Projection exposure method, projection exposure apparatus, laser radiation source and bandwidth narrowing module for a laser radiation source

Abstract

In a projection exposure method for the exposure of a radiation-sensitive substrate arranged in the region of an image surface of a projection objective with at least one image of a pattern of a mask arranged in the region of an object surface of the projection objective, laser radiation having a spectral intensity distribution I(ω) dependent on the angular frequency ω is used. The laser radiation is characterized by an aberration parameter α in accordance with: α := ∫ I ⁡ ( ω ) ⁢ ω 2 ⁢ ⅆ ω ∫ I ⁡ ( ω ) ⁢ ⅆ ω and a coherence time τ in accordance with: τ = ∫ I ⁡ ( ω ) 2 ⁢ ⅆ ω [ ∫ I ⁡ ( ω ) ⁢ ⅆ ω ] 2 The laser radiation is introduced into an illumination system for generating an illumination radiation directed onto the mask, and the pattern is imaged onto the substrate with the aid of a projection objective. The spectral intensity distribution is set so that ατ2≦0.3. The influence of temporally varying speckles on image generation can be reduced by comparison with conventional methods, without simultaneously increasing the influence of chromatic aberrations on image generation.

Dependencies are inferred from the claim text.