ELECTROMAGNETIC STUDY OF THE DIFFRACTION OF LIGHT BY A MASK USED IN PHOTOLITHOGRAPHY

A mask used in photolithography is modelized by a periodic collection of perfectly conducting metallic strips, which are supposed to be infinitely thin and lie on the plane surface of a glass medium. A rigorous electromagnetic study of this model is developed for both TE and TM polarizations. It allows computing diffracted efficiencies and drawing the field maps obtained below the mask illuminated by a plane wave. The predictions obtained by this new method developed for this very special grating are compared with those obtained from previously developed grating theories, valid for gratings with finite groove depth.