AFM-BASED NANOMACHINING FOR NANO-FABRICATION PRCESSES: MD SIMULATION AND AFM EXPERIMENTAL VERIFICATION
R Promyoo and H El-Mounayri and A Martini, PROCEEDINGS OF THE ASME INTERNATIONAL MANUFACTURING SCIENCE AND ENGINEERING CONFERENCE 2010, VOL 2, 405-414 (2011).
Recent developments in science and engineering have advanced the fabrication techniques for micro/nanodevices. Among them, the atomic force microscope (AFM) has already been used for nanomachining and nanofabrication such as nanolithography, nanowriting and nanopattcrning. This paper describes the development and validation of computational models for AFM-based nanomachining (nanoindentation and nanoscratching). The Molecular Dynamics (MD) technique is used to model and simulate mechanical indentation and scratching at the nanoscale for the case of gold. The simulation allows for the prediction of indentation forces and the friction force at the interface between all indenter and a substrate. The effect of scratching speeds on indentation force and friction coefficient is investigated. The material deformation and indentation geometry are extracted based on the final locations of the atoms, which have been displaced by the rigid tool. In addition to the modeling, an AFM was used to conduct actual indentation at the nanoscale, and provide measurements to which the MD simulation predictions call be compared. The AFM provides resolution on the nanometer (lateral) and angstrom (vertical) scales. A three-sided pyramid indenter (with a radius of curvature similar to 25 nm) is raster scanned on top of the surface and in contact with it. It can be observed from the MD simulation results that the indentation force increases as the depth of indentation increases, but decreases as the scratching speed increases. Moreover, the friction coefficient is found to be independent of scratching speed.
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