Patent ID: 8209641

Claim:
A method of fabricating a photomask used to form a lens, the method comprising the steps of: (a) generating mask pattern data, wherein a mask pattern for the lens comprises a plurality of grid cells, the step of generating the mask pattern data including: (i) acquiring transmitted light distribution data used to generate the photomask to fabricate the lens, the transmitted light distribution data including a quantity of light transmitted for each of the plurality of grid cells in the mask pattern; and (ii) determining whether to place a shield on each of the plurality of grid cells by binarizing, using an error diffusion method, the quantity of transmitted light in each of the plurality of grid cells, wherein the binarizing is performed in an order in which a distance from a center of the mask pattern to the grid cell whose quantity of transmitted light is to be binarized does not increase or does not decrease; and (b) fabricating the photomask based on the mask pattern data.