Stochastic simulation of photon propagation in Si for extreme-ultraviolet mask-defect inspection

Extreme-ultraviolet (EUV) light is used to inspect the Si photomask by analyzing the reflective photons. We demonstrated the re-emitting EUV photons from the flat Si surface and a two-dimensional semicircular Si defect by using the Monte Carlo method with a Gaussian phase function, respectively. The results of a model based on the Feynman path integral matches those of the Monte Carlo method very well by multiplying a correction function. The intensity of re-emitting photons from the defect can offer enough signals at the angle intersecting the surface less than 20°.