Arrangement for use in a projection exposure tool for microlithography having a reflective optical element
An arrangement for use in a projection exposure tool ( 100 ) for microlithography comprises a reflective optical element ( 10; 110 ) and a radiation detector ( 30; 32; 130 ). The reflective optical element ( 10; 110 ) comprises a carrier element ( 12 ) guaranteeing the mechanical strength of the optical element ( 10; 110 ) and a reflective coating ( 18 ) disposed on the carrier element ( 12 ) for reflecting a use radiation ( 20 a ). The carrier element ( 12 ) is made of a material which upon interaction with the use radiation ( 20 a ) emits a secondary radiation ( 24 ) the wavelength of which differs from the wavelength of the use radiation ( 20 a ), and the radiation detector ( 30; 32; 130 ) is configured to detect the secondary radiation ( 24 ).
1. An arrangement for use in a projection exposure tool for microlithography, the arrangement comprising:
a reflective optical element including a carrier for imparting mechanical strength to said optical element;
said reflective optical element further including a reflective coating disposed on said carrier for reflecting use radiation having a first wavelength;
more than 50% by volume of said carrier comprising a material which, upon interaction with said use radiation, emits a secondary radiation having a second wavelength different from said first wavelength; and,
a radiation detector configured to detect said secondary radiation.
2. The arrangement according to claim 1 , further comprising an evaluation device configured to determine the intensity of radiation irradiated onto said reflective optical element from the intensity of the radiation detected by said radiation detector.
3. The arrangement according to claim 1 , wherein the material emitting the secondary radiation comprises a silicate glass and/or a glass ceramic.
4. The arrangement according to claim 1 , wherein the reflective optical element has the reflective coating disposed on a front side of the carrier element and the radiation detector faces towards a rear side of the carrier element.
5. The arrangement according to claim 1 , wherein the radiation detector is configured to detect light in the visible wavelength range.
6. The arrangement according to claim 1 , wherein the reflective optical element comprises the reflective coating which is configured to reflect radiation in the extreme ultraviolet wavelength range.
7. The arrangement according to claim 1 , wherein the radiation detector is attached to the rear side of the carrier element.
8. The arrangement according to claim 1 , wherein
said material is configured to cause an efficiency of the radiation conversion to be temperature dependent.
9. The arrangement according to claim 8 , wherein the temperature gradient of the radiation conversion efficiency is at least 2% /° C.
10. The arrangement according to claim 8 , further comprising an evaluation unit configured to determine a temperature at the optical element from an intensity of the detected secondary radiation.
11. The arrangement according to claim 10 , further comprising an activation source for generating a beam of an activation radiation, which upon interaction with said material is converted into said secondary radiation; said activation source being configured to scan the activation beam over the optical element; and, said evaluation unit being further configured to correlate the detected secondary radiation with the respective scan position of the activation beam, such that the temperature at the optical element is determined spatially resolved.
12. The arrangement according to claim 11 , wherein the activation radiation comprises the use radiation and the secondary radiation differs from the activation radiation in wavelength.