Deposition of Iron Nitride Soft Magnetic Thin Films with Giant Saturation Magnetization by Sputtering type Plasma Source

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In this research, deposition of iron nitride thin films with large saturation magnetization was attempted by means of a sputtering type plasma source. The sputtering type plasma source has a facing target type high rate sputtering source, and ions extracted from the plasma source can be deposited directly on the substrate, although some amounts of neutral atoms are also deposited on the substrate.Improvement of the plasma source was achieved by changing the ion extraction method from multi-holes to single extraction hole method, and by an increase of the strength of the plasma confinement magnetic field. As a result, the films can be deposited at an incident ion density as high as 1 mA/cm^2, and the life of the target could be prolonged by more than one order.The iron nitride films were deposited at various incident ion energies. The amount of ion incident to the substrate during deposition was also changed. Following results are obtained.(1)The incidence of ions with large kinetic ene … More rgy suppresses the crystal growth in the film. The nitrogen content in the film also decreases as the incident ion energy increases. These iron nitride films deposited at large ion energy has excellent soft magnetic properties (saturation magnetization : 2.0-2.2 T, coercive force : <1.0 Oe).(2)Nitrogen content in the film can be controlled by adjusting the nitrogen partial gas pressure and the bias voltage of the substrate. However, the film with Fe_<16>N_2 single phase that has a large saturation magnetization above 2.8 T could not be obtained on glass slide substrate in this research.(3)A decrease in the amount of ion incident to the substrate promotes a crystal growth in the film. This result suggests that the ions incident to the substrate increase the density of nucleation sites, which results in the suppression of the crystal growth in the film.In this research, it can be clarified that the control of the amount and energy of the incident ions to the substrate is very important to obtain the iron nitride films with desired properties. However, the deposition condition to obtain the Fe_<16>N_2 single phase film is still unclear. Less