Abstract

Although the physics of image formation is well known, practical questions in lithography, such as that of the depth of focus and the effects of source shape, cannot be conveniently approached by analytical methods. The interactions between the contributions to the image from the various points of the object are so complicated that computation is usually necessary to determine image irradiances. Numerous digital image simulations have appeared in the literature, but—presumably because of the computation time required—most have been of objects varying in one direction. We have performed a number of 2-D image simulations of lithographic-type objects to investigate effects of the various parameters of imaging, such as numerical aperture, defocus, aberrations, and source size and position.

© 1985 Optical Society of America