Patent ID: 8730452
Filing Date: 2014-05-20
Classification: G03F,G06T

Abstract:
1. A method of obtaining a target source and a target mask comprising the steps of: determining how an illumination is provided from an illumination source included with an illumination system to a plurality of source points and a mask corresponding to a predetermined mask pattern; selecting fragmentation points in an image plane of an image formed by the illumination provided to the predetermined mask pattern; determining an intensity and image log slope of illumination at each fragmentation point; calculating a predetermined intensity range based on the illumination system's specifications; and changing the intensity and shape of the illumination source and the magnitude and phase of diffraction orders of the mask to form an image in the image plane that maximizes the minimum image log slope at the fragmentation points while forcing the intensity at the fragmentation points to be within the predetermined intensity range, thereby obtaining the target source and the target mask from the changed illumination source and mask, respectively.