Thin films of YBa2Cu3O7−δ were sequentially grown on both sides of 3 in. diameter LaAlO3 substrates by a single-source MOCVD technique to facilitate the fabrication of double-sided high temperature superconductor microwave devices. YBCO films on both sides of the LaAlO3 substrates had thicknesses greater than 4000 Å, Tc’s of 87–88.5 K, and microwave surface resistances as low as 23 mΩ at 94 GHz and 77 K (scaling to 260 μΩ at 10 GHz). It was found that the substrate temperature, brought to the desired value by radiant heating, played a critical role in the deposition of very low surface resistance YBCO films. Microwave bandpass filters with a 19-pole forward coupled configuration were fabricated from these films. The filters showed excellent performance with dissipation losses as low as 0.5 dB.

A novel super-conducting slow-wave transmission line has been prepared by overlaying a superconducting coplanar waveguide with normal metal crossbars. The crossbars increase the energy storage along the transmission line, reducing the line's group velocity allowing for shorter delay lines. Additionally, the cross-sectional dimensions of the line are smaller than typical transmission line structures, allowing for a further reduction of delay line size. Measurements show a group velocity of about 0.12 the speed of light with low dispersion, a 25 OMEGA characteristic impedance, and moderate transmission loss. Because the group velocity is largely independent of any properties of the superconductor, these transmission lines exhibit excellent temperature stability and delay reproducibility.

The deposition of thin films of superconducting YBa/sub 2/Cu/sub 3/O/sub 7-x/ onto substrates of up to 3-in diameter by an integrated off-axis sputtering is reported. The substrate is located above the center of an 8-in-diameter YBCO planar target, and, in conjunction with a negative ion shield, negative ion effects are avoided. A large radiant heater provides backside, noncontact heating of the bare substrates. YBCO films have been grown on polished 1-cm/sup 2/ MgO and LaAlO/sub 3/ substrates with T/sub c/>or=90 K, J/sub c/>or=2.5*10/sup 6/ A/cm/sup 2/ at 77 K, and microwave surface resistance R/sub S/<0.4 m Omega at 77 K and 10 GHz. The films have a very smooth surface morphology. Uniformity data for LaAlO/sub 3/ substrates are less than +or-5% in R/sub s/. Thickness uniformity results for 3-in substrates indicate less than 10% variation. The growth of epitaxial insulating films for use with YBCO films and application of the YBCO films in microwave devices are briefly discussed.<>

TiN thin films were deposited by reactive sputtering onto Si substrates. TiO2 films were formed by subsequent oxidation of the TiN films, using either conventional furnace heating or rapid thermalprocessing (RTP). The materials properties of the resulting films were characterized by x-ray diffraction and Rutherford backscattering, and indicate conversion of the TiN to fully-oxidized rutile TiO2 by a diffusion-limited process. Electrical measurements of the insulating properties of the TiO2 films indicated a relative dielectric constant greater than 100, although the leakage current was greater than optimum. A fully in-situ process for the fabrication of microcapacitors is proposed, which involves the sputter deposition of TiN, the formation of TiO2 by RTP, and the deposition of a top TiN counterelectrode. This can be carried out under conditions that are compatible with Si microelectronic device processing.