Papers by Keyword: Imprint

Abstract: The aim of the paper is to present developed methodology for evaluation of mechanical properties using nondestructive (NDT) methods. The final methodology will focus on evaluating the mechanical properties of the heterogeneous weld structure. The mechanical properties are determined by conducting NDT instrumented Vickers hardness test. The developed methodology for the basic mechanical properties determining is based on the inverse FEM modeling of instrumented hardness test and the indentation curve and the measured surface imprint are the output of indentation. The outputs from the experimental hardness test (the corresponding values from indentation curve and measured surface) are not always corresponding. These differences affect the accuracy of the developed methodology, because it is achieved of the basic material mechanical properties by comparing the outputs of the experimental instrumented hardness test and modeled hardness test using FEM.

Abstract: Silica glass is known to exhibit permanent changes in density under very high pressures. These changes may reach 21%. The sharp indentation test develops pressures underneath the indenter that trigger densification. Recently, we have proposed a constitutive modeling of the pressure-induced process accounting for its salient features: densification threshold, hardening, saturation of densifica- tion and permanent increase in elastic moduli. We examine in this paper the possibility that densi- fication could be the only mechanism for creating an imprint by indentation. We consider different models with growing complexity that we implement in a finite element software. Results indicate that the combination of shear and pressure as a driving force to densification may account for the mechanical response of the indentation test as well as the presence of densified zone underneath the imprint.

Abstract: We have fabricated X-ray diffraction gratings for X-ray phase imaging using X-ray Talbot interferometer. In this paper, we propose the new low cost fabrication process using Si mold of Si dry etching and nano-imprint techniques. Si dry etching makes it possible to fabricate high aspect ratio rectangular microstructures. Therefore, this technique is expected to fabricate high precision grating pattern. In this paper, we propose the new low cost fabrication processes using Si mold of ICP-RIE and nano-imprint techniques. And, in order to form transparence imprint mold, we used thermal oxidation of Si mold. These demonstrations of thermal oxidation are promising method for high precision transparence imprint mold with low cost, and realized low cost optical device such as diffraction gratings.

Abstract: The structural origin of imprint in Pb(Zr,Ti)O₃ (PZT) ferroelectric thin films derived by chemical solution deposition with Pt top and bottom electrodes was studied by in-situ high-resolution X-ray specular reflectivity of synchrotron radiation. Global structural parameters of density, thickness, and surface or interface roughness of each component layer in the thin film sample were obtained. No generation of interfacial layers with a different electron density from PZT and no interface roughening were observed at the interfaces of PZT and Pt during imprint. Thus, the results suggest that the imprint effect is more likely a bulk or electronic defects-related phenomenon.

Abstract: This paper presents an approach to fabricate nanoscale gratings by direct imprint on silicon substrate. Imprint conditions that affect the transcription accuracy, such as imprint temperature and pressure, are discussed, and the profile of the imprinted 80nm width gratings with a 250 nm pitch is checked by SEM. High fidelity and fine uniformity demonstrate that nanoimprint is an economical and efficient method to fabricate nanoscale gratings.

Abstract: This study presents an innovative imprinting method to fabricate IC devices by micro-punch process. Normally, imprinting method is used to imprint plastic materials such as photoresist and polymeric materials. In this study, imprinting process is applied to micro-punch metallic materials directly for IC devices. Fabrications of IC devices with high aspect ratio structures ranging from micrometer to sub-micrometer are described. In this study, to keep the production costs as low as possible, a complete micro-punching process is applied to replicate IC devices. A combination of lithography, extra-hard alloy nickel cobalt (Ni/Co) electroplating process (as a metal imprint mold for punch) and chemical mechanic polishing (CMP) process is used to flat the extra-hard alloy micro-punch head. It is worth noticing that the Ni-Co electroplating process with hardness over Hardness of Vicker (Hv) 560 is developed. With such hardness, it can stand the high pressure and abrasivness to confine the accuracy during micro-punching process. With regard to the electroplating process, Ni-Co is deposited and covered on the photoresist template uniformly by electroplating. The Ni/Co mold is served as master for micro-punching process to replicate the pattern onto polyimide (PI) or copper sheets. Finally, the experimental results are measured and characterized.