Study on Mechanism of Micro-machining using Friction Force Microscope

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In order to control the process of the nanometer-scale machining precisely, it is necessary to understand the mechanism of nanometer-scale removing process. In this point of view, a unique nano-machining and measurement system, which utilizes the mechanisms of FFM, has been newly developed for the purpose of observation on nano-machining in the scale from 1 to 100 nm. The system has both a original micro-cantilever for machining and an ordinary micro-cantilever for AEM measurement, and it also has a device which can exchange two cantilevers alternatively. To evaluate the performance of the system, a single crystal silicon was machined and scratched by a simple diamond grain which was fixed on the end of the cantilever. Then, the system could make 2 mu m x 2 mu m square holes of 70 nm in maximum depth. Moreover it also could make scratches obviously and measure the lateral reaction force at a time. Those results proved the system effective in nano-machining experiments. The shape of the traces machined by different cantilevers vary obviously because of the geometrical irregularity of the tip. And, even in case of machined by same cantilever, the traces also vary little by little as repeat machining because of the wear of the cutting edge. The depth of the trace machined by the area-scanning is about 10 times as large as the line-scanning. To explain the reason, a machining model was proposed, in which machining and removing efficiency is raised up by the feed of the scanning line. The lateral machining force changed by the type of scanning, and the shape of the cutting chips, which were observed by SEM, also vary by the feed condition. These results could prove the proposed model.