EUV mask defects and their removal

Abbas Rastegar; Vibhu Jindal

doi:10.1117/12.923882

16 April 2012 EUV mask defects and their removal

Abbas Rastegar, Vibhu Jindal

Proceedings Volume 8352, 28th European Mask and Lithography Conference; 83520W (2012) https://doi.org/10.1117/12.923882
Event: 28th European Mask and Lithography Conference (EMLC 2012), 2012, Dresden, Germany

Abstract

EUV mask defectivity is one of the challenges of realizing EUV lithography. EUV mask defects are a combination of substrate, multilayer blank, and absorber patterning defects. Each defect on the substrate or blank may be able to print depending on different factors. Therefore, at every stage of EUV mask manufacturing, care must be taken to control defectivity. This paper reviews EUV mask defectivity during manufacturing and use. Principles involved in EUV defect detection and sizing are discussed. With EUV, examining defects in a two dimensional (2D) space where defect detection can be correlated with defect printability predictions is most useful. To determine the critical defect size on a multilayer, existing printability prediction modeling can be used. However to calculate defect size on a substrate, detailed information about the multilayer deposition process is needed. Defects < 2 nm deep with a full width half maximum (FWHM) < 20 nm on the substrate will be completely smoothed by the current multilayer deposition processes in use at SEMATECH. Defects > 2 nm deep with a FWHM < 20 nm after multilayer deposition become wider but their depth remains constant (0.6 nm) regardless of their width on the substrate. Cleaning-induced pits will contribute to both low thermal expansion material (LTEM) and Ru-capped multilayer blank defectivity. Particles added by the cleaning tool and processes are another key contributor to EUV mask, blank and substrate defectivity. Changes in EUV reflectivity due to multiple cleanings are likewise critical. Cleaning chemistries will also etch the absorber lines and antireflecting coatings (ARCs), which in turn will alter the mask critical dimensions (CDs). Finally, cleaning the mask may increase its surface roughness, which may change the line edge roughness (LER).

Citation Download Citation

Abbas Rastegar and Vibhu Jindal "EUV mask defects and their removal", Proc. SPIE 8352, 28th European Mask and Lithography Conference, 83520W (16 April 2012); https://doi.org/10.1117/12.923882

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