The new method — developed by MIT visiting doctoral student Amir Tavakkoli of the National University of Singapore, along with two other graduate students and three professors in MIT's departments of Electrical Engineering and Computer Science (EECS) and Materials Science and Engineering (DMSE) — is described in a paper published this August in the journal Advanced Materials; the paper is available online now.
The process is closely related to a method the same team described last month in a paper in Science, which makes it possible to produce three-dimensional configurations of wires and connections using a similar system of self-assembling polymers.
In the new paper, the researchers describe a system for producing arrays of wires that meet at right angles, forming squares and rectangles. While these shapes are the basis for most microchip circuit layouts, they are quite difficult to produce through self-assembly. When molecules self-assemble, explains Caroline Ross, the Toyota Professor of Materials Science and Engineering and a co-author of the papers, they have a natural tendency to create hexagonal shapes — as in a honeycomb or an array of soap bubbles between sheets of glass.
For example, an array of tiny ball bearings in a box "tends to give a hexagonal symmetry, even though it's in a square box," Ross says. "But that's not what circuit designers want. They want patterns with 90-degree angles" — so overcoming that natural tendency was essential to producing a useful self-assembling system, she says.
The team's solution creates an array of tiny posts on the surface that guides the patterning of the self-assembling polymer molecules. This turns out to have other advantages as well: In addition to producing perfect square and rectangular patterns of tiny polymer wires, the system also enables the creation of a variety of shapes of the material itself, including cylinders, spheres, ellipsoids and double cylinders. "You can generate this astounding array of features," Ross says, "with a very simple template."
Karl Berggren, an associate professor of electrical engineering at MIT and a co-author of the paper, explains that these complex shapes are possible because "the template, which is coated so as to repel one of the polymer components, causes a lot of local strain on the pattern. The polymer then twists and turns to try to avoid this strain, and in so doing rearranges on the surface. So we can defeat the polymer's natural inclinations, and make it create much more interesting patterns."
This system can also produce features, such as arrays of holes in the material, whose spacing is much closer than what can be achieved using conventional chip-making methods. That means it can produce much more closely packed features on the chip than today's methods can create — an important step in the ongoing efforts to pack more and more electronic components onto a given microchip.
"This new technique can produce multiple [shapes or patterns] simultaneously," Tavakkoli says. It can also make "complex patterns, which is an objective for nanodevice fabrication," with fewer steps than current processes. Fabricating a large area of complex circuitry on a chip using electron-beam lithography "could take several months," he says. By contrast, using the self-assembling polymer method would take only a few days.
That's still far too long for manufacturing a commercial product, but Ross explains that this step needs to be done only once to create a master pattern, which can then be used to stamp a coating on other chips in a very rapid fabrication process.
The technique could extend beyond microchip fabrication as well, Ross says. For example, one approach to the quest to pack ever-greater amounts of data onto magnetic media such as computer hard disks is to use a magnetic coating with a very fine pattern stamped into it, precisely defining the areas where each bit of data is to be stored. Such fine patterning could potentially be created using this self-assembly method, she says, and then stamped onto the disks.
Tavakkoli and Ross' colleagues in this work are DMSE doctoral students Adam Hannon and Kevin Gotrik, DMSE professor Alfredo Alexander-Katz and EECS professor Karl Berggren. The research, which included work at MIT's Nanostructures Laboratory and Scanning-Elecrron-Beam Lithography facility, was funded by the Semiconductor Research Corporation, the Center on Functional Engineered Nano Architectonics, the National Resources Institute, the Singapore-MIT Alliance, the National Science Foundation, the Taiwan Semiconductor Manufacturing Company and Tokyo Electron
Written by David Chandler, MIT News Office
Caroline McCall | EurekAlert!
Gelatine instead of forearm
19.04.2017 | Empa - Eidgenössische Materialprüfungs- und Forschungsanstalt
Computers create recipe for two new magnetic materials
18.04.2017 | Duke University
The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
Two researchers at Heidelberg University have developed a model system that enables a better understanding of the processes in a quantum-physical experiment...
Glaciers might seem rather inhospitable environments. However, they are home to a diverse and vibrant microbial community. It’s becoming increasingly clear that they play a bigger role in the carbon cycle than previously thought.
A new study, now published in the journal Nature Geoscience, shows how microbial communities in melting glaciers contribute to the Earth’s carbon cycle, a...
20.04.2017 | Event News
18.04.2017 | Event News
03.04.2017 | Event News
21.04.2017 | Physics and Astronomy
21.04.2017 | Health and Medicine
21.04.2017 | Physics and Astronomy