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US 7,022,435 B2Granted
Method for the manufacture of phase shifting masks for EUV lithography
AssigneeEUV Limited Liability Corporation
InventorsDaniel G. Stearns, Donald W. Sweeney, Paul B. Mirkarimi, Anton Barty
Life of this patent
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Abstract
A method for fabricating an EUV phase shift mask is provided that includes a substrate upon which is deposited a thin film multilayer coating that has a complex-valued reflectance. An absorber layer or a buffer layer is attached onto the thin film multilayer, and the thickness of the thin film multilayer coating is altered to introduce a direct modulation in the complex-valued reflectance to produce phase shifting features.
Claims16
A method for fabricating an EUV phase shift mask, comprising:
- providing a substrate;
- depositing a thin film multilayer coating onto said substrate, wherein said thin film multilayer coating comprises a complex-valued reflectance, wherein said thin film multilayer coating comprises alternate molybdenum and silicon layers;
- attaching a layer onto said thin film multilayer, wherein said layer is selected from the group consisting of an absorber layer and a buffer layer;
- and
- changing the thickness of said thin film multilayer coating to introduce a direct modulation in said complex-valued reflectance to produce phase shifting features, wherein the step of changing the thickness is produced by localized heating of a portion of said multilayer thin film coating to a temperature of 800–1000 K for a controlled period of time to activate suicide formation at interfaces between layers of the molybdenum and silicon.
2 more elements
An EUV phase shift mask, comprising:
- a substrate;
- a thin film multilayer coating fixedly attached to said substrate, wherein said thin film multilayer coating comprises a complex-valued reflectance, wherein said thin film multilayer coating comprises alternate molybdenum and silicon layers;
- and
- a layer attached onto said thin film multilayer, wherein said layer is selected from the group consisting of an absorber layer and a buffer layer,
- wherein the thickness of said thin film multilayer coating comprises a variation that introduces a direct modulation in said complex-valued reflectance to produce phase shifting features, wherein said variation is the result of silicide formation at interfaces between layers of the molybdenum and silicon.
2 more elements
Dependencies are inferred from the claim text.