| 摘要 |
A photomask is to be used for exposure of a semiconductor wafer with the dipole illumination light, and includes a main opening, a first assist opening, a second assist opening, a third assist opening and a fourth assist opening. Each of the assist openings is located so that the central point thereof is deviated from both of a first straight line parallel to a first direction and passing the central point of the main opening, and a second straight line parallel to a second direction and passing the central point of the main opening. Here, the first direction is the direction among in-plane directions of the photomask that is parallel to an alignment direction of an effective light source distribution of the dipole illumination light. Also, the second direction is the direction among in-plane directions of the photomask that is perpendicular to the alignment direction.
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