Polishing composition and polishing method of substrate for memory and hard disk

Abstract

A polishing composition for a substrate to be used for a memory hard disk, which comprises the following components (a) to (d):(a) water,(b) at least one compound selected from the group consisting of a polyoxyethylene polyoxypropylene alkyl ether and a polyoxyethylene polyoxypropylene copolymer,(c) at least one compound selected from the group consisting of nitric acid, nitrous acid, sulfuric acid, hydrochloric acid, molybdic acid, sulfamic acid, glycine, glyceric acid, mandelic acid, malonic acid, ascorbic acid, glutamic acid, glyoxylic acid, malic acid, glycolic acid, lactic acid, gluconic acid, succinic acid, tartaric acid, maleic acid and citric acid, and their salts, and(d) at least one abrasive selected from the group consisting of aluminum oxide, silicon dioxide, cerium oxide, zirconium oxide, titanium oxide, silicon nitride and silicon carbide.

Description

Background of the invention [0001] The present invention relates to a polishing composition for polishing the surface of a magnetic disk substrate for a memory hard disk (ie, a memory component used in, for example, a computer), and a polishing method using the composition. [0002] Specifically, the present invention relates to a polishing composition and a polishing method using the composition. Compared with substrates polished using conventional polishing compositions, when polishing substrates for storage hard disks represented by Ni-P magnetic disks, Ni-Fe magnetic disks, aluminum magnetic disks, boron carbide magnetic disks, and carbon magnetic disks, the peripheral portion (hereinafter referred to as edge portion) does not increase the vertical chipping degree of the edge, and a magnetic disk device having a high capacity and a high recording density can be manufactured. Background of the invention [0003] There has been an ongoing effort to make a memory hard disk...

AI Technical Summary

Problems solved by technology

[0012] However, in the case of polishing a substrate with the above-mentioned conventional polishing composition, the edge of the substrate is polished more than the plane of the substrate during polishing, thus causing vertical defects in the peripheral portion of the substrate.

It is impossible to store data on the edge part of the substrate with vertical defects, so that the data storage area is reduced

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