This graph shows minimum EUV dose vs. feature size, for 10% variation, corresponding to 3600 absorbed photons per square feature. A fixed absorption thickness keeps photon number fixed (effectively zero attenuation length), while a fixed aspect ratio has thinner absorber (less absorption) for smaller feature size. For the latter case, a 1/e attenuation length of 50 nm is assumed. The required dose goes from inverse square dependence on feature size to almost inverse cube.