During the past few years, new technology brought about new problems we face today due to
shrinkage of the feature size. Some of the problems such as Mask Error Enhancement Factor (MEEF), overlay
control, and so on are crucial because large MEEF can make it difficult to satisfy CD target, and bring about
large CD variation. Moreover, it can also lead to degraded CD uniformity which would have an undesired
influence on device properties. Recently, 2-D random contact hole is getting crucial because it normally has
very large MEEF and cause asymmetric proximity effect which can cause large CD variation, and
misalignment of layer-to-layer. In other words, the method of optical proximity correction and building
accurate OPC model for 2-D random contact hole pattern could be key factor obtaining better CD uniformity
with enhanced overlay margin. Furthermore, in order to get very tangible performance, design based
metrology system (DBM) is used to evaluate process performance. Design based metrology systems are able
to extract information of whole chip CD variation. On top of that, OPC abnormality can be identified and
design feedback can be also disclosed.
In this paper, we will investigate novel method for sub 45nm 2-D random contact hole printing.
First, optical proximity effect (OPE) for two dimensional layout will be investigated. Second, the results of
Variable Threshold Modeling (VTM) for various slit contact hole patterns will be analyzed. Third, model
based verification will be done and analyzed through full-chip before creating full-chip mask. Finally, sub
45nm 2-D random contact hole printing performance will be presented by DBM.