Effects from the Thin Metallic Substrate Sandwiched in Planar Multilayer Microstrip Lines

Abstract

This paper studies the dispersion characteristics of open multilayer microstrip lines with a thin highly-conductive metallic substrate using the spectral domain approach. From the numerical results, it is found that, in both lossy (metal-insulator-silicon structure such as Si-SiO2) and lossless configurations (thin metal between lossless dielectric microstrip line), at the low frequency range, this thin metallic substrate can excite slow waves. And accordingly the frequency dependent transmission-line characteristics of interconnects, such as propagation constant, attenuation and the characteristic impedance, can change remarkably with the existence of the thin metallic substrate.