EUV reticle inspection using phase retrieval algorithms: a performance comparison

RESCAN is an actinic patterned EUV mask metrology tool based on coherent diffraction imaging. An image of the reticle is reconstructed from recorded diffraction patterns using a phase retrieval algorithm. As semiconductor manufacturing has moved to EUV lithography to meet the next technology node, accurate photomask metrology with resolution in the nanometer range is crucial for high production yield. To find the optimal reconstruction strategy to achieve the highest resolution, sensitivity and reconstruction speed in RESCAN, we compared three algorithms. We demonstrate that, for the current setup, the best approach is the difference map algorithm.

[1]  Y. Ekinci,et al.  Coherent diffractive imaging methods for semiconductor manufacturing , 2017 .

[2]  W. Brocklesby,et al.  Ptychographic coherent diffractive imaging with orthogonal probe relaxation. , 2016, Optics express.

[3]  Iacopo Mochi,et al.  Actinic inspection of EUV reticles with arbitrary pattern design , 2017, Photomask Technology.

[4]  Andreas Menzel,et al.  Reconstructing state mixtures from diffraction measurements , 2013, Nature.

[5]  K. Nugent,et al.  Diffractive imaging using partially coherent x rays. , 2009, Physical review letters.

[6]  Iacopo Mochi,et al.  Absorber and phase defect inspection on EUV reticles using RESCAN , 2019, Advanced Lithography.

[7]  Keith A. Nugent,et al.  Coherent lensless X-ray imaging , 2010 .

[8]  AZ,et al.  Beam drift and partial probe coherence effects in EUV reflective-mode coherent diffractive imaging , 2018 .

[9]  Iacopo Mochi,et al.  RESCAN: an actinic lensless microscope for defect inspection of EUV reticles , 2017 .

[10]  J. Goodman.  Introduction to Fourier optics , 1969 .

[11]  Andreas Menzel,et al.  Probe retrieval in ptychographic coherent diffractive imaging. , 2009, Ultramicroscopy.

[12]  J. Rodenburg,et al.  An improved ptychographical phase retrieval algorithm for diffractive imaging. , 2009, Ultramicroscopy.

[13]  J. Rodenburg.  Ptychography and Related Diffractive Imaging Methods , 2008 .

[14]  Manuel Guizar-Sicairos,et al.  Iterative least-squares solver for generalized maximum-likelihood ptychography. , 2018, Optics express.