High rate deposition of magnetic material by gas flow sputtering

For different applications like thin film sensors or microactuators soft and hard magnetic films are required to create and guide the magnetic flux. In many cases, the required thickness of the coatings is well above 10 µm. For the preparation of coatings various techniques are used. In this paper we will present gas flow sputtering as a high potential method for high rate preparation of soft and hard magnetic coatings. The preparation conditions were varied and the influence of gas flow, working pressure, deposition temperature and substrate bias were investigated. In the field of soft magnetic films NiFe (81/19) was investigated. After optimization of the deposition parameters, growth rates exceeding 50 µm · h-1 were realized. The permeability µr was also tailored to higher values. Actual results showed µr values higher than 240 for a 10 µm thick coating. For films sputtered at 300°C the coercitivity Hc of was below 340 A·m-1. As a hard magnetic material CoxSmy was investigated. Since the stoichiometry of the target was Co:Sm = 80:20 at.-%, CoSm coatings with mainly Co5Sm were prepared. The angular dependence of the coercivity Hc and remanence Br were investigated. The resulting coercitivity of the films was up to 1 220 kA·m-1 even with a high content of residual oxygen in the films. Deposition rates of 85 µm·h-1 could be realized.