Electroplated thick-film cobalt platinum permanent magnets

The material and magnetic properties of multi-micron-thick (up to 6μm) L10 CoPt magnetic films electroplated onto silicon substrates are investigated as candidate materials for integration in silicon-based microsystems. The influence of various process conditions on the structure and magnetic properties of electroplated CoPt thick-films is studied in order to better understand the complex process/structure/property relationships associated with the electroplated films. Process variables studied here include different seed layers, electroplating current densities (ranging from 25–200mA/cm2), deposition times (up to 60min), and post-deposition annealing times and temperatures. Analyses include film morphology, film thickness, composition, surface roughness, grain size, phase volume fractions, and L10 ordering parameter. Key correlations are found relating process and structure variations to the extrinsic magnetic properties (remanence, coercivity, squareness, and energy product). Strong hard magnetic properties (Br ~0.8T, Hci ~800kA/m, squareness close to 0.9, and BHmax of 100kJ/m3) are obtained for films deposited on Si/TiN/Ti/Cu at current densities of 100mA/cm2, pH of 7, and subsequently annealed at 675°C for 30min. •CoPt films plated up to 6μm thick on silicon substrates.•A1 to L10 phase transformation by annealing in forming gas.•Various process–structure–property relationships explored.•Key results: Br ~0.8T, Hci ~800kA/m, squareness 0.9, and BHmax ~100kJ/m3.