Deposition of perpendicular magnetic recording Co–Cr layers with nanosize domains using a plasma enhanced type of sputtering apparatus

Abstract

Co–Cr thin films for perpendicular magnetic recording layers were deposited using a new type of facing targets sputtering apparatus by optimizing the film thickness tF, the substrate temperature Ts, and the sputtering Ar pressure PAr. The Co76Cr24 films with tF of 50 nm were deposited on glass disks at Ts of 230 °C and PAr of 0.03 Pa. These films were composed of highly c-axis oriented hcp crystallites, in which isolated ferromagnetic areas with lower Cr content CCr were uniformly distributed in the paramagnetic host matrix with higher CCr. The diameter of grains was 5–20 nm with voidless grain bounderies and the diameter of lower CCr areas was as small as 3–5 nm. The perpendicular coercivities Hc⊥ in initial growth regions, the whole film and surface regions were 1100, 1900, and 2700 Oe, respectively. Transmission electron microscope images of these specimens showed that ferromagnetic areas of highly c-axis oriented hcp crystallites with large uniaxial magnetic anisotropy constant are particulate-like. Consequently, the deposition of Co–Cr thin films with much higher Hc⊥ from the initial growth region to that of a surface may be the key technology for preparing perpendicular magnetic recording layers at ultrahigh density above 20 Gbit/in.2