Fabrication of low-noise media-a manufacturing perspective

Three major methods have emerged for the reduction of media noise in thin-film disks and are rooted in the segregation of the grains in the film structure. Physical grain segregation is achieved by altering the adatom mobility of the sputtering process, resulting in physically voided grain structures. Compositional segregation is achieved by sputtering high Cr/Co ratio magnetic alloys at elevated temperatures. A separation into two or more magnetic layers (multilayers) results in a decoupled structure with improved noise characteristics. All three methods have advantages and drawbacks in relation to other recording properties, general disk properties, and manufacturability concerns. The optimum disk for a recording system is not necessarily the lowest noise medium, but a disk that compromises improved noise characteristics with improved recording properties, while allowing for an economic and easily manufacturable process