PROJECTION EXPOSURE TOOL FOR MICROLITHOGRAPHY AND METHOD FOR MICROLITHOGRAPHIC EXPOSURE

摘要

A projection exposure tool (210) for microlithography configured for exposing a substrate (20) to be structured by respective imaging of mask structures of a reticle (214) comprising at least one layer onto different regions of the substrate (20) in a number of exposure steps, comprising: irradiation optics (213) configured to irradiate a front side (216) of the reticle with exposure radiation (226) during teh exposure of the substrate (20), a measuring apparatus (240) for taking a topography measurement on the reticle layer, which measuring apparatus (240) is arranged to irradiate measuring light onto a rear side (215) of teh reticel (214), and a control apparatus (60) which is configured to control the measuring apparatus (40) such that during the period of time required to expose the substrate the topography of at least one section of the reticle layer is measured.