Reflective mask blank and reflective mask

Abstract

A reflective mask blank (100) includes a substrate 1, a multilayer reflective film 2 provided on one main surface of the substrate 1 and configured to reflect exposure light, and an absorber film 5 provided on the multilayer reflective film 2. The absorber film 5 contains one or both of ruthenium (Ru) and platinum (Pt), and contains one or both of carbon (C) and silicon (Si). A two times average square root roughness (Sq) of a surface of the absorber film 5 is 0.40 nm or less.

Description

Technical Field

[0001] The present invention relates to reflective mask blanks as raw materials for reflective masks used in the manufacture of semiconductor devices such as LSIs, and to reflective masks manufactured from reflective mask blanks. Background Technology

[0002] In the manufacturing process of semiconductor devices, photolithography is a technique that repeatedly exposes a transfer mask with light to transfer the circuit pattern formed on the mask onto the semiconductor substrate (semiconductor wafer) using a shrinking projection optical system. Previously, the wavelength of the exposure light was mainly 193nm using an argon fluoride (ArF) excimer laser. Through multiple patterning processes using combined exposure techniques or other processing methods, patterns smaller than the exposure wavelength are ultimately formed.

[0003] However, due to the continuous miniaturization of device patterns, further finer patterns are needed. Therefore, extreme ultraviolet (EUV) light, with a wavelength shorter than ArF excimer laser, has gradually been used as the exposure light, leading to the adoption of EUV lithography. EUV light refers to light with a wavelength of approximately 0.2–100 nm, more specifically, light with a wavelength around 13.5 nm. EUV light has extremely low transmittance to materials, making conventional transmissive projection optical systems and masks unsuitable. Therefore, reflective optical elements are used. Consequently, reflective masks are also used for pattern transfer.

[0004] A reflective mask is formed by forming a multilayer reflective film that reflects EUV light on a substrate, and then forming an absorber film pattern that absorbs EUV light on the multilayer reflective film. On the other hand, the absorber film in its state before patterning (including the absorber film in the state where a resist film has been formed) is called a reflective mask blank, which is used as the material for the reflective mask. A reflective mask blank generally has a basic structure including a substrate with low thermal expansion, a multilayer reflective film that reflects EUV light formed on one of the two main surfaces of the substrate, and an absorber film that absorbs EUV light formed thereon.

[0005] As a multilayer reflective film, a multilayer reflective film that achieves the necessary reflectivity for EUV light by alternately stacking molybdenum (Mo) layers and silicon (Si) layers is generally used. On the other hand, as an absorber film, tantalum (Ta) and the like, which have a relatively large extinction coefficient for EUV light, are used (Japanese Patent Application Laid-Open No. 2002-246299).

[0006] Furthermore, as a protective film (capping layer) used to protect the multilayer reflective film during processes such as cleaning reflective masks, as disclosed in Japanese Patent Publication No. 2002-122981 and Japanese Patent Publication No. 2005-516182, a ruthenium (Ru) film or a rhodium (Rh) film is formed on top of the multilayer reflective film. Additionally, when patterning the absorption film, a hard mask film containing chromium (Cr) is sometimes formed on top of the absorption film as an etching mask. On the other hand, a conductive film is formed on another main surface of the substrate. As a conductive film, metal nitride films have been proposed for achieving electrostatic chucking, mainly including films containing chromium (Cr) and tantalum (Ta).

[0007] In EUV lithography, EUV light, used as the exposure light, is incident on a reflective mask at an angle, typically set to 6 degrees relative to the normal of the mask's main surface. A portion of this angled exposure light is blocked by the sidewalls of the absorber pattern, creating a so-called 3D effect (three-dimensional effect, shadow effect). This 3D effect is the cause of positional or dimensional deviations in the transferred pattern; therefore, minimizing the 3D effect is crucial during pattern minimization. Since a thinner absorber pattern results in a smaller 3D effect, achieving thin-film absorption of the absorber pattern is desirable.

[0008] Ruthenium (Ru) is a material with a lower refractive index and a smaller extinction coefficient relative to EUV light. Using Ruthenium (Ru) to create reflective masks for circuit patterns allows for a phase shift effect—a phase shift of approximately 150° to 250° in the reflected light—achieving higher contrast even with thinner films, thus reducing 3D effects. Furthermore, platinum (Pt), a material with a similar refractive index to Ruthenium (Ru) and a higher extinction coefficient than tantalum (Ta), can also reduce 3D effects by imparting a phase shift effect.

[0009] Absorber films composed of ruthenium (Ru) or platinum (Pt) are prone to crystallization during film formation, and the resulting grain growth leads to increased surface roughness. Reflective mask blanks with absorber films exhibiting increased surface roughness are susceptible to false defects during defect detection using visible light, ultraviolet light, or EUV light. To distinguish between false defects caused by surface roughness and actual defects affecting pattern transfer, an additional discrimination step is required, increasing detection time. Alternatively, reducing detection sensitivity to avoid false defects caused by surface roughness may fail to detect actual defects affecting pattern transfer.

[0010] Therefore, the smaller the surface roughness of the absorber membrane, the better.

[0011] In order to solve the above-mentioned problems, the inventors conducted in-depth research and found that by further adding one or two of carbon (C) and silicon (Si) to an absorber membrane containing one or two of ruthenium (Ru) and platinum (Pt), the surface roughness of the absorber membrane can be reduced, thus completing the present invention. Summary of the Invention

[0012] The present invention provides the following embodiments

[0013] [Concept 1]

[0014] The reflective mask blank provided by this invention includes:

[0015] substrate;

[0016] A multilayer reflective film disposed on a main surface of the substrate for reflecting exposure light; and

[0017] An absorber film disposed above the multilayer reflective film;

[0018] The absorber film contains one or both of ruthenium (Ru) and platinum (Pt), and one or both of carbon (C) and silicon (Si), and the square root average roughness (Sq) of the absorber film surface is below 0.40 nm.

[0019] [Concept 2]

[0020] In the reflective mask blank described in Concept 1

[0021] In the X-ray diffraction pattern of the absorber film obtained by out-of-plane measurement using CuKα rays, the half-width of the strongest diffraction peak observed between 30° and 50° can be greater than 0.60°.

[0022] [Concept 3]

[0023] In the reflective mask blank described in Concept 1 or 2

[0024] The absolute value of the membrane stress of the absorber membrane can be below 2000 MPa.

[0025] [Concept 4]

[0026] In any one of Concepts 1 to 3, the reflective mask blank

[0027] The absorber membrane may contain carbon (C), and its content is between 4 atomic% and 40 atomic%.

[0028] [Concept 5]

[0029] In any of the reflective mask blanks described in Concepts 1 to 4

[0030] The absorber membrane may contain silicon (Si) in a content of more than 4 atomic% and less than 40 atomic%.

[0031] [Concept 6]

[0032] The reflective mask blank according to any one of concepts 1 to 5 may further include:

[0033] A protective film is disposed between the multilayer reflective film and the absorber film, the protective film comprising one or both of ruthenium (Ru) and rhodium (Rh).

[0034] [Concept 7]

[0035] The reflective mask blank according to any one of concepts 1 to 6 may further include:

[0036] An etching barrier film is disposed between the multilayer reflective film and the absorber film, the etching barrier film comprising at least one selected from niobium (Nb), tantalum (Ta), silicon (Si) and chromium (Cr).

[0037] [Concept 8]

[0038] The reflective mask blank according to any one of concepts 1 to 7 may further include:

[0039] A hard mask film disposed above the absorber film, the hard mask film comprising at least one selected from niobium (Nb), tantalum (Ta), silicon (Si) and chromium (Cr).

[0040] [Concept 9]

[0041] The reflective mask provided by this invention can have:

[0042] The absorber pattern formed by patterning the absorber film of any one of Concepts 1 to 8.

[0043] Invention Effects

[0044] According to the present invention, it is possible to reduce surface roughness. Attached Figure Description

[0045] Figure 1 This is a cross-sectional view of an example of a reflective mask blank according to an embodiment of the present invention.

[0046] Figure 2 This is a cross-sectional view of an example of a reflective mask blank containing a hard mask film according to an embodiment of the present invention.

[0047] Figure 3 This is a cross-sectional view of an example of a reflective mask according to an embodiment of the present invention.

[0048] Figure 4 This is a cross-sectional view of an example of a reflective mask blank containing a hard mask film and a resist film according to an embodiment of the present invention. Detailed Implementation

[0049] The specific embodiments of the present invention will be described in more detail below.

[0050] like Figure 1 As shown, the reflective mask blank 100 of this embodiment includes a substrate 1, a multilayer reflective film 2 formed on the substrate 1 (on one main surface (front) of the substrate 1) for reflecting exposure light, and an absorber film 5 formed above the multilayer reflective film 2. The reflective mask blank 100 of this embodiment is suitable as... Figure 3 The image shows the raw material (EUV mask blank) for the reflective mask 110 (EUV mask) used in EUV lithography, which uses EUV light as the exposure light. In EUV lithography, the EUV light used has a wavelength of 13-14 nm, typically about 13.5 nm.

[0051] The substrate 1 used for EUV light exposure preferably has low thermal expansion characteristics; for example, it is preferably made of material with a coefficient of thermal expansion of ±2×10⁻⁻⁻⁶. 8 Within / ℃ (more preferably ±5×10⁻) 9 The substrate 1 is formed from materials within a temperature range of ℃. Examples of such materials include titanium dioxide-doped quartz glass (SiO2-TiO2-based glass). Furthermore, the substrate 1 preferably uses a material with a sufficiently planarized surface, and the surface roughness of the main surface of the substrate 1, in terms of RMS value, is preferably 0.2 nm or less, more preferably 0.15 nm or less. This surface roughness can be obtained through processes such as grinding the substrate 1. Further, the substrate 1 preferably has a flatness of 100 nm or less. Regarding the dimensions of the substrate 1, it is preferable that the main surface area of ​​the substrate 1 is 152 mm square and the thickness of the substrate 1 is 6.35 mm. A substrate 1 of this size is referred to as a 6025 substrate (a substrate with a main surface area of ​​6 inches square and a thickness of 0.25 inches).

[0052] The multilayer reflective film 2 is a film used to reflect exposure light in the reflective mask 110. The multilayer reflective film 2 is preferably disposed in direct contact with one main surface of the substrate 1, but other films such as a base film can also be disposed between one main surface of the substrate 1 and the multilayer reflective film 2. Figure 4 As shown, the multilayer reflective film 2 has a periodic stacked structure, which is composed of alternating layers of a high refractive index layer 21 with a relatively high refractive index to the exposure light and a low refractive index layer 22 with a relatively low refractive index to the exposure light. It should be noted that, although not explicitly shown in the figure, Figures 1 to 3The multilayer reflective film 2 shown also has a periodic stacked structure consisting of alternating layers of high refractive index layer 21 and low refractive index layer 22.

[0053] The high refractive index layer 21 is preferably formed of a material containing silicon (Si). The high refractive index layer 21 may contain one or more additive elements selected from oxygen (O), nitrogen (N), carbon (C), boron (B), and hydrogen (H), and may also be formed of a multilayer structure consisting of layers containing additive elements and layers without additive elements. The thickness of the high refractive index layer 21 is preferably 3.5 nm or more (more preferably 4 nm or more), and preferably 4.9 nm or less (more preferably 4.4 nm or less).

[0054] The low-refractive-index layer 22 is preferably formed of a material containing molybdenum (Mo), but may also be formed of a material containing ruthenium (Ru). The low-refractive-index layer 22 may also employ a multilayer structure of Mo and Ru. The low-refractive-index layer 22 may contain one or more additive elements selected from oxygen (O), nitrogen (N), carbon (C), boron (B), and hydrogen (H), and may also be formed of a multilayer structure consisting of layers containing additive elements and layers without additive elements. The thickness of the low-refractive-index layer 22 is preferably 2.1 nm or more (more preferably 2.6 nm or more), and preferably 3.5 nm or less (more preferably 3 nm or less).

[0055] The periodic stacked structure only needs to include a high-refractive-index layer 21 and a low-refractive-index layer 22, and one or more high-refractive-index layers 21 and low-refractive-index layers 22 are required within one cycle. The periodic stacked structure contains at least two layers, for example, it can be composed of one high-refractive-index layer 21 and one low-refractive-index layer 22. In addition, it can also contain two or more high-refractive-index layers 21 with different compositions (e.g., different composition ratios, different compositions due to the presence or absence of added elements, etc.), or it can contain two or more low-refractive-index layers 22 with different compositions (e.g., different composition ratios, different compositions due to the presence or absence of added elements, etc.). In this case, the periodic stacked structure contains at least three layers, and can also contain four or more or five or more layers, but preferably eight or fewer layers. The number of repetitions of the cycle is preferably 20 or more, and preferably 50 or fewer (more preferably 40 or fewer).

[0056] The thickness of the multilayer reflective film 2 with a periodic stacked structure can be adjusted according to the exposure wavelength and the incident angle of the exposure light, preferably 130nm or more and 400nm or less, more preferably 290nm or less.

[0057] The formation of the multilayer reflective film 2 can be achieved through sputtering methods, such as supplying power to the target material, using the supplied power to plasmaize (ionize) the atmospheric gas, and then sputtering it; or ion beam sputtering, where an ion beam is irradiated onto the target material. Sputtering methods include DC sputtering, where a DC voltage is applied to the target material, and RF sputtering, where a high-frequency voltage is applied to the target material. Sputtering refers to applying a voltage to the target material while sputtering gas is introduced into the chamber, ionizing the gas, and forming a film using the sputtering phenomenon of gas ions. Magnetron sputtering has advantages in production efficiency. The power applied to the target material can be DC or high-frequency. Furthermore, DC sputtering also includes pulse sputtering, where the negative bias voltage applied to the target material is briefly reversed to prevent charge accumulation.

[0058] The multilayer reflective film 2 can be formed, for example, by sputtering using a sputtering apparatus capable of mounting multiple targets. Specifically, as the target, a molybdenum (Mo) target for forming a molybdenum (Mo) layer, a ruthenium (Ru) target for forming a ruthenium (Ru) layer, or a silicon (Si) target for forming a silicon (Si) layer can be appropriately selected, and rare gases such as neon (Ne), argon (Ar), krypton (Kr), and xenon (Xe) are used as sputtering gases for film formation.

[0059] In addition, reactive sputtering can also be used, employing reactive gases. For example, when forming a nitrogen (N) film, nitrogen-containing gases such as nitrogen (N2) can be used; when forming an oxygen (O) film, oxygen-containing gases such as oxygen (O2) can be used; when forming a film containing both nitrogen (N) and oxygen (O), nitrogen oxide gases such as nitrous oxide (N2O), nitric oxide (NO), and nitrogen dioxide (NO2) can be used; when forming a film containing carbon (C) and oxygen (O), carbon oxide gases such as carbon monoxide (CO) and carbon dioxide (CO2) can be used; when forming a hydrogen (H) film, hydrogen-containing gases such as hydrogen (H2) can be used; and when forming a film containing both carbon (C) and hydrogen (H), hydrocarbon gases such as methane (CH4) can be used together with rare gases.

[0060] In addition, when forming a boron (B)-containing layer, a molybdenum (Mo) target with added boron (B) (molybdenum boride (MoB) target) or a silicon (Si) target with added boron (B) (silicon boride (SiB) target) can be used.

[0061] like Figure 1 , Figure 2 and Figure 4 As shown, a protective film 3, also known as a cover film, can be disposed above the multilayer reflective film 2. The protective film 3 is a film used to protect the multilayer reflective film 2 and is usually disposed in direct contact with the multilayer reflective film 2. The protective film 3 is preferably formed of a material containing ruthenium (Ru) or rhodium (Rh).

[0062] The ruthenium (Ru)-containing material used in the protective film 3 can include elemental ruthenium (Ru) and alloys composed of ruthenium (Ru) and metals or semi-metals other than ruthenium (Ru). Examples of metals or semi-metals other than ruthenium (Ru) include rhodium (Rh), niobium (Nb), rhenium (Re), zirconium (Zr), titanium (Ti), chromium (Cr), and silicon (Si). Among these, elemental ruthenium (Ru) is particularly preferred, and the protective film 3 is preferably formed of ruthenium (Ru). The content of metals or semi-metals other than ruthenium (calculated on an overall average basis) in the protective film 3 is preferably 50 atomic% or less, more preferably 30 atomic% or less. While there is no particular limitation on the lower limit of the content of this metal or semi-metal, it is preferably 5 atomic% or more, more preferably 10 atomic% or more.

[0063] The rhodium (Rh)-containing material used in the protective film 3 can include elemental rhodium (Rh) and alloys composed of rhodium (Rh) and metals or semi-metals other than rhodium (Rh). Examples of metals or semi-metals other than rhodium (Rh) include ruthenium (Ru), niobium (Nb), rhenium (Re), zirconium (Zr), titanium (Ti), chromium (Cr), and silicon (Si). Among these, elemental rhodium (Rh) is particularly preferred, and the protective film 3 is preferably formed of rhodium (Rh). The content of metals or semi-metals other than rhodium (Rh) in the protective film 3 (calculated on an overall average basis) is preferably 50 atomic% or less, more preferably 30 atomic% or less. While there is no particular limitation on the lower limit of the content of this metal or semi-metal, it is preferably 5 atomic% or more, more preferably 10 atomic% or more.

[0064] The protective film 3 can be a single-layer structure or a multi-layer structure composed of multiple layers with different compositions; in addition, each layer constituting the single layer or multiple layers can also have a gradient composition structure with continuously varying composition in the thickness direction.

[0065] The thickness of the protective film 3 is preferably 1 nm or more (more preferably 2 nm or more), and preferably 5 nm or less (more preferably 4 nm or less).

[0066] The protective film 3 is formed by: appropriately selecting ruthenium (Ru) targets, rhodium (Rh) targets, or metal or semi-metal targets different from the above (specifically niobium (Nb) targets, rhenium (Re) targets, zirconium (Zr) targets, titanium (Ti) targets, chromium (Cr) targets, silicon (Si) targets, or targets composed of two or more of ruthenium (Ru), niobium (Nb), rhenium (Re), zirconium (Zr), titanium (Ti), chromium (Cr), and silicon (Si), etc.), and using rare gases such as neon (Ne), argon (Ar), krypton (Kr), and xenon (Xe) as sputtering gases, and forming the film by sputtering. The preferred sputtering method is magnetron sputtering.

[0067] In this embodiment, such as Figure 1 , Figure 2 and Figure 4 As shown, an absorber film 5 is disposed above the multilayer reflective film 2. The absorber film 5 is a film that absorbs exposure light (specifically EUV light) and reduces reflectivity; in addition, the absorber film 5 can also serve as a phase shifting film, which has a phase shifting function of absorbing part of the exposure light and reflecting part of the exposure light in the form of reflected light with a phase change of about 150 to 250°. Other films (such as the protective film 3 mentioned above or the etching barrier film 4 described later) can be disposed between the absorber film 5 and the multilayer reflective film 2. It should be noted that even without the protective film 3 or the etching barrier film 4, the absorber film 5 can be formed directly on the multilayer reflective film 2 (in contact).

[0068] The absorber film 5 of this embodiment contains one or both of ruthenium (Ru) and platinum (Pt), and also one or both of carbon (C) and silicon (Si). By including one or both of carbon (C) and silicon (Si), the crystallinity of the absorber film 5 containing one or both of ruthenium (Ru) and platinum (Pt) can be changed, reducing coarse crystalline particles. Therefore, the surface roughness of the absorber film 5 can be reduced. The square root mean roughness (Sq) of the surface of the absorber film 5 of this embodiment is 0.40 nm or less.

[0069] The carbon (C) content in the absorber film 5 can be from 4 atomic% to 40 atomic%; the silicon (Si) content can also be from 4 atomic% to 40 atomic%. By including carbon (C) or silicon (Si) within the above range, the crystallinity of the absorber film 5 can be changed, thereby reducing its surface roughness. If the content of carbon (C) or silicon (Si) is too low, the effect of reducing surface roughness cannot be obtained; conversely, if the content is too high, the transfer performance may decrease due to the change in the refractive index of the absorber film 5 to the exposed light. The absorber film 5 preferably has a microcrystalline or amorphous structure, wherein the grain size of ruthenium (Ru) or platinum (Pt) is preferably less than 15 nm, more preferably less than 10 nm, and even more preferably less than 5 nm. By adopting such a grain size, the surface roughness of the absorber film 5 can be effectively reduced.

[0070] Grain size (grain diameter) can be determined by X-ray diffraction and obtained using the following Scherrer formula:

[0071] Grain size (nm) = Kλ / (βcosθ)

[0072] (In the formula, K is the Scherrer constant (taken as 0.95 here), λ is the wavelength of the X-ray used for measurement (0.154nm), β is the full width at half maximum (FWHM) of the diffraction peak (in radians), and θ is the Bragg angle of the diffraction peak (taken as the midpoint of FWHM here).

[0073] Half-width at half-maximum (HWHM) refers to the width of the diffraction peak at the height corresponding to the average of the background intensity and the maximum peak intensity when the diffraction peak is plotted with the diffraction angle 2θ as the horizontal axis and the diffraction intensity as the vertical axis. The unit is the same as the diffraction angle 2θ.

[0074] To obtain the aforementioned preferred grain size, in the X-ray diffraction pattern of the absorber film 5 obtained using out-of-plane measurement with CuKα rays, the full width at half maximum (FWHM) of the strongest diffraction peak originating from ruthenium (Ru) or platinum (Pt) observed at a diffraction angle 2θ between 30° and 50° is preferably 0.60° or more, more preferably 0.90° or more, and even more preferably 1.6° or more. It should be noted that if no diffraction peak appears in this region, the absorber film 5 is an amorphous structure, and in this case, the FWHM of the diffraction peak is defined as 180°.

[0075] like Figure 3 As shown, when patterning the absorber film 5 of the reflective mask blank 100 to fabricate the reflective mask 110, if the film stress of the absorber film 5 is large, the warpage of the substrate 1 before and after pattern formation will change, which may lead to problems such as pattern position shift. Therefore, the lower the film stress of the absorber film 5, the better. Its absolute value is preferably 2000 MPa or less, more preferably 1500 MPa or less, and even more preferably 1000 MPa or less. A preferred film stress can also be obtained by controlling the content of carbon (C) or silicon (Si) in the absorber film 5 within the above range. Specifically, a preferred film stress can be obtained by setting the carbon (C) content in the absorber film 5 to 4 atomic% or more and 40 atomic% or less, or the silicon (Si) content to 4 atomic% or more and 40 atomic% or less. Figure 3 In the diagram, symbol 41 represents the pattern of the etch barrier film 4 (etch barrier pattern), and symbol 51 represents the pattern of the absorber film 5 (absorber pattern).

[0076] From the perspective of making the membrane stress, grain size, etc. more within the preferred range, when the absorber membrane 5 does not contain platinum (Pt) but contains ruthenium (Ru) and carbon (C) (typically the absorber membrane 5 is composed of RuC), the carbon (C) content is more preferably 10 atomic% or more.

[0077] When the absorber membrane 5 contains ruthenium (Ru) and silicon (Si), the content of silicon (Si) is more preferably 20 atomic% or more.

[0078] When the absorber film 5 does not contain ruthenium (Ru) but contains platinum (Pt) and silicon (Si) (typically, the absorber film 5 is composed of PtSi), it is more preferable to set the absolute value of the film stress to be smaller by setting the silicon (Si) content to 8 atomic% or more; from the perspective of making the grain size more within the preferred range, the silicon (Si) content is preferably set to 20 atomic% or more.

[0079] Besides carbon (C) and silicon (Si), the surface roughness can also be reduced by including light elements such as nitrogen (N) and oxygen (O) in the absorber film 5. However, noble metals such as ruthenium (Ru) and platinum (Pt) do not easily form compounds with oxygen (O) and nitrogen (N), and even if they do, they are easily decomposed under the influence of energy such as heat, which may cause changes in the transfer performance of the reflective mask 110. Therefore, the absorber film 5 is preferably free of oxygen (O) and nitrogen (N).

[0080] When forming a carbon (C) layer, in addition to using carbon (C) targets and other targets (such as ruthenium (Ru) targets, platinum (Pt) targets, etc.) simultaneously for film formation, it can also be formed by reactive sputtering using carbon oxide gases such as carbon monoxide (CO) gas and carbon dioxide (CO2) gas, or hydrocarbon gases such as methane (CH4) gas, together with rare gases. Furthermore, carbon (C)-added ruthenium (Ru) targets (ruthenium carbide (RuC) targets) and carbon (C)-added platinum (Pt) targets (platinum carbide (PtC) targets) can also be used to form carbon (C)-containing layers.

[0081] When forming a silicon (Si) layer, in addition to using silicon (Si) targets and other targets (such as ruthenium (Ru) targets, platinum (Pt) targets, etc.) can be used simultaneously for film formation. Alternatively, ruthenium (Ru) targets with added silicon (Si) (ruthenium silicide (RuSi) targets) and platinum (Pt) targets with added silicon (Si) (platinum silicide (PtSi) targets) can be used to form the layer.

[0082] The thickness of the absorber film 5 may vary depending on factors such as the light source and pattern spacing during exposure, and is not particularly limited, but is preferably 20 nm or more (more preferably 30 nm or more), and preferably 60 nm or less (more preferably 50 nm or less).

[0083] An etching barrier film 4 with different etching characteristics than the absorber film 5 may be disposed between the protective film 3 and the absorber film 5. This etching barrier film 4 can be removed from the opening of the absorber pattern 51 after the absorber pattern 51 is formed, becoming part of the pattern (see...). Figure 3 Alternatively, it can remain on the multilayer reflective film 2 without being removed from the opening of the absorber pattern 51. In either case, it is preferable to choose a material and film thickness that will not adversely affect the transfer performance.

[0084] When patterning the absorber film 5 using a fluorine (F)-containing gas via dry etching, an etching barrier film 4 containing chromium (Cr) can be used. Furthermore, when patterning the absorber film 5 using a gas containing chlorine (Cl) and oxygen (O) via dry etching, an etching barrier film 4 containing at least one of niobium (Nb), tantalum (Ta), and silicon (Si) can be used. The etching barrier film 4 may further contain elements such as oxygen (O), nitrogen (N), carbon (C), and boron (B).

[0085] The etching barrier film 4 can be formed by sputtering. Specifically, it can be formed using metal or semi-metal targets such as chromium (Cr), niobium (Nb), tantalum (Ta), and silicon (Si), or compound targets such as chromium compound targets, niobium compound targets, tantalum compound targets, and silicon compound targets (i.e., targets containing metals or semi-metals such as Cr, Nb, Ta, and Si, along with other metal / semi-metal elements, or light elements such as oxygen (O), nitrogen (N), carbon (C), and boron (B)). Sputtering can be performed using rare gases such as neon (Ne), argon (Ar), krypton (Kr), and xenon (Xe). Alternatively, it can be formed by reactive sputtering using rare gases with reactive gases such as oxygen-containing gases, nitrogen-containing gases, and carbon-containing gases. The thickness of the etching barrier film 4 is not particularly limited, but is typically about 2–10 nm.

[0086] like Figure 2 As shown, on the side of the absorber film 5 away from the substrate 1, a hard mask film 6 (an etching mask film of the absorber film 5) with different etching characteristics than the absorber film 5 is preferably disposed in contact with the absorber film 5. This hard mask film 6 functions as an etching mask during dry etching of the absorber film 5. After the absorber pattern 51 is formed, the hard mask film 6 can be retained on the reflective mask 110 as a reflectivity reduction layer to reduce reflectivity at the wavelength of light used in inspections such as pattern detection, or it can be removed and not retained on the reflective mask 110.

[0087] There is no particular limitation on the thickness of the hard mask film 6, but if it is too thin, it may not be able to perform the function of the hard mask, and if it is too thick, it may lead to deterioration of the processing characteristics. Therefore, it is preferred to be 1 nm or more (more preferably 2 nm or more, and even more preferably 5 nm or more), and preferably 20 nm or less (more preferably 10 nm or less).

[0088] When patterning the absorber film 5 using a fluorine (F)-containing gas via dry etching, a hard mask film 6 containing chromium (Cr) can be used. Furthermore, when patterning the absorber film 5 using a gas containing chlorine (Cl) and oxygen (O) via dry etching, a hard mask film 6 containing at least one of niobium (Nb), tantalum (Ta), and silicon (Si) can be used. The hard mask film 6 may further contain elements such as oxygen (O), nitrogen (N), carbon (C), and boron (B).

[0089] The hard mask film 6 can be formed by sputtering. Specifically, it can use metal or semi-metal targets such as chromium (Cr), niobium (Nb), tantalum (Ta), and silicon (Si), or compound targets such as chromium compound targets, niobium compound targets, tantalum compound targets, and silicon compound targets (i.e., targets containing metals or semi-metals such as Cr, Nb, Ta, and Si, and other metal / semi-metal elements, or light elements such as oxygen (O), nitrogen (N), carbon (C), and boron (B)). Sputtering can be performed using rare gases such as neon (Ne), argon (Ar), krypton (Kr), and xenon (Xe). Alternatively, it can be formed by reactive sputtering using rare gases with reactive gases such as oxygen-containing gases, nitrogen-containing gases, and carbon-containing gases. The thickness of the hard mask film 6 is not particularly limited, but it is typically about 2–10 nm.

[0090] like Figures 1 to 4 As shown, a conductive film 50 is preferably disposed on the opposite side of one main surface of the substrate 1 (i.e., the other main surface, the back surface), in contact with the other main surface. This conductive film is used for electrostatic chuck adsorption of the reflective mask 110 in an exposure apparatus (e.g., an EUV scanner).

[0091] The sheet resistance of the conductive film 50 is preferably below 100 Ω / □, and the material is not particularly limited. Materials containing tantalum (Ta) or chromium (Cr) can be used as materials for the conductive film 50. Materials containing tantalum (Ta) may contain elements such as oxygen (O), nitrogen (N), carbon (C), and boron (B); materials containing chromium (Cr) may contain elements such as oxygen (O), nitrogen (N), and carbon (C). Specific tantalum (Ta) materials used in forming the conductive film 50 include: elemental Ta, TaO, TaN, TaON, TaC, TaCN, TaCO, TaCON, TaB, TaOB, TaNB, TaONB, TaCB, TaCNB, TaCOB, and TaCONB, etc. Specific chromium (Cr) materials used in forming the conductive film 50 include: elemental Cr, CrO, CrN, CrON, CrC, CrCN, CrCO, and CrCON, etc.

[0092] The thickness of the conductive film 50 only needs to meet the functional requirements of the electrostatic chuck and is not particularly limited, but is typically about 20–300 nm. Preferably, the thickness of the conductive film 50 is balanced with the film stress of the film and film pattern formed on a main surface (front side) after the formation of the reflective mask 110 (i.e., the formation of the pattern of the absorber film 5). The conductive film 50 can be formed before the formation of the multilayer reflective film 2, or after the formation of all films on the multilayer reflective film 2 side (front side) of the substrate 1; alternatively, the conductive film 50 can be formed first after the formation of a portion of the films on the multilayer reflective film 2 side of the substrate 1, and then the remaining portion of the film can be formed. The conductive film 50 can be formed, for example, by magnetron sputtering.

[0093] The reflective mask blank 100 may further form a resist film 9 on the side furthest from the substrate 1 (see...). Figure 4 In this embodiment, the resist film 9 is preferably an electron beam (EB) resist. Furthermore, the resist film 9 is preferably removed by SPM cleaning. Figure 4 In the embodiment shown, the resist film 9 is disposed in contact with the upper surface of the hard mask film 6, and the hard mask film 6 is disposed in contact with the upper surface of the absorber film 5.

[0094]

Example

[0095] The present invention is illustrated below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0096] [Example 1]

[0097] As substrate 1, a low thermal expansion glass substrate (SiO2-TiO2 based glass substrate) with a diameter of 152 mm and a thickness of 6.35 mm is used. The Young's modulus of substrate 1 is 67.6 GPa, the Poisson's ratio is 0.17, and the flatness of the central 142 mm square area of ​​the main surface of substrate 1 is less than 100 nm.

[0098] The method for forming the multilayer reflective film 2 is as follows: The substrate 1 is placed in a sputtering cavity containing a silicon (Si) target and a molybdenum (Mo) target, and the multilayer reflective film 2 is formed on a main surface of the substrate 1 by DC magnetron sputtering. Specifically, firstly, argon (Ar) gas is introduced into the cavity at a flow rate of 12 sccm, while 1000W power is applied to the silicon (Si) target to form a silicon (Si) layer with a thickness of 4 nm as a high refractive index layer 21, and then the power application to the silicon (Si) target is stopped. Next, argon (Ar) gas is introduced into the cavity at a flow rate of 15 sccm, while 750W power is applied to the molybdenum (Mo) target to form a molybdenum (Mo) layer with a thickness of 3 nm as a low refractive index layer 22, and then the power application to the molybdenum (Mo) target is stopped. The formation operation of the high refractive index layer 21 and the low refractive index layer 22 is repeated as a cycle 40 times to form a periodic stacked structure. After the 40th low-refractive-index layer 22 is formed, a 4 nm thick silicon (Si) layer is formed by the above method, and then a 1 nm thick molybdenum (Mo) layer is formed by the above method, finally obtaining the multilayer reflective film 2.

[0099] The protective film 3 is formed on the multilayer reflective film 2 by DC magnetron sputtering. Specifically, the substrate 1 with the multilayer reflective film 2 formed thereon is placed in a sputtering cavity containing a ruthenium (Ru) target, and argon (Ar) gas is introduced into the cavity at a flow rate of 28 sccm. At the same time, 200W power is applied to the ruthenium (Ru) target to form a ruthenium (Ru) film with a thickness of 2nm as the protective film 3 on the multilayer reflective film 2.

[0100] A 2 nm thick niobium oxide (NbO) film (Nb:O = 2:5 (atomic ratio)) is formed on the protective film 3 as an etching barrier film 4. The method for forming the niobium oxide (NbO) film is as follows: First, the substrate 1 with the multilayer reflective film 2 and the protective film 3 formed above is placed in a sputtering cavity containing a niobium (Nb) target. Argon (Ar) gas is introduced into the cavity at a flow rate of 28 sccm, and at the same time, 200W power is applied to the niobium (Nb) target to form a niobium (Nb) film by DC sputtering. Then, the niobium (Nb) film is heat-treated in air at 150°C for 10 minutes to oxidize it, thereby obtaining the niobium oxide (NbO) film.

[0101] The absorber film 5 is formed on the etch barrier film 4 by DC magnetron sputtering using a sputtering device capable of mounting multiple targets and discharging simultaneously. Specifically, the substrate 1, on which the multilayer reflective film 2, protective film 3, and etch barrier film 4 have been formed, is placed in a sputtering chamber containing ruthenium (Ru) and carbon (C) targets. Argon (Ar) gas is introduced into the chamber at a flow rate of 15 sccm, and power is applied to the ruthenium (Ru) and carbon (C) targets to form a ruthenium carbide (RuC) film with a thickness of 40 nm as the absorber film 5. The carbon (C) content is 15 atoms.

[0102] Through the above steps, a reflective mask blank 100 is obtained, which consists of a substrate 1, a multilayer reflective film 2, a protective film 3, an etching blocking film 4, and an absorber film 5.

[0103] The surface roughness of a 1 μm square region on the surface of the absorber film 5 of the obtained reflective mask blank 100 was measured by atomic force microscopy (AFM), and the results showed that the square root mean roughness (Sq) was 0.14 nm.

[0104] Using ultraviolet light with a wavelength of 213nm, the surface of the absorber film 5 of the obtained reflective mask blank 100 was inspected for defects through the defect detection device of the dark field optical system. The results showed that no false defects caused by the surface roughness of the reflective mask blank 100 were detected.

[0105] The membrane stress (compressive stress is denoted as negative and tensile stress as positive) was determined by measuring the change in warpage (ΔTIR) in the central 142 mm square region of the substrate 1 before and after the formation of the absorber membrane 5. The results showed that the membrane stress of the absorber membrane 5 was -910 MPa.

[0106] For the reflective mask blank 100 of Example 1, the etched blocking film 4 and absorber film 5 were sequentially formed on a quartz glass substrate. The X-ray diffraction pattern of the diffraction angle (2θ) in the range of 30° to 50° was measured by CuKα radiation out-of-plane measurement method. The results showed that the diffraction peak with the strongest intensity was observed at the diffraction angle (2θ) of 45.1°, and its half-width was 4.14°.

[0107] Furthermore, the grain size (grain diameter) calculated using the Scherrer formula is 2.2 nm.

[0108] Grain size (nm) = Kλ / (βcosθ)

[0109] (In the formula, K is the Scherrer constant (taken as 0.95 here), λ is the wavelength of the X-ray used for measurement (0.154nm), β is the full width at half maximum (FWHM) of the diffraction peak (in radians), and θ is the Bragg angle of the diffraction peak (taken as the midpoint of FWHM here).

[0110] [Examples 2-5]

[0111] Except for setting the thickness of the absorber film 5 to 28 nm and setting the carbon (C) content in Examples 2, 3, 4 and 5 to 5 atomic%, 15 atomic%, 26 atomic%, and 40 atomic%, respectively, all other aspects are the same as in Example 1, and a reflective mask blank 100 is prepared.

[0112] The average square root roughness (Sq) of the absorber film 5 of the obtained reflective mask blank 100 was measured using the same method as in Example 1. The results showed that the Sq of Examples 2, 3, 4 and 5 were 0.32 nm, 0.11 nm, 0.11 nm and 0.14 nm, respectively.

[0113] The surface of the absorber film 5 of the obtained reflective mask blank 100 was inspected using the same method as in Example 1. The results showed that no pseudo-defects caused by the surface roughness of the reflective mask blank 100 were detected in Examples 2 to 5.

[0114] The membrane stress of the absorber membrane 5 of the obtained reflective mask blank 100 was measured using the same method as in Example 1. The results showed that the membrane stresses of Examples 2, 3, 4 and 5 were -1600MPa, -930MPa, 90MPa and -210MPa, respectively (compressive stress is recorded as negative and tensile stress as positive).

[0115] The X-ray diffraction patterns of the absorber film 5 were measured using the same method as in Example 1. The results showed that the diffraction peaks with the greatest intensity were observed at diffraction angles (2θ) of 41.8°, 44.9°, 42.6°, and 42.6°, respectively, with half-widths of 1.10°, 4.52°, 4.76°, and 6.58°, respectively.

[0116] Furthermore, the grain sizes of Examples 2, 3, 4, and 5, calculated using the Scherrer formula above, are 8.1 nm, 2.0 nm, 1.9 nm, and 1.4 nm, respectively.

[0117] A comparison of Examples 2 to 5 shows that when the carbon (C) content in absorber membrane 5 is changed, the surface roughness, membrane stress, and grain size will change.

[0118] [Example 6]

[0119] Except for introducing argon (Ar) gas into the sputtering cavity at a flow rate of 32 sccm when forming the absorber film 5, everything else is the same as in Example 2, and a reflective mask blank 100 is obtained.

[0120] The average square root roughness (Sq) of the absorber film 5 of the obtained reflective mask blank 100 was measured using the same method as in Example 1, and the result was 0.21 nm.

[0121] The surface of the absorber film 5 of the obtained reflective mask blank 100 was inspected using the same method as in Example 1. The results showed that no false defects caused by the surface roughness of the reflective mask blank 100 were detected.

[0122] The membrane stress of the absorber membrane 5 of the obtained reflective mask blank 100 was measured using the same method as in Example 1, and the result was -910 MPa (compressive stress is recorded as negative and tensile stress as positive).

[0123] The X-ray diffraction pattern of the absorber film 5 was measured using the same method as in Example 1. The results showed that the strongest diffraction peak was observed at a diffraction angle (2θ) of 41.8°, with a half-width of 1.17°.

[0124] Furthermore, the grain size calculated using the Scherrer formula is 7.7 nm.

[0125] A comparison between Example 2 and Example 6 shows that changing the flow rate of argon (Ar) gas during the formation of absorber membrane 5 will cause changes in membrane stress.

[0126] [Examples 7-9]

[0127] Except for using silicon (Si) target material instead of carbon (C) target material to form ruthenium silicide (RuSi) films with silicon (Si) content of 15 atomic% (Example 7), 29 atomic% (Example 8), and 31 atomic% (Example 9) as absorber film 5, the rest is the same as in Example 1, and a reflective mask blank 100 is prepared.

[0128] The average square root roughness (Sq) of the absorber film 5 of the obtained reflective mask blank 100 was measured using the same method as in Example 1. The results showed that the Sq of Examples 7, 8 and 9 were 0.13 nm, 0.10 nm and 0.11 nm, respectively.

[0129] The surface of the absorber film 5 of the obtained reflective mask blank 100 was inspected using the same method as in Example 1. The results showed that no pseudo-defects caused by the surface roughness of the reflective mask blank 100 were detected in Examples 7 to 9.

[0130] The membrane stress of the absorber membrane 5 of the obtained reflective mask blank 100 was measured using the same method as in Example 1. The results showed that the membrane stresses of Examples 7, 8, and 9 were -1900 MPa, -140 MPa, and -60 MPa, respectively (compressive stress is recorded as negative and tensile stress as positive).

[0131] The X-ray diffraction pattern of the absorber film 5 was measured using the same method as in Example 1. The results showed that the diffraction peaks with the greatest intensity were observed at diffraction angles (2θ) of 43.7°, 43.2° and 42.7° in Examples 7, 8 and 9, respectively, with half-widths of 1.61°, 3.08° and 4.27°, respectively.

[0132] Furthermore, the grain sizes of Examples 7, 8, and 9, calculated using the Scherrer formula above, are 5.6 nm, 2.9 nm, and 2.1 nm, respectively.

[0133] As can be seen from the results of Examples 7 to 9, when the silicon (Si) content in the absorber film 5 is changed, the surface roughness, film stress and grain size will change.

[0134] [Examples 10 and 11]

[0135] Except for replacing the carbon (C) target with a silicon (Si) target and replacing the ruthenium (Ru) target with a platinum (Pt) target to form a platinum silicide (PtSi) film as the absorber film 5 with a silicon (Si) content of 6 atomic% (Example 10) and 9 atomic% (Example 11) and a thickness of 50 nm, the rest is the same as in Example 1, and a reflective mask blank 100 is prepared.

[0136] The average square root roughness (Sq) of the absorber film 5 of the obtained reflective mask blank 100 was measured using the same method as in Example 1. The results showed that the Sq of Examples 10 and 11 were 0.21 nm and 0.25 nm, respectively.

[0137] The surface of the absorber film 5 of the obtained reflective mask blank 100 was tested for defects using the same method as in Example 1. The results showed that no false defects caused by the surface roughness of the reflective mask blank 100 were detected in Examples 10 and 11.

[0138] The membrane stress of the absorber membrane 5 of the obtained reflective mask blank 100 was measured using the same method as in Example 1. The results showed that the membrane stresses of Examples 10 and 11 were -1130 MPa and -170 MPa, respectively (compressive stress is recorded as negative and tensile stress as positive).

[0139] The X-ray diffraction pattern of the absorber film 5 was measured using the same method as in Example 1. The results showed that the diffraction peaks with the greatest intensity were observed at diffraction angles (2θ) of 39.9° and 40.2° in Examples 10 and 11, respectively, with half-widths of 0.61° and 0.72°, respectively.

[0140] Furthermore, the grain sizes of Examples 10 and 11, calculated using the Scherrer formula above, are 14.5 nm and 12.4 nm, respectively.

[0141] [Example 12]

[0142] Except for using a platinum (Pt) target instead of a ruthenium (Ru) target to form a platinum carbide (PtC) film with a carbon (C) content of 19 atomic percent and a thickness of 30 nm as the absorber film 5, all other steps are the same as in Example 1, and a reflective mask blank 100 is prepared.

[0143] The root-square roughness (Sq) of the absorber film 5 of the obtained reflective mask blank 100 was measured using the same method as in Example 1, and the result was 0.17 nm.

[0144] The surface of the absorber film 5 of the obtained reflective mask blank 100 was inspected using the same method as in Example 1. The results showed that no false defects caused by the surface roughness of the reflective mask blank 100 were detected.

[0145] The membrane stress of the absorber membrane 5 of the obtained reflective mask blank 100 was measured using the same method as in Example 1, and the result was -1400 MPa (compressive stress is recorded as negative and tensile stress as positive).

[0146] The X-ray diffraction pattern of the absorber film 5 was measured using the same method as in Example 1. The results showed that the strongest diffraction peak was observed at a diffraction angle (2θ) of 39.6°, with a half-width of 1.11°.

[0147] Furthermore, the grain size calculated using the Scherrer formula is 8.0 nm.

[0148] [Example 13]

[0149] Except for using ruthenium (Ru) targets, platinum (Pt) targets, and silicon (Si) targets to form a platinum-ruthenium silicide (PtRuSi) film with a ruthenium (Ru) content of 33 atomic%, platinum (Pt) content of 47 atomic%, silicon (Si) content of 20 atomic%, and a thickness of 30 nm as the absorber film 5, all other steps are the same as in Example 1 to prepare a reflective mask blank 100.

[0150] The average square root roughness (Sq) of the absorber film 5 of the obtained reflective mask blank 100 was measured using the same method as in Example 1, and the result was 0.12 nm.

[0151] The surface of the absorber film 5 of the obtained reflective mask blank 100 was inspected using the same method as in Example 1. The results showed that no false defects caused by the surface roughness of the reflective mask blank 100 were detected.

[0152] The membrane stress of the absorber membrane 5 of the obtained reflective mask blank 100 was measured using the same method as in Example 1, and the result was -800 MPa (compressive stress is recorded as negative and tensile stress as positive).

[0153] The X-ray diffraction pattern of the absorber film 5 was measured using the same method as in Example 1. The results showed that the strongest diffraction peak was observed at a diffraction angle (2θ) of 40.5°, with a half-width of 1.33°.

[0154] Furthermore, the grain size calculated using the Scherrer formula is 6.7 nm.

[0155] [Example 14]

[0156] Except for using a carbon (C) target instead of a silicon (Si) target to form a platinum-ruthenium carbide (PtRuC) film with a ruthenium (Ru) content of 36 atoms, a platinum (Pt) content of 52 atoms, and a carbon (C) content of 12 atoms as the absorber film 5, all other steps are the same as in Example 13, and a reflective mask blank 100 is prepared.

[0157] The root-square roughness (Sq) of the absorber film 5 of the obtained reflective mask blank 100 was measured using the same method as in Example 1, and the result was 0.16 nm.

[0158] The surface of the absorber film 5 of the obtained reflective mask blank 100 was inspected using the same method as in Example 1. The results showed that no false defects caused by the surface roughness of the reflective mask blank 100 were detected.

[0159] The membrane stress of the absorber membrane 5 of the obtained reflective mask blank 100 was measured using the same method as in Example 1, and the result was -1970 MPa (compressive stress is recorded as negative and tensile stress as positive).

[0160] The X-ray diffraction pattern of the absorber film 5 was measured using the same method as in Example 1. The results showed that the strongest diffraction peak was observed at a diffraction angle (2θ) of 40.1°, with a half-width of 1.20°.

[0161] Furthermore, the grain size calculated using the Scherrer formula is 7.4 nm.

[0162] [Example 15]

[0163] Except for forming the absorber film 5 into a platinum silicide (PtSi) film with a silicon (Si) content of 36 atomic percent and a thickness of 30 nm, the rest is the same as in Example 10, and a reflective mask blank 100 is prepared.

[0164] The root-square roughness (Sq) of the absorber film 5 of the obtained reflective mask blank 100 was measured using the same method as in Example 1, and the result was 0.16 nm.

[0165] The surface of the absorber film 5 of the obtained reflective mask blank 100 was inspected using the same method as in Example 1. The results showed that no false defects caused by the surface roughness of the reflective mask blank 100 were detected.

[0166] The membrane stress of the absorber membrane 5 of the obtained reflective mask blank 100 was measured using the same method as in Example 1, and the result was 30 MPa (tensile stress is positive).

[0167] The X-ray diffraction pattern of the absorber film 5 was measured using the same method as in Example 1. The results showed that the strongest diffraction peak was observed at a diffraction angle (2θ) of 40.4°, with a half-width of 8.11°.

[0168] Furthermore, the grain size calculated using the Scherrer formula is 1.1 nm.

[0169] [Comparative Example 1]

[0170] Except for using only ruthenium (Ru) target material to form a carbon (C)-free ruthenium (Ru) elemental film (Ru film) as absorber film 5, all other steps are the same as in Example 1 to prepare reflective mask blank 100.

[0171] The average square root roughness (Sq) of the absorber film 5 of the obtained reflective mask blank 100 was measured using the same method as in Example 1, and the result was 0.64 nm.

[0172] The same method as in Example 1 was used to detect defects on the surface of the absorber film 5 of the obtained reflective mask blank 100. The results showed that the pseudo defects caused by the surface roughness of the reflective mask blank 100 were fully detected within the detection range, and the detection could not be completed within the normal detection time.

[0173] The membrane stress of the absorber membrane 5 of the obtained reflective mask blank 100 was measured using the same method as in Example 1, and the result was -2820 MPa (compressive stress is denoted as negative).

[0174] The X-ray diffraction pattern of the absorber film 5 was measured using the same method as in Example 1. The results showed that the strongest diffraction peak was observed at a diffraction angle (2θ) of 42.0° with a half-width of 0.46°.

[0175] Furthermore, the grain size calculated using the Scherrer formula is 19.4 nm.

[0176] [Comparative Example 2]

[0177] Except for using only a platinum (Pt) target to form a platinum (Pt) elemental film (Pt film) without silicon (Si) as absorber film 5, all other steps are the same as in Example 11, and a reflective mask blank 100 is prepared.

[0178] The average square root roughness (Sq) of the absorber film 5 of the obtained reflective mask blank 100 was measured using the same method as in Example 1, and the result was 0.59 nm.

[0179] The same method as in Example 1 was used to detect defects on the surface of the absorber film 5 of the obtained reflective mask blank 100. The results showed that the pseudo defects caused by the surface roughness of the reflective mask blank 100 were fully detected within the detection range, and the detection could not be completed within the normal detection time.

[0180] Symbol Explanation 1 substrate 2. Multilayer reflective film 3. Protective film 4. Etching barrier film 5. Absorbent membrane 6. Hard mask 41. Etching barrier film pattern (etching barrier pattern) 51 Absorber membrane pattern (absorber pattern) 100 Reflective Mask Blank 110 Reflective Mask

Claims

1. A reflective mask blank, characterized in that, include: substrate; A multilayer reflective film disposed on a main surface of the substrate for reflecting exposure light; as well as An absorber film disposed above the multilayer reflective film; The absorber membrane contains one or both of ruthenium (Ru) and platinum (Pt), and one or both of carbon (C) and silicon (Si). The root-mean-square roughness (Sq) of the absorber membrane surface is below 0.40 nm.

2. The reflective mask blank according to claim 1, characterized in that: In the X-ray diffraction pattern of the absorber film obtained by out-of-plane determination using CuKα rays, the half-width of the strongest diffraction peak observed between 30° and 50° is not less than 0.60°.

3. The reflective mask blank according to claim 1, characterized in that: in, The absolute value of the membrane stress of the absorber membrane does not exceed 2000 MPa.

4. The reflective mask blank according to any one of claims 1 to 3, characterized in that: in, The absorber membrane contains carbon (C) and its content is between 4 atomic% and 40 atomic%.

5. The reflective mask blank according to any one of claims 1 to 3, characterized in that: in, The absorber membrane contains silicon (Si) in a content of more than 4 atomic% and less than 40 atomic%.

6. The reflective mask blank according to any one of claims 1 to 3, characterized in that: It further includes a protective film disposed between the multilayer reflective film and the absorber film, the protective film comprising one or both of ruthenium (Ru) and rhodium (Rh).

7. The reflective mask blank according to claim 6, characterized in that: It further includes an etching barrier film disposed between the protective film and the absorber film, the etching barrier film comprising at least one selected from niobium (Nb), tantalum (Ta), silicon (Si) and chromium (Cr).

8. The reflective mask blank according to claim 6, characterized in that: It further includes a hard mask film disposed above the absorber film, the hard mask film comprising at least one selected from niobium (Nb), tantalum (Ta), silicon (Si) and chromium (Cr).

9. The reflective mask blank according to claim 7, characterized in that: It further includes a hard mask film disposed above the absorber film, the hard mask film comprising at least one selected from niobium (Nb), tantalum (Ta), silicon (Si) and chromium (Cr).

10. A reflective mask, characterized in that, include: The absorber pattern formed after the absorber film of the reflective mask blank according to any one of claims 1 to 3 is patterned.

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