A reflective mask includes a substrate, a reflective multilayer disposed over the substrate, a capping layer disposed over the reflective multilayer, an intermediate layer disposed over the capping layer, an absorber layer disposed over the intermediate layer, and a cover layer disposed over the absorber layer. The intermediate layer includes a material having a lower hydrogen diffusivity than a material of the capping layer.

A reflective mask includes a substrate, a reflective multilayer disposed over the substrate, a capping layer disposed over the reflective multilayer, an intermediate layer disposed over the capping layer, an absorber layer disposed over the intermediate layer, and a cover layer disposed over the absorber layer. The intermediate layer includes a material having a lower hydrogen diffusivity than a material of the capping layer.

A reflective mask blank has a substrate 10; a multilayer reflective film 20 that is provided on the substrate 10 and reflects exposure light; a protective film 50 including a metal oxide film 51 provided on the multilayer reflective film 20; and an absorber film 70 that is provided on the protective film 50 and absorbs exposure light. The multilayer reflective film 20 is configured such that a Mo layer and a Si layer are alternately stacked and a layer on a side farthest from the substrate 10 is the Si layer. The metal oxide film 51 is configured such that an oxygen content in a layer on a side far from the substrate 10 is higher than the oxygen content in a layer on a substrate side.

A reflective mask blank has a substrate 10; a multilayer reflective film 20 that is provided on the substrate 10 and reflects exposure light; a protective film 50 including a metal oxide film 51 provided on the multilayer reflective film 20; and an absorber film 70 that is provided on the protective film 50 and absorbs exposure light. The multilayer reflective film 20 is configured such that a Mo layer and a Si layer are alternately stacked and a layer on a side farthest from the substrate 10 is the Si layer. The metal oxide film 51 is configured such that an oxygen content in a layer on a side far from the substrate 10 is higher than the oxygen content in a layer on a substrate side.

To measure an effect of a wavelength-dependent measuring light reflectivity R.sub.Ret of a lithography mask, a measuring light beam is caused to impinge on said lithography mask within a field of view of a measuring apparatus. The measuring light has a wavelength bandwidth between a wavelength lower limit and a wavelength upper limit differing therefrom. The reflected measuring light emanating from an impinged section of the lithography mask is captured by a detector. A filter with a wavelength-dependent transmission within the wavelength bandwidth is introduced into a beam path of the measuring light beam between the measuring light source and the detector. The measuring light reflected by the lithography mask is captured again by the detector once the filter has been introduced. The wavelength-dependent reflectivity R.sub.Ret or an effect of the wavelength-dependent reflectivity R.sub.Ret is determined on the basis of the capture results. In comparison with the prior art, this yields an improved method for measuring an effect of a measuring light reflectivity on a lithography mask. Additionally, a method for measuring an effect of a polarization of measuring light on a measuring light impingement on a lithography mask is specified, wherein as a result of this the effect of the lithography mask on measuring light is made accessible in respect of further optical parameters of a measurement.

Provided is a substrate with a multilayer reflective film, the substrate being used for manufacturing a reflective mask blank and a reflective mask each having a multilayer reflective film having a high reflectance to exposure light and a low background level during defect inspection.

A substrate with a multilayer reflective film 110 comprises a substrate 1 and a multilayer reflective film 5. The multilayer reflective film 5 is formed of a multilayer film in which a low refractive index layer and a high refractive index layer are alternately layered on the substrate 1. The multilayer reflective film 5 comprises at least one additive element selected from hydrogen (H), deuterium (D), and helium (He). The additive element in the multilayer reflective film 5 has an atomic number density of 0.006 atom/nm.sup.3 or more and 0.50 atom/nm.sup.3 or less.

Provided is a substrate with a multilayer reflective film, the substrate being used for manufacturing a reflective mask blank and a reflective mask each having a multilayer reflective film having a high reflectance to exposure light and a low background level during defect inspection.

A substrate with a multilayer reflective film 110 comprises a substrate 1 and a multilayer reflective film 5. The multilayer reflective film 5 is formed of a multilayer film in which a low refractive index layer and a high refractive index layer are alternately layered on the substrate 1. The multilayer reflective film 5 comprises at least one additive element selected from hydrogen (H), deuterium (D), and helium (He). The additive element in the multilayer reflective film 5 has an atomic number density of 0.006 atom/nm.sup.3 or more and 0.50 atom/nm.sup.3 or less.

A reflective mask cleaning apparatus according to an embodiment comprises a first supply section configured to supply a first solution containing at least one of an organic solvent and a surfactant to a ruthenium-containing capping layer provided in a reflective mask; and a second supply section configured to supply at least one of a reducing solution and an oxygen-free solution to the capping layer. A reflective mask cleaning apparatus according to an alternative embodiment comprises a third supply section configured to supply a plasma product produced from a reducing gas to a ruthenium-containing capping layer provided in a reflective mask; and a second supply section configured to supply at least one of a reducing solution and an oxygen-free solution to the capping layer.

A reflective mask cleaning apparatus according to an embodiment comprises a first supply section configured to supply a first solution containing at least one of an organic solvent and a surfactant to a ruthenium-containing capping layer provided in a reflective mask; and a second supply section configured to supply at least one of a reducing solution and an oxygen-free solution to the capping layer. A reflective mask cleaning apparatus according to an alternative embodiment comprises a third supply section configured to supply a plasma product produced from a reducing gas to a ruthenium-containing capping layer provided in a reflective mask; and a second supply section configured to supply at least one of a reducing solution and an oxygen-free solution to the capping layer.

An extreme ultraviolet mask including a substrate, a reflective multilayer stack on the substrate and a capping layer on the reflective multilayer stack is provided. The reflective multilayer stack is treated prior to formation of the capping layer on the reflective multilayer stack. The capping layer is formed by an ion-assisted ion beam deposition or an ion-assisted sputtering process.