A method of making a mask includes computing a mask volume correction matrix for a given mask layout to be used to perform a lithography process. The mask volume correction matrix represents a diffraction field for a predetermined thickness of a material of the mask. A simulated mask pattern is computed by applying the mask volume correction matrix to the given mask layout. The simulated mask pattern is provided to a mask making tool.

Provided is a reflective mask blank comprising a phase shift film having a small change in the phase difference and/or reflectance of the phase shift film even in a case where the film thickness of the phase shift film changes.

A reflective mask blank comprises a multilayer reflective film and a phase shift film in this order on a main surface of a substrate. The phase shift film comprises a lower layer and an uppermost layer. The lower layer is located between the uppermost layer and the multilayer reflective film. The lower layer is formed of a material in which the total content of ruthenium and chromium is 90 atomic % or more, or a material in which the total content of ruthenium, chromium, and nitrogen is 90 atomic % or more. The uppermost layer is formed of a material in which the total content of ruthenium, chromium, and oxygen is 90 atomic % or more.

Provided is a reflective mask blank comprising a phase shift film having a small change in the phase difference and/or reflectance of the phase shift film even in a case where the film thickness of the phase shift film changes.

A reflective mask blank comprises a multilayer reflective film and a phase shift film in this order on a main surface of a substrate. The phase shift film comprises a lower layer and an uppermost layer. The lower layer is located between the uppermost layer and the multilayer reflective film. The lower layer is formed of a material in which the total content of ruthenium and chromium is 90 atomic % or more, or a material in which the total content of ruthenium, chromium, and nitrogen is 90 atomic % or more. The uppermost layer is formed of a material in which the total content of ruthenium, chromium, and oxygen is 90 atomic % or more.

A lithography mask including a substrate, a phase shift layer on the substrate and an etch stop layer is provided. The phase shift layer is patterned and the substrate is protected from etching by the etch stop layer. The etch stop layer can be a material that is semi-transmissive to light used in photolithography processes or it can be transmissive to light used in photolithography processes.

A lithography mask including a substrate, a phase shift layer on the substrate and an etch stop layer is provided. The phase shift layer is patterned and the substrate is protected from etching by the etch stop layer. The etch stop layer can be a material that is semi-transmissive to light used in photolithography processes or it can be transmissive to light used in photolithography processes.

An extreme ultraviolet lithography (EUVL) method includes providing at least two phase-shifting mask areas having a same pattern. A resist layer is formed over a substrate. An optimum exposure dose of the resist layer is determined, and a latent image is formed on a same area of the resist layer by a multiple exposure process. The multiple exposure process includes a plurality of exposure processes and each of the plurality of exposure processes uses a different phase-shifting mask area from the at least two phase-shifting mask areas having a same pattern.

An extreme ultraviolet lithography (EUVL) method includes providing at least two phase-shifting mask areas having a same pattern. A resist layer is formed over a substrate. An optimum exposure dose of the resist layer is determined, and a latent image is formed on a same area of the resist layer by a multiple exposure process. The multiple exposure process includes a plurality of exposure processes and each of the plurality of exposure processes uses a different phase-shifting mask area from the at least two phase-shifting mask areas having a same pattern.

A phase shift mask suitable for forming a via pattern on a transferred object is provided. The phase shift mask has a first pattern region and a second pattern region. The phase shift mask includes a substrate and a phase shift pattern layer. The phase shift pattern layer is located on the substrate and is disposed corresponding to one of the first pattern region and the second pattern region. An optical phase difference corresponding to the first pattern region and the second pattern region is basically 180 degrees. The first pattern region has a via region away from the second pattern region. The second pattern region includes a plurality of strip patterns surrounding the via region.

A phase shift mask suitable for forming a via pattern on a transferred object is provided. The phase shift mask has a first pattern region and a second pattern region. The phase shift mask includes a substrate and a phase shift pattern layer. The phase shift pattern layer is located on the substrate and is disposed corresponding to one of the first pattern region and the second pattern region. An optical phase difference corresponding to the first pattern region and the second pattern region is basically 180 degrees. The first pattern region has a via region away from the second pattern region. The second pattern region includes a plurality of strip patterns surrounding the via region.

A mask blank including a light shielding film pattern having high ArF light fastness.

The light shielding film is on a transparent substrate. In the mask blank, the light shielding film is a single layer film formed of a material containing silicon and nitrogen, and the light shielding film has an optical density to an ArF excimer laser exposure light of 2.5 or more, a surface reflectance to the exposure light of 40% or less, a back-surface reflectance to the exposure light of 40% or less, a transmittance to a light having a wavelength of 900 nm of 50% or less, an extinction coefficient to a light having a wavelength of 900 nm of 0.04 or more, and a thickness of 60 nm or less.