US Patent 8972229 Fast 3D mask model based on implicit countors

Computer-readable medium and methods for photolithographic simulation of scattering. A design layout comprising a layout polygon is received. A skeleton representation of a mask shape that is created responsive to e-beam writing of the layout polygon is generated. The skeleton representation is defined by a plurality of skeleton points. Individual scattering patterns for the skeleton points are selected from a lookup table of pre-determined scattering patterns. Each of the individual scattering patterns representing an amount of optical scattering for a corresponding one of the skeleton points. A simulated wafer image is produced responsive to the individual scattering patterns.