Area fill generation with inherent data volume reduction

Control of variability and performance in the back end of the VLSI manufacturing line has become extremely difficult with the introduction of new materials such as copper and low-k dielectrics. Uniformity of chemical-mechanical planarization (CMP) requires the insertion of area fill features into the layout, in order to smoothen the variation of feature densities across the die and thus improve manufacturability. Because the size of area fill features is very small compared with the large empty layout areas that must be filled, the filling process can increase the size of a GDSII file by an order of magnitude or more. Data compression is therefore a significant issue in successful fill synthesis. In this paper, we introduce compressed fill strategies which exploit the GDSII array reference record (AREF) construct. We apply greedy and linear programming based optimization techniques, and obtain practical compressed filling solutions.