Batch production of large-area double-sided YBa₂Cu₃O_7−δthin films by DC magnetron sputtering

Abstract

Using a novel DC magnetron sputtering system, high quality YBa2Cu3O7−δ (YBCO) thin films were deposited on both sides of twelve pieces of 3-inch LaAlO3(00l) single crystal substrates in one batch. This sputtering system has a rotatable disc sample holder with the LaAlO3 substrates being positioned in the middle of upper and lower YBCO targets. These two sputter guns are arranged to simultaneously deposit YBCO thin films on both sides of the substrate. The rotatable sample holder is an important approach to large scale deposition of high quality YBCO thin films. In this manner, the sputtered species can diffuse well around the substrates during one rotation cycle. Furthermore, the anode is installed in the inner of rotatable disc sample holder to avoid negative ion bombardment. Thus, a good uniformity over the whole area for all the films has been realized. The full-width at half-maximum (FWHM) values of the (005) rocking curves typically range from 0.49° to 0.56°. The superconducting critical temperatures fall in the range of 89–90 K and the critical current densities are between 3.75 and 4.0 MA cm−2 at 77 K. The microwave surface resistance, RS (77 K, 10 GHz), of the YBCO thin films range typically from 0.56 to 0.71 mΩ, which make these films suitable for microwave applications.