Low-cost method for producing extreme ultraviolet lithography optics
AssigneeThe Regents of the University of California
InventorsJames A. Folta, Claude Montcalm, John S. Taylor, Eberhard A. Spiller
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Abstract
Spherical and non-spherical optical elements produced by standard optical figuring and polishing techniques are extremely expensive. Such surfaces can be cheaply produced by diamond turning; however, the roughness in the diamond turned surface prevent their use for EUV lithography. These ripples are smoothed with a coating of polyimide before applying a 60 period Mo/Si multilayer to reflect a wavelength of 134 Å and have obtained peak reflectivities close to 63%. The savings in cost are about a factor of 100.
Claims15
A method for making an extreme ultraviolet lithography mirror, comprising:
- producing an extreme ultraviolet lithography mirror substrate comprising aluminum;
- depositing a smoothening overcoat layer on said mirror substrate to obtain a required surface smoothness;
- and
- depositing a reflective optical coating onto said smoothening overcoat layer.
An extreme ultraviolet lithography mirror, comprising:
- an extreme ultraviolet lithography mirror substrate comprising aluminum;
- a smoothening overcoat layer on said mirror substrate to obtain a required surface smoothness;
- and
- a reflective optical coating on said smoothening overcoat layer.
Dependencies are inferred from the claim text.