Matsuo Yamasaki

Characterization of a planar spiral inductor on a composite-resin low-impedance substrate and its application to microwave circuits

The Q-factors of planar spiral inductors built on a polyimide-SiO/sub 2/-Si substrate are characterized as a function of the polyimide thickness. We found that inductor quality as high as that on a GaAs-microwave and millimeter-wave integrated circuit (MMIC) requires a polyimide thickness of over 100 /spl mu/m, resulting in a Q-factor of over 17. The applicability of a low-impedance substrate was confirmed through the investigation of a novel RF-MCM in a face-up-type structure for cellular phone systems using a composite epoxy resin-metallic substrate. A fabricated power amplifier module exhibited 28.5-dBm output power and 16% power efficiency at 1.75 GHz.

High-frequency properties of SrTiO3 thin-film capacitors fabricated on polymer-coated alloy substrates

Low-temperature (200 °C) sputter deposition of SrTiO3 (STO) thin films by using ultrahigh-density ceramic target enabled us to fabricate capacitors on polyimide-isoindroquinazoline dione (PIQ)- or benzocyclobutene (BCB)-coated alloy substrates. Complex impedances of the capacitors were analyzed. Capacitances of the 0.01 mm2 area capacitors with 200-nm-thick STO films were around 22 pF and were not dependent on frequency up to 8 GHz. Leakage-current densities of the films were lower than 10−6 A/cm2 at an applied voltage of 10 V and dielectric loss tangents were lower than 10−6.