Method and apparatus for analyzing and for removing a defect of an euv photomask

Abstract

The invention refers to a method for analyzing a defect of an optical element for the extreme ultra-violet wavelength range comprising at least one substrate and at least one multi-layer structure, the method comprising the steps: (a) determining first data by exposing the defect to ultra-violet radiation, (b) determining second data by scanning the defect with a scanning probe microscope, (c) determining third data by scanning the defect with a scanning particle microscope, and (d) combining the first, the second and the third data.

1 .- 26 . (canceled) 
     
     
         27 . A method for analyzing a defect of an optical element comprising a substrate and a multi-layer structure, the method comprising:
 determining first data of the defect of the optical element for an EUV wavelength range by exposing the defect of the optical element to ultra-violet radiation;   determining second data of the defect of the optical element for the EUV wavelength range by scanning the defect of the optical element with a scanning probe microscope;   determining third data of the defect of the optical element for the EUV wavelength range by scanning the defect of the optical element with a scanning particle microscope; and   linking the first and second data to the third data.   
     
     
         28 . The method of  claim 27 , wherein linking the first and second data to the third data comprises mutually aligning the first, second and third data relative to each other. 
     
     
         29 . The method of  claim 27 , wherein linking the first and second data to the third data comprises superimposing a pixel of the first data, a pixel of the second data and a pixel of the third data. 
     
     
         30 . The method of  claim 29 , wherein linking the first and second data to the third data comprises transforming at least one member selected from the group consisting of the first data, the second data and the third data so that each pixel of the first data is associated with a pixel of the second data and a pixel of the third data. 
     
     
         31 . The method of  claim 27 , wherein linking the first and second data to the third data comprises compensating deviations with respect to at least one member selected from the group consisting of a scale of the first data, a scale of the second data and a scale of the third data. 
     
     
         32 . The method of  claim 27 , further comprising generating a mark by:
 locally depositing material on at least one element selected from the group consisting of the multi-layer structure and an absorber structure of the optical element; and/or   etching a local depression into am absorber structure of the optical element.   
     
     
         33 . The method of  claim 32 , further comprising using the scanning particle microscope to generate the mark. 
     
     
         34 . The method of  claim 32 , further comprising using the scanning particle microscope to remove the mark. 
     
     
         35 . The method of  claim 32 , wherein linking the first and second data to the third data comprises compensating deviations with respect to at least one member selected from the group consisting of the mark, a scale of the first data, a scale of the second data, and a scale of the third data. 
     
     
         36 . The method of  claim 27 , further comprising recording an aerial image of the defect and/or exposing a wafer. 
     
     
         37 . The method of  claim 36 , wherein recording the aerial image of the defect comprises recording an aerial image in focus and/or recording an aerial image stack by changing the a relative to the optical element for the extreme ultra-violet wavelength range. 
     
     
         38 . The method of  claim 27 , wherein:
 the scanning probe microscope comprises at least one member selected from the group consisting of a scanning force microscope, a scanning tunneling microscope, a magnetic field force microscope, an optical near-field microscope, and an acoustic scanning near-filed microscope; and   the scanning particle microscope comprises at least one member selected from the group consisting of a scanning electron microscope, a focused ion-beam microscope, and an interferometer.   
     
     
         39 . The method of  claim 27 , wherein the defect comprises a buried defect arranged in the multi-layer structure of the optical element, and/or the defect comprises a buried defect arranged in the substrate of the optical element. 
     
     
         40 . The method of  claim 27 , further comprising adapting parameters of a model for the defect of the optical element for the EUV wavelength range to the linked first, second and third data. 
     
     
         41 . The method of  claim 40 , wherein the model for the defect comprises a rotationally symmetrical Gaussian profile which is parameterized by a height and a half-width. 
     
     
         42 . The method of  claim 40 , wherein the model for the defect comprises at least two parameters with respect to a position of the defect of the optical element relative to the at least one mark. 
     
     
         43 . An apparatus configured to analyze a defect of an optical element, the apparatus comprising:
 an ultra-violet radiation source configured to determine first data of the defect of the optical element for an EUV wavelength range;   a scanning probe microscope configured to determine second data of the defect of the optical element for the EUV wavelength range;   a scanning particle microscope configured to determine third data of the defect of the optical element for the EUV wavelength range; and   a linking unit adapted to link the first and second data to the third data.   
     
     
         44 . The apparatus according to  claim 43 , wherein:
 the scanning probe microscope comprises at least one member selected from the group consisting of a scanning force microscope, a scanning tunneling microscope, a magnetic field force microscope, an optical near-field microscope, and an acoustic scanning near-field microscope; and   the scanning particle microscope comprises at least one member selected from the group consisting of a scanning electron microscope, a focused ion-beam microscope and an interferometer.   
     
     
         45 . The apparatus according to  claim 43 , wherein the optical element comprises a photolithographic mask. 
     
     
         46 . The apparatus according to  claim 43 , further comprising a calculation unit configured to adapt parameters of a model for the defect to the first and second data linked to the third data, wherein the model is parameterized by a height or a depth and a half-width.