Wide band frequency and in situ characterization of high permittivity insulators (high-k) for high-speed integrated passives

High permittivity insulators (high-k) are progressively introduced in high-speed integrated passives and devices in order to optimize circuits performances. However, high-k properties are expected to vary with frequency as relaxation and resonance mechanisms occur. It is necessary to analyze and evaluate high-k behavior from DC to microwave frequency. Real permittivity (k or εr) and losses (ε″) extraction is required over a wide band of frequency to select the most suitable insulator. The proposed method enables the characterization of as deposited thin planar dielectrics integrated below a copper coplanar transmission line. By adjusting software modeling to experimental measurements from 40 MHz up to 40 GHz, the complex permittivity of the high-k material is determined. The simplicity of the test structure, the in situ technique and the investigation protocol enable the method to check a large variety of high-k dielectrics. Results of Si3N4 and Ta2O5 insulators are presented in this paper.