Mask alignment mark, photomask, exposure apparatus, exposure method, and manufacturing method of device
View Patent ↗According to one embodiment, there is provided a mask alignment mark disposed on a photomask irradiated by an illumination optical system with illumination light from a direction inclined with respect to an optical axis and used to form a latent image on a substrate through a projection optical system. The mask alignment mark including a plurality of patterns arranged in a predetermined direction at a pitch of substantially P=λ/{2×(1−σ)×(LNA)}, where σ is a ratio of a numerical aperture INA of illumination light incident on the photomask from the illumination optical system to a numerical aperture LNA of an object side of the projection optical system (INA)/(LNA), and λ is a wavelength of light.
1. A mask alignment mark disposed on a photomask irradiated by an illumination optical system with illumination light from a direction inclined with respect to an optical axis and used to form a latent image on a substrate through a projection optical system, the mask alignment mark comprising:
a plurality of patterns arranged in a predetermined direction at a pitch of substantially
P=λ/{ 2×(1−σ)×(LNA)}
where σ is a ratio of a numerical aperture INA of illumination light incident on the photomask from the illumination optical system to a numerical aperture LNA of an object side of the projection optical system (INA)/(LNA), and λ is a wavelength of light.
2. The mask alignment mark according to claim 1 , wherein
the plurality of patterns includes a plurality of line patterns.
3. The mask alignment mark according to claim 1 , wherein
the mask alignment mark is used for alignment of the photomask and the substrate.
4. A photomask comprising the mask alignment mark according to claim 1 .
5. The photomask according to claim 4 , further comprising:
an effective exposure area; and
a peripheral area surrounding the effective exposure area, wherein
the mask alignment mark is disposed in the peripheral area.
6. A photomask comprising a plurality of mask alignment marks, each according to claim 1 .
7. The photomask according to claim 6 , further comprising:
an effective exposure area; and
a peripheral area surrounding the effective exposure area, wherein
each of the plurality of mask alignment marks is disposed in the peripheral area.
8. The photomask according to claim 7 , wherein
the plurality of mask alignment marks includes:
a first mask alignment mark disposed in the peripheral area; and
a second mask alignment mark disposed at a separated position interposing the effective exposure area in the peripheral area.
9. The photomask according to claim 8 , wherein
the first mask alignment mark and the second mask alignment, mark are disposed at point-symmetrical positions to each other about a point in the effective exposure area.
10. The photomask according to claim 9 , wherein
the first mask alignment mark and the second mask alignment mark are disposed at line-symmetrical positions to each other about a line passing through a center of the effective exposure area.
11. An exposure apparatus comprising:
the photomask according to claim 4 including an effective exposure area and a peripheral area surrounding the effective exposure area, and a mask alignment mark being disposed in the peripheral area; and
a substrate stage holding a substrate and including a substrate holding area corresponding to the effective exposure area and a second peripheral area surrounding the substrate holding area, and an optical sensor being disposed at a position corresponding to the mask alignment mark in the second peripheral area.
12. An exposure apparatus comprising:
a photomask according to claim 6 including an effective exposure area and a peripheral area surrounding the effective exposure area, and a plurality of mask alignment marks being disposed in the peripheral area; and
a substrate stage holding a substrate and including a substrate holding area corresponding to the effective exposure area and a second peripheral area surrounding the substrate holding area, and a plurality of optical sensors being disposed at a position corresponding to the plurality of mask alignment marks in the second peripheral area.
13. The exposure apparatus according to claim 12 , wherein
the plurality of mask alignment marks includes:
a first mask alignment mark disposed in the peripheral area; and
a second mask alignment mark disposed at a separated position interposing the effective exposure area in the peripheral area, and
the plurality of optical sensors includes:
a first optical sensor disposed at a position corresponding to the first mask alignment mark in the second peripheral area; and
a second optical sensor disposed at a position corresponding to the second mask alignment mark in the second peripheral area.
14. The exposure apparatus according to claim 13 , wherein
the first mask alignment mark and the second mask alignment, mark are disposed at point-symmetrical positions to each other about a point in the effective exposure area, and
the first optical sensor and the second optical sensor are disposed at substantially point-symmetrical positions to each other about a point in the substrate holding area.
15. The exposure apparatus according to claim 14 , wherein
the first mask alignment mark and the second mask alignment mark are disposed at line-symmetrical positions to each other about a line passing through a center of the effective exposure area, and
the first optical sensor and the second optical sensor are disposed at substantially line-symmetrical positions to each other about a line passing through a center of the substrate holding area.
16. The exposure apparatus according to claim 12 , further comprising:
an illumination optical system capable of illuminating the photomask with illumination light, from a direction inclined with respect to an optical axis; and
a projection optical system that projects light from the photomask on the substrate.
17. An exposure method comprising:
setting an illumination condition in which a photomask is irradiated with illumination light from a direction inclined with respect to an optical axis; and
performing alignment of the photomask and the substrate using a mask alignment mark having a plurality of patterns under the illumination condition, wherein
the plurality of patterns is disposed on the photomask used to form a latent image on a substrate through a projection optical system and arranged in a predetermined direction at a pitch of substantially
P=λ/{ 2×(1−σ)×(LNA)}
where σ is a ratio of a numerical aperture INA of illumination light incident on the photomask from the illumination optical system to a numerical aperture LNA of an object side of the projection optical system (INA)/(LNA), and λ is a wavelength of light.
18. The exposure method according to claim 17 , further comprising
exposing the substrate by the illumination optical system and the illumination optical system under the illumination condition.
19. The exposure method according to claim 18 , further comprising
performing focus control under the illumination condition, wherein
the exposing is performed while the focus control is being performed.
20. A manufacturing method of device comprising:
exposing a substrate with the exposure method according to claim 17 ; and
developing the exposed substrate.