JP2015073013A - Method of manufacturing reflective mask blank for euv lithography - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing an EUV mask blank including a procedure for adjusting the EUV light beam reflectance of the absorber layer of an EUV mask blank, by using an ion injection method.SOLUTION: In a method for manufacturing a reflective mask blank for EUV lithography (EUVL) for forming a reflective layer reflecting the EUV light on a substrate, and forming an absorption layer for absorbing the EUV light on the reflective layer, the absorption layer makes the absorption factor for the EUV light after ion implantation higher than that before ion implantation, by implanting the ions of an element having an extinction coefficient for the EUV light higher than that of a sputtering formation film, in the sputtering formation film formed by sputtering.

Description

  The present invention relates to a method of manufacturing a reflective mask blank for EUV (Extreme Ultraviolet) lithography used in semiconductor manufacturing or the like.

  2. Description of the Related Art Conventionally, in the semiconductor industry, a photolithography method using visible light or ultraviolet light has been used as a technique for transferring a fine pattern necessary for forming an integrated circuit having a fine pattern on a silicon substrate or the like. However, while miniaturization of semiconductor devices is accelerating, the limits of conventional photolithography methods have been approached. In the case of the photolithography method, the resolution limit of the pattern is about ½ of the exposure wavelength, and it is said that the immersion wavelength is about ¼ of the exposure wavelength, and the ArF laser (wavelength: 193 nm) is used. Even if the immersion method is used, the exposure wavelength is expected to be about 45 nm. Therefore, EUV lithography, which is an exposure technique using EUV light having a wavelength shorter than that of an ArF laser, is promising as a next-generation exposure technique using a wavelength shorter than 45 nm. In this specification, EUV light refers to light having a wavelength in the soft X-ray region or vacuum ultraviolet region, and specifically refers to light having a wavelength of about 10 to 20 nm, particularly about 13.5 nm ± 0.3 nm.

  Since EUV light is easily absorbed by any material and the refractive index of the material is close to 1 at this wavelength, a conventional refractive optical system such as photolithography using visible light or ultraviolet light cannot be used. For this reason, in the EUV light lithography, a reflective optical system, that is, a reflective photomask and a mirror are used.

The mask blank is a laminated body before patterning used for photomask manufacturing. The EUV mask blank has a structure in which a reflective layer that reflects EUV light and an absorption layer that absorbs EUV light are formed in this order on a glass substrate or the like.
A protective layer is usually formed between the reflection layer and the absorption layer. The protective layer is provided for the purpose of protecting the reflective layer so that the reflective layer is not damaged by an etching process performed for the purpose of patterning the absorption layer.

As the reflective layer, a molybdenum (Mo) layer as a low refractive index layer having a low refractive index characteristic for EUV light, and silicon (Si) as a high refractive index layer having a high refractive index characteristic for EUV light. A Mo / Si multilayer reflective film in which the light reflectance when the EUV light is irradiated onto the layer surface by alternately laminating the layers is usually used.
For the absorption layer, a material having a high absorption coefficient for EUV light, specifically, a material mainly composed of, for example, chromium (Cr) or tantalum (Ta) is used.

In recent years, in a mask blank for a reflective photomask, as the pattern becomes finer, the influence of shadowing (deterioration of pattern accuracy) due to the thickness of the absorption layer has become a problem, and the influence of this shadowing is suppressed. Therefore, a reduction in the thickness of the absorption layer has been studied.
Although it is possible to reduce the thickness of the absorption layer to some extent by adjusting the composition of the formed absorption layer, it is difficult to satisfy all the required characteristics for the absorption layer by adjusting the composition of the absorption layer.

  If the reflectance (hereinafter referred to as “EUV reflectance”) for EUV light incident on the absorption layer can be adjusted after the formation of the absorption layer, the thin film of the absorption layer while satisfying other required characteristics for the absorption layer It is thought that it can be achieved.

  As means for changing the physical properties of a thin film mainly composed of a metal material such as an absorption layer after the thin film is formed, an element or compound other than the constituent material of the thin film is implanted as ions into the formed thin film. Thus, there is an ion implantation method for changing the physical properties and chemical properties of the thin film.

During the production of an EUV mask blank, a sputtering method is used to form a multilayer reflective film and an absorption layer. In general, a vacuum film formation method such as sputtering can produce a material having a composition and structure that cannot be obtained in a thermodynamic equilibrium state. The reason is that the source material is deposited with a large energy of several thousand degrees C. or more (up to several hundred thousand degrees C.) when converted into temperature with respect to the substrate temperature, and at that time, the energy is rapidly lost.
The raw material implanted by the ion implantation method has an energy about 1000 times higher than the energy of the raw material by the vacuum film formation method, and therefore does not accumulate on the surface but enters the material. Since the intrusion region has a composition and structure that cannot be obtained even by the vacuum film formation method, the ion implantation method can be said to be a method capable of forming a layer of a material that cannot be formed by the vacuum film formation method. For this reason, the physical characteristics and chemical characteristics of the thin film can be changed by implanting elements or compounds other than the constituent materials of the thin film as ions.

Patent Documents 1 and 2 disclose a method of changing physical properties and chemical properties of an absorption layer by ion implantation into the absorption layer of the transmission type photomask.
In the methods described in Patent Documents 1 and 2, rare gas ions such as argon ions are implanted into the absorption layer for the purpose of adjusting the stress of the X-ray absorption layer.
Patent Documents 3 to 4 disclose methods of changing physical characteristics and chemical characteristics of a mask substrate by ion implantation into the mask substrate of the transmission type photomask. In the method described in Patent Document 3, boron, phosphorus, aluminum, gallium, indium, any suitable substance that modifies the optical characteristics of the mask substrate for the purpose of adjusting the refractive index and transmittance of the transmissive photomask. Arsenic and antimony are injected. In the method described in Patent Document 4, phosphorus or boron is ion-implanted for the purpose of improving the etching characteristics of the glass substrate of the transmission mask.
Further, Patent Document 5 discloses a method for changing the EUV reflectance of a reflective multilayer film by ion implantation into a part of the reflective multilayer film of the EUV mask. In the method described in Patent Document 5, oxygen is ion-implanted into a part of the reflective multilayer film.

JP 7-78754 A Japanese Patent No. 28223276 Japanese Patent No. 3205241 Japanese Patent No. 2616562 JP 2006-191076 A

As described above, in the case of the EUVL reflective mask blank and EUVL reflective mask, no attempt has been made to ion-implant the absorption layer for the purpose of adjusting the EUV reflectance of the absorption layer.
The present invention aims to provide a method for manufacturing an EUV mask blank including a procedure for adjusting the EUV reflectivity of an absorption layer of an EUV mask blank using an ion implantation method in order to solve the above-described problems of the prior art. And

To achieve the above object, the present invention provides a reflective mask for EUV lithography (EUVL) in which a reflective layer that reflects EUV light is formed on a substrate, and an absorbing layer that absorbs EUV light is formed on the reflective layer. A method of manufacturing a blank,
The absorption layer is formed by implanting ions of an element having a higher extinction coefficient with respect to EUV light than the sputtering formation film into a sputtering formation film formed by a sputtering method. Provided is a method (1) for producing a reflective mask blank for EUVL, which is formed so as to have a high absorption coefficient for EUV light after implantation.

In the present invention, a reflective layer that reflects EUV light is formed on a substrate, a protective layer for the reflective layer is formed on the reflective layer, and an absorption layer that absorbs EUV light is formed on the protective layer. A method of manufacturing a reflective mask blank for EUV lithography (EUVL) comprising:
The absorption layer is formed by implanting ions of an element having a higher extinction coefficient with respect to EUV light than the sputtering formation film into a sputtering formation film formed by a sputtering method. Provided is a method (2) for producing a reflective mask blank for EUVL, which is formed so as to have a high absorption coefficient for EUV light after implantation.

In the EUV mask blank manufacturing methods (1) and (2) of the present invention, the reflectance of the central wavelength (wavelength 13.5 nm) in the EUV wavelength region on the surface of the sputtering film is R _i before ion implantation, When R _{f is} assumed after the implantation, the value of the change rate of EUV reflectance before and after ion implantation ((R _f −R _i ) × 100 / R _i ) is preferably −5% or less.

Method for producing an EUV mask blank of the present invention (1), (2), at the center wavelength of the EUV wavelength region (wavelength 13.5 nm), the extinction coefficient of the sputtered forming film, a pre-ion implantation and k _i, when the post-ion implantation and k _f, the value of the extinction coefficient of the rate of change before and after the ion implantation _{((k f -k i) /} k i) is preferably 0.03 or more.

Method for producing an EUV mask blank of the present invention (1), (2), at the center wavelength in the EUV wavelength region (wavelength 13.5 nm), the refractive index of the sputtered forming film, a pre-ion implantation and n _i, ion When n _{f is} assumed after the implantation, it is preferable that the amount of change in refractive index (n _f −n _i ) before and after ion implantation satisfies the following formula.
−0.1 ≦ n _f −n _i ≦ 0.1

  In the manufacturing methods (1) and (2) of the EUV mask blank of the present invention, the sputtering film is a material mainly composed of tantalum (Ta), a material mainly composed of palladium (Pd), and chromium (Cr). It is preferably made of any one selected from a material mainly containing ruthenium (Ru).

  In the EUV mask blank manufacturing methods (1) and (2) of the present invention, ions to be implanted into the sputtering film are generated from at least one of the elements included in Groups 10 to 15 of the periodic table. It is preferable.

  In the EUV mask blank manufacturing methods (1) and (2) of the present invention, ions implanted into the sputtering film are nickel (Ni), copper (Cu), zinc (Zn), palladium (Pd), indium ( From at least one element selected from the group consisting of In), tin (Sn), antimony (Sb), platinum (Pt), gold (Au), silver (Ag), lead (Pb) and bismuth (Bi) Preferably it is produced.

In the manufacturing method (1), (2) of the EUV mask blank of the present invention, the sputtering film is mainly composed of tantalum (Ta), and contains hafnium (Hf), silicon (Si), zirconium (Zr), germanium ( Ge), boron (B), nitrogen (N) and at least one element selected from hydrogen (H),
Ions implanted into the sputtering film are nickel (Ni), copper (Cu), zinc (Zn), palladium (Pd), indium (In), tin (Sn), antimony (Sb), platinum (Pt), It is preferably generated from at least one element selected from the group consisting of gold (Au), silver (Ag), lead (Pb) and bismuth (Bi).

In the manufacturing method (1), (2) of the EUV mask blank of the present invention, the sputtering film contains tantalum (Ta) and nitrogen (N), the Ta content is 40 to 80 at%, and N The content of is 20 to 60 at%,
The ions implanted into the sputtering film are preferably silver ions (Ag ⁺ ) generated from silver (Ag).

In the EUV mask blank manufacturing methods (1) and (2) of the present invention, the sputtering film is at least one selected from tantalum (Ta) and nitrogen (N), hydrogen (H) and boron (B). Elements, and
The total content of tantalum (Ta) and nitrogen (N) in the sputtering film is 80 to 99.9 at%, and the total content of at least one element selected from hydrogen (H) and boron (B) is 0.1 to 20 at%,
The ions implanted into the sputtering film are preferably silver ions (Ag ⁺ ) generated from silver (Ag).

In the EUV mask blank manufacturing methods (1) and (2) of the present invention, the number of times ions are implanted into the sputtering film may be one.
In the EUV mask blank manufacturing methods (1) and (2) of the present invention, the number of times ions are implanted into the sputtering film may be two or more.

In the EUV mask blank manufacturing methods (1) and (2) of the present invention, the total amount of silver ions implanted is preferably 1 × 10 ¹⁴ / cm ^{2 to} 5 × 10 ¹⁷ / cm ² .

In the EUV mask blank manufacturing methods (1) and (2) of the present invention, a low reflection layer for the inspection light of the mask pattern may be formed on the absorption layer.
In this case, after forming the sputtering formation film, a low reflection layer for the inspection light of the mask pattern may be formed on the sputtering formation film, and the ions may be implanted into the sputtering formation film from the low reflection layer side. .
Alternatively, the low reflection layer may be formed on the sputtering formation film after the sputtering formation film is formed and ions are implanted into the sputtering formation film.

  According to the present invention, since the EUV reflectance of the sputtering film can be adjusted by ion implantation, it is possible to reduce the thickness of the absorption layer while satisfying other required characteristics for the absorption layer of the EUV mask blank.

FIG. 1 is a schematic cross-sectional view showing an embodiment of an EUV mask blank manufactured by the method of the present invention. FIG. 2 is a view similar to FIG. However, a low reflection layer is formed on the absorption layer. FIG. 3 is a graph showing the relationship between the thickness of the absorption layer in Example 1, the EUV reflectance on the surface of the absorption layer, and the change rate of the EUV reflectance before and after ion implantation. FIG. 4 is a graph obtained by enlarging the range in which the film thickness of the absorption layer is 30 to 70 nm in FIG. FIG. 5 is a graph showing the relationship between the total film thickness of the absorption layer and the low reflection layer in Example 2, the EUV reflectance on the surface of the low reflection layer, and the change rate of the EUV reflectance before and after ion implantation. is there.

The present invention will be described below with reference to the drawings.
FIG. 1 is a schematic cross-sectional view showing an embodiment of a reflective mask blank for EUVL (hereinafter referred to as “the EUV mask blank of the present invention”) manufactured by the method of the present invention. In the EUV mask blank 1 shown in FIG. 1, a reflective layer 12 that reflects EUV light and an absorption layer 14 that absorbs EUV light are formed on a substrate 11 in this order. A protective layer 13 for protecting the reflective layer 12 is formed between the reflective layer 12 and the absorbent layer 14 when a pattern is formed on the absorbent layer 14.
In the EUV mask blank of the present invention, only the substrate 11, the reflective layer 12, and the absorption layer 14 are essential in the configuration shown in FIG. 1, and the protective layer 13 is an optional component.
Hereinafter, individual components of the EUV mask blank 1 will be described.

The substrate 11 is required to satisfy the characteristics as a substrate for an EUV mask blank.
Therefore, the substrate 11 preferably has a low thermal expansion coefficient (0 ± 1.0 × 10 ⁻⁷ / ° C., more preferably 0 ± 0.3 × 10 ⁻⁷ / ° C., further preferably 0 ± 0.2 × 10 ^{− 7} / ° C., more preferably 0 ± 0.1 × 10 ⁻⁷ / ° C., particularly preferably 0 ± 0.05 × 10 ⁻⁷ / ° C.), smoothness, flatness, and mask blank or pattern formation Those having excellent resistance to the cleaning liquid used for the subsequent cleaning of the photomask and the like are preferable. As the substrate 11, specifically, glass having a low thermal expansion coefficient, for example, SiO ₂ —TiO ₂ glass or the like is used, but is not limited thereto, and crystallized glass, quartz glass, or silicon on which β quartz solid solution is precipitated is used. A substrate made of metal or metal can also be used. A film such as a stress correction film may be formed on the substrate 11.
It is preferable that the substrate 11 has a smooth surface of 0.15 nm rms or less and a flatness of 100 nm or less because a high reflectivity and high transfer accuracy can be obtained in a photomask after pattern formation.
The size, thickness, etc. of the substrate 11 are appropriately determined according to the design value of the mask. In the examples described later, SiO ₂ —TiO ₂ glass having an outer shape of 6 inches (152.4 mm) square and a thickness of 0.25 inches (6.3 mm) was used.
It is preferable that no defects exist on the film-forming surface of the substrate 11, that is, the surface on the side where the reflective layer (multilayer reflective film) 12 is formed. However, even if it exists, the depth of the concave defect and the height of the convex defect are not more than 2 nm so that the phase defect does not occur due to the concave defect and / or the convex defect. The half width of the defect and the convex defect is preferably 60 nm or less.

  The characteristic particularly required for the reflective layer 12 of the EUV mask blank is a high EUV reflectance. Specifically, the maximum value of the light reflectance near a wavelength of 13.5 nm when a light ray in the wavelength region of EUV light is irradiated onto the surface of the reflective layer 12 at an incident angle of 6 degrees is preferably 60% or more, and 63% The above is more preferable, and 65% or more is more preferable. Even when the protective layer 13 is provided on the reflective layer 12, the maximum value of the light reflectance near the wavelength of 13.5 nm is preferably 60% or more, more preferably 63% or more, and 65% or more. Is more preferable.

As the reflective layer of the EUV mask blank, since a high EUV reflectance can be achieved, a low refractive index layer having a low refractive index with respect to EUV light and a high refractive index layer having a high refractive index with respect to EUV light are provided. A multilayer reflective film in which a plurality of layers are alternately laminated is widely used. The EUV mask blank of the present invention uses a Mo / Si multilayer reflective film in which a Mo layer as a low refractive index layer and a Si layer as a high refractive index layer are alternately laminated a plurality of times.
In this specification, the Mo / Si multilayer reflective film includes both the case where the uppermost layer is an Si layer and the case where the uppermost layer is an Mo layer. However, when comparing the case where the uppermost layer is the Si layer and the case where the uppermost layer is the Mo layer, the case where the uppermost layer is the Si layer is more stable against oxidation at room temperature in the atmosphere. From the viewpoint of preventing oxidation of the multilayer reflective film surface.
In the case of a Mo / Si multilayer reflective film, in order to obtain the reflective layer 12 having a maximum EUV reflectance of 60% or more, a Mo layer with a film thickness of 2.3 ± 0.1 nm and a film thickness of 4.5 ± 0 are used. A 1 nm Si layer may be laminated so that the number of repeating units is 30 to 60.

In addition, what is necessary is just to form each layer which comprises a Mo / Si multilayer reflective film so that it may become desired thickness using well-known film-forming methods, such as a magnetron sputtering method and an ion beam sputtering method. For example, when forming a Mo / Si multilayer reflective film using ion beam sputtering, a Mo target is used as a target, and Ar gas (gas pressure 1.3 × 10 ⁻² Pa to 2.7 × 10 ⁻ is used as a sputtering gas. ² Pa), an Mo layer is formed to have a thickness of 2.3 nm at an ion acceleration voltage of 300 to 1500 V and a film formation rate of 0.03 to 0.30 nm / sec. using a target, using an Ar gas as a sputtering gas (gas pressure ^{1.3 × 10 -2 Pa~2.7 × 10 -2} Pa), an ion acceleration voltage 300 to 1,500 V, the deposition rate of 0.03 to 0 It is preferable to form the Si layer so that the thickness is 4.5 nm at 30 nm / sec. With this as one period, a Mo / Si multilayer reflective film is formed by laminating the Mo layer and the Si layer for 30 to 60 periods.

  The protective layer 13 is an optional component provided for the purpose of protecting the reflective layer 12 so that the reflective layer 12 is not damaged by the etching process when the absorption layer 14 is patterned by an etching process, usually a dry etching process. It is. However, from the viewpoint of protecting the reflective layer 12, it is preferable to form the protective layer 13 on the reflective layer 12.

As the material of the protective layer 13, a material that is not easily affected by the etching process of the absorbing layer 14, that is, the etching rate is slower than that of the absorbing layer 14 and is not easily damaged by the etching process is selected.
In addition, the protective layer 13 may be selected from a material having a high EUV reflectance so that the EUV reflectance of the reflective layer 12 is not impaired even after the protective layer 13 is formed. preferable.
As the protective layer 13, a platinum group metal layer such as ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir), platinum (Pt), or a compound containing these metals A layer is preferred because it satisfies the above conditions. Among them, it is preferable to form a Ru layer or a Ru compound (RuB or the like) layer. When a Ru layer or a Ru compound layer is formed as the protective layer 13, the content of Ru in the protective layer 13 is preferably 50 at% or more, more preferably 70 at% or more, and even more preferably 90 at% or more. 95 at% or more is preferable.

When the protective layer 13 is formed on the reflective layer 12, the surface roughness of the surface of the protective layer 13 is preferably 0.5 nm rms or less. In addition, in this specification, surface roughness is demonstrated as the root mean square roughness Rq (old RMS) based on JIS-B0601. When the surface roughness of the surface of the protective layer 13 is large, the surface roughness of the absorbing layer 14 formed on the protective layer 13 increases, the edge roughness of the pattern formed on the absorbing layer 14 increases, Dimensional accuracy deteriorates. Since the influence of edge roughness becomes more prominent as the pattern becomes finer, the surface of the absorption layer 14 is required to be smooth.
If the surface roughness of the surface of the protective layer 13 is 0.5 nm rms or less, the surface of the absorption layer 14 formed on the protective layer 13 is sufficiently smooth, so that the dimensional accuracy of the pattern deteriorates due to the influence of edge roughness. There is no fear. The surface roughness of the surface of the protective layer 13 is more preferably 0.4 nm rms or less, and further preferably 0.3 nm rms or less.

  When the protective layer 13 is formed on the reflective layer 12, the thickness of the protective layer 13 is preferably 1 to 10 nm because the EUV reflectance can be increased and the etching resistance can be obtained. The thickness of the protective layer 13 is more preferably 1 to 5 nm, and further preferably 2 to 4 nm.

When the protective layer 13 is formed on the reflective layer 12, the protective layer 13 can be formed using a known film forming method such as a magnetron sputtering method or an ion beam sputtering method.
When a Ru layer is formed as the protective layer 13 using an ion beam sputtering method, a Ru target may be used as a target and discharged in an argon (Ar) atmosphere. Specifically, ion beam sputtering may be performed under the following conditions.
Sputtering Gas: Ar (gas ^{pressure: 1.3 × 10 -2 Pa~2.7 × 10} -2 Pa)
Ion acceleration voltage: 300-1500V
Deposition rate: 1.8-18.0 nm / min

  The characteristic particularly required for the absorption layer 14 is that the EUV reflectance is extremely low. Specifically, when the surface of the absorbing layer 14 is irradiated with light in the wavelength region of EUV light, the maximum light reflectance near a wavelength of 13.5 nm is preferably 0.5% or less, more preferably 0.1% or less. preferable.

In order to achieve the above characteristics, the absorption layer 14 is made of a material having a high EUV light absorption coefficient, specifically, a material mainly containing tantalum (Ta), a material mainly containing palladium (Pd), chromium, and the like. It is preferably made of any material selected from a material mainly composed of (Cr) and a material mainly composed of ruthenium (Ru). In this specification, the phrase “a material containing the element X as a main component” means a material containing the element X in an amount of 40 at% or more, preferably 50 at% or more, more preferably 55 at% or more. .
In the present invention, using these materials, a sputtering formation film that becomes a precursor of the absorption layer is formed by a sputtering method.

As a constituent material of the sputtering film, a material containing Ta as a main component is preferable because it is chemically stable and etching is easy when forming the pattern of the absorption layer.
As a material mainly composed of Ta, in addition to Ta, at least one element selected from hafnium (Hf), silicon (Si), zirconium (Zr), germanium (Ge), boron (B), and nitrogen (N) is used. The material to include is mentioned. Specific examples of the material containing the above elements other than Ta include TaN, TaHf, TaHfN, TaBSi, TaBSiN, TaB, TaBN, TaSi, TaSiN, TaGe, TaGeN, TaZr, TaZrN, and the like.

Further, as described above, when the surface roughness of the surface of the absorption layer 14 is large, the edge roughness of the pattern formed on the absorption layer 14 increases, and the dimensional accuracy of the pattern deteriorates. Since the influence of edge roughness becomes more prominent as the pattern becomes finer, the surface of the absorption layer 14 is required to be smooth.
For this reason, a film containing Ta and N (TaN film) is preferable as the sputtering formation film serving as the precursor of the absorption layer 14 in that a film having an amorphous crystal state can be easily formed. A film having an amorphous crystal state is excellent in surface smoothness.
When the sputtering film is a TaN film, the Ta content is preferably 40 to 80 at%, the N content is preferably 20 to 60 at%, the Ta content is 40 to 70 at%, and the N content is 30 to 60 at%. % Is more preferable.
The sputtering film may contain at least one element selected from H and B in addition to Ta and N. In this case, the total content of Ta and N is preferably 80 to 99.9 at%, the total content of at least one element selected from H and B is preferably 0.1 to 20 at%, and the total content of Ta and N is The total content of 90 to 99.9 at% and at least one element selected from H and B is more preferably 0.1 to 10 at%.

Further, the thickness of the sputtering formed film serving as the precursor of the absorption layer 14 is preferably in the range of 20 to 100 nm because high transfer accuracy can be obtained, and more preferably in the range of 20 to 90 nm.
In addition, since the thickness of the sputtering formed film hardly changes by ion implantation described later, the thickness of the sputtering formed film becomes the thickness of the absorption layer 14 after ion implantation.

Various sputtering methods such as a magnetron sputtering method and an ion beam sputtering method can be appropriately selected depending on the composition of the film to be formed for the formation of the sputtering formation film serving as the precursor of the absorption layer 14.
When a TaN film is formed using a magnetron sputtering method as the sputtering formation film, the TaN film can be formed by using a Ta target and discharging the target in a nitrogen (N ₂ ) atmosphere diluted with Ar.
In order to form the TaN film as the sputtering film by the above exemplified method, specifically, the following film formation conditions may be used.
Sputtering gas: Mixed gas of Ar and N ₂ (N ₂ gas concentration: 3 to 80 vol%, preferably 5 to 30 vol%, more preferably 8 to 15 vol%. Gas pressure: 0.5 × 10 ⁻¹ Pa to 10 × 10 ^-1 Pa, preferably ^{0.5 × 10 -1 Pa~5 × 10 -1} Pa, more preferably ^{0.5 × 10 -1 Pa~3 × 10 -1} Pa.)
Input power: 30 to 1000 W, preferably 50 to 750 W, more preferably 80 to 500 W
Deposition rate: 2.0-60 nm / min, preferably 3.5-45 nm / min, more preferably 5-30 nm / min
In order to form a TaNH film as a sputtering film, specifically, the following film formation conditions may be used.
Sputtering gas: Ar, N ₂ and H ₂ mixed gas (H ₂ gas concentration: 1-50 vol%, preferably 1-30 vol%, N ₂ gas concentration: 1-80 vol%, preferably 5-75 vol%, Ar gas concentration 5~95vol%, preferably 10~94vol%, gas ^{pressure: 1.0 × 10 -1 Pa~50 × 10} -1 Pa, preferably ^{1.0 × 10 -1 Pa~40 × 10 -1} Pa, more preferably ^{1.0 × 10 -1 Pa~30 × 10 -1} Pa.)
Input power: 30 to 1000 W, preferably 50 to 750 W, more preferably 80 to 500 W
Deposition rate: 0.5-60 nm / min, preferably 1.0-45 nm / min, more preferably 1.5-30 nm / min

In the method of the present invention, by implanting ions of an element having a higher extinction coefficient with respect to EUV light into the sputtering formation film serving as a precursor of the absorption layer 14, than the absorption coefficient with respect to EUV light before ion implantation, The absorption layer 14 having a high absorption coefficient for EUV light after ion implantation can be realized.
Therefore, ions to be implanted are required to be generated from an element having a higher extinction coefficient with respect to EUV light than the elements constituting the sputtering film. As described above, the constituent material of the sputtering formation film is a material mainly composed of tantalum (Ta), a material mainly composed of palladium (Pd), a material mainly composed of chromium (Cr), or ruthenium ( Since materials having Ru as a main component are preferable, ions generated from elements having a higher extinction coefficient with respect to EUV light than elements that are the main components of these materials, that is, Ta, Pd, Cr, and Ru are used. . Specifically, ions generated from at least one of the elements included in Groups 10 to 15 of the periodic table are used. More specifically, nickel (Ni), copper (Cu), zinc (Zn), palladium (Pd), indium (In), tin (Sn), antimony (Sb), platinum (Pt), gold (Au) , Ions generated from at least one element selected from the group consisting of silver (Ag), lead (Pb), and bismuth (Bi) are used. Among these, silver ions (Ag ⁺ ) generated from Ag are preferable because they have the largest extinction coefficient and are advantageous for thinning the absorption layer 14.

In the method of the present invention, the sputtering formation film is ion-implanted so that the absorption coefficient for EUV light is higher than that before ion implantation. After the formation of the film to be the absorption layer 14 (that is, the sputtering formation film), The purpose is to change the EUV reflectivity. When the absorption coefficient for EUV light is made higher than that before ion implantation, the EUV reflectance becomes lower. For this reason, the EUV reflectance can be adjusted after the film to be the absorption layer 14 (that is, the sputtering film) is formed by selecting the element to be ion-implanted and adjusting the ion implantation amount.
Thereby, it is considered that the absorption layer can be made thin while satisfying other required characteristics for the absorption layer 14.

In the method of the present invention, it is preferable that the change in EUV reflectance before and after ion implantation satisfies the following.
When the reflectance at the center wavelength (wavelength 13.5 nm) in the EUV wavelength region on the surface of the sputtering film is R _i before ion implantation and R _f after ion implantation, the rate of change in reflectance before and after ion implantation ( The value of (R _f −R _i ) × 100 / R _i ) is preferably −5% or less, more preferably −10% or less, further preferably −15% or less, and further preferably −20% or less.

In order to achieve the change in the EUV reflectance before and after the ion implantation, it is preferable that the change in the extinction coefficient before and after the ion implantation satisfies the following.
Regarding the extinction coefficient of the sputtering film at the central wavelength (wavelength 13.5 nm) in the EUV wavelength region, when the ion pre-ion implantation is k _i and the ion implantation (that is, the absorption layer 14) is k _f , the value of the extinction coefficient of the rate of change before and after injection _{((k f -k i) /} k i) is preferably 0.03 or more, more preferably 0.05 or more, more preferably 0.07 or more, 0. 10 or more is particularly preferable.

However, it should be noted that other optical characteristics of the sputtering formed film also change before and after ion implantation. For example, the refractive index in the EUV wavelength region changes before and after ion implantation. When the refractive index in the EUV wavelength region changes greatly, the oscillation period of the reflectance change with respect to the change in the thickness of the absorption layer 14 changes, and it becomes difficult to obtain a desired reflectance characteristic with a desired thickness. is there.
In the method of the present invention, it is preferable that the change in the refractive index in the EUV wavelength region before and after ion implantation satisfies the following.
When the refractive index of the sputtering film at the center wavelength (wavelength 13.5 nm) in the EUV wavelength region is n _i before ion implantation and n _f after ion implantation (that is, absorption layer 14) is ion implantation. It is preferable that the amount of change in refractive index before and after (n _f −n _i ) satisfies the following formula.
−0.1 ≦ n _f −n _i ≦ 0.1

In the method of the present invention, when silver ions (Ag ⁺ ) are implanted into the sputtering film, a total implantation amount of 1 × 10 ¹⁴ / cm ^{2 to} 5 × 10 ¹⁷ / cm ² increases the rate of change of the extinction coefficient. It is preferable for reasons such as being possible.
The total implantation amount of silver ions (Ag ⁺ ) is more preferably 5 × 10 ¹⁴ / cm ^{2 to} 5 × 10 ¹⁷ / cm ² , more preferably 1 × 10 ¹⁵ / cm ^{2 to} 5 × 10 ¹⁷ / cm ² , In the method of the present invention, when ions other than silver ions (Ag ⁺ ) are implanted, the total implantation amount is appropriately selected according to the type of the ions.

In the method of the present invention, the number of times of ion implantation into the sputtering film is not particularly limited, and the total implantation amount may be implanted by one ion implantation or may be implanted in two or more times. .
As will be described later, when a low reflection layer for the inspection light of the mask pattern is formed on the absorption layer, ions are implanted into the sputtering formation film to form the low reflection layer after using the sputtering formation film as the absorption layer. Alternatively, after forming a low reflection layer on the sputtering formation film, ions may be implanted into the sputtering formation film from the low reflection layer side, and the sputtering formation film may be used as an absorption layer. In addition, it has been confirmed by an example described later that ions can be implanted into the sputtering film even in the latter procedure.

The EUV mask blank of the present invention may have components other than the configuration shown in FIG. 1 (that is, the substrate 11, the reflective layer 12, the protective layer 13, and the absorption layer 14).
FIG. 2 is a schematic cross-sectional view showing another embodiment of the EUV mask blank of the present invention.
In the EUV mask blank 1 ′ shown in FIG. 2, a low reflection layer 15 for inspection light used for inspection of a mask pattern is formed on the absorption layer 14.

When producing an EUV mask from the EUV mask blank of the present invention, after forming a pattern on the absorption layer, it is inspected whether this pattern is formed as designed. In the inspection of the mask pattern, an inspection machine that normally uses 257 nm light as inspection light is used. That is, the difference in reflectance of light of about 257 nm, specifically, the reflection between the surface exposed by removing the absorption layer 14 by pattern formation and the surface of the absorption layer 14 remaining without removal by pattern formation. Inspected by rate difference. Here, the former is the surface of the protective layer 13 and the surface of the reflective layer 12 when the protective layer 13 is not formed on the reflective layer 12.
Therefore, if the difference in reflectance between the surface of the protective layer 13 (or the surface of the reflective layer 12) and the surface of the absorption layer 14 with respect to the wavelength of the inspection light of about 257 nm is too small, the contrast at the time of inspection deteriorates and accurate inspection cannot be performed. There is.
Hereinafter, when the inspection light is referred to in this specification, the light having a wavelength of 257 nm is indicated unless the wavelength is particularly described.

The absorption layer 14 in which ions of an element having a higher extinction coefficient with respect to EUV light are implanted into the above-described absorption layer 14, that is, the sputtering formation film having the above-described configuration, has an extremely low EUV reflectance, and the absorption layer of the EUV mask blank. However, when viewed with respect to the wavelength of the inspection light, it cannot be said that the light reflectance is sufficiently low. As a result, the difference between the reflectance on the surface of the absorption layer 14 at the wavelength of the inspection light and the reflectance on the surface of the reflective layer 12 (or the surface of the protective layer 13) becomes small, and there is a possibility that sufficient contrast during inspection cannot be obtained. . If sufficient contrast at the time of inspection is not obtained, pattern defects may not be sufficiently determined in mask inspection, and accurate defect inspection may not be performed.
As in the EUV mask blank 1 ′ shown in FIG. 2, the low reflection layer 15 is formed on the absorption layer 14, so that the contrast at the time of inspection becomes good. In other words, the light reflectance at the wavelength of the inspection light is extremely low. For the low reflection layer 15 formed for such a purpose, the maximum light reflectance of the wavelength of the inspection light when irradiated with light in the wavelength region (near 257 nm) of the inspection light is preferably 15% or less, and 10% The following is more preferable, and 5% or less is more preferable.
If the light reflectance at the wavelength of the inspection light in the low reflection layer 15 is 15% or less, the contrast at the time of the inspection is good. Specifically, the contrast between the reflected light having the wavelength of the inspection light on the surface of the protective layer 13 (or the surface of the reflective layer 12) and the reflected light having the wavelength of the inspection light on the surface of the low reflective layer 15 is 40% or more. .

In this specification, the contrast is obtained using the following equation.
Contrast (%) = ((R ₂ −R ₁ ) / (R ₂ + R ₁ )) × 100
Here, R _{2 at} the wavelength of the inspection light is the reflectance at the surface of the protective layer 13 (or the surface of the reflective layer 12), and R ₁ is the reflectance at the surface of the low reflective layer 15. Note that R ₁ and R ₂ are measured in a state in which a pattern is formed on the absorption layer 14 and the low reflection layer 15 of the EUV mask blank 1 ′ shown in FIG. The R ₂ is a value measured on the surface of the protective layer 13 (or the surface of the reflective layer 12) exposed to the outside after the absorption layer 14 and the low reflective layer 15 are removed by pattern formation, and R ₁ is removed by the pattern formation. This is a value measured on the surface of the remaining low reflection layer 15.
In the present invention, the contrast represented by the above formula is more preferably 45% or more, further preferably 60% or more, and particularly preferably 70% or more.

In order to achieve the above characteristics, the low reflection layer 15 is made of a material whose refractive index at the wavelength of the inspection light is lower than that of the absorption layer 14, and the crystalline state is preferably amorphous.
Specific examples of such a low reflection layer 15 include those containing Ta, oxygen (O) and nitrogen (N) in the ratios described below (low reflection layer (TaON)).
Ta content 20 to 80 at%, preferably 20 to 70 at%, more preferably 20 to 60 at%
Total content of O and N 20-80 at%, preferably 30-80 at%, more preferably 40-80 at%
Composition of O and N (O: N) 20: 1 to 1:20, preferably 18: 1 to 1:18, more preferably 15: 1 to 1:15

The low reflective layer (TaON) has an amorphous crystal state and a smooth surface because of the above configuration. Specifically, the surface roughness of the surface of the low reflection layer (TaON) is 0.5 nm rms or less.
As described above, the surface of the absorption layer 14 is required to be smooth in order to prevent deterioration of the dimensional accuracy of the pattern due to the influence of edge roughness. Since the low reflection layer 15 is formed on the absorption layer 14, the surface thereof is required to be smooth for the same reason.
If the surface roughness of the surface of the low reflection layer 15 is 0.5 nm rms or less, the surface of the low reflection layer 15 is sufficiently smooth, so that the dimensional accuracy of the pattern does not deteriorate due to the influence of edge roughness. The surface roughness of the surface of the low reflective layer 15 is more preferably 0.4 nm rms or less, and further preferably 0.3 nm rms or less.

  When the low reflection layer 15 is formed on the absorption layer 14, the total thickness of the absorption layer 14 and the low reflection layer 15 is preferably 25 to 130 nm. Further, if the thickness of the low reflection layer 15 is larger than the thickness of the absorption layer 14, the EUV light absorption characteristics in the absorption layer 14 may be deteriorated. Therefore, the thickness of the low reflection layer 15 is the thickness of the absorption layer 14. It is preferable to be smaller than this. For this reason, 5-30 nm is preferable and, as for the thickness of the low reflection layer 15, 10-20 nm is more preferable.

The low reflection layer (TaON) having the above-described configuration is formed by oxygen diluted with an inert gas containing at least one of helium (He), argon (Ar), neon (Ne), krypton (Kr), and xenon (Xe) ( It can be formed by sputtering using a Ta target, for example, magnetron sputtering or ion beam sputtering, in an O ₂ ) and nitrogen (N ₂ ) atmosphere. Alternatively, the Ta target is discharged in a nitrogen (N ₂ ) atmosphere diluted with an inert gas containing at least one of helium (He), argon (Ar), neon (Ne), krypton (Kr), and xenon (Xe). After forming a film containing Ta and N, the low reflection of the above structure is obtained by oxidizing the formed film by, for example, exposing it to oxygen plasma or irradiating an ion beam using oxygen. It is good also as a layer (TaON).

In order to form the low reflection layer (TaON) by the above-described method, specifically, the following film formation conditions may be used.
Sputtering gas: Ar, O ₂ and N ₂ mixed gas (O ₂ gas concentration: 5 to 80 vol%, N ₂ gas concentration: 5 to 75 vol%, preferably O ₂ gas concentration: 6 to 70 vol%, N ₂ gas concentration : 6~35vol%, more preferably O ₂ gas concentration: 10~30vol%, N ₂ gas concentration: 10 to 30 vol% .Ar gas concentration: 5~90vol%, preferably 10~88vol%, more preferably 20 80 vol%, gas ^{pressure: 1.0 × 10 -1 Pa~50 × 10} -1 Pa, preferably ^{1.0 × 10 -1 Pa~40 × 10 -1} Pa, more preferably 1.0 × 10 ^-1 Pa-30 × 10 ⁻¹ Pa.)
Input power: 30 to 1000 W, preferably 50 to 750 W, more preferably 80 to 500 W
Deposition rate: 0.1 to 50 nm / min, preferably 0.2 to 45 nm / min, more preferably 0.2 to 30 nm / min
When an inert gas other than Ar is used, the concentration of the inert gas is set to the same concentration range as the Ar gas concentration described above. Further, when a plurality of types of inert gases are used, the total concentration of the inert gases is set to the same concentration range as the Ar gas concentration described above.

  The low reflective layer 15 may further contain hydrogen (H). In this case, it becomes a TaONH film. When the low reflective layer 15 is a TaONH film, the H content is more preferably 1 to 15 at%, further preferably 5 to 15 at%, and particularly preferably 5 to 10 at%. Further, the total content of Ta, O and N is more preferably 85 to 99 at%, further preferably 85 to 95 at%, and particularly preferably 90 to 95 at%. The composition ratio of Ta and (O + N) is preferably 1: 7 to 2: 1, more preferably 1: 6 to 1: 1, and particularly preferably 1: 5 to 1: 1.

  The low reflection layer 15 (TaONH film) having the above-described configuration includes an inert gas containing at least one of helium (He), argon (Ar), neon (Ne), krypton (Kr), and xenon (Xe), oxygen, It can be formed by performing a sputtering method using a Ta target, for example, a magnetron sputtering method or an ion beam sputtering method in an atmosphere containing (O), nitrogen (N) and hydrogen (H).

In order to form the low reflective layer 15 (TaONH) by the above-described method, specifically, the following film formation conditions may be used.
Sputtering gas: Ar, O ₂ , N ₂ and H ₂ mixed gas (H ₂ gas concentration: 1 to 50 vol%, preferably 1 to 30 vol%, O ₂ gas concentration: 1 to 80 vol%, preferably 5 to 75 vol% N ₂ gas concentration: 1 to 80 vol%, preferably 5 to 75 vol%, Ar gas concentration: 5 to 95 vol%, preferably 10 to 89 vol%, gas pressure: 1.0 × 10 ⁻¹ Pa to 50 × 10 ^{− 1} Pa, preferably ^{1.0 × 10 -1 Pa~40 × 10 -1} Pa, more preferably ^{1.0 × 10 -1 Pa~30 × 10 -1} Pa.)
Input power: 30 to 1000 W, preferably 50 to 750 W, more preferably 80 to 500 W
Deposition rate: 0.01 to 60 nm / min, preferably 0.05 to 45 nm / min, more preferably 0.1 to 30 nm / min
When an inert gas other than Ar is used, the concentration of the inert gas is set to the same concentration range as the Ar gas concentration described above. Further, when a plurality of types of inert gases are used, the total concentration of the inert gases is set to the same concentration range as the Ar gas concentration described above.

  As described above, the configuration in which the low reflection layer 15 is formed on the absorption layer 14 like the EUV mask blank 1 ′ shown in FIG. 2 is preferable because the wavelength of the inspection light for the pattern is different from the wavelength of the EUV light. It is. Therefore, when EUV light (around 13.5 nm) is used as the pattern inspection light, it is considered unnecessary to form the low reflection layer 15 on the absorption layer 14. The wavelength of the inspection light tends to shift to the short wavelength side as the pattern size becomes smaller, and it is conceivable that it will shift to 193 nm and further to 13.5 nm in the future. In addition, when the wavelength of the inspection light is 193 nm, it may not be necessary to form the low reflection layer 15 on the absorption layer 14. Furthermore, when the wavelength of the inspection light is 13.5 nm, it is considered unnecessary to form the low reflection layer 15 on the absorption layer 14.

The EUV mask blank of the present invention may have a functional film known in the field of EUV mask blanks in addition to the reflective layer 12, the protective layer 13, the absorbing layer 14, and the low reflective layer 15. As a specific example of such a functional film, for example, as described in JP-A-2003-501823, there is a high dielectric coating applied to the back side of the substrate in order to promote electrostatic chucking of the substrate. Can be mentioned. Here, the back surface of the substrate refers to the surface of the substrate 11 in FIG. 1 opposite to the side on which the reflective layer 12 is formed. For the high dielectric coating applied to the back surface of the substrate for such a purpose, the electrical conductivity and thickness of the constituent material are selected so that the sheet resistance is 100Ω / □ or less. The constituent material of the high dielectric coating can be widely selected from those described in known literature. For example, a high dielectric constant coating described in JP-A-2003-501823, specifically, a coating made of silicon, TiN, molybdenum, chromium, and TaSi can be applied. The thickness of the high dielectric coating is, for example, 10 to 1000 nm.
The high dielectric coating can be formed using a known film forming method, for example, a sputtering method such as a magnetron sputtering method or an ion beam sputtering method, a CVD method, a vacuum evaporation method, or an electrolytic plating method.

The present invention will be further described below using examples.
(Example 1)
In this example, the EUV mask blank shown in FIG. 1 is produced.
As the substrate 11 for film formation, a SiO ₂ —TiO ₂ glass substrate (outer diameter 6 inches (152.4 mm) square, thickness 6.3 mm) is used. The glass substrate has a thermal expansion coefficient of 0.05 × 10 ⁻⁷ / ° C., a Young's modulus of 67 GPa, a Poisson's ratio of 0.17, and a specific rigidity of 3.07 × 10 ⁷ m ² / s ² . This glass substrate is polished to form a smooth surface with a surface roughness rms of 0.15 nm or less and a flatness of 100 nm or less.

A conductive film (not shown) having a sheet resistance of 100Ω / □ is applied to the back side of the substrate 11 by depositing a Cr film having a thickness of 100 nm using a magnetron sputtering method.
A substrate 11 (outer diameter 6 inches (152 mm) square, thickness 6.3 mm) is fixed to a flat electrostatic chuck having a flat plate shape by using the formed Cr film, and ion beam sputtering is performed on the surface of the substrate 11. The Mo / Si multilayer reflective film (reflective layer 12) having a total film thickness of 272 nm ((4.5 nm + 2.3 nm) × 40) is obtained by repeating 40 cycles of alternately forming the Si layer and the Mo layer using the method. Form.
Further, the protective layer 13 is formed on the Mo / Si multilayer reflective film (reflective layer 12) by forming a Ru layer (thickness: 2.5 nm) using an ion beam sputtering method.

The film forming conditions for the Si film, the Mo layer, and the Ru layer are as follows.
Conditions for forming the Si layer Target: Si target (boron doped)
Sputtering gas: Ar gas (gas pressure 0.02 Pa)
Voltage: 700V
Deposition rate: 0.077 nm / sec
Film thickness: 4.5nm
Conditions for forming the Mo layer Target: Mo target Sputtering gas: Ar gas (gas pressure 0.02 Pa)
Voltage: 700V
Deposition rate: 0.064 nm / sec
Film thickness: 2.3 nm
Ru layer deposition conditions Target: Ru target Sputtering gas: Ar gas (gas pressure 0.02 Pa)
Voltage: 500V
Deposition rate: 0.023 nm / sec
Film thickness: 2.5nm

Next, a TaNH film is formed on the protective layer 13 as a sputtering formation film serving as a precursor of the absorption layer 14 by using a magnetron sputtering method.
The conditions for forming the TaNH film are as follows.
Deposition conditions <br/> Target TaNH film: Ta target Sputtering gas: mixed gas of Ar and N ₂ and _{H 2 (Ar: 89vol%,} N 2: 8.3vol%, H 2: 2.7vol%, gas (Pressure: 0.46 Pa)
Input power: 300W
Deposition rate: 1.5 nm / min
Film thickness: 32nm

Silver ions (Ag ⁺ ) are ion-implanted into the TaNH film formed by the above procedure under the following conditions.
Total injection amount: 1 × 10 ¹⁵ / cm ²
Acceleration voltage: Adjusted at 30-80 keV

For the TaNH film before and after ion implantation, the extinction coefficient and refractive index at the center wavelength (wavelength 13.5 nm) in the EUV wavelength region are measured by the following procedure. The film was formed on a 4-inch wafer under the same conditions as those described above, and evaluated by measuring the “angle dependence” of the reflectance in the 13.5 nm region. The EUV reflectance and the incident angle of EUV light, the extinction coefficient, and the refractive index are expressed by the following equations.
R = | (sin θ − ((n + ik) ² −cos ² θ) ^1/2 ) / (sin θ + ((n + ik) ² −cos ² θ) ^1/2 ) |
Here, θ is the EUV light incident angle, R is the EUV reflectivity at the incident angle θ, n is the refractive index of the sputtering film or absorption layer 14, and k is the extinction coefficient of the sputtering film or absorption layer 14. The optical constants (n and k) can be estimated by fitting reflectance measurements at each EUV incident angle using the above equation.
The extinction coefficient k _i before ion implantation is 0.0338, and the extinction coefficient k _f after ion implantation is 0.0377. The rate of change of extinction coefficient before and after ion implantation ((k _f −k _i ) / k _i ) is 0.12.
The refractive index n _i before ion implantation is 0.9437, and the refractive index n _f after ion implantation is 0.9444. The amount of change in refractive index (n _f −n _i ) before and after ion implantation is −0.007.

For the TaNH film before and after ion implantation, the reflectance at the center wavelength (wavelength 13.5 nm) in the EUV wavelength region is measured by the following procedure. The EUV mask blank (FIG. 1) produced by the above-described procedure is irradiated with EUV light on the surface of the TaNH film before and after ion implantation, and the EUV reflectance is measured.
The EUV reflectance R _i before ion implantation is 6.0%, and the EUV reflectance R _f after ion implantation is 4.5%. The change rate ((R _f −R _i ) × 100 / R _i ) of the EUV reflectance before and after ion implantation is −25.0%.

When the thickness of the TaNH film is changed in the range of 0 to 90 nm and the EUV reflectance (EUVR) before and after ion implantation and the rate of change of EUVR before and after ion implantation are evaluated, the relationship shown in FIG. 3 is obtained. Here, TaNH_Ag (none) represents the EUV reflectance before ion implantation, and TaNH_Ag (1e15) represents the EUV reflectance after ion implantation. When the film thickness of the TaNH film is 0 nm, it is the EUV reflectance of the surface of the Ru film as the protective layer 13. FIG. 4 is an enlarged graph of the TaNH film thickness range of 30 to 70 nm. From these graphs, it can be confirmed that the EUV reflectance can be lowered by the implantation of silver ions (Ag ⁺ ). It can also be confirmed that the same EUV reflectance can be achieved with a smaller film thickness by the implantation of silver ions (Ag ⁺ ).

(Example 2)
In this example, the TaNHH film is formed as the low reflection layer 15 by using the magnetron sputtering method after changing the film thickness in the range of 0 to 90 nm and forming the TaNH film in the same procedure as in Example 1.
The conditions for forming the TaONH film are as follows.
Deposition conditions <br/> Target TaONH film: Ta target Sputtering gas: mixed gas of Ar and O ₂ and N ₂ and _{H 2 (Ar: 48vol%,} O 2: 36vol%, N 2: 14vol%, H 2 : 2 vol%, gas pressure: 0.3 Pa)
Input power: 450W
Deposition rate: 1.5 nm / min
Film thickness: 7nm

Silver ions (Ag ⁺ ) are implanted from the side of the TaONH film formed by the above procedure by the same procedure as in Example 1 (total implantation amount: 1 × 10 ¹⁵ / cm ² ). When the EUV reflectance (EUVR) before and after ion implantation and the rate of change of EUVR before and after ion implantation are evaluated, the relationship shown in FIG. 5 is obtained. Here, TaNH_Ag (none) represents the EUV reflectance before ion implantation, and TaNH_Ag (1e15) represents the EUV reflectance after ion implantation. When the total film thickness is 7 nm, the EUV reflectance is obtained when the TaONH film is formed on the Ru film as the protective layer 13 without forming the TaNH film. From this graph, it can be seen that, even when silver ions (Ag ⁺ ) are implanted from the side of the TaONH film formed as the low reflective layer, the ion implantation into the TaNH film can be performed as in the first embodiment. It can be confirmed from the rate result.

1, 1 ': EUV mask blank 11: Substrate 12: Reflective layer (Mo / Si multilayer reflective film)
13: Protection layer 14: Absorption layer 15: Low reflection layer

Claims (17)

A method of manufacturing a reflective mask blank for EUV lithography (EUVL), comprising: forming a reflective layer that reflects EUV light on a substrate; and forming an absorbing layer that absorbs EUV light on the reflective layer,
The absorption layer is formed by implanting ions of an element having a higher extinction coefficient with respect to EUV light than the sputtering formation film into a sputtering formation film formed by a sputtering method. A method for producing a reflective mask blank for EUVL, characterized in that the reflective mask blank is formed so as to have a high absorption coefficient for EUV light after implantation. For EUV lithography (EUVL), a reflective layer for reflecting EUV light is formed on a substrate, a protective layer for the reflective layer is formed on the reflective layer, and an absorbing layer for absorbing EUV light is formed on the protective layer. A method of manufacturing a reflective mask blank,
The absorption layer is formed by implanting ions of an element having a higher extinction coefficient with respect to EUV light than the sputtering formation film into a sputtering formation film formed by a sputtering method. A method for producing a reflective mask blank for EUVL, characterized in that the reflective mask blank is formed so as to have a high absorption coefficient for EUV light after implantation. When the reflectance of the central wavelength (wavelength 13.5 nm) of the EUV wavelength region on the surface of the sputtering film is R _i before ion implantation and R _f after ion implantation, the change in EUV reflectance before and after ion implantation. rate is _{((R f -R i) ×} 100 / R i) values less -5%, according to claim 1 or 2 EUVL reflective mask blank for manufacturing method according to. When the extinction coefficient of the sputtering film at the center wavelength (wavelength 13.5 nm) in the EUV wavelength region is k _i before ion implantation and k _f after ion implantation, the extinction coefficient before and after ion implantation is values of conversion _{((k f -k i) /} k i) is 0.03 or more, a manufacturing method of the reflective mask blank for EUVL according to any one of claims 1 to 3. The amount of change in the refractive index before and after ion implantation when the refractive index of the sputtering film at the center wavelength (wavelength 13.5 nm) in the EUV wavelength region is n _i before ion implantation and n _f after ion implantation. (n _f -n _i) satisfies the following formula, manufacturing method of the reflective mask blank for EUVL according to any one of claims 1 to 4.
−0.1 ≦ n _f −n _i ≦ 0.1   The sputtering film is a material mainly composed of tantalum (Ta), a material mainly composed of palladium (Pd), a material mainly composed of chromium (Cr), a material mainly composed of ruthenium (Ru), The manufacturing method of the reflective mask blank for EUVL in any one of Claims 1-5 which consist of either selected from these.   The reflective mask for EUVL according to any one of claims 1 to 6, wherein ions to be implanted into the sputtering film are generated from at least one element included in Groups 10 to 15 of the periodic table. Blank manufacturing method.   Ions implanted into the sputtering film are nickel (Ni), copper (Cu), zinc (Zn), palladium (Pd), indium (In), tin (Sn), antimony (Sb), platinum (Pt), The EUVL reflection according to claim 1, wherein the EUVL reflection is generated from at least one element selected from the group consisting of gold (Au), silver (Ag), lead (Pb), and bismuth (Bi). Mold mask blank manufacturing method. The sputtering formation film is mainly composed of tantalum (Ta) and is composed of hafnium (Hf), silicon (Si), zirconium (Zr), germanium (Ge), boron (B), nitrogen (N), and hydrogen (H). Including at least one element selected,
Ions implanted into the sputtering film are nickel (Ni), copper (Cu), zinc (Zn), palladium (Pd), indium (In), tin (Sn), antimony (Sb), platinum (Pt), The EUVL reflection according to claim 1, wherein the EUVL reflection is generated from at least one element selected from the group consisting of gold (Au), silver (Ag), lead (Pb), and bismuth (Bi). Mold mask blank manufacturing method. The sputtering film contains tantalum (Ta) and nitrogen (N), the Ta content is 40-80 at%, the N content is 20-60 at%,
The manufacturing method of the reflective mask blank for EUVL according to claim 9, wherein the ions implanted into the sputtering film are silver ions (Ag ⁺ ) generated from silver (Ag). The sputtering formation film contains tantalum (Ta) and nitrogen (N), and at least one element selected from hydrogen (H) and boron (B),
The total content of tantalum (Ta) and nitrogen (N) in the sputtering film is 80 to 99.9 at%, and the total content of at least one element selected from hydrogen (H) and boron (B) is 0.1 to 20 at%,
The manufacturing method of the reflective mask blank for EUVL according to claim 9, wherein the ions implanted into the sputtering film are silver ions (Ag ⁺ ) generated from silver (Ag).   The method for producing a reflective mask blank for EUVL according to any one of claims 1 to 11, wherein the number of times ions are implanted into the sputtering film is one.   The method for producing a reflective mask blank for EUVL according to any one of claims 1 to 11, wherein the number of times ions are implanted into the sputtering film is two or more. The total injection amount of the silver ion is ^{1 × 10 14 / cm 2 ~5} × 10 17 / cm 2, the manufacturing method of the reflective mask blank for EUVL according to any one of claims 10 to 13.   The method for manufacturing a reflective mask blank for EUVL according to claim 1, wherein a low reflection layer for inspection light of a mask pattern is formed on the absorption layer.   The reflective type for EUVL according to claim 15, wherein after forming the sputtering formation film, the low reflection layer is formed on the sputtering formation film, and the ions are implanted into the sputtering formation film from the low reflection layer side. Mask blank manufacturing method.   The method of manufacturing a reflective mask blank for EUVL according to claim 15, wherein the low reflective layer is formed after forming the sputtering formed film and implanting ions into the sputtering formed film.