Patent ID: 8284520
Filing Date: 2012-10-09
Classification: G11B

Abstract:
1. A method for producing a magnetic recording medium comprising a magnetic layer having a magnetic recording pattern comprising elevations constituting magnetic recording regions and depressions constituting boundary regions for partitioning the magnetic recording regions, and a continuous protective carbon overcoat on the magnetic layer, wherein the method comprises the following steps (a) through (f) which are carried out in this order: (a) forming a continuous magnetic layer on a surface of a non-magnetic substrate; (b) forming a mask layer for forming a magnetic recording pattern on the magnetic layer; (c) subjecting the mask layer to patterning; (d) subjecting, to ion-milling, regions to be formed into boundary regions for partitioning magnetic recording regions in the magnetic layer, while the mask layer remains on the regions to be formed into the magnetic recording regions, whereby elevations constituting the magnetic recording regions and depressions constituting the boundary regions are formed in the magnetic layer; (e) removing the mask layer; and then, (f) forming by a CVD method a continuous protective carbon overcoat on the magnetic layer, in a manner such that portions of the carbon overcoat located on the magnetic recording regions-constituting elevations of magnetic layer are thicker than portions of the carbon overcoat located on the boundary regions-constituting depressions of magnetic layer; and wherein the method further comprises a procedure selected from the following procedures [1], [2] and[3]: [1] a procedure of forming the protective carbon overcoat by a CVD method while a bias voltage is imposed to the substrate in the protective carbon overcoat-forming step (f), [2] a procedure of conducting ion-implantation in the magnetic recording regions and the boundary regions in the magnetic layer after the mask layer-removing step (e) but prior to the formation of the protective carbon overcoat in the step (f), and [3] a procedure of conducting ion-implantation in the magnetic recording regions in magnetic layer while the mask remains on the boundary regions in magnetic layer after the mask layer-removing step (e) but prior to the formation of the protective carbon overcoat in the step (f), whereby the magnetic recording regions are roughened.