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Proceedings Paper

CD uniformity control using aerial image-based mask inspection
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Paper Abstract

The industry roadmap for IC manufacturing at design rules of 90nm and below foresees low k1-factor optical lithography at 193nm exposure wavelength. The mask error enhancement factor (MEEF) describes the phenomenon in which errors in the mask critical dimensions (CDs) are not transferred to the wafer in direct proportion to the optical reduction value of the lithography system. In the low-k1 area, the MEEF becomes a significant problem, as it consumes a larger than anticipated percentage of the CD tolerance budget. As a result mask CD uniformity requirements have been tightened significantly to find MEEF-related CD defects prior to the first printing at the wafer fab. The challenge for today's mask inspection methodology lays in the way defects are detected. Conventional mask inspection detects defects according to their dimensions on the mask. Finding MEEF-related CD defects is a challenge as these defects are often caused by CD deviations close to metrology resolution. The paper investigates CD uniformity control using aerial image based mask inspection. The fundamental difference to today's inspection methodology is that a defect is detected based on its impact onto the aerial image projected by the given mask. In order to emulate the aerial image, lithography condition like Numerical Aperture and illumination need to be known to the inspection system. As a large portion of the MEEF is based on the lithography exposure system, MEEF defects can be detected.

Paper Details

Date Published: 2 June 2003
PDF: 6 pages
Proc. SPIE 5038, Metrology, Inspection, and Process Control for Microlithography XVII, (2 June 2003); doi: 10.1117/12.482815
Show Author Affiliations
Shirley Hemar, Etec Systems, Inc., An Applied Materials Co. (Israel)
Anja Rosenbusch, Consultant (United States)
Reuven Falah, Etec Systems, Inc., An Applied Materials Co. (Israel)


Published in SPIE Proceedings Vol. 5038:
Metrology, Inspection, and Process Control for Microlithography XVII
Daniel J. Herr, Editor(s)

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