Method and apparatus for testing a photomask

A method of testing a digital representation of a photomask usable to construct a physical instance of the photomask, comprising:

• a) selecting a particular region of the photomask as represented by the digital representation;
• b) identifying a pattern type present in the particular region to characterize the particular region;
• c) determining a lithographic process stress condition for the particular region, considering the pattern type;
• d) determining a result of lithographically patterning a feature by simulating a photolithographic exposure using the particular region of the photomask under the lithographic process stress condition;
• and
• e) deciding whether the particular region of the photomask is acceptable based on the result of the simulated exposure only under the lithographic process stress condition.

An apparatus for performing a method of testing a photomask, the apparatus including a processor, the processor being operable to a) select a particular region of a photomask;

• b) identify a pattern type present in the particular region to characterize the particular region;
• c) determine a lithographic process stress condition for the particular region in consideration of the pattern type;
• d) determine a result of lithographically patterning a feature by simulating a photolithographic exposure using the particular region of the photomask under the lithographic process stress condition;
• and e) determine whether the particular region of the photomask is acceptable based on the result of the simulated exposure only under the lithographic process stress condition.