Abstract
Versatile computer programs capable of simulating near-contact images from arbitrary objects and illumination are reported. Its capability is demonstrated in examples of combinations of different types of object and illumination. It is concluded that polychromatic illumination is always better than monochromatic illumination, and that polychromatic illumination helps when standing waves in photoresist are considered. Negative masks are easier to print than positive ones, as a negative mask in the sense of optical diffraction means smaller dimension for transparent parts of the mask. Some well designed irregularities in the mask pattern improve the image. The effective depth tolerance is between the limits set by the focusing effect and the image spreading effect. Holographic mask relaxes flatness and exposure tolerance. The possibility is pointed out of combining the optical image intensity with the dynamic characteristics of the photoresist and the substrate to evaluate the actual developed image on the photoresist. Results of extensive test programs are enclosed.