Deposition of Fe-N films by means of an opposed targets sputtering type plasma source

Abstract

Synthesis of Fe-N thin films were attempted by means of an opposed targets sputtering type plasma source. In this film preparation technique, both ions and neutral particles which are extracted from the plasma source are deposited on the substrate directly. Film deposition rate changes with substrate bias voltage Vs and takes a maximum value at a Vs around −30 V. This is mainly due to the increase in the amount of incident ions as the Vs decreases from 20 V to −30 V. The ion ratio in the deposited particles is estimated to be about 1/3 from the changes in the deposition rate with Vs. The increase in the amount of incident ions and in their energy suppresses the growth of the crystallites in the film significantly, which results in the decrease in coercive force of the films. The films deposited at a proper condition has a saturation magnetization of about 1700 emu/cc, coercive force below 0.8 Oe, and permeability at 1 MHz above 3000.