METHOD FOR MANUFACTURING MAGNETIC DISK SUBSTRATE, AND POLISHING PAD USED IN MANUFACTURE OF MAGNETIC DISK SUBSTRATE

摘要

In order to reduce a root-mean-square roughness Rq of minute undulations in wavelength of 50 to 200μm on a principal surface of a glass substrate, this method for manufacturing a magnetic disk substrate includes a polishing process in which the substrate is sandwiched by a pair of polishing pads, a slurry including polishing abrasive grains is supplied between the polishing pads and the substrate, and the polishing pads and the substrate are slid relative to each other, whereby both of the principal surfaces of the substrate are polished. The polishing pads have a foamed resin layer having a plurality of openings in the surface thereof. When information about a three-dimensional shape of the surfaces of the polishing pads is obtained from a captured image of the surfaces of the polishing pads and then an arithmetic mean roughness Ra on the surfaces of the polishing pads is calculated from the information about the three-dimensional shape, Ra is 0.5μm or less.