Nanoscale 3D printing process using nano particle deposition system and focused ion beam

Abstract

A novel nanoscale 3D printing process was developed with the main stream of down-scaling of structures and systems. In order to find out the way of building 3D micro- and nanostructures with multimaterials, two technological paradigms of 3D printing and hybrid were combined to get the high impact of synergy by integrating nano particle deposition system (NPDS) and focused ion beam (FIB). The NPDS which sprays micro- and nano-sized particle at supersonic speed was utilized to layer-up thin films with multimaterials (ceramics and metals). FIB was adopted as a profiling nanostructures to the single and multilayer of thin films, i.e., profile cutting. In order to show the feasibility of multimaterial processing through NPDS, various kinds of materials of metal and ceramic were deposited on various substrate such as metal, ceramic and polymers. Among those film materials, Sn, TiO2 and Al2O3 were investigated deeply as an engineering film. The deposition characteristics were studied by controlling the feed rate and stand-off distance. Each films physical properties were investigated for the verification as engineering films. The hardness, the elastic Modulus, bonding strength (peel-put test and work of adhesion) and microstructural changes were investigated. Furthermore, the bonding mechanism of metal and ceramic by NPDS was thoroughly investigated through the transmission electron microscope (TEM) by observing the interfaces of the particle-to-particle and particle-to-substrate. Especially in metal particle of Sn, the evolution mechanism, related to the bonding mechanism, from particle to film was proved with the experimental model. In order for the FIB to fabricate the target preciously, the advanced scan method, which adopted the dot-to-dot scan, was compared to the conventional scan method. In order to understand and avoid the defective structure from conventional scan method, the dwell time and the beam overlap were taken into consideration, and their effects were investigated. On the basis of these two parameters, several ion beam paths adaptive for 2D/3D target shapes were generated, and it improved the precision and the yield in FIB fabrication. In order to apply for 3D micro- and nanostructures with multimaterials, the combination and repetition of NPDS and FIB were performed by resulting in the feasibility of nanoscale 3D printing process. With a series of experiments the new process showed the multilayered structure with multimaterial deposition, the profiling of multilayered nanostructure by FIB, the selective profiling of nanostructure, and the repetition of both additive and subtractive processes as a printing process. Additionally, the NPDS showed not only its patterning resolution could be achieved below 50 nm but also it could build the high aspect ratio over 5 when it combined with FIB process. As an application, the smart material of shape memory alloy (NiTi) was utilized for the fabrication of functional nanostructure. The FIB showed that it can fabricate the nanostructure of NiTi with the 1st order bucking mode model, and the thermally-driven nanomanipulation of NiTi was performed via in situ TEM. The NPDS showed that it has the potential to deposit the metal material of Sn on NiTi with the good adhesion status.