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Relative humidity dependence on electrostatic pick-and-place operation is investigated to improve the reliability of micro-manipulation. The manipulation system consists of three elements: a conductive probe as a manipulator, a conductive plate as a substrate, and a dielectric particle as the target object for manipulation. To pick up/place the particle, a rectangular pulse voltage is applied to the probe. Capillary condensation at the particle-plate interface is theoretically considered to evaluate a detachment voltage (the voltage to detach the particle). Surface conductivity of the particle is theoretically considered to evaluate a detachment time (the time for detaching the particle). Experiments are conducted in relative humidities of 30%, 40%, 50%, and 60% by using a soda-lime glass particle with a diameter of 30 μm. It is clarified that the detachment voltage increases and the detachment time decreases by increasing relative humidity. The particle can be successfully picked up/placed by clarifying the effect of relative humidity on the detachment voltage and the detachment time. This knowledge, relative humidity dependence on electrostatic pick-and-place operation, will contribute to micro-fabrication technology by enhancing adaptability in various atmospheric conditions.Relative humidity dependence on electrostatic pick-and-place operation is investigated to improve the reliability of micro-manipulation. The manipulation system consists of three elements: a conductive probe as a manipulator, a conductive plate as a substrate, and a dielectric particle as the target object for manipulation. To pick up/place the particle, a rectangular pulse voltage is applied to the probe. Capillary condensation at the particle-plate interface is theoretically considered to evaluate a detachment voltage (the voltage to detach the particle). Surface conductivity of the particle is theoretically considered to evaluate a detachment time (the time for detaching the particle). Experiments are conducted in relative humidities of 30%, 40%, 50%, and 60% by using a soda-lime glass particle with a diameter of 30 μm. It is clarified that the detachment voltage increases and the detachment time decreases by increasing relative humidity. The particle can be successfully picked up/placed by clarifying ...

During micromanipulation, the influence of gravitational force becomes extremely small. The adhesional force is more significant for smaller objects. An adhered object can be detached by electrostatic interaction. In our earlier study, the electrostatic force generated by an applied voltage and the voltage required for detachment have been theoretically analyzed using the boundary element method (BEM). The system consists of a manipulation probe, a spherical microparticle, and a substrate plate. These objects are all conductive. In this study, the voltage for detachment of a microparticle with a 30-μm diameter is experimentally clarified, and is revealed to be in good agreement with the voltage predicted by BEM analysis. In addition, phenomena other than detachment are discussed based on observations through an optical video microscope. These results provide us with knowledge about the strategy for reliable electrostatic micromanipulation.

In this paper, the kinematics of mechanical and adhesional micromanipulation using a needle-shaped tool under a scanning electron microscope is analyzed. A mode diagram is derived to indicate the possible micro-object behavior for the specified operational conditions. Based on the diagram, a reasonable method for pick and place operation is proposed. The keys to successful analysis are to introduce adhesional and rolling-resistance factors into the kinematic system consisting of a sphere, a needle-shaped tool, and a substrate, and to consider the time dependence of these factors due to the electron-beam (EB) irradiation. Adhesional force and the lower limit of maximum rolling resistance are evaluated quantitatively in theoretical and experimental ways. This analysis shows that it is possible to control the fracture of either the tool-sphere or substrate-sphere interface of the system selectively by the tool-loading angle and that such a selective fracture of the interfaces enables reliable pick or place operation even under EB irradiation. Although the conventional micromanipulation was not repeatable because the technique was based on an empirically effective method, this analysis should provide us with a guideline to reliable micromanipulation.

An adhered particle can be detached by Coulomb interaction. The voltage required for detachment for micromanipulation is theoretically analyzed by employment of a boundary element method. The system consists of a manipulating probe, a spherical particle, and a substrate plate, all of these objects being conductive. The manipulator and the substrate are cylindrical, and axial symmetry is assumed. Although a numerical method is used to solve the equations, all parameters are normalized. The effect of the shape parameters on the Coulomb force is systematically calculated. The force is independent of system size and depends on the relative shape of the system. The force is proportional to the applied voltage raised to the second power. The force generated by the Coulomb interaction is compared with the adhesion force deduced from the Johnson–Kendall–Roberts theory, and the voltage required for detachment is clearly expressed. The possibilities and limitations of micromanipulation using both the adhesion phenomenon and Coulomb interaction are theoretically discussed.

The scintillation properties of a hydrothermal method grown zinc oxide (ZnO) crystal are evaluated for extreme ultraviolet (EUV) laser excitation at 13.9nm wavelength. The exciton emission lifetime at around 380nm is determined to be 1.1ns, almost identical to ultraviolet laser excitation cases. This fast response time is sufficiently short for characterizing EUV lithography light sources having a few nanoseconds duration. The availability of large size ZnO crystal up to 3in. is quite attractive for future lithography and imaging applications.