| US 7,371,434 B2 | ||
| Liquid film forming method and solid film forming method | ||
| Shinichi Ito, Yokohama (Japan) | ||
| Assigned to Kabushiki Kaisha Toshiba, Tokyo (Japan) | ||
| Filed on Jul. 25, 2002, as Appl. No. 10/202,657. | ||
| Claims priority of application No. 2001-226471 (JP), filed on Jul. 26, 2001; and application No. 2001-336968 (JP), filed on Nov. 01, 2001. | ||
| Prior Publication US 2003/0072886 A1, Apr. 17, 2003 | ||
| Int. Cl. B05D 1/02 (2006.01) | ||
| U.S. Cl. 427—425 [427/240; 118/321] | 15 Claims |

| 1. 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 g0 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 dR0 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 g0;
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.
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