PT Unknown
AU Finkel, M
   Thierschmann, HR
   Galatro, L
   Katan, AJ
   Thoen, DJ
   de Visser, PJ
   Spirito, M
   Klapwijk, TM
TI Branchline and directional THz coupler based on PECVD SiNx-technology
SE 41st IRMMW-THz
PY 2016
DI 10.1109/IRMMW-THz.2016.7758586
DE microstrip; fixtures; coplanar waveguides; couplers; standards; probes; dielectrics
AB A fabrication technology to realize THz microstrip lines and passive circuit components is developed and tested making use of a plasma-enhanced chemical vapor deposition grown silicon nitride (PECVD SiNx) dielectric membrane. We use 2 μm thick SiNx and 300 nm thick gold layers on sapphire substrates. We fabricate a set of structures for thru-reflect-line (TRL) calibration, with the reflection standard implemented as a short through the via. We find losses of 9.5 dB/mm at 300 GHz for a 50 Ohm line. For a branchline coupler we measure 2.5 dB insertion loss, 1 dB amplitude imbalance and 21 dB isolation. Good control over the THz lines parameters is proven by similar performance of a set of 5 structures. The directional couplers show -14 dB transmission to the coupled port, -24 dB to the isolated port and -25 dB in reflection. The SiNx membrane, used as a dielectric, is compatible with atomic force microscopy (AFM) cantilevers allowing the application of this technology to the development of a THz near-field microscope.
ER