3D Nanoprinting by Electron-Beam with an Ice Resist

Abstract

Following the general trend in the miniaturization of electronic devices, techniques that enable 3D printing at the nanometer scale are gaining momentum. As a widely used planar processing method, electron-beam lithography (EBL) can be employed to create 3D nanostructures in a layer-by-layer fashion. However, compared with other 3D printing techniques, EBL is limited by the stringent requirement of a range of fabrication equipment and complex fabrication processes. Here, we have demonstrated that EBL can be developed to a controllable 3D nanoprinting technology with the aid of ice resists. With carefully selected accelerating voltage, electron dose, and ice thickness, 3D objects can be efficiently printed in a single vacuum system through an iterative process of ice deposition and e-beam exposure. Mixed ice resists containing solid anisole and water are also introduced into the printing process, which offer a flexible control of the thickness of printed layers. Apart from carbonaceous objects obtained with our method, 3D printing of metals is also promising by employing organometallic compounds as ice resists. This study provides a fresh perspective in EBL-based nanofabrication and expands the spectrum of modern additive manufacturing.

Recording Messages on Nonplanar Objects by Cryogenic Electron‐Beam Writing

“…[ 13 ] Although the EDS measurement cannot provide the information of hydrogen, the change from a lower carbon content (before exposure) to a higher carbon content (after exposure) evidences the e‐beam induced radiolysis. [ 12 ] Moreover, we have found graphitic layers in the exposure product by using high‐resolution transmission electron microscopy (HRTEM), where the lattice fringes were clearly observed with the same interlayer spacing of ≈0.36 nm (Figure S3, Supporting Information). Lattice spacings and fast Fourier transform patterns (Figure S4, Supporting Information) show the presence of different planes of crystalline graphitic carbon, confirming the formation of graphitic structures in the product.…”

“…The composition of the exposed anisole has been recently investigated by Raman spectra and energy dispersive X‐ray spectroscopy (EDS). [ 12 ] The Raman spectrum (Figure S2, Supporting Information) shows that the exposed anisole should be a mixture of carbonaceous materials. Two relatively sharp peaks can be identified, referred to as G (1611 cm –1 ) and D+G (2961 cm –1 ) peaks.…”

Plasma-Assisted Microcontact Printing

“…From the printing mechanism as discussed earlier, the transport of FC materials is based on a thermal evaporation process and, thus, not strictly dependent upon direct contact between the stamp and the substrate, which distinguishes PA-μCP from most of the previous printing methods. A straightforward advantage of this patterning mechanism is that it allows for direct printing on structured surfaces, which is crucial for various multi-patterning techniques in semiconductor industries. , Figure a illustrates two multi-patterning process flows: litho–litho (LL) and litho–etch–litho (LEL). In a LL process, PA-μCP is first applied to create FC patterns on a clean Si substrate (here, line arrays are drawn for simplicity), then the same stamp is rotated by 90° manually, and PA-μCP is performed again with new coated FC.…”

“…A straightforward advantage of this patterning mechanism is that it allows for direct printing on structured surfaces, which is crucial for various multi-patterning techniques in semiconductor industries. 21,22 Figure 4a illustrates two multipatterning process flows: litho−litho (LL) and litho−etch− litho (LEL). In a LL process, PA-μCP is first applied to create FC patterns on a clean Si substrate (here, line arrays are drawn for simplicity), then the same stamp is rotated by 90°m anually, and PA-μCP is performed again with new coated FC.…”

Production and Patterning of Fluorescent Quantum Dots by Cryogenic Electron-Beam Writing

“…Anisole, a common solvent for poly­(methyl methacrylate) (PMMA) solution, gets solid and cross-linked after e-beam irradiation at cryogenic temperatures. Prior efforts have been aimed at its lithographic properties − and how to fabricate 3D nanostructures with it . However, irradiation products of solid anisole have not been properly identified yet.…”