High rate deposition of thick piezoelectric ZnO films using a new magnetron sputtering technique

Abstract

ZnO films were prepared on glass substrates with a new reactive magnetron sputtering technique using a zinc target. A solenoid coil around a bell jar was used to cause an increase in the parallel component of the leakage lines to the target surface. Highly oriented ZnO films (c‐axis orientation) were fabricated on the glass substrates. The deposition rate increases with increasing discharge current, and it attains 15 μm/h for (O₂ 50%:Ar50%), 11 μm/h for (81.5%:18.5%), and 9 μm/h for 100% oxygen. These films were obtained at a 500‐mA discharge current and a 0.2‐Torr total gas pressure. Resistivities of the films were 10⁶–10⁹ Ω cm. A piezoelectric coupling constant of thick ZnO films (∼30 μm) was obtained by measuring a frequency response of transducer impedance near the fundamental resonance frequency of the interdigital electrode. Experimental results were about 80% of the theoretical values.