Probing 3D-printed nanostructures with high-speed atomic force microscopy

(Nanowerk News) Reporting their findings in ACS Applied Materials & Interfaces ("Probing the Morphology and Evolving Dynamics of 3D Printed Nanostructures Using High-Speed Atomic Force Microscopy"), researchers have implemented both in situ and online characterizations of 3D printed nanostructures by using a customized high-speed atomic force microscopy AFM (HS-AFM) inside the SEM chamber.
HS-AFM techniques have achieved a significantly improved temporal resolution, thus enabling both static and dynamic characterizations of the deposit. The increased imaging speed not only improves throughput but also allows for the first time the observation of evolving dynamics of the printed structures just after depositing.
Three-dimensional (3D) nanoprinting, a class of nanoscale additive manufacturing techniques, is attracting increasing interest. Achieving high fidelity multilayer material deposition has become one of the major challenges in focused electron beam induced deposition (FEBID) technology.
The slow image acquisition speed of AFMs in general, and in vacuum in particular, requires further efforts to achieve real combination of in situ measurement and nanofabrication.
In its new paper, the team demonstrates that it can achieve high fidelity in situ characterizations of a multistep focused electron beam induced deposition (FEBID) process by integrating their HS-AFM into the dual beam microscope.
This combination will enable the spatial information about the just deposited nanostructure to be directly used in controlling the FEBID process parameters for the following layers.
As a proof-of-concept test, the researchers achieved slice by slice additive tomography was achieved via in situ probing the growth of a nanostructure miniature Matterhorn replica.
In situ probing of the topography in three-dimensional additive patterning
In situ probing of the topography in three-dimensional additive patterning. (a) Contour map of the Matterhorn, including 25 height lines (b) SEM image of the finished miniature Matterhorn replica. (c) Layer series showing the process of 25-layer patterning. The first 7 AFM images are taken after every 3 layers being deposited, while the eighth image contains information on the remaining 4 layers. The scale bar of the image is 1 µm. (d) Line profiles illustrating the miniature Matterhorn growth. (e) Height distribution of the imaged layers. (f) Photograph of the Matterhorn in Switzerland (photographer, Andrew Bossi; source, Wikimedia). (g) Three-dimensional AFM image of the Matterhorn replica. (© ACS) (click on image to enlarge)
Furthermore, by coordinating operations of HS-AFM and FEBID, the team could shed light on evolving physical properties (such as mechanical stability) that happen at short time scales post deposition.
"We believe that this in situ and online monitoring approach will ramp up the thorough understanding of FEBID parameters and thus enable highly reliable fabrication of nanostructures with strict morphological requirements," the authors conclude their report.
Michael Berger By – Michael is author of three books by the Royal Society of Chemistry:
Nano-Society: Pushing the Boundaries of Technology,
Nanotechnology: The Future is Tiny, and
Nanoengineering: The Skills and Tools Making Technology Invisible
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