Patent ID: 8122388

Claim:
A machine-readable non-transitory medium containing instructions, which when operated on by the machine, causes the machine to perform a method of designing a set of two tiled masks for a dual exposure lithography operation, the method comprising: calculating a complex mask transmission at a numerical aperture (NA) that is twice the numerical aperture of an imaging tool to be used with said two tiled masks; splitting said complex mask transmission into a real part and an imaginary part; dividing, into tiles, product features that will share a common phase in each of the two tiled masks; following a traversal order to flip tiles to be at same locations on both tiled masks until a value of a merit function is reduced; and as measured by said merit function, calculating and weighting contour fidelity changes, due to edge movements and tile flipping, to generate a combined objective function, wherein said combined objective function may be used to balance sensitivity of said registration alignment error between said two tiled masks and said tile-flipping; and using a method to design each of the tiled masks which optimizes each of the tiled masks while holding the other of the tiled masks constant.