| 摘要 |
PROBLEM TO BE SOLVED: To provide a method of producing a mask blank substrate which reduces the in-plane defect removal distribution in a wet etching process for reducing foreign matter defects of a mask blank substrate to improve efficiency of the wet etching process.SOLUTION: In wet-etching a first principal surface 101, or the front surface side, of a mask blank substrate 100 by injecting an etching liquid 201, the temperature of the wet etching liquid is adjusted to be higher than ordinary temperature before injection, and the liquid 202 with the temperature adjusted to be higher than ordinary temperature is supplied to a second principal surface 102, or the back surface side, of the mask blank substrate. Preferably, the temperature difference between the liquid 202 with the temperature adjusted to be higher than ordinary temperature and the etching liquid 201 is adjusted to ±10°C or smaller. |
