Accurate Evaluation Technique of Complex Permittivity for Low-Permittivity Dielectric Films Using a Cavity Resonator Method in 60-GHz Band

In order to realize modern millimeter-wave applications, the accurate value of complex permittivity of low-permittivity dielectric films with excellent characteristics are needed by circuit designers and material developers. However, there are few accurate measurement methods for dielectric films in the millimeter-wave region. In this paper, an accurate evaluation technique for thin dielectric films using a novel V-band cavity in the 60-GHz band is proposed on the basis of a cavity resonator method. The novel V-band cavity with small excitation holes, which does not affect the resonant electromagnetic fields, is designed and fabricated. The six kinds of thin dielectric film were measured by the proposed technique using the novel cavity. The measured results and the uncertainty analysis validate the accuracy and the usefulness of the proposed method. Moreover, it was verified that this technique can evaluate thin samples with thicknesses of 10 μm or more.