Effect of Wetting Time on CD Uniformity in Immersion Lithography

IBM Systems and Technology Group
Implication for CD Variation in Immersion Lithography
� Spatial distribution <strong>of</strong> wetting (elution) time across the wafer
during immersion exposure is non-uniform
� Impact <strong>of</strong> short duration wetting on resist CD and pr<strong>of</strong>ile is
not very well characterized
� Non-uniform wetting could contribute to CD variation
� To quantify such an effect, detailed analysis <strong>of</strong> the immersion
process as well as precision metrology is necessary
Reference: I. Pollentier et al, “Resist Pr<strong>of</strong>ile Control in Immersion Lithography using Scatterometry
Measurements”, Proc. SPIE, Vol. 5754, p11 (2005)
4 <strong>Effect</strong> <strong>of</strong> <strong>Wetting</strong> <strong>Time</strong> on CDU - Kaushal Patel September 13, 2005
© 2003 IBM Corporation