Tadao Onzawa

Voltage required to detach an adhered particle by Coulomb interaction for 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 pheno...

Influence of the stiffness of the measurement system on the elastic adhesional contact

An elastic contact theory is described to reveal the effects of the stiffness of the measurement system on the adhesion behavior. The point contact is treated in an elastic continuum limit, taking into account the energy change from the surface to the interface within the contact region. The contact area is determined under Hertzs assumptions. The stiffness of the measurement system is taken into account and the total energy is defined as Etotal = Eelastic + Einterface + Estiffness. The contact radius, the displacement, the force, and the total energy are normalized and their relationships are discussed. In the limit when the stiffness is infinite, our approach conforms to the Johnson-Kendall-Roberts (JKR) theory. The force at the initial contact is discussed as well as the force required to separate samples. The ratio of these forces can be written as a function of only one parameter (κ), which is concerned with the stiffness. A simple asymptotic relation is derived between the force ratio and the param...

Dynamics of micro-object operation considering the adhesive effect under an SEM

This paper proposes a practical micro-object operation based on the dynamic analysis considering the adhesive effect under a scanning electron microscope (SEM). Recently, techniques of arranging micrometer-sized objects with high repeatability under a scanning electron microscope (SEM) are required to construct highly functional micro-devices. Since adhesion is dominant compared to gravity in the micro world, manipulation techniques using a needle-shaped tool by adhesive force are often adopted in basic researches where micro-objects are studied. These techniques, however, have not yet achieved the desired repeatability because many of these have been used just for the empirical reasons. Some even need the process of trial-and-error. Therefore, we analyze micro-object operation theoretically by introducing new physical factors, such as adhesive force and rolling-resistance, into the dynamic system consisting of a sphere, a needle-shaped tool, and a substrate. Through this analysis, we reveal that it is possible to fracture the contact interfaces selectively by controlling tool-loading angle reasonably. Based on the acquired knowledge, we also proposed the practical method of the pick and place operation of a micro-sphere under an SEM.

Instrument for the measurement of adhesion forces in ultrahigh vacuum surface analysis apparatuses

An instrument for direct measurement of the adhesion forces in the ultrahigh vacuum (UHV) chamber of surface analysis apparatus [Auger electron spectroscopy (AES), x‐ray photoelectron spectroscopy, low‐energy electron diffraction, etc.] was developed. It is attachable to any UHV chamber which has a open flange, a manipulator, and a specimen introduction system. It was attached to an AES apparatus (Perkin‐Elmer PHI model 650) and tested. The adhesion force between the Au ball and Si wafers was examined.

Calculation of surface energy and simulation of reconstruction for Si (111) 3×3, 5×5, 7×7, and 9×9 DAS structure

Abstract The Modified Embedded Atom Method (MEAM) is applied to Si(111) surfaces. The surface reconstruction is simulated for N×N DAS structures and surface energies are calculated to be 1571, 1530, 1524, and 1549 mJ/m2 for N=3, 5, 7, and 9, respectively. It is clearly shown that the 7×7 DAS structure is most stable in these N×N DAS structures, and 5×5 is more stable than 9×9. These results correspond to our experimental knowledge. In principle, (M)EAM is a good method to calculate bulk properties. This report suggests that the MEAM is a useful tool also for surface problems.

Analysis of micro-object operation based on the dynamics considering the adhesion under an SEM

Techniques of arranging micrometer-sized objects with high repeatability under a scanning electron microscope (SEM) are required to construct highly functional micro-devices. Since micro-objects tend to adhere to other objects mainly by electrostatic force, the adhesive force is often being considered in basic researches of micro-object manipulation. These techniques, however, still do not achieve the desired repeatability, since many of them are being used just for the empirical effectiveness. Some even include the process of trial-and-error. Thus, we analyze the micro-object operation theoretically by considering the adhesion and rolling-resistance factors in a dynamic system consisting of a sphere, needle-shaped tool, and substrate. Through this analysis, we show that it is possible to control the fracture of the contact interfaces of the system selectively by determining the tool-loading angle appropriately. Based on the analysis, we also propose a practical method for the pick and place operation of a micro-sphere under an SEM.

Effect of the stiffness of the measurement system on adhesion force curves in the elastic continuum limit

An elastic contact theory is described to reveal the effects of the stiffness of the measurement system on the pin-on-disk adhesional contact. The pin is assumed to be elastic and the plane is assumed to be rigid and smooth. The total energy is assumed to be the sum of the following four terms: (i) an elastic energy for the pin, (ii) the specific energy of adhesion in the area of the contact which is expressed as the difference between the surface energies and the interface energy, (iii) the energy for the surface- surface interaction, and (iv) another elastic term for the measurement system such as the cantilever of the atomic force microscope (AFM). The contact area is determined under Hertzs assumptions. A Lennard-Jones type potential is used for the surface-surface interaction. The pressure distribution within the contact region is determined as the superimposition of Hertzs pressure distribution and Boussinesqs distribution. In the limit when the stiffness is infinite, our approach conforms to the...

Development of a modified embedded atom method for bcc transition metals

A new scheme of the modified embedded atom method (MEAM) is developed by modifying the analytic form of the embedding function. The new MEAM parameters for Mo, W, V, Nb, Ta and Fe have been determined by relating them to not only bulk properties but also some non-bulk properties. The new scheme was applied to calculate the elastic stiffness of the crystal, the vacancy formation energy, the lattice stability, the surface energies for low-index crystal faces and the bond length and the binding energy for the dimer. The results give a fairly good agreement with the experimental data.

Modified embedded atom method calculations for reconstructed (110) surfaces of face-centered cubic metals

A modified embedded atom method (MEAM) potential is applied (110) surfaces of several face-centered cubic metals. Surface energies of Au, Pt, and Pb are calculated for the ideal (110) structure, the missing row structure, and the missing column structure, where the last structure is defined in the present paper. The energies calculated for the three structures are discussed with the experimental results obtained from low energy electron diffraction. The MEAM calculations suggest that the missing row structure is most stable for Au and Pt, the ideal structure is most stable for Pb, and the missing column structure is unstable for all cases. These trends show a good agreement with the experimental facts. The position of surface atoms is compared with experimental results. They are in fairly good agreement with each other.

Development of modified embedded atom method for a bcc metal: lithium

A new scheme of modified embedded atom method (MEAM) is proposed in this paper. The analytic form of the embedding function is modified. All the parameters of MEAM have been reset by relating them with bulk properties and some non-bulk properties, for example, the bond length of a dimer and the change of surface interlayer distance. The new scheme has been applied to calculate the elastic stiffness of crystal, the vacancy formation energy and some properties of non-bulk systems such as the surface energies for low index crystal faces, the bond length and the binding energy for a dimer. The results are compared with the experimental data and get a fairly good agreement.