UPPER-BOUND FREQUENCY FOR MEASURING MM-WAVE-BAND DIELECTRIC CHARACTERISTICS OF THIN FILMS ON SEMICONDUCTOR SUBSTRATES

The upper-bound frequency is estimated to be approximately 60 GHz, from the measurement on thin film capacitors of SrTiO3 (STO) deposited by the electron-cyclotron-resonance (ECR) sputtering. The upper-bound frequency is found to be defined by the parallel stray element located between the capacitor and the series stray element in the lead electrode. This parallel stray element was not included in our previous study. By changing stray circuit configuration from parallel-series to parallel-series-parallel, the upper-bound can be successfully extended from 60 GHz to 110 GHz. The measurable capacitance range is approximately two orders of magnitude (from 0.01 pF to 1 pF) for a 50-GHz upper-bound. And it is one order of magnitude for a 110-GHz upper-bound. It is also demonstrated that the ECR sputtered STO thin films can be used in a wide frequency range up to 110 GHz.