A method for
mask data preparation (MDP) is disclosed, in which a set of shots is determined that will form a pattern on a
reticle, where the determination includes calculating the pattern that will be formed on a substrate using an optical lithographic process with a
reticle formed using the set of shots. A method for
optical proximity correction (OPC) or MDP is also disclosed, in which a preliminary set of
charged particle beam shots is generated using a preliminary
mask model, and then the shots are modified by calculating both a
reticle pattern using a final
mask model, and a resulting substrate pattern. A method for OPC is also disclosed, in which an ideal pattern for a
photomask is calculated from a desired substrate pattern, where the model used in the calculation includes only optical
lithography effects and / or substrate
processing effects.