Manufacturing Bits: Sept. 11
Sea Squirt To Enable Chips
The University of Aberdeen’s Marine Biodiscovery Centre and the University of St. Andrews devised a new type of chip based on the molecules from a sea squirt sourced at the Great Barrier Reef.
Sea squirts are immobile filter feeders that live on the ocean floor. Scientists also are exploring sea squirts and other natural resources from the sea to create new pharmaceuticals for the treatment of diseases such as cancer.
The work specifically focused on the molecule patellamide. This was discovered from the sea squirt Lissoclinum patella, which was found in the Great Barrier Reef. Patellamide is a peptide, which is a short polymer of amino acid monomers linked by bonds.
Scientists devised a process for redesigning the molecules into simple electronic components. Its production uses clean and green biological processes.
“This project is looking at a greener, more sustainable alternative—making transistors from single molecules sourced from nature,” said Marcel Jaspars, professor of organic chemistry at the University of Aberdeen and director of the institution’s Marine Biodiscovery Centre.
“Developing a computer chip from single molecules sourced from nature has a number of benefits. It is greener to produce as we can essentially ‘grow’ the parts required for the new ‘patellamide’ computer chip in a test tube, meaning it would be significantly more environmentally-friendly than creating silicon computer parts,” he said on the university’s Web site. “It would result in a smaller, more compact computer as the computer chip would have an array of single patellamide molecules meaning overall the computer chip would be more compact.”
Needle Beams For Optical Interconnects
Researchers have demonstrated a new type of light beam that propagates without spreading outwards, thereby reducing the signal loss for on-chip optical systems.
Harvard, the Laboratoire Interdisciplinaire Carnot de Bourgogne and CNRS devised the so-called “needle beam.” The technology could enable a new class of microprocessors.
The needle beam is devised from a special class of quasiparticles, dubbed plasmons. A plasmon results from the quantization of plasma oscillations. Needle beam itself is a term that describes a cosine-Gauss plasmon beam, which propagates in a tight confinement with a nanostructured metal surface.
esearchers led by Federico Capasso at SEAS demonstrated a cosine-Gauss plasmon beam, dubbed a "needle beam," that propagates without diffraction. The advance may assist the development of ultrafast microprocessors. (Source: Harvard)
In the Harvard-led research, the metallic stripe that carries surface plasmons could replace copper electrical interconnects in today’s chips. It could also pave the way for optical interconnects. The problem with optical interconnects is that the waves spread laterally during propagation. The phenomenon, known as diffraction, reduces the portion of the signal that can be detected.
“We have made a major step toward solving this problem by discovering and experimentally confirming the existence of a previously overlooked solution of Maxwell’s equations that govern all light phenomena,” said Federico Capasso, the Robert L. Wallace Professor of Applied Physics and the Vinton Hayes Senior Research Fellow in Electrical Engineering at Harvard.
“The solution is a highly localized surface plasmon wave that propagates for a long distance, approximately 80 microns in our experiments, in a straight line without any diffraction,” Capasso said on Harvard’s Web site.
Built-In Laser ICs
The Paul Scherrer Institute (PSI), ETH Zurich and the Politecnico di Milano have demonstrated that germanium can function as a laser material in chips under certain conditions.
In effect, researchers say built-in germanium lasers could make chips run faster. As a laser material, germanium with silicon could form the basis for chips in which information would be transferred partially by light.
Researchers have demonstrated that germanium must be put under strain by an external force to turn it into a laser material. In the lab, a direct-gap gain up to 850 cm-1 at 0.74 eV was measured and modeled in optically pumped germanium-on-silicon layers for photoexcited carrier densities of 2.0×1020 cm-3.
The gain spectra are correlated to carrier density via plasma-frequency determinations from reflection spectra, according to researchers. The key concept is optical data transfer between the different cores on the chip, said Hans Sigg, a PSI scientist. “This means partially transferring information inside a chip with the aid of laser pulses, which would significantly speed up the information exchange,” he said on the PSI Web site.
PSI doctoral student Peter Friedli added: “We stimulate the material by means of a powerful laser and simultaneously observe the changes occurring using infra-red radiation from the SLS (Swiss Light Source). To do this, we used the fact that these light pulses are only 100 picoseconds long, allowing us to follow the relevant processes in the material; that is, the behavior of electrons at different points in time.”
Hybrid Metrology
The National Institute of Standards and Technology (NIST) has refined its hybrid metrology technique for use in measuring nanometer-sized objects.
This approach is enables the precise measurement of three-dimensional transistors and other structures at 16nm and beyond, according to NIST.
First described in 2009, NIST’s hybrid metrology is a combination of scanning techniques and statistical analysis. Initially, NIST created a library of simulated data based on typical chip feature dimensions using atomic force microscopy (AFM), scatterometry and other technologies.
This tiny silicon pillar, measuring less than 100 nanometers along any of its sides, is the sort of computer chip feature that manufacturers now can measure more precisely with NIST’s hybrid metrology method, which can reduce the nagging uncertainties that have long plagued industry’s measurement efforts. (Source: NIST)
NIST also implemented a statistical method called Bayesian analysis. This is a concept of probability and belongs to the category of evidential probabilities. In any case, this method reduced the uncertainty in some of the measurements by a factor of three.
For years, fabs have used scatterometry techniques, which are used to determine the dimensions on the semiconductor wafer. AFM is a high-resolution type of scanning probe microscopy. “Maybe scatterometry tells you the width of an object is 40 nanometers, but it’s plus or minus three nanometers, a relatively large variance. Making things worse, the total uncertainty usually increases when measurement techniques are combined, making our vision even hazier,” said NIST scientist Richard Silver, in a statement on NIST’s Web site.
“In essence, if you’ve got a really small uncertainty in your AFM measurement, but a big one in your optical measurements, the final uncertainty will end up even smaller than either of them,” Silver said. “IBM and GlobalFoundries have already begun developing the technique since we first described it at a 2009 conference, and they are improving their measurements using this hybrid approach.”
—Mark LaPedus
Tags: CNRS, ETH Zurich, Germanium, Harvard, Laboratoire Interdisciplinaire Carnot de Bourgogne, lasers, National Institute of Standards, needle beam, NIST, optical interconnects, Paul-Scherrer Institute, Politecnico di Milano, Sea Squirt, University of Aberdeen, University of St. Andrews