Invention Grant
US08928972B2 Reflective optical element for EUV lithography 有权
用于EUV光刻的反光光学元件

Reflective optical element for EUV lithography
Abstract:
A stress-reduced reflective optical element for a working wavelength in the soft X-ray and extreme ultraviolet wavelength range includes a first multilayer system (4) of at least two alternating materials (41, 42) having different real parts of the refractive index at the working wavelength on a substrate (2), which exerts a layer stress on the substrate (2), and comprising a second multilayer system (6) of at least two alternating materials (61, 62) on a substrate (2), which exerts an opposed layer stress on the substrate (2) and is arranged between the first multilayer system (4) and the substrate (2), wherein one of the materials (61) of the second multilayer system (6) is nickel-vanadium-silicon, and wherein the ratio (G) of the overall thickness of nickel-vanadium-silicon layers (61) within one period (60) of the second multilayer system (6) to the overall thickness of the period (60) of the second multilayer system (6) is at least 0.25.
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