PROJECTION ILLUMINATION METHOD, PROJECTION ILLUMINATION SYSTEM, LASER BEAM SOURCE AND BANDWIDTH NARROWING MODULE FOR A LASER BEAM SOURCE

摘要

With a projection illumination method for illuminating a radiation sensitive substrate arranged in the region of a screen of a projection objective with at least one image of a pattern of a mask in the region of a surface of the projection objective, laser radiation is used with a spectral intensity distribution l(ω) dependant on the circular frequency ω. The laser radiation is characterized by an aberration parameter α according to: (I) and a coherence time τ: according to (II). The laser radiation is introduced into an illumination system for creating an illumination radiation directed to the mask and the pattern is displayed by means of a projection objective on the substrate. The spectral intensity distribution is set in a way, such that for a line shape parameter ατ2 the condition ατ2 ≤ 0.3 applies. Thus the influence of temporally varying speckles on the image creation can be reduced compared to conventional methods, without increasing the influence of chromatic aberrations on the image creation.