Coating film forming method, coating film forming apparatus, and storage medium
A method of forming a coating film includes horizontally supporting a substrate, supplying a coating solution to a central portion of the substrate and spreading the coating solution by a centrifugal force by rotating the substrate at a first rotational speed, decreasing a speed of the substrate from the first rotational speed toward a second rotational speed and rotating the substrate at the second rotational speed to make a surface of a liquid film of the coating solution even, supplying a gas to a surface of the substrate when the substrate is rotated at the second rotational speed to reduce fluidity of the coating solution, and drying the surface of the substrate by rotating the substrate at a third rotational speed faster than the second rotational speed.
1. A method of forming a coating film, comprising:
horizontally supporting a substrate in a rotatable substrate support part around a vertical axis;
supplying a coating solution to a central portion of the substrate and spreading the coating solution by a centrifugal force by rotating the substrate at a first rotational speed;
subsequently, decreasing a speed of the substrate from the first rotational speed toward a second rotational speed and rotating the substrate at the second rotational speed to make a surface of a liquid film of the coating solution even;
supplying a gas to a surface of the substrate by a gas nozzle while repeatedly reciprocating the gas nozzle between a first position and a second position, when the substrate is rotated at the second rotational speed to reduce fluidity of the coating solution; and
after that, drying the surface of the substrate by rotating the substrate at a third rotational speed faster than the second rotational speed,
wherein the first position is located at an outer edge of the substrate, and the second position is located at a predetermined distance from a center of the substrate and is closer to the center of the substrate than the first position.
2. The method of claim 1 , wherein the drying the surface of the substrate by rotating the substrate at a third rotational speed comprises setting an annular member formed annularly along a circumferential direction of the substrate at a position to cover an upper side of a peripheral portion of the substrate, and flow-rectifying an air current above the peripheral portion of the substrate by the annular member.
3. The method of claim 1 , wherein the second rotational speed is 1000 rpm or lower.
4. The method of claim 1 , wherein the third rotational speed is 1800 rpm or higher.
5. The method of claim 1 , wherein a position near the center of the substrate closest to a region to which the gas is supplied on the surface of the substrate is a position ranging from 50 mm to 120 mm in a peripheral direction from the center of the substrate.
6. The method of claim 1 , wherein, in the supplying a gas to a surface of the substrate, a heated gas is supplied.