Substrate cleaning apparatus, substrate cleaning method and non-transitory storage medium

A substrate cleaning method of cleaning a substrate using a cleaning liquid and a gas while rotating the substrate, comprising the steps of:

• by using a first nozzle moving unit that holds a cleaning liquid nozzle configured to supply the cleaning liquid to the substrate and a gas nozzle configured to discharge the gas, and a second nozzle moving unit that holds a gas nozzle configured to discharge the gas to the substrate and is different from the first nozzle moving unit,
• horizontally holding the substrate on a substrate holding unit;
• discharging the cleaning liquid from the cleaning liquid nozzle to a central portion of the substrate while rotating the substrate holding unit around a vertical axis;
• then moving the first nozzle moving unit and discharging the gas from the gas nozzle on the first gas nozzle moving unit to the central portion;
• subsequently moving the first nozzle moving unit toward a peripheral edge side of the substrate while discharging the cleaning liquid and discharging the gas from the gas nozzle on the first nozzle moving unit in a state that a discharge position of the cleaning liquid nozzle is located closer to the peripheral edge side of the substrate than is a discharge position of the gas nozzle on the first nozzle moving unit;
• and
• then moving the first nozzle moving unit and the second nozzle moving unit to the peripheral edge side of the substrate while discharging the gas from the gas nozzle on the second nozzle moving unit and the cleaning liquid from the cleaning liquid nozzle,
• wherein where a distance from the discharge position of the cleaning liquid nozzle to the central portion of the substrate is L1, and a distance from the discharge position of the gas nozzle on the second nozzle moving unit to the central portion of the substrate is L2, when the gas is being discharged from the gas nozzle on the second nozzle moving unit, L2<L1 and moving speeds of both of the nozzle moving units are controlled so that a difference between L1 and L2 gradually decreases with movement of the first nozzle moving unit and the second nozzle moving unit to the peripheral edge side of the substrate.