Influence of Buffer/Protective Layers on the Structural and Magnetic Properties of SmCo Films on Silicon

Abstract

Integration of samarium-cobalt hard magnets on silicon requires buffer/protective layers that can enhance the magnetic properties of the magnet while preserving its structure and chemical composition after post-annealing treatments needed for the formation of the magnetically hard phase. In this work, a comparison of samarium-cobalt films for five different buffer/protective layers, namely, Ti, W, TiW, Ta, and Cr, and two different annealing temperatures, 650 °C and 750 °C, is presented. Depending on materials and annealing temperatures, magnetic properties such as saturation and coercivity of the SmCo film can be finely tuned. We show that coercivity up to 3.65 T or saturation magnetization up to 0.95 T can be reached by proper choice of the relevant process parameters: deposition temperature, material for the buffer/protective layer, and annealing temperature. Such value of coercivity is among the highest found in the literature for thin films of SmCo.