| 摘要 |
A photo mask includes an asymmetrical diffraction grating pattern in which diffraction efficiencies of plus primary diffracted light and minus primary diffracted light are different, the asymmetrical diffraction grating pattern including a shielding portion which shields light, a first transmitting portion which transmits light, and a second transmitting portion which transmits light, a ratio of widths of the shielding portion, the first transmitting portion, and the second transmitting portion being n11 where n is a positive real number except 2, the asymmetrical diffraction grating pattern approximately satisfying 163�<=360�/(n+2)+theta<=197� where theta (90�) indicates an absolute value of a difference between a phase of the light transmitted through the first transmitting portion and that of the light transmitted through the second transmitting portion, and a reference pattern for obtaining an image as a reference for measuring a shift of an image of the asymmetrical diffraction grating pattern. |
