To uniformize the illuminance distribution by eliminating the nonuniformity of illuminance on the plane of projection because the transmittance of light is not uniform in a projection optical system.
The illuminating light from its source 2 is projected into a mask 9 through the illumination optical systems 3, 4, 5, 6, 7 and 8 with the optical characteristics variable, and the light transmitted through the mask 9 is projected on a wafer 11 through a projection optical system 10 with the image forming characteristics changeable. Consequently, even when the transmission distribution is fluctuated due to a change in the image forming characteristic of the projection optical system 10, the optical characteristic of the illumination optical systems 3, 4, 5, 6, 7 and 8 are changed as the image forming characteristic of the system 10 is changed, hence a specified illuminance distribution can be obtained on the image forming surface, and the pattern on the mask 9 can be nicely transferred on the wafer 11.
NAKAGAWA MASAHIRO
UEHARA MAKOTO
SHIBUYA MASATO
| JPS61169815A | 1986-07-31 |