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Proceedings Paper

A methodology for the characterization of topography induced immersion bubble defects
Author(s): Michael Kocsis; Peter De Bisschop; Mireille Maenhoudt; Young-Chang Kim; Greg Wells; Scott Light; Tony DiBiase
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Paper Abstract

A key issue regarding the introduction of 193nm immersion lithography into production is immersion specific defects. One of these new defect types is the formation of air bubbles in the immersion fluid near or on the resist surface, which can then cause significant local dose variations. One possible mechanism for inducing bubble formation is the introduction of surface topography, such as seen on a typical product wafer, which could then disrupt the immersion fluid flow and entrain air. This brings up the question of what, if any, types of topography we need to be worried about and how do we test all the possible variants that will exist on product wafers. To help address this issue we have created a special topography reticle and wafer set and used them for exposures on a prototype immersion scanner. The wafer set was generated using a first level reticle designed to have an extremely wide range of topography types in a modular and systematically varying format. The wafer fabrication included skews of the trench depths, variation of the surface contact angle by using different topcoats, and optimization of the process flow to enable high contrast defect inspections. The second level reticle used for the immersion exposures was designed to cover the entire topography wafer with dose sensitive grating structures to detect any dose modulation caused by bubbles. In this paper we present the design of these reticles and wafers and the results of the first immersion exposures. Flat, unpatterned wafers were also exposed on the immersion tool in order to provide a basis for comparison. A KLA 2351 inspection tool was used to inspect all the wafers for defects. The initial results of these tests did not show a strong interaction of bubbles with topography.

Paper Details

Date Published: 12 May 2004
PDF: 10 pages
Proc. SPIE 5754, Optical Microlithography XVIII, (12 May 2004); doi: 10.1117/12.599329
Show Author Affiliations
Michael Kocsis, IMEC (Belgium)
Sematech (United States)
Intel Corp. (United States)
Peter De Bisschop, IMEC (Belgium)
Mireille Maenhoudt, IMEC (Belgium)
Young-Chang Kim, IMEC (Belgium)
Greg Wells, IMEC (Belgium)
Texas Instruments (United States)
Scott Light, IMEC (Belgium)
Micron Technology (United States)
Tony DiBiase, KLA-Tencor (United States)

Published in SPIE Proceedings Vol. 5754:
Optical Microlithography XVIII
Bruce W. Smith, Editor(s)

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