Mesurements of Thin Polymer Films Employing Split Post Dielectric Resonator Technique

Split post dielectric resonator (SPDR) operating at frequency about 10 GHz has been used for measurements of permittivity and dielectric loss tangent of thin polymer films deposited on a thin low loss polymer substrate. Uncertainty analysis and experiments have shown that it is possible to measure real permittivity and dielectric loss tangent of thin polymer films deposited on thin low loss dielectric substrates. Appropriate sensitivity of measurements can be achieved by stacking several substrates with deposited film together and thus creating multilayered dielectric structure.

1. INTRODUCTION

Split post dielectric resonators depicted in Fig. 1 have been widely used for measurements of PWB materials, substrates and thin ferroelectric films [1]–[3]. In this paper we discuss their applications for measurements of thin polymer films deposited on thin low loss polymer substrates. One of the major problems with accurate measurements of thin low permittivity films is to obtain sufficient sensitivity of measurements. This problem becomes critical if both film thickness and its permittivity are small. Polymer films can be deposited on various substrates, such as thin Teflon, Polyethylene or other low loss plastic foils, employing low temperature process. In order to increase sensitivity of measurements we proposed to create multilayered dielectric structure by stacking several substrates with deposited film together and perform measurements on such structure as it is shown in Fig. 2. Fig. 1 Schematic diagram of a split-post dielectric resonator Fig. 2. a) Cross section of multilayered structure created by stacked substrate foils with deposited thin polymer thin films. b) Stacked foils used as for reference measurements