We present a performance analysis of passive THz components based on Microstrip transmission lines with a 2-m-thin plasma-enhanced chemical vapor deposition grown silicon nitride (PECVD SiNx) dielectric layer. A set of thru-reflect-line calibration structures is used for basic transmission line characterizations. We obtain losses of 9 dB/mm at 300 GHz. Branchline hybrid couplers are realized that exhibit 2.5-dB insertion loss, 1-dB amplitude imbalance, and 26-dB isolation, in agreement with simulations. We use the measured center frequency to determine the dielectric constant of the PECVD SiNx, which yields 5.9. We estimate the waferto-wafer variations to be of the order of 1. Directional couplers are presented which exhibit 12-dB transmission to the coupled port and 26 dB to the isolated port. For transmission lines with 5-m-thin silicon nitride (SiNx), we observe losses below 4 dB/mm. The thin SiNx dielectric membrane makes the THz components compatible with scanning probe microscopy cantilevers allowing the application of this technology in on-chip circuits of a THz near-field microscope.
