Low-Damage Reactive Ion Etching of Nanoplasmonic Waveguides with Ultrathin Noble Metal Films

• Main Authors: Alina A. Dobronosova, Anton I. Ignatov, Olga S. Sorokina, Nikolay A. Orlikovskiy, Michail Andronik, Aleksey R. Matanin, Kirill O. Buzaverov, Daria A. Ezenkova, Sergey A. Avdeev, Dimitry A. Baklykov, Vitaly V. Ryzhkov, Aleksander M. Merzlikin, Aleksander V. Baryshev, Ilya A. Ryzhikov, Ilya A. Rodionov
• Format: Article
• Language: English
• Published: MDPI AG 2019-10-01
• Series: Applied Sciences
• Subjects: nanoplasmonic waveguide; plasmonic nanocircuitry; low-damage alumina etch; multilayer waveguide; noble metals etching; multilayer stack etching
• Online Access: https://www.mdpi.com/2076-3417/9/20/4441

Nanoplasmonic waveguides utilizing surface plasmon polaritons (SPPs) propagation have been investigated for more than 15 years and are now well understood. Many researchers make their efforts to find the best ways of using light and overcoming the speed limit of integrated circuits by means of SPPs. Here, we introduce the simulation results and fabrication technology of dielectric-metal-dielectric long-range nanoplasmonic waveguides, which consists of a multilayer stack based on ultrathin noble metals in between alumina thin films. Various waveguide topologies are simulated to optimize all the geometric and multilayer stack parameters. We demonstrate the calculated propagation length of L_prop = 0.27 mm at the 785 nm wavelength for the Al₂O₃/Ag/Al₂O₃ waveguides. In addition, we numerically show the possibility to eliminate signal cross-talks (less than 0.01%) between two crossed waveguides. One of the key technology issues of such waveguides’ nanofabrication is a dry, low-damage-etching of a multilayer stack with extremely sensitive ultrathin metals. In this paper, we propose the fabrication process flow, which provides both dry etching of Al₂O₃/Au(Ag)/Al₂O₃ waveguides nanostructures with high aspect ratios and non-damage ultrathin metal films patterning. We believe that the proposed design and fabrication process flow provides new opportunities in next-generation photonic interconnects, plasmonic nanocircuitry, quantum optics and biosensors.