| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a manufacturing method of a magnetic disk substrate capable of reducing plunge of alumina into the substrate after coarse polishing.SOLUTION: The manufacturing method of a magnetic disk substrate includes (1) a step of polishing a polishing object surface of a substrate to be polished by using a polishing liquid composition A containing alumina particles, silica particles, and water; (2) a step of rinsing the substrate obtained in the step 1; (3) a step of polishing a polishing object surface of the substrate, obtained in the step 2, by using a polishing liquid composition B containing silica particles and water; (4) a step of cleaning the substrate obtained in the step 3; and (5) a step of polishing the polishing object surface of the substrate, obtained in the step 4, by using a polishing liquid composition C containing silica particles and water. The steps 1 to 3 are implemented by using the same polishing machine, and the step 5 is performed by using a polishing machine different from the polishing machine used in the steps 1 to 3. The gross mass of silica particles used in the steps 1 to 3 is 65.0 mass% or more and 90.0 mass% or less of a sum of gross masses of the alumina particles and the silica particles used in the steps 1 to 3.</p> |
