By T.A. Brunner, C. Fonseca, IBM SRDC, Hopewell Junction, New York
Simulations imply that narrow resist lines print best with a positive tone resist process while narrow trench geometries are best with a negative tone process, even if the resist performance parameters are unequal. Simple development bias models appear to capture this behavior accurately and are in agreement with full simulation.
Resist processes are now being tailored to specific feature types (e.g. contact holes or isolated lines) using such parameters as contrast, absorption, diffusion length, thickness, and development characteristics. Choice of resist tone is also a powerful means of optimizing a particular feature type, but one that is little used. Today, capable and mature positive tone processes dominate high resolution lithography. This paper will use simulation to explore process windows of various features for both tones of resist by assuming resists with similar characteristics .
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