Patent ID: 8156451

Claim:
A method of manufacturing a photomask comprising the steps of: (a) calculating a photomask manufacturing load index based on a photomask manufacturing difficulty level; (b) manufacturing the photomask by: a lithography step performed by a photomask lithography device; a defect inspection step performed by a defect inspection device; and a defect correction step performed by a defect correction device, wherein the step (a) comprises a step of (a1) analyzing a mask layout, the photomask manufacturing load index includes at least one of a defect guarantee load index and a lithography load index, the defect guarantee load index is a first function to be determined based on: a number of errors as the number of patterns to be problematic in the photomask manufacturing extracted in the step (a1); and a priority of patterns arranged in the mask layout, the lithography load index is a second function to be determined based on: a total number of Shots per a semiconductor chip, where a unit of lithography of the photomask lithography device is defined as a Shot; and an area of the semiconductor chip, and in the step (a1), the mask layout is analyzed based on an analysis previously set so that the patterns to be problematic in the photomask manufacturing are extracted, and further the total number of Shots per the semiconductor chip is computed, wherein information of the patterns to be problematic in the photomask manufacturing is analyzed so that a density distribution of the Shots is computed, and when the density of the Shot is high and exceeds a memory limit in the desired photomask lithography device, another photomask lithography device is selected so as not to exceed the memory limit.