Equivalent circuit fitting method for microwave characterisation of low-k dielectric thin films

Abstract

A new equivalent circuit fitting analysis scheme is proposed to analyse the measured data of test structures originally developed to characterise high-kappa dielectrics at frequencies up to 5 GHz (Zhengxiang et al 1998 IEEE Trans. Electron Devices 45 1811-6). It is compared to an extension of the analysis which can be used for high-kappa dielectrics at up to 50 GHz (Rundqvist et al 2004 Integr. Ferroelectr. 60 1-19). The proposed scheme focuses on the accurate characterisation of low-kappa dielectrics, which exhibit greater sensitivity to various parasitics. The scheme utilises the same concentric capacitor devices and measurement setup as the original method, maintaining the advantage of ease in fabrication of the original approach. The physical model employed in the analysis step of the original method, which tended to overestimate the dielectric permittivity, has been enhanced by incorporating fringing fields and a parasitic gap capacitance as circuit elements. The accuracy of the new approach is validated using experimental data, demonstrating its ability to more accurately determine the dielectric permittivity compared to the original method.