JP2015056423A - Substrate with multilayer reflection film, reflection type mask blank for euv lithography, reflection type mask for euv lithography, and manufacturing method thereof, and manufacturing method for semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a substrate with a multilayer reflection film which provides a reflection type mask for EUV lithography, for high reflectivity and excellent cleaning resistance.SOLUTION: A substrate with a multilayer reflection film includes a substrate, a multilayer reflection film which is formed on the substrate and in which a layer containing Si as a high refractive index material and a layer containing a low refractive index material are cyclically stacked by a plurality of numbers, a block layer which is formed on the multilayer reflection film and contains silicon oxide and/or RuSi of stoichiometric composition, and a protection film which is formed on the block layer to protect the multilayer reflection film. A surface layer on the side opposite to the substrate of the multilayer reflection film is a layer containing the Si, and the protection film is made from an alloy containing at least two kinds of metal. The alloy is a complete solid solution.

Description

  The present invention relates to a substrate with a multilayer reflective film, which is an original plate for manufacturing an exposure mask used for manufacturing a semiconductor device, a reflective mask blank for EUV lithography obtained from the substrate, a reflective mask for EUV lithography, and The present invention relates to a manufacturing method thereof and a manufacturing method of a semiconductor device.

  With the further demand for higher density and higher precision of VLSI devices in recent years, EUV lithography, which is an exposure technique using extreme ultra violet (hereinafter referred to as EUV) light, is promising. Here, EUV light refers to light in the wavelength band of the soft X-ray region or the vacuum ultraviolet region, and specifically, light having a wavelength of about 0.2 to 100 nm.

  In such a reflective mask, a multilayer reflective film that reflects exposure light is formed on a substrate such as glass or silicon, and an absorber film that absorbs exposure light is formed in a pattern on the multilayer reflective film. Is. In an exposure machine that performs pattern transfer, light incident on a reflective mask mounted thereon is absorbed at a portion where the absorber film pattern is present and is reflected by a multilayer reflective film at a portion where the absorber film pattern is not present. The reflected light image is transferred onto a semiconductor substrate such as a silicon wafer through a reflection optical system.

  In order to achieve higher density and higher accuracy of semiconductor devices using such a reflective mask, the reflective region (surface of the multilayer reflective film) in the reflective mask is higher than the EUV light that is the exposure light. It is necessary to provide reflectivity.

  The multilayer reflective film is a multilayer film in which elements having different refractive indexes are periodically laminated in order to achieve the high reflectivity. Generally, a thin film of a heavy element or a compound thereof, a light element or a compound thereof A multilayer film in which about 40 to 60 cycles of compound thin films are alternately stacked is used. For example, as a multilayer reflective film for EUV light having a wavelength of 13 to 14 nm, a Mo / Si periodic laminated film in which Mo films and Si films are alternately laminated for about 40 cycles is preferably used. Since Mo is easily oxidized by the atmosphere and the reflectance of the multilayer reflective film is lowered, the uppermost layer of the multilayer reflective film is made Si film.

  As a reflective mask used in this EUV lithography, for example, there is a reflective mask for exposure described in Patent Document 1 below. That is, Patent Document 1 discloses a substrate, a reflective layer formed on the substrate and formed of a multilayer film in which two different films are alternately stacked, and a buffer layer formed of a ruthenium film formed on the reflective layer. And a reflection photomask having a predetermined pattern shape and an absorber pattern made of a material capable of absorbing soft X-rays formed on the buffer layer.

  The buffer layer is also called a protective film. When forming the absorber pattern, a part of the absorber film is etched through a resist. However, in order to complete the formation of the absorber pattern, a slight over-etching is performed. The film will also be etched. In this case, a protective film is provided to prevent damage to the multilayer reflective film under the absorber film. As the etching, dry etching is usually employed. For example, when the absorber film is a Ta-based material, the absorber pattern is generally formed by dry etching with a Cl-based gas.

  For the protective film, Zr or B was added to Ru from the viewpoint of suppressing the formation of a diffusion layer between the Si layer on the surface of the multilayer reflective film and the protective film (leading to a decrease in the reflectance of the multilayer reflective film). A protective film made of a Ru alloy has been proposed (Patent Document 2).

  Patent Document 3 discloses a process performed when manufacturing a mask blank and a mirror and a process performed when manufacturing a photomask from the mask blank (for example, cleaning, defect inspection, heating process, dry etching, defect correction). In each step), or during the EUV exposure, the Ru protective layer and further the uppermost layer of the multilayer reflective film (in the case of Mo / Si multilayer reflective film, the Si layer) are oxidized, so that the EUV is formed on the protective layer surface. In order to solve the problem that the EUV light reflectance is lowered when irradiated with light, a Ru layer or a Ru compound layer is adopted as a protective layer, and oxygen is further reduced to 0.1% between the reflective layer and the protective layer. It has been proposed to form an intermediate layer containing 5 to 20 at% and containing 80 to 99.5 at% of Si. Furthermore, Patent Document 3 includes RuB, RuZr, RuSi, and RuNb as the Ru compound.

JP 2002-122981 A JP 2008-016821 A Republished Patent No. 2011-068223

  By the way, in manufacturing a semiconductor device using EUV lithography, the lithography is performed under high vacuum, and impurities such as carbon may be deposited on the reflective mask during or after EUV light irradiation. For this reason, it is necessary to clean the reflective mask after lithography. Usually, since the reflective mask is repeatedly used, the mask cleaning is also repeatedly performed.

  Therefore, the reflective mask is required to have sufficient cleaning resistance. Since a protective film is formed in a portion of the reflective mask where the absorber pattern is not formed, both the absorber pattern and the protective film are required to have cleaning resistance.

However, according to the study of the present inventor, in the reflection type mask of the conventional configuration as disclosed in Patent Documents 1 to 3, when the mask cleaning by the normal RCA cleaning is performed a plurality of times, the exposed reflection It was found that the Ru-based protective film peeled off on the multilayer reflective film in the region. This is because, in the configuration as in Patent Documents 1 and 2, Si moves from the Si layer of the multilayer reflective film to the Ru-based protective film over time and between the grain boundaries of the Ru-based protective film. When it diffuses (and forms Ru silicide (RuSi)), reaches the surface layer of the Ru-based protective film and undergoes an oxidation reaction with a cleaning liquid or gas to generate SiO ₂ , or when the protective film is not dense, This is because the cleaning liquid or gas penetrates into the protective film, and SiO ₂ is generated in the protective film, and the adhesion between Ru and SiO ₂ is low, and these peel off.

  If such film peeling occurs, it may cause new dust generation or non-uniformity of reflectance, so there is a risk that the pattern cannot be accurately transferred when transferring the pattern onto the semiconductor substrate. Yes, it is a serious problem.

  In addition, as a result of investigation by the present inventors, the intermediate layer containing 0.5 to 20 at% oxygen and containing 80 to 99.5 at% Si is Si from the multilayer reflective film as a result of the study by the present inventor. It turned out to be a block layer of movement. However, since the adhesion between the intermediate layer and the protective layer is insufficient, film peeling cannot be sufficiently suppressed.

  Accordingly, an object of the present invention is to provide a substrate with a multilayer reflective film that firstly provides a reflective mask for EUV lithography that has a high reflectivity and is excellent in cleaning resistance. A reflective mask blank for EUV lithography manufactured using a substrate with a reflective film, for example, a reflective mask for EUV lithography obtained from the reflective mask blank, a manufacturing method thereof, and a semiconductor device using the reflective mask It is to provide a manufacturing method.

As a result of studies conducted by the present inventor to solve the above-described problems, it is difficult to suppress the formation of SiO ₂ by oxidation of Si in contact with a gas or a cleaning solution. We thought that suppression was the most important.

  However, as is clear from the configuration disclosed in Patent Document 3, even if an intermediate layer serving as a blocking layer of Si movement is provided between the multilayer reflective film and the protective layer, the intermediate layer and the protective layer As a result, the film peeling cannot be sufficiently suppressed.

  As a result of further investigations on the protective layer, the present inventor has adopted the intermediate layer, and when an alloy that is a solid solution is used as a protective film material, the resulting protective film has improved adhesion to the intermediate layer. It was found that the intermediate layer was excellent and the adhesiveness with the multilayer reflective film was excellent, and further, a specific Ru compound could be used as the intermediate layer, and the present invention was completed.

That is, in order to solve the above problems, the present invention has the following configuration.
(Configuration 1)
A multilayer reflection film formed by periodically laminating a substrate, a layer containing Si as a high refractive index material, and a layer containing a low refractive index material formed on the substrate; and on the multilayer reflection film A block layer formed of silicon oxide and / or RuSi having a stoichiometric composition, and a protective film formed on the block layer for protecting the multilayer reflective film. The substrate with a multilayer reflective film, wherein the surface layer opposite to the substrate is a layer containing Si, and the protective film is made of an alloy containing at least two kinds of metals, and the alloy is a solid solution.

As in the configuration 1, in the substrate with the multilayer reflective film having the multilayer reflective film using Si as the high refractive index material, the outermost surface of the multilayer reflective film is a layer containing Si, and a specific block layer is formed thereon. In addition to the provision of an alloy made of a solid solution as a protective film, Si is prevented from diffusing up to the protective film, and the formation of silicon oxide (SiO ₂ etc.) is suppressed, and at the same time, the protective film and block A substrate with a multilayer reflective film, which is an original plate for producing a reflective mask for EUV lithography, which ensures the adhesion between the layers and the multilayer reflective film and is excellent in cleaning resistance, is obtained.

(Configuration 2)
The alloy includes an alloy composed of ruthenium (Ru) and cobalt (Co), an alloy composed of ruthenium (Ru) and rhenium (Re), an alloy composed of nickel (Ni) and copper (Cu), and gold (Au). An alloy composed of silver and silver (Ag), an alloy composed of silver (Ag) and tin (Sn), an alloy composed of silver (Ag) and copper (Cu), or composed of germanium (Ge) and silicon (Si). The board | substrate with a multilayer reflective film of the structure 1 which is an alloy.

  Examples of the alloy that is a solid solution in the above-described configuration 2 include alloys composed of ruthenium (Ru) and cobalt (Co), alloys composed of ruthenium (Ru) and rhenium (Re), nickel (Ni ) And copper (Cu) alloy, gold (Au) and silver (Ag) alloy, silver (Ag) and tin (Sn) alloy, silver (Ag) and copper (Cu) And alloys made of germanium (Ge) and silicon (Si).

(Configuration 3)
The board | substrate with a multilayer reflective film of the structure 1 or 2 whose said low refractive index material is Mo.

  In order to achieve good reflectivity with respect to EUV light as in the configuration 3, Mo is preferable as the material in the layer including the low refractive index material constituting the multilayer reflective film.

(Configuration 4)
The alloy includes an alloy composed of ruthenium (Ru) and cobalt (Co), an alloy composed of ruthenium (Ru) and rhenium (Re), an alloy composed of nickel (Ni) and copper (Cu), or germanium (Ge). The board | substrate with a multilayer reflective film in any one of the structures 1-3 which is an alloy consisting of and silicon (Si).

  As in the constitution 4, the alloy which is a solid solution is a ruthenium (Ru) and cobalt (Co) alloy, a ruthenium (Ru) and rhenium (Re) alloy from the viewpoint of washing resistance. An alloy made of nickel (Ni) and copper (Cu) and an alloy made of germanium (Ge) and silicon (Si) are preferable.

(Configuration 5)
The board | substrate with a multilayer reflective film in any one of the structures 1-4 whose thickness of the said block layer is 0.2-3 nm.

  As in the above configuration 5, the thickness of the block layer that plays a role in hindering the transition of Si to the protective film usually needs to be 0.2 nm or more, and is preferably 3 nm or less in consideration of the reflectance of EUV light.

(Configuration 6)
In the alloy composed of ruthenium (Ru) and cobalt (Co) and the alloy composed of ruthenium (Ru) and rhenium (Re), the content of ruthenium (Ru) in the alloy is 75 atomic% or more and 99.5. The board | substrate with a multilayer reflective film in any one of the structures 2-5 which is atomic% or less.

  As in the above configuration 6, in the alloy composed of ruthenium (Ru) and cobalt (Co) and the alloy composed of ruthenium (Ru) and rhenium (Re), which are all solid solutions constituting the protective film, ruthenium (Ru) ) In the alloy is preferably 75 atomic% or more and 99.5 atomic% or less from the viewpoint of washing resistance and reflectance characteristics with respect to EUV light.

(Configuration 7)
A reflective mask blank for EUV lithography, comprising: the substrate with a multilayer reflective film according to any one of configurations 1 to 6; and an absorber film that absorbs EUV light and is formed on the protective film of the substrate with the multilayer reflective film. .

  As in the configuration 7, the reflective mask blank for EUV lithography of the present invention has a configuration having an absorber film that absorbs EUV light on the protective film of the multilayer reflective film-coated substrate of the present invention.

(Configuration 8)
The reflective mask blank for EUV lithography according to Configuration 7, further comprising a resist film on the absorber film.

  As in the configuration 8, the reflective mask blank for EUV lithography of the present invention includes an aspect in which a resist film is further provided on the absorber film.

(Configuration 9)
The reflective mask for EUV lithography, comprising the step of patterning the absorber film in the reflective mask blank for EUV lithography according to Configuration 8 through the resist film to form an absorber film pattern on the protective film. Manufacturing method.

  As in the above configuration 9, the absorber film pattern in the reflective mask blank for EUV lithography of the present invention is patterned through the resist film, thereby forming an absorber film pattern on the protective film. By performing this process, the reflective mask for EUV lithography of the present invention having excellent cleaning resistance can be obtained.

(Configuration 10)
A reflective mask for EUV lithography, comprising: the substrate with a multilayer reflective film according to any one of configurations 1 to 6; and an absorber film pattern that absorbs EUV light and is formed on the protective film of the substrate with the multilayer reflective film. .

  As described in the configuration 10, the configuration of the reflective mask for EUV lithography of the present invention absorbs EUV light formed on the substrate with the multilayer reflective film of the present invention and the protective film on the substrate with the multilayer reflective film. And an absorber film pattern.

(Configuration 11)
A transfer pattern is formed on a semiconductor substrate using the reflective mask for EUV lithography obtained by the manufacturing method of the reflective mask for EUV lithography described in Structure 9 or the reflective mask for EUV lithography described in Structure 10. A method for manufacturing a semiconductor device, comprising a step.

  Using the reflective mask for EUV lithography obtained by the manufacturing method of the reflective mask for EUV lithography of the present invention or the reflective mask for EUV lithography of the present invention as described in the above-mentioned constitution 11, transfer onto a semiconductor substrate Various semiconductor devices can be manufactured by forming a pattern and performing other various processes.

  ADVANTAGE OF THE INVENTION According to this invention, the board | substrate with a multilayer reflective film which provides the reflective mask for EUV lithography which was able to obtain a high reflectance and was excellent in washing | cleaning tolerance is provided, Furthermore, it manufactured using the said board | substrate with a multilayer reflective film. A reflective mask blank for EUV lithography, for example, a reflective mask for EUV lithography obtained from the mask blank, a method for manufacturing the same, and a method for manufacturing a semiconductor device using the reflective mask are provided.

It is a schematic diagram which shows the cross section of the board | substrate with a multilayer reflective film of this invention. It is a schematic diagram which shows the cross section of the reflective mask blank for EUV lithography of this invention. It is a schematic diagram which shows the manufacturing method of the reflective mask for EUV lithography of this invention. It is a schematic diagram which shows the process of transferring a pattern to the semiconductor substrate with a resist with a pattern transfer apparatus.

  Hereinafter, the present invention will be described in detail. In the present specification, the term “upper” as used on a layer or the like is not necessarily limited to the case of being formed in contact with the upper surface of the layer or the like, but includes the case of being formed on the upper side in a separated manner. It is used to include the case where an intervening layer exists between the layers.

[Substrate with multilayer reflective film]
FIG. 1 is a schematic view showing a cross section of the multilayer reflective film-coated substrate of the present invention. The substrate 10 with a multilayer reflective film is formed on a substrate 12 by reflecting a multilayer reflective film 14 that reflects EUV light as exposure light, and a Si protective film 18 provided on the multilayer reflective film 14. A blocking layer 16 is provided, and a protective film 18 is provided on the blocking layer 16 to protect the multilayer reflective film 14.

<Substrate 12>
In the case of EUV exposure, the substrate 12 used for the multilayer reflective film-coated substrate 10 of the present invention has a low thermal expansion in the range of 0 ± 5 ppb / ° C. in order to prevent distortion of the absorber film pattern due to heat during exposure. Those having a coefficient are preferably used. As a material having a low thermal expansion coefficient in this range, for example, SiO ₂ —TiO ₂ glass, multicomponent glass ceramics, or the like can be used.

  The main surface of the substrate 12 on which a transfer pattern (an absorber film described later constitutes this) is formed is surface-processed so as to have high flatness from the viewpoint of obtaining at least pattern transfer accuracy and position accuracy. . For example, in the case of EUV exposure, the flatness is preferably 0.1 μm or less, more preferably 0.05 μm or less, particularly in a 132 mm × 132 mm region on the main surface on the side where the transfer pattern of the substrate 12 is formed. Preferably it is 0.03 micrometer or less. Further, the main surface opposite to the side on which the transfer pattern is formed is a surface that is electrostatically chucked when set in the exposure apparatus, and the flatness in the 142 mm × 142 mm region is more preferably 1 μm or less. Is 0.5 μm or less, particularly preferably 0.03 μm or less. In this specification, the flatness is a value representing the warpage (deformation amount) of the surface indicated by TIR (Total Indicated Reading), and a plane determined by the least square method with respect to the substrate surface is defined as a focal plane. It is the absolute value of the height difference between the highest position on the substrate surface above the plane and the lowest position on the substrate surface below the focal plane.

  In the case of EUV exposure, the surface smoothness required for the substrate 12 is that the surface roughness of the main surface on the side where the transfer pattern of the substrate 12 is formed is 0.1 nm or less in terms of root mean square roughness (RMS). It is preferable that The surface smoothness can be measured with an atomic force microscope.

  Furthermore, the substrate 12 preferably has high rigidity in order to prevent deformation due to film stress of a film (such as the multilayer reflective film 14) formed thereon. In particular, those having a high Young's modulus of 65 GPa or more are preferable.

<Multilayer reflective film 14>
In the substrate 10 with the multilayer reflective film of the present invention, the multilayer reflective film 14 is formed on the substrate 12 described above. This multilayer reflective film 14 provides a function of reflecting EUV light in a reflective mask for EUV lithography, and has a multilayer film structure in which elements having different refractive indexes are periodically stacked.

  Generally, a light element or a compound thin film (high refractive index layer) which is a high refractive index material and a heavy element or a compound thin film (low refractive index layer) which is a low refractive index material alternately 40 to 40 A multilayer film laminated for about 60 cycles is used as the multilayer reflective film 14. The multilayer film may be laminated in a plurality of periods, with a laminated structure of a high refractive index layer / low refractive index layer in which a high refractive index layer and a low refractive index layer are laminated in this order from the substrate 12 side as one period. A plurality of periods may be laminated with a laminated structure of a low refractive index layer / a high refractive index layer in which a low refractive index layer and a high refractive index layer are laminated in this order as one period.

  The outermost layer of the multilayer reflective film 14, that is, the surface layer on the opposite side of the multilayer reflective film 14 from the substrate 12 is a high refractive index layer. In the multilayer film described above, the uppermost layer is low when a plurality of high-refractive index layers / low-refractive index layers are stacked in this order from the substrate 12 side. It becomes a refractive index layer. If the low refractive index layer constitutes the outermost surface of the multilayer reflective film 14, it is easily oxidized and the reflectance of the reflective mask is reduced. Therefore, a high refractive index layer is formed on the uppermost low refractive index layer. Thus, the multilayer reflective film 14 is obtained. In the multilayer film described above, the uppermost layer is formed by laminating a plurality of periods with a low-refractive index layer / high-refractive index layer stack structure in which the low-refractive index layer and high-refractive index layer are stacked in this order from the substrate 12 side. Becomes a high refractive index layer, and in this case, the uppermost high refractive index layer becomes the outermost surface of the multilayer reflective film 14.

  In the present invention, a layer containing Si is adopted as the high refractive index layer. The material containing Si may be Si compound containing B, C, N, and O in addition to Si alone. By using a layer containing Si as the high refractive index layer, a reflective mask for EUV lithography having excellent EUV light reflectivity can be obtained. Moreover, since a glass substrate is preferably used as the substrate 12 in the present invention, Si is excellent in adhesion to it.

  In addition, as the low refractive index material, an element selected from Mo, Ru, Rh, and Pt or an alloy thereof is used. For example, as the multilayer reflective film 14 for EUV light having a wavelength of 13 to 14 nm, a Mo / Si periodic laminated film in which Mo films and Si films are alternately laminated for about 40 to 60 periods is preferably used.

  The reflectance of the multilayer reflective film 14 alone is usually 65% or more, and the upper limit is usually 73%. The thickness and period of each constituent layer of the multilayer reflective film 14 may be selected as appropriate according to the exposure wavelength, and are selected so as to satisfy Bragg's law.

  In the multilayer reflective film 14, there are a plurality of high refractive index layers and low refractive index layers, but the thicknesses of the high refractive index layers and the low refractive index layers may not be the same. Moreover, the film thickness of the outermost Si layer of the multilayer reflective film 14 can be adjusted within a range in which the reflectance is not lowered. The film thickness of the outermost Si layer can be 3 to 10 nm.

  A method of forming the multilayer reflective film 14 is known in the art, but can be formed by depositing each layer by, for example, ion beam sputtering. In the case of the Mo / Si periodic multilayer film described above, an Si film having a thickness of about 4 nm is first formed on the substrate 12 using an Si target, for example, by ion beam sputtering, and then about 3 nm in thickness using a Mo target. The Mo film is formed, and this is taken as one period, and is laminated for 40 to 60 periods to form the multilayer reflective film 14 (the outermost layer is a Si film).

<Block layer 16>
In the conventional reflective mask for EUV lithography, a protective film is provided on the multilayer reflective film, and from the viewpoint of suppressing the formation of a diffusion layer between the Si layer and the protective film, a Ru alloy in which Zr or B is added to Ru is used. A protective film has been proposed. However, the diffusion of Si is still insufficient, and Si diffuses into the protective film, undergoes oxidation to form silicon oxide (SiO ₂ etc.), and is used after it is completed as a reflective mask manufacturing process or product The film is peeled off by repeated cleaning in step (1). Alternatively, it has been proposed to form an intermediate layer containing a predetermined amount of Si and O between the Mo / Si multilayer reflective film and the Ru-based protective film (and that the intermediate layer prevents Si migration). However, since such an intermediate layer has insufficient adhesion to the Ru-based protective film, film peeling occurs at these joints.

As described above, it is very difficult to avoid the fact that Si is oxidized and that the adhesion between the silicon oxide (SiO _{2 and the} like) and the Ru-based protective film having the conventional structure is insufficient. As a result of further investigation on the suppression of Si migration and the adhesion between the protective film and the layer made of silicon oxide or the like, the present inventor has adopted a block layer that prevents Si from migrating to the protective film while protecting it. By adopting an alloy that is a solid solution containing at least two kinds of metals as a protective film material, Si diffuses into the protective film and comes into contact with a gas or a cleaning solution to generate silicon oxide (SiO ₂ or the like). In addition, it is possible to prevent the film from peeling off, and to ensure the adhesion of the protective film and the block layer, and the multilayer reflective film below the protective film, and for EUV lithography having high reflectivity and excellent cleaning resistance. It has been found that a reflective mask can be obtained.

The block layer 16 is provided on the multilayer reflective film 14. The block layer 16 includes silicon oxide (SiO _x ) and / or stoichiometric RuSi. The silicon oxide can effectively prevent Si from moving from the Si-containing layer constituting the surface of the multilayer reflective film 14 toward the protective film, and RuSi can also prevent Si from migrating. The block layer 16 can include both silicon oxide and stoichiometric RuSi, in which case the two components may be substantially uniformly dispersed in the block layer 16 or the block layer 16 may be oxidized. It may be a laminate of a layer made of silicon and a layer made of RuSi.

The silicon oxide can be represented by the formula SiO _x , where x is usually 0.25 to 2 (O: 20 to 67 atom%, Si: 33 to 80 atom%), preferably x from the viewpoint of the effect of suppressing Si migration. Is 0.5 to 2 (O: 33 to 67 atom%, Si: 33 to 67 atom%), more preferably x is 1 to 1.8 (O: 50 to 64 atom%, Si: 36 to 50 atom) %).

In RuSi having the stoichiometric composition, Si accounts for 33 atomic% or more and 67 atomic% or less of RuSi. Examples of RuSi having such a stoichiometric composition include RuSi ₂ , Ru ₂ Si ₃ , RuSi, Ru ₄ Si ₃ , Ru ₂ Si, and Ru ₅ Si ₃ . Among the above-mentioned materials, Ru ₄ Si ₃ , Ru ₂ Si and Ru ₅ having a large Ru content with respect to RuSi (Ru: 50 atomic%, Si: 50 atomic%) from the viewpoint of reflectance characteristics with respect to EUV light. Si ₃ is preferred.

  The thickness of the blocking layer 16 is not particularly limited as long as it can block Si transferred from the multilayer reflective film 14 and can secure adhesion with the protective film 18 and the multilayer reflective film 14. From such a viewpoint, the thickness of the block layer 16 is preferably 0.2 nm or more. Further, if the block layer 16 is too thick, the reflectance of the reflective mask may be reduced. Therefore, the thickness of the block layer 16 is preferably 3 nm or less from the viewpoint of suppressing a decrease in EUV light reflectance. Considering the suppression of the transition of Si to the protective film and the reflectivity of EUV light, the thickness of the block layer 16 is preferably 0.2 to 3 nm, more preferably 0.5 to 2 nm.

  Such a block layer 16 can be formed by various known methods capable of forming a thin film of a material constituting the block layer 16. Examples of the method include an ion beam sputtering method, a sputtering method, a reactive sputtering method, Examples include vapor deposition (CVD) and vacuum deposition.

  Further, for example, when the block layer 16 includes silicon oxide, the block layer 16 is heated (annealed) in the multilayer reflective film 14 at any stage of the production of the substrate 10 with the multilayer reflective film. It can be formed by oxidizing Si in the layer containing Si on the surface of 14. Note that the entire surface layer of the multilayer reflective film 14 does not become the block layer 16 containing silicon oxide, but a part thereof is oxidized to become the block layer 16, and the surface of the multilayer reflective film 14 still has Si. It is considered that there is a layer containing

  Further, when the block layer 16 includes stoichiometric RuSi, the block layer 16 forms a film made of Ru on the multilayer reflective film 14, forms a protective film 18 thereon, and It can be formed by heating (annealing). This is because Si moves from the multilayer reflective film 14 to the protective film 18 by heating (the formation of silicon oxide also occurs), but Ru forms a strong silicide with Si and stops the movement of Si at that portion. . Thereby, the block layer 16 containing RuSi having a stoichiometric composition is formed, and at the same time, the movement of Si to the protective film 18 is suppressed. And since the adhesiveness of RuSi formed in this way and the protective film 18 is favorable, the film peeling by insufficient adhesiveness is suppressed.

  When the block layer 16 includes a stoichiometric composition of RuSi, the block layer 16 forms a protective film 18 made of a solid solution alloy containing Ru on the multilayer reflective film 14, and It can also be formed by heating (annealing). In this case, similarly to the above, Si moves from the multilayer reflective film 14 to the protective film 18 by heating, but this forms a strong silicide with Ru in the protective film 18, and the movement of Si in that portion. As a result, the block layer 16 containing a stoichiometric RuSi is formed.

  From the above, especially when the block layer 16 is formed by heating (annealing), the boundary between the block layer 16 and the multilayer reflective film 14 and / or the boundary between the block layer 16 and the protective film 18 is not clear. it is conceivable that. Further, when the block layer 16 containing a stoichiometric composition of RuSi is formed by an ion beam sputtering method or the like, the block layer 16 and the multilayer reflective film 14 are formed in the multilayer reflective film-coated substrate 10 of the present invention immediately after manufacture. The boundary and the boundary between the block layer 16 and the protective film 18 are considered to be clear. However, the boundary layer and the protective layer 18 may be used as a reflective mask for EUV lithography through a subsequent manufacturing process for a reflective mask blank for EUV lithography. In the meantime, it is considered that the transition of Si occurs and the boundary between the block layer 16 and the multilayer reflective film 14 is not clear.

  The heating (annealing) conditions for forming the block layer 16 described above are not particularly limited as long as the desired block layer 16 can be formed. ~ 20 minutes.

<Protective film 18>
A protective film 18 is formed on the block layer 16 formed as described above to protect the multilayer reflective film 14 from dry etching and cleaning in a manufacturing process of a reflective mask for EUV lithography, which will be described later, thereby forming a multilayer. A substrate 10 with a reflective film is completed.

  The protective film 18 is made of an alloy that is a solid solution containing at least two kinds of metals. The total solid solution is an alloy in which each constituent metal melts at any concentration in a liquid phase state or a solid phase state. The inventor of the present invention has a multilayer reflective film-coated substrate that provides a reflective mask for EUV lithography in which the protective film 18 formed of such a material has excellent adhesion to the block layer 16 described above and excellent cleaning resistance. Found to give 10.

  Furthermore, the alloy which is the said solid solution is very stable. In the configuration in which conventional Ru or Ru- (Zr, B) alloy is used as a protective film, when a Cl-based gas is used in dry etching, chloride is generated from the protective film by the gas, followed by the gas. The protective film is reduced or disappears together with the chloride by chemical cleaning. However, since the alloy that is a solid solution of the above-mentioned ratio is very stable, it is hardly subject to chlorination by dry etching using a Cl-based gas, and is excellent in dry etching resistance.

  Examples of the alloy that is a solid solution of all percentages include an alloy composed of ruthenium (Ru) and cobalt (Co), an alloy composed of ruthenium (Ru) and rhenium (Re), and composed of nickel (Ni) and copper (Cu). Alloys, alloys composed of gold (Au) and silver (Ag), alloys composed of silver (Ag) and tin (Sn), alloys composed of silver (Ag) and copper (Cu), and germanium (Ge) and silicon An alloy composed of (Si) is mentioned.

  These alloys may form the protective film 18 alone, or two or more alloys may be used in combination to form the protective film 18.

  In the protective film 18, an element such as oxygen, nitrogen, hydrogen, and carbon may be included in the alloy that is a solid solution constituting the protective film 18 as long as the effects of the present invention are not impaired. .

  Further, the oxide, nitride, hydride, carbide, oxynitride, oxycarbide, oxynitride carbide, etc. of the alloy which is a complete solid solution is formed on the outermost surface of the protective film 18 within a range not impairing the effect of the present invention. May be formed.

  Since the protective film 18 remains as a constituent layer in the reflective mask for EUV lithography, the absorption of EUV light is low (the reflectance of the multilayer reflective film 14 is usually 63% or more (normally 73% in the state where the protective film 18 is formed). Less than%)). From such a viewpoint, the protective film 18 is made of an alloy made of ruthenium (Ru) and cobalt (Co), an alloy made of ruthenium (Ru) and rhenium (Re), nickel (Ni) and copper (Cu). More preferably, an alloy made of germanium (Ge) and silicon (Si), an alloy made of ruthenium (Ru) and cobalt (Co), or an alloy made of ruthenium (Ru) and rhenium (Re). It is particularly preferred that

  From the viewpoint of high reflectivity with respect to EUV light (reflectance of 63% or more) in the reflective mask for EUV lithography obtained from the substrate with a multilayer reflective film of the present invention, an alloy comprising ruthenium (Ru) and cobalt (Co) or In an alloy composed of ruthenium (Ru) and rhenium (Re), the content of Ru in the alloy is preferably 75 atomic% or more and 99.5 atomic% or less, and 90 atomic% or more and 99.5% or less. More preferably, it is 95 atomic% or more and 99.5 atomic% or less. This atomic composition can be measured by Auger electron spectroscopy.

  The present invention uses an alloy containing at least two kinds of metals as the protective film 18 and is an all-solid solution. As a method for forming the protective film 18 made of the alloy, a conventionally known method is used. A method similar to the method for forming the protective film can be employed without any particular limitation. Examples of such a forming method include a magnetron sputtering method and an ion beam sputtering method.

  For example, by changing the type and composition of the sputtering target used in these sputtering methods, the content of each constituent metal in the alloy can be adjusted to a desired value.

  The thickness of the protective film 18 is not particularly limited as long as the protective film 18 can function as the protective film. However, the transmittance of the EUV light (the incident EUV light is transmitted through the protective film 18 and is reflected by the multilayer reflective film 14). The thickness is preferably 1 to 8 nm, and more preferably 1.5 to 5 nm, from the viewpoint of being reflected and reflected light being transmitted through the protective film 18 and emitted.

  As described above, the multilayer reflective film-coated substrate 10 of the present invention includes the substrate 12, the multilayer reflective film 14, the block layer 16, and the protective film 18. In the substrate 10 with the multilayer reflective film, the block layer 16 suppresses film peeling due to various cleanings of the protective film 18, and furthermore, the adhesion between the multilayer reflective film 14, the block layer 16, and the protective film 18 is excellent. Therefore, film peeling due to insufficient adhesion is also suppressed. Thereby, the substrate with a multilayer reflective film 10 of the present invention achieves high reflectivity, specifically 63% or higher reflectivity with respect to EUV light having a wavelength of 13.5 nm, and also has excellent cleaning resistance. Yes.

  Furthermore, the substrate 10 with a multilayer reflective film may have a back conductive film on the main surface of the substrate 12 opposite to the side on which the multilayer reflective film 14 is formed. The back surface conductive film is an electrostatic chuck used as a support means for the substrate 10 with a multilayer reflective film in the production of a mask blank, or a mask at the time of pattern processing or exposure of a reflective mask blank for EUV lithography of the present invention described later. It is formed for the purpose of adsorbing the multilayer reflective film-coated substrate 10 or the mask blank to an electrostatic chuck used as a supporting means for handling, or for the purpose of correcting the stress of the multilayer reflective film 14.

  In the substrate 10 with a multilayer reflective film of the present invention, a base film may be formed between the substrate 12 and the multilayer reflective film 14. The base film is formed for the purpose of improving the smoothness of the surface of the substrate 12, for the purpose of reducing defects, for the purpose of enhancing the reflection of the multilayer reflective film 14, and for correcting the stress of the multilayer reflective film 14.

  In addition, as the substrate 10 with a multilayer reflective film of the present invention, a reference mark serving as a reference for a defect existing position of the substrate 12 or the substrate 10 with a multilayer reflective film is formed on the multilayer reflective film 14 or the protective film 18 by photolithography. In this case, a mode in which a resist film is formed on the multilayer reflective film 14 and the protective film 18 is also included.

[Reflective mask blank for EUV lithography]
FIG. 2 is a schematic view showing a cross section of the reflective mask blank 30 for EUV lithography of the present invention. The mask blank 30 of the present invention is obtained by forming the absorber film 20 that absorbs EUV light on the protective film 18 of the substrate 10 with the multilayer reflective film of the present invention described above.

  The absorber film 20 is dry-etched through a resist to obtain a predetermined absorber film pattern, and a portion that reflects light (EUV light in the present invention) (the protective film 18 and the block layer 16 thereunder and A reflective mask for EUV lithography having a portion where the multilayer reflective film 14 is exposed) and a portion that absorbs light (absorber film pattern) is obtained.

  The material of the absorber film 20 is particularly limited as long as it has a function of absorbing EUV light and can be removed by etching or the like (preferably can be etched by dry etching of chlorine (Cl) or fluorine (F) gas). Not. As such a function, a tantalum (Ta) simple substance or a tantalum compound containing Ta as a main component can be preferably used.

  The absorber film 20 composed of such tantalum or a tantalum compound can be formed by a known method such as a magnetron sputtering method such as a DC sputtering method or an RF sputtering method. For example, the absorber film 20 can be formed on the protective film 18 by sputtering using a target containing tantalum and boron and using an argon gas to which oxygen or nitrogen is added.

  The tantalum compound is usually an alloy of Ta. The crystalline state of the absorber film 20 is preferably an amorphous or microcrystalline structure from the viewpoint of smoothness and flatness. If the surface of the absorber film 20 is not smooth and flat, the edge roughness of the absorber film pattern increases, and the dimensional accuracy of the pattern may deteriorate. The surface roughness of the absorber film 20 is preferably 0.5 nmRms or less, more preferably 0.4 nmRms or less and 0.3 nmRms or less.

  As the tantalum compound, a compound containing Ta and B, a compound containing Ta and N, a compound containing Ta, O and N, a compound containing Ta and B, and further containing at least one of O and N A compound containing Ta and Si, a compound containing Ta, Si and N, a compound containing Ta and Ge, a compound containing Ta, Ge and N, and the like can be used.

  Ta is a material having a large EUV light absorption coefficient and can be easily dry-etched with a chlorine-based gas or a fluorine-based gas. Therefore, Ta is an excellent absorber film material. Further, by adding B, Si, Ge or the like to Ta, an amorphous material can be easily obtained, and the smoothness of the absorber film 20 can be improved. Further, if N or O is added to Ta, the resistance of the absorber film 20 to oxidation is improved, so that it is possible to improve the stability over time.

  On the other hand, the absorber film material can be microcrystallized by adjusting the substrate heating temperature during the formation of the absorber film 20 and the sputtering gas pressure during the film formation.

  Moreover, as a material which comprises the absorber film | membrane 20, materials, such as WN, TiN, Ti other than tantalum or a tantalum compound, are mentioned.

  The absorber film 20 described above is preferable in that the absorption coefficient is 0.025 or more, further 0.030 or more with respect to the wavelength of the exposure light, from the viewpoint that the thickness of the absorber film 20 can be reduced.

  The thickness of the absorber film 20 may be any thickness that can sufficiently absorb EUV light as exposure light, but is usually about 30 to 100 nm.

  The reflective mask blank 30 for EUV lithography of the present invention includes an embodiment in which a resist film 22 for pattern formation by dry etching is formed on the absorber film 20. This mode is shown in FIG.

  Further, the reflective mask blank 30 for EUV lithography of the present invention includes an embodiment in which a hard mask film is formed between the absorber film 20 and the resist film 22. The hard mask film has a mask function when the absorber film 20 is patterned, and is made of a material having a different etching selectivity from the absorber film 20. When the absorber film 20 is composed of tantalum or a tantalum compound, a material such as chromium or a chromium compound is selected as a material for forming the hard mask film. Examples of the chromium compound include a material containing Cr and at least one element selected from N, O, C, and H.

  In the reflective mask blank 30 for EUV lithography, a back surface conductive film may be formed on the surface opposite to the surface facing the multilayer reflective film 14 of the substrate 12 for the purpose of electrostatic chuck as described above. Good. The electrical characteristics required for the back conductive film are usually 100Ω / □ or less. A method for forming the back conductive film is known, and can be formed by using a target of metal or alloy such as chromium (Cr) or tantalum (Ta), for example, by magnetron sputtering or ion beam sputtering. Although the thickness of a back surface electrically conductive film is not specifically limited as long as the said objective is achieved, Usually, it is 10-200 nm.

  As will be described below, the reflective mask blank 30 for EUV lithography of the present invention is further processed to obtain a reflective mask for EUV lithography, and this reflective mask is usually subjected to pattern inspection and correction. Even in the case of a reflective mask that applies EUV light to exposure light, light having a longer wavelength is often used as inspection light when performing pattern inspection as compared to EUV light having a wavelength of 193 nm, 257 nm, or the like. In order to cope with inspection light having a long wavelength, it is necessary to reduce the surface reflection of the absorber film 20. In this case, the absorber film 20 has a structure in which an absorber layer mainly having a function of absorbing EUV light and a low reflection layer mainly having a function of reducing surface reflection with respect to inspection light are laminated from the substrate 12 side. Good. As the material for forming the low reflection layer, when the absorber layer is a material mainly composed of Ta, a material obtained by adding O to Ta or TaB is preferable.

[Reflective mask for EUV lithography]
By using the reflective mask blank 30 for EUV lithography of the present invention described above, the reflective mask for EUV lithography of the present invention can be manufactured. For the production of the reflective mask for EUV lithography of the present invention, a photolithography method capable of performing high-definition patterning is most suitable.

  Hereinafter, a method of manufacturing the reflective mask for EUV lithography of the present invention by patterning the absorber film 20 in the reflective mask blank 30 for EUV lithography through a resist film using a photolithography method will be described. Moreover, the schematic diagram of the said method is shown in FIG. In FIG. 3, the same components are denoted by reference numerals, and the other identical components are not denoted by reference numerals.

  First, a resist film 22 is formed on the absorber film 20 of the mask blank 30 (FIG. 3A) in which the substrate 12, the multilayer reflective film 14, the block layer 16, the protective film 18, and the absorber film 20 are formed in this order. (FIG. 3B). Since the one having the resist film 22 formed thereon is also the reflective mask blank 30 for EUV lithography of the present invention, the process may be started from here. A desired pattern is drawn (exposed) on the resist film 22, and further developed and rinsed to form a predetermined resist pattern 22a (FIG. 3C).

  By performing dry etching with an etching gas using the resist pattern 22a as a mask, a portion of the absorber film 20 that is not covered with the resist pattern 22a is etched, and the absorber film pattern 20a is formed on the protective film 18. (FIG. 3D).

As the etching gas, a chlorine-based gas such as Cl ₂ , SiCl ₄ , CHCl ₃ , CCl ₄ , a mixed gas containing these chlorine-based gas and O ₂ at a predetermined ratio, a chlorine-based gas, and He are predetermined. Mixed gas containing a ratio, chlorine-based gas, and mixed gas containing Ar in a predetermined ratio, CF ₄ , CHF ₃ , C ₂ F ₆ , C ₃ F ₆ , C ₄ F ₆ , C ₄ F ₈ , CH ₂ F ₂ , CH ₃ F, C ₃ F ₈ , SF ₆ , F and other fluorine-based gases, mixed gases containing these fluorine-based gases and O ₂ at a predetermined ratio, mixed gases including fluorine-based gas and He at a predetermined ratio, A mixed gas containing a fluorine-based gas and Ar in a predetermined ratio is exemplified.

  Then, for example, after removing the resist pattern 22a with a resist stripper, wet cleaning using an acidic or alkaline aqueous solution is performed to obtain a reflective mask 40 for EUV lithography that achieves high reflectivity.

[Method for Manufacturing Semiconductor Device]
A transfer pattern based on the absorber film pattern 20a of the mask is formed on the semiconductor substrate by the lithography technique using the reflective mask 40 for EUV lithography of the present invention described above, and the semiconductor is subjected to various other processes. A semiconductor device in which various patterns and the like are formed on a substrate can be manufactured.

  As a more specific example, a method of transferring a pattern by EUV light to a semiconductor substrate 56 with a resist using a reflective mask 40 for EUV lithography by the pattern transfer apparatus 50 shown in FIG. 4 will be described.

  The pattern transfer apparatus 50 on which the reflective mask 40 for EUV lithography is mounted is generally composed of a laser plasma X-ray source 52, a reflective mask 40, a reduction optical system 54, and the like. As the reduction optical system 54, an X-ray reflection mirror is used.

  By the reduction optical system 54, the pattern reflected by the reflective mask 40 is usually reduced to about ¼. For example, a wavelength band of 13 to 14 nm is used as the exposure wavelength, and the optical path is preset in vacuum. In such a state, EUV light obtained from the laser plasma X-ray source 52 is incident on the reflective mask 40, and the light reflected here is transferred onto the resist-coated semiconductor substrate 56 through the reduction optical system 54.

  The light incident on the reflective mask 40 is absorbed and not reflected by the absorber film in a portion where the absorber film pattern 20a is present, while the light incident on the portion where the absorber film pattern 20a is not present is reflected in the multilayer reflective film 14. Is reflected by. In this way, an image formed by the light reflected from the reflective mask 40 enters the reduction optical system 54. The exposure light that has passed through the reduction optical system 54 forms a transfer pattern on the resist layer on the semiconductor substrate 56 with resist. The resist pattern can be formed on the semiconductor substrate 56 with resist by developing the exposed resist layer.

Then, by performing etching or the like using the resist pattern as a mask, for example, a predetermined wiring pattern can be formed on the semiconductor substrate.
A semiconductor device is manufactured through such a process and other necessary processes.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, these Examples do not limit this invention at all.

Example 1
<Manufacture of substrate with multilayer reflective film>
The substrate to be used is a SiO ₂ —TiO ₂ glass substrate (6 inch square, thickness 6.35 mm). The end surface of the glass substrate was chamfered and ground, and further subjected to rough polishing with a polishing liquid containing cerium oxide abrasive grains. The glass substrate after these treatments was set on a carrier of a double-side polishing apparatus, and precision polishing was performed under predetermined polishing conditions using an alkaline aqueous solution containing colloidal silica abrasive grains as a polishing liquid. After precision polishing, the glass substrate was washed.

  A glass substrate for a reflective mask blank for EUV lithography was produced as described above. The surface roughness of the main surface of the obtained glass substrate was as good as 0.10 nm or less in terms of root mean square roughness (RMS). Further, the flatness was as good as 30 nm or less in a measurement region of 132 mm × 132 mm.

Next, a back conductive film made of CrN was formed on the back surface of the reflective mask blank glass substrate for EUV lithography under the following conditions by magnetron sputtering.
Back surface conductive film formation conditions: Cr target, Ar + N ₂ gas atmosphere (Ar: N ₂ = 90%: 10%), film composition (Cr: 90 atomic%, N: 10 atomic%), film thickness 20 nm

  Next, a multilayer reflective film was formed as follows on the main surface opposite to the side on which the back conductive film was formed of the reflective mask blank glass substrate for EUV lithography. As the multilayer reflective film formed on the glass substrate, a Mo film / Si film periodic multilayer reflective film was employed in order to obtain a multilayer reflective film suitable for an exposure light wavelength band of 13 to 14 nm.

  That is, the multilayer reflective film was formed by alternately stacking Mo layers and Si layers on a substrate by ion beam sputtering (using Ar) using a Mo target and a Si target.

  First, a Si film was formed with a thickness of 4.2 nm, and then a Mo film was formed with a thickness of 2.8 nm. This was taken as one cycle, and 40 cycles were laminated in the same manner. Finally, a Si film was formed with a thickness of 4.0 nm to form a multilayer reflective film.

The sample on which the multilayer reflective film was formed in this way was annealed in the atmosphere (at 200 ° C. for 10 minutes) to form a SiO ₂ film on the surface of the multilayer reflective film (thickness 1 nm).

Subsequently, a RuCo target (Ru: 97 atomic%, Co: 3 atomic%) is used, and RuCo (Ru: 97 atomic%, Co is formed on the SiO ₂ film of the multilayer reflective film by DC magnetron sputtering in an Ar gas atmosphere. : 3 atomic%), a Ru-based protective film was formed (thickness 2.5 nm).

  The thus obtained substrate with a multilayer reflective film had a high reflectance of 63.7% with respect to EUV light having a wavelength of 13.5 nm on the surface of the Ru-based protective film.

<Manufacture of reflective mask blank for EUV lithography>
An absorber film composed of a laminated film of TaBN (thickness 56 nm) and TaBO (thickness 14 nm) is formed by DC magnetron sputtering on the Ru-based protective film of the substrate with a multilayer reflective film obtained as described above, and EUV lithography is performed. A reflective mask blank for use was manufactured. The TaBN film uses a TaB target and is reactive sputtering in a mixed gas atmosphere of Ar gas and N ₂ gas. The TaBO film uses a TaB target and is reactive in a mixed gas atmosphere of Ar gas and O ₂ gas. Formed.

(Example 2)
<Manufacture of substrate with multilayer reflective film>
Instead of forming an SiO ₂ film on the surface of the multilayer reflective film by annealing in the air, a Si target is used, and an SiO ₂ film (on the multilayer reflective film is formed on the multilayer reflective film by RF sputtering in a mixed gas atmosphere of Ar gas and O ₂ gas. A substrate with a multilayer reflective film was produced in the same manner as in Example 1 except that the thickness was 1.0 nm.

  In the obtained substrate with a multilayer reflective film, the reflectance with respect to EUV light with a wavelength of 13.5 nm on the surface of the Ru-based protective film was as high as 63.5%.

<Manufacture of reflective mask blank for EUV lithography>
Using the substrate with a multilayer reflective film obtained as described above, in the same manner as in Example 1, an absorption comprising a laminated film of TaBN (thickness 56 nm) and TaBO (thickness 14 nm) on a Ru-based protective film. A body film was formed by DC magnetron sputtering to produce a reflective mask blank for EUV lithography. The TaBN film and the TaBO film were formed by reactive sputtering in the same manner as in Example 1.

(Example 3)
<Manufacture of substrate with multilayer reflective film>
After forming the SiO ₂ film on the surface of the multilayer reflective film by annealing in the air, and before forming the Ru-based protective film, using a stoichiometric Ru ₂ Si target, DC magnetron sputtering in an Ar gas atmosphere A substrate with a multilayer reflective film was produced in the same manner as in Example 1 except that a Ru ₂ Si film (thickness: 1.0 nm) was formed on the SiO ₂ film.

  In the obtained substrate with a multilayer reflective film, the reflectance with respect to EUV light having a wavelength of 13.5 nm on the surface of the Ru-based protective film was as high as 63.1%.

<Manufacture of reflective mask blank for EUV lithography>
Using the substrate with a multilayer reflective film obtained as described above, in the same manner as in Example 1, an absorption comprising a laminated film of TaBN (thickness 56 nm) and TaBO (thickness 14 nm) on a Ru-based protective film. A body film was formed by DC magnetron sputtering to produce a reflective mask blank for EUV lithography. The TaBN film and the TaBO film were formed by reactive sputtering in the same manner as in Example 1.

Example 4
After forming the multilayer reflective film on a glass substrate in the same manner as in Example 1, using Ru 2 _Si target stoichiometry (using Ar) ion beam sputtering by Ru 2 _Si film multilayer reflective film Formed above (thickness 1.0 nm). Further, a RuCo target (Ru: 97 atomic%, Co: 3 atomic%) was used, and RuCo (Ru: 97 atomic%, Co: 3 atomic%) was formed on the Ru ₂ Si film by ion beam sputtering (using Ar). (Ru-based protective film) was formed (thickness 2.5 nm) to produce a substrate with a multilayer reflective film.

  The thus obtained substrate with a multilayer reflective film had a high reflectance of 64.1% with respect to EUV light having a wavelength of 13.5 nm on the surface of the Ru-based protective film.

<Manufacture of reflective mask blank for EUV lithography>
Using the substrate with a multilayer reflective film obtained as described above, in the same manner as in Example 1, an absorption comprising a laminated film of TaBN (thickness 56 nm) and TaBO (thickness 14 nm) on a Ru-based protective film. A body film was formed by DC magnetron sputtering to produce a reflective mask blank for EUV lithography. The TaBN film and the TaBO film were formed by reactive sputtering in the same manner as in Example 1.

(Comparative Example 1)
<Manufacture of substrate with multilayer reflective film>
After the multilayer reflective film was formed, no annealing treatment was performed in the atmosphere, and a Ru target was used as a Ru-based protective film, and a Ru film composed of a Ru film was formed on the multilayer reflective film by ion beam sputtering (using Ar). A substrate with a multilayer reflective film was produced in the same manner as in Example 1 except that a system protective film was formed (thickness 2.5 nm).

  The thus obtained substrate with a multilayer reflective film had a high reflectance of 64.5% with respect to EUV light having a wavelength of 13.5 nm on the surface of the Ru-based protective film.

<Manufacture of reflective mask blank for EUV lithography>
Using the substrate with a multilayer reflective film obtained as described above, in the same manner as in Example 1, an absorption comprising a laminated film of TaBN (thickness 56 nm) and TaBO (thickness 14 nm) on a Ru-based protective film. A body film was formed by DC magnetron sputtering to produce a reflective mask blank for EUV lithography. The TaBN film and the TaBO film were formed by reactive sputtering in the same manner as in Example 1.

[Mask cleaning resistance test]
A reflective mask for EUV lithography was manufactured using each of the reflective mask blanks for EUV lithography obtained in Examples 1 to 4 and Comparative Example 1. Specifically, it is as follows.

  First, a resist film for electron beam drawing was formed on the absorber film of the reflective mask blank, and a predetermined pattern was drawn using an electron beam drawing gas. After drawing, a predetermined development process was performed to form a resist pattern on the absorber film.

Next, using this resist pattern as a mask, the upper TaBO film is dry-etched with a fluorine-based gas (CF ₄ gas) and the lower TaBN film is dry-etched with a chlorine-based gas (Cl ₂ gas) to form a transfer pattern on the absorber film. The absorber film pattern was formed.

  Further, the resist pattern remaining on the absorber film pattern was removed with hot sulfuric acid to obtain a reflective mask. In this way, 20 reflective masks were produced from each of Examples 1 to 4 and Comparative Example 1.

  The obtained reflective mask was repeatedly subjected to general RCA cleaning, and the cleaning resistance of the reflective mask was evaluated. The film peeling state of the protective film was observed with an SEM (scanning electron microscope). The results are shown in Table 1 below.

DESCRIPTION OF SYMBOLS 10 Substrate with multilayer reflective film 12 Substrate 14 Multilayer reflective film 16 Block layer 18 Protective film 20 Absorber film 20a Absorber film pattern 22 Resist film 22a Resist pattern 30 Reflective mask blank 40 for EUV lithography Reflective mask 50 pattern for EUV lithography Transfer device 52 Laser plasma X-ray source 54 Reduction optical system 56 Resisted semiconductor substrate

Claims (11)

A substrate,
A multilayer reflective film in which a plurality of layers containing Si as a high refractive index material and a layer containing a low refractive index material are periodically laminated;
A blocking layer comprising silicon oxide and / or stoichiometric RuSi formed on the multilayer reflective film;
A protective film that is formed on the block layer and protects the multilayer reflective film;
The surface layer opposite to the substrate of the multilayer reflective film is a layer containing Si,
The said protective film consists of an alloy containing an at least 2 sort (s) of metal, This alloy is a board | substrate with a multilayer reflective film which is a complete solution. The alloy is
Alloy composed of ruthenium (Ru) and cobalt (Co), alloy composed of ruthenium (Ru) and rhenium (Re), alloy composed of nickel (Ni) and copper (Cu), gold (Au) and silver (Ag) ), An alloy composed of silver (Ag) and tin (Sn), an alloy composed of silver (Ag) and copper (Cu), or an alloy composed of germanium (Ge) and silicon (Si). The substrate with a multilayer reflective film according to claim 1.   The substrate with a multilayer reflective film according to claim 1, wherein the low refractive index material is Mo. The alloy is
An alloy composed of ruthenium (Ru) and cobalt (Co), an alloy composed of ruthenium (Ru) and rhenium (Re), an alloy composed of nickel (Ni) and copper (Cu), or germanium (Ge) and silicon (Si) The board | substrate with a multilayer reflective film in any one of Claims 1-3 which is an alloy which consists of these.   The board | substrate with a multilayer reflective film in any one of Claims 1-4 whose thickness of the said block layer is 0.2-3 nm.   In the alloy composed of ruthenium (Ru) and cobalt (Co) and the alloy composed of ruthenium (Ru) and rhenium (Re), the content of ruthenium (Ru) in the alloy is 75 atomic% or more and 99.5. The board | substrate with a multilayer reflective film in any one of Claims 2-5 which is atomic% or less.   A reflective mask for EUV lithography comprising the substrate with a multilayer reflective film according to any one of claims 1 to 6 and an absorber film for absorbing EUV light, which is formed on a protective film in the substrate with the multilayer reflective film. blank.   The reflective mask blank for EUV lithography according to claim 7, further comprising a resist film on the absorber film.   The reflective film for EUV lithography, comprising the step of patterning the absorber film in the reflective mask blank for EUV lithography according to claim 8 through the resist film to form an absorber film pattern on the protective film. Mask manufacturing method.   A reflective type for EUV lithography, comprising: the substrate with a multilayer reflective film according to any one of claims 1 to 6; and an absorber film pattern that absorbs EUV light and is formed on the protective film of the substrate with the multilayer reflective film. mask.   A transfer pattern is formed on a semiconductor substrate using the reflective mask for EUV lithography obtained by the method for manufacturing a reflective mask for EUV lithography according to claim 9 or the reflective mask for EUV lithography according to claim 10. A method for manufacturing a semiconductor device, comprising forming a semiconductor device.

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