Patent ID: 8152928

Claim:
A method of substrate cleaning with a cleaning tank, an ultrasonic generator and a plurality of supplying members with each supplying member of the plurality being positioned at a different vertical level within the tank, said method comprising the steps of: immersing a semiconductor wafer in a cleaning liquid in the cleaning tank; generating, with the ultrasonic generator, ultrasonic waves in the cleaning liquid while causing the plurality of supplying members to supply cleaning liquid into the tank; and during generating of ultrasonic waves and while the plurality of supplying members are supplying cleaning liquid, changing a cleaning liquid supply rate of at least one supplying member so as to change the amount of cleaning liquid supplied at the level corresponding to said at least one supplying member, changing a cleaning supply rate of at least another supplying member so as to change the amount of cleaning liquid supplied at the level corresponding to said at least another supplying member, and causing different members of the supplying members to simultaneously supply the cleaning liquid at different dissolved gas concentrations.