Projection exposure system for microlithography with a measurement device

Abstract

A projection exposure system ( 10 ) includes: a mask holding device ( 14 ), a substrate holding device ( 36 ), projection optics ( 26 ) imaging the mask structures ( 20 ) onto the substrate ( 30 ) during an exposure process, and a measurement structure ( 48 ) disposed in a defined position with respect to a reference element ( 16 ) of the projection exposure system, which defined position is mechanically uncoupled from the position of the mask holding device. The projection exposure system also includes a detector ( 52 ) arranged to record an image of the measurement structure imaged by the projection optics. During operation of the system, the imaging of the mask structures and of the measurement structure takes place at the same time by the projection optics. An evaluation device ( 54 ) establishes a lateral position of the image of the measurement structure in the area of the detector during the exposure process.

1 - 8 . (canceled) 
     
     
         9 . A projection exposure system for microlithography comprising:
 projection optics arranged to image mask structures onto a substrate during an exposure process, and   a measuring apparatus configured to monitor lateral imaging stability of the projection optics comprising:   a measurement structure, and   a detector arranged to record an image of the measurement structure imaged by the projection optics,   wherein 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 onto the detector at the same time via a second optical path that differs from the first optical path and terminates on the detector such that the measurement structure is imaged by means of the projection optics directly onto the detector.   
     
     
         10 . The projection exposure system as claimed in claim  1 ,
 wherein the projection optics comprises several optical elements and the second optical path is undeviated between a last optical element of the projection optics and the detector, which last optical element is the one of the optical elements struck last by the first optical path before striking the substrate.   
     
     
         11 . The projection exposure system as claimed in claim  1 ,
 wherein the measuring apparatus further comprises 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.   
     
     
         12 . The projection exposure system as claimed in claim  1 ,
 further comprising a mask holding device holding a mask with the mask structures disposed on the mask and comprising a reference element, wherein the measurement structure is disposed in a defined position with respect to the reference element, which defined position is mechanically uncoupled from the mask holding device.   
     
     
         13 . The projection exposure system as claimed in claim  4 ,
 wherein the reference element comprises a detector related reference element, and wherein the detector is disposed in a defined position with respect to the detector related reference element.   
     
     
         14 . The projection exposure system as claimed in claim  3 ,
 further comprising a substrate holding device for holding the substrate, which substrate holding device is mounted movably in relation to the detector related reference element.   
     
     
         15 . The projection exposure system as claimed in claim  4 ,
 wherein at least one of the measurement structure and the detector are fixed rigidly to the reference element.   
     
     
         16 . The projection exposure system according to claim  1 ,
 wherein the projection optics comprises the reference element, the detector is attached to the projection optics in a fixed position, and   further comprising a sensor module configured to measure a distance between the detector and the substrate holding device during the exposure process.   
     
     
         17 . The projection exposure system according to claim  1 ,
 wherein the substrate holding device is mounted movably in relation to the detector.   
     
     
         18 . The projection exposure system according to claim  1 ,
 wherein the detector has a locally resolving two-dimensional sensor and a detector structure disposed in front of the two-dimensional sensor, and wherein the detector is configured to record the image produced on the detector by the projection optics by recording a pattern produced by superimposing the image of the measurement structure with the detector structure.   
     
     
         19 . A method for monitoring the lateral imaging stability of a projection exposure system for microlithography comprising:
 imaging the mask structures onto a substrate in an exposure process using projection optics of the projection exposure system via a first optical path that terminates on the substrate,   imaging a measurement structure onto a detector during the exposure process using the projection optics via a second optical path that differs from the first optical path and terminates on the detector, wherein the measurement structure is imaged by means of the projection optics directly onto the detector, and   recording the image of the measurement structure on the detector and establishing a lateral imaging stability of the projection optics.