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Delays in equipment availability for both Extreme UV and High index immersion have led to a growing
interest in double patterning as a suitable solution for the 22nm logic node. Double patterning involves
decomposing a layout into two masking layers that are printed and etched separately so as to provide the
intrinsic manufacturability of a previous lithography node with the pitch reduction of a more aggressive
node. Most 2D designs cannot be blindly shrunk to run automatically on a double patterning process and so
a set of guidelines for how to layout for this type of flow is needed by designers. While certain classes of
layout can be clearly identified and avoided based on short range interactions, compliance issues can also
extend over large areas of the design and are hard to recognize. This means certain design practices should
be implemented to provide suitable breaks or performed with layout tools that are double patterning
compliance aware. The most striking set of compliance errors result in layout on one of the masks that is at
the minimum design space rather than the relaxed space intended. Another equally important class of
compliance errors is that related to marginal printability, be it poor wafer overlap and/or poor process
window (depth of focus, dose latitude, MEEF, overlay). When decomposing a layout the tool is often
presented with multiple options for where to cut the design thereby defining an area of overlap between the
different printed layers. While these overlap areas can have markedly different topologies (for instance the
overlap may occur on a straight edge or at a right angled corner), quantifying the quality of a given overlap
ensures that more robust decomposition solutions can be chosen over less robust solutions. Layouts which
cannot be decomposed or which can only be decomposed with poor manufacturability need to be
highlighted to the designer, ideally with indications on how best to resolve this issue. This paper uses an
internally developed automated double pattern decomposition tool to investigate design compliance and
describes a number of classes of non-conforming layout. Tool results then provide help to the designer to
achieve robust design compliant layout.
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