| 摘要 |
PURPOSE:To measure aberration amount of a projection optical system with high speed and precision without using SEM, by comparing the respective exposure amounts when resist images corresponding with a first edge and a second edge appear. CONSTITUTION:The pattern of a reticle is exposed on a wafer, and whether an image corresponding with the edge of the pattern exists is observed. That is, exposure times T1, T2 wherein resists at positions corresponding with two edges of a pattern begin to be exposed to light are obtained, and the ratio T2/T1 is made the ratio 11/12 of the maximum values (peaks) of two image intensities. From said ratio, the unsymmetric amount of image intensity is obtained as the unsymmetric aberration amount of a projection optical system by the coma aberration of the projection optical system. Figure shows the intensity ratio of two peaks to unsymmetric aberration amount of the projection optical system caused by the difference of sigma value of an illumination optical system. It is known that the intensity ratio of peaks increases in proportion to the coma aberration, and its change ratio increases when the sigma value is decreased. |
