Patent ID: 7971160
Filing Date: 2011-06-28
Classification: G03F,H01L

Abstract:
1. A method executed by a computer for creating a pattern on a photomask, the method comprising: recognizing spaces between main patterns by using pattern data which indicate the main patterns to be adjacently transferred onto a wafer, classifying the spaces between the main patterns into two or more groups, integrating the number of appearance times of the spaces between main patterns in each group, and specifying one or more groups on the basis of the number of appearance times of the space between main patterns; determining a 1st rule about arrangement of a 1st assist pattern on the photomask in accordance with the spaces which are specified by the one or more groups, the 1st assist pattern being adjacent to the main patterns and not being transferred onto the wafer; creating 1st pattern data on the basis of the 1st rule; estimating a depth of focus in the presence of the 1st assist pattern among the main patterns; determining a 2nd rule about arrangement of a 2nd assist pattern on the photomask to improve the depth of focus in the presence of the 1st assist pattern among the main patterns in accordance with the spaces which are specified by the one or more groups, the 2nd assist pattern being adjacent to the main patterns and not being transferred onto the wafer; creating a 2nd assist pattern data on the basis of the 2nd rule, and arranging a 2nd assist pattern by using the 2nd assist pattern data on the photomask.