Patent ID: 7475382

Claim:
A method for determining an assist feature configuration which specifies locations and dimensions for one or more assist features in a mask layout, the method comprising: receiving the mask layout; creating a set of candidate assist feature configurations; selecting a set of evaluation points in the mask layout; determining process-variation values at the set of evaluation points for the set of candidate assist feature configurations, wherein convolving the mask layout with the process-sensitivity model at an evaluation point in the mask layout generates a value that is indicative of the mask layout's sensitivity to process variations at the evaluation point, wherein determining the process-variation values includes: placing representative assist features in the mask layout based on a candidate assist feature configuration in the set of candidate assist feature configurations; evaluating process-variation values at the set of evaluation points by convolving the process-sensitivity model with the mask layout; and determining an improved assist feature configuration using the process-variation values, wherein determining the improved assist feature configuration using the process-variation values includes: formulating an optimization problem based on the process-variation values, wherein a solution to the optimization problem is associated with an assist feature configuration; computing a substantially optimal solution to the optimization problem; and determining the improved assist feature configuration based on the substantially optimal solution to the optimization problem; wherein placing assist features in the mask layout based on the improved assist feature configuration improves the mask layout's manufacturability; wherein using the process-sensitivity model to determine the improved assist feature configuration reduces an amount of computational time required to determine the improved assist feature configuration.