Measurement of negative ion fluxes during DC reactive magnetron sputtering of Ti in Ar/O2 atmosphere using a magnetic-filtering probe

Abstract

The flux of negative oxygen ions in a dc reactive magnetron discharge has been measured using a specially developed magnetic-filtering probe. The gridded probe which operates as a retarding field analyzer has a magnetic filter attached to the front entrance to suppress plasma electrons entering the device. As a result, the fluxes of unmagnetized negative ions with energies of higher than ~10 eV can arrive to an ion collector and contribute to the detected probe current. During the oxide mode of Ti–Ar/O2 magnetron sputtering discharge, the measured negative ion flux is considered to be contributed by the sputtered O− ions generated at the target surface and the plasma O− ions created in the discharge volume. However, in specific discharge conditions, the sputtered ions are likely to dominate in the measured flux signal. As a result, the yield of the sputtered O− ions and associated energy flux can be examined. The magnetic-filtering probe could potentially be employed as a real-time diagnostic tool to monitor the sputtered O− flux as well as the oxide state of the target surface during reactive magnetron sputtering processes.