森田 昇

In order to improve the laser micro-machinability of borosilicate glass, the glass surface was doped with metal (silver or copper) ions by an electric field-assisted ion-exchange method. Doped ions drifted and diffused into the glass substrate under a DC electric field. The concentration of metal ions within the doped area was approximately constant because the ion penetration was caused by substitution between dopant metal and inherent sodium ions. Nanosecond ultraviolet laser irradiation of metal-containing regions produced flat, smooth and defect-free holes. However, the shapes of holes were degraded when the processed hole bottoms reached ion penetration depths. A numerical analysis of ionic drift-diffusion behaviour in glass material under an electric field was also carried out. The calculated results for penetration depth and ionic flux showed good agreement with the measured values.

Micro-grooves fabrication is increasing due to its importance in different technology fields, as they are required for higher functional applications such as the development of optical lens or micro channels for heat exchangers. A novel method based on the technology developed for Atomic Force Microscopes (AFM) nano-cutting is proposed, where nano-scratches are made using a micro-cantilever with a sharp tip where a normal load sufficient to remove material is applied. Instead of a rigid system to control the relative position between the tool and the workpiece, AFM nano-cutting uses a force feedback control (FBC) of the normal load on the tool edge in order to maintain a constant cutting depth during the manufacture. Due to the limited scale range of AFM machining, a larger mechanism was developed and consists on a XYZ-stage system where an elastic leaf spring type tool holder is mounted with a diamond tool chip. FBC is not yet implemented on this system; however, basic experiments (micro-grooves cutting) were performed on different materials to verify the feasibility of this setup. With these results, it is possible to analyze the relationship between static indentation tests and the normal load required during the micro-grooves fabrication.

The measurement of cutting force is important to monitor the status of the process during micro drilling. It is used the cutting dynamometer, the shape of the workpiece is restricted and must be set to the center. These problems can be resolved by adoption of the spindle with built-in sensor. The purpose of this study is the development of the sensor built-in spindle for micro drilling that the thrust and the torque can be measured simultaneously. The structure of the spindle uses a static pressure bearing and a capacitance sensor to realize high accuracy measurement. As a result of study, this spindle was able to measure very weak thrust and torque to occur by micro drilling of 0.05mm in diameter. These results of research can be constructed the advanced processing system which prevents the breakage of the drill by monitoring the cutting force.

Cutting and friction experiments were conducted in various atmospheres to investigate the chemical effect on textured cutting tools. The cutting experiments indicated that the atmosphere affected the machinability of the textured tools; a larger effect was observed in the presence of gas such as oxygen. A ball-on-disk friction apparatus was developed and used for the friction experiments. Smaller friction coefficients were observed in the presence of oxygen, a trend similar to that observed during the cutting experiments. These results indicate that oxidation is an important factor in determining the texture effect for machining aluminum alloy.

In this study, brittle materials were mechanically modified under precise normal force control at the mN similar to mu N level using POD tools as a nano tool. The lab-made POD attached micro cantilevers were customized for tribo nanolithography. The machined patterns were measured under an atomic force microscope (AFM) to obtain the machining characteristics of the samples for each set of conditions. Then the samples were etched using aqueous solution to verify the etch characteristics of the machined surface. Our results showed that either protruding or depressed patterns could be generated on the scratched surface by controlling normal load, scan pitch, and etching condition. The unique mask effect of brittle material after mechanical scratching under POD tool can be controlled by the conventional mechanical machining conditions such as chip formation, plastic flow, and material removal. We used SEM, TEM, SIMS, and AFM to investigate the etch characteristics and structural change of brittle material under nano scale mechanical machining conditions.

This study investigated methods of fabricating high-aspect-ratio structures on a silicon surface using a combination of tribo-nanolithography and wet chemical etching. Tribo-nanolithography forms an amorphous phase on a single-crystal silicon surface that has an etch resistance against potassium hydroxide so that a protruding structure can be fabricated by wet chemical etching. To fabricate high-aspect-ratio structures, (110)-oriented silicon was used, and the effect of machining parameters on the structure shape was investigated. The results showed that a structure with vertical side walls could be fabricated by machining along the < 112 > direction. The etch resistance against potassium hydroxide depended on the normal load and number of repetitions, and the width and the maximum height were functions of these conditions. The aspect ratio of the structure increased with the etch time as long as the amorphous phase was maintained. A sub-micrometer-scale high-aspect-ratio structure was fabricated based on these results, demonstrating the possibility of using this simple and effective method.

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.

We developed novel cutting tools that had either microscale or nanoscale textures on their surfaces. Texturing microscale or nanoscale features on a solid surface allowed us to control the tribological characteristics of the tool. The textures, which had pitches and depths ranging from several hundreds of nanometers to several tens of micrometers, were fabricated utilizing the ablation and interference phenomena of a femtosecond laser. The effect of the texture shape on the machinability of an aluminum alloy was investigated with a turning experiment applying the minimum quantity lubrication method. The texture decreased the cutting force due to the corresponding reduction in the friction on the rake face. This effect strongly depended on the direction of the texture; lower cutting forces were achieved when the texture was perpendicular to the chip flow direction rather than parallel. This effect was only observed at high cutting speeds over 420 m/min. These results indicate that the developed tools effectively improved the machinability of the alloy. (C) 2008 Elsevier Inc. All rights reserved.

本研究は，GaAs半導体の研削加工におけるクラック発生機構を明らかにすることを目的としている．前報では，傾斜ステージを持ったスクラッチ加工機を試作し，これを用いたGaAsの加工実験を行った．これより，GaAsにおけるクラックの発生は結晶方位に強く依存し，その傾向はSiのそれとは大きく異なることがわかった．本報ではこの現象を静的に観察するため，ビッカース圧子による押込み加工を行った．その結果，クラックの発生は結晶方位によって大きく変化し，<100>方向で最もメジアンクラックが生じやすいことがわかった．一方，[011]，[0-1-1]方向では[0-11]，[01-1]方向と比較してラテラルクラックやメジアンクラックが生じやすい．また，加工痕を隣接させて加工すると，応力場の干渉によって脆性破壊が生じやすい．このため脆性破壊を生じないためには，切込み量や加工痕間の距離が極めて重要な因子となることがわかった．

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 frictional 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.

We propose a method for fabricating three-dimensional structures on GaAs surfaces using electron beam (EB) irradiation followed by wet chemical etching. An etch-resistant hydrocarbon layer forms on the GaAs surface with the EB irradiation. Structures can be fabricated after etching using the hydrocarbon layer to block the etching. The height dependence on the irradiation and etching conditions was investigated as a means of controlling the height of the structures. A higher structure was fabricated at higher doses. The etching selectivity changed with the concentration of the etchant. A three-dimensional structure was fabricated based on these results, demonstrating the possible use of this method as a novel three-dimensional fabrication method for GaAs surfaces.

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 Ar(9+) and Ar(1+) with the fluence of 6.3 x 10(12) to 4.7 x 10(14) ptcl./cm(2), which is lower than that in our previous study (6.3 x 10(14) to 3.1 x 10(15) ptcl./cm(2)). The Ar(9+) and Ar(1+) 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 Ar(9+) beams, which is at least 100 urn deeper than that with Ar(1+) 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. (C) 2007 Elsevier B.V. All rights reserved.

In various fields of nanotechnology, the importance of nanoscale three-dimensional (31)) 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 At ions. These results show the possibilities of the IBL technique with HCI beams in the field of nanoscale 3D fabrication. (C) 2008 American Institute of Physics.

This report describes a method of sub-micrometer-scale rapid patterning on a Zr-based metallic glass surface using a combination of focused ion beam irradiation and wet chemical etching. We found that a Zr- based metallic glass surface irradiated with Ga+ ions could be selectively etched; a concave structure with a width and depth of several tens to hundreds of nanometers rapidly formed in the irradiated area. Moreover, we determined that the etching was enhanced by the presence of Ga+ ions rather than a change in the crystal structure, and the structure could be fabricated while the substrate remained amorphous. The shape of the structure was principally a function of the dose and the etch time.

Nanoscale fabrication of silicon substrate based on the use of atomic force microscopy (AFM) followed by chemical etching was demonstrated. A specially designed cantilever with a diamond tip, allowing the formation of damaged layer on silicon substrate by a simple scratching process, has been applied instead of conventional silicon cantilever for scanning. A thin damaged layer forms in the substrate at the diamond tip-sample junction along scanning path of the tip, which was found to be a low crystallized amorphous silicon layer. Hence, these sequential processes, called tribo-nanolithography, TNL, can fabricate 2D or 3D microstructures in nanometer range. Diamond tip fabrication processes for TNL follow the micro-patterning, wet chemical etching and CVD based on MEMS processes. The developed TNL tools show outstanding machinabiliity against single crystal silicon wafer. Hence, they are expected to have a possibility for industrial applications as a micro-to-nano-machining tool. In our previous work, is has been clearly known that the damaged layer withstands against aqueous potassium hydroxide solution, while it dissolves in diluted hydro fluoric solution. This study demonstrates the effect of various machining parameters on mask layer, followed by wet chemical etching in potassium hydroxide and hydro fluoric solution. (c) 2006 Elsevier B.V. All rights reserved.

This study investigated the nanomachining of metallic glass surfaces using an Atomic Force Microscope (AFM). To reveal the nanomachining characteristics of metallic glass, machining experiments were conducted under various machining parameters. The metallic glass was machined to fabricate an 8-nm-deep by 120-nm-wide groove pattern. It was found that metallic glass is a more challenging material to machine than single-crystal silicon. The tool life is significantly shorter, although it can be improved somewhat by machining in water. Observation of the machining residue revealed that continuous and shear cutting chips were generated that differed from those generated by machining amorphous silicon. © 2007 Inderscience Enterprises Ltd.

This study sought to fabricate a three-dimensional structure on a silicon surface using a combination of tribo-nanolithography (TNL) and wet chemical etching. TNL forms an amorphous phase on a single-crystal silicon surface that has an etch resistance against potassium hydroxide (KOH). A protruding structure can then fabricated with wet chemical etching. When the machined silicon is etched in hydrofluoric acid (HF), the amorphous silicon phase formed by the TNL is selectively etched whereas the non-machined silicon withstands the etching. The etch resistance of the TNL-induced amorphous phase can be controlled by the machining conditions, such as the normal load, overlap ratio, and number of times the area is machined. In this study, the resulting mechanism controlling the etch resistance was examined under different machining conditions. Changes in the etch resistance due to the normal load were caused by the thickness of the amorphous phase, while changes in the resistance due to the overlap ratio or number of times the area was machined were caused by the density of the amorphous phase.

Ion beam lithography of a silicon surface using an Ar ion beam with an ion energy in the order of hundreds of keV is demonstrated in this study. A specially designed ion irradiation facility was employed that enabled generation and irradiation with a highly accelerated and highly charged At ion beam. An ion-beam-induced amorphous layer on a silicon substrate can be selectively etched in hydrofluoric acid, whereas, a non-irradiated area is scarcely etched and, consequently, a concave structure can be fabricated on the irradiated area. To control the depth of the structure, parameters for dependence of the depth on ion irradiation were investigated. As a result, the depth of irradiated area can be controlled by the ion energy that is adjusted by the acceleration voltage and the ion charge. In addition, the etch resistance of the irradiated area increases with an increase in ion energy due to the crystalline layer formed on the surface. Simulation results reveal that the depth is strongly related to the defect distribution induced by ion irradiation. These results indicate the potential use of this method for novel three-dimensional lithography. (c) 2006 Elsevier B.V. All rights reserved.

A simple and rapid method is proposed for nanoscale patterning on a metallic glass surface using focused ion beam irradiation followed by wet etching. It was found that the etch rate of a metallic glass surface irradiated with Ga+ ions could be drastically changed, and rapid patterning was possible with this method. Cross-sectional transmission electron microscopy observation reveals that the metallic glass substrate maintains an amorphous phase following irradiation. Etching enhancement was not observed for irradiation with Ar+ ions. The results indicate that enhancement of etching results from the presence of implanted Ga+ ions rather than a change in crystallography. (c) 2006 American Institute of Physics.

This study is intended to develop a machining cantilever for use of nanofabrication method called tribo-nanolithography (TNL). In the TNL method, diamond tip with an arbitrary tip radius is necessary to fabricate precise nanostructure. To control the shape of cutting edge, anisotropic and subsequent isotropic wet etching method is applied in a fabrication process of silicon mold. The tip radius increases with an increase in time of isotropic wet etching, and diamond tip with arbitrary tip radius can be fabricated. Nanomachining experiment using friction force microscopy (FFM) is conducted to evaluate developed cantilever as a nanomachining tool for the TNL. As a consequence, silicon surface can be machined without removal, and this indicates possible use for the TNL. SEM observation reveals that there are a number of particles on the cutting edge that lead a negative influence on the machined area, and they could be improved by increasing machining distance, owing to the wear and/or drop of the particles. Finally, nanostructure with a line width of 120nm could be fabricated by the TNL using developed cantilever, and this indicates that the developed cantilever is effective nanomachining tool for the TNL.

This paper investigates nanomachining of single-crystal silicon using an atomic force microscope with a diamond-tip cantilever To enable nanomachining of silicon, a nanomachining cantilever with a pyramidal diamond tip was developed using a combination of photolithography and hot-filament chemical vapor deposition. Nanomachining experiments on silicon using the cantilever are demonstrated under various machining parameters. The silicon surface can be removed with a rate of several tens to hundreds of nanometers in ductile mode, and the cantilever shows superior wear resistance. The experiments demonstrate successful nanomachining of single-crystal silicon.

A simple process of fabricating a three-dimensional nanostructure on a silicon surface was investigated in this study. The silicon surface area irradiated by focused ion beam (FIB) was selectively etched in HF, whereas the non-irradiated area was scarcely etched, and consequently, a concave nanostructure was fabricated on the irradiated area. To control the depth of the nanostructure, the depth dependence on ion irradiation parameters was investigated. As a result, it was found that the depth of the irradiated area can be controlled by changing ion irradiation parameters, such as dose and ion energy. Under a. low-dose condition, the irradiated area was scarcely etched, due to the formation of an amorphous layer on the interior of silicon. Subsequently, it was etched in KOH to evaluate the mechanism of this phenomenon. In addition, the surface roughness dependence on ion irradiation parameters was investigated. Finally, three-dimensional nanostructures were fabricated on the basis of these results, suggesting that this method is a novel three-dimensional nanofabrication method.

In order to fabricate a nanoscale three-dimensional (3D) structure by using the ion-beam lithography (IBL), we tried to control the etching rate and the etching depth by means of the charge state, the beam energy, and the fluence of the ion beam. Ar-ion beams with E=90 keV and 80-400 keV were irradiated onto spin on glass (SOG) and Si, respectively. The Ar ions were prepared by a facility built at the Kochi University of Technology, which included an electron cyclotron resonance ion source (NANOGAN, 10 GHz). It was found that the irradiation of highly charged ions (HCIs) enhanced the etching rate of SOG. The etching rate and etching depth of Si were controlled by the beam energy and the fluence of Ar4+ ions. The present results show the effectiveness of IBL with HCIs to fabricate a nanoscale 3D structure. (c) 2006 American Institute of Physics.

Nano-scale fabrication of silicon substrate based on the use of atomic force microscopy (AFM) was demonstrated. A specially designed cantilever with diamond tip allows the formation of damaged layer on silicon substrate by a simple scratching process. A thin damaged layer forms in the substrate along scanning path of the tip. The damaged layer withstands against wet chemical etching in aqueous KOH solution. Diamond tip acts as a patterning tool like mask film for lithography process. Hence these sequential processes, called tribo-nanolithography, TNL, can fabricate 2D or 3D micro structures in nanometer range. This study demonstrates the fabrication processes of the micro cantilever and diamond tip as a tool for TNL. The developed TNL tools show outstanding machinability against single crystal silicon wafer. Hence, they are expected to have a possibility for industrial applications as a micro-to-nano machining tool.

The etching resistance characteristics of a Focused Ion Beam (FIB) irradiated silicon surface against KOH are investigated in this study. An FIB irradiated silicon surface can withstand etching in KOH solution, whereas the non-irradiated area is etched and consequently, a protruding nanostructure can be fabricated on the irradiated area. Height dependence of the nanostructure on the FIB irradiating conditions is investigated in order to control the shape of the nanostructure for application to three-dimensional nanofabrication. As a consequence, it was found that the height of the nanostructure can be controlled by FIB irradiating conditions such as dose and acceleration voltage. The mechanism is investigated by a selective etching method using HF solution. The results of a simulation indicate that the amorphous layer induced by ion irradiation is strongly related to this phenomenon. In addition, surface roughness and line width dependence was investigated, and these results indicate the potential use of this method as a novel three-dimensional nanofabrication process. Copyright © 2006 Inderscience Enterprises Ltd.

A simple process to fabricate a three-dimensional structure on silicon surface was developed by using tribo-nanolithography (TNL) in an aqueous KOH solution. An inclined rectangular structure can be fabricated by a process where a thin amorphous layer, having corrosion resistance against KOH, rapidly forms on the substrate at the diamond tip sample junction along the scanning pass of the tip, while simultaneously, the area not covered with the amorphous layer is being etched in KOH. An inclination of structure can be controlled by the scanning velocity. The scanning pitch is related to the corrosion resistance of the amorphous layer, rather than the change of inclination. We fabricated a structure having multiple inclinations based on these results, which indicates the possibility of using the TNL for three-dimensional nanofabrication. (c) 2005 American Vacuum Society.

Tribo-nanolithography (TNL) can form an affected layer on a silicon surface that is resistant to corrosion by KOH, and a nanostructure can be fabricated by combination with wet chemical etching. Transmission electron microscope (TEM), Auger electron spectroscopy (AES) and secondary ion mass spectrometry (SIMS) analyses were utilized to investigate the mechanism of the etch stop effect on the machined area. TEM observation revealed that the silicon crystal structure was converted to an amorphous structure measuring approximately 15-20 nm. AES and SIMS analyses indicated that the amorphous layer consisted entirely of silicon. Thus, the mechanism of the etch stop effect on the machined area was determined to result from the formation of an amorphous silicon structure.

近年, 工具の性能向上にともない, 加工の高速化, 高性能化への要求はますます高くなっている. 本研究では, 高速切削における工具材種の影響について明らかにすることを目的とし, 超硬, PCD, DLCの各種工具を用いて, アルミニウム合金に対し正面切削を行った. そのときの, 切削抵抗, 仕上げ面あらさ, 工具摩耗を測定した. その結果, PCD工具を用いた場合, 他の工具を用いたときよりも切削抵抗を減少でき, 良好な仕上げ面を得られることが明らかとなった. また, 工具摩耗も抑制できることが明らかとなった.

プレス成型法では, 一般的に切れ味のよい砥石を安価に製作することができる. しかし, カレンダーロール法に比べ曲げ強度や回転破壊強度が小さく, 砥石寿命も短いという問題点があった. この課題を達成するため, 本研究では乳鉢低速撹拌機を用いた砥粒・充填剤・結合剤の均一撹拌方法の確立, 砥石性能に及ぼす充填剤と結合剤の添加率の影響及びその適正条件について検討を行い, 切れ味と強度を兼ね備えた安価な切断砥石を開発した. 切断加工には一般に加工油剤が用いられているが, 近年, 環境負荷の観点からその使用を減少させる傾向にある. そこで, 粉末寒天を配合した切断砥石にポリエチレングリコールを含浸させることで, 砥石自身に潤滑機能と冷却機能を持たせた環境に優しい乾式切断砥石を提案し, プレス成型法で開発することに成功した.

To achieve rapid patterning of quartz surface, ion beam irradiation using focused ion beam (FIB) and succeeding buffered hydrofluoric acid wet etching of quartz was examined. The etched depths of quartz saturated with increasing of ion dose and the optimum wet etching time was 60 s. This process improved surface roughness and fabricated a 34 nm depth and 487 nm width line pattern using 330 nm diameter FIB irradiation.

In this study, we proposed a fabrication process of diamond array tool for micro-to-nano machining. The diamond array tools are fabricated by depositing polycrystalline diamond using CVD on silicon molds which are made by anisotropic wet etching of the single crystal silicon. It has a characteristic which can control a tip shape of cutting edge with different silicon planes. Moreover, the sizes and the arrangements of cutting edge are decided minutely by changing mask pattern on silicon substrate. The diamond array tools are expected to have a possibility of industrial applications as a micro-to-nano machining tool.

The tribonanolithography (TNL) of silicon substrate in aqueous solution based on the use of atomic force microscopy is demonstrated. A specially designed cantilever with a diamond tip, which allows the formation of a protruding oxide layer several nanometers high using a simple machining process with a given pitch, was applied to the TNL process in KOH solution instead of a conventional silicon cantilever. The anisotropic wet etching stopped in the modified area because silicon oxide was resistant to corrosion by KOH. The fabrication of a three-dimensional slant nanostructure is possible by taking advantage of the time lag of oxide formation during etching in KOH solution. (C) 2004 American Institute of Physics.