Nanofabrication of SOI-Based Photonic Waveguide Resonators for Gravimetric Molecule Detection

• Main Authors: Tony Granz, Julia Sophie Böke, Gerry Hamdana, Michael Martens, Arijit Misra, Stefan Preußler, Meinhard Schilling, Erwin Peiner, Thomas Schneider, Andreas Waag
• Format: Article
• Language: English
• Published: MDPI AG 2019-02-01
• Series: Proceedings
• Subjects: nanowaveguide; silicon photonics; optical communication; integrated optics; silicon technology
• Online Access: https://www.mdpi.com/2504-3900/2/13/1055

A silicon photonic microresonator comprising two curved vertical grating couplers and a single suspended Si nanowaveguide (NWG) is developed to investigate the giant enhanced Brillouin scattering in subwavelength NWGs caused by photon-phonon interaction. Finite element modelling based on COMSOL Multiphysics is conducted to optimize the critical device parameters (e.g., waveguide width, height, and length). As the smallest structures that need to be resolved are down to ~15 nm in size, electron-beam nanolithography is employed. In this case, dosage tests are carried out to minimize proximity charging effects during the nanopatterning of the silicon-on-insulator (SOI) surface, resulting in appropriate adaptive current area dosage distributions for the periodic gratings, couplers peripheral areas, and NWG, respectively. Furthermore, an enhanced inductively coupled plasma dry reactive ion etching (ICP-DRIE) process at a cryogenic temperature is used to realize smooth vertical sidewalls. Finally, buffered hydrofluoric acid (BHF)-based wet chemical etching is carried out to remove the buried oxide resulting in a suspended Si waveguide.