Conformal thin film packaging for sic sensor circuits in harsh environments
In this investigation sputtered silicon carbide annealed at 300°C for one hour is used as a conformal thin film package. A RF magnetron sputterer was used to deposit 500 nm silicon carbide films on gold metal structures on alumina wafers. To determine the reliability and resistance to immersion in harsh environments, samples were submerged in gold etchant for 24 hours, in BOE for 24 hours, and in an O2 plasma etch for one hour. The adhesion strength of the thin film was measured by a pull test before and after the chemical immersion, which indicated that the film has an adhesion strength better than 108 N/m2; this is similar to the adhesion of the gold layer to the alumina wafer. MIM capacitors are used to determine the dielectric constant, which is dependent on the SiC anneal temperature. Finally, to demonstrate that the SiC, conformal, thin film may be used to package RF circuits and sensors, an LC resonator circuit was fabricated and tested with and without the conformal SiC thin film packaging. The results indicate that the SiC coating adds no appreciable degradation to the circuits RF performance.
PECVD Silicon Carbide as a Chemically-Resistant Thin Film Packaging Technology for Microfabricated Antennas
This paper describes an effort to develop microfabricated planar antennas that utilize a plasma enhanced chemical vapor deposition (PECVD) based silicon carbide (SiC) thin film packaging technology to provide chemical resistance. The antennas are coplanar waveguide fed dual frequency folded slot antennas fabricated on alumina substrates that utilize a self matching impedance technique. The PEVCD SiC thin film was deposited at 300degC at a chamber pressure of 900 mTorr and a power level of 100 W. The SiC film thickness was 450 nm. The antennas exhibit a return loss better than -15 dB at 5 and 7 GHz before and after SiC deposition. The gain of the antennas is 3 dB at 5 and 7 GHz before and after SiC deposition. The SiC-coated antennas were submerged into Au etchant for over a 24 hr period with no degradation in RF performance or physical integrity
The power of negativity : selected writings on the dialectic in Hegel and Marx
Part 1 The Philosophic Moment of Marxist-Humanism Part 2 Studies in Hegalian and Marxian Dialectics, 1956-63 Part 3 Theory and Practice at a Turning Point, 1964-71 Part 4 After Philosophy and Revolution: Hegel's Absolutes and Marx's Humanism, 1972-81 Part 5 The Changed World and the Need for Philosophic New Beginnings, 1982-87