New Technique for Making Nanoelectronic Devices

An international team of researchers demonstrated how control over materials on the nano scale can be extended to create complex patterns important in the production of nanoelectronics. Previously, a research team from the University of Wisconsin-Madison demonstrated a lithographic technique for creating patterns in the chemistry of polymeric materials used as templates for nanomanufacturing. They deposited a film of block copolymers on a chemically patterned surface such that the molecules arranged themselves to replicate the underlying pattern without imperfections.

That technique works well for creating templates that are neatly ordered in periodic arrays. But, according to the researchers, one of the challenges of nanofabrication is integrating these self-assembling materials into existing manufacturing strategies. This new technique directs the assembly of blends of block copolymers and homopolymers on chemically nanopatterned substrates. The result is the creation of structures with non-regular geometries. The fine control over structure dimensions has, therefore, been potentially harnessed, afforded by self-assembling materials, to allow for the production of complex nanoelectronic devices. That kind of control is critical if computer architects are to continue advancing by Moore's Law.

Current manufacturing processes employing chemically amplified lithography techniques achieve dimensions as small as 50 to 70 nm, but that technology might not be extendable as feature dimensions shrink below 30 nm.

By merging the latest principles of lithography and self-assembly block-copolymer techniques, researchers at UW-Madison and the Paul Scherrer Institute in Switzerland developed a hybrid approach that maximizes the benefits and minimizes the limitations of each approach to nanomanufacturing.
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(A) Schematic of the directed self-assembly process used to orient block copolymers. A thin film (~45 nm) of block copolymer is deposited on a patterned chemical surface and annealed such that the block copolymer phase separates into ordered domains. (B) The phase segregated block copolymer forms disordered “fingerprint” features on an unpatterned surface (left image) and ordered features such as 45° and 135° bends on patterned chemical surfaces (middle and right images).