An nucleus microscope–based lithography complement for patterning materials during sizes as tiny as a singular nanometer could be used to emanate and investigate materials with new properties
UPTON, NY—The ability to settlement materials during ever-smaller sizes—using electron-beam lithography (EBL), in that an electron-sensitive element is unprotected to a focused lamp of electrons, as a primary method—is pulling advances in nanotechnology. When a underline distance of materials is reduced from a macroscale to a nanoscale, particular atoms and molecules can be manipulated to dramatically change element properties, such as color, chemical reactivity, electrical conductivity, and light interactions.
In a ongoing query to settlement materials with ever-smaller underline sizes, scientists during a Center for Functional Nanomaterials (CFN)—a U.S. Department of Energy (DOE) Office of Science User Facility during Brookhaven National Laboratory—have recently set a new record. Performing EBL with a scanning delivery nucleus microscope (STEM), they have patterned skinny films of a polymer poly(methyl methacrylate), or PMMA, with particular facilities as tiny as one nanometer (nm), and with a spacing between facilities of 11 nm, agreeable an areal firmness of scarcely one trillion facilities per block centimeter. These record achievements are published in a Apr 18 online book of Nano Letters.
“Our idea during CFN is to investigate how a optical, electrical, thermal, and other properties of materials change as their underline sizes get smaller,” pronounced lead author Vitor Manfrinato, a investigate associate in CFN’s nucleus microscopy organisation who began a plan as a CFN user while completing his doctoral work during MIT. “Until now, patterning materials during a singular nanometer has not been probable in a controllable and fit way.”
Commercial EBL instruments typically settlement materials during sizes between 10 and 20 nanometers. Techniques that can furnish higher-resolution patterns need special conditions that possibly extent their unsentimental application or dramatically delayed down a patterning process. Here, a scientists pushed a fortitude boundary of EBL by installing a settlement generator—an electronic complement that precisely moves a nucleus lamp over a representation to pull patterns designed with mechanism software—in one of CFN’s aberration-corrected STEMs, a specialized microscope that provides a focused nucleus lamp during a atomic scale.
“We converted an imaging apparatus into a sketch apparatus that is able of not usually holding atomic-resolution images though also creation atomic-resolution structures,” pronounced coauthor Aaron Stein, a comparison scientist in a electronic nanomaterials organisation during CFN.
Their measurements with this instrument uncover a scarcely 200 percent rebate in underline distance (from 5 to 1.7 nm) and 100 percent boost in areal settlement firmness (from 0.4 to 0.8 trillion dots per block centimeter, or from 16 to 11 nm spacing between features) over prior systematic reports.
The team’s patterned PMMA films can be used as stencils for transferring a drawn single-digit nanometer underline into any other material. In this work, a scientists combined structures smaller than 5 nm in both lead (gold palladium) and semiconducting (zinc oxide) materials. Their built bullion palladium facilities were as tiny as 6 atoms wide.
Despite this record-setting demonstration, a organisation stays meddlesome in bargain a factors that still extent resolution, and eventually pulling EBL to a elemental limit.
“The fortitude of EBL can be impacted by many parameters, including instrument limitations, interactions between a nucleus lamp and a polymer material, molecular measure compared with a polymer structure, and chemical processes of lithography,” explained Manfrinato.
An sparkling outcome of this investigate was a fulfilment that polymer films can be patterned during sizes most smaller than a 26 nm effective radius of a PMMA macromolecule. “The polymer bondage that make adult a PMMA macromolecule are a million repeating monomers (molecules) long—in a film, these macromolecules are all caught and balled up,” pronounced Stein. “We were astounded to find that a smallest distance we could settlement is good next a distance of a macromolecule and nears a distance of one of a monomer repeating units, as tiny as a singular nanometer.”
Next, a organisation skeleton to use their technique to investigate a properties of materials patterned during one-nanometer dimensions. One early aim will be a semiconducting element silicon, whose electronic and visual properties are likely to change during a single-digit nanometer scale.
“This technique opens adult many sparkling materials engineering possibilities, tailoring properties if not atom by atom, afterwards closer than ever before,” pronounced Stein. “Because a CFN is a inhabitant user facility, we will shortly be charity a first-of-a-kind nanoscience apparatus to users from around a world. It will be unequivocally engaging to see how other scientists make use of this new capability.”
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