| 摘要 |
PROBLEM TO BE SOLVED: To provide a method and an apparatus for chemically strengthening a glass substrate for an information recording medium by which the strength of the glass substrate after chemical strengthening is secured, the flatness of the glass substrate is maintained and chemical strengthening is efficiently carried out. SOLUTION: A plurality of glass substrates 23 are immersed in a heated and melted chemical reinforcing treatment liquid 14 within a chemical strengthening tank in the state where they are supported by the supporting member 22 of a holder. Thereby, the ion exchange of a lithium ion and a sodium ion which exist in the vicinity of the surface of the glass substrate 23, and the potassium ion having larger ionic radius than that of the lithium ion and sodium ion in the processing liquid 14, and chemical strengthening is carried out. The amount of the processing liquid 14 existing between the glass substrates 23 is set to be 1.4 to 71 g/cm<2> with respect to the surface area of the glass substrate 23. The space between the glass substrates 23 is desirably 0.3 to 1.3 cm.
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