Study of tip wear for AFM-based vibration-assisted nanomachining process

Abstract

Nanofabrication technologies have many applications in science and engineering. Among different nanofabrication technologies, the tip-based vibration-assisted nanomachining using an Atomic Force Microscope (AFM) provides a low-cost, easy-to-setup approach for the production of nano-scale structures. As the resolution and quality of the machined features are greatly affected by the radius and sharpness of the tip, it is critical to investigate the behavior of tip wear during the nanomachining process and to estimate the tip life. In this work, the evolvement of the tip wear was characterized and modeled to predict tip wear and tip life for the nanomachining process. Besides the direct inspection of the tip radius using a Scanning Electron Microscope (SEM), the pull-off force between the AFM tip and the sample surface was found to correlate well with the tip radius, which enabled the measurement of tip wear directly without unloading the tip from the AFM. To study the tip wear at different conditions, the tip radius was measured from the pull-off force under a wide range of machining conditions. The change rates of the tip radius were significantly affected by the machining parameters, such as setpoint force and feed rate. Moreover, during the nanomachining process, three regions were identified for the tip wear evolvement as initial tip wear region, transition region, and tip failure region. Regression models were developed to describe the tip wear at different stages, and to estimate the tip life (i.e. when the tip needs to be changed), which provide usefully information for future process planning and process optimization.