A method includes inspecting a mask to locate a defect region for a defect of the mask. A phase distribution of an aerial image of the defect region is acquired. A point spread function of an imaging system is determined. One or more repair regions of the mask are identified based on the phase distribution of the aerial image of the defect region and the point spread function. A repair process is performed to the one or more repair regions of the mask to form one or more repair features.

A reflective mask blank includes a substrate, and a multilayer reflective film configured to reflect EUV light, a phase shift film configured to shift a phase of the EUV light, and a semi-light-shielding film configured to shield the EUV light, which are formed on the substrate in this order. A reflectance at a wavelength of 13.5 nm when a surface of the semi-light-shielding film is irradiated with the EUV light is less than 7%. A reflectance at a wavelength of 13.5 nm when a surface of the phase shift film is irradiated with the EUV light is 9% or more and less than 15%.

A reflective mask blank includes a substrate, and a multilayer reflective film configured to reflect EUV light, a phase shift film configured to shift a phase of the EUV light, and a semi-light-shielding film configured to shield the EUV light, which are formed on the substrate in this order. A reflectance at a wavelength of 13.5 nm when a surface of the semi-light-shielding film is irradiated with the EUV light is less than 7%. A reflectance at a wavelength of 13.5 nm when a surface of the phase shift film is irradiated with the EUV light is 9% or more and less than 15%.

A lamella for observation on a transmission electron microscope and other analytical instruments includes multiple thin regions separated by thicker regions or ribs. In some embodiments, the lamella can be wider than 50 μm with more than 10 multiple thin regions, with each thin region may being as thin as 10 nm or even thinner. The process for making such lamellae lends itself to automation. The process is fault tolerant in that not all of the multiple thin regions need to be useable as long as one region provides a useful image. Redeposition is reduced because ion beam imaging is reduced in the automated process and because the ribs reduce redeposition between regions.

A method and apparatus for forming a layer including a light transmitting substrate, and a light shielding film disposed on the light transmitting substrate, and a phase shift film disposed between the light transmitting substrate and the light shielding film. A center measuring area based on the center of the light shielding film and an edge measuring area being distant by 20 mm from the edge of the light shielding film. The center measuring area and the edge measuring area are respectively squares having a side of 20 μm.

A phase shift mask blank includes a transparent substrate, a phase shift layer, a first hard mask layer and an opaque layer. The transparent substrate is disposed on the transparent substrate. The first hard mask layer is disposed on the phase shift layer. The phase shift layer has an etching selectivity with respect to the first hard mask layer. The opaque layer is disposed on the first hard mask layer.

A phase shift mask blank includes a transparent substrate, a phase shift layer, a first hard mask layer and an opaque layer. The transparent substrate is disposed on the transparent substrate. The first hard mask layer is disposed on the phase shift layer. The phase shift layer has an etching selectivity with respect to the first hard mask layer. The opaque layer is disposed on the first hard mask layer.

A laminate for a blank mask includes a light-transmitting layer; a phase shift film disposed on the light-transmitting layer; and residual ions measured from a surface of the phase shift film through ion chromatography comprises at least one of sulfate ions in a concentration of 0 ng/cm.sup.2 to 0.05 ng/cm.sup.2, nitric oxide ions in a concentration of 0 ng/cm.sup.2 to 0.5 ng/cm.sup.2, or ammonium ions in a concentration of 0 ng/cm.sup.2 to 5 ng/cm.sup.2, or any combination thereof. A sum of concentrations of the residual ions is more than 0.

A laminate for a blank mask includes a light-transmitting layer; a phase shift film disposed on the light-transmitting layer; and residual ions measured from a surface of the phase shift film through ion chromatography comprises at least one of sulfate ions in a concentration of 0 ng/cm.sup.2 to 0.05 ng/cm.sup.2, nitric oxide ions in a concentration of 0 ng/cm.sup.2 to 0.5 ng/cm.sup.2, or ammonium ions in a concentration of 0 ng/cm.sup.2 to 5 ng/cm.sup.2, or any combination thereof. A sum of concentrations of the residual ions is more than 0.

The present invention provides a method and apparatus for etching a photomask substrate with enhanced process monitoring, for example, by providing for optical monitoring at certain regions of the photomask to obtain dual endpoints, e.g., etch rate or thickness loss of both a photoresist layer and an absorber layer. By monitoring transmissity of an optical beam transmitted through areas having photoresist layer and etched absorber layer at two different predetermined wavelength, dual process endpoints may be obtained by a signal optical detection.