Patent ID: 8968526
Filing Date: 2015-03-03
Classification: C23C,G11B,Y02T

Abstract:
1. A method for manufacturing a magnetic recording medium, the method comprising: a step for forming at least an orientation control layer on a nonmagnetic substrate which controls the orientation properties of a layer immediately above; and a step for forming a perpendicular magnetic layer by a sputtering process in which the axis of easy magnetization is mainly oriented perpendicularly with respect to the nonmagnetic substrate, wherein in the step for forming a perpendicular magnetic layer, at least a portion of the perpendicular magnetic layer is formed as a magnetic layer having Co as a major component and a granular structure which includes an oxide of at least one nonmagnetic metal selected from the group consisting of Cr, Si, Ta, Al, Ti, W and Mg, wherein a target for forming the perpendicular magnetic layer by the sputtering process is prepared so as to include an oxide of Co and a compound of Co and at least one nonmagnetic metal selected from the group consisting of Cr, Si, Ta, Al, Ti, W and Mg, and to make the proportion of oxygen contained in the target within a range from 2.3 to 4 times higher than the proportion of oxygen contained in the perpendicular magnetic layer, and a sputtering gas pressure at the time of forming the perpendicular magnetic layer is set to 1 Pa or less, and wherein in the step for forming a perpendicular magnetic layer, magnetic particles of the perpendicular magnetic layer are formed as a columnar crystal continuous from particles which constitute the orientation control layer, and wherein in the step for forming a perpendicular magnetic layer, a content of oxides contained in the perpendicular magnetic layer is within a range from 3 to 18 mol % with respect to the total molar amount of elements constituting magnetic particles of the perpendicular magnetic layer.