Manufacturing Bits: June 12
By Mark LaPedus
Directed self-assembly (DSA) continues to gather steam as an emerging patterning technology for next-generation devices. Massachusetts Institute of Technology (MIT), for example, has found a new way of making three-dimensional structures using self-assembling polymer materials. Using electron-beam lithography, MIT said they that have demonstrated an array of 10nm structures.
First, researchers from MIT created an array of posts on a substrate of silicon. Then, they coated the surface with block copolymers, which assembled into cylindrical structures. With DSA, MIT was able to set the spacing, angles, bends and junctions of the cylinders on the surface.
“Each of the two layers of cylinders can be independently controlled using these posts,” enabling 3-D devices, said Caroline Ross, the Toyota Professor of Materials Science and Engineering at MIT.
Craig Hawker, a professor of chemistry and biochemistry at the University of California at Santa Barbara, said: “The robustness and power of this approach may also lead to applications outside lithography and microelectronics, with impact in water purification, membranes and organic photovoltaics.” The same method could be used to create proteins or DNA molecules for use in developing biological detectors or drug-delivery systems, according to MIT.
MIT’s work was supported by the Semiconductor Research Corp. (SRC), the FENA Center, the Nanoelectronics Research Initiative, the Singapore-MIT Alliance, the National Science Foundation, Tokyo Electron Ltd. (TEL) and Taiwan Semiconductor Manufacturing Co. Ltd. (TSMC).
In a separate effort, with funding from the SRC, Stanford University has recently created contact hole patterns for a wide variety of logic and memory devices using DSA. The university demonstrated circuits at 22nm and projects the technology could enable devices down to 14nm.
“This is the first time that the critical contact holes have been placed with DSA for standard cell libraries of VLSI chips. The result is a composed pattern of real circuits, not just test structures,” said H.S. Phillip Wong, professor of electrical engineering at Stanford University. “This irregular solution for DSA also allows you to heal imperfections in the pattern and maintain higher resolution and finer features on the wafer than by any other viable alternative.”
Tags: directed self assembly, DSA, MIT, Stanford University, UC Santa Barbara