Optical proximity correction (OPC) method for improving lithography process window

摘要

A method is described for applying Optical Proximity Correction to corners and line ends in a pattern having critical dimensions in the sub micron region. Segments of curves are used to approximate corners and line ends in a pattern. The normal vector to the curve and area vector are then determined for all points on the segment of the curve used to approximate the pattern feature. The area vector has the same direction as the normal vector and a magnitude equal to the distance between the curve and the undistorted pattern. An optical proximity correction vector is then determined as the sum of a first scaler function multiplied by the unit normal vector and a second scaler function multiplied by the area vector. Next an optimum optical proximity correction shape is determined by moving the curve a distance and direction equal to the optical proximity correction vector. The optimum proximity correction shape is then approximated using regular geometric shapes, rectangles and triangles, to form an optical proximity corrected pattern. A mask of the optical proximity corrected pattern can be formed using electron beam methods without requiring excessive electron beam time.