Patent ID: 8959462
Filing Date: 2015-02-17
Classification: G03F

Abstract:
1. A method for manufacturing a mask comprising the steps of: generating an optical domain representation from a design pattern and an imaging light; and optimizing said optical domain representation under a constraint that values of negative excursions at predetermined evaluation points must be greater than or equal to predetermined negative threshold values assigned to said predetermined evaluation points; wherein: said optical domain representation is a variable representation of a wavefront; said imaging light is light that is transmitted through said mask; said negative excursions are in an object domain representation of said optical domain representation; said predetermined evaluation points are in said object domain representation; said predetermined negative threshold values are determined as a function of distances from a feature edge of said mask; outside of the feature, said function specifies that a negative threshold value for a first distance is smaller than a negative threshold value for a second distance that is larger than the first distance; and at least one of the steps is carried out by a computing device.