Reflective optical element for EUV lithography

摘要

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 a first (61) of the at least two materials of the second multilayer system (6) is interrupted by layers (62) having a thickness of up to 1 nm of the at least one further material of the second multilayer system (6) at such distances that the first material is present in an amorphous state.

主权项

1. A reflective optical element operative at a working wavelength in at least one of the soft X-ray and extreme ultraviolet wavelength ranges, comprising:
a first multilayer system comprising at least two alternating materials on a substrate, wherein real parts of refractive indices of the at least two alternating materials differ at the working wavelength, wherein the first multilayer system exerts a layer stress on the substrate, and a second multilayer system comprising at least a first material alternating with a further material on the substrate, wherein the second multilayer system exerts an opposed layer stress on the substrate and is arranged between the first multilayer system and the substrate, wherein the first material of the at least two materials of the second multilayer system is selected from the group consisting of nickel and nickel alloy and is interrupted by a layer of a thickness of up to 1 nm of the further material of the second multilayer system at such distances that the first material is present in the second multilayer system in an amorphous state.