Complex layout features, especially two-dimensional (2D) features such as
jogs and corners, are more susceptible to photo-resist pinching and
bridging, even with the use of optical proximity correction. These
problems may arise due to unrealistic targets, e.g. square corners,
thereby resulting in excessively aggressive correction in the vicinity of
these 2D features. To provide a more realistic target, an aerial image
can be sampled and its gradient computed at evaluation points on the 2D
feature. The aerial image contains spatial information about the local
pattern and the interaction of the pattern with the manufacturing
process. This information can be used to predict a feasible shape or
curvature for the 2D feature. The predicted shape can then be used to
retarget the 2D feature based on realistic process capabilities.