Mechanism of mechanical nanolithography using self-excitation microcantilever

Use of the microcantilever in an atomic force microscope (AFM) that has been enhanced with a diamond abrasive grain has emerged as a powerful nanolithography technique. Vibration-assisted mechanical nanolithography, particularly when using self-excited oscillations generated by the microcantilever, enhances machining efficiency, and the machining depth can be controlled conveniently by manipulating the microcantilever’s steady-state amplitude. In this research, the formation mechanism of the machined grooves is investigated. Two machining modes are proposed: one involves the impacts of the diamond abrasive grain equipped on the microcantilever’s tip when used as the formation tool, while the other relies on pressing and rubbing of the diamond abrasive grain. Furthermore, effective control of the machining depth in both machining modes via amplitude manipulation is proposed theoretically. Mechanical nanolithography experiments are performed using a redesigned microcantilever, and the machining mode is determined by observing the new machining tool’s vibration profile during the machining process. As a result, under reduced pressing loads, grooves are formed by the tool’s impacts, whereas when the pressing load exceeds a threshold, the sample surface is pressed and rubbed by the diamond abrasive grain. Furthermore, the effectiveness of machining depth control through amplitude manipulation is demonstrated experimentally.