<title>Simulations on step-and-scan optical lithography</title>

Step and scan projection printers overcome the most stringent restriction of step and repeat cameras: the trade off between the resolving power of the lithographic lens and its image field. In a scanning projection printer the reticle and wafer both have to be moved with a constant velocity, keeping their speed ratio equal to the reduction of the lens. The length of the circuit is now reticle limited. An additional extension consists in stitching several lanes together in order to lengthen the dimension perpendicular to the scan direction. However, lens aberrations, mechanical vibrations as well as synchronization errors of the stages, deteriorate the image transfer. The aim of this article is the classification and treatment of these scan- induced deteriorations. So-called contrast transfer curves are calculated offering the possibility of gaining quantitative values of the disturbance amplitudes for permissible contrast drops. Additionally, exposure-defocus (ED) trees are constructed as an evaluation criterion of the scan-induced image degradation.