Patent ID: 8101324

Claim:
A photomask manufacturing method comprising: generating data of a main pattern to be transferred onto a substrate, and data of an assist pattern which is arranged adjacent to the main pattern and which assists the transfer of the main pattern without being transferred onto the substrate; performing optical proximity effect correction to the generated data of the main pattern, wherein corrected main pattern includes a first edge and a second edge, both the first edge and the second edge elongate to a first direction, the first edge faces to a first portion of a third edge of the assist pattern, and the second edge faces to a second portion of the third edge; correcting shapes of the main pattern and of the assist pattern on the basis of a shape change caused at an edge of the main pattern facing the assist pattern by the optical proximity effect correction; and forming a photomask by using the corrected data of the main pattern and of the assist pattern, wherein the process of correcting the shapes includes: detecting a level difference planarly between the first edge and the second edge; and moving at least one of the first edge and the second edge to a second direction perpendicular to the first direction in order to eliminate the level difference; moving at least one of the first portion of the third edge and the second portion of the third edge to the second direction, so as to enable the first edge and the second edge to be linearly transferred onto the substrate.