Opportunities and Challenges in Immersion Lithography

At IMEC, one of the first full field 193nm immersion scanners has been installed, i.e. a XT:1250Di with maximum NA=0.85. Immersion tools are expected to show the same stability and control as the equivalent dry systems. Therefore CDU, focus and overlay control are being evaluated. New aspects arise...

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Bibliographic Details
Published in:Journal of Photopolymer Science and Technology 2005, Vol.18(5), pp.571-577
Main Authors: Meanhoudt, M., Vandenberghe, G., Ercken, M., Cheng, S., Leunissen, P., Ronse, K.
Format: Article
Language:English
Subjects:
193nm immersion lithography
defectivity
hyper NA
resist
RET
top coat
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Summary:At IMEC, one of the first full field 193nm immersion scanners has been installed, i.e. a XT:1250Di with maximum NA=0.85. Immersion tools are expected to show the same stability and control as the equivalent dry systems. Therefore CDU, focus and overlay control are being evaluated. New aspects arise with respect to photoresist processing and defectivity due to the interaction with water, such as leaching and water uptake. Resists need to be optimized for this, and in the mean time immersion top coats are introduced to overcome these issues. These top coats prevent leaching of resist components, but can show new problems such as the occurrence of a mixing layer with the resist or a soaking fingerprint. Resolution enhancement techniques need to be reconsidered taking into account the better process latitudes and imaging performance caused by immersion. As immersion will lead to the introduction of NA's larger than 1, simulation studies are started to understand the impact of high incident angles on the mask level such as the effect of mask topography and polarization.
ISSN:0914-9244
1349-6336
DOI:10.2494/photopolymer.18.571