Researchers create chips with self assembling rectangles

The team used a system that produced arrays of wires that met at right angles, forming squares and rectangles. While these shapes are the basis for most microchip circuit layouts, they are difficult to produce through self assembly. The system creates an array of tiny posts on the surface that guides the patterning of the self assembling polymer molecules. As well as producing perfect square and rectangular patterns of polymer wires, it also enables the creation of a variety of shapes of the material itself, including cylinders, spheres, ellipsoids and double cylinders. 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," said Karl Berggren, associate professor of electrical engineering at MIT. "The polymer then twists and turns to try to avoid this strain, and in so doing rearranges on the surface" The researchers say that the system can also produce features, such as arrays of holes in the material, with much closer spacing than what can be usually be achieved. This means it can produce much more closely packed features on a chip than today's methods. "This new technique can produce multiple [shapes or patterns] simultaneously," said MIT visiting doctoral student Amir Tavakkoli. It can also make "complex patterns, which is an objective for nanodevice fabrication," with fewer steps than current processes. Where fabrication would usually take several months, the self assembling polymer method would only take a few days. Although that's still too long for manufacturing a commercial product, the researchers say that this step only needs to be done once to create a master pattern, which can then be used to stamp a coating on other chips in a very rapid fabrication process.