Maskless exposure method

A maskless exposure method of drawing a circuit pattern on a photosensitive resist film, comprising:

• moving a substrate on which the photosensitive resist film is formed with respect to a projection optical system;
• scanning, by the projection optical system, the substrate in a first direction;
• shifting a scanning region in a second direction that crosses the first direction;
• scanning the substrate in the first direction so that an overlapping part is formed in the second direction;
• wherein:
• a plurality of marks different from the circuit pattern are exposed in a vicinity of the overlapping part on a pair of the scanning regions adjacent to each other with the overlapping part,
• the plurality of marks are a set of marks at least including two marks disposed on one side of the overlapping part and two marks disposed on another side of the overlapping part;
• deviations between the pair of the scanning regions adjacent to each other in the first direction and in the second direction, and an inclination of exposing light of the projection optical system with respect to the first direction are detected by measuring deviations of distances among the plurality of marks;
• calibration data are obtained from a result of the detecting;
• marks are drawn on a center axis along the first direction in a plurality of the scanning regions by the projection optical system;
• coordinates of two points among the marks drawn by the same projection optical system are measured after the photosensitive resist film is developed;
• the deviation between the pair of the scanning regions adjacent to each other in the first direction is derived from a difference between a distance between the two points in the first direction and a distance in an exposure instruction value between the measured two points in the first direction;
• calibration data of a scanning start timing of the projection optical system are generated from the deviation between the pair of the scanning regions adjacent to each other in the first direction obtained in the measuring the coordinates;
• the deviation between the pair of the scanning regions adjacent to each other in the first direction are measured among the plurality of the scanning regions;
• measured values of the measured deviation in the first direction are averaged;
• the deviation between the pair of the scanning regions adjacent to each other in the first direction are derived;
• and
• calibration data of the inclination of the projection optical system with respect to the first direction are generated from a difference between the deviation between the pair of the scanning regions adjacent to each other in the first direction obtained in the measuring among the plurality of the scanning regions and the deviation between the pair of the scanning regions adjacent to each other in the first direction obtained in the measuring the coordinates;
• and
• correcting the scanning start timing of the projection optical system and adjusting the inclination of the projection optical system with respect to the first direction are performed based on each of the calibration data of the scanning start timing of the projection optical system and the calibration data of the inclination of the projection optical system.