Coating film forming apparatus, coating film forming method, and storage medium

A coating film forming method, comprising:

• horizontally holding a substrate with a substrate holding unit;
• positioning a ring-shaped member at a processing position where an air flow flowing above a peripheral edge portion of the substrate is straightened, the ring-shaped member annularly installed along a circumferential direction of the substrate so as to cover an upper side of the peripheral edge portion of the substrate;
• supplying a coating liquid to a central portion of the substrate;
• in a state in which the ring-shaped member is positioned at the processing position, rotating the substrate held in the substrate holding unit at a first revolution number by a rotating mechanism such that the coating liquid supplied to the central portion of the substrate is diffused toward the peripheral edge portion of the substrate by a centrifugal force;
• bringing the ring-shaped member to a retreated position by moving the ring-shaped member upward from the processing position with respect to the substrate by an elevator mechanism, the retreated position being a position where an air flow flowing near a front surface of the substrate is prevented from becoming turbulent due to a change in the revolution number of the substrate;
• and
• reducing the revolution number of the substrate to a second revolution number lower than the first revolution number, wherein the method further comprising:
• in parallel with supplying the coating liquid to the substrate, rotating the substrate at a coating liquid supply revolution number;
• and then in parallel with stopping the supply of the coating liquid to the substrate, rotating the substrate at a liquid pool formation revolution number, the liquid pool formation revolution number being lower than the coating liquid supply revolution number, wherein rotating the substrate at a first revolution number is performed after rotating the substrate at a liquid pool formation revolution number;
• wherein the method further comprising:
• in parallel with rotating the substrate at a first revolution number, evacuating the inside of a cup, which surrounds the substrate held in the substrate holding unit, at an exhaust flow rate associated with the first revolution number, wherein the first revolution number is changeable in a processing of a next substrate.