Broadband Characterization of Thin Dielectrics Using Heterolayer and Monolayer MIM Capacitors

Abstract

Characterization of the complex permittivity and loss tangent of a dielectric is essential for broadband and microwave applications. Non-resonant methods are applicable over a wide frequency range. However, they can get less accurate dielectric properties than resonant methods. To overcome this limitation, in this study, a new non-resonant method is proposed to extract properties of thin dielectric accurately by measuring the reflection coefficient of two metal-insulator-metal (MIM) capacitors. First, we designed the heterolayer and monolayer MIM capacitor structures that are needed for high accuracy and broadband characterization. Second, the characterization method was formulated by analyzing the two structures by equivalent circuit modeling and verified via a 3D full–wave electromagnetic simulation. Finally, by setting HfO₂ and Al₂O₃ as target dielectrics, heterolayer and monolayer capacitors were fabricated, and their reflection coefficients were measured using a vector network analyzer in the range of 0.1–67 GHz—a broadband range scarcely considered in prior studies on non-resonant methods. The results of applying the measurement data to the proposed method indicate that a high-accuracy characterization of the complex permittivity and loss tangent of the high-k dielectrics, HfO₂ and Al₂O₃, in the broadband frequency range is achieved.