| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing substrates for mask blanks surely preventing remaining of abrasive grains on a substrate surface after polishing and washing, and stably providing a highly smooth substrate surface.SOLUTION: The method for producing substrates for mask blanks includes: a polishing step of bringing a polishing pad into contact with a surface of a glass substrate, supplying the surface of the glass substrate with polishing liquid including abrasive grains, relatively moving the glass substrate and the polishing pad, and polishing the surface of the glass substrate; and a washing step of washing the surface of the glass substrate. The abrasive grain is a cationic colloidal silica. The pH of the polishing liquid in the polishing step is within a range of 1-5, and a zeta potential in a range of pH 1-5 is not less than 30 mV and not more than 60 mV. Both of the polarity of the zeta potential of the polishing liquid used in the polishing step and the polarity of the zeta potential of washing liquid when washing the surface of the glass substrate in the washing step match to be positive. |
