Nd–Fe–B Film Magnets With Thickness Above 100 Deposited on Si Substrates

Although increase in thickness of a Nd-Fe-B film magnet is indispensable to provide a sufficient magnetic field, it was difficult to suppress the peeling phenomenon due to the different values of a linear expansion coefficient for a Si substrate and a Nd-Fe-B film even if a buffer layer such as a Ta film was used. In this report, it was confirmed that a control of the microstructure for pulsed laser deposition-fabricated Nd-Fe-B films enabled us to increase the thickness up to approximately 160 μm without a buffer layer on a Si substrate. Namely, we found that the precipitation of the Nd element at the boundary of Nd-Fe-B grains together with the triple junctions due to the composition adjustment is effective in suppressing the destruction of the samples through an annealing process. The magnetic properties of the prepared films were comparable with those of previously reported ones deposited on metal substrates. Although the mechanism is under investigation, the above-mentioned film had stronger adhesive force compared with that of a sputtering-made film. Resultantly, no deterioration of mechanical together with magnetic properties could be observed after a dicing process.