Patent ID: 8318288
Filing Date: 2012-11-27
Classification: G02B,G03F,Y10T

Abstract:
1. An optical element, comprising: a layer of material at least partially transmissive for EUV radiation with a wavelength λ in the range of 5-20 nm, the layer of material including a material selected from the group consisting of Be, B, C, Si, P, S, K, Ca, Sc, Br, Rb, Sr, Y, Zr, Nb, Mo, Ru, Rh, Ag, Ba, La, Ce, Pr, Pa, U, and combinations thereof; and a top layer of material including a structure having an rms roughness value, wherein transmission through the top layer is at least 30% for EUV radiation with the wavelength λ in the range of 5-20 nm, and the rms roughness value is equal to or larger than λ/10 for spatial periods equal to or smaller than λ/2, the top layer of material including a material selected from the group consisting of Be, B, C, Si, P, S, K, Ca, Sc, Br, Rb, Sr, Y, Zr, Nb, Mo, Ru, Rh, Ag, Ba, La, Ce, Pr, Ir, Au, Pa, U, and combinations thereof.