Defect probability of directed self-assembly lithography: Fast identification and post-placement optimization

In directed self-assembly lithography (DSAL), an inter-cell cluster of contacts, which crosses the boundary of cells, is more likely to cause patterning failure because corresponding guide pattern (GP) has not been verified beforehand. All forms of inter-cell clusters can systematically be identified and grouped, which allows us to define DSA defect probability when two arbitrary cells are placed side by side. We then address post-placement optimization, in which some cells are flipped and some cells are swapped with their adjacent cells so that the number of whitespaces inserted in between cell pairs of high defect probability is minimized. Experiments with a few test circuits demonstrate 11% increase of placement density, on average, with no expected DSA defects.