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Proceedings Paper

Simulation of x-ray mask defect printability
Author(s): Srinivas B. Bollepalli; Scott Daniel Hector; Juan R. Maldonado; Jeffrey A. Leavey; Franco Cerrina; Mumit Khan
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Paper Abstract

The printability of defects in x-ray masks was simulated in three dimensions using the CXrL toolset software developed at the University of Wisconsin and resist dissolution software developed in a collaboration between University of California at Berkeley and Motorola. Isolated defects on mask membranes and isolated defects on pellicle membranes mounted behind the mask membrane were modeled. Defects close to x-ray absorber features and absorber fabrication defects were also considered. Spheres and parallelepiped defect shapes composed of PMMA, ammonium sulfate, and stainless steel were modeled at exposure gaps in the range 10 - 50 micrometers. Attenuation of a variety of potential defect materials was calculated for the IBM Advanced Lithography Facility Helios synchrotron source and beam-line x-ray spectrum. The dose-to-clear for 400 and 500 nm thickness APEX-E films was then used to predict what thickness of defect material would result in a printed defect. Image formation model predictions of defect printability in APEX-E resist were compared to attenuation calculations, indicating that defect shape and x-ray phase shift in the defect material has a profound impact on defect printability for materials that are not highly attenuating. Spheres printed more readily than parallelepipeds. Increasing the exposure gap reduced printability slightly. Experiments to determine the printability of organic spheres added to x-ray masks were compared to simulation to verify its accuracy. Based on modeling results, the minimum size of isolated defects on x- ray masks that printed are presented. The minimum size of defects that changed printed line-width were also discussed. Based on these results, defect inspection sensitivity, cleaning capability, and repair resolution for less than or equal to 175 nm line-width x-ray masks can be established.

Paper Details

Date Published: 7 July 1997
PDF: 12 pages
Proc. SPIE 3048, Emerging Lithographic Technologies, (7 July 1997); doi: 10.1117/12.275772
Show Author Affiliations
Srinivas B. Bollepalli, Univ. of Wisconsin/Madison (United States)
Scott Daniel Hector, Motorola (United States)
Juan R. Maldonado, IBM Semiconductor Research and Development Ctr. (United States)
Jeffrey A. Leavey, IBM Semiconductor Research and Development Ctr. (United States)
Franco Cerrina, Univ. of Wisconsin/Madison (United States)
Mumit Khan, Univ. of Wisconsin/Madison (United States)

Published in SPIE Proceedings Vol. 3048:
Emerging Lithographic Technologies
David E. Seeger, Editor(s)

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