S-parameters-based extraction of effective dielectric constant in transmission lines on multilayer substrates

Methodology for extracting an effective dielectric constant of transmission lines on multilayer substrates from measured or simulated S-parameters data, using "on-chip" test structures has been demonstrated. The methodology consists of: 1) building "on-chip" interconnect structures usually implemented by calibration and de-embedding procedures in microwave "on-wafer" test and measurements - transmission lines, stubs and pad launchers; 2) extracting the effective dielectric constant from the characteristic impedance and propagation constant of these structures, fully described by measured or EM-simulated S-parameters. The demonstrated methodology is applicable for evaluation of dielectric and semiconductor multilayer substrates, both with lossy and lossless characteristics, over a broad frequency band. Another advantage is implementation of short transmission line structures with physical dimensions much smaller than quarter wavelength of the highest investigated band frequency, thus preserving valuable chip area in the test structures and being compatible with some of the calibration TRL elements.