Deposition of thick Co-rich CoPtP films with high energy product for magnetic microelectromechanical applications

We report the development of Co-rich CoPtP films of thicknesses up to 82 mu m for use in magnetic MEMS applications. These films have been deposited using a combination of pulse-reverse plating with the addition of stress-relieving additives to the bath. The films were electroplated on sputtered Cu/Ti seed layer on silicon with an optimized thickness of 100/20 nm. The composition, crystalline structure, grain size and magnetic properties of the CoPtP films of varying thickness are compared and analyzed. The 3-mm-thick CoPtP film showed a columnar structure and strong perpendicular anisotropy. This film shows a perpendicular coercivity of 2150 Oe, a remanence of 0.564 T and a maximum energy product of 20 kJ/m(3). As the thickness of the plated film is increased, there is a gradual decrease in the coercivity and anisotropy. The 82-mm-thick film had a perpendicular coercivity of 1150 Oe and a remanence of 0.35 T. While there is a drop in coercivity and anisotropy, the remanence and maximum energy product remain constant for film thicknesses greater than 13 m. There as on for the drop in coercivity and the near constant remanence for thicker CoPtP films is discussed here. The coercivity of the thick Co-rich CoPtP film reported in this work is similar to those reported in the literature; the values of remanence, maximum energy product and saturation magnetization are the highest of all the thick (450 mm) electroplated films in the literature. (C) 2009 Elsevier B.V. All rights reserved.