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Proceedings Paper

A simulation study of cleaning induced EUV reflectivity loss mechanisms on mask blanks
Author(s): Mihir Upadhyaya; Gregory Denbeaux; Arun John Kadaksham; Vibhu Jindal; Jenah Harris-Jones; Byunghoon Lee; Frank Goodwin
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Paper Abstract

It is widely recognized in the semiconductor industry that getting to defect-free extreme ultraviolet (EUV) mask blanks is critical in achieving high volume chip manufacturing yield beyond the 22 nm half-pitch node. Total defectivity of an EUV mask blank depends on the defectivity of substrate and finished mask blank. Finished mask blanks are normally subjected to a cleaning process to get rid of the loosely adhered particles on the top. This is normally done in a spin-spray mask cleaning tool using traditional mask cleaning processes. It is important that this cleaning process does not degrade the properties of the multilayer blank or introduce additional particles or pits during the process. However, standard cleaning processes used to clean multilayer blanks result in EUV reflectivity loss, loss of uniformity in reflectivity, increased roughness and adds pits and particles on mask blanks. The standard cleaning process used consists of multiple steps, each of which may cause the oxidation of Ru capping layer as well as other underlying bilayers, etching of the multilayer stack and increased roughness of the bilayers thus leading to a loss in EUV reflectivity. It is a challenging task to experimentally correlate the processing steps to the resulting damage and to quantify the reflectivity loss. Furthermore, due to the high cost of materials we have not been able to do extensive experiments to determine the root cause of problems. In this work, we have combined mask blank cleaning using standard processes, TEM cross section studies and simulations to quantify the impact of the multilayer oxidation, etching and roughness on the EUV reflectivity loss and mask blank degradation.

Paper Details

Date Published: 23 March 2012
PDF: 13 pages
Proc. SPIE 8322, Extreme Ultraviolet (EUV) Lithography III, 832223 (23 March 2012); doi: 10.1117/12.917972
Show Author Affiliations
Mihir Upadhyaya, Univ. at Albany (United States)
Gregory Denbeaux, Univ. at Albany (United States)
Arun John Kadaksham, SEMATECH North (United States)
Vibhu Jindal, SEMATECH North (United States)
Jenah Harris-Jones, SEMATECH North (United States)
Byunghoon Lee, SEMATECH North (United States)
Frank Goodwin, SEMATECH North (United States)

Published in SPIE Proceedings Vol. 8322:
Extreme Ultraviolet (EUV) Lithography III
Patrick P. Naulleau; Obert R. Wood II, Editor(s)

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