Application of 60 mm φ superconducting bulk magnet to magnetron sputtering

Abstract

We constructed the planar magnetron sputtering apparatus using a c-axis oriented single-domain Sm123 bulk superconductor with 60 mm in diameter as a very powerful magnet in place of an ordinary Nd–Fe–B magnet. A high magnetic field of 4.2 T at the surface of the superconductor coupled with a high target voltage of maximum 6 kV enabled us to discharge even at pressure of 1 × 10 −3 Pa. A target-to-substrate distance of 300 mm was successfully employed under low pressures of 10 −2–10 −3 Pa to make the deposition of almost contamination-free films feasible. The simulation software (JMAG) was used to optimize the magnetic circuit configurations. The simulations could reproduce well the distribution of the magnetic field above the target measured by a three-axial Hall sensor. The discharging characteristics of Cu, Ni and Fe targets in the pressure range over 10 −1–10 −3 Pa were studied under different target voltages. The deposition rates of 0.063 nm/s (or 38 Å/min) and 0.013 nm/s (or 8 Å/min) were achieved for Cu and Fe targets with 3 mm in thickness, respectively, under the Ar pressure of 6.6 × 10 −2 Pa (or 4.9 × 10 −4 Torr).