Using a novel self-assembly approach, the Johannes Gutenberg University Mainz and the Max Planck Institute for Polymer Research have created a new flexible mineral inspired by deep-sea sponges. The technology could one day enable futuristic body armor.
Researchers recreated sponge spicules using calcium carbonate and a protein of a sponge. Spicules are tiny spike-like structures found in many organisms. They deter predators because they are hard, sharp and prickly.
Researchers devised synthetic spicules using silicatein-α, which is responsible for the biomineralization of silicates in sponges. Researchers used silicatein-α to guide the self-assembly of calcite spicules, which are similar to the spicules of a calcareous sponge.
The self-assembled spicules, 10 to 300 um in length and 5 to 10 μm in diameter, are composed of aligned calcite nanocrystals. The spicules are initially amorphous, but transform into calcite within months.
The synthetic spicules are elastic. This feature is linked to a high protein content. With nano-thermogravimetric analysis, researchers measured the organic content of a single spicule to be 10% to 16%. In addition, the spicules exhibit wave-guiding properties even when they are bent.
Since the 1960s, the industry has been trying to commercialize phase change memory (PCM). Sometimes called PCRAMs, PCM exploits the phase change behavior of chalcogenide materials. In theory, PCRAMs are a possible replacement for today’s solid-state memory devices.
Micron Technology and Samsung Electronics have recently shipped low-density PCM devices for limited applications. But in general, PCM is difficult to scale and expensive to manufacture.
Power consumption is another problem with PCM. The Korea Advanced Institute of Science and Technology (KAIST) has developed PCM technology at a power-consumption level below 1/20th of its present level. To accomplish this feat, KAIST has devised a novel approach using directed self-assembly (DSA).
Researchers used a block copolymer to form a thin nanostructured SiOx layer, which locally blocks the contact between a heater electrode and a phase change material. Using this approach, the writing current is decreased fivefold, as the occupying area fraction of SiOx nanostructures is increased from a fill factor of 9.1% to 63.6%.
Using DSA, researchers were able to reduce power faster than expected. “This is a very good example that self-assembled, bottom-up nanotechnology can actually enhance the performance of electronic devices. We also achieved a significant power reduction through a simple process that is compatible with conventional device structures and existing lithography tools,” said Keun-Jae Lee, a professor of KAIST, on Nanowerk’s Web site.
The scanning electron microscope (CD-SEM) has been used in the fab for decades as a means to measure the critical dimensions of complex structures.
Some believe the CD-SEM will soon run out of steam. One of the problems with the CD-SEM is contamination, which could become a showstopper for measurements at the nanometer scale.
The National Institute of Standards and Technology (NIST) is looking to prolong the life of the CD-SEM, by developing cleaning and other improvements to the existing technology.
Charged particle beam-induced contamination in the SEM is the issue. There is a buildup of carbonaceous material on the surface of the sample, where the ions or electrons are focused. This, in turn, results in characteristic dark patterns, making repeatable quantitative measurements difficult or impossible.
In the 1990s, NIST tested a prototype low-energy (20 Watt) plasma unit. The system, designed by XEI Scientific, was able to clean the CD-SEM by flooding it with oxygen plasma. Later, NIST collaborated with the IBSS Group to develop a modified plasma-cleaning device. That device works in a wider vacuum range and also has up to 99 Watts of power.
New research indicates that the electron bombardment itself during extended measurements can act as a cleaning process for a variety of samples. With the research, NIST and others devised the so-called Contamination Specification. These are steps that SEM users can take to determine whether their instruments need to be cleaned and how to implement an effective cleaning process.
“We know how to get the instruments clean, and we know how to clean the samples,” said András Vladár of the Semiconductor and Dimensional Metrology Division (SDMD), on NIST’s Web site. “We learned that when you clean it, the instrument can remain contamination free for months unless a dirty sample is used.”