Effects of process parameters on low frequency modulation on sputtered disks for longitudinal recording

Abstract

In-line magnetron sputtering systems with nonrotational substrate fixturing are attractive as a way to produce magnetic media (e.g., hard disks) in large quantities. However, magnetic materials sputtered in in-line sputtering systems seem to have an inherent magnetic anisotropy correlated to the direction of substrate travel, resulting in a low frequency modulation of the readback signal when typical magnetron sputtering parameters (e.g., Ar pressure, sputtering rate) are used. Experiments have been carried out to determine the effects of such parameters as argon pressure, static sputtering rate, magnetic field, film thickness, substrate temperature, and others on this low frequency modulation. Results of experiments performed on magnetic films consisting of 80% Co–20% Ni alloy over a Cr underlayer indicate that low frequency modulation can be suppressed to an acceptably low level mainly through the proper optimization of pressure and rate.