Control of mechanical properties of micro-material

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1) We measure the thickness of the diffusion layer and the distribution of atoms by Auger electron spectroscopy (AES) and investigate the effect of fabrication process on the diffusion layer. We chose Al and SiOィイD22ィエD2 thin films deposited on a silicon wafer, since SiOィイD22ィエD2 and Al thin films are commonly used for the MEMS. In practice, SiOィイD22ィエD2 thin film is used as a dielectric layer, that is, SiOィイD22ィエD2 is sandwiched between an electrode or wiring and the other material. The SiOィイD22ィエD2 film is also employed as the material for masking or etch-stop layer, and therefore, it works as a structure, that is, substrate for diaphragms or cantilevers. On the other hand, Al is used as an electrode or wiring.In the fabrication process of MEMS, the thin films may be subjected to heat treatment : annealing is carried out to reduce residual stress in the films; when additional material is deposited, the substrate should be heated. In this study, we examine the distribution of atoms th … More in films of Al and SiOィイD22ィエD2 and silicon wafer by AES, and we discuss the effect of heat treatment on the distribution of the atoms.2) We propose a new tensile test method. A prefabricated test substrate on which a thin film is deposited is developed. The concept of our method is as follows. First, on a silicon substrate, gage portion is prefabricated by the surface micro-machining such as a photolithography and wet etching. After fabricating the test substrate, tensile test is performed to measure Young's modulus of the test substrate. Second, the thin film we are concerned is deposited on the prefabricated test substrate. Finally, the tensile test is again carried out. Young's modulus of the thin film can be measured by subtracting the effect of Young's modulus of the prefabricated test substrate. For the purpose of this, we also develop a new tensile test equipment and a test substrate holder. We discuss the viability of this method for measuring the mechanical properties of deposited thin film.3) We make clear the effect of internal mechanical strain on the thin film properties. By controlling the strain of thin film, we can control the electromechanical properties of thin film for MEMS.4) A simulation method for optimizing dynamic of micro-electro-mechanical devices and systems (MEMS) is proposed. A series of equations of electrostatic field, fluid dynamics and deflection of micro-membrane are coupled and solved simultaneously. Since the genetic algorithm is appropriate to reduce the searching space of solution, the genetic algorithm is used to optimize the thickness distribution of a micro-membrane. As an application of the developed method, the thickness distribution of the micro-membrane of a micro air pump is optimized. It is shown that the thickness distribution relates to the distribution of bending strain of the micro-membrane. Less