Manufacturing Bits: Aug. 1

Magnetic chips
HRL Laboratories—an R&D venture between Boeing and General Motors—has been awarded a contract to develop a new class of magnetic integrated components.

HRL has received the award from the Defense Advanced Research Project Agency (DARPA) under the Magnetic, Miniaturized, and Monolithically Integrated Components (M3IC) program. The goal is to develop new magnetic materials, designs and devices for use in RF and millimeter-wave applications.

In current monolithic microwave ICs, magnetic materials have not been used. It is too hard to integrate and the ability to scale the technology is also challenging.

Looking to overcome the challenges, HRL is developing what it calls a Large Area Nanoferrite Assembly (LANA) technology. Using epitaxial deposition techniques, the technology enables the monolithic integration of magnetic devices on wafers at room temperature. The technology can handle any wafer sizes and materials, including silicon or gallium-nitride (GaN).

More specifically, HRL is developing hexaferrite nanoparticle synthesis technology and the assembly of these nanoparticles to produce magnetic components on wafers. One possible device for this technology is a circulator, which combines simultaneous radio transmission and reception in a single antenna.

“Our approach combines a binder-free nanoparticle assembly process with traditional patterning techniques on semiconductor wafers,” said Shanying Cui, a scientist in HRL’s Sensors and Materials Laboratory, on the venture’s Web site. “The typical way would be to grow magnetic material using epitaxy, which is very challenging for thick films and large wafer processes.”

Florian Herrault from HRL’s Microelectronics Laboratory, added: “Through this program we hope to advance the state-of-the-art of these materials along with demonstrating integration approaches on microwave-integrated circuit wafers. By combining millimeter wave and magnetic materials with monolithic integration, the resulting circuitry will enable faster production, more compact subsystems, and dramatically lower cost for Department of Defense uses.”

Magnetic metrology
Using a new X-ray metrology technique, Paul Scherrer Institute (PSI), ETH Zurich and the University of Glasgow have taken three-dimensional images of the magnetic moments in structures down to 100nm.

The research could provide the industry with a better understanding of magnetic materials. Researchers mapped magnetic structures using hard X-ray magnetic tomography. This technology resembles computer tomography (CT) used in the medical field. With magnetic X-ray tomography, though, several X-ray images are taken from many different directions with a small angle in-between. The measurements were carried out using a synchrotron light source at PSI.

Swirling internal magnetic structure (Graphics: Paul Scherrer Institute/Claire Donnelly)

This imaging technique, called ptychography, uses computer calculations and reconstruction algorithms to form the final 3D map of the magnetization. With the technology, scientists looked inside a gadolinium-cobalt magnet. They mapped the arrangement of the magnetic moments. This can be described as tiny magnetic compass needles inside the material. The needles define a magnetic structure.

Representation of a Bloch point. A Bloch point contains a magnetic singularity at which the magnetization abruptly changes its direction. (Graphics: Paul Scherrer Institute/Claire Donnelly)

In the images, researchers found intertwining patterns and Bloch points. At Bloch points, magnetic needles quickly change direction. “Up to now, imaging magnetism and magnetic patterns at this small scale could only be done in thin films or on the surfaces of objects,” said Laura Heyderman, a researcher at PSI and professor at ETH Zurich, on the organization’s Web site. “We really feel like we are diving inside the magnetic material, seeing and understanding the 3D arrangement of the tiny magnetic compass needles.”

Semi-metals
Tulane University and others have discovered a new magnetic topological semi-metal material.

In the R&D stage for years, topological materials carry electrons as if they have no mass. They are similar to the properties of photons.

The experiments were conducted at the National High Magnetic Field Laboratory (MagLab). They were conducted within MagLab’s DC Field Facility on a 31-tesla magnet system. “The recent discoveries of topological materials—a new class of quantum materials—hold great promise for use in energy-saving electronics,” said Zhiqiang Mao from Tulane. “The result is expected to improve fundamental understanding of the fascinating properties of topological semi-metals.”