Adjustable dummy fill

Abstract

A method of placing a dummy fill layer on a substrate is disclosed (FIG. 2 ). The method includes identifying a sub-region of the substrate ( 210 ). A density of a layer in the sub-region is determined ( 212 ). A pattern of the dummy fill layer is selected to produce a predetermined density ( 216 ). The selected pattern is placed in the subregion ( 208 ).

What is claimed is: 
     
         1 . A method of placing a dummy fill layer on a substrate, comprising:
 determining a global target layer density;   identifying a plurality of sub-regions of the substrate;   determining a local target density of a layer in each respective sub-region;   selecting a first pattern of the dummy fill layer to place in a first of the plurality of sub-regions; and   selecting a second pattern of the dummy fill layer to place in a second of the plurality of sub-regions.   
     
     
         2 . A method as in  claim 1 , comprising:
 identifying a blocking area of the substrate; and   identifying the plurality of sub-regions of the substrate apart from the blocking area.   
     
     
         3 . A method as in  claim 1 , comprising:
 partitioning the substrate into plural subregions including the first and second sub-region; and   determining a local target density of the layer in each respective sub-region.   
     
     
         4 . A method as in  claim 1 , wherein a final local target layer density of the first sub-region is within 10 percent of a final local target layer density of the second the sub-region. 
     
     
         5 . A method as in  claim 1 , wherein the first pattern of the dummy fill layer is placed in the first of the plurality of sub-regions in a single step. 
     
     
         6 . A method as in  claim 1 , wherein the second pattern is iteratively selected to produce a desired final local target layer density of the second sub-region.