Optical interconnect on CMOS ICs made with Compact Silicon nitride
building blocs and photodetector
R. Orobtchouk1, B. Han1, P.R.A. Binetti2, S. Jeannot3, X.J.M. Leijtens3, T. Benyattou1, JM.
Laboratoire de Physique de la Matière, Institut National des Sciences Appliquées de Lyon ,
Bât. Blaise Pascal , 7 avenue Jean Capelle 69621 Villeurbannne cedex, France
COBRA Research Institute, Technische Universiteit Eindhoven, Postbus 513, 5600 MB
Eindhoven, The Netherlands
STMicroelectronics, 850 rue Jean Monnet, 38921 Crolles, France
CEA-DRT/LETI, 17 rue des Martyrs, 38054 Grenoble Cedex 9, France
According to the ITRS roadmap, optical interconnects have been identified as a promising
alternative for avoiding the bottleneck in the global interconnection of the future generation
of CMOS ICs. Results on modelling and optical characterization of the basics compact
building blocks made on a Si3N4 strip waveguide (0.4µm thick by 0.8 µm width) technology (
bends and MMI) used for the routing of an optical clock signal will be shown. Basic elements
exhibit low losses of 1.5 dB/cm, 0.1 dB/bend and 0.5 dB at =1.55 µm respectively for the
waveguide, a 15 µm radius bend and a 1 by 2 MMI. A first 1 by 16 optical distribution has
been demonstrated and will be presented. We present also the modelling of a compact guide
to guide coupler of 16 µm length used for the coupling to a III-V photodetector (PD) on top of
the optical layer by wafer bonding. Optimization of the PD leads to a predicted 3dB
bandwidth of 25 GHz. The optical coupler could be used also for the coupling to a III-V
source that provide a full integration of an optical link.
This work is supported by STREP European program "Picmos"