High-Fidelity 3D-Nanoprinting via Focused Electron Beams: Growth Fundamentals

Abstract

While 3D-printing is currently experiencing significant growth and having a significant impact on science and technology, the expansion into the nanoworld is still a highly challenging task. Among the increasing number of approaches, focused electron-beam-induced deposition (FEBID) was recently demonstrated to be a viable candidate toward a generic direct-write fabrication technology with spatial nanometer accuracy for complex shaped 3D-nanoarchitectures. In this comprehensive study, we explore the parameter space for 3D-FEBID and investigate the implications of individual and interdependent parameters on freestanding nanosegments, which act as a fundamental building block for complex 3D-structures. In particular, the study provides new basic insights such as precursor transport limitations and angle dependent growth rates, both essential for high-fidelity fabrication. Complemented by practical aspects, we provide both basic insights in 3D-growth dynamics and technical guidance for specific process adaption to enable predictable and reliable direct-write synthesis of freestanding 3D-nanoarchitectures.

Tunable 3D Nanoresonators for Gas‐Sensing Applications

“…Next, quasi‐1D Pt–C nanopillars were grown via FEBID in spot mode in the center of (P) (see orange arrow in (a) and side view scheme in (b)) with target heights of (5 ± 0.1) µm (derived from growth rate studies) using primary electron energies of 5, 10, 20, and 30 keV. In all cases, the lowest possible beam currents of 5, 7.5, 13, and 21, respectively, were used to establish best working regime conditions . In a second experimental series, we fixed the primary electron energy at 30 keV and varied the beam current from 21, 44, and 150 pA to study the implications of a changing working regime on the Young's modulus.…”

Mechanical Properties of 3D Nanostructures Obtained by Focused Electron/Ion Beam-Induced Deposition: A Review

“…Please note that the aforementioned considerations apply for vertical pillars. When fabricating more complex 3D architectures with overhanging features [65,[73][74][75], localized beam heating has been identified as the main effect concerning the fabrication precision, as recently revealed by Fowlkes et al [76,77], which also has implications on the chemical state of the matrix and by that on the mechanical properties. However, as heating depends on the design and the feature diameters, one would prefer to have no temperature differences during growth in order to spatially maintain the mechanical properties.…”

“…In contrast, MLR conditions provide more particles than molecules, where the former can lead to additional processes such as matrix modifications, although feature sizes are basically larger [10,79,80]. The exception for the latter are taller, freestanding 3D objects, where strongly tilted elements can reveal widths down to the sub-20-nm regime [73,74]. The underlying processes of such situations are related to the convolution of the relative angle between the growing element and the incoming electron beam, the applied primary energies, and the shift to gas flux adsorption-dominated replenishment, leading to varying cross-sectional profiles [65].…”

“…Typically, FEBID and FIBID do not naturally result in flat top pillars, as seen in Figure 13c. The deposition parameters would need to be very carefully tuned [73,101]. However, if thick pillars can be grown large enough, then cutting away the round top by Ga-FIB is an option as far as no changes in the pillar material are induced.…”

3D Nano-Probes for Thermal Microscopy

“…With the recent introduction of controlled 3D nano-printing via focused electron beam induced deposition (FEBID) [1,2,3], entirely new ranges of applications such as nano-optics [4], -sensors [5],magnetics [6] or -mechanics comes within reach whose fabrication is extremely challenging or even impossible with alternative techniques. In this study, we use 3D FEBID for the direct-write fabrication of thermal 3D nano-probes for further application in Scanning Thermal Microscopy (SThM).…”