Patent ID: 7371434

Claim:
A method of forming a liquid film comprising: setting a first position at one end of a moving section of a dropping unit for dropping a chemical solution while moving in a radial direction from an inner periphery to an outer periphery on a rotating substrate; determining a chemical solution feed amount g 0 per unit length of a trajectory of the chemical solution dropped on the substrate from the dropping unit to the substrate and a rotational frequency of the substrate when the dropping unit is positioned on the outermost diameter of a chemical solution supply region of the substrate; setting a move pitch so that the move pitch of the dropping unit in a radial direction occurring at every revolution of the substrate decreases in a geometric progression in such a manner that a move pitch dR is calculated as a product of the move pitch dR 0 immediately before being multiplied by a change rate a smaller than 1 when the dropping unit is present at an arbitrary position while lowering a rotational frequency of the substrate gradually; determining a chemical solution feed speed and substrate rotational frequency from the dropping unit at the first position, the move pitch of the dropping unit at the first position, and the chemical solution feed amount g 0 ; calculating a second position where the dropping unit is located a unit time after the dropping unit is located at the first position from the rotational frequency when the substrate is rotated for the unit time from the time of the dropping unit located at the first position, and the move pitch of the dropping unit at the first position; calculating the relation of the radial position of the dropping unit, chemical solution feed speed, and substrate rotational frequency with respect to the time, by setting the second position again as a new first position until the second position reaches the other end of the moving section, and repeating calculation of the chemical solution feed speed and substrate rotational frequency from the dropping unit at the first position, and calculation of the second position where the dropping unit is located in unit time; and forming a liquid film on the substrate by controlling the radial position of the dropping unit, chemical solution feed speed, and substrate rotational frequency on the basis of the calculated relation to form the liquid film of uniform thickness, wherein in a region where the chemical solution feed speed and substrate rotational frequency are out of the control limit, and the film thickness of the liquid film is larger than the desired film thickness, the chemical solution feed speed and substrate rotational frequency are controlled by condition at a radial position rc of the outermost circumference immediately before the film thickness increases, and the chemical solution discharged from the dropping unit is shielded at the shielding ratio C presented by the value of 1 divided by the product of 1/rc and r, at shielding position r of the dropping unit in the radial direction.