ChEMS Seminar: Sub-5 Nanometer Patterning and Applications

Abstract: When feature sizes are smaller than certain critical dimensions, new phenomena come into play. By utilizing those new phenomena, devices with better performance, lower cost and even new functionality can be realized. I will present how to pattern sub-5 nm features and give some examples of applications. The key technologies that we use are nanoimprint lithography (NIL) and helium ion-beam lithography (HIBL). NIL is a cost-effective nanopatterning technology based on the mechanical deformation of a resist. It is capable of high-resolution, large-area, high-throughput and low-cost patterning. Moreover, it can be used to pattern 3-D nanostructures and on nonflat and flexible substrate. By combining NIL and HIBL (using HIBL to make high-resolution NIL molds), we have demonstrated high-resolution patterning down to 4 nm half pitch. Moreover, we also fabricated graphene nanoribbons with dense lines down to 5 nm half pitch using helium ion-beam lithography and demonstrated a bandgap of 88 meV. To pursue even higher resolution, we also invented a technology to fabricate nanogap structures with atomic-precision reliably and deterministically based on collapsible nanofingers fabricated using NIL. This technology has been used to probe gap plasmon down to 1 nm gap size. To demonstrate that applications relating to everyone’s daily life can be made by nanotechnology, a color-reflective display technology based on nano-photonics will also be presented.

Bio: Wei Wu graduated from Peking University with a bachelor's degree in physics in 1996 and received a doctorate in electrical engineering from Princeton University in 2003. He joined the Ming Hsieh Department of Electrical Engineering at the University of Southern California as an associate professor in January 2012. Before joining USC, he had worked as research associate, scientist and senior scientist at HP labs. His work includes the first nanoimprint-fabricated optical negative index meta-material at 1.55 micron range, the first optical modulation using negative index meta-material at near-IR, the first third-harmonic generation using meta-material, crossbar memory (i.e. memristor) and logic circuits with record-high densities, highly sensitive surface-enhanced Raman sensors fabricated using 3-D nanoimprint, the first room-temperature working single-electron memory and the first large-area bit-patterned magnetic media fabricated using nanoimprint. He coauthored 91 peer-reviewed journal papers, two book chapters and more than 100 conference presentations, including 14 keynote and invited presentations. He has 88 granted US patents and 29 pending applications. Half of them were also filed internationally. He has 6,871 total citations and an H-index of 42. He is a co-editor of Applied Physics A and an associate editor of IEEE Transactions on Nanotechnology. He also serves as an IEEE nanotechnology council 2015 and 2016 distinguished lecturer.  

Host: Regina Ragan