Experimental investigation of a high-k reticle absorber system for EUV lithography

EUV lithography is entering High Volume Manufacturing at relative high Rayleigh factor k₁ above 0.4. In comparison immersion lithography has been pushed to k₁ values of 0.3 or below over the last two decades. One of the strong contributors determining the effective usable resolution is the mask absorber stack. The mask stack alters the diffraction by modifying the phase and intensity of the diffracted orders. In this paper we show the exposure results of a test mask having higher absorbance of EUV light and the advantages of reduced Mask 3D effects to imaging.