Received PACS numbers: 75.50.Vv, 5µm thick NdFeB films have been sputtered onto 100 mm Si substrates using high rate sputtering (18 µm/h). Films were deposited at ≤ 500°C and then annealed at 750°C for 10 minutes. While films deposited at temperatures up to 450°C have equiaxed grains, the size of which decreases with increasing deposition temperature, the films deposited at 500°C have columnar grains. The out-of-plane remanent magnetization increases with deposition temperature, reaching a maximum value of 1.4 T, while the coercivity remains constant at about 1.6 T. The maximum energy product achieved (400 kJ/m 3 ) is comparable to that of high-quality NdFeB sintered magnets.NdFeB thin films with excellent hard magnetic properties have been prepared by sputtering 1 and Pulsed Laser Deposition. 2 Out-of-plane texture was induced by depositing the films onto heated substrates in both 1-step (directly crystallized) 1,2 and 2-step (crystallized during a post-deposition anneal) 3,4,5 processes. Thick films (≥5 µm) of such high performance hard magnetic materials have potential applications in magnetic MEMS (Micro Electro Mechanical Systems). 6 Their integration into MEMS requires the use of preparation techniques which can produce high deposition rates over large areas. In addition, the use of substrates which are compatible with today's MEMS technology (i.e. Si) is necessary for the exploitation of such materials. So far, the only group which has reported the successful growth of textured NdFeB thick films by high rate sputtering (≈30 µm/h) used metallic substrates. 3 in this letter, we report on the preparation and analysis of 5µm thick NdFeB films deposited on 100 mm Si substrates using high rate sputtering. The film's magnetic properties compare with those of high-quality sintered NdFeB magnets.{Ta (100 nm) / NdFeB(5 µm) / Ta (100 nm)} films were deposited onto (001) oriented Si substrates (diameter = 100 mm) at a rate of 18 µm/hour by triode sputtering of square targets of surface area 100 mm x 100 mm (note that the film thickness is reduced to 4 µm at the edge of the 100 mm wafer). The nominal composition of the NdFeB target was Nd 16.8 Fe 74.7 BB 8.5 .During deposition, the substrate was either "cold" (no power to substrate heater, though the substrate temperature gradually rises during deposition, eventually reaching a temperature of about 230°C) or fixed at a temperature in the range 300 -500°C. Full wafers were annealed at 750°C for 10 minutes. Structural characterization was carried out using high resolution Scanning Electron Microscopy (LEO Gemini 1530, equipped with In-Lens and Quadrant Back Scattering (QBSD) detectors as well as Energy Dispersive X-ray Analyzer (EDX)) andx-ray diffraction (Co radiation). For cross-sectional imaging, the samples were simply fractured while for plane-view imaging they were lightly polished to remove the Ta capping

No abstract

No abstract

The magnetic microstructure of thermomechanically processed (die-upset) melt-spun NdFeB magnets with different degrees of texture in thermally demagnetized and in dc-demagnetized states has been investigated systematically using magnetic force microscopy. An isotropic magnetic microstructure with a fine contrast on a scale between 200 and 400 nm has been clearly observed in the hot-pressed precursor in the thermally demagnetized state. Broad and well-pronounced interaction domains with lateral expansion over many individual grains have been found in the magnet with a maximum degree of texture. The crystallographic texture of this magnet has been analyzed by electron backscatter diffraction using a high-resolution scanning electron microscope. On a mesoscopic scale, most of the crystallites have a misorientation smaller than 10 deg, yielding macroscopically a high value of remanent magnetization (1.34 T). The presence of a threshold value in dependence of the size of the interaction domains on the degree of texture has been identified. The alignment of individual crystallites strongly influences the formation and the size of interaction domains.

5µm thick SmCo films were deposited onto Si substrates using triode sputtering. A study of the influence of deposition temperature (T dep ≤ 600°C) on the structural, magnetic and mechanical properties has shown that optimum properties (highest degree of in-plane texture, maximum in-plane coercivity and remanence (1.3 and 0.8 T, respectively), no film peel-off) are achieved for films deposited at the relatively low temperature of 350°C. This temperature is compatible with film integration into Micro-Electro-Mechanical-Systems (MEMS). The deposition rate was increased from 3.6 to 18 µm/h by increasing the surface area of the target from 7 to 81 cm 2 . Mechanically stable films could be prepared by deposition onto prepatterned films or deposition through holes in a mask.