Nanoscale 3D Printing

Micro- and nanofabrication, as used for integrated circuit manufacturing, consists predominantly of a large number of repetitive 2D processing steps. Modern etching technologies have enabled what essentially are 2.5D structures, but large-area free-form 3D patterning at the nanoscale has been out of reach. This paradigm is now increasingly being challenged by advances in 3D printing technology, with two-photon polymerization (2PP) quickly becoming the new standard for micro- and nanofabrication. As opposed to stereolithography, where a UV laser scans the surface of a photosensitive material to produce a 2D pattern of polymerized material, 2PP polymerizes a material along the trace of the laser focus moving through a resin, thus enabling fabrication of fully 3D patterns. This difference in pattern generation is achieved by initiation of 2PP within the small volume of the material via precise focusing of NIR femtosecond laser pulses. As such, 2PP achieves higher resolution then stereolithography and is not limited to the traditional layer-by-layer approach. In 2019, the University of Canterbury Nanofabrication Laboratory, housed in the Electrical and Computer Engineering Department, installed a commercial 2PP system in form of a Nanoscribe Photonic Professional GT2 (PPGT2). In this seminar, we will discuss the physics behind 2PP, introduce the PPGT2 system and operation, and showcase a selection of application examples [1,2], both in form of general micro- and nano structures, as well as diffractive optical elements.