森田 昇

Mask-free and rapid patterning of fused quartz surface is useful for various applications, such as rapid prototyping of optical elements and UV nanoimprint molds. We examined the fabrication of patterned quartz for such applications by ion-bombardment-enhanced etching using buffered hydrofluoric acid as the etching solution.

Novel cutting tools that had either microscale or nanoscale textures on their surfaces were developed in this study. Texturing microscale or nanoscale features on a solid surface allowed us to control the tribological characteristics of the tool. In this report, diamond like carbon (DLC) coated tools with the texture were developed using a femtosecond laser and subsequent DLC coating methods. By applying DLC coating, the effects of the texture were evaluated without adhesion of a work material due to its low adhesion rate and application of the texture to coated tools can also be investigated. Turning experiments of aluminum alloy were performed under the various cutting conditions. It was found that the wet condition was suitable for the developed tool and the further decrease in cutting forces were observed when the texture was applied to the DLC coated tools. The tendency of the direction of the texture was similar to that of the noncoated textured tools, which indicates that the difference in the effect of the texture was decided not only by the adhesion characteristics of the work material but also by other factors. The effects of the texture were observed even at the low cutting speed. These results indicate that the textured tool is applicable for the DLC coated tool.

This study aims to fabricate three-dimensional microstructures on a silicon surface using focused ion beam (FIB) irradiation and wet chemical etching. A silicon surface irradiated with FIB withstands etching in KOH, and consequently protruding structures can be fabricated on the irradiated area. Three-dimensional fabrication is possible by taking advantage of the change in the etch stop effect due to irradiation conditions. To fabricate higher structures efficiently, height dependences on various fabrication conditions were investigated. As a result, the height of the structures can be controlled by ion dose, in spite of the higher dose condition. A hard-to-etch mask was formed by preventing the channeling effect. Higher structures were fabricated with shorter etch time at the high-temperature conditions. Etching selectivity increased at high dose and low etchant concentration. These results enable us to fabricate higher structures efficiently.

A small precision nanomachining and measurement system was developed with a targeted machining resolution on the order of scales ranging from submicrons to several nanometers. The system was comprised of two machining functions, scratch machining and milling, and one measurement function. The scratch machining function was based on a fnctional force microscope mechanism with a closed-loop numerical control (NC) to control the depth of the cut. A stiff cantilever was used for the scratch-machining function to permit nanomachining of hard and brittle materials such as silicon. The milling function used an original miniature tool that had a very small diamond mounted on it that permitted micromachining. The measurement function incorporated into this system used the same mechanism as the scratch-machining function, and provided a degree of precision almost equal to that of atomic force microscopy. After constructing this system, we performed various machining tests with it to confirm that the integrated NC closed-loop control function performed correctly.

In various fields of nanotechnology, the importance of nanoscale three-dimensional (3D) structures is increasing. In order to develop an efficient process to fabricate nanoscale 3D structures, we have applied highly charged ion (HCI) beams to the ion-beam lithography (IBL) technique. Ar-ion beams with various charge states (1+ to 9+) were applied to fabricate spin on glass (SOG) and Si by means of the IBL technique. The Ar ions were prepared by a facility built at Kochi University of Technology, which includes an electron cyclotron resonance ion source (NANOGAN, 10 GHz). IBL fabrication was performed as a function of not only the charge state but also the energy and the dose of Ar ions. The present results show that the application of an Ar9+ beam reduces the etching time for SOG and enhances the etching depth compared with those observed with Ar ions in lower charged states. Considering the high-energy deposition of HCI at a surface, the former phenomena can be understood consistently. Also, the latter phenomena can be understood based on anomalously deep structural changes, which are remarkable for glasses. Furthermore, it has also been shown that the etching depth can be easily controlled with the kinetic energy of the Ar ions. These results show the possibilities of the IBL technique with HCI beams in the field of nanoscale 3D fabrication. ? 2008 American Institute of Physics.

The ion beam lithography (IBL) method is one of the promising techniques that can fabricate 3D nano-structures. In order to develop IBL further, highly charged ion (HCI) beams have been applied to IBL method in our research group. Considering a high reactivity of HCI beams in an irradiated material, it is expected that HCI beams enhance a productivity of damage in irradiated materials compared with singly charged ion beams. This effect will be observed as a change in etching speed of IBL process. In the present study, the HCI effect on IBL was investigated by irradiating Ar9+and Ar1+with the fluence of 6.3 × 1012to 4.7 × 1014ptcl./cm2, which is lower than that in our previous study (6.3 × 1014to 3.1 × 1015ptcl./cm2). The Ar9+and Ar1+ion beams with E = 90 keV, which were prepared by an irradiation facility of HCI beams at Kochi University of Technology, were irradiated onto spin-on-glass (SOG) through a stencil mask. In order to investigate an etching process by using BHF solution, the fabrication depth of SOG surface was measured as a function of an etching time. The depth measurements show that an irradiation of HCI beams enhances an etching speed and the fabrication depth. For example, the fabrication depth with Ar9+beams, which is at least 100 nm deeper than that with Ar1+beams, was achieved. The present result shows a priority of HCI beams to fabricate deeper 3D-structures and gives information required to optimize the fabrication process with keeping a good precision. ? 2007 Elsevier B.V. All rights reserved.