MHz http://www.chinamagnets.biz/ with Agilent E4991A Impedance/Material Analyzer. According to the obtained data, increase of magnetic core thickness can enhance the inductance of a solenoid microinductor with NiFe magnetic core with sacrificing of Q factor.