Terahertz One-Port De-Embedding Method for Extracting Dielectric Constant of SiO₂ in Standard CMOS

This article presents a one-port de-embedding method for extracting dielectric constant of SiO₂ in standard complementary metal-oxide-semiconductor (CMOS) at terahertz frequencies. Instead of extracting dielectric constant using absolute parameters from one cavity resonator, the presented method extracts key information from relative differences of three designated cavity resonators. By doing so, this method gains a unique de-embedding technique that can remove the effect of the feeding network and other repeatable errors, which simplifies the calibration and increases measurement accuracy. Furthermore, compared with conventional resonant methods requiring widely swept data or complex data processing, the proposed method only requires f_L and Q_L, which can be directly measured even from a narrow frequency band. Therefore, it reduces the measurement requirement and lowers the detuned error. For validation, both simulations and experiments are carried out at 140, 300, and 450 GHz. The testing samples are fabricated using commercial 0.18-μm and 65-nm CMOS processes and measured by a terahertz on-wafer measurement setup. Results show full on-chip compatibility, greater simplicity, and good de-embedding effects, making this method suitable for on-chip dielectric characterizations.