Fabrication On Key Technology Of Electrostatic MEMS Capacitor With High Aspect Ratio Based On Silicon Structure

Micro-energy with micro-small, long life, high reliability, high performance is to achieveone of the development trend and important core technology for the devices withinformationization, intelligent, integrated and miniature in the energy storage system. Atpresent, however, in the intelligent system, the key problems of intelligent micro-energy arethat the more function of micro-devices have, the less of volume, as well as equipping withthe requirements for power with more powerful, larger surface area, lower cost, especiallythere are some problems which the power has less energy density and worse environmentaladaptability when micro-machining (MEMS) would be applied. In order to solve theseproblems, many new technology and structure design are studied extensively. miniaturecapacitor based on MEMS technology not only has the ultra-small features of MEMStechnology, but has the advantages of light weight, high energy density, strong environmentaladaptability and less pollution, which provide the basis and theoretical guidance in the filedof micro-energy storage system, network system, transportation and other fields.In this paper, the energy storage mechanism of MEMS capacitor is studied, and thestructure and the electrical properties of the device are simulated by using ANSYS.12andCOMSOL Mutiphysics4.0a in order to get rational dimension and parameters of process fordevice. Therefore, in the MEMS process, the metal film is selected to be mask material foretching because of its high ratio of selecting, then the vertical micro-trench structures withhigh-aspect-ratio, which are formed the column type, would be fabricated by deep reactive ionetching technology, as well as the dielectric material with high reliability, uniform and high-kis deposited by atomic layer deposition technology. In order to reduce roughness of deviceinternal surface, the way from oxidation to etching would be repeating utilized to twice.Finally, the MEMS capacitors of electrostatic based on silicon with different sizes areproduced. The results show that: compared with the structure of which width is5μm and8μm, respectively, the sidewall of micro-trench structure with10μm has smaller roughness andhigher verticality, which will provide better reliability for process of MEMS capacitors in the future. Besides, in the process of etching, the passivation gas would be changed. It can beexplained that the O2in the passivation process is adding another protective layer for profileand prevent the micro-trench from lateral etching.The simple and effective testing of semiconductor parameter test system platform ofMEMS capacitors is simply designed. HP4284A and temperature control instrument areselected to test the electronic properties and temperature characteristics of MEMS capacitors.The results show that: the capacitances are gradually increasing with the development ofvoltage, especially the MEMS capacitor with10μm wide trench respects larger capacitanceand lower leakage than others, besides, it has much higher working temperature and betterenvironmental adaptability than others.