MODELING OF IMAGES OF SQUARE-WAVE GRATINGS AND ISOLATED EDGES USING RIGOROUS DIFFRACTION THEORY

The angular spectrum approach, using a rigorous electromagnetic calcul ation for the scatter function of a grating, is used to calculate imag es of dielectric surface-relief square-wave gratings. Coherent bright field, dark field, and confocal images are calculated and presented, t he rigorous Modal Method being used to calculate the scatter function of the specimen. The superior metrological information available from a confocal imaging system over the others is clearly demonstrated, as is the sectioning characteristic of the system. The periods of the gra tings have been chosen so that the images approximate to those from is olated edges.