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[en] Fabrication techniques for devices having dimensions of about a micrometer are presented. A versatile low cost photolithographic microscope projection technique and chemical etching are used as part of the fabrication process. The whole procedure is proposed as an alternative to razor blade or diamond scratching techniques in laboratory research at low temperatures. A detailed description of the equipment and methods is given. Specific examples of one material devices and two material devices are described in connection with physical problems of recent interest. The broad field of application of the techniques shown make them appropriate for creating structures that might have defined and reproducible forms from millimeter dimensions down to 0.5 μm
[en] We present a material removal rate model for MRF of optical glasses using nanodiamond MR fluid. The new model incorporates terms for drag force, polishing particle properties, chemical durability and glass composition into an existing model that contains only terms for the glass mechanical properties. Experimental results for six optical glasses are given that support this model
[en] During the Chemical mechanical planarization (CMP), the pad conditioning process can affect the pad surface characteristics. Among many CMP process parameters, the improper applied load on the conditioner arm may have adverse effects on the polyurethane pad. In this work, we evaluated the pad surface properties under the various conditioner arm applied during pad conditioning process. The conditioning pads were evaluated for surface topography, surface roughness parameters such as Rt and Rvk and Material removal rate (MRR) and within-wafer non-uniformity after wafer polishing. We observed that, the pad asperities were collapsed in the direction of conditioner rotation and blocks the pad pores applied conditioner load. The Rvk value and MRR were founded to be in relation with 4 > 1 > 7 kgF conditioner load. Hence, this study shows that, 4 kgF applied load by conditioner is most suitable for the pad conditioning during CMP
[en] The theoretical basis is developed for a technique to fabricate nonaxisymmetric mirrors. Stresses are applied to a mirror blank that would have the effect of elastically deforming a desired surface into a sphere. A sphere is then polished into the blank, and upon release of the applied stress, the sperical surface deforms into the desired one. The method can be applied iteratively, so arbitrary accuracy should be possible. Calculations of the stresses and deformations are carried out in detail for an off-axis section of a paraboloid. For a very general class of surfaces, it is sufficient to only impose appropriate stresses at the edge of the blank plus a uniform pressure on the back
[en] According to Preston [J. Soc. Glass Technol. 11, 214 (1927)], the wear on a glass point in the polishing process is proportional to the work given by frictional force between glass and tool. He supposed that the frictional coefficient is a constant value. To verify this hypothesis, we measured the dragging forces applied to a tool as a function of the relative speed between a rotating glass and the tool center. To reproduce these experimental results, it was necessary to propose a new model, for which the frictional coefficient has a Gaussian dependence with relative speed. Therefore the wearing Preston equation has to be modified in order to include the frictional coefficient as a function of the relative speed
[en] Magnetorheological finishing (MRF) is a computer-controlled deterministic polishing technique that is widely used in the production of high-quality optics. In order to overcome the defects of existing MRF processes that are unable to achieve concave surfaces with small radius of curvature, a configuration method of a novel structured MRF machine tool using small ball-end permanent-magnet polishing head is proposed in this paper. The preliminary design focuses on the structural configuration of the machine, which includes the machine body, motion units and accessory equipment, and so on. Structural deformation and fabrication accuracy of the machine are analyzed theoretically, in which the reasonable structure sizes, manufacturing errors and assembly errors of main structural components are given for configuration optimization. Based on the theoretical analysis, a four-axes linkage MRF machine tool is developed. Preliminary experiments of spot polishing are carried out and the results indicate that the proposed MRF process can achieve stable polishing area which meets requirement of deterministic polishing. A typical small-bore complex component is polished on the developed device and fine surface quality is obtained with sphericity of the finished spherical surfaces 1.3 μm and surface roughness Ra less than 0.018 μm.
[en] Dielectric barrier Discharge(DBD) is an easily obtainable plasma source at atmospheric pressure. And the operating frequency is reached to RF from AC. In this study, we try to etch a Si wafer by using DBD. Atmospheric pressure plasma was generated using the plate to plate DBD with the power electrodes of the planar copper plate and silver coated stripe. The size of electrode was 89mm x 100mm. We compared the effect of the electrode's shapes on the etching of Si-wafer. And for the large surface processing, remote type DBD is used Discharge character of the DBD is investigated by measuring a power absorbtion as a function of frequency. We obtain the optimum frequency of around 2.5 kHz for power absorption. We change the several factors of experiments like O2(from 0 to 60sccm) flow rate, N2(0 to 2slm) flow rate, and frequency(1000Hz to 3000Hz) with each electrode configuration. In remote type, we change the distance from the DBD to sample and change the O2 from 0 to 60sccm, N2 from 0 to 3 l/min and CF4 from 50 to 300sccm. Finally, change the number of electrode (Silver paste), and measured the power and etching rate. In lattice shape etching was about 1.35μm/min, and in remote type, we get about 700nm/min
[en] Solid-state nanopores have been widely used as building blocks for nanofluidic devices and circuits from both fundamental and application aspects. In this review, we sketch the recent research progress in our group on the fabrication and application of single nanopores in PET membrane by track-etching method. The asymmetric ion transport properties in the conical nanopore are intensively studied both experimentally and theoretically. Based on the understanding of the particular ion transport behavior on nano-scale, some applications are present, including the pressure-driven streaming current and synthetic nanopore-DNA system.
[en] A new parameter of sputtering, the erosion energy efficiency, is defined as the ratio of the theoretical energy required to eject atoms to the experimental energy. This efficiency eta (E) is shown to be proportional to the ratio of the sputtering yield Y(E) to the energy E and, even under optimum conditions never exceeds approximately 10%. The relationship of this efficiency to the broadening process occurring during sputter profiling resulting from recoil atomic motion and mixing is examined. It is shown that the ion energy conditions employed in both technological etching and sputter profiling systems are near optimum for energy utilization and profile broadening minimization. (author)