A method of inspection for defects on a substrate, such as a reflective reticle substrate, and associated apparatuses. The method includes performing the inspection using inspection radiation obtained from a high harmonic generation source and having one or more wavelengths within a wavelength range of between 20 nm and 150 nm. Also, a method including performing a coarse inspection using first inspection radiation having one or more first wavelengths within a first wavelength range; and performing a fine inspection using second inspection radiation having one or more second wavelengths within a second wavelength range, the second wavelength range comprising wavelengths shorter than the first wavelength range.

A method for cleaning a substrate is provided. The method includes following operations. A substrate is received. The substrate has a plurality of conductive nanoparticles disposed over a surface of the substrate. A first mixture is applied to remove the conductive nanoparticles. The first mixture includes an SCl solution, DI water and O.sub.3. A second mixture is applied to the photomask substrate. The second mixture includes DI wafer and H.sub.2. A temperature of the second mixture is between approximately 20° C. and 40° C. The applying of the second mixture further includes a mega sonic agitation, and a frequency of the mega sonic agitation is greater than 3 MHz. A flow rate of the first mixture is between approximately 1000 ml/min and approximately 5000 ml/min. A flow rate of the second mixture is between 1000 ml/min and approximately 3000 ml/min.

A photomask mask assembly includes a reflective photomask and a protection structure. The reflective photomask includes a substrate and a reflective multilayer on a first substrate surface of the substrate at a front side of the reflective photomask. The protection structure is on a second substrate surface of the substrate at a backside of the reflective photomask, and is detachable from the reflective photomask at a temperature below 150 degree Celsius.

A photomask mask assembly includes a reflective photomask and a protection structure. The reflective photomask includes a substrate and a reflective multilayer on a first substrate surface of the substrate at a front side of the reflective photomask. The protection structure is on a second substrate surface of the substrate at a backside of the reflective photomask, and is detachable from the reflective photomask at a temperature below 150 degree Celsius.

Extreme ultraviolet (EUV) mask blanks, methods for their manufacture and production systems therefor are disclosed. The EUV mask blanks comprise a substrate; a multilayer stack of reflective layers on the substrate; a capping layer on the multilayer stack of reflecting layers; an absorber layer on the capping layer, the absorber layer comprising a tantalum-containing material; and a hard mask layer on the absorber layer, the hard mask layer comprising a hard mask material selected from the group consisting of CrO, CrON, TaNi, TaRu and TaCu.

Extreme ultraviolet (EUV) mask blanks, methods for their manufacture and production systems therefor are disclosed. The EUV mask blanks comprise a substrate; a multilayer stack of reflective layers on the substrate; a capping layer on the multilayer stack of reflecting layers; an absorber layer on the capping layer, the absorber layer comprising a tantalum-containing material; and a hard mask layer on the absorber layer, the hard mask layer comprising a hard mask material selected from the group consisting of CrO, CrON, TaNi, TaRu and TaCu.

There are provided a reflective mask having a coating film uniformly formed along the outermost surface and the side surfaces of a transfer pattern, having high EUV transmittance, and having high cleaning resistance and a production method therefor. To achieve the object, for example, a reflective mask (100) includes: a substrate (1); a multilayer reflective film (2) formed on the substrate (1) and reflecting an incident EUV light; an absorption layer (4) formed on at least a part of the multilayer reflective film (2) and absorbing the incident EUV light; and a coating film (5) formed on the multilayer reflective film (2) and on the absorption layer (4) and transmitting the incident EUV light, in which the coating film (5) has an extinction coefficient k of 0.04 or less to the EUV light, is resistant to cleaning with a cleaning chemical solution, and is formed with a uniform film thickness on the surface and the side surfaces of the absorption layer (4).

There are provided a reflective mask having a coating film uniformly formed along the outermost surface and the side surfaces of a transfer pattern, having high EUV transmittance, and having high cleaning resistance and a production method therefor. To achieve the object, for example, a reflective mask (100) includes: a substrate (1); a multilayer reflective film (2) formed on the substrate (1) and reflecting an incident EUV light; an absorption layer (4) formed on at least a part of the multilayer reflective film (2) and absorbing the incident EUV light; and a coating film (5) formed on the multilayer reflective film (2) and on the absorption layer (4) and transmitting the incident EUV light, in which the coating film (5) has an extinction coefficient k of 0.04 or less to the EUV light, is resistant to cleaning with a cleaning chemical solution, and is formed with a uniform film thickness on the surface and the side surfaces of the absorption layer (4).

With respect to a reflective mask blank for a reflective mask used in EUV lithography using EUV light, the reflective mask blank including a substrate, a multilayer reflection film having a periodically laminated structure in which low-refractive index layers composed of a material containing molybdenum and high-refractive index layers are alternately laminated, a protection film, and an absorber film is provided. The low-refractive index layer consists of one or more of first low-refractive index sublayers, and one or more of second low-refractive index sublayers that have a different composition from a composition of the first low-refractive index sublayer.

With respect to a reflective mask blank for a reflective mask used in EUV lithography using EUV light, the reflective mask blank including a substrate, a multilayer reflection film having a periodically laminated structure in which low-refractive index layers composed of a material containing molybdenum and high-refractive index layers are alternately laminated, a protection film, and an absorber film is provided. The low-refractive index layer consists of one or more of first low-refractive index sublayers, and one or more of second low-refractive index sublayers that have a different composition from a composition of the first low-refractive index sublayer.