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Proceedings Paper

Out-of-band exposure characterization with the SEMATECH Berkeley 0.3-NA microfield exposure tool
Author(s): Simi A. George; Patrick P. Naulleau; Senajith Rekawa; Eric Gullikson; Charles Drew Kemp
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Paper Abstract

For the commercialization of extreme ultraviolet lithography (EUVL), discharge or laser produced, pulsed plasma light sources are being considered. These sources are known to emit into a broad range of wavelengths that are collectively referred to as the out-of-band (OOB) radiation by lithographers. Multilayer EUV optics reflect OOB radiation emitted by the EUV sources onto the wafer plane resulting in unwanted background exposure of the resist (flare) and reduced image contrast. The reflectivity of multilayer optics at the target wavelength of 13.5 nm is comparable to that of their reflectivity in the deep ultraviolet (DUV) and UV regions from 100-350 nm. The aromatic molecular backbones of many of the resists used for EUV are equally absorptive at specific DUV wavelengths as well. In order to study the effect of these wavelengths on imaging performance in a real system, we are in the process of integrating a DUV source into the SEMATECH Berkeley 0.3-NA Microfield Exposure Tool (MET). The MET plays an active role in advanced research in resist and mask development for EUVL and as such, we will utilize this system to systematically evaluate the imaging impact of DUV wavelengths in a EUV system. In this paper, we present the optical design for the new DUV component and the simulation-based imaging results predicting the potential impact of OOB based on known resist, mask, and multilayer conditions. It should be noted that because the projection optics work equally well as imaging optics at DUV wavelengths, the OOB radiation cannot be treated simply as uniform background or DC flare.

Paper Details

Date Published: 17 March 2009
PDF: 12 pages
Proc. SPIE 7271, Alternative Lithographic Technologies, 72710X (17 March 2009); doi: 10.1117/12.814429
Show Author Affiliations
Simi A. George, Lawrence Berkeley National Lab. (United States)
Patrick P. Naulleau, Lawrence Berkeley National Lab. (United States)
Senajith Rekawa, Lawrence Berkeley National Lab. (United States)
Eric Gullikson, Lawrence Berkeley National Lab. (United States)
Charles Drew Kemp, Lawrence Berkeley National Lab. (United States)

Published in SPIE Proceedings Vol. 7271:
Alternative Lithographic Technologies
Frank M. Schellenberg; Bruno M. La Fontaine, Editor(s)

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