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Nanophotonics is living up to the hype. The study of light on the nanoscale might have been a ‘buzzword’ within optics circles a couple of years ago, but this tiny science is now moving away from the world of theoretical science and new research facilities are popping up in laboratories around the world.

And, with it, nanophotonics brings a myriad of new nano-prefixed buzzwords, including nanocapacitors, nanoforests, nanorice and nanoshells. But the real buzz is around the applications that using light as a tool on the submicron scale could open up.

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Applied scientists at Harvard University in collaboration with researchers from the German universities of Jena, Gottingen, and Bremen, have developed a new technique for fabricating nanowire photonic and electronic integrated circuits that may one day be suitable for high-volume commercial production.

Fabrication technique could yield low-cost, scalable nanowire photonic and electronic circuits

Spearheaded by graduate student Mariano Zimmler and Federico Capasso, Robert L. Wallace Professor of Applied Physics and Vinton Hayes Senior Research Fellow in Electrical Engineering, both of Harvard’s School of Engineering and Applied Sciences (SEAS), and Prof. Carsten Ronning of the University of Jena, the findings will be published in Nano Letters. The researchers have filed for U.S. patents covering their invention.

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Future nanomanufacturing processes will rely on two basic principles: a combination of chemical synthesis and self-assembly on one hand and robotic nanofabrication on the other. While the former is a controlled ‘natural’ process relying on chemistry and self-organization principles of nature (read more: How falling spaghettis could lead to more complex nanotechnology self-assembly), the latter will be an industrial process similar in concept to today’s automated manufacturing assembly lines.

Micromanufacturing

Continue reading ‘A Gripping Tale for Nanomanufacturing’ »

In response to the electronics industry’s rallying cry of “smaller and faster,” the next breakthroughs in the electronics size barrier are likely to come from microchips and data storage devices created out of novel materials such as organic molecules and polymers. With innovative measurement techniques and new ways to position the molecules, NIST researchers reported at the March Meeting of the American Physical Society how they have improved manipulation of so-called block copolymers—polymers made of a mixture of two or more different molecule building blocks that are tethered at a junction point—which can form arrays of tiny dots that could be used as the basis for electronic components that pack terabytes (1000 gigabytes) of memory in something as small as a pack of gum.

One of the challenges in polymer nanotechnology is how to control their self-assembly—a hard-to-control process for materials which require precision. An important recent NIST accomplishment has been in developing accurate measurements of thin film polymeric nanostructure in 3-D. (Ironically, while determining atomic structure is well-established, measuring the slightly larger internal structure of the polymers—on the order of 10 to 20 nanometers—is much harder.) Ron Jones, together with colleagues from NIST, the University of Maryland and IBM, has used NIST’s neutron scattering and reflectivity facility to deflect neutrons off block copolymer films from many different angles. By combining the many 2-D neutron scattering pictures into a single composite scattering pattern, this technique provides the first quantitative method for imaging the 3-D internal structure of thin film polymeric nanostructures using neutron scattering—a crucial tool to see if the nanoscale polymer structures are in their required positions.

NIST researchers also have developed new insights on how best to nudge these self-assembling material into those positions. August Bosse will report on computer simulations that model how the polymers assemble when they are placed on templates lined with troughs separated by crests. When a heated zone is swept across the template, the polymer molecules assemble into almost defect free, well-aligned lines faster over the entire template, an important feature for nanotech manufacturing applications. Sangcheol Kim (working with a team that included researchers from the University of Maryland and IBM) has found that changing the surface chemistry of the template by making some parts hydrophillic and some parts hydrophobic also can elegantly control the dimension of the block-copolymer pattern relative to the chemical template.

Continue reading ‘Copolymers Block Out New Approaches To Microelectronics’ »

Courtesy Atsushi Asano, Cornell University

While not quite on the nanoscale, an average human sperm on average is about 0.055 mm long, sperm have provided inspiration for how to power nano-sized devices. Energy to power the sperm tail (flagellum) comes from the mitochondria, the power stations of the cell, while the rear section of the tail or ‘principal piece’ gets it’s energy from glycolysis, the direct breakdown of glucose to produce energy. It’s this process that has inspired researchers at the Cornell NanoScale Science and Technology Facility to try and mimic this process to provide a power source for nanodevices.

In sperm, the 10 enzymes required for glycolysis are attached to scaffolding proteins in the sperm tail, holding them in place in a unique conformation. Scientists engineered and tethered 3 of the 10 proteins to a gold surface covered in nickel ions, whilst retaining the enzymes activity. Researchers are now looking to extend the project to include all 10 protens necessary to complete a nano ‘power supply’.

Gaithersburg, MD — Scientists at the National Institute of Standards and Technology (NIST) have made the first direct measurements of the infinitesimal expansion and collapse of thin polymer films used in the manufacture of advanced semiconductor devices. It’s a matter of only a couple of nanometers, but it can be enough to affect the performance of next-generation chip manufacturing. The NIST measurements, detailed in a new paper,* offer a new insight into the complex chemistry that enables the mass production of powerful new integrated circuits. The smallest critical features in memory or processor chips include transistor “gates.” In today’s most advanced chips, gate length is about 45 nanometers, and the industry is aiming for 32-nanometer gates. To build the nearly one billion transistors in modern microprocessors, manufacturers use photolithography, the high-tech, nanoscale version of printing technology. The semiconductor wafer is coated with a thin film of photoresist, a polymer-based formulation, and exposed with a desired pattern using masks and short wavelength light (193 nm). The light changes the solubility of the exposed portions of the resist, and a developer fluid is used to wash the resist away, leaving the pattern which is used for further processing.

Exactly what happens at the interface between the exposed and unexposed photoresist has become an important issue for the design of 32-nanometer processes. Most of the exposed areas of the photoresist swell slightly and dissolve away when washed with the developer. However this swelling can induce the polymer formulation to separate (like oil and water) and alter the unexposed portions of the resist at the edges of the pattern, roughening the edge. For a 32-nanometer feature, manufacturers want to hold this roughness to at most about two or three nanometers.

Industry models of the process have assumed a fairly simple relationship in which edge roughness in the exposed “latent” image in the photoresist transfers directly to the developed pattern, but the NIST measurements reveal a much more complicated process. By substituting deuterium-based heavy water in the chemistry, the NIST team was able to use neutrons to observe the entire process at a nanometer scale. They found that at the edges of exposed areas the photoresist components interact to allow the developer to penetrate several nanometers into the unexposed resist. This interface region swells up and remains swollen during the rinsing process, collapsing when the surface is dried. The magnitude of the swelling is significantly larger than the molecules in the resist, and the end effect can limit the ability of the photoresist to achieve the needed edge resolution. On the plus side, say the researchers, their measurements give new insight into how the resist chemistry could be modified to control the swelling to optimal levels.

Continue reading ‘Nanoscale Details Of Photolithography Process In Semiconductor Manufacturing Revealed’ »