Patent ID: 8627245

Claim:
A method of designing an integrated circuit (IC) layout for a multiple patterning layout fill process using at least one computing device, the method comprising: providing a pre-characterized mask tile library including a plurality of distinct mask tiles each having a distinct mask density on a plurality of distinct exposures each associated with a patterning process in the multiple patterning process; determining a density of a mask group in a first layout window in the IC layout, the first layout window including an open space unfilled by the mask group; and selecting a set of mask tiles from the plurality of distinct mask tiles to fill a portion of the open space using the at least one computing device, the selecting based upon the determined density of the mask group in the first layout window and the distinct mask density of the selected set of mask tiles on the plurality of distinct exposures, wherein the selecting of the set of mask tiles from the plurality of distinct mask tiles to fill the portion of the open space includes: determining a total area of the mask group in the first layout window; calculating a total shape density of the mask group in the first layout window; calculating a relative density of the plurality of distinct mask tiles each associated with the patterning process in the multiple patterning process; comparing the total shape density of the mask group to a predetermined density threshold for the first layout window; comparing a shape density of a candidate set of mask tiles from the plurality of distinct mask tiles with a difference between the predetermined density threshold for the first layout window and the shape density of the mask group; and selecting the candidate set of mask tiles for insertion in the first layout window in response to determining the shape density of the candidate set does not exceed the difference between the predetermined density threshold and the shape density of the mask group, wherein the selecting of the candidate set of mask tiles reduces an imbalance of densities between the plurality of distinct exposures.