Effects of RF bias on the texture, magnetics, and recording properties of RF sputtered CoCr/Cr longitudinal thin film media

The effects of RF bias on the texture, magnetics, and recording properties of CoCr/Cr films deposited on glass and NiP/AlMg disks by RF sputtering are examined. It is shown that RF bias improves the crystalline orientations and reduces the grain size of Cr and enhances grain segregations in CoCr/Cr films. It is also found that the preferred orientation of Cr films deposited on NiP/AlMg disks is much better than that of Cr films deposited on glass, although there are no tendencies observed to indicate that one kind of film has a higher coercivity than the other. This result implies that the coercivity of CoCr films is not dominated by the crystalline orientation of Cr underlayers. It is shown that the magnetic properties of CoCr can be improved effectively by RF biasing the substrates. The medium recording performance can be improved by applying a -50-V RF bias to achieve a 3.6-dBV_rms/root(Hz) reduction in medium noise and a 6-dB increase in S/N at 1600 b/mm. This improvement in the noise and signal-to-noise ratio of CoCr/Cr films appears to be related to the decoupling of magnetic interaction between grains