Manufacturing Bits: July 24
Firms Hatch Rattle Memory
The FOM Foundation and the Eindhoven University of Technology have devised a new technology called “rattle memory.” Researchers have demonstrated “magnetic domain-wall ratchet” memory, which potentially offers advantages compared to standard hard disks.
The bits in a nanowire have two possible magnetic directions, a 0 or a 1. Usually all of the bits are simultaneously set at either 0 or 1 during the construction as they reverse like compass needles.
By varying how the ions are fired across a nanowire, a repeating, saw-tooth-shaped energy landscape is created by the researchers. This, in turn, forces a domain wall, the boundary between bits, to move in a single direction under a variable magnetic field.
The force on the domain wall continually reverses. This is alternately pushed over the incline and then subsequently pushed back against the sharp edge. This one-way traffic of the domains is a movement comparable to that of a rattle or “ratchet.”
Researchers Find Self-healing Graphene
The University of Manchester and the Science and Technology Facilities Council (STFC) of the United Kingdom have demonstrated that graphene undergoes a self-repairing process to mend holes. This could give researchers an understanding of how metals interact with graphene, possibly enabling practical electronic devices in the future.
Graphene is a material that is made of sheets of carbon just one atom thick. In the research, nanoholes were etched in single-layer graphene sheets using an electron beam at room temperature. The graphene sheets were also exposed to metal impurities.
The results were captured using a scanning transmission electron microscope (STEM) at the SuperSTEM Laboratory at Daresbury in the U.K. The STEM allowed researchers to study the properties of materials one atom at a time. It demonstrated that metals can initiate the formation of holes in the graphene sheet, which could be detrimental to the properties of any graphene-based device.
Nanoholes, etched under an electron beam at room temperature in single-layer graphene sheets as a result of their interaction with metal impurities, are shown to heal spontaneously by filling up with either nonhexagon, graphene-like, or perfect hexagon 2D structures. Scanning transmission electron microscopy was employed to capture the healing process and study atom-by-atom the regrown structure. A combination of these nanoscale etching and reknitting processes could lead to new graphene tailoring approaches.
Results also showed that some of the holes that had been created during this process were actually mending themselves spontaneously using nearby loose carbon atoms to re-knit the graphene structure.
Quentin Ramasse, scientific director at SuperSTEM said: “The fact that graphene can heal itself under the right conditions may be the difference between a working device and a proof of concept without any real application. We may now have a way of not only drilling through graphene in a controlled fashion to sculpt it at the atomic level, but also to grow it back in new shapes. This adds a lot of flexibility to our nanotechnology toolbox and could pave the way to future technological applications”.
Sensors Reduce Water Consumption In IC Production
In chip production, surface preparation for a wafer typically consists of three steps: cleaning, rising and drying. The current practice is recipe-based and not controlled with real-time, in-line monitoring of the process steps. This, in turn, causes an unnecessary waste of chemicals, water and energy.
To help solve the problem, the Semiconductor Research Corp. (SRC), a research consortium, has developed new sensor and metrology technology that provides a reduction of water and energy in IC manufacturing.
The SRC Engineering Research Center (ERC) for Environmentally Benign Semiconductor Manufacturing at the University of Arizona (UA) has created a sensor-based approach that delivers a 30 percent savings in water and energy for ultra-clean production. “This technology can help to clear a big hurdle for semiconductor equipment and manufacturing companies,” said Farhang Shadman, lead researcher and the ERC director at UA for the SRC-funded research. “With this sensor application, we’re blunting the anticipated escalation of demand for more resources during surface preparation of the larger and more complex wafers.”
More Progress with DSA
The Massachusetts Institute of Technology (MIT) continues to advance its efforts in the emerging directed self-assembly (DSA) arena. Recently, MIT made cylindrical structures using DSA. Based on the same manufacturing techniques, MIT has devised several morphologies on a single substrate. A template consisting of a square symmetry array of posts produced a square-symmetry lattice of microdomains, which doubles the areal density of features.
—Mark LaPedus
Tags: Eindhoven University of Technology, FOM Foundation, grapheme, ratchet memory, rattle memory, Science and Technology Facilities Council, Semiconductor Research Corp., SuperSTEM Laboratory, University of Arizona, University of Manchester