Atom lithographic mask having diffraction grating aligned with primary mask pattern
First Claim
1. A lithographic mask comprising:
- a transparent substrate having a first side and a second side separated by a thickness of the substrate;
a mask pattern comprising a patterned opaque layer formed on the first side of the substrate; and
a diffraction grating formed on the second side of the substrate in alignment with at least a portion of the mask pattern, the diffraction grating comprising a pattern of phase shift grooves etched in the second side of the substrate to a depth selected to diffract and phase shift exposure energy transmitted through the phase shift grooves relative to exposure energy transmitted through adjacent full thickness portions of the substrate to provide off axis illumination for the mask pattern.
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Accused Products
Abstract
An ATOM lithographic mask includes a transparent substrate having both a primary mask pattern and a diffraction grating. The diffraction grating includes chromeless phase shifters configured to diffract exposure energy directed through the substrate to provide off axis illumination for the primary mask pattern. The primary mask pattern can include a patterned opaque layer having an alignment mark formed therein. The alignment mark can be used during fabrication of the mask for accurately aligning the grating pattern and the primary mask pattern. Because of the accurate alignment, the layout, orientation and pitch of the diffraction grating with respect to the primary mask pattern, can be selected to optimize image formation from the mask pattern.
79 Citations
36 Claims
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1. A lithographic mask comprising:
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a transparent substrate having a first side and a second side separated by a thickness of the substrate; a mask pattern comprising a patterned opaque layer formed on the first side of the substrate; and a diffraction grating formed on the second side of the substrate in alignment with at least a portion of the mask pattern, the diffraction grating comprising a pattern of phase shift grooves etched in the second side of the substrate to a depth selected to diffract and phase shift exposure energy transmitted through the phase shift grooves relative to exposure energy transmitted through adjacent full thickness portions of the substrate to provide off axis illumination for the mask pattern. - View Dependent Claims (2)
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3. A lithographic mask comprising:
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a transparent substrate having a first side and a second side separated by a thickness of the substrate; a mask pattern comprising a patterned opaque layer formed on the first side of the substrate; an alignment mark formed in the opaque layer; and a diffraction grating comprising a plurality of phase shift grooves formed on the second side of the substrate in alignment with the alignment mark, the diffraction grating comprising a pattern of phase shift grooves etched in the second side of the substrate to a depth selected to diffract and phase shift exposure energy transmitted through the phase shift grooves relative to exposure energy transmitted through adjacent full thickness portions of the substrate, to provide off axis illumination for the mask pattern. - View Dependent Claims (4, 5, 6, 7, 8)
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9. A lithographic mask comprising:
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a transparent substrate having a first side and a second side; an opaque layer formed on the first side of the substrate; and a pattern of phase shift members formed on the second side of the substrate, the phase shift members comprising a transparent, patterned phase layer deposited on the second side to a thickness selected to phase shift and diffract exposure energy directed through the phase shift members relative to exposure energy directed through adjacent portions of the substrate to provide off axis illumination of the mask pattern. - View Dependent Claims (10, 11)
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12. A lithographic mask comprising:
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a substrate having a first side and a second side; a primary mask pattern formed on the first side of the substrate comprising a patterned opaque layer having an alignment mark therein; and a pattern of phase shift members formed on the second side of the substrate in alignment with the alignment mark and selected portions of the primary mask pattern, the phase shift members comprising a transparent, patterned phase layer deposited on the second side to a thickness selected to phase shift and diffract exposure energy directed through the phase shift members relative to exposure energy directed through adjacent portions of the substrate to provide diffracted exposure energy for the primary mask pattern. - View Dependent Claims (13, 14, 15, 16, 17)
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18. A method for fabricating a lithographic mask comprising:
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providing a transparent substrate having a first side and a second side separated by a thickness of the substrate; forming an opaque layer on the first side of the substrate; forming an alignment mark in the opaque layer; forming a diffraction grating on the second side of the substrate in alignment with the alignment mark, the diffraction grating comprising a pattern of phase shift grooves etched in the second side of the substrate to a depth selected to diffract and phase shift exposure energy transmitted through the phase shift grooves relative to exposure energy transmitted through adjacent full thickness portions of the substrate; and forming a primary mask pattern in the opaque layer having at least a portion thereof in alignment with the alignment mark and the diffraction grating. - View Dependent Claims (19)
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20. A method for fabricating a lithographic mask comprising:
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providing a transparent substrate; forming an opaque layer on a first side of the substrate with a first alignment mark; depositing a layer of resist on a second side of the substrate; forming a second alignment mark in the layer of resist in alignment with the first alignment mark; forming a resist mask by exposing a diffraction pattern on the layer of resist with a mask writer configured to view the second alignment mark and align the diffraction pattern with the second alignment mark; forming a diffraction grating corresponding to the diffraction pattern on the second side of the substrate using the resist mask; and forming a mask pattern in the opaque layer by depositing a second layer of resist on the opaque layer and exposing the mask pattern in alignment with the diffraction grating using the mask writer. - View Dependent Claims (21, 22, 23, 24, 25)
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26. A method for fabricating a lithographic mask comprising:
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providing a transparent substrate with an opaque layer on a first side thereof; forming a first alignment mark in the opaque layer; forming a layer of resist on a second side of the substrate; forming a second alignment mark in the layer of resist by exposing the layer of resist through the first alignment mark and developing the layer of resist a first time; exposing the layer of resist using a mask writer configured to view the second alignment mark; developing the layer of resist a second time to form a resist mask; etching the second side of the substrate using the etch mask to form a diffraction grating comprising a pattern of phase shift grooves etched in a second side of the substrate to a depth selected to diffract and phase shift exposure energy transmitted through the phase shift grooves relative to exposure energy transmitted through adjacent full thickness portions of the substrate; and forming a mask pattern in the opaque layer in alignment with the first alignment mark and at least a portion of the diffraction grating. - View Dependent Claims (27, 28, 29)
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30. A lithographic system for exposing a layer of resist formed on a target, comprising:
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an exposure source for providing an exposure energy; a mask comprising; a transparent substrate having a first side and a second side separated by a thickness; a patterned opaque layer formed on the first side having a primary mask pattern and an alignment mark formed thereon; and a diffraction grating formed on the second side of the mask in alignment with the alignment mark, the diffraction grating comprising a pattern of phase shift grooves etched in the second side of the substrate to a depth selected to diffract and phase shift exposure energy transmitted through the phase shift grooves relative to exposure energy transmitted through adjacent full thickness portions of the substrate to provide off axis illumination for the mask pattern. - View Dependent Claims (31)
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32. A lithographic system comprising:
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an exposure source; and a mask placed between the exposure source and a target, the mask comprising; a substrate having a first side and a second side; a primary mask pattern formed on the first side, the mask pattern comprising a patterned opaque layer with an alignment mark; a diffraction grating formed on the second side in alignment with at least a portion of the primary mask pattern, the diffraction grating comprising a transparent phase layer deposited and patterned with a thickness selected to form phase shifters configured to phase shift and diffract exposure energy directed through the phase shifters relative to exposure energy directed through adjacent portions of the substrate to provide diffracted exposure energy for the primary mask pattern. - View Dependent Claims (33, 34, 35, 36)
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Specification