Method for fabricating and using defect-free phase shifting masks
First Claim
1. A method for forming a phase shift mask comprising:
- providing a transparent substrate;
forming a first layer on the substrate;
forming a phase shift layer on the first layer out of a material that is chemically different than a material of the first layer;
forming a pattern of opaque light blockers on the phase shift layer;
etching the phase shift layer to form a pattern of phase shifters;
depositing a layer of resist on the phase shift layer and exposing and developing the resist to form a mask having openings aligned with the phase shifters; and
etching through the openings in the mask to the first layer to remove a bump defect on the phase shift layer.
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Abstract
A method for forming a defect-free phase shift mask includes forming a mask blank having a substrate, an etch stop layer, a phase shift layer and an opaque layer. The etch stop layer and phase shift layer are formed of chemically different materials to allow selective etching and end point detection. Initially the opaque layer is patterned and etched using a process such as e-beam lithography. Then the phase shift layer is patterned and etched using the etch stop layer as an end point. Bump defects formed in phase shift areas are then removed by exposing a resist layer to leave the phase shifters, or alternately just the defects, unprotected. During defect etching, the etch stop layer can again be used to endpoint the etch process. The etch stop layer can also be formed as a phase shift layer to permit removal of indentation defects using a process such as ion milling.
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Citations
35 Claims
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1. A method for forming a phase shift mask comprising:
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providing a transparent substrate; forming a first layer on the substrate; forming a phase shift layer on the first layer out of a material that is chemically different than a material of the first layer; forming a pattern of opaque light blockers on the phase shift layer; etching the phase shift layer to form a pattern of phase shifters; depositing a layer of resist on the phase shift layer and exposing and developing the resist to form a mask having openings aligned with the phase shifters; and etching through the openings in the mask to the first layer to remove a bump defect on the phase shift layer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method for forming a phase shifting mask comprising:
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providing a transparent substrate; forming an etch stop layer and a phase shift layer on the substrate; depositing, exposing, and developing a first layer of resist to form a first mask for etching the phase shift layer to an endpoint of the etch stop layer to form phase shifters; depositing a second layer of resist over the phase shifters; exposing and developing the second layer of resist to form a second mask with openings aligned with the phase shifters; and removing bump defects on the phase shifters by etching through the openings in the second mask to an endpoint of the etch stop layer. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22)
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23. A method for forming a phase shift mask comprising:
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providing a transparent substrate; forming an etch stop layer on the substrate out of a first material; forming a phase shift layer on the etch stop layer out of a second material that is chemically different than the first material; patterning the opaque layer by exposing and developing a first layer of resist to form a first mask for etching the opaque layer to form opaque light blockers; patterning the phase shift layer by exposing and developing a second layer of resist to form a second mask for etching the opaque layer to the etch stop layer to form phase shifters; removing bump defects on the phase shifters by exposing and developing a third layer of resist using a same pattern as the second mask to form a third mask for etching the bump defects. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30, 31)
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32. A method for forming a phase shift mask comprising:
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providing a transparent substrate; forming an etch stop layer and a phase shift layer on the substrate; forming a pattern of opaque light blockers on the phase shift layer; etching the phase shift layer to the etch stop layer to form a pattern of phase shifters; locating bump defects on the phase shifters; depositing a layer of resist on the phase shift layer; exposing and developing the resist to form a mask having openings aligned with the defects; and etching through the openings in the mask to the etch stop layer to remove the defects. - View Dependent Claims (33, 34, 35)
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Specification