Self-cleaning optic for extreme ultraviolet lithography
AssigneeEuv LLC
InventorsLeonard E. Klebanoff, Richard H. Stulen
Life of this patent
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Abstract
A multilayer reflective optic or mirror for lithographic applications, and particularly extreme ultraviolet (EUV) lithography, having a surface or “capping” layer which in combination with incident radiation and gaseous molecular species such as O2, H2, H2O provides for continuous cleaning of carbon deposits from the optic surface. The metal capping layer is required to be oxidation resistant and capable of transmitting at least 90% of incident EUV radiation. Materials for the capping layer include Ru, Rh, Pd, Ir, Pt and Au and combinations thereof.
Claims18
A self-cleaning reflective optic, comprising:
- a metal disposed on the surface of the optic, wherein said metal protects the optic surface against oxidation and transmits substantially all incident radiation to the underlying optic surface;
- incident radiation;
- and
- least one gaseous reactant, wherein the gaseous reactant is provided at a pressure of at least 10−8 Torr and wherein the gaseous reactant is oxygen, water vapor, air or hydrogen and combinations thereof.
A method for maintaining the surface of a reflective optic designed for use in extreme ultraviolet applications substantially free of carbon contamination, comprising the steps of:
- providing a reflective optic;
- coating the surface of the reflective optic with a metal capping layer, wherein the metal capping layer is protective against oxidation and is capable of transmitting greater than about 90% of incident extreme ultraviolet radiation;
- supplying a reactive gas wherein the reactive gas is oxygen, water vapor, air or hydrogen and combinations thereof, and wherein the pressure of the reactive gas is at least about 10−8 Torr;
- and
- exposing the coated reflective optic and reactive gas to extreme ultraviolet radiation.
Dependencies are inferred from the claim text.