High Rate Sputter Deposition Method for Superconductors

Solar Associates proposes to develop a sputtering process for YBCO superconductors. The energy spectrum of atoms depositing on the substrate will be controlled to an optimum range between 20 and 50 eV. Such energy control will remove the harmful effects of negative oxygen ion bombardment. A sputter deposition system using a surrogate rotating cylindrical magnetron (cf. patent 5,405,517) will be used to develop methods to increase and optimize the plasma capture magnetic field. With high magnetic fields, the critical deposition parameters of plasma voltage and deposition pressure will be substantially lowered. The range of energy of arriving adatoms at the depositing phosphor film can then be more closely controlled than has been previously possible. The process also allows precise in-situ control of stoichiometry and dopant levels. The net result will be the ability to deposit superconductors on-axis. Additionally, lower deposition and annealing temperatures should be possible. The method uses no toxic gases. The goal of the Phase I effort will be to fabricate a test deposition system to demonstrate that low plasma voltages and low sputter pressures are possible and to demonstrate control of the arriving particle energy spectrum. Chromium film resistivity will be used as a measure of the effect of energy control on thin film quality.