JP6661724B2 - Reflective mask blank, reflective mask and method of manufacturing the same, and method of manufacturing semiconductor device - Google Patents

Description

  The present invention relates to a reflective mask blank, a reflective mask, a method of manufacturing the same, and a method of manufacturing a semiconductor device, which are original plates for manufacturing an exposure mask used for manufacturing a semiconductor device.

  With the recent demand for higher density and higher precision of VLSI devices, EUV lithography, which is an exposure technology using Extreme Ultraviolet (hereinafter abbreviated as “EUV”) light, is expected to be promising. I have. Here, the EUV light refers to light in a wavelength band in a soft X-ray region or a vacuum ultraviolet region, and specifically, light having a wavelength of about 0.2 to 100 nm.

  Such a reflective mask has a multilayer reflective film that reflects exposure light formed on a substrate, and an absorber film that absorbs the exposure light is formed in a pattern on the multilayer reflective film. Light incident on a reflective mask mounted on an exposure machine (pattern transfer device) is absorbed in a portion with an absorber film, and in a portion without an absorber film, a light image reflected by a multilayer reflective film is reflected by a reflection optical system. Is transferred onto the semiconductor substrate.

In order to achieve higher density and higher precision of a semiconductor device using such a reflective mask, the reflective region (the surface of the multilayer reflective film) of the reflective mask is highly exposed to EUV light as exposure light. It is required that a high contrast be obtained between the absorber film pattern having the reflectance and the exposure light.
The multilayer reflective film is a multilayer film in which elements having different refractive indices are periodically laminated, and in general, a thin film of a heavy element or a compound thereof and a thin film of a light element or a compound thereof alternately form 40 to 40. A multilayer film that is stacked for about 60 periods is used. For example, as the 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 periods is preferably used.

As a reflection type mask blank which is an original plate for manufacturing a reflection type mask used in the EUV lithography, for example, a reflection type mask blank for EUV lithography described in Patent Document 1 below has been proposed.
That is, in Patent Document 1, a reflective layer that reflects EUV light and an absorber layer that absorbs EUV light are formed in this order on a substrate, and the absorber layer is made of tantalum (Ta), boron (B) ), Silicon (Si), and nitrogen (N) in a predetermined content ratio are disclosed. In Patent Document 1, a low-reflection layer for inspection light used for inspection of a mask pattern is formed on the absorber layer, and the low-reflection layer is formed of tantalum (Ta), boron (B), silicon ( There is also disclosed a reflective mask blank for EUV lithography containing Si) and oxygen (O) at a predetermined content ratio.

  Patent Document 2 below discloses that at least two types of substances having different optical constants are provided on a reflecting surface composed of a multilayer reflective film in which at least two types of substances having different optical constants are alternately laminated with a predetermined film thickness. There is disclosed a reflective mask provided with a non-reflective portion in which a multilayer antireflection film alternately laminated with a film thickness different from a predetermined film thickness in a reflective film is formed in a pattern.

Japanese Patent No. 4867695 Japanese Patent No. 2545905

  In the conventional reflective mask blank disclosed in Patent Document 1 and the reflective mask manufactured from the reflective mask blank as described above, the thickness of the absorber layer is such that the EUV light as the exposure light is sufficiently applied. It was necessary to have a thickness that could be absorbed, and usually required a thickness exceeding 60 nm. In the case of a laminated structure of the absorber layer and the low reflection layer, the thickness was set to 70 nm or more.

  However, in an exposure apparatus in which exposure light is incident at a predetermined angle (approximately 6 degrees incident angle) with respect to a reflective mask, if an absorber layer pattern having a thickness exceeding 60 nm is formed as described above, An area where the reflection area becomes a shadow (shadowing) due to the absorber layer pattern occurs, and the image reflected by the reflection area does not match the patterning image, resulting in a serious problem that the accuracy of the transfer pattern is deteriorated. Further, in the formation of an absorber pattern having a narrow width (for example, 20 nm or less), the aspect ratio is increased, and the pattern may be embrittled or a defect due to falling may occur.

  On the other hand, in the reflection type mask having the non-reflection portion of the multilayer film disclosed in Patent Document 2, the exposure light reflectance at the non-reflection portion can be suppressed to at most about 3%. In order to perform high-precision pattern transfer in EUV lithography, it is necessary to suppress the exposure light reflectance at the non-reflection portion to, for example, 2% or less, and it is difficult to realize the reflection type mask disclosed in Patent Document 2 described above. is there. Further, in order to manufacture the reflective mask disclosed in Patent Document 2, a resist pattern is formed on a reflective surface made of a predetermined multilayer reflective film, and then a non-reflective portion of the multilayer film is formed. Finally, since the resist pattern is stripped, it is difficult to form a high-definition mask pattern, and process defects are likely to occur in the non-reflective multilayer film.

  Therefore, an object of the present invention is to firstly provide a reflective mask blank and a reflective mask which can suppress the reflectance of EUV light to an absorber film to 2% or less, and secondly, to provide a conventional mask. Thirdly, it is possible to provide a reflective mask blank and a reflective mask which can obtain a low reflectance for EUV light with a thin film thickness of the absorber film, and thirdly, a reflection using such a reflective mask blank. An object of the present invention is to provide a method of manufacturing a mold mask and a method of manufacturing a semiconductor device.

The present inventor has made intensive studies to solve the above problems, and as a result, completed the present invention having the following configuration.
(Configuration 1)
A reflective type comprising: a multilayer reflective film for reflecting EUV light on a substrate; a protective film having an etching preventing function for protecting the multilayer reflective film on the multilayer reflective film; and an absorber film on the protective film. A mask blank, wherein the multilayer reflective film has a configuration in which a multilayer structure in which a low-refractive index layer and a high refractive index layer are stacked on the substrate is stacked in a plurality of cycles with one cycle, and the absorber film is A phase control layer, and a layered film in which high refractive index material layers and low refractive index material layers are alternately laminated on the phase control layer. The reflection at each interface between the low-refractive index layer and the high-refractive index layer constituting the reflective film and the reflected light (A) due to the reflection on the surface of the protective film, and the phase control constituting the absorber film Layer, the high refractive index material layer, and each of the low refractive index material layer The thickness of the phase control layer is set so that the reflectivity of EUV light to the absorber film is 2% or less due to the difference in the phase of the reflected light (B) due to reflection on the surface. Characteristic reflective mask blank.

As in the above configuration 1, the reflective mask blank of the present invention has a multilayer reflective film for reflecting EUV light on a substrate, and an etching preventing function for protecting the multilayer reflective film on the multilayer reflective film. A reflective mask blank comprising a protective film and an absorber film on the protective film, wherein the multilayer reflective film has a laminated structure in which a low refractive index layer and a high refractive index layer are laminated on the substrate. The absorber film is a phase control layer, and a multilayer film in which a high refractive index material layer and a low refractive index material layer are alternately laminated on the phase control layer. The reflection at the interface between the low refractive index layer and the high refractive index layer constituting the multilayer reflective film, which is incident on the reflective mask blank, and due to the reflection at the surface of the protective film. The reflected light (A) and the phase constituting the absorber The phase of the reflected light (B) due to reflection at each interface with the control layer, the high refractive index material layer, and the low refractive index material layer is different, so that the reflectance of the EUV light to the absorber film is 2%. By setting the thickness of the phase control layer so as to be as follows, the reflectivity of EUV light to the absorber film can be suppressed to 2% or less, and the contrast with the reflection region can be increased. High-definition pattern transfer can be realized by using a reflective mask manufactured using the reflective mask blank of the present invention.
Further, according to Configuration 1, a low reflectance (for example, 2% or less) for EUV light can be obtained with a thinner absorber film thickness than before, so that the absorber film can be made thinner than before. Various problems caused by conventional shadowing and high aspect ratio can be solved.

(Configuration 2)
The phase control layer is incident on the reflective mask blank, and has a film thickness set so that the phases of the reflected light (A) and the reflected light (B) are different by 180 ° ± 10 °. The reflective mask blank according to Configuration 1, wherein:
As in the above configuration 2, the phase control layer is incident on the reflective mask blank, and the phases of the reflected light (A) and the reflected light (B) are different from each other by 180 ° ± 10 °. By setting the film thickness, the reflected light from the multilayer reflective film that passes through the absorber film is canceled by the reflected light from the absorber film that has the opposite phase to that of the absorber film, and the reflected light in the EUV light absorption region is suppressed. As a result, the reflectivity of EUV light to the absorber film can be suppressed to 2% or less, and a lower reflectivity to EUV light can be obtained with a thinner absorber film thickness than before. Can be.

(Configuration 3)
The reflective mask blank according to Configuration 1 or 2, wherein the phase control layer is made of a material having an extinction coefficient k at a wavelength of 13.5 nm of 0.03 or more.
In the present invention, from the viewpoint of suppressing the EUV light reflectance of the above-mentioned absorber film to 2% or less and making the absorber film thinner than before, the phase control layer has an extinction coefficient k of 0.1. It is preferable to select 03 or more materials.

(Configuration 4)
The low refractive index material layer constituting the absorber film has a refractive index n (low) at a wavelength of 13.5 nm of 0.95 or less, an extinction coefficient k (low) of 0.03 or more, The high refractive index material layer constituting the film has a refractive index n (high) at a wavelength of 13.5 nm,
n (high) ≧ 1.46 × n (low) −0.41
4. The reflective mask blank according to any one of the constitutions 1 to 3, wherein the following condition is satisfied.
In the present invention, from the viewpoint of suppressing the EUV light reflectance of the above-described absorber film to 2% or less and making the absorber film thinner than before, a low refractive index material layer constituting the absorber film and It is preferable that each of the high refractive index material layers has a refractive index and an extinction coefficient satisfying the conditions of the fourth aspect.

(Configuration 5)
A reflective type comprising: a multilayer reflective film for reflecting EUV light on a substrate; a protective film having an etching preventing function for protecting the multilayer reflective film on the multilayer reflective film; and an absorber film on the protective film. A mask blank, wherein the multilayer reflective film has a configuration in which a multilayer structure in which a low-refractive index layer and a high refractive index layer are stacked on the substrate is stacked in a plurality of cycles with one cycle, and the absorber film is A phase control layer, and a laminated film in which a high refractive index material layer and a low refractive index material layer are alternately laminated on the phase control layer, and the thickness of the absorber film is 60 nm or less. Wherein the phase control layer is a material having an extinction coefficient k of 0.03 or more at a wavelength of 13.5 nm, and the low refractive index material layer has a refractive index n (low) of 0 at a wavelength of 13.5 nm. 0.95 or less, the extinction coefficient k (low) is 0.03 or more, The high refractive index material layer constituting the film has a refractive index n (high) at a wavelength of 13.5 nm,
n (high) ≧ 1.46 × n (low) −0.41
Wherein the film thickness of the phase control layer is set so that the reflectivity of EUV light to the absorber film is equal to or less than a predetermined reflectivity. Mold mask blank.

As described in the above configuration 5, the reflective mask blank of the present invention has a multilayer reflective film for reflecting EUV light on a substrate, and an etching preventing function on the multilayer reflective film for protecting the multilayer reflective film. A reflective mask blank comprising a protective film and an absorber film on the protective film, wherein the multilayer reflective film has a laminated structure in which a low refractive index layer and a high refractive index layer are laminated on the substrate. The absorber film has a configuration in which a plurality of cycles are stacked as a cycle, and the absorber film is formed by alternately stacking a high refractive index material layer and a low refractive index material layer on the phase control layer. The phase control layer is made of a material having an extinction coefficient k of 0.03 or more at a wavelength of 13.5 nm, and the low refractive index The material layer has a refractive index n (low) at a wavelength of 13.5 nm of 0. 95 or less, the extinction coefficient k (low) is 0.03 or more, the high refractive index material layer forming the absorber film, the refractive index n (high) at a wavelength of 13.5 nm,
n (high) ≧ 1.46 × n (low) −0.41
And the thickness of the phase control layer is set so that the reflectivity of EUV light to the absorber film is equal to or less than a predetermined reflectivity. Since a low reflectance (for example, 2% or less) for EUV light can be obtained with the thickness of the absorber film (60 nm or less), the absorber film can be made thinner than before, and the conventional shadowing and high aspect ratio can be obtained. A reflective mask blank that can solve various problems depending on the ratio can be obtained.

(Configuration 6)
The reflective mask blank according to Configuration 5, wherein the thickness of the phase control layer is set so that the reflectivity of EUV light to the absorber film is 2% or less.
As in the above configuration 6, the thickness of the phase control layer is set so that the reflectance of the EUV light to the absorber film is 2% or less, so that the reflection of the EUV light to the absorber film is reduced. The ratio can be suppressed to 2% or less, the contrast with the reflection area can be increased, and high-definition pattern transfer can be realized using the reflection mask manufactured using the reflection mask blank of the present invention. it can.

(Configuration 7)
7. A method for manufacturing a reflective mask, comprising patterning the absorber film in the reflective mask blank according to any one of the constitutions 1 to 6.
As described in the above configuration 7, by manufacturing a reflective mask using the reflective mask blank of the present invention, the reflectance of EUV light to the absorber film can be suppressed to 2% or less, which is thinner than the conventional one. A reflective mask that can obtain a low reflectance for EUV light with the thickness of the absorber film can be obtained.

(Configuration 8)
A multilayer reflective film that reflects EUV light on a substrate, a protective film having an etching preventing function for protecting the multilayer reflective film on the multilayer reflective film, and a transfer pattern including an absorber film on the protective film. Wherein the multilayer reflective film has a structure in which a multilayer structure in which a low refractive index layer and a high refractive index layer are laminated on the substrate is formed in a plurality of periods as one period. The body film is composed of a phase control layer and a laminated film in which a high-refractive-index material layer and a low-refractive-index material layer are alternately laminated on the phase control layer, and is incident on the reflective mask. The light reflected at each interface between the low-refractive-index layer and the high-refractive-index layer constituting the multilayer reflective film and the reflected light (A) due to the reflection on the surface of the protective film, and the phase constituting the absorber Control layer, the high refractive index material layer, and the low refractive index material layer The thickness of the phase control layer is set so that the phase of the reflected light (B) due to reflection at each interface is different, so that the reflectance of the EUV light to the absorber film is 2% or less. A reflective mask characterized by the following.

As in the above configuration 8, the reflection type mask of the present invention comprises a multilayer reflective film for reflecting EUV light on a substrate, and a protective film having an etching preventing function for protecting the multilayer reflective film on the multilayer reflective film. A reflective mask comprising a film and a transfer pattern comprising an absorber film on the protective film, wherein the multilayer reflective film has a laminated structure in which a low refractive index layer and a high refractive index layer are laminated on the substrate. And a plurality of cycles are laminated as one cycle, wherein the absorber film has a phase control layer and a high refractive index material layer and a low refractive index material layer alternately laminated on the phase control layer. And reflection at each interface between the low refractive index layer and the high refractive index layer constituting the multilayer reflective film, and reflection at the surface of the protective film. (A) reflected by light and the phase control constituting the absorber Since the phase of the reflected light (B) due to reflection at each interface between the high refractive index material layer and the low refractive index material layer is different, the reflectivity of EUV light to the absorber film is 2% or less. By setting the thickness of the phase control so that the reflectance of EUV light to the absorber film can be suppressed to 2% or less, the contrast with the reflection region can be increased, and the reflection of the present invention can be improved. High-definition pattern transfer can be realized using a mold mask.
Further, according to Configuration 8, the reflective mask of the present invention can obtain a low reflectance (for example, 2% or less) with respect to EUV light with a thinner absorber film thickness than the conventional one. Can be reduced in thickness, and various problems caused by the conventional shadowing and high aspect ratio can be solved.

(Configuration 9)
The phase control layer is incident on the reflective mask, and has a thickness set so that the phase of the reflected light (A) and the phase of the reflected light (B) are different by 180 ° ± 10 °. The reflective mask according to Configuration 8, characterized in that:
As in the above configuration 9, the phase control layer is incident on the reflective mask, and the film is formed such that the phases of the reflected light (A) and the reflected light (B) are different by 180 ° ± 10 °. By setting the thickness, the reflected light from the multilayer reflective film that has passed through the absorber film and is canceled by the reflected light from the absorber film having the opposite phase to that of the absorber film, thereby suppressing the reflected light in the EUV light absorption region. As a result, the reflectivity of EUV light to the absorber film can be suppressed to 2% or less, and a lower reflectivity to EUV light can be obtained with a thinner absorber film thickness than before. it can.

(Configuration 10)
A multilayer reflective film that reflects EUV light on a substrate, a protective film having an etching preventing function for protecting the multilayer reflective film on the multilayer reflective film, and a transfer pattern including an absorber film on the protective film. Wherein the multilayer reflective film has a structure in which a multilayer structure in which a low refractive index layer and a high refractive index layer are laminated on the substrate is formed in a plurality of periods as one period. The body film is composed of a phase control layer, and a laminated film in which a high refractive index material layer and a low refractive index material layer are alternately laminated on the phase control layer, and the thickness of the absorber film Is 60 nm or less, the phase control layer is a material having an extinction coefficient k at a wavelength of 13.5 nm of 0.03 or more, and the low refractive index material layer is a material having a refractive index n (low) at a wavelength of 13.5 nm. ) Is 0.95 or less, and the extinction coefficient k (low) is 0.03 or more. The high refractive index material layer constituting the absorber film has a refractive index n (high) at a wavelength of 13.5 nm,
n (high) ≧ 1.46 × n (low) −0.41
A material that satisfies the condition represented by the above, and the reflectance of EUV light in the transfer pattern formation region can recognize the transfer pattern with respect to the reflectance of EUV light in the reflection region where the transfer pattern is exposed. A reflection type mask, wherein the thickness of the phase control layer is set so as to have a difference.

As in the above configuration 10, the reflection type mask of the present invention comprises a multilayer reflective film for reflecting EUV light on a substrate, and a protective film having an etching preventing function for protecting the multilayer reflective film on the multilayer reflective film. A reflective mask comprising a film and a transfer pattern comprising an absorber film on the protective film, wherein the multilayer reflective film has a laminated structure in which a low refractive index layer and a high refractive index layer are laminated on the substrate. Is a plurality of cycles with one cycle as a cycle, wherein the absorber film is formed by alternately stacking a phase control layer and a high refractive index material layer and a low refractive index material layer on the phase control layer. A thickness of the absorber film is 60 nm or less, and the phase control layer is made of a material having an extinction coefficient k of 0.03 or more at a wavelength of 13.5 nm. The refractive index material layer has a refractive index n (low) at a wavelength of 13.5 nm. ) Is 0.95 or less, the extinction coefficient k (low) is 0.03 or more, and the high refractive index material layer constituting the absorber film has a refractive index n (high) at a wavelength of 13.5 nm,
n (high) ≧ 1.46 × n (low) −0.41
Wherein the reflectivity of EUV light in the transfer pattern forming region is equal to the reflectivity of EUV light in the reflective region where the transfer pattern is exposed (that is, the region without the transfer pattern). On the other hand, since the thickness of the phase control layer is set so as to have a difference to the extent that the transfer pattern can be recognized, the thickness of the absorber film (60 nm or less), which is thinner than the conventional one, is low with respect to EUV light. Since a reflectance (for example, 2% or less) can be obtained, the absorber film can be made thinner than before, and a reflection type mask that can solve various problems due to the conventional shadowing and high aspect ratio. Is obtained.

(Configuration 11)
The reflective mask according to Configuration 10, wherein the thickness of the phase control layer is set so that the reflectivity of EUV light to the absorber film is 2% or less.
As in the above configuration 11, the thickness of the phase control layer is set so that the reflectance of the EUV light to the absorber film is 2% or less, whereby the reflection of the EUV light to the absorber film is reduced. Since the ratio can be suppressed to 2% or less, the contrast between the transfer pattern forming region and the reflection region where the transfer pattern is exposed can be increased, and high-definition pattern transfer can be realized using a reflective mask. it can.

(Configuration 12)
A method of forming a pattern on a semiconductor substrate using the reflective mask obtained by the manufacturing method described in Structure 7 or the reflective mask described in any of Structures 8 to 11 Production method.
As described in the above configuration 12, by manufacturing a semiconductor device by forming a pattern on a semiconductor substrate by pattern transfer using the reflective mask of the present invention, a high-quality semiconductor device with few defects can be obtained. .

According to the present invention, it is possible to obtain a reflective mask blank and a reflective mask that can suppress the reflectance of EUV light to the absorber film to 2% or less.
Further, according to the present invention, it is possible to obtain a reflective mask blank and a reflective mask capable of obtaining a low reflectance with respect to EUV light with a thinner absorber film thickness than before.
Further, by manufacturing a reflective mask using the reflective mask blank of the present invention, the reflectance of EUV light to the absorber film can be suppressed to 2% or less, and the thickness of the absorber film is thinner than before. Thus, it is possible to obtain a reflection type mask capable of obtaining a low reflectance for EUV light.
Furthermore, by manufacturing a semiconductor device by pattern formation using the reflective mask of the present invention, a high-quality semiconductor device with few defects can be obtained.

1 is a cross-sectional view illustrating a layer configuration of an embodiment of a reflective mask blank according to the present invention. FIG. 1 is a cross-sectional view showing a detailed layer configuration of an embodiment of a reflective mask blank according to the present invention. It is sectional drawing which shows the layer structure of the reflection type mask which concerns on this invention.

Hereinafter, embodiments of the present invention will be described in detail.
[Reflective mask blank]
First, the reflective mask blank according to the present invention will be described.
FIG. 1 is a cross-sectional view showing a layer configuration of an embodiment of a reflection type mask blank according to the present invention. A multilayer reflection film 2 that reflects EUV light as exposure light, and a multilayer reflection film 2 are formed on a substrate 1. 1 shows a reflective mask blank 10 having a structure including a protective film 3 for protecting the film and an absorber film 4 for forming a transfer pattern for absorbing EUV light.
Although not shown, a back surface conductive film can be provided on the side of the substrate 1 opposite to the side on which the multilayer reflective film and the like are formed.

In the case of EUV exposure, the substrate 1 having a low coefficient of thermal expansion within a range of 0 ± 5 ppb / ° C. is preferably used in order to prevent pattern distortion due to heat during exposure. As a material having the above, for example, SiO ₂ —TiO ₂ glass, a multi-component glass ceramic, or the like can be used.

  The main surface of the substrate 1 on which the transfer pattern is formed is processed to have a high flatness from the viewpoint of obtaining at least pattern transfer accuracy and positional 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, and particularly preferably, in a 132 mm × 132 mm region of the main surface on the side where the transfer pattern of the substrate is formed. Is 0.03 μm or less. The main surface opposite to the side on which the transfer pattern is formed is a surface to be electrostatically chucked when set in an exposure apparatus, and has a flatness of 1 μm or less, more preferably 0 μm, in a 142 mm × 142 mm area. 0.5 μm or less, particularly preferably 0.03 μm or less.

  In the case of EUV exposure, the surface smoothness required for the substrate 1 is such that the surface roughness of the main surface on the side where the transfer pattern of the substrate is formed is 0.1 nm or less in root mean square roughness (RMS). It is preferred that

  The multilayer reflective film 2 is a multilayer film in which elements having different refractive indices are periodically laminated, and generally includes a thin film (low refractive index layer) of a heavy element which is a low refractive index material or a compound thereof. A multilayer film is used in which thin films (high-refractive-index layers) of light elements or compounds thereof, which are high-refractive-index materials, are alternately stacked for about 40 to 60 periods. The multilayer reflective film 2 may have a multilayer structure in which a high refractive index layer and a low refractive index layer are stacked in this order from the substrate side, as a single cycle, or may be stacked a plurality of times, or a low refractive index layer and a high refractive index layer from the substrate side. May be stacked in a plurality of cycles with a stacked structure in which the layers are stacked in this order as one cycle. As the low refractive index material, an element selected from Mo, Ru, Rh, and Pt or an alloy thereof is used, and as the high refractive index material, Si or a Si compound is used. For example, as the 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 to 60 cycles is preferably used.

  The multilayer reflective film 2 can be formed by forming each layer by, for example, an ion beam sputtering method. In the case of the above-described Mo / Si periodic multilayer film, for example, an Si film having a thickness of about several nm is first formed using a Si target by, for example, an ion beam sputtering method, and thereafter, a Si film having a thickness of about several nm is used using a Mo target. An Mo film is formed, and this is one cycle, and 40 to 60 cycles are stacked.

  In this embodiment, a protective film 3 (also referred to as a capping layer or a buffer layer) for protecting the multilayer reflective film when patterning or correcting the pattern of the absorber film is formed on the multilayer reflective film 2. )). As a material of such a protective film 3, for example, ruthenium or a ruthenium compound containing at least one element of niobium, zirconium, and rhodium in addition to silicon is preferably used. In addition, a chromium-based material may be used. Further, the protective film 3 may be a laminated film of the above-described materials.

When the protective film 3 is made of ruthenium or a ruthenium compound, its thickness is preferably, for example, in the range of 1 nm to 5 nm. If the thickness is less than 1 nm, the function of protecting the multilayer reflective film may not be sufficiently obtained. On the other hand, if the thickness is more than 5 nm, the reflectance of the multilayer reflective film having the protective film to be the reflective region of the mask may be reduced.
When the protective film is a stacked film of silicon and ruthenium or a ruthenium compound, the thickness of the stacked film is preferably, for example, in a range of 6.5 nm to 7 nm.

  The method for forming the protective film 3 is not particularly limited, and an ion beam sputtering method, a magnetron sputtering method, or the like is usually applied. From the viewpoint of reducing defects, the multilayer reflective film 2 and the protective film 3 are continuously formed. It is desirable to form a film by an ion beam sputtering method. This is because, if a different film forming method is performed after the multilayer reflective film 2 is formed, the substrate is once exposed to the atmosphere, and there is a possibility of dust generation.

FIG. 2 is a cross-sectional view showing a detailed layer configuration of one embodiment of the above-mentioned reflective mask blank according to the present invention.
As shown in FIG. 2, the reflective mask blank 10 of the present embodiment has a multilayer structure in which a Si film 21 as a high refractive index layer and a Mo film 22 as a low refractive index layer are alternately laminated on a substrate 1. A reflective film 2 is provided. In this case, the uppermost layer of the multilayer reflective film 2 is the Mo film 22.

  Further, the protective film 3 provided on the multilayer reflective film 2 has a Mo film as the uppermost layer of the multilayer reflective film 2, and has a silicon film for suppressing a decrease in reflectance and an etching prevention function. A laminated film with the above-mentioned ruthenium compound film is preferred.

Further, the absorber film 4 has a function of absorbing EUV light as exposure light. In the present invention, the absorber film 4 is configured as a phase control layer 41 and a laminated film in which a high refractive index material layer 42 and a low refractive index material layer 43 are alternately laminated on the phase control layer 41. And reflected at each interface between the Mo film 22 as the low refractive index layer and the Si film 21 as the high refractive index layer, which are incident on the reflective mask blank 10 and constitute the multilayer reflective film 2, and Each of the reflected light (A) due to the reflection on the surface of the protective film 3 and the phase control layer 41, the high refractive index material layer 42, and the low refractive index material layer 43 constituting the absorber film 4 The thickness of the phase control layer 41 is set so that the phase of the reflected light (B) due to the reflection at the interface is different, so that the reflectance of the EUV light to the absorber film is 2% or less. It is characterized by.
In the present invention, the EUV light reflectance refers to the reflectance measured when EUV light is incident on the reflective mask blank at an incident angle of 6.0 degrees.

As described above, in the reflective mask blank of the present invention, the absorber film 4 includes the phase control layer 41 and the high-refractive-index material layers 42 and the low-refractive-index material layers 43 on the phase control layer 41 alternately. Each of the Mo film 22 serving as a low refractive index layer and the Si film 21 serving as the high refractive index layer, which are incident on the reflective mask blank 10 and constitute the multilayer reflective film 2. The reflected light (A) due to the reflection at the interface and the reflection at the surface of the protective film 3, and the phase control layer 41, the high refractive index material layer 42, and the low refractive index that constitute the absorber film 4. The phase of the phase control layer 41 is adjusted so that the phase of the reflected light (B) due to reflection at each interface with the index material layer 43 is different, so that the reflectance of the EUV light to the absorber film is 2% or less. By setting the thickness, E with respect to the absorber film The reflectance of V light can be suppressed to 2% or less, the contrast with the reflection area can be enhanced, and high-definition pattern transfer can be performed using a reflection mask manufactured using the reflection mask blank of the present invention. Can be realized.
In addition, the reflective mask blank of the present invention can obtain a low reflectance (for example, 2% or less) for EUV light with a thinner absorber film thickness than in the related art. That is, since the absorber film can be made thinner than before, various problems due to the shadowing and the high aspect ratio in the above-described conventional technology can be solved.

  In order to more effectively exert the above-described effects of the present invention, the phase control layer is incident on a reflective mask blank, and the phase of the reflected light (A) and the reflected light (B) is changed. However, it is desirable that the film thickness is set so as to differ by 180 ° ± 10 °.

  In one embodiment of the present invention shown in FIG. 2, the absorber film 4 includes a phase control layer 41 and an alternately laminated film of a high refractive index material layer 42 and a low refractive index material layer 43 thereon. I have. In order to obtain the effect of reducing the thickness of the absorber film 4, it is preferable that the material of the phase control layer 41 has a extinction coefficient k of 0.03 or more at a wavelength of 13.5 nm. Preferably, the material of the phase control layer 41 has an extinction coefficient k at a wavelength of 13.5 nm of 0.03 or more and 0.1 or less. Here, the lowermost phase control layer 41 of the absorber film 4 and the respective lower refractive index material layers 43 thereon may be the same material or different materials. Further, the thicknesses of the phase control layer 41 and the low refractive index material layer 43 may be the same or different. Further, it is preferable that the alternately laminated films of the high refractive index material layer 42 and the low refractive index material layer 43 on the phase control layer 41 have the same period length. Although the effect of reducing the thickness of the absorber film 4 and the effect of reducing the reflectance are reduced, the absorber film 4 may be replaced with the phase control layer 41 and the low-level layer thereon without departing from the effects of the present invention. It may be composed of alternately laminated films of the refractive index material layer 43 and the high refractive index material layer 42. The phase control layer 41 reflects at each interface between the Mo film of the low refractive index layer and the Si film of the high refractive index layer constituting the multilayer reflective film 2 and the reflection at the surface of the protective film 3. (A) is different from the phase of the reflected light (B) due to the reflection at each interface between the phase control layer 41, the high refractive index material layer 42, and the low refractive index material layer 43 that constitute the absorber film. As described above, the layer has a function of adjusting the phase.

As shown in FIG. 2, the phase control layer 41 is incident on the reflective mask blank 10 and forms each of the phase control layer 41, the high refractive index material layer 42, and the low refractive index material layer 43 constituting the absorber film 4. The reflected light B due to the reflection at the interface, and the reflection at each interface between the Mo film of the low refractive index layer and the Si film of the high refractive index layer that pass through the absorber film 4 and constitute the multilayer reflective film 2; Since the phase of the reflected light A due to the reflection on the surface of the protective film differs by 180 ° ± 10 °, the reflected light A transmitted through the absorber film 4 and reflected from the multilayer reflective film 2 is converted into an absorber film having a phase opposite to that of the reflected light A. Thus, the reflected light B can cancel out the reflected light in the EUV light absorption region. Therefore, as a result, the reflectance of EUV light to the absorber film 4 (EUV light absorption region) can be suppressed to 2% or less. In addition, when the absorber film 4 has the multilayer structure of the present invention, a lower reflectance with respect to EUV light can be obtained with a thinner absorber film thickness than before.
In the present invention, the phase difference between EUV light (reflected light B) reflected by the absorber film 4 and EUV light (reflected light A) transmitted through the absorber film 4 and reflected by the multilayer reflective film 2 is: More preferably, it is 180 ° ± 7.5 °.

In the reflective mask blank of the present invention, as described above, the EUV light reflectance of the absorber film 4 can be 2% or less. It is preferably at most 1%, more preferably at most 0.5%, most preferably at most 0.2%.
In the reflective mask blank of the present invention, the thickness of the absorber film can be reduced, and is preferably, for example, 60 nm or less. More preferably, it is 50 nm or less, still more preferably 45 nm or less, and most preferably 40 nm or less.

In order to satisfy the above-mentioned EUV light reflectance and the thickness of the absorber film, the respective refractive indices of the low refractive index material layer 43 and the high refractive index material layer 42 constituting the absorber film 4 of the multilayer film of the present invention, The extinction coefficient preferably satisfies the following conditions.
That is, the low refractive index material layer 43 constituting the absorber film 4 has a refractive index n (low) at a wavelength of 13.5 nm of 0.95 or less and an extinction coefficient k (low) of 0.03. It is preferable that it is above. More preferably, the low refractive index material layer 43 has a refractive index n (low) at a wavelength of 13.5 nm of 0.93 or less and an extinction coefficient k (low) of 0.04 or more. desirable. In the low refractive index material layer 43, the lower limit of the refractive index n (low) at a wavelength of 13.5 nm is 0.83 or more, and the upper limit of the extinction coefficient k (low) is 0.1 or less. preferable.

The high refractive index material layer 42 constituting the absorber film 4 has a refractive index n (high) at a wavelength of 13.5 nm.
n (high) ≧ 1.46 × n (low) −0.41
It is preferable to satisfy the condition represented by The extinction coefficient of the high-refractive-index material layer 42 is not particularly limited and is arbitrary.

  In the present invention, from the viewpoint of suppressing the EUV light reflectance of the above-described absorber film to 2% or less and making the absorber film thinner than before, a low refractive index material layer constituting the absorber film and The high refractive index material layer preferably has each refractive index and extinction coefficient satisfying the above conditions.

That is, the absorber film 4 is configured by a phase control layer 41, and a laminated film in which a high refractive index material layer 42 and a low refractive index material layer 43 are alternately laminated on the phase control layer 41, and The thickness of the absorber film 4 is, for example, 60 nm or less, the phase control layer 41 is a material having an extinction coefficient k of 0.03 or more at a wavelength of 13.5 nm, and the low refractive index material layer 43 is The refractive index n (low) at a wavelength of 13.5 nm is 0.95 or less, the extinction coefficient k (low) is 0.03 or more, and the high refractive index material layer constituting the absorber film has a wavelength of 13 The refractive index n (high) at 0.5 nm is
n (high) ≧ 1.46 × n (low) −0.41
And the thickness of the phase control layer 41 is set so that the reflectivity of EUV light to the absorber film 4 is equal to or less than a predetermined reflectivity. Since a low reflectance (for example, 2% or less) with respect to EUV light can be obtained with a thin absorber film thickness (60 nm or less), the absorber film can be made thinner than before, and the conventional shadowing and shadowing A reflective mask blank that can solve various problems caused by a high aspect ratio can be obtained.

The phase control layer applicable to the absorber film of the reflective mask blank of the present invention, and as the material of the low refractive index material layer, for example, Ta, Cr, Ag, Pd, W, Fe, Pt, Au, Co , Ir, Ni, at least one metal selected from Sn, or an alloy containing the metal, and the metal, oxide, nitride, carbide, oxynitride, oxycarbide, nitrided carbide, oxynitride carbide of the alloy, Preferable examples include boride, boride oxide, boride nitride, and boride oxynitride.
Further, the material of the high refractive index material layer applicable to the absorber film of the reflective mask blank of the present invention, for example, at least selected from Si, Al, Cu, Zn, Te, Ge, Mg, Hf, Zr One kind of metal or an alloy containing the metal, and an oxide, nitride, carbide, oxynitride, oxycarbide, nitride carbide, oxynitride carbide, boride, boride oxide, boride of the metal or alloy Preference is given to nitrides, boride oxynitrides and the like.
Note that when the phase control layer, the low refractive index material layer, and the high refractive index material layer employ boride, boride oxide, boride nitride, or boride oxynitride of the metal or an alloy containing a metal, Since the crystal structure has an amorphous structure, the surface of the absorber film can be smoothed, and an effect such that a fatal defect can be easily detected in a defect inspection is obtained.

  Table 1 below shows combinations of materials of the low-refractive-index material layer and the high-refractive-index material layer included in the preferable ranges of the refractive index n and the extinction coefficient k.

  In Table 1 above, “○” indicates a preferable material in which the thickness of the absorber film is 50 nm or less in 3 to 6 periods when the laminated structure of the high refractive index material layer and the low refractive index material layer is one cycle. The symbol “は” indicates that when the laminated structure of the high-refractive-index material layer and the low-refractive-index material layer is defined as one cycle, two cycles, the thickness of the absorber film is 20 nm or less, and the reflectance is 2%. The following are more preferable combinations of materials.

The method of forming the absorber film 4 is not particularly limited, but in the present invention, from the viewpoint that the absorber film is formed of a phase control layer, a laminated film of a low refractive index material layer and a high refractive index material layer, It is preferably formed by an ion beam sputtering method. In this case, the materials of the phase control layer, the high refractive index layer and the low refractive index layer are preferably the metals or alloys listed above. In addition, by forming the multilayer reflective film 2, the protective film 3, and the absorber film 4 successively by an ion beam sputtering method, a defect reducing effect can be obtained. For example, when the DC sputtering method is applied to the formation of the absorber film as in the related art, the substrate is once exposed to the atmosphere after the formation of the multilayer reflective film (and the protective film). is there.
The thicknesses and repetition periods of the low refractive index material layer and the high refractive index material layer constituting the absorber film 4 cannot be said unconditionally because they vary depending on the material applied to the absorber film. It is preferable to determine the value appropriately according to the method.
In addition, assuming that a defect inspection using inspection light having a longer wavelength than EUV light having a wavelength of 193 nm or 257 nm is performed on a reflective mask blank, the effects of the present invention (thinning effect and reflectivity for EUV light) are considered. ) May be provided on the absorber film 4 with an anti-reflection film having a reflectance-reducing effect on the inspection light.

  Further, the reflective mask blank may be in a state where a resist film for forming a predetermined transfer pattern is formed on the absorber film.

  As described above, according to the reflective mask blank of the present invention, the reflectivity of EUV light to the absorber film can be suppressed to 2% or less. High-definition pattern transfer can be realized using a mold mask. In addition, a low reflectance (for example, 2% or less) for EUV light can be obtained with a thinner absorber film thickness than before, so that the absorber film can be made thinner than before, and the shadowing and high shadowing can be achieved. Various problems due to the aspect ratio can be solved.

[Reflective mask]
The present invention also provides a reflective mask and a method for manufacturing a reflective mask using the reflective mask blank having the above configuration.
FIG. 3 is a cross-sectional view showing a layer configuration of the reflective mask, and shows a reflective mask 20 including an absorber film pattern 4a in which the absorber film 4 in the reflective mask blank 10 of FIG. 1 or 2 is patterned.

  The reflective mask of the present invention includes a multilayer reflective film for reflecting EUV light on a substrate, a protective film having an etching preventing function for protecting the multilayer reflective film on the multilayer reflective film, and a protective film on the protective film. A reflective pattern mask having a transfer pattern formed of an absorber film, wherein the multilayer reflective film is formed by laminating a plurality of periods on the substrate, with a laminated structure in which a low refractive index layer and a high refractive index layer are laminated as one period. The absorber film, on the phase control layer, is composed of a laminated film of high refractive index material layers and low refractive index material layers alternately laminated, the reflective mask blank Incident light, reflected light at each interface between the low-refractive index layer and the high-refractive index layer constituting the multilayer reflective film, and reflected light (A) due to reflection at the protective film surface, and constitutes the absorber. The phase control layer, the high refractive index material layer, and the The thickness of the phase control layer is adjusted so that the phase of the reflected light (B) due to reflection at each interface with the refractive index material layer is different, so that the reflectance of the EUV light to the absorber film is 2% or less. Is set.

  When a reflective mask is manufactured using the above-described reflective mask blank of the present invention, the method of patterning the absorber film 4 serving as a transfer pattern in the reflective mask blank 10 can perform high-definition patterning. Photolithography is most preferred. In the above-described embodiment, by providing the protective film 3 having an etching preventing function for protecting the multilayer reflective film between the multilayer reflective film 2 and the absorber film 4, it is possible to form a pattern of the absorber film. A photolithography method including etching can be applied, and the multilayer reflective film can be prevented from being damaged when the absorber film is patterned.

  As described above, according to the reflective mask of the present invention, the EUV light reflectance of the absorber film can be suppressed to 2% or less. It can be used to realize high-definition pattern transfer. In addition, a low reflectance (for example, 2% or less) for EUV light can be obtained with a thinner absorber film thickness than before, so that the absorber film can be made thinner than before, and the shadowing and high shadowing can be achieved. Various problems due to the aspect ratio can be solved.

Further, as a preferred embodiment of the reflective mask of the present invention, the reflective mask has a multilayer reflective film for reflecting EUV light on a substrate, and has an etching preventing function on the multilayer reflective film for protecting the multilayer reflective film. A reflective mask including a protective film and a transfer pattern formed of an absorber film on the protective film, wherein the multilayer reflective film is formed by laminating a low refractive index layer and a high refractive index layer on the substrate. The absorber film is formed by alternately stacking a phase control layer and a high refractive index material layer and a low refractive index material layer on the phase control layer. A thickness of the absorber film is 60 nm or less, and the phase control layer is made of a material having an extinction coefficient k of 0.03 or more at a wavelength of 13.5 nm; Material layer has a refractive index at a wavelength of 13.5 nm. (low) is 0.95 or less, the extinction coefficient k (low) is 0.03 or more, and the high refractive index material layer constituting the absorber film has a refractive index n (high) at a wavelength of 13.5 nm. ,
n (high) ≧ 1.46 × n (low) −0.41
A material that satisfies the condition represented by the above, and the reflectance of EUV light in the transfer pattern formation region can recognize the transfer pattern with respect to the reflectance of EUV light in the reflection region where the transfer pattern is exposed. The reflective mask is characterized in that the thickness of the phase control layer is set so as to have a difference. With the reflective mask of this embodiment, a low reflectance (for example, 2% or less) with respect to EUV light can be obtained with a thinner absorber film thickness (60 nm or less) than before, so that the absorber film is thinner than before. Thus, a reflective mask that can solve various problems caused by the conventional shadowing and high aspect ratio can be obtained.

  Further, by manufacturing a semiconductor device by forming a desired pattern on a semiconductor substrate by pattern transfer using the reflective mask of the present invention, a high-quality semiconductor device with few defects can be obtained.

Hereinafter, embodiments of the present invention will be described more specifically with reference to examples.
(Example 1)
The substrate to be used is a SiO ₂ —TiO ₂ based glass substrate (6 inch square, 6.35 mm in thickness).
Then, the end face of the glass substrate is chamfered and ground, and the glass substrate which has been subjected to rough polishing with a polishing solution containing cerium oxide abrasive grains is set in a carrier of a double-side polishing machine. Precision polishing was performed under predetermined polishing conditions using an alkaline aqueous solution containing particles. After the completion of the precision polishing, a cleaning process was performed on the glass substrate.
As described above, a glass substrate for an EUV reflective mask blank was manufactured. The surface roughness of the main surface of the obtained glass substrate was as good as 0.10 nm or less in root mean square roughness (RMS). Further, the flatness was as good as 30 nm or less in a measurement area of 132 mm × 132 mm.

Next, a CrN conductive film is formed on the main surface (the surface to be electrostatically chucked when set in the exposure apparatus) of the glass substrate for a reflective mask blank opposite to the side on which the transfer pattern is formed as follows. did.
That is, a CrN conductive film (film thickness: 20 nm, Cr: N = 90: 10 at% ratio) was formed by a DC magnetron sputtering method using a mixed gas of argon (Ar) and nitrogen using a Cr target.

  Next, the glass substrate with a conductive film is set in an ion beam sputtering apparatus, and on the main surface of the glass substrate on which a transfer pattern is to be formed (the surface on which the conductive film is not formed) as follows. Thus, a multilayer reflective film, a protective film, and an absorber film were continuously formed.

First, as the multilayer reflection film formed on the substrate, a Mo film / Si film periodic multilayer reflection film was employed in order to make the multilayer reflection film suitable for the exposure light wavelength band of 13 to 14 nm. The multilayer reflective film was formed by alternately laminating on a substrate by ion beam sputtering using a Mo target and a Si target.
First, a Si film was formed to a thickness of 4.2 nm, and then a Mo film was formed to a thickness of 2.8 nm.

Thereafter, a protective film was formed on the multilayer reflective film by ion beam sputtering in the following manner.
First, a Si film was formed to a thickness of 4.0 nm using a Si target. Subsequently, a RuNb film was formed to a thickness of 2.5 nm using a RuNb target (Ru: Nb = 80: 20 atomic% ratio).

  Here, a sample prepared in the same manner as described above for reflectance measurement was taken out of the apparatus, and the reflectance of 13.5 nm EUV light was measured at an incident angle of 6.0 degrees with respect to the multilayer reflective film having the protective film. As a result, the reflectance was 65.3%.

Next, an absorber film was formed on the protective film by ion beam sputtering as follows.
First, using a TaB target (Ta: B = 90: 10 atomic% ratio), a TaB film of a phase control layer was formed to a thickness of 4.0 nm. Subsequently, using an Al target and a TaB target (Ta: B = 90: 10 atomic% ratio), an Al film of a high refractive index material layer was formed to a thickness of 3.5 nm, and then a TaB film of a low refractive index material layer was formed. A film having a thickness of 3.5 nm was formed, and this was taken as one cycle. Similarly, five cycles were stacked to form an absorber film composed of an alternately stacked film of an Al film and a TaB film.
As described above, the reflective mask blank of this example was manufactured.
The extinction coefficient k of the TaB film of the phase control layer at a wavelength of 13.5 nm is 0.03, the refractive index n of the Al film of the high refractive index material layer is 1.00, and the extinction coefficient k is 0.03. The refractive index n of the TaB film of the low refractive index material layer is 0.95, and the extinction coefficient k is 0.03.

When the reflectance of this reflective mask blank was measured with an EUV light of 13.5 nm at an incident angle of 6.0 degrees, the reflectance was 1.8%.
According to the reflective mask blank of this example, the total thickness of the absorber is 39.0 nm, which is significantly larger than the total thickness of the absorber of 70 nm in the reflective mask blank of the comparative example described later. It is possible to reduce the thickness.

Next, using this reflective mask blank, a reflective mask for EUV exposure having a pattern of the DRAM hp 10 nm generation in the semiconductor design rule was manufactured as follows.
First, a resist film for electron beam lithography was formed on the reflective mask blank, and a predetermined pattern was drawn using an electron beam lithography machine. After the drawing, a predetermined developing process was performed to form a resist pattern on the reflective mask blank.
Next, using this resist pattern as a mask, the alternately (five-period) laminated film of the Al film and the TaB film and the lower TaB film are dry-etched with a chlorine-based gas (Cl ₂ gas), and transferred to the absorber film. Was formed.
Further, the resist pattern remaining on the absorber film pattern was removed with hot sulfuric acid to obtain a reflective mask of this example.

  A final check of the obtained reflective mask was performed. As a result, it was confirmed that a pattern of the DRAM hp 10 nm generation in the semiconductor design rule was formed as designed.

As described above, in the reflective mask blank of the present embodiment and the reflective mask manufactured using the reflective mask blank, the EUV light reflectance with respect to the absorber film can be suppressed to 2% or less. It was confirmed that a lower reflectance (2% or less) for EUV light was obtained with a thinner absorber film thickness, and that a thinner absorber film could be realized.
When a pattern is transferred onto a semiconductor substrate by EUV light using the obtained reflective mask of the present embodiment, a semiconductor device of DRAM hp 10 nm generation according to the semiconductor design rule can be manufactured.

(Example 2)
A CrN conductive film was formed in the same manner as in Example 1 on the main surface of the glass substrate for a reflective mask blank prepared in the same manner as in Example 1 on the side opposite to the side on which the transfer pattern was formed.
Next, the glass substrate with the conductive film is set in an ion beam sputtering apparatus, and a multilayer reflective film, a protective film, and an absorber are formed on the main surface of the glass substrate on which a transfer pattern is formed as follows. The film was formed continuously.

First, a multilayer reflective film composed of an alternately laminated film of a Si film and a Mo film as in Example 1 was formed on a substrate.
Thereafter, a protective film composed of a laminated film of a Si film and a RuNb film was formed on the multilayer reflective film in the same manner as in Example 1.

  Here, a sample prepared in the same manner as described above for reflectance measurement was taken out of the apparatus, and the reflectance of 13.5 nm EUV light was measured at an incident angle of 6.0 degrees with respect to the multilayer reflective film having the protective film. As a result, the reflectance was 65.3%.

Next, an absorber film was formed on the protective film by ion beam sputtering as follows.
First, using a TaB target (Ta: B = 90: 10 atomic% ratio), a TaB film of a phase control layer was formed to a thickness of 4.0 nm. Subsequently, using a Si (amorphous) target and a TaB target (Ta: B = 90: 10 atomic%), a Si film of a high refractive index material layer is formed to a thickness of 2.7 nm, and then a low refractive index material layer is formed. A TaB film having a thickness of 4.4 nm was formed, and one cycle of the TaB film was formed. In the same manner, six cycles were stacked to form an absorber film including an alternately stacked film of a Si film and a TaB film.
As described above, the reflective mask blank of this example was manufactured.
The extinction coefficient k of the TaB film of the phase control layer at a wavelength of 13.5 nm is 0.03, the refractive index n of the Si film of the high refractive index material layer is 1.00, and the extinction coefficient k is 0.002. The refractive index n of the TaB film of the low refractive index material layer is 0.95, and the extinction coefficient k is 0.03.

When the reflectance of this reflective mask blank was measured with EUV light of 13.5 nm at an incident angle of 6.0 degrees, the reflectance was 1.6%.
According to the reflective mask blank of the present example, the total thickness of the absorber is 46.6 nm, which is significantly larger than the total thickness of the absorber of 70 nm in the reflective mask blank of the comparative example described later. It is possible to reduce the thickness.

Next, using this reflective mask blank, a reflective mask for EUV exposure having a pattern of the DRAM hp 10 nm generation in the semiconductor design rule was manufactured as follows.
First, a resist film for electron beam lithography was formed on the reflective mask blank, and a predetermined pattern was drawn using an electron beam lithography machine. After the drawing, a predetermined developing process was performed to form a resist pattern on the reflective mask blank.
Next, using this resist pattern as a mask, dry etching is performed on the alternating film (six periods) of the Si film and the TaB film and the lower TaB film with a fluorine-based gas (CF ₄ gas) to transfer the transfer pattern to the absorber film. Was formed.
Further, the resist pattern remaining on the absorber film pattern was removed with hot sulfuric acid to obtain a reflective mask of this example.

  A final check of the obtained reflective mask was performed. As a result, it was confirmed that a pattern of the DRAM hp 10 nm generation in the semiconductor design rule was formed as designed.

As described above, in the reflective mask blank of the present embodiment and the reflective mask manufactured using the reflective mask blank, the EUV light reflectance with respect to the absorber film can be suppressed to 2% or less. It was confirmed that a lower reflectance (2% or less) for EUV light was obtained with a thinner absorber film thickness, and that a thinner absorber film could be realized.
When a pattern is transferred onto a semiconductor substrate by EUV light using the obtained reflective mask of the present embodiment, a semiconductor device of DRAM hp 10 nm generation according to the semiconductor design rule can be manufactured.

(Example 3)
A CrN conductive film was formed in the same manner as in Example 1 on the main surface of the glass substrate for a reflective mask blank prepared in the same manner as in Example 1 on the side opposite to the side on which the transfer pattern was formed.
Next, the glass substrate with the conductive film is set in an ion beam sputtering apparatus, and a multilayer reflective film, a protective film, and an absorber are formed on the main surface of the glass substrate on which a transfer pattern is formed as follows. The film was formed continuously.

First, a multilayer reflective film composed of an alternately laminated film of a Si film and a Mo film as in Example 1 was formed on a substrate.
Thereafter, a protective film composed of a laminated film of a Si film and a RuNb film was formed on the multilayer reflective film in the same manner as in Example 1.

  Here, a sample prepared in the same manner as described above for reflectance measurement was taken out of the apparatus, and the reflectance of 13.5 nm EUV light was measured at an incident angle of 6.0 degrees with respect to the multilayer reflective film having the protective film. As a result, the reflectance was 65.3%.

Next, an absorber film was formed on the protective film by ion beam sputtering as follows.
First, a W film of 4.2 nm was formed as a phase control layer using a W (tungsten) target. Subsequently, using a Si (amorphous) target and a W (tungsten) target, a Si film of a high refractive index material layer is formed to a thickness of 2.5 nm, and a W film of a low refractive index material layer is formed to a thickness of 4.7 nm. This was defined as one cycle, and four cycles were similarly laminated to form an absorber film composed of alternately laminated films of a Si film and a W film.
As described above, the reflective mask blank of this example was manufactured.
The extinction coefficient k of the W film of the phase control layer at a wavelength of 13.5 nm is 0.04, the refractive index n of the Si film of the high refractive index material layer is 1.00, and the extinction coefficient k is 0.002. The refractive index n of the W film of the low refractive index material layer is 0.93, and the extinction coefficient k is 0.04.

When the reflectance of this reflective mask blank was measured with EUV light of 13.5 nm at an incident angle of 6.0 degrees, the reflectance was 1.6%.
According to the reflective mask blank of the present example, the total thickness of the absorber is 33.0 nm, which is significantly larger than the total thickness of the absorber of 70 nm in the reflective mask blank of the comparative example described later. It is possible to reduce the thickness.

Next, using this reflective mask blank, a reflective mask for EUV exposure having a pattern of the DRAM hp 10 nm generation in the semiconductor design rule was manufactured as follows.
First, a resist film for electron beam lithography was formed on the reflective mask blank, and a predetermined pattern was drawn using an electron beam lithography machine. After the drawing, a predetermined developing process was performed to form a resist pattern on the reflective mask blank.
Next, using this resist pattern as a mask, the mixed film of chlorine-based gas (SF ₆ ) and oxygen is used to dry-etch the alternately (four-period) stacked film of the Si film and the W film and the lower W film, thereby absorbing the film. A transfer pattern was formed on the body film.
Further, the resist pattern remaining on the absorber film pattern was removed with hot sulfuric acid to obtain a reflective mask of this example.

  A final check of the obtained reflective mask was performed. As a result, it was confirmed that a pattern of the DRAM hp 10 nm generation in the semiconductor design rule was formed as designed.

As described above, in the reflective mask blank of the present embodiment and the reflective mask manufactured using the reflective mask blank, the EUV light reflectance with respect to the absorber film can be suppressed to 2% or less. It was confirmed that a lower reflectance (2% or less) for EUV light was obtained with a thinner absorber film thickness, and that a thinner absorber film could be realized.
When a pattern is transferred onto a semiconductor substrate by EUV light using the obtained reflective mask of the present embodiment, a semiconductor device of DRAM hp 10 nm generation according to the semiconductor design rule can be manufactured.

(Comparative Example 1)
A CrN conductive film was formed in the same manner as in Example 1 on the main surface of the glass substrate for a reflective mask blank prepared in the same manner as in Example 1 on the side opposite to the side on which the transfer pattern was formed.
Next, the glass substrate with a conductive film was set in an ion beam sputtering apparatus, and a multilayer reflective film and a protective film were continuously formed on the main surface of the glass substrate on the side where a transfer pattern was formed.

First, a multilayer reflective film composed of an alternately laminated film of a Si film and a Mo film as in Example 1 was formed on a substrate.
Subsequently, a protective film composed of a laminated film of a Si film and a RuNb film was formed on the multilayer reflective film in the same manner as in Example 1.

  Here, the substrate with the multilayer reflection film was taken out of the apparatus, and the reflectance of the multilayer reflection film having the protective film was measured at an incident angle of 6.0 ° with 13.5 nm EUV light. 3%.

Next, a TaBSiN film (thickness: 60 nm, Ta: B: Si: N = 70: 3: 10: 1017 atomic%) as an absorber film is formed on the protective film of the substrate with the multilayer reflective film manufactured as described above. Ratio) and a TaBSiON film (thickness: 10 nm, Ta: B: Si: O: N = 40: 3: 10: 37: 10 atomic% ratio) were formed by DC magnetron sputtering. The total thickness of the absorber is 70 nm.
As described above, the reflective mask blank of this comparative example was manufactured.
When the reflectance of this reflective mask blank was measured with an EUV light of 13.5 nm at an incident angle of 6.0 degrees, the reflectance was 0.4%.

Next, using this reflective mask blank, a reflective mask for EUV exposure having a pattern of the DRAM hp 10 nm generation in the semiconductor design rule was manufactured as follows.
First, a resist film for electron beam lithography was formed on the reflective mask blank, and a predetermined pattern was drawn using an electron beam lithography machine. After the drawing, a predetermined developing process was performed to form a resist pattern on the reflective mask blank.
Next, using the resist pattern as a mask, the upper TaBSiON film is dry-etched with a fluorine-based gas (CF ₄ gas), and the lower TaBSiN film is dry-etched with a chlorine-based gas (Cl ₂ gas), thereby forming a transfer pattern on the absorber film. Formed.
Further, the resist pattern remaining on the absorber film pattern was removed with hot sulfuric acid to obtain a reflective mask of this comparative example.

A final check of the obtained reflective mask was performed. As a result, it was confirmed that a pattern of the DRAM hp 10 nm generation in the semiconductor design rule was formed as designed.
However, when a pattern is transferred to a semiconductor substrate by EUV light using the obtained reflective mask of the present comparative example, the thickness of the absorber film is as large as 70 nm. May cause defects.

DESCRIPTION OF SYMBOLS 1 Substrate 2 Multilayer reflective film 21 Si layer 22 Mo layer 3 Protective film 4 Absorber film 41 Phase control layer 43 Low refractive index material layer 42 High refractive index material layer 10 Reflective mask blank 20 Reflective mask

Claims (14)

A reflective mask blank comprising a multilayer reflective film that reflects EUV light on a substrate, a protective film, and an absorber film in this order,
The absorber film is composed of a laminated film obtained by alternately laminating a high refractive index material layer and a low refractive index material layer,
The high refractive index material layer is at least one metal selected from Si, Al, Cu, Zn, Te, Ge, Mg, Hf, and Zr, or an alloy containing the metal, and an oxide of the metal or alloy, A material containing nitride, carbide, oxynitride, oxycarbide, nitrided carbide, oxynitride carbide, boride, boride oxide, boride nitride or boride oxynitride,
The low-refractive-index material layer includes at least one metal selected from Ta, Cr, Ag, Pd, W, Fe, Pt, Au, Co, Ir, Ni, and Sn, or an alloy containing the metal, and the metal or an oxide of an alloy, nitride, carbide, oxynitride, carbide oxide, carbide nitride, carbide oxide nitride, borides, boride oxide, Ri Do from a material comprising a boride nitride or boride oxynitride,
A reflective mask blank, wherein the reflectivity of EUV light to the absorber film is 2% or less . 2. The reflective mask blank according to claim 1, wherein the laminated film has two or more periods when the laminated structure of the high refractive index material layer and the low refractive index material layer is one period. 3. The absorber film further includes a phase control layer, and the high refractive index material layer and the low refractive index material layer of the laminated film are provided in this order on the phase control layer. 3. The reflective mask blank according to 1 or 2 . The phase control layer is formed of at least one metal selected from Ta, Cr, Ag, Pd, W, Fe, Pt, Au, Co, Ir, Ni, and Sn, or an alloy containing the metal, and the metal or alloy. Oxide, nitride, carbide, oxynitride, oxycarbide, nitrided carbide, oxynitride carbide, boride, boride oxide, boride nitride or boride oxynitride The reflective mask blank according to claim 3 , wherein The reflective mask blank according to claim 3 or 4, characterized in that said phase control layer and the low refractive index material layer is made of the same material. The phase control layer is incident on the reflective mask blank, and each of the low-refractive-index layer and the high-refractive-index layer of an alternately stacked film of a low-refractive-index layer and a high-refractive-index layer constituting the multilayer reflective film. The reflection light at the interface and the reflection light (A) due to the reflection at the surface of the protective film, and each of the phase control layer, the high refractive index material layer, and the low refractive index material layer constituting the absorber film The reflection type according to any one of claims 3 to 5 , wherein the film thickness is set so that the phase with respect to the reflected light (B) due to reflection at the interface differs by 180 ° ± 10 °. Mask blank. A method for manufacturing a reflective mask, comprising patterning the absorber film in the reflective mask blank according to any one of claims 1 to 6 . A reflective mask including a multilayer reflective film that reflects EUV light on a substrate, a protective film, and a transfer pattern formed of an absorber film in this order,
The absorber film is composed of a laminated film obtained by alternately laminating a high refractive index material layer and a low refractive index material layer,
The high refractive index material layer is at least one metal selected from Si, Al, Cu, Zn, Te, Ge, Mg, Hf, and Zr, or an alloy containing the metal, and an oxide of the metal or alloy, A material containing nitride, carbide, oxynitride, oxycarbide, nitrided carbide, oxynitride carbide, boride, boride oxide, boride nitride or boride oxynitride,
The low-refractive-index material layer includes at least one metal selected from Ta, Cr, Ag, Pd, W, Fe, Pt, Au, Co, Ir, Ni, and Sn, or an alloy containing the metal, and the metal or an oxide of an alloy, nitride, carbide, oxynitride, carbide oxide, carbide nitride, carbide oxide nitride, borides, boride oxide, Ri Do from a material comprising a boride nitride or boride oxynitride,
A reflective mask, wherein the reflectivity of EUV light to the absorber film is 2% or less . 9. The reflection mask according to claim 8 , wherein the laminated film has two or more periods when the laminated structure of the high-refractive-index material layer and the low-refractive-index material layer is one period. The absorber film further includes a phase control layer, and the high refractive index material layer and the low refractive index material layer of the laminated film are provided in this order on the phase control layer. 10. The reflective mask according to 8 or 9 . The phase control layer is formed of at least one metal selected from Ta, Cr, Ag, Pd, W, Fe, Pt, Au, Co, Ir, Ni, and Sn, or an alloy containing the metal, and the metal or alloy. Oxide, nitride, carbide, oxynitride, oxycarbide, nitrided carbide, oxynitride carbide, boride, boride oxide, boride nitride or boride oxynitride The reflective mask according to claim 10 . The reflective mask according to claim 10 or 11, characterized in that said phase control layer and the low refractive index material layer is made of the same material. The phase control layer is incident on the reflective mask, and each interface between the low-refractive-index layer and the high-refractive-index layer of an alternately laminated film of a low-refractive-index layer and a high-refractive-index layer constituting the multilayer reflective film. (A) due to reflection at the surface and reflection at the surface of the protective film, and respective interfaces between the phase control layer, the high refractive index material layer, and the low refractive index material layer constituting the absorber film. The reflection type mask according to any one of claims 10 to 12 , wherein the film thickness is set so that the phase with respect to the reflected light (B) due to reflection at the light source differs by 180 ° ± 10 °. . Reflective mask obtained by the production method according to claim 7, or a characterized in that it comprises the step of patterning on a semiconductor substrate using the reflective mask according to any one of claims 8 to 13 Semiconductor device manufacturing method.

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