Abstract
Focused electron beam induced deposition (FEBID) is a powerful technique for 3D-printing of complex nanodevices. However, for resolutions below 10 nm, it struggles to control size, morphology and composition of the structures, due to a lack of molecular-level understanding of the underlying irradiation-driven chemistry (IDC). Computational modeling is a tool to comprehend and further optimize FEBID-related technologies. Here we utilize a novel multiscale methodology which couples Monte Carlo simulations for radiation transport with irradiation-driven molecular dynamics for simulating IDC with atomistic resolution. Through an in depth analysis of hbox {W(CO)}_6 deposition on hbox {SiO}_2 and its subsequent irradiation with electrons, we provide a comprehensive description of the FEBID process and its intrinsic operation. Our analysis reveals that simulations deliver unprecedented results in modeling the FEBID process, demonstrating an excellent agreement with available experimental data of the simulated nanomaterial composition, microstructure and growth rate as a function of the primary beam parameters. The generality of the methodology provides a powerful tool to study versatile problems where IDC and multiscale phenomena play an essential role.
Highlights
MD26 have proved to be very useful in the atomistic-scale analysis of molecular fragmentation and chemical reactions up to nanoseconds and m icroseconds[26, 27]
This specific system is commonly used in focused electron beam induced deposition (FEBID) and has been extensively studied experimentally[12, 32, 38] and t heoretically[16, 24, 27]
In the present investigation we focus on better understanding the initial stages of the FEBID process, which can be currently monitored in experiments with electron m icroscopy[49]
Summary
MD26 have proved to be very useful in the atomistic-scale analysis of molecular fragmentation and chemical reactions up to nanoseconds and m icroseconds[26, 27]. In the present investigation we utilize a combination of the aforementioned MC and IDMD methodologies and perform the first inclusive simulation of radiation transport and effects in a complex system where all the FEBID-related processes (deposition, irradiation, replenishment) are accounted for. The dependence on the primary beam energy and current of the surface morphology, composition and growth rate of the created nanostructures was analyzed and was shown to be in an excellent agreement with results of available e xperiments[32]. This new methodology provides the necessary molecular-level insights into the key processes behind FEBID for its further development. The approach being general and readily applicable to any combination of radiation type and material, opens unprecedented possibilities in the simulation of many other problems where IDC and multiscale phenomena play an essential role, including a strochemistry[33, 34], nuclear and plasma p hysics15, radiotherapy[35, 36] or photoelectrochemistry[37]
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