Phase measurements of EUV mask defects

Rene A. Claus; Yow-Gwo Wang; Antoine J. Wojdyla; Markus P. Benk; Kenneth A. Goldberg; Andrew R. Neureuther; Patrick P. Naulleau; Laura Waller

doi:10.1117/12.2087195

16 March 2015 Phase measurements of EUV mask defects

Rene A. Claus, Yow-Gwo Wang, Antoine J. Wojdyla, Markus P. Benk, Kenneth A. Goldberg, Andrew R. Neureuther, Patrick P. Naulleau, Laura Waller

Author Affiliations +

Proceedings Volume 9422, Extreme Ultraviolet (EUV) Lithography VI; 942217 (2015) https://doi.org/10.1117/12.2087195
Event: SPIE Advanced Lithography, 2015, San Jose, California, United States

Abstract

Extreme Ultraviolet (EUV) Lithography mask defects were examined on the actinic mask imaging system, SHARP, at Lawrence Berkeley National Laboratory. A quantitative phase retrieval algorithm based on the Weak Object Transfer Function was applied to the measured through-focus aerial images to examine the amplitude and phase of the defects. The accuracy of the algorithm was demonstrated by comparing the results of measurements using a phase contrast zone plate and a standard zone plate. Using partially coherent illumination to measure frequencies that would otherwise fall outside the numerical aperture (NA), it was shown that some defects are smaller than the conventional resolution of the microscope. Programmed defects of various sizes were measured and shown to have both an amplitude and a phase component that the algorithm is able to recover.

Citation Download Citation

Rene A. Claus, Yow-Gwo Wang, Antoine J. Wojdyla, Markus P. Benk, Kenneth A. Goldberg, Andrew R. Neureuther, Patrick P. Naulleau, and Laura Waller "Phase measurements of EUV mask defects", Proc. SPIE 9422, Extreme Ultraviolet (EUV) Lithography VI, 942217 (16 March 2015); https://doi.org/10.1117/12.2087195

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