Method for correcting optical proximity effects in a lithographic process using the radius of curvature of shapes on a mask

A method of correcting proximity errors in a lithographic process on a mask comprising the steps of:

• providing at least one polygon on the said mask;
• providing at least one curved shape to approximate the contour of a polygon on said mask, said polygon controlling the contour of said at least one curved shape;
• assigning to each side of said polygon at least one edge segment representing the shape of said polygon side;
• forming corners of said polygon by intersection of adjacent and non-colinear sets of said edge segments;
• assigning to each of said edge segments and to each of said corners a radius of curvature;
• assigning to each of said radius of curvature a maximum allowable limit by providing predetermined minimum and maximum values;
• iteratively modifying said radii of curvature of each side and corner of said polygon until said maximum allowable limit is reached, wherein said at least one curved shape reaches the shape of the original polygon;
• and
• forming a closed contour that approximates said polygon by joining said curved segments corresponding to adjacent sides of said polygon.

A program storage device readable by a machine, tangibly embodying a program of instructions executable by the machine to perform method steps for correcting proximity errors of a lithographic process on a mask used in the said lithographic process, said method steps comprising:

• providing at least one curved shape to approximate the contour of a polygon on said mask, said polygon controlling the contour of said at least one curved shape;
• assigning to each side of said polygon at least one edge segment representing the shape of said polygon side;
• forming corners of said polygon by intersection of adjacent and non-colinear sets of said edge segments;
• assigning to each of said edge segments and to each of said corners a radius of curvature;
• assigning to each of said radius of curvature a maximum allowable limit by providing a minimum and a maximum value;
• and
• iteratively modifying said radii of curvature of each side and corner of said polygon until said maximum allowable limit is reached, wherein said at least one curved shape reaches the shape of the original polygon.