Patent ID: 9001304
Filing Date: 2015-04-07
Classification: G03F

Abstract:
1. A projection exposure system for microlithography, comprising: a mask holding device holding a mask with mask structures disposed on the mask, a substrate holding device holding a substrate, projection optics arranged to image the mask structures onto the substrate during an exposure process, a reference element, a measurement structure which is disposed in a defined position with respect to the reference element, which defined position is mechanically uncoupled from the mask holding device, a detector arranged to record an image of the measurement structure imaged by the projection optics, wherein the mask holding device, the substrate holding device, the projection optics, the measurement structure, and the detector are arranged and configured such that the projection optics image the mask structures onto the substrate via a first optical path that terminates on the substrate and image the measurement structure to the detector at the same time via a second optical path that differs from the first optical path and terminates on the detector, an evaluation device configured to establish a lateral position of the image of the measurement structure in an area of the detector during the exposure process, and a distance sensor configured to obtain a respective defined position of at least one of the measurement structure and the detector by measuring a respective distance from the reference element to at least one of the measurement structure and the detector.