| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To efficiently remove particles on the surface of a photomask substrate by ultrasonic cleaning, while preventing particles produced by corrosion of a surface of a cleaning tank or a cleaning carrier from depositing on the photomask substrate. <P>SOLUTION: A method of cleaning the photomask substrate includes: immersing a photomask substrate in a filtered and circulated cleaning liquid; and controlling the power density of ultrasonic waves to an initial value equal to or larger than a threshold at which cavitation is generated, and then gradually and/or continuously reducing the power density of the ultrasonic waves from the initial value until the ultrasonic cleaning in the cleaning tank is finished, so as to prevent particles from generating from surfaces of a cleaning tank or a cleaning carrier. <P>COPYRIGHT: (C)2011,JPO&INPIT</p> |
