Precise fabrication of semiconducting carbon nanotubes (CNTs) into densely aligned evenly spaced arrays is required for ultrascaled technology nodes. We report the precise scaling of inter-CNT pitch using a supramolecular assembly method called spatially hindered integration of nanotube electronics. Specifically, by using DNA brick crystal-based nanotrenches to align DNA-wrapped CNTs through DNA hybridization, we constructed parallel CNT arrays with a uniform pitch as small as 10.4 nanometers, at an angular deviation <2° and an assembly yield >95%.
Selective
area atomic layer deposition (SA-ALD) offers the potential to replace
a lithography step and provide a significant advantage to mitigate
pattern errors and relax design rules in semiconductor fabrication.
One class of materials that shows promise to enable this selective
deposition process are self-assembled monolayers (SAMs). In an effort
to more completely understand the ability of these materials to function
as barriers for ALD processes and their failure mechanism, a series
of SAM derivatives were synthesized and their structureproperty
relationship explored. These materials incorporate different side
group functionalities and were evaluated in the deposition of a sacrificial
etch mask. Monolayers with weak supramolecular interactions between
components (for example, van der Waals) were found to direct a selective
deposition, though they exhibit significant defectivity at and below
100 nm feature sizes. The incorporation of stronger noncovalent supramolecular
interacting groups in the monolayer design, such as hydrogen bonding
units or pi–pi interactions, did not produce an added benefit
over the weaker interacting components. Incorporation of reactive
moieties in the monolayer component that enabled the polymerization
of an SAM surface, however, provided a more effective barrier, greatly
reducing the number and types of defects observed in the selectively
deposited ALD film. These reactive monolayers enabled the selective
deposition of a film with critical dimensions as low as 15 nm. It
was also found that the selectively deposited film functioned as an
effective barrier for isotropic etch chemistries, allowing the selective
removal of a metal without affecting the surrounding surface. This
work enables selective area ALD as a technology through (1) the development
of a material that dramatically reduces defectivity and (2) the demonstrated
use of the selectively deposited film as an etch mask and its subsequent
removal under mild conditions.
We demonstrate a bottom-up/top-down combined method for the fabrication of horizontally suspended, well-oriented and size-controlled Si nanowire arrays. Mechanical beamlike structures composed of multiple ordered arrays consecutively linked by transversal microspacers are obtained by this method. Such structures are used to investigate the mechanical elasticity of the nanowire arrays by atomic force microscopy. Our results point out important differences in the morphology and mechanical behavior of the fabricated nanowire-based structures with respect to equivalent bulk material structures.
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