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

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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 t F , the substrate temperature T s , and the sputtering Ar pressure P Ar . The Co 76 Cr 24 films with t F of 50 nm were deposited on glass disks at T s of 230 °C and P Ar of 0.03 Pa. These films were composed of highly c-axis oriented hcp crystallites, in which isolated ferromagnetic areas with lower Cr content C Cr were uniformly distributed in the paramagnetic host matrix with higher C Cr . The diameter of grains was 5–20 nm with voidless grain bounderies and the diameter of lower C Cr areas was as small as 3–5 nm. The perpendicular coercivities H c ⊥ 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 H c ⊥ 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