Abstract: An etching control method includes (a) collecting shape data including height information of a ring assembly measured at a plurality of locations on a surface of the ring assembly, the ring assembly being disposed to surround an area on a stage on which a substrate is placed; (b) specifying a control amount from the shape data collected in (a) by using a relationship model representing a relationship between pre-collected shape data that has been collected in advance and a control amount capable of controlling a sheath distribution near the ring assembly by which a tilting angle of a recess formed in the substrate by plasma etching is within an allowable range; and (c) applying the control amount specified in (b) thereby controlling the sheath distribution near the ring assembly.

Abstract: A magnetic recording medium includes: a nonmagnetic support having both principal planes, a nonmagnetic layer formed on one principal plane of the nonmagnetic support and containing a nonmagnetic powder, a conductive particle and a binder, and a magnetic layer formed on the nonmagnetic layer and containing a magnetic powder, a conductive particle and a binder, wherein each of the nonmagnetic layer and the magnetic layer is prepared in a wet on dry mode, and a conduction point particle size of the conductive particle contained in the magnetic layer falls within the range of 3 times or more and not more than 5 times an average thickness of the magnetic layer.