Patent ID: 7966585

Claim:
A method comprising: receiving data representing a number of polygons that define a target pattern of features to be printed on a wafer with a first mask and a second mask; using a computer, analyzing the data to locate first features, or portions thereof, which are oriented in a first direction; analyzing the data to locate second features, or portions thereof, which are not oriented in the first direction; creating data for the first mask by expanding polygons corresponding to the first features, or portions thereof, but not expanding polygons corresponding to the second features, or portions thereof, wherein the expanding is calculated to create a shield for the first features when printing on the wafer using the first mask; and creating data for the second mask by expanding polygons corresponding to the second features, or portions thereof, but not expanding polygons corresponding to the first features, or portions thereof, wherein the expanding is calculated to create a shield for the second features when printing on the wafer using the second mask.