Evaporatively deposited Co-MgF₂ granular materials for thin-film inductors

Co-MgF₂ granular thin films prepared by thermal evaporation are reported. The fabricated materials show promise as high-frequency, low-loss cores for microfabricated magnetic devices in microprocessor power delivery applications. Transmission electron microscopy (TEM) reveals Co grains of about 3.2 nm embedded in a MgF₂ matrix 1 to 2 nm wide. Films were prepared with 20% to 89% volume cobalt at substrate temperatures between -21°C and 311°C. Good soft magnetic properties in a range of 40% to 55% volume cobalt with high DC resistivity of 500 μΩ-cm to 100 Ω-cm are measured for films deposited at room temperature. Low intrinsic coercivity, H_ci of 0.76 Oe and susceptibility, χ of 26 in the easy axis direction with quality factor, Q over 100 and saturation flux density, B_s of 0.7 T are obtained