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Publication
SPIE Advanced Lithography 2011
Conference paper
Revisit pattern collapse for 14nm node and beyond
Abstract
In this study, we have analyzed new data sets of pattern collapse obtained from 300 mm wafers which were coated with a process-of-record (POR) EUV resist and exposed by an EUV Alpha-Demo tool (ADT) and a Vistec VB300 e-beam exposure tool. In order to minimize any processing effects on pattern collapse, the same POR EUV track process was applied to both exposures. A key metric of our analysis is the critical aspect ratio of collapse (CARC)1. We found that CARC of POR EUV resist decreases monotonically with spacing, in the range of ∼1.8-2.2 at ∼32-54 nm space (60-80 nm pitch) for EUV, and ∼1.5-2.1 at ∼16-50 nm space (∼46-80 nm pitch) for e-beam. We also estimated an apparent Young's modulus of POR EUV resist by fitting a collapse model2 to the CARC data. The resulting modulus ∼0.30 GPa was much smaller than the modulus of typical polymer glasses (∼1.0-5.0 GPa). Our findings suggest that due to a significant decrease of resist mechanical properties and a sharp increase in capillary force, it will be challenging to maintain aspect ratios above 2.0 for sub-30 nm resist spacing (sub-60 nm pitches). For patterning at these dimensions, alternate processes and materials will become increasingly necessary, e.g. surfactant-based rinse solutions 3 and other approaches. © 2011 SPIE.