Patent ID: 8045787

Claim:
A system for analyzing a mask topography, where an illumination system is configured to transmit light incident on a mask, wherein light passes through the mask to a projection system having a projection lens configured to transmit light to an image surface of a wafer, the system comprising a set of modules embodied in a tangible device and executable by at least one processor, the set of modules comprising: an initial E-field module configured to determine a first electric field on a mask surface of the mask using a Kirchhoff method, independent of a pitch formed on the mask, and to determine a second electric field on a pupil surface of the projection lens using an electromagnetic field analysis method dependent on the pitch; and a resultant E-field module configured to determine a third electric field on the image surface of the wafer as a combination of the first electric field and the second electric field, wherein the initial E-field module is configured to determine the second electric field for each of a plurality of pitches, to obtain amplitudes and phases for the plurality of pitches, and, if amplitudes and phases cannot be obtained for one or more pitches, to determine the amplitudes and phases for the one or more pitches based on the amplitudes and phases for the other pitches.