Role of substrate bias on the magnetic properties and microstructure of CoCrPt:SiO2 perpendicular recording media

Abstract

The role of substrate bias during the sputter deposition of various layers of double-layered CoCrPt−SiO2 perpendicular recording media has been investigated in order to understand the physical mechanisms behind the various effects observed. Perpendicular recording media with dual Ru intermediate layers were investigated using several magnetic and microstructural characterization techniques. It was observed that, in general, the application of a bias voltage during the deposition of the seedlayer (Ta) and the first intermediate layer (Ru) is helpful in reducing the c-axis dispersion of the recording layer. For the other layers, application of bias voltage leads to deterioration in the magnetic properties. It was also observed that the application of a bias voltage during the deposition of the first intermediate layer (especially Ru) may not enhance the preferred growth of Ru hexagonal-close-packed (00.2) planes parallel to the disk surface, as predicted before. However, the bias voltage on the Ru layer still reduces the c-axis dispersion of the magnetic layer. From the omega-offset x-ray diffraction investigations, it is estimated that the lattice parameter “a” of the Ru layer is reduced slightly with bias voltage, which could probably lead to a reduction in the lattice mismatch between the Ru layer and Co-alloy layer. Bias conditions also could lead to improved interface condition. Such an improvement in the lattice matching or interface conditions could probably be the cause of the reduction of c-axis dispersion of the recording layer.