As the size of electronic and mechanical devices shrinks to the nanometre regime, performance begins to be dominated by surface forces. For example, friction, wear and adhesion are known to be central challenges in the design of reliable micro- and nano-electromechanical systems (MEMS/NEMS). Because of the complexity of the physical and chemical mechanisms underlying atomic-level tribology, it is still not possible to accurately and reliably predict the response when two surfaces come into contact at the nanoscale. Fundamental scientific studies are the means by which these insights may be gained. We review recent advances in the experimental, theoretical and computational studies of nanotribology. In particular, we focus on the latest developments in atomic force microscopy and molecular dynamics simulations and their application to the study of single-asperity contact.

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Recent advances in single-asperity nanotribology

Ultra-precision grinding is primarily used to generate high quality and functional parts usually made from hard and difficult to machine materials. The objective of ultra-precision grinding is to generate parts with high surface finish, high form accuracy and surface integrity for the electronic and optical industries as well as for astronomical applications. This keynote paper introduces general aspects of ultra-precision grinding techniques and point out the essential features of ultra-precision grinding. In particular, the keynote paper reviews the state-of-the-art regarding applied grinding tools, ultra-precision machine tools and grinding processes. Finally, selected examples of advanced ultra-precision grinding processes are presented.

Ultra-precision grinding

This paper provides a comprehensive review of the literature, mostly of the last 10-15 years, that is enhancing our understanding of the mechanics of the rapidly growing field of micromachining. The paper focuses on the mechanics of the process, discussing both experimental and modeling studies, and includes some work that, while not directly focused on micromachining, provides important insights to the field. Experimental work includes the size effect and minimum chip thickness effect, elastic-plastic deformation, and microstructure effects in micromachining. Modeling studies include molecular dynamics methods, finite element methods, mechanistic modeling work, and the emerging field of multiscale modeling. Some comments on future needs and directions are also offered.

/pdf/the-mechanics-of-machining-at-the-microscale-assessment-of-9kfioocc84.pdf

The Mechanics of Machining at the Microscale: Assessment of the Current State of the Science

https://escholarship.org/content/qt6226v74d/qt6226v74d.pdf?t=qki0rx

Synergetic effects of surface texturing and solid lubricants to tailor friction and wear – A review

Besides continuing effort in developing MEMS-based manufacturing techniques, latest effort in micro-manufacturing is also in non-MEMS-based manufacturing. Research and technological development in this field is encouraged by the increased demand on micro-components as well as promised development in the scaling down of the traditional macro-manufacturing processes for micro-length-scale manufacturing. This paper highlights some EU funded research activities in micro/nano-manufacturing, and gives examples of the latest development in micro-manufacturing methods/techniques, process chains, hybrid processes, manufacturing equipment and supporting technologies/device, etc., which is followed by a summary of the achievements of the EU MASMICRO project. Finally, concluding remarks are given, which raise several issues concerning further development in micro-manufacturing.

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Micro-manufacturing: research, technology outcomes and development issues

Defect-free fabrication for single crystal silicon substrate by chemo-mechanical grinding

Several molecular dynamics simulations are performed, in order to clarify the atomic-scale stick-slip phenomenon which is commonly observed in the surface measurement using an atomic fine microscope (AFM). In the molecular dynamics simulations, a specimen and a slider are assumed to consist of monocrystalline copper and rigid diamond, respectively, and a Morse potential is postulated between a pair of atoms. Atomic behavior in a plane corresponding to the (111) crystal plane is simulated, dealing with a planar strain problem where the effect of the three-dimensional interatomic force and the spring constant of the AFM cantilever are also taken into consideration. Influence of the cantilever stiffness and dynamics of the specimen surface atoms on the atomic-scale stick-slip phenomenon are investigated. The simulation confirms that the atomic-scale stick-slip phenomenon can be expressed by a molecular dynamics simulation and that the stick-slip phenomenon of the surface atoms of the specimen affects the stick-slip phenomenon of the spring force. These results indicate that molecular dynamics simulation has an advantage in deciding the spring constant of cantilevers.

https://iopscience.iop.org/article/10.1088/0957-4484/9/2/014/pdf

Molecular dynamics simulation of friction on the atomic scale

Finishing process of quartz glass substrate is meeting great challenges to fulfill the requirements of photomask for photolithography applications. For the final finishing of the substrate surface, chemical mechanical polishing (CMP) is often utilized. Those free abrasive processes are able to offer a great surface roughness, but sacrifice profile accuracy. On the other hand, the fixed abrasive process or grinding is known as a promising solution to improve accuracy of profile geometry, but always introduces damaged layer. Chemo-mechanical grinding (CMG) is potentially emerging defect-free machining process which combines the advantages of fixed abrasive machining and CMP. In order to simultaneously achieve high surface quality and high profile accuracy, CMG process has been applied into machining of large size quartz glass substrates for photomask use. Reported in this paper are CMG performances in finishing of quartz glass substrates including material removal rate (MRR), surface roughness, flatness and optical characteristics.

Research on chemo-mechanical grinding of large size quartz glass substrate

Simulation and experimental analysis of super high-speed grinding of ductile material

The demand for ultra-thin silicon wafers has escalated in recent years with the rapid development of miniaturized electronic devices. In this work, diamond grinding for thinning silicon wafers was carried out on an ultra-precision grinding machine. The thinning performance and the minimum wafer thickness were investigated under different grinding conditions. It was found that the grain depth of cut that was used to characterize the overall grinding conditions played an important role in the determination of the final grinding performance. The relationship between the subsurface damage of the ground wafer and the minimum wafer thickness achieved was also revealed.

Jun Shimizu

Papers

Defect-free fabrication for single crystal silicon substrate by chemo-mechanical grinding

Molecular dynamics simulation of friction on the atomic scale

Research on chemo-mechanical grinding of large size quartz glass substrate

Simulation and experimental analysis of super high-speed grinding of ductile material

A study on the diamond grinding of ultra-thin silicon wafers