Shin-etsu Handotai Co., Ltd.

Shin-etsu Chemical Co., Ltd.

Itsuo Kuroyanagi

Hideo Kaneko

Yasuaki Nakazato

Hisayoshi Yamaguchi

Yukio Nakazima

Toyofumi Aoki

A template-type wafer polishing method in which a plurality of wafers are polished while they are fitted in the corresponding number of circumferentially spaced engagement holes in a template blank, with the backsides of the respective wafers held by a backing pad, wherein the backing pad has, in its one surface next to the template blank, a plurality of annular grooves each extending along a corresponding one of the engagement grooves in the template blank for relieving a stress concentrated on the peripheral edge of each wafer. The polished wafer is free from deformation, such as declination caused at the peripheral edge thereof due to stress concentration and, hence, has an extremely high degree of flatness. The backing pad and a method of making the same are also disclosed.

Method of polishing wafers, a backing pad used therein, and method of

Proposed is a substrate of a magnetic recording medium in the form of an annular disk made from a single crystal of silicon which is imparted with greatly improved mechanical strengths to withstand mechanical shocks and high-velocity revolution. Different from conventional annular disks as formed by a mechanical working to form the outer contour and the circular center opening, the peripheral surfaces of the inventive annular disk are freed from the work-stressed surface layer by a chemical etching treatment undertaken after the mechanical working.

Substrate for magnetic recording medium

Method for detecting crystal defects in semiconductor silicon which comprises treating a preliminarily mirror etched crystal of semiconductor silicon with a detecting solution which is a mixture of about 50% hydrofluoric acid solution and concentrated nitric acid in a ratio of 1000 to 0.1-20 by volume added with an anionic surfactant, and thereafter applying renewedly a mirror etching thereto. Also provided is a detecting solution therefor. Practice of the method causes no occupational disease and no environmental pollution with respect to hexavalent chromium.

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Chiba-ken, Japan

Itsuo Kuroyanagi