AFM-based 3D Nanofabrication Using Ultrasonic Vibration Assisted Nanomachining

This paper explores AFM-based 3D nanomachining process assisted by ultrasonic vibration. 3D structures on polymethyl methacrylate (PMMA) substrates are fabricated by ultrasonic vibration-assisted nanomachining process. Two fabrication approaches for 3D structures are investigated in this study, which are layer-by-layer nanomachining and one pass nanomachining with the depth controlled by setpoint force. Critical parameters in the process are identified, including set-point force, overlap rate, amplitude of z vibration and machining speed. By regulating these parameters, stair-like 3D nanostructures are fabricated by multi-layer machining in Vector mode and Raster scan mode. Using different setpoint force for different feature depth, other nanostructures, such as convex and concave circles, are fabricated in Raster scan mode from grey-scale image. Under each mode, 3D nanostructure over microscale area can be fabricated in just a few minutes with the assistance of high frequency in-plane circular xy-vibration and ultrasonic tip-sample z-vibration.