Method for manufacturing glass substrate

A method for manufacturing a glass substrate of an information recording medium, the method comprising the steps of:

• preparing a glass plate having a surface with a corrugation height of 5 μm or less that is measured by a multifunctional disk interferometer with light having a wavelength of 0.4 to 5.0 mm;
• polishing a surface of the glass plate with a polishing agent containing cerium oxide;
• and
• washing the surface of the glass plate with a washing agent containing acid, a reducing agent, and fluorine ion.

A method for manufacturing a glass substrate, the method comprising the steps of:

• preparing a glass plate;
• polishing a surface of the glass plate with polishing slurry containing cerium oxide particles;
• washing away the polishing slurry from the glass plate;
• preparing a washing agent containing 10 wt % of nitric acid, 1.0 wt % of ascorbic acid, and 10 ppm of hydrogen fluoride;
• washing the glass plate with the washing agent and removing the cerium oxide particles from the surface of the glass plate;
• washing the glass plate with water;
• and
• washing the glass plate with an alkaline aqueous solution.