Recently, microelectromechanical systems (MEMS) are installed in most automobiles and portable electronic devices like as smartphone. MEMS devices have evolved dramatically by vacuum technologies. Early MEMS devices were fabricated by anisotropic wet etching process. Current MEMS devices are fabricated by vacuum processes based on semiconductor fabrication technologies. Vacuum technologies are also used for a control of dynamic characteristics of MEMS devices in hermetically--sealed package. In this paper, we report the trend of MEMS devices and the role of vacuum technologies, for pressure sensors, accelerometers, mirror devices and field emission devices, as examples.

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  MEMS (Micro Electro Mechanical Systems) are an important technological field that is expected as a small-sized, energy-saving and high-performance key device. However, since development of MEMS requires considerable expenses and time, reduction of the testing expense, shortening of the development period and improvement of the yield ratio are expected with use of a simulator. Although leading MEMS foundries have begun to utilize simulators made abroad, purely domestic “Computer Aided Engineering System for Micro Electro-Mechanical Systems (MemsONE)” developed in a national project have come into use recently.

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  We deposited BaTiO₃ (BTO) thin films on Pt/Ti/SiO₂ substrates at the substrate temperatures (T_sub) of 300 and 500℃ in RF magnetron sputtering method, changing sputtering gas flow ratios of oxygen to total gas (R[O₂]) and the distances between substrates and targets (d_T-S). From the results, we found that the (001)-oriented BTO films were obtained at the low T_sub of 300℃ using the d_T-S of 30 mm. The orientation of the BTO films deposited at 300℃ are dependent on the d_T-S from 30 mm to 50 mm. The deposition rates of the BTO films at the d_T-S of 30 mm were larger than those at 40 and 50 mm. Electrical resistance perpendicular to the substrate in the film deposited at 500℃ was higher than that at 300℃. The P_r and E_c of the film at 500℃ were estimated to be 3.4 μC/cm² and 63.5 kV/cm, respectively. (001)-oriented BTO films crystallized at low T_sub of 300℃ is obtained by short d_T-S, since the short d_T-S may supply more materials to the substrates in the plasma where there are many active particles of constituent elements in BTO.

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  Since materials of plastomer materials of synthetic resin have a large outgassing rate than metals, they are not so suitable for use as uhv components. However, some of the plastomers are often installed in vacuum system, where their low electrical- and thermal-conductivity are required. The outgassing rates were measured for bulk samples of FRP, PEEK and polyimide, and for thin sheets of PET (Aluminum deposited PET film of 9 μm thick.) and polyimide. The outgassing rate is decreased in a manner of t^−1/2, indicating diffusion process of absorbed gas molecules from bulk. The rate of sheet, being after several tens hour pumping, shows rapid decrease. The effect of bake-out degassing in vacuum is also examined for bulk plastomers.

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  Dissociative adsorption process of O₂ molecule on Pt(001) surface are explored using quantum dynamical calculations based on coupled-channel method. The explored adsorption sites are the direct dissociative adsorption channels, where the molecularly adsorption or precursor state for O₂ sticking are absent, with certain amount of activation barrier. We find that the dissociative sticking probability of O₂ depicts the sigmoidal (S-shaped) curve in all cases which is a manifestation of the tunneling effect. Moreover, the sticking curve is sensitively dependent on the shape of the activation barrier which affects the width of the transition region. Finally, the tunneling effect can be clearly acknowledged from the wave function of O₂.

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  Trajectories of fast (0.55 MeV) protons impinging under planar surface channeling conditions with an angle of incidence of several mrad are calculated on KBr(001) surfaces decorated by electron stimulated desorption (ESD). Two-dimensional angular distributions of protons scattered on the surface are obtained. In order to calculate trajectories, a computational technique is needed to form a set of morphologies of the surfaces according to the electron fluence. In our method, an assumption is made that the topmost atoms on the low coordinate sites are easily emitted by the ESD processes. By choosing parameters introduced in the method, the oscillatory behavior of the desorption yields demonstrated by other groups is reproduced. The resulting peak intensity of the reflected protons from the trajectory on the ensemble of surfaces with varying electron fluence oscillates as the electron fluence increases. Corresponding angular distributions of reflected protons have been measured on the electron irradiated KBr(001) surfaces, and a similar oscillation can be seen on the scattered yields with weak amplitudes.

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