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Proceedings Paper

The limit to 4X EUVL
Author(s): Kiwamu Takehisa
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Paper Abstract

Considering the usage extension of ArF immersion lithography down to the node of hp 22nm, EUVL should be able to cope with at least the 16 nm and preferably the 11 nm nodes. However, numerical aperture (NA) of projection optics in EUVL exposure tools needs to be around 0.4 which requires the oblique angle of around 8 degrees for the illumination. When one considers that the thickness of multilayer is around 280 nm, the reflectivity drop area at the edge of absorbers has the width of approximately 40 nm that corresponds to the width of 10 nm on wafer. There is another serious problem. Particle check will become extremely difficult for a pellicle-less EUVL mask with smaller feature size. Killer particles cannot be detected by an optical inspection system any longer at 22 nm and smaller. In consideration of all these serious problems, the only simple solution is to increase the mask magnification factor from the conventional 4X to 8X.1-4) Although is has been reported that the throughput of an 8X exposure too is 30-70% compared with that of 4X,5X the throughput can be increased to be equal or even higher than that of 4X when 450 nm wafer is applied.

Paper Details

Date Published: 4 December 2008
PDF: 8 pages
Proc. SPIE 7140, Lithography Asia 2008, 71403C (4 December 2008); doi: 10.1117/12.804260
Show Author Affiliations
Kiwamu Takehisa, Lasertec Corp. (Japan)

Published in SPIE Proceedings Vol. 7140:
Lithography Asia 2008
Alek C. Chen; Burn Lin; Anthony Yen, Editor(s)

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