Large-scale process optimization for focused ion beam 3-D nanofabrication

With the ever-decreasing size of manufactured objects, fabrication processes driven by charged particle beams, such as focused ion beam (FIB), become important for a wide spectrum of interdisciplinary applications. A designed three-dimensional (3-D) pattern to fabricate may contain millions of pixels, which will require solving an unprecedented large-scale problem for planning. This paper proposes a general framework of planning FIB milling for fabricating 3-D nanostructures, including model formulations to enable FIB for scalable and automated applications and a corresponding optimization model to support the process planning. The implementation of proposed work does not affect the fabrication quality and yet tremendously reduces the required computational time and data storage during planning. The proposed framework of process planning is further illustrated and verified by simulation and milling experiments of submicron features on Si and Si₃N₄. This research offers an accurate and economical solution to the realization from designs to actual micro/nanoscale models and builds a scientific foundation for immediate development of complex, yet more accurate and cost-effective, beam scanning techniques.