Subresolution grating for attenuated phase shifting mask fabrication
First Claim
Patent Images
1. A photomask comprising:
- a primary pattern; and
a diffraction grating about the primary pattern, the diffraction grating including contact shapes approximating a circle, the contact shapes being less than 0.11 microns in diameter.
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Abstract
A subresolution grating composed of approximately circular contacts is fabricated around the border of the primary pattern of a photomask. As a result, resolution at the edges of the photomask pattern is improved when the pattern is printed on a wafer surface. In addition, the reduced leakage enables a more efficient use of the glass plate on which the photomask is fabricated as well as a more efficient use of the wafer surface as a result of being able to place patterns closer together.
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Citations
22 Claims
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1. A photomask comprising:
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a primary pattern; and
a diffraction grating about the primary pattern, the diffraction grating including contact shapes approximating a circle, the contact shapes being less than 0.11 microns in diameter. - View Dependent Claims (2)
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3. A photomask comprising:
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a primary pattern; and
a diffraction grating outside the primary pattern, the diffraction grating having octagonal contacts each with a diameter, the octagonal contacts being separated from each other by a distance substantially equal to the diameter. - View Dependent Claims (4, 5)
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6. A photomask comprising:
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a primary pattern; and
a diffraction grating outside the primary pattern, the diffraction grating including approximately circular contacts having substantially equal diameters and distances therebetween, the diameters and distances being less than 0.11 microns. - View Dependent Claims (7)
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- 8. A method of fabricating a border surrounding the primary pattern of a photomask comprising depositing a pattern of attenuating material on the photomask, the pattern including substantially circular contact shapes having a diameter of less than 0.11 micron.
- 10. A method of fabricating a border surrounding the primary pattern of a photomask comprising depositing a pattern of attenuating material on the photomask, the pattern including contact shapes that approximate a circle having a diameter of less than 0.11 micron.
- 12. A method of fabricating a border surrounding the primary pattern of a photomask comprising depositing a pattern of attenuating material on the photomask, the pattern including octagonal contact shapes.
- 14. A method of projecting a pattern on a wafer comprising projecting light through a photomask having a diffraction grating about a perimeter of a primary pattern, the diffraction grating comprising octagonal contacts.
- 17. A method of projecting a pattern on a wafer comprising projecting light through a photomask having a diffraction grating that includes octagonal features at equidistant intervals.
- 19. A method of projecting a pattern on a wafer comprising projecting light through a photomask having a diffraction grating that includes substantially circular features at equidistant intervals.
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21. A method of projecting a pattern on a wafer comprising:
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projecting light through a photomask having a diffraction grating that includes substantially circular features at equidistant intervals of less than 0.11 micron, the substantially circular features having diameters equal to the intervals;
stepping the photomask across a plurality of locations on the wafer; and
for each of the plurality of locations on the wafer, projecting light through the photomask. - View Dependent Claims (22)
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Specification