1. A method of correcting an optical proximity effect, comprising: fabricating a test mask having test patterns; forming wafer patterns on a wafer using the test mask; measuring line widths of the wafer patterns formed on the wafer; executing a model calibration using the measured line widths; writing a correction recipe using the model calibration; dividing an entire area of the wafer into a plurality of templates; executing an optical proximity correction using the correction recipe on one of the plurality of templates; verifying whether the optical proximity correction completed on a different template was properly executed, wherein the verifying step is executed in parallel with the executing an optical proximity correction step; merging data on the corrected templates that pass the verification and writing final data based on merged data; and fabricating a photomask using the final data.