JP2019049720A - Reflective mask blank, reflective mask, method for manufacturing the same, and method for manufacturing semiconductor device - Google Patents

Abstract

To provide a reflective mask blank that suppresses a reflectance of EUV light on an absorber film to be 2% or less and gives a low reflectance for EUV light with a smaller film thickness of the absorber film compared to conventional films.SOLUTION: A reflective mask blank 10 comprises, on a substrate 1: a multilayer reflection film 2 for reflecting EUV light; a protection film 3 for protecting the multilayer reflection film 2; and an absorber film 4 for absorbing EUV light. The absorber film 4 includes: a phase-control layer 41; and a laminate film formed by alternately stacking high-refraction index material layers 42 and low-refraction index material layers 43. The film thickness of the phase-control layer 41 is set in such a manner that the reflectance of EUV light on the absorber film is 2% or less caused by the difference in the phase between: reflection light (A) of the light incident to the reflective mask blank, then reflected on each interface of low-refraction index layers and high-refraction index layers constituting the multilayer reflection film and reflected on the surface of the protection film; and reflection light (B) of the light reflected on each interface of the phase-control layer, the high-refraction index material layers and the low-refraction index material layers constituting the absorber film.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a reflective mask blank which is an original plate for producing an exposure mask used for semiconductor device production and the like, a reflective mask and a method for producing the same, and a method for producing a semiconductor device.

  With the further demand for higher density and higher accuracy of ultra LSI devices in recent years, EUV lithography, which is an exposure technology using extreme ultraviolet (hereinafter referred to as “EUV”) light, is considered promising There is. Here, EUV light refers to light in a wavelength band of soft x-ray region or vacuum ultraviolet light region, and specifically, light having a wavelength of about 0.2 to 100 nm.

  In such a reflective mask, a multilayer reflective film that reflects exposure light is formed on a substrate, and an absorber film that absorbs exposure light is formed in a pattern on the multilayer reflective film. The light incident on the reflective mask mounted on the exposure device (pattern transfer device) is absorbed in a portion where the absorber film is present, and in the portion where the absorber film is not present, the light image reflected by the multilayer reflective film is a reflection optical system Transferred onto the semiconductor substrate.

In order to achieve high density and high precision of a semiconductor device by using such a reflective mask, the reflective region (the surface of the multilayer reflective film) in the reflective mask is higher than EUV light which is exposure light. It is required that a high contrast be obtained between an absorber film pattern having reflectivity and absorbing exposure light.
The multilayer reflective film is a multilayer film in which elements having different refractive indices are periodically stacked, and generally, a thin film of a heavy element or its compound and a thin film of a light element or its compound alternate 40 to 40 A multilayer film laminated for about 60 cycles is used. For example, as a multilayer reflective film for EUV light with a wavelength of 13 to 14 nm, a Mo / Si periodic laminated film in which Mo films and Si films are alternately laminated for about 40 cycles is preferably used.

As a reflective mask blank which is an original plate for manufacturing a reflective mask used in this EUV lithography, for example, a reflective 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 includes tantalum (Ta) and boron (B). 2.) A reflective mask blank for EUV lithography is disclosed which contains silicon (Si) and nitrogen (N) in predetermined proportions. In addition, in Patent Document 1, a low reflection layer for inspection light used for inspection of a mask pattern is formed on the above-mentioned absorber layer, and the low reflection layer is made of tantalum (Ta), boron (B), silicon ( Also disclosed is a reflective mask blank for EUV lithography that contains Si) and oxygen (O) at a predetermined content ratio.

  Further, in Patent Document 2 below, at least two types of substances having different optical constants are multi-layered on a reflective surface consisting of a multilayer reflective film in which at least two types of substances having different optical constants are alternately stacked at a predetermined film thickness. There is disclosed a reflection type mask provided with a non-reflection portion in which a multilayer antireflective film is alternately formed in a film shape alternately laminated with a film thickness different from a predetermined film thickness in the reflective film.

Patent No. 4867695 gazette Patent No. 2545905 gazette

  In the conventional reflective mask blank disclosed in Patent Document 1 as described above and the reflective mask manufactured from the reflective mask blank, the film thickness of the absorber layer is sufficient for the EUV light which is the exposure light. The thickness needs to be able to be absorbed, and usually a thickness of more than 60 nm has been required. Further, in the case of the laminated structure of the absorber layer and the low reflection layer, the thickness is further 70 nm or more.

  However, in the exposure apparatus in which the exposure light is incident on the reflective mask at a predetermined angle (approximately 6 degrees of incident angle), if the absorber layer pattern having a thickness of more than 60 nm is formed as described above, There is a serious problem that the reflection area is shadowed by the absorber layer pattern (shadowing), the image reflected by the reflection area does not match the patterning image, and the accuracy of the transfer pattern is degraded. In addition, in the formation of a narrow (for example, 20 nm or less) absorber pattern, the aspect ratio becomes high, and there is a possibility that the pattern becomes brittle and a defect occurs due to falling.

  On the other hand, in the reflective mask having the non-reflecting portion of the multilayer film disclosed in Patent Document 2, the exposure light reflectance in the non-reflecting portion can be suppressed to at most about 3%. In order to perform pattern transfer with high accuracy in EUV lithography, it is necessary to suppress the exposure light reflectance in the non-reflecting portion to, for example, 2% or less, which is difficult to realize with the reflective mask disclosed in Patent Document 2 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 peeled off, it is difficult to form a high-definition mask pattern, and process defects are likely to occur in the multilayer film of the non-reflecting portion.

  Therefore, an object of the present invention is, first, to provide a reflective mask blank and a reflective mask capable of suppressing the reflectance of EUV light to the absorber film to 2% or less, and secondly, conventionally A reflective mask blank and a reflective mask capable of obtaining low reflectance to EUV light with a thin absorber film thickness, and thirdly, a reflection using such a reflective mask blank A method of manufacturing a mold mask and a method of manufacturing a semiconductor device.

MEANS TO SOLVE THE PROBLEM As a result of earnestly researching in order to solve the said subject, this inventor completed this invention which has the following structures.
(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 It is a mask blank, and the multilayer reflective film has a structure in which a multilayer structure is formed by laminating a low refractive index layer and a high refractive index layer on a plurality of cycles with one cycle, and the absorber film is A phase control layer, and a laminated film in which high refractive index material layers and low refractive index material layers are alternately laminated on the phase control layer, and the light is incident on the reflective mask blank; Reflected light (A) by reflection at each interface of the low refractive index layer and the high refractive index layer constituting the reflective film, and reflection on the surface of the protective film, and the phase control constituting the absorber film A layer, the high refractive index material layer, and the low refractive index material layer The film thickness of the phase control layer is set so that the reflectivity of the EUV light to the absorber film is 2% or less by the difference in the phase of the reflected light (B) due to the 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 that reflects EUV light on a substrate, and an etching prevention 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 formed by laminating a plurality of periods as a period, and the absorber film includes a phase control layer, and a laminated film in which high refractive index material layers and low refractive index material layers are alternately laminated on the phase control layer. The light is incident on the reflective mask blank, and is reflected by each interface of the low refractive index layer and the high refractive index layer constituting the multilayer reflective film, and by the reflection on the surface of the protective film. Reflected light (A) and the phase constituting the absorber The reflectivity of the EUV light to the absorber film is 2% by the difference in the phase of the reflected light (B) by reflection at each interface with the control layer, the high refractive index material layer, and the low refractive index material layer. By setting the film thickness of the phase control layer so as to be as follows, the reflectance of EUV light to the absorber film can be suppressed to 2% or less, and the contrast with the reflective region is enhanced. High-definition pattern transfer can be realized using a reflective mask manufactured using the inventive reflective mask blank.
Further, according to the configuration 1, since a low reflectance (for example, 2% or less) to EUV light can be obtained with the film thickness of the absorber film thinner than before, the absorber film can be thinner than before. Various problems due to conventional shadowing and high aspect ratio can be solved.

(Configuration 2)
The film thickness is set such that the phase control layer is incident on the reflective mask blank and the phase of the reflected light (A) and the reflected light (B) differ by 180 ° ± 10 °. The reflective mask blank according to Configuration 1, characterized in that
As in the 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) differ by 180 ° ± 10 °. By setting the film thickness, the light transmitted through the absorber film and reflected light from the multilayer reflection film is canceled by the light reflected from the absorber film in the opposite phase to this, and the light reflected in the EUV light absorption region is suppressed. As a result, it is possible to suppress the reflectance of EUV light to the absorber film to 2% or less, and to obtain a low reflectance to EUV light with a thinner absorber film thickness than before. Can.

(Configuration 3)
The reflective mask blank according to Configuration 1 or 2, wherein the phase control layer is 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 in the prior art, the phase control layer has an extinction coefficient k of 0. It is preferable to select a material of 03 or more.

(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 and an extinction coefficient k (low) of 0.03 or more, and the absorber 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. A reflective mask blank according to any one of the configurations 1 to 3, characterized in that it satisfies the condition indicated by.
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 in the prior art, a low refractive index material layer constituting the absorber film and In the high refractive index material layer, each refractive index and extinction coefficient preferably satisfy the condition of the above-mentioned configuration 4.

(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 It is a mask blank, and the multilayer reflective film has a structure in which a multilayer structure is formed by laminating a low refractive index layer and a high refractive index layer on a plurality of cycles with one cycle, and the absorber film is And a laminated film formed by alternately laminating a high refractive index material layer and a low refractive index material layer on the phase control layer, and the film 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 has a refractive index n (low) at a wavelength of 13.5 nm of 0. .95 or less, extinction coefficient k (low) is 0.03 or more, and the absorber 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
And the film thickness of the phase control layer is set so that the reflectance of EUV light to the absorber film is less than or equal to a predetermined reflectance. Mold mask blank.

As described in 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 prevention 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 formed by laminating a plurality of periods as a period, and the absorber film is formed by alternately laminating a high refractive index material layer and a low refractive index material layer on the phase control layer and the phase control layer. And the film thickness of the absorber film is 60 nm or less, and 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 The material layer has a refractive index n (low) of 0 at a wavelength of 13.5 nm. 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
The thickness of the phase control layer is set so that the reflectance of EUV light to the absorber film is less than or equal to a predetermined reflectance, so the material is thinner than in the prior art. Since a low reflectance (for example, 2% or less) to EUV light can be obtained with the film thickness (60 nm or less) of the absorber film, the absorber film can be thinner than in the past, and conventional shadowing and high aspect A reflective mask blank is obtained which can eliminate various problems due to the ratio.

(Configuration 6)
The reflective mask blank according to Configuration 5, wherein a thickness of the phase control layer is set such that a reflectance of EUV light with respect to the absorber film is 2% or less.
As described in Configuration 6, the film thickness of the phase control layer is set such that the reflectance of EUV light to the absorber film is 2% or less, thereby reflecting the EUV light to the absorber film. Rate can be suppressed to 2% or less, contrast with the reflective region is enhanced, and high-definition pattern transfer is realized using the reflective mask manufactured using the reflective mask blank of the present invention. it can.

(Configuration 7)
A method of manufacturing a reflective mask, comprising: patterning the absorber film in the reflective mask blank according to any one of Configurations 1 to 6.
By producing a reflective mask using the reflective mask blank of the present invention as in the above-mentioned configuration 7, it is possible to suppress the reflectance of EUV light to the absorber film to 2% or less, and it is thinner than conventional. A reflective mask can be obtained in which a low reflectance to EUV light can be obtained by the film thickness of the absorber film.

(Configuration 8)
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, a transfer pattern comprising an absorber film on the protective film The multilayer reflective film has a multi-layered structure in which a laminated structure in which a low refractive index layer and a high refractive index layer are laminated is laminated on a plurality of cycles on the substrate, and the absorption is the reflective mask. 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 light enters the reflective mask. Reflected light (A) due to reflection at each interface of the low refractive index layer and the high refractive index layer constituting the multilayer reflective film, and reflection on the surface of the protective film, and the phase constituting the absorber A control layer, the high refractive index material layer, and the low refractive index material layer The film thickness of the phase control layer is set such that the reflectance of EUV light to the absorber film is 2% or less by making the phase of the reflected light (B) by reflection at each interface different. Reflective mask characterized by

As described in Configuration 8, the reflective mask of the present invention has a multilayer reflective film for reflecting EUV light on a substrate, and a protection 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 of 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 formed by alternately laminating a high refractive index material layer and a low refractive index material layer on the phase control layer and the phase control layer. And a film, which is incident on the reflective mask, and reflects at each interface between the low refractive index layer and the high refractive index layer that constitute the multilayer reflective film, and reflects on the surface of the protective film Reflected light (A), and the phase control constituting the absorber And the phase of the reflected light (B) by reflection at each interface with the high refractive index material layer and the low refractive index material layer is different, so that the reflectivity of the EUV light to the absorber film is 2% or less As described above, by setting the film thickness of the phase control, the reflectance of EUV light to the absorber film can be suppressed to 2% or less, the contrast with the reflection region is enhanced, and the reflection of the present invention is achieved. A high definition pattern transfer can be realized using a mold mask.
Further, according to the eighth aspect, since the reflective mask of the present invention can obtain a low reflectance (for example, 2% or less) to EUV light with a thinner absorber film thickness than in the prior art, the absorber film is The film thickness can be reduced, and various problems caused by the conventional shadowing and the high aspect ratio can be solved.

(Configuration 9)
The film thickness of the phase control layer is set such that the phase of the reflected light (A) and the reflected light (B) is different by 180 ° ± 10 ° upon entering the reflective mask. The reflective mask according to Configuration 8, which is characterized by the following.
As in the configuration 9, the phase control layer is a film so that the phase of the reflected light (A) and the reflected light (B) is different by 180 ° ± 10 ° when entering the reflective mask. By setting the thickness, the light transmitted through the absorber film is canceled by the light reflected from the absorber film having a phase opposite to that of the multilayer reflection film, and the light reflected in the EUV light absorption region is suppressed. As a result, the reflectance of EUV light to the absorber film can be suppressed to 2% or less, and furthermore, a low reflectance to EUV light can be obtained with a thinner absorber film thickness than before. it can.

(Configuration 10)
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, a transfer pattern comprising an absorber film on the protective film The multilayer reflective film has a multi-layered structure in which a laminated structure in which a low refractive index layer and a high refractive index layer are laminated is laminated on a plurality of cycles on the substrate, and the absorption is the reflective mask. The body film is composed of a phase control layer, and a laminated film formed by alternately laminating a high refractive index material layer and a low refractive index material layer on the phase control layer, and the film thickness of the absorber film Is 60 nm or less, the phase control layer is a material whose extinction coefficient k at a wavelength of 13.5 nm is 0.03 or more, and the low refractive index material layer has a refractive index n (low) at a wavelength of 13.5 nm. ) Is 0.95 or less, 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
The reflectance of the EUV light in the transfer pattern formation region can be recognized with respect to the reflectance of the EUV light in the reflection region where the transfer pattern is exposed. The film thickness of the said phase control layer is set so that there may be a difference in extent, The reflection type mask characterized by the above-mentioned.

As in the configuration 10, the reflective mask of the present invention has a multilayer reflective film that reflects EUV light on a substrate, and a protection having an etching prevention function for protecting the multilayer reflective film on the multilayer reflective film. A reflective mask comprising a film and a transfer pattern of 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 formed by alternately laminating a high refractive index material layer and a low refractive index material layer on the phase control layer and the phase control layer. A film thickness of the absorber film is 60 nm or less, and the phase control layer is a material having an extinction coefficient k at a wavelength of 13.5 nm of 0.03 or more, The refractive index material layer has a refractive index n (low) at a wavelength of 13.5 nm. And 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
The reflectance of the EUV light in the transfer pattern formation region is the reflectance of the EUV light in the reflection region where the transfer pattern is exposed (that is, the region without the transfer pattern). On the other hand, since the film thickness of the phase control layer is set to have a difference to the extent that the transfer pattern can be recognized, the film thickness of the absorber film (60 nm or less) thinner than the conventional one is lower for EUV light Since a reflectance (for example, 2% or less) can be obtained, the absorber film can be thinner than in the past, and a reflective 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 a thickness of the phase control layer is set such that a reflectance of EUV light with respect to the absorber film is 2% or less.
As in the configuration 11, the film thickness of the phase control layer is set such that the reflectance of EUV light to the absorber film is 2% or less, whereby reflection of EUV light to the absorber film is achieved. Rate can be suppressed to 2% or less, so that the contrast between the transfer pattern formation region and the reflection region where the transfer pattern is exposed can be enhanced, and high-definition pattern transfer can be realized using a reflective mask. it can.

(Configuration 12)
According to a seventh aspect of the present invention, there is provided a semiconductor device including a step of forming a pattern on a semiconductor substrate using the reflective mask obtained by the manufacturing method according to the seventh aspect or the reflective mask according to any of the eighth to eleventh aspects. Production method.
As described in Configuration 12, by forming a pattern on a semiconductor substrate by pattern transfer using the reflective mask of the present invention to manufacture a semiconductor device, 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.
Moreover, according to the present invention, it is possible to obtain a reflective mask blank and a reflective mask that can obtain low reflectance to EUV light with a thinner absorber film than conventional.
In addition, 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 film thickness of the absorber film thinner than before can be obtained. Thus, it is possible to obtain a reflective mask that can obtain low reflectance to 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.

It is sectional drawing which shows the laminated constitution of one Embodiment of the reflection type mask blank which concerns on this invention. It is sectional drawing which shows the detailed laminated constitution of one Embodiment of the reflection type mask blank which concerns on this invention. It is sectional drawing which shows the laminated constitution of the reflection type mask which concerns on this invention.

Hereinafter, the present invention will be described in detail by way of embodiments.
[Reflective mask blank]
First, a reflective mask blank according to the present invention will be described.
FIG. 1 is a cross-sectional view showing a layer structure of an embodiment of a reflective mask blank according to the present invention, and a multilayer reflective film 2 for reflecting EUV light as exposure light on a substrate 1 and the multilayer reflective film 2 The reflective mask blank 10 of the structure provided with the protective film 3 for protecting a film | membrane, and the absorber film 4 for transfer pattern formation which absorbs EUV light is shown.
Although not shown, the back surface conductive film can be provided on the side opposite to the side on which the multilayer reflective film or the like of the substrate 1 is formed.

In the case of EUV exposure, the substrate 1 preferably has a low thermal expansion coefficient within the range of 0 ± 5 ppb / ° C. in order to prevent distortion of the pattern due to heat at the time of exposure. As a raw material which has, for example, SiO ₂ —TiO ₂ based glass, multicomponent glass ceramics, etc. can be used.

  The main surface on the side on which the transfer pattern of the substrate 1 is formed is processed so as to have high flatness from the viewpoint of obtaining at least pattern transfer accuracy and position accuracy. For example, in the case of EUV exposure, the flatness is preferably 0.1 μm or less, more preferably 0.05 μm or less, particularly preferably, in a region of 132 mm × 132 mm on the main surface on the side where the transfer pattern of the substrate is formed. Is less than 0.03 μm. Further, 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 the flatness is 1 μm or less, more preferably 0 in a 142 mm × 142 mm region. 0.5 μm or less, particularly preferably 0.03 μm or less.

  In the case of EUV exposure, the surface smoothness required of the substrate 1 is 0.1 nm or less in terms of root mean square roughness (RMS) of the surface roughness of the main surface on which the transfer pattern of the substrate is formed. Is preferred.

  The multilayer reflective film 2 is a multilayer film in which elements having different refractive indices are periodically stacked, and in general, a thin film of a heavy element which is a low refractive index material or a compound thereof (low refractive index layer) A multilayer film is used in which thin films (high refractive index layers) of light elements or compounds thereof that are high refractive index materials are alternately stacked for about 40 to 60 cycles. The multilayer reflective film 2 may have a laminated structure in which a high refractive index layer and a low refractive index layer are laminated in this order from the substrate side in a plurality of periods, and the low refractive index layer and the high refractive index layer may be laminated from the substrate side. A plurality of cycles may be stacked with one cycle being a stacked structure in which the layers are stacked in this order. As the low refractive index material, an element selected from Mo, Ru, Rh, Pt, or an alloy thereof is used, and as the high refractive index material, Si or a Si compound is used. For example, as a multilayer reflective film for EUV light with a wavelength of 13 to 14 nm, preferably, 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, for example, by forming each layer by ion beam sputtering. In the case of the above-described Mo / Si periodic multilayer film, a Si film of about several nm in thickness is first formed by using an Si target by, for example, ion beam sputtering method, and then a several nm thick is formed by using Mo target. An Mo film is formed, and 40 to 60 cycles are laminated with this cycle as one cycle.

  In the present embodiment, a protective film 3 (also referred to as a capping layer or a buffer layer) may be provided on the multilayer reflective film 2 to protect the multilayer reflective film during patterning or pattern correction of the absorber film. ) Is provided. As a material of such a protective film 3, for example, in addition to silicon, ruthenium and a ruthenium compound containing one or more elements of niobium, zirconium and rhodium in ruthenium are preferably used. Besides this, chromium-based materials may be used. The protective film 3 may be a laminated film of the above-described materials.

When the protective film 3 is ruthenium or a ruthenium compound, the film thickness thereof is preferably, for example, in the range of 1 nm to 5 nm. If the film thickness is smaller than 1 nm, the function of protecting the multilayer reflective film may not be sufficiently obtained. On the other hand, if the film thickness is larger than 5 nm, there is a possibility that the reflectance of the multilayer reflective film having a protective film to be a reflective region of the mask is lowered.
When the protective film is a laminated film of silicon and ruthenium or a ruthenium compound, the film thickness of the laminated film is preferably, for example, in the range of 6.5 nm to 7 nm.

  The method for forming the protective film 3 is not particularly limited, and usually, ion beam sputtering, magnetron sputtering, etc. is applied, but from the viewpoint of defect reduction, the multilayer reflective film 2 and the protective film 3 are continuous. It is desirable to form a film by ion beam sputtering. In the case of performing a different film formation method after forming the multilayer reflective film 2, the substrate is once exposed to the atmosphere, so there is a possibility of dust generation.

FIG. 2 is a cross-sectional view showing a detailed layer configuration of an 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 is a multilayer in which an Si film 21 as a high refractive index layer and an Mo film 22 as a low refractive index layer are alternately stacked 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.

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

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

In the reflective mask blank of the present invention, as described above, the absorber film 4 alternately has the phase control layer 41 and the high refractive index material layer 42 and the low refractive index material layer 43 on the phase control layer 41. Each of the Mo film 22 as a low refractive index layer and the Si film 21 as the high refractive index layer, which is configured as a laminated laminated film, is incident on the reflective mask blank 10 and constitutes the multilayer reflective film 2. Reflected light (A) by reflection on the interface and reflection on the surface of the protective film 3, the phase control layer 41 constituting the absorber film 4, the high refractive index material layer 42, and the low refraction Film of the phase control layer 41 so that the reflectance of the EUV light to the absorber film becomes 2% or less by the difference in the phase of the reflected light (B) due to reflection at each interface with the index material layer 43 By setting the thickness, E to the absorber film The reflectance of V light can be suppressed to 2% or less, the contrast with the reflective area is enhanced, and high-definition pattern transfer is performed using a reflective mask manufactured using the reflective mask blank of the present invention. It can be realized.
In addition, in the reflective mask blank of the present invention, a low reflectance (for example, 2% or less) to EUV light can be obtained with a thinner absorber film thickness than conventional. 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-mentioned prior art can be solved.

  In order to more effectively exhibit the above-described effects according to 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) However, it is desirable that the film thickness be set so as to differ by 180 ° ± 10 °.

  In the embodiment of the present invention shown in FIG. 2, the absorber film 4 is composed of 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. There is. In order to obtain the effect of thinning the absorber film 4, it is preferable that the material of the phase control layer 41 be a material whose extinction coefficient k at a wavelength of 13.5 nm is 0.03 or more. Preferably, for the material of the phase control layer 41, the extinction coefficient k at a wavelength of 13.5 nm is preferably 0.03 or more and 0.1 or less. Here, the phase control layer 41 in the lowermost layer of the absorber film 4 and the low refractive index material layers 43 in the upper layer may be the same material or different materials. The film thicknesses of the phase control layer 41 and the low refractive index material layer 43 may be the same or different. In addition, it is preferable that the alternately laminated film 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 cycle length. Although the effect of reducing the thickness of the absorber film 4 and the reduction effect of the reflectance decrease, the absorber film 4, the phase control layer 41, and the lower value thereof are reduced without departing from the effects of the present invention. You may comprise by the alternately laminated film of the refractive index material layer 43 and the high refractive index material layer 42. FIG. The phase control layer 41 reflects the Mo film of the low refractive index layer constituting the multilayer reflective film 2 and the Si film of the high refractive index layer at each interface, and reflects the surface of the protective film 3. The phase of the reflected light (B) by reflection at each interface between the reflected light (A) by the phase difference with the phase control layer 41 constituting the absorber film, the high refractive index material layer 42, and the low refractive index material layer 43 is different. As such, it is a layer having 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 each of the phase control layer 41, the high refractive index material layer 42, and the low refractive index material layer 43 that constitutes the absorber film 4. Reflected light B by reflection at the interface, reflection at each interface of the Mo film of the low refractive index layer and the Si film of the high refractive index layer which transmits the absorber film 4 and constitutes the multilayer reflective film 2, and the above When the phase with the reflected light A due to the reflection on the surface of the protective film is different by 180 ° ± 10 °, the light is transmitted through the absorber film 4 and the reflected light A from the multilayer reflective film 2 is an absorber film of the opposite phase to this. The reflected light B from 4 can be canceled to suppress the reflected light in the EUV light absorption region. As a result, the reflectance of EUV light to the absorber film 4 (the EUV light absorption region) can be suppressed to 2% or less. Moreover, by setting the absorber film 4 to the multilayer film structure of the present invention, it is possible to obtain a low reflectance for EUV light with a film thickness of the absorber film thinner than before.
In the present invention, the phase difference between the EUV light (reflected light B) reflected by the absorber film 4 and the EUV light (reflected light A) transmitted through the absorber film 4 and reflected by the multilayer reflection 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 1% or less, more preferably 0.5% or less, and most preferably 0.2% or less.
Further, in the reflective mask blank of the present invention, the film thickness of the absorber film can be reduced, and is preferably 60 nm or less, for example. More preferably, it is 50 nm or less, more preferably 45 nm or less, and most preferably 40 nm or less.

Each refractive index 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 in order to satisfy the above-described EUV light reflectance and the film thickness of the absorber film; 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 more than. 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 value of the refractive index n (low) at a wavelength of 13.5 nm is 0.83 or more, and the upper limit value of the extinction coefficient k (low) is 0.1 or less preferable.

Further, 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 indicated 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-mentioned absorber film to 2% or less and making the absorber film thinner than in the prior art, a low refractive index material layer constituting the absorber film and In the high refractive index material layer, each refractive index and extinction coefficient preferably satisfy the above conditions.

That is, the absorber film 4 is configured as 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 phase control layer 41, and The film thickness of the absorber film 4 is, for example, 60 nm or less, and the phase control layer 41 is a material whose extinction coefficient k at a wavelength of 13.5 nm is 0.03 or more, 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 .5 nm is
n (high) ≧ 1.46 × n (low) −0.41
The film thickness of the phase control layer 41 is set so that the reflectance of the EUV light to the absorber film 4 is less than or equal to a predetermined reflectance. Since a low reflectance (for example, 2% or less) to EUV light can be obtained with a thin absorber film thickness (60 nm or less), the absorber film can be thinner than in the prior art, and conventional shadowing and A reflective mask blank is obtained which can eliminate various problems due to the high aspect ratio.

As materials of the phase control layer and the low refractive index material layer applicable to the absorber film of the reflective mask blank of the present invention, for example, Ta, Cr, Ag, Pd, W, Fe, Pt, Au, Co , Ir, Ni, Sn, or an alloy containing the metal, the metal, an oxide of the alloy, a nitride, a carbide, an oxynitride, an oxidized carbide, an oxidized carbide, an oxidized nitride carbide, Preferred examples include borides, boride oxides, boride nitrides, boride oxynitrides and the like.
The material of the high refractive index material layer applicable to the absorber film of the reflective mask blank of the present invention is, for example, at least one selected from Si, Al, Cu, Zn, Te, Ge, Mg, Hf, and Zr. 1 type of metal, or an alloy containing the metal, the metal, oxide of the alloy, nitride, carbide, oxynitride, carbide of carbide, carbide of carbonitride, carbide of carbonitride of carbide, boride, boride oxide, boride Preferred are nitrides, boron oxynitrides and the like.
When the boride, boride oxide, boride nitride, boride oxide nitride of the above-described metal or metal-containing alloy is employed in the phase control layer, the low refractive index material layer, and the high refractive index material layer, Since the crystal structure has an amorphous structure, the surface of the absorber film can be smoothed, and effects such as making it easier to detect fatal defects in defect inspection can be obtained.

  Further, the combination of the materials of the low refractive index material layer and the high refractive index material layer included in the preferable range of the refractive index n and the extinction coefficient k is as shown in Table 1 below.

  In the above Table 1, “○” is a preferable material in which the film thickness of the absorber film is 50 nm or less in 3 to 6 cycles, where the laminated structure of the high refractive index material layer and the low refractive index material layer is one cycle. “◎” is a combination of a high refractive index material layer and a low refractive index material layer in one cycle, the film thickness of the absorber film is 20 nm or less, and the reflectance is 2% in two cycles It is the combination of the further more preferable material which becomes the following.

The method of forming the absorber film 4 is not particularly limited, but in the present invention, the absorber film is composed of a laminated film of a phase control layer, a low refractive index material layer and a high refractive index material layer. It is preferable to form by the ion beam sputtering method, and in this case, the materials of the phase control layer, the high refractive index layer and the low refractive index layer may be the metals or alloys listed above. In addition, by continuously forming the multilayer reflective film 2, the protective film 3 and the absorber film 4 by ion beam sputtering, a defect reduction effect can also be obtained. For example, in the case of applying the DC sputtering method to the film formation of an absorber film as in the prior art, since the substrate is once exposed to the atmosphere after the film formation of the multilayer reflective film (and the protective film), there is a possibility of dusting is there.
Although the film thickness of each of the low refractive index material layer and the high refractive index material layer constituting the absorber film 4 and the repetition period are different depending on the material applied to the absorber film, they can not be generally mentioned, but It is preferable to determine appropriately according to the method.
In addition, assuming that defect inspection using inspection light having a longer wavelength than that of EUV light having wavelengths of 193 nm, 257 nm, etc. is performed on a reflective mask blank, the effect of the present invention (film thinning effect and reflectance for EUV light In the range which does not deviate from the above, an antireflection film having a reflectance reduction effect on the inspection light may be provided on the absorber film 4.

  In addition, the reflective mask blank may have a state in which a resist film for forming a predetermined transfer pattern is formed on an absorber film.

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

[Reflective mask]
The present invention also provides a reflective mask and a method of manufacturing a reflective mask using the reflective mask blank having the above configuration.
FIG. 3 is a cross-sectional view showing the layer structure of the reflective mask, and shows a reflective mask 20 provided with 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 comprises 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 the protective film. A reflective mask comprising a transfer pattern made of an absorber film, wherein the multilayer reflective film is formed by laminating a plurality of cycles, with one cycle being 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 composed of a laminated film in which high refractive index material layers and low refractive index material layers are alternately laminated on a phase control layer, and the reflective mask blank is used. Reflected light (A) due to reflection at each interface of the low refractive index layer and the high refractive index layer forming the multilayer reflective film and the reflection on the surface of the protective film, and the absorber Said phase control layer, said high refractive index material layer, and The film thickness of the phase control layer so that the reflectance of the EUV light to the absorber film is 2% or less by the difference in the phase of the reflected light (B) due to the reflection at each interface with the refractive index material layer. Is set.

  When manufacturing a reflective mask using the above-mentioned reflective mask blank of the present invention, the method of patterning the above-mentioned absorber film 4 used as a transfer pattern in reflective mask blank 10 can perform high-definition patterning Photolithographic methods are most preferred. In the above 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 photolithographic method including etching can be applied, and damage to the multilayer reflective film can be prevented during patterning of the absorber film.

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

In a preferred embodiment of the reflective mask according to the present invention, the substrate 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 comprising a protective film and a transfer pattern comprising an absorber film on the protective film, wherein the multilayer reflective film is a laminate in which a low refractive index layer and a high refractive index layer are stacked on the substrate. The absorber film has a structure in which a plurality of cycles are stacked with one 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 and the phase control layer. And the absorber film has a thickness of 60 nm or less, and 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 Index material layer has a refractive index at a wavelength of 13.5 nm (low) is 0.95 or less, 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
The reflectance of the EUV light in the transfer pattern formation region can be recognized with respect to the reflectance of the EUV light in the reflection region where the transfer pattern is exposed. A film thickness of the phase control layer is set to have a difference in degree. With the reflective mask of this embodiment, a low reflectivity (for example, 2% or less) to EUV light can be obtained with a thinner absorber film thickness (60 nm or less) than in the prior art. Thus, it is possible to obtain a reflective mask that can be used to eliminate various problems caused by conventional shadowing and high aspect ratio.

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

Hereinafter, the embodiments of the present invention will be more specifically described by way of examples.
Example 1
Substrate used _is a glass substrate of SiO 2 -TiO ₂ system is a (6 inch square and a thickness of 6.35 mm).
Then, the end face of this glass substrate is chamfered and ground, and further, the glass substrate which has been rough-polished with a polishing solution containing cerium oxide abrasives is set on the carrier of the double-side polishing apparatus, and colloidal silica polishing is used as the polishing solution. Precision polishing was performed under predetermined polishing conditions using an alkaline aqueous solution containing particles. After completion of the precision polishing, the glass substrate was subjected to a cleaning treatment.
As described above, a glass substrate for an EUV reflective mask blank was produced. 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). The flatness was as good as 30 nm or less in the measurement area 132 mm × 132 mm.

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

  Next, the above conductive film-coated glass substrate is set in an ion beam sputtering apparatus, and the following process is performed on the main surface (surface on which the conductive film is not formed) on the side on which the transfer pattern of the glass substrate is formed. The multilayer reflective film, the protective film, and the absorber film were continuously formed.

First, in order to make a multilayer reflective film formed on a substrate a multilayer reflective film suitable for an exposure light wavelength band of 13 to 14 nm, a Mo film / Si film periodic multilayer reflective film was adopted. 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 4.2 nm, and then an Mo film was formed to 2.8 nm, and this was made one cycle, and 40 cycles were similarly laminated to form a multilayer reflective film.

Thereafter, a protective film was formed on the multilayer reflective film by ion beam sputtering as follows.
First, a Si target was used to form a 4.0 nm Si film. Subsequently, a RuNb film was deposited to a thickness of 2.5 nm using a RuNb target (Ru: Nb = 80: 20 atomic percent ratio).

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

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

The reflectance of the 13.5 nm EUV light was measured at an incident angle of 6.0 degrees with respect to this reflective mask blank, and the reflectance was 1.8%.
According to the reflective mask blank of the present embodiment, the total film thickness of the above-mentioned absorber is 39.0 nm, which is significantly larger than the total film thickness of 70 nm of the absorber 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 DRAM hp10 nm generation in a semiconductor design rule was produced as follows.
First, a resist film for electron beam drawing was formed on the above-mentioned reflective mask blank, and a predetermined pattern was drawn using an electron beam drawing machine. After drawing, predetermined development processing was performed to form a resist pattern on the reflective mask blank.
Next, using this resist pattern as a mask, the alternating cycle (5 cycles) of the Al film and the TaB film and the underlying TaB film are dry etched with a chlorine gas (Cl ₂ gas) to transfer the pattern to 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 example.

  When the final confirmation inspection of the obtained reflective mask was performed, it was confirmed that the pattern of the DRAM hp10 nm generation in the semiconductor design rule could be formed as designed.

As described above, in the reflective mask blank of the present embodiment and the reflective mask manufactured using this reflective mask blank, the EUV light reflectance to the absorber film can be suppressed to 2% or less, and in addition, the related art It was confirmed that a low reflectance (2% or less) for EUV light can be obtained with a thinner absorber film thickness, and that a thinner absorber film can be realized.
In addition, when pattern transfer by EUV light is performed on a semiconductor substrate using the obtained reflective mask of this embodiment, a semiconductor device of the DRAM hp 10 nm generation in 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 as in Example 1 on the opposite side to the side on which the transfer pattern is formed.
Next, the conductive film-coated glass substrate 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 the side on which the transfer pattern is formed. The membrane was formed continuously.

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

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

Next, similarly, an absorber film was formed on the protective film as described below by ion beam sputtering.
First, using a TaB target (Ta: B = 90: 10 atomic percent ratio), a TaB film of 4.0 nm was formed as a phase control layer. Subsequently, using a Si (amorphous) target and a TaB target (Ta: B = 90: 10 at% ratio), after forming a 2.7 nm thick Si film of a high refractive index material layer, a low refractive index material layer A TaB film of 4.4 nm was formed, and this cycle was used as one cycle, and similarly, six cycles of lamination were performed to form an absorber film composed of alternately laminated films of Si film and TaB film.
As described above, a reflective mask blank of this example was produced.
The extinction coefficient k at a wavelength of 13.5 nm of the TaB film of the phase control layer 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.

For this reflective mask blank, when the reflectance was measured at an incident angle of 6.0 degrees for EUV light of 13.5 nm, the reflectance was 1.6%.
According to the reflective mask blank of this example, the total film thickness of the above-mentioned absorber is 46.6 nm, and it is significantly compared with the total film thickness of 70 nm of the absorber 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 DRAM hp10 nm generation in a semiconductor design rule was produced as follows.
First, a resist film for electron beam drawing was formed on the above-mentioned reflective mask blank, and a predetermined pattern was drawn using an electron beam drawing machine. After drawing, predetermined development processing 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 alternate cycle (six cycles) laminated film 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. 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.

  When the final confirmation inspection of the obtained reflective mask was performed, it was confirmed that the pattern of the DRAM hp10 nm generation in the semiconductor design rule could be formed as designed.

As described above, in the reflective mask blank of the present embodiment and the reflective mask manufactured using this reflective mask blank, the EUV light reflectance to the absorber film can be suppressed to 2% or less, and in addition, the related art It was confirmed that a low reflectance (2% or less) for EUV light can be obtained with a thinner absorber film thickness, and that a thinner absorber film can be realized.
In addition, when pattern transfer by EUV light is performed on a semiconductor substrate using the obtained reflective mask of this embodiment, a semiconductor device of the DRAM hp 10 nm generation in 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 as in Example 1 on the opposite side to the side on which the transfer pattern is formed.
Next, the conductive film-coated glass substrate 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 the side on which the transfer pattern is formed. The membrane was formed continuously.

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

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

Next, similarly, an absorber film was formed on the protective film as described below by ion beam sputtering.
First, a W (tungsten) target was used, and a W film of a phase control layer was deposited to 4.2 nm. Subsequently, using a Si (amorphous) target and a W (tungsten) target, an Si film of a high refractive index material layer is formed to a thickness of 2.5 nm, and then a W film of a low refractive index material layer is formed to a thickness of 4.7 nm Taking this as one cycle, four cycles were similarly laminated to form an absorber film composed of an alternately laminated film of Si film and W film.
As described above, a reflective mask blank of this example was produced.
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.

For this reflective mask blank, when the reflectance was measured at an incident angle of 6.0 degrees for EUV light of 13.5 nm, the reflectance was 1.6%.
According to the reflective mask blank of this example, the total film thickness of the above-mentioned absorber is 33.0 nm, and it is significantly compared with the total film thickness of 70 nm of the absorber 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 DRAM hp10 nm generation in a semiconductor design rule was produced as follows.
First, a resist film for electron beam drawing was formed on the above-mentioned reflective mask blank, and a predetermined pattern was drawn using an electron beam drawing machine. After drawing, predetermined development processing 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 alternate cycle (four cycles) laminated film of the Si film and the W film and the W film in the lower layer by a mixed gas of chlorine gas (SF ₆ ) and oxygen. A transfer pattern was formed on the body membrane.
Further, the resist pattern remaining on the absorber film pattern was removed with hot sulfuric acid to obtain a reflective mask of this example.

  When the final confirmation inspection of the obtained reflective mask was performed, it was confirmed that the pattern of the DRAM hp10 nm generation in the semiconductor design rule could be formed as designed.

As described above, in the reflective mask blank of the present embodiment and the reflective mask manufactured using this reflective mask blank, the EUV light reflectance to the absorber film can be suppressed to 2% or less, and in addition, the related art It was confirmed that a low reflectance (2% or less) for EUV light can be obtained with a thinner absorber film thickness, and that a thinner absorber film can be realized.
In addition, when pattern transfer by EUV light is performed on a semiconductor substrate using the obtained reflective mask of this embodiment, a semiconductor device of the DRAM hp 10 nm generation in 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 as in Example 1 on the opposite side to the side on which the transfer pattern is 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 the transfer pattern is formed.

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

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

Next, as an absorber film, a TaBSiN film (film thickness 60 nm, Ta: B: Si: N = 70: 3: 10: 17 atomic%) is formed on the protective film of the multilayer reflective film coated substrate manufactured as described above. A laminated film of a ratio) and a TaBSiON film (film thickness 10 nm, Ta: B: Si: O: N = 40: 3: 10: 37: 10 at% ratio) was formed by DC magnetron sputtering. The total film thickness of the absorber is 70 nm.
As described above, a reflective mask blank of this comparative example was produced.
For this reflective mask blank, when the reflectance was measured at an incident angle of 6.0 degrees for EUV light of 13.5 nm, the reflectance was 0.4%.

Next, using this reflective mask blank, a reflective mask for EUV exposure having a pattern of DRAM hp10 nm generation in a semiconductor design rule was produced as follows.
First, a resist film for electron beam drawing was formed on the above-mentioned reflective mask blank, and a predetermined pattern was drawn using an electron beam drawing machine. After drawing, predetermined development processing was performed to form a resist pattern on the reflective mask blank.
Next, using this resist pattern as a mask, dry-etch the upper TaBSiON film with a fluorine-based gas (CF ₄ gas) and the lower TaBSiN film with a chlorine-based gas (Cl ₂ gas), and transfer the transfer pattern to the absorber film. It formed.
Furthermore, the resist pattern remaining on the absorber film pattern was removed with hot sulfuric acid to obtain a reflective mask of this comparative example.

When the final confirmation inspection of the obtained reflective mask was performed, it was confirmed that the pattern of the DRAM hp10 nm generation in the semiconductor design rule could be formed as designed.
However, when pattern transfer by EUV light is performed on a semiconductor substrate using the obtained reflective mask of the present comparative example, since the film thickness of the absorber film is as thick as 70 nm, the pattern by shadowing or high aspect ratio It can cause defects.

Reference Signs List 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 (12)

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,
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 stacked is stacked on a plurality of cycles, with one cycle being formed on the substrate,
The absorber film is composed of a phase control layer, and a laminated film formed by alternately laminating a high refractive index material layer and a low refractive index material layer on the phase control layer,
Reflected light (A) due to reflection at each interface of the low refractive index layer and the high refractive index layer constituting the multilayer reflective film upon incidence on the reflective mask blank and reflection on the surface of the protective film The absorber is different in the phase of the reflected light (B) by reflection at each interface with the phase control layer, the high refractive index material layer, and the low refractive index material layer constituting the absorber film. The film thickness of the said phase control layer is set so that the reflectance of EUV light with respect to a film | membrane may be 2% or less, The reflective mask blank characterized by the above-mentioned.   The film thickness is set such that the phase control layer is incident on the reflective mask blank and the phase of the reflected light (A) and the reflected light (B) differ by 180 ° ± 10 °. The reflective mask blank according to claim 1, characterized in that   3. The reflective mask blank according to claim 1, 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. 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 and an extinction coefficient k (low) of 0.03 or more, and the absorber 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
The reflective mask blank according to any one of claims 1 to 3, which satisfies the condition indicated by 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,
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 stacked is stacked on a plurality of cycles, with one cycle being formed on the substrate,
The absorber film is composed of a phase control layer, and a laminated film formed by alternately laminating a high refractive index material layer and a low refractive index material layer on the phase control layer, and the absorber film The film thickness is 60 nm or less,
The phase control layer is a material whose extinction coefficient k at a wavelength of 13.5 nm is 0.03 or more, and the low refractive index 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, 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 indicated by
A reflective mask blank characterized in that the film thickness of the phase shift control layer is set such that the reflectance of EUV light to the absorber film is equal to or less than a predetermined reflectance.   The reflective mask blank according to claim 5, wherein the phase control layer has a film thickness set such that a reflectance of EUV light with respect to the absorber film is 2% or less.   A method of manufacturing a reflective mask, comprising patterning the absorber film in the reflective mask blank according to any one of claims 1 to 6. 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, a transfer pattern comprising an absorber film on the protective film A reflective mask comprising
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 stacked is stacked on a plurality of cycles, with one cycle being formed on the substrate,
The absorber film is composed of a phase control layer, and a laminated film formed by alternately laminating a high refractive index material layer and a low refractive index material layer on the phase control layer,
Reflected light (A) due to reflection at each interface of the low refractive index layer and the high refractive index layer constituting the multilayer reflective film upon incidence on the reflective mask, and reflection on the surface of the protective film, The phase difference of the reflected light (B) by reflection at each interface between the phase control layer constituting the absorber film, the high refractive index material layer, and the low refractive index material layer makes the absorber film different. The film thickness of the said phase control layer is set so that the reflectance of EUV light with respect to may be 2% or less.   The film thickness of the phase control layer is set such that the phase of the reflected light (A) and the reflected light (B) is different by 180 ° ± 10 ° upon entering the reflective mask. The reflective mask according to claim 8, characterized in that: 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, a transfer pattern comprising an absorber film on the protective film A reflective mask comprising
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 stacked is stacked on a plurality of cycles, with one cycle being formed on the substrate,
The absorber film is composed of a phase control layer, and a laminated film formed by alternately laminating a high refractive index material layer and a low refractive index material layer on the phase control layer, and the absorber film The film thickness is 60 nm or less,
The phase control layer is a material whose extinction coefficient k at a wavelength of 13.5 nm is 0.03 or more, and the low refractive index 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, 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 indicated by
The phase control so that the reflectance of EUV light in the transfer pattern formation region is different to the reflectance of EUV light in the reflection region where the transfer pattern is exposed, so that the transfer pattern can be recognized. A reflective mask characterized in that the film thickness of the layer is set.   11. The reflective mask according to claim 10, wherein the film thickness of the phase control layer is set such that the reflectance of EUV light to the absorber film is 2% or less. A semiconductor comprising the step of forming a pattern on a semiconductor substrate using a reflective mask obtained by the manufacturing method according to claim 7 or the reflective mask according to any one of claims 8 to 11. Device manufacturing method.

Images