WO2017169658A1 - 反射型マスクブランク、反射型マスク及び半導体装置の製造方法 - Google Patents
反射型マスクブランク、反射型マスク及び半導体装置の製造方法 Download PDFInfo
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- WO2017169658A1 WO2017169658A1 PCT/JP2017/009721 JP2017009721W WO2017169658A1 WO 2017169658 A1 WO2017169658 A1 WO 2017169658A1 JP 2017009721 W JP2017009721 W JP 2017009721W WO 2017169658 A1 WO2017169658 A1 WO 2017169658A1
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- film
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- phase shift
- reflective mask
- mask blank
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Images
Classifications
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F1/00—Originals for photomechanical production of textured or patterned surfaces, e.g., masks, photo-masks, reticles; Mask blanks or pellicles therefor; Containers specially adapted therefor; Preparation thereof
- G03F1/22—Masks or mask blanks for imaging by radiation of 100nm or shorter wavelength, e.g. X-ray masks, extreme ultraviolet [EUV] masks; Preparation thereof
- G03F1/24—Reflection masks; Preparation thereof
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F1/00—Originals for photomechanical production of textured or patterned surfaces, e.g., masks, photo-masks, reticles; Mask blanks or pellicles therefor; Containers specially adapted therefor; Preparation thereof
- G03F1/26—Phase shift masks [PSM]; PSM blanks; Preparation thereof
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F1/00—Originals for photomechanical production of textured or patterned surfaces, e.g., masks, photo-masks, reticles; Mask blanks or pellicles therefor; Containers specially adapted therefor; Preparation thereof
- G03F1/26—Phase shift masks [PSM]; PSM blanks; Preparation thereof
- G03F1/32—Attenuating PSM [att-PSM], e.g. halftone PSM or PSM having semi-transparent phase shift portion; Preparation thereof
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
- G03F7/20—Exposure; Apparatus therefor
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/027—Making masks on semiconductor bodies for further photolithographic processing not provided for in group H01L21/18 or H01L21/34
Definitions
- the present invention relates to a reflective mask blank and a reflective mask, which are original plates for manufacturing an exposure mask used for manufacturing a semiconductor device, and a method for manufacturing a semiconductor device using the reflective mask.
- EUV lithography using extreme ultraviolet (EUV) near 13.5 nm as a wavelength of a light source has been proposed.
- EUV lithography a reflective mask is used because the difference in absorption rate between materials for EUV light is small.
- a multilayer reflective film that reflects exposure light is formed on a substrate, and a phase shift film that absorbs exposure light is formed in a pattern on a protective film for protecting the multilayer reflective film.
- the light incident on the reflective mask mounted on the exposure machine is absorbed by the part with the phase shift film pattern and reflected by the multilayer reflective film at the part without the phase shift film pattern.
- the image is transferred onto the semiconductor substrate through the reflective optical system.
- Part of the exposure light incident on the phase shift film pattern is reflected with a phase difference of about 180 degrees from the light reflected by the multilayer reflective film (phase shift), thereby obtaining contrast (resolution).
- Patent Documents 1 to 3 disclose techniques relating to such a reflective mask for EUV lithography and a mask blank for producing the same.
- Patent Document 1 describes that a thin film (phase shift film) is a two-layer film in order to improve the transfer resolution by applying the principle of a halftone mask to EUV exposure.
- a specific material of the two-layer film a combination of a Mo layer and a Ta layer is described.
- Patent Document 2 in order to improve the transfer resolution by applying the principle of a halftone mask to EUV exposure, a material of a halftone film (phase shift film) made of a single layer film, a refractive index and an extinction
- FIG. 2 of patent document 2 shown by the plane coordinate which uses a coefficient as a coordinate axis, selecting from the area
- TaMo composition ratio 1: 1
- Patent Document 3 in a halftone EUV mask, in order to reduce the projection effect (shadowing effect) and to have a high degree of freedom in reflectivity selectivity and a high cleaning resistance, the material of the halftone film is Ta. And a compound of Ru and that the composition range is defined.
- the shadowing effect is the following phenomenon.
- an exposure apparatus that uses a reflective mask
- light is incident on the mask with a slight inclination from the vertical direction so that the optical axes of incident light and reflected light do not overlap.
- the phase shift film pattern of the mask is thick, a shadow based on the thickness of the phase shift film pattern is generated due to the inclination in the light incident direction.
- the change in the size of the transfer pattern by the amount of the shadow is called a shadowing effect.
- Patent Document 4 includes a high reflection portion formed on a substrate and a patterned low reflection portion formed on the high reflection portion, where the low reflection portion is Ta (tantalum) or Mo (molybdenum). And a halftone EUV mask with Si (silicon) is described.
- the phase shift film of the reflective mask includes light that is reflected by a part of the multilayer reflective film of the exposure light incident on the phase shift film pattern, and light that is reflected by the multilayer reflective film in a part without the phase shift film pattern. Is designed to have a phase difference of about 180 degrees with respect to light having a wavelength of 13.5 nm. Further, an antireflection layer using a material having a low reflectance in the inspection light exposure is provided on the surface of the phase shift film. In the case of a phase shift film composed of two or more layers, the interference between the reflected light from the outermost surface of the phase shift film and the reflected light from the multilayer reflective film existing under the phase shift film, for example, is shown in FIG.
- an object of the present invention is to provide a reflective mask blank having a phase shift film in which the film thickness dependence of retardation is small.
- the inventors of the present invention transmitted the reflected light from the uppermost layer of the phase shift film and the phase shift film by providing the phase shift film with a reflection suppressing function. It has been found that it is possible to suppress the occurrence of a vibration structure in the film thickness dependence of the phase difference by weakening the interference of light with the reflected light from the multilayer reflective film.
- the present inventors have found that a reflective mask blank having a phase shift film having a small film thickness dependency of retardation is obtained by suppressing the occurrence of a vibration structure in the film thickness dependency of retardation. Invented.
- the reflection suppression function of the phase shift film works effectively when it is in the range of ⁇ ⁇ (nm), centering on odd multiples, and it is possible to suppress the occurrence of a vibration structure in the film thickness dependence of the phase difference. I found it.
- the present invention has the following configuration.
- the present invention is a reflective mask blank having the following configurations 1 to 9, a reflective mask having the following configuration 10, and a method for manufacturing a semiconductor device having the following configuration 11.
- Configuration 1 of the present invention is a reflective mask blank in which a multilayer reflective film and a phase shift film for shifting the phase of EUV light are formed in this order on a substrate,
- the phase shift film has an uppermost layer and a lower layer other than the uppermost layer, n 2 ⁇ n 1 ⁇ 1 (1) and ⁇ / 4 ⁇ (2m + 1) ⁇ ⁇ n 1 ⁇ d 1 ⁇ ⁇ / 4 ⁇ (2m + 1) + ⁇ (2)
- d 1 is the film thickness of the uppermost layer.
- Nm is an integer greater than or equal to zero
- ⁇ 1.5 nm.
- Configuration 2 of the present invention is the reflective mask blank according to Configuration 1, wherein m is 2 or less.
- the phase shift film can be thinned by setting m to 2 or less. Therefore, the shadowing effect of the obtained reflective mask can be suppressed.
- Configuration 3 of the present invention is the reflective mask blank according to Configuration 1 or 2, wherein the uppermost layer of the phase shift film is made of a material containing a silicon compound, and the lower layer is made of a material containing a tantalum compound. .
- the phase shift film includes the uppermost layer and the lower layer of the predetermined material, so that a desired phase shift amount can be obtained.
- Configuration 4 of the present invention is a reflective mask blank in which a multilayer reflective film and a phase shift film for shifting the phase of EUV light are formed in this order on a substrate,
- the phase shift film is composed of a single unit thin film including the first to Nth layers (N is an integer of 2 or more) in this order, or a multilayer film including two or more layers, and is the farthest from the multilayer reflective film.
- the first layer of the unit thin film located is the top layer, It is a reflective mask blank characterized by satisfying the above relationship.
- i is an integer from 1 ⁇ N
- d i is the thickness of said i-layer (nm)
- alpha 1 .5 nm.
- Configuration 5 of the present invention is the reflective mask blank according to Configuration 4, wherein n i + 1 ⁇ n i and n 1 ⁇ 1.
- the refractive index of the (i + 1) th layer is smaller than the refractive index of the i-th layer, and the refractive index of the first layer is less than 1. Thereby, reflection on the surface of the phase shift film can be further reduced.
- Structure 7 of the present invention is the reflective mask blank according to any one of Structures 4 to 6, wherein the first layer contains at least one metal material selected from Ta and Cr.
- the first layer includes at least one metal material selected from Ta and Cr, thereby obtaining an appropriate refractive index and extinction coefficient as the first layer of the phase shift film. Can do.
- Configuration 8 of the present invention is the reflection type according to any one of Configurations 4 to 7, wherein the second layer includes at least one metal material selected from Mo, Ru, Pt, Pd, Ag, and Au. It is a mask blank.
- a ninth aspect of the present invention is the reflective mask blank according to any one of the first to eighth aspects, wherein a protective film is provided between the multilayer reflective film and the phase shift film.
- the protective film is formed on the multilayer reflective film, thereby suppressing damage to the multilayer reflective film surface when the reflective mask is manufactured using the substrate with the multilayer reflective film. be able to. Accordingly, the reflectance characteristics of the reflective mask with respect to EUV light are improved.
- a reflective mask characterized by having a phase shift film pattern obtained by patterning the phase shift film in the reflective mask blank of any one of the first to ninth aspects.
- the above-described reflective mask blank is used for manufacturing the reflective mask having the constitution 10 of the present invention, it is possible to obtain a reflective mask having a phase shift film pattern in which the film thickness dependence of the phase difference is small.
- a semiconductor device manufacturing method including a pattern forming step of forming a pattern on a semiconductor substrate using the reflective mask according to the tenth aspect.
- the semiconductor device manufacturing method of the eleventh aspect of the present invention it is possible to use a reflective mask having a phase shift film pattern in which the film thickness dependence of the phase difference is small, and thus a fine and highly accurate transfer pattern is provided.
- a semiconductor device can be manufactured.
- a reflective mask having a phase shift film pattern in which the phase difference of the phase difference is small can be obtained.
- the semiconductor device manufacturing method of the present invention can use a reflective mask having a phase shift film pattern in which the film thickness dependence of retardation is small, so that a semiconductor device having a fine and highly accurate transfer pattern can be obtained. Can be manufactured.
- FIG. 4 is an enlarged view of Example 1 and Comparative Example 1 shown in FIG. 3, showing a film thickness range in which the phase difference variation is 10 degrees (phase difference of 175 to 185 degrees). It is a graph which shows the characteristic of the extinction coefficient k and refractive index n of a metal material in EUV light (wavelength 13.5nm).
- FIG. 10 is a diagram showing the relationship between the thickness of the phase shift film of Examples 5 to 7 and the phase difference obtained by simulation.
- FIG. 1 the cross-sectional schematic diagram of the reflective mask blank 10 which is Embodiment 1 of this invention is shown.
- a multilayer reflective film 13 and a phase shift film 15 for shifting the phase of EUV light are formed on a substrate 12 in this order.
- the phase shift film 15 of the reflective mask blank 10 of this embodiment has an uppermost layer 16 and a lower layer 17 other than the uppermost layer 16.
- the phase shift film 15 of the reflective mask blank 10 of the present embodiment has a relationship of the following formulas (1) and (2): n 2 ⁇ n 1 ⁇ 1 (1) and ⁇ / 4 ⁇ (2m + 1) ⁇ ⁇ n 1 ⁇ d 1 ⁇ ⁇ / 4 ⁇ (2m + 1) + ⁇ (2) Meet.
- d 1 is the film thickness of the uppermost layer 16
- m is an integer greater than or equal to zero
- ⁇ 1.5.
- the reflective mask blank 10 shown in FIG. 1 has a single lower layer 17.
- FIG. 2 the cross-sectional schematic diagram of the reflective mask blank 10 which is Embodiment 2 of this invention is shown.
- a multilayer reflective film 13 and a phase shift film 15 for shifting the phase of EUV light are formed on a substrate 12 in this order.
- the unit thin film 18 includes one layer or two or more layers. In this specification, the number of repetitions of the unit thin film 18 is referred to as “period”.
- the first layer 15 a of the unit thin film 18 located farthest from the multilayer reflective film 13 among the unit thin films 18 of the phase shift film 15 is the uppermost layer 16.
- the unit thin films 18 are laminated so that the first layer 15 a of each unit thin film 18 is located farther from the multilayer reflective film 13.
- the phase shift film 15 of the reflective mask blank 10 of the present embodiment has the relationship of the following formula (3): Meet.
- i is an integer from 1 to N
- FIG. 3 shows the relationship between the film thickness of the phase shift film 15 and the phase difference.
- the thickness of the phase shift film 15 and the phase difference are not in a monotonically increasing relationship. This is due to the interference between the reflected light from the uppermost layer 16 of the phase shift film 15 and the reflected light from the multilayer reflective film 13 of the light transmitted through the phase shift film 15 (vibrational change ( This is because in this specification, this is referred to as “vibration structure”).
- the predetermined film constituting the phase shift film 15 satisfies the above-described relationship between the predetermined refractive index and film thickness, so that the reflection suppressing function is applied to the uppermost layer 16 of the phase shift film 15. Can be given.
- the uppermost layer 16 of the phase shift film 15 With a reflection suppressing function, interference between the reflected light from the uppermost layer 16 and the reflected light from the multilayer reflective film 13 can be weakened. As a result, it is possible to suppress the occurrence of a vibration structure in the film thickness dependence of the phase difference.
- FIG. 3 when the example of the present invention is compared with the comparative example, it can be seen that the vibration structure of the example of the present invention is smaller than the comparative example.
- the small vibration structure means that the film thickness dependence of the retardation is small.
- the refractive index and film thickness of a predetermined film constituting the phase shift film 15 satisfy a predetermined relationship as expressed by the above formulas (1) to (3).
- the reflective mask blank 10 having the phase shift film 15 in which the film thickness dependency of the retardation is small it is possible to obtain the reflective mask blank 10 having the phase shift film 15 in which the film thickness dependency of the retardation is small.
- Reflective mask blank 10 according to the second embodiment of the present invention, n i +1 ⁇ n i, and is preferably n 1 ⁇ 1. This is because reflection on the surface of the phase shift film 15 can be further reduced.
- N 2
- FIG. 1 is a schematic cross-sectional view for explaining the configuration of a reflective mask blank 10 for EUV lithography according to Embodiment 1 of the present invention.
- FIG. 2 is a schematic cross-sectional view for explaining the configuration of a reflective mask blank 10 for EUV lithography according to Embodiment 2 of the present invention.
- the reflective mask blank 10 of the present invention will be described with reference to FIGS.
- the reflective mask blank 10 includes a substrate 12, a multilayer reflective film 13, a protective film 14, and a phase shift film 15.
- the substrate 12 has a back surface conductive film 11 for electrostatic chuck formed on the main surface on the back surface side of the substrate 12.
- the multilayer reflective film 13 is formed on the main surface of the substrate 12 (the main surface opposite to the side on which the back conductive film 11 is formed).
- the multilayer reflective film 13 reflects EUV light that is exposure light.
- the protective film 14 is formed on the multilayer reflective film 13 with a material mainly containing ruthenium (Ru) for protecting the multilayer reflective film 13.
- the phase shift film 15 is formed on the protective film 14.
- the phase shift film 15 absorbs EUV light and reflects part of the EUV light to shift the phase.
- a multilayer reflective film 13 formed on the main surface of the substrate 12 means that the multilayer reflective film 13 is disposed in contact with the surface of the substrate 12.
- a case where it means that another film is provided between the substrate 12 and the multilayer film 26 for mask blank is included.
- the film A is disposed on the film B means that the film A and the film B are not interposed between the film A and the film B without interposing another film. It means that it is arranged so that it touches directly.
- a substrate 12 having a low thermal expansion coefficient within a range of 0 ⁇ 5 ppb / ° C. is preferably used.
- a material having a low thermal expansion coefficient in this range for example, SiO 2 —TiO 2 glass, multicomponent glass ceramics, or the like can be used.
- the main surface on the side where the phase shift film 15 serving as the transfer pattern of the reflective mask is formed has a surface with high flatness from the viewpoint of at least pattern transfer accuracy and position accuracy.
- the flatness is preferably 0.1 ⁇ m or less, more preferably 0.05 ⁇ m or less, particularly preferably in a 132 mm ⁇ 132 mm region of the main surface on the side where the transfer pattern of the substrate 12 is formed. 0.03 ⁇ m or less.
- the main surface opposite to the side on which the phase shift film 15 is formed is formed with a back surface conductive film 11 for electrostatic chucking when set in the exposure apparatus.
- the flatness of the surface on which the back conductive film 11 is formed is preferably 1 ⁇ m or less, more preferably 0.5 ⁇ m or less, and particularly preferably 0.3 ⁇ m or less in a 142 mm ⁇ 142 mm region.
- the flatness is a value representing the warpage (deformation amount) of the surface indicated by TIR (Total Indicated Reading). This value is determined by taking the plane defined by the least square method with respect to the surface of the substrate 12 as a focal plane, and the highest position of the surface of the substrate 12 above the focal plane and the surface of the substrate 12 below the focal plane. This is the absolute value of the difference in height from the lowest position.
- the surface smoothness required for the substrate 12 is that the surface roughness of the main surface of the substrate 12 on the side where the phase shift film 15 serving as a transfer pattern is formed is the root mean square roughness ( RMS) is preferably 0.1 nm or less.
- the surface smoothness can be measured with an atomic force microscope (AFM).
- the substrate 12 has high rigidity in order to prevent a film (such as the multilayer reflective film 13) formed thereon from being deformed by film stress.
- the substrate 12 preferably has a high Young's modulus of 65 GPa or more.
- the multilayer reflective film 13 has a function of reflecting EUV light in a reflective mask for EUV lithography.
- the multilayer reflective film 13 is a multilayer film in which elements having different refractive indexes are periodically stacked.
- a thin film (high refractive index layer) of a light element or a compound thereof, which is a high refractive index material, and a thin film (low refractive index layer) of a heavy element or a compound thereof, which is a low refractive index material, are alternately 40
- a multilayer film having about 60 cycles is used as the multilayer reflective film 13.
- the multilayer film can have a structure in which a plurality of high-refractive index layers / low-refractive index layers are stacked in this order from the substrate 12 side and a plurality of periods are stacked.
- the multilayer film can have a structure in which a low refractive index layer and a high refractive index layer laminated in this order from the substrate 12 side are laminated in a plurality of periods with a laminated structure of a low refractive index layer / high refractive index layer as one period.
- the uppermost layer has a low refractive index. Become a rate layer. For this reason, it is preferable to form a multilayer reflective film 13 by further forming a high refractive index layer on the uppermost low refractive index layer.
- a layer containing Si can be adopted as the high refractive index layer.
- a material containing Si in addition to Si alone, a Si compound containing B, C, N, and / or O in Si can be used.
- a layer containing Si as the high refractive index layer, a reflective mask for EUV lithography having excellent EUV light reflectivity can be obtained.
- a glass substrate is preferably used as the substrate 12.
- Si has excellent adhesion to a glass substrate.
- the low refractive index layer a single metal selected from Mo, Ru, Rh, and Pt, and alloys thereof are used.
- the multilayer reflective film 13 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 example, about 40 to 60 cycles is preferably used.
- a high refractive index layer, which is the uppermost layer of the multilayer reflective film 13, is formed of silicon (Si), and a silicon oxide layer containing silicon and oxygen is interposed between the uppermost layer (Si) and the protective film 14. Can be formed. Thereby, the mask cleaning resistance (resistance to peeling of the phase shift film pattern) can be improved.
- the reflectance of the multilayer reflective film 13 alone is, for example, 65% or more, and the upper limit is preferably 73%.
- the film thickness and the number of periods of each constituent layer of the multilayer reflective film 13 are appropriately selected so as to satisfy Bragg's law depending on the exposure wavelength.
- the multilayer reflective film 13 there are a plurality of high refractive index layers and low refractive index layers. All the high refractive index layers do not have to have the same film thickness. Further, all the low refractive index layers may not have the same film thickness.
- the film thickness of the outermost Si layer of the multilayer reflective film 13 can be adjusted within a range in which the reflectance is not lowered.
- the film thickness of the outermost Si (high refractive index layer) can be set to 3 to 10 nm, for example.
- each layer of the multilayer reflective film 13 can be formed by ion beam sputtering.
- an Si film having a film thickness of about 4 nm is first formed on the substrate 12 using an Si target, for example, by an ion beam sputtering method, and then a film thickness of about 3 nm is formed using the Mo target.
- the Mo film is formed.
- the Si film and the Mo film are formed as one cycle, and the multilayer reflective film 13 is formed by laminating a total of 40 to 60 cycles (the uppermost layer is a Si layer).
- the reflective mask blank 10 of the present invention preferably has a protective film 14 between the multilayer reflective film 13 and the phase shift film 15.
- the protective film 14 is formed on the multilayer reflective film 13 in order to protect the multilayer reflective film 13 from dry etching or cleaning liquid in a manufacturing process of a reflective mask for EUV lithography described later. Is done.
- the protective film 14 is made of, for example, a material (main component: 50 atomic% or more) containing Ru (ruthenium) as a main component.
- the material containing Ru as a main component is Ru metal alone, Ru alloy containing a metal such as Nb, Zr, Y, B, Ti, La, Mo, Co, and / or Re in Ru, or N in these materials. It may be a material containing (nitrogen).
- the protective film 14 can have a laminated structure of three or more layers. In this case, the protective film 14 has a structure in which the lowermost layer and the uppermost layer are layers made of a substance containing Ru, and a metal or alloy other than Ru is interposed between the lowermost layer and the uppermost layer. be able to.
- the thickness of the protective film 14 is not particularly limited as long as it can function as the protective film 14. From the viewpoint of EUV light reflectance, the thickness of the protective film 14 is preferably 1.5 to 8.0 nm, and more preferably 1.8 to 6.0 nm.
- a known film forming method can be employed without any particular limitation.
- Specific examples of the method for forming the protective film 14 include a sputtering method and an ion beam sputtering method.
- the reflective mask blank 10 of Embodiment 1 of the present invention includes a phase shift film 15 on a multilayer reflective film 13.
- the phase shift film 15 can be formed on and in contact with the multilayer reflective film 13. Further, when the protective film 14 is formed, the protective film 14 can be formed in contact with the protective film 14.
- the phase shift film 15 of the reflective mask blank 10 includes a multilayer including a first layer 15a (uppermost layer 16) and a second layer 15b (lower layer 17). It is a membrane.
- the phase shift film 15 of the reflective mask blank 10 has a structure in which a plurality of one first layer 15a and one second layer 15b are alternately stacked. Can have.
- the pair of first layer 15a and second layer 15b is referred to as “unit thin film 18”.
- the unit thin film 18 can be a multilayer film of the first layer 15a to the Nth layer (N is an integer of 2 or more).
- the set of first layer 15a to Nth multilayer films is the “unit thin film 18”.
- N which is the number of layers of the multilayer film constituting the unit thin film 18, is preferably 2.
- the uppermost layer 16 (first layer 15a) of the phase shift film 15 is made of a material containing a silicon compound
- the lower layer 17 (second layer 15b) is made of a material containing a tantalum compound.
- the uppermost layer 16 is a layer located farthest from the multilayer reflective film 13 among the layers constituting the phase shift film 15.
- the first layer 15a of the reflective mask blank 10 of the present invention can include at least one metal material selected from Ta and Cr.
- the uppermost layer 16 made of at least one metal material selected from Ta and Cr.
- FIG. 5 shows the relationship between the refractive index n of a metal material at a wavelength of 13.5 nm and the extinction coefficient k.
- Ta has a small extinction coefficient of EUV light, and can be easily dry-etched with a fluorine-based gas or a chlorine-based gas. Therefore, Ta is a material for the phase shift film 15 having excellent workability. Further, by adding B, Si and / or Ge or the like to Ta, an amorphous material can be easily obtained, and the smoothness of the phase shift film 15 can be improved. Further, when N and / or O is added to Ta, the resistance of the phase shift film 15 to oxidation is improved. Therefore, by using a material obtained by adding N and / or O to Ta for the uppermost layer 16 of the phase shift film 15, it is possible to obtain an effect that the cleaning resistance is excellent and the stability over time can be improved.
- a kind of metal material is preferably selected, but is not limited thereto.
- two or more kinds of metal materials may be selected.
- the second layer 15b preferably contains at least one metal material selected from Mo, Ru, Pt, Pd, Ag, and Au.
- the lower layer 17 made of this metal material is more preferably used in combination with the first layer 15a containing at least one metal material selected from Ta and Cr.
- the metal material forming the second layer 15b is a metal material different from the first layer 15a, and the refractive index n at a wavelength of 13.5 nm is the refractive index of the material forming the first layer 15a. It is preferable to select from metal materials smaller than n.
- Mo has a concern about washing resistance by itself
- the washing resistance can be improved by forming a multilayer film in combination with the layer containing Ta or Cr described above.
- Mo has a refractive index n of less than 0.95 in EUV light, it is possible to obtain a phase shift effect with a thin film thickness.
- Mo has a small extinction coefficient k, the reflectance of EUV light is high, and it is a film material that easily obtains contrast (resolution) due to the phase shift effect.
- Ru alone has a low etching rate with respect to various etching gases and has a high processing difficulty.
- the entire phase shift film 15 is formed. The workability of the can be improved.
- Ru has a refractive index n of less than 0.95 in EUV light, it is possible to obtain a phase shift effect with a thin film thickness.
- Ru is a film material that has a low extinction coefficient k and thus has high EUV light reflectivity, and can easily obtain contrast (resolution) due to the phase shift effect.
- Pt and Pd are film materials having a low etching rate and difficulty in processing. However, since the refractive index n in EUV light is smaller than 0.95, Pt and Pd can obtain a phase shift effect with a thin film thickness.
- a kind of metal material is preferably selected, but is not limited thereto. Two or more metal materials may be selected as the material for forming the second layer 15b.
- the metal material that can be used as a material for forming the first layer 15a and the second layer 15b is preferably a single metal. However, a material containing the metal can be used on condition that the phase shift effect of the phase shift film 15 is not affected.
- Ta used as a material for forming the first layer 15a
- a TaB alloy containing Ta as a main component and containing B a TaSi alloy containing Ta as a main component and containing Si
- Ta are mainly used.
- Ta alloys containing other transition metals (for example, Pt, Pd, and Ag) as components, Ta metals, and Ta compounds obtained by adding N, O, H, C, or the like to these alloys can be used.
- the material containing Cr include a CrSi alloy containing Cr as a main component and containing Si, a Cr alloy containing Cr as a main component and other transition metals (for example, Pt, Pd, Ag), a Cr metal, and alloys thereof.
- Cr-based compounds in which N, O, H, and / or C, etc. are added to can be used.
- a Mo alloy containing Mo as a main component and containing a metal such as Nb, Zr, Y, B, Ti, La, Ru, Co and / or Re. Etc. can be used as a material containing Mo for forming the second layer 15b.
- a Ru alloy containing Ru as a main component and containing a metal such as Nb, Zr, Y, B, Ti, La, Mo, Co and / or Re is used. be able to.
- a material containing Ru, a Ru alloy or a Ru metal, and a Ru-based compound in which N, H, and / or C or the like is added to these alloys can be used as a material containing Ru, a Ru alloy or a Ru metal, and a Ru-based compound in which N, H, and / or C or the like is added to these alloys can be used as a material containing Ru, a Ru alloy or a Ru metal, and a Ru-based compound in which N, H, and / or C or the
- a Pd alloy containing Pd as a main component and containing a metal such as Nb, Zr, Y, B, Ti, La, Mo, Co and / or Re is used. be able to.
- an Ag alloy containing a metal such as Nb, Zr, Y, B, Ti, La, Mo, Co, and / or Re with Ag as a main component can be used.
- an Au alloy containing a metal such as Nb, Zr, Y, B, Ti, La, Mo, Co, and / or Re with Au as a main component is used. Can be used.
- the lowermost layer of the phase shift film 15 and the layer thereon are the second layer 15b containing another metal material that does not overlap with the material for forming the protective film 14 formed thereunder (Ru protective film ⁇ Other than Ru ...
- the protective film 14 is formed of a material mainly containing Ru (Ru protective film ⁇ Ru 7), both are common. This combination should be avoided because it forms and overlaps with Ru.
- the lowermost layer of the phase shift film 15 is, for example, a second layer 15b containing Mo having high etching selectivity with respect to Ru of the protective film 14 (Ru protective film ⁇ Mo ⁇ %) High-definition patterning can be performed, and damage to the protective film 14 can be suppressed.
- the uppermost layer 16 of the phase shift film 15 is the uppermost layer 16 (first layer 15a) containing a metal material determined according to the etching selectivity.
- first layer 15a containing Ta or Cr and the second layer 15b containing Mo are unit thin films of the phase shift film 15
- the uppermost layer 16 is the first layer 15a containing Ta or Cr.
- the lowermost layer of the phase shift film 15 can be the second layer 15b containing Mo
- the uppermost layer 16 of the phase shift film 15 can be the first layer 15a containing Ta (Ru protective film ⁇ Mo ⁇ Ta... Mo ⁇ Ta). Since Mo has high etching selectivity with respect to Ru of the protective film 14, high-definition patterning can be performed, damage to the protective film 14 can be suppressed, and cleaning resistance before and after pattern formation can be suppressed. Can be improved.
- the lowermost layer of the phase shift film 15 may be the first layer 15a containing Ta (Ru protective film 14 ⁇ Ta ⁇ Mo ⁇ Ta ⁇ Mo ... ⁇ Ta).
- the first layer 15 a further containing Ta is formed on the protective film 14.
- the unit thin film 18 constituting the phase shift film 15 is formed of two or more thin films.
- the Nth layer (N is an integer of 2 or more) of the unit thin film 18 in the phase shift film 15 is formed of the same metal material.
- the phase shift film 15 can be composed of a first layer 15a containing Ta, a second layer 15b containing Mo, and a third layer (not shown) containing Ru (Ru protective film 14 ⁇ Ta ⁇ Ru ⁇ Mo ⁇ Ta ... Ru ⁇ Mo ⁇ Ta).
- a thin film containing Ta is further formed on and in contact with the Ru protective film 14. In this case, since the content ratio of the Ta layer in the phase shift film 15 can be reduced, the phase shift effect can be easily obtained.
- the phase shift film 15 can be formed by a known film formation method such as an ion beam sputtering method.
- a known film formation method such as an ion beam sputtering method.
- the ion beam sputtering method two targets formed of each metal material of the first layer 15a and the second layer 15b are prepared, and in an atmosphere of an inert gas such as Ar gas, The first layer 15a and the second layer 15b can be formed by alternately irradiating one beam at a time.
- the phase shift film 15 composed of such a multilayer film has a reflectance of 1 to 30% with respect to the EUV light, and a phase difference between the reflected light from the phase shift film 15 and the reflected light from the multilayer reflective film 13 is 170 to 190. It is formed to be a degree.
- the film thickness of the phase shift film 15 is determined according to the type of metal material used for each layer and the design value of the reflectance of EUV light, and so that the refractive index and the film thickness satisfy a predetermined relationship.
- the thickness of the phase shift film 15 is 100 nm or less, preferably 30 to 90 nm.
- the film thicknesses of the first layer 15a and the second layer 15b, etc., in the phase shift film 15 made of a multilayer film are the wavelength of EUV light, the number of layers of the multilayer film, the type of material of each layer, its cleaning resistance and processing. It is determined by an appropriate combination of film thicknesses in consideration of characteristics such as properties.
- the film thickness ratio between the first layer 15a and the second layer 15b of the unit thin film 18 is determined so that the refractive index and the film thickness of each layer satisfy a predetermined relationship such as the above-described equations (1) to (3). .
- the film thickness ratio between the first layer 15a and the second layer 15b can be appropriately determined so as to satisfy a predetermined relationship according to the metal material used.
- the metal material used for example, in the case of Ta: Mo, it is preferably 20: 1 to 1: 5.
- the Ta layer is thick and the Mo layer is too thin, there is an inconvenience that the entire thickness of the phase shift film 15 for obtaining the phase shift effect is increased. Further, since Mo is easily oxidized, when the Ta layer is thin and the Mo layer is too thick, there is a disadvantage that the cleaning resistance of the entire phase shift film 15 is lowered.
- phase shift film 15 composed of a multilayer film is preferably performed continuously from the start of film formation to the end of film formation without being exposed to the atmosphere.
- the phase shift film 15 is preferably formed by an ion beam sputtering method useful for continuously forming each layer (for example, the first layer 15a and the second layer 15b) with a very thin film thickness.
- it can also be formed by a known method such as DC sputtering or RF sputtering.
- each layer of the phase shift film 15 such as Ta ⁇ Mo (for example, the first layer) is formed through the formation of the MoSi multilayer reflective film 13, the Ru protective film 14, and the like.
- the film can be formed without taking out from the sputtering apparatus until the formation of the layer 15a and the second layer 15b). Since these films are not exposed to the atmosphere, it is advantageous in that the number of defects in each film can be suppressed.
- the surface roughness of the phase shift film 15 after film formation is preferably the root mean square roughness (RMS) of 0.5 nm or less, more preferably 0.4 nm or less, and More preferably, it is 3 nm or less.
- RMS root mean square roughness
- an etching mask film (not shown) can be further formed on the phase shift film 15.
- the etching mask film has an etching selectivity with respect to the uppermost layer 16 of the multilayer reflective film 13, and the uppermost layer 16 of the phase shift film 15 can be etched with an etching gas for the first layer 15a (etching selectivity).
- the etching mask film is formed of a material containing Cr or Ta, for example.
- the material containing Cr include Cr metal alone and Cr-based compounds obtained by adding one or more elements selected from elements such as O, N, C, H, and B to Cr.
- Materials containing Ta include Ta metal alone, TaB alloy containing Ta and B, Ta alloy containing Ta and other transition metals (for example, Hf, Zr, Pt, W), Ta metal, and alloys thereof. Examples thereof include Ta compounds to which N, O, H, and / or C are added.
- a material containing Cr is selected as a material for forming the etching mask film.
- the etching mask film can be formed by a known method such as a DC sputtering method or an RF sputtering method.
- the thickness of the etching mask film is preferably 5 nm or more from the viewpoint of securing the function as a hard mask.
- the etching mask film is preferably removed simultaneously with the phase shift film 15 by the fluorine-based gas used in the etching process of the phase shift film 15. Therefore, it is preferable that the etching mask film has a film thickness approximately equal to that of the phase shift film 15.
- the film thickness of the etching mask film is 5 nm to 20 nm, preferably 5 nm to 15 nm.
- a back surface conductive film 11 for an electrostatic chuck is formed on the back surface side of the substrate 12 (the side opposite to the surface on which the multilayer reflective film 13 is formed).
- the electrical characteristics required for the back surface conductive film 11 for the electrostatic chuck are normally a sheet resistance of 100 ⁇ / sq or less.
- the back surface conductive film 11 can be formed by, for example, a magnetron sputtering method or an on-beam sputtering method using a target of a metal such as chromium or tantalum, or an alloy thereof.
- the back surface conductive film 11 is formed of, for example, CrN, it can be formed by the above sputtering method in a gas atmosphere containing N such as nitrogen gas using a Cr target.
- the thickness of the back conductive film 11 is not particularly limited as long as it satisfies the function for an electrostatic chuck, but is usually 10 to 200 nm.
- the reflective mask blank 10 of the present invention is not limited to the embodiment described above.
- the reflective mask blank 10 of the present invention can include a resist film having a function as an etching mask on the phase shift film 15.
- the reflective mask blank 10 of the present invention can include the phase shift film 15 in contact with the multilayer reflective film 13 without including the protective film 14 on the multilayer reflective film 13.
- the present invention is a reflective mask having a phase shift film pattern in which the phase shift film 15 in the reflective mask blank 10 of the present invention is patterned.
- the reflective mask blank 10 of the present invention described above can be used to produce the reflective mask of the present invention.
- a photolithography method that can perform high-definition patterning is most suitable.
- a resist film (not shown) is formed on the outermost surface (uppermost layer 16 of the phase shift film 15) of the reflective mask blank 10 shown in FIG.
- the film thickness of the resist film can be set to 100 nm, for example.
- a desired pattern is drawn (exposed) on the resist film, and further developed and rinsed to form a predetermined resist pattern (not shown).
- phase shift film 15 (multilayer film) is dry-etched with an etching gas containing a fluorine-based gas such as SF 6 by using a resist pattern (not shown) as a mask, so that the phase shift film pattern ( (Not shown).
- the resist pattern (not shown) is removed.
- the etching rate of the phase shift film 15 depends on conditions such as a material for forming the phase shift film 15 and an etching gas. In the case of the phase shift film 15 made of a multilayer film of different materials, the etching rate varies slightly for each layer of different materials. However, since the thickness of each layer is small, the etching rate in the entire phase shift film 15 is considered to be substantially constant.
- the phase shift film pattern is formed by the above process.
- Each layer (for example, the first layer 15a and the second layer 15b) of the phase shift film 15 formed of a multilayer film can be continuously etched by dry etching using one kind of etching gas. In that case, the effect of process simplification can be obtained.
- wet cleaning using an acidic or alkaline aqueous solution is performed to obtain a reflective mask for EUV lithography that has achieved high reflectivity.
- Etching gases include SF 6 , CHF 3 , CF 4 , C 2 F 6 , C 3 F 6 , C 4 F 6 , C 4 F 8 , CH 2 F 2 , CH 3 F, C 3 F 8 and fluorine gas such as F, and a mixed gas containing these fluorine gas and O 2 at a predetermined ratio can be used.
- fluorine gas such as F
- a mixed gas containing these fluorine gas and O 2 at a predetermined ratio can be used.
- other gases may be used as long as they are useful gases for processing.
- a chlorine-based gas such as Cl 2 , SiCl 4 , CHCl 3 , CCl 4 , BCl 3 , a mixed gas thereof, a mixed gas containing a chlorine-based gas and He at a predetermined ratio, a chlorine-based gas And a mixed gas containing Ar at a predetermined ratio, a halogen gas containing at least one selected from fluorine gas, chlorine gas, bromine gas and iodine gas, and at least one selected from the group consisting of hydrogen halide gas Can be mentioned. Furthermore, the mixed gas containing these gas and oxygen gas etc. are mentioned.
- phase shift film has a two-layer structure of the uppermost layer 16 and the lower layer 17 and the lower layer 17 is formed of a material having etching resistance with respect to the uppermost layer 16, two types of etching gases described above are used. It is also possible to perform dry etching in stages.
- the present invention is a method for manufacturing a semiconductor device, including a pattern forming step of forming a pattern on a semiconductor substrate 12 using the above-described reflective mask of the present invention.
- a transfer pattern based on the phase shift film pattern of the reflective mask can be formed on a semiconductor substrate by EUV lithography. Thereafter, through various other processes, a semiconductor device in which various patterns and the like are formed on the semiconductor substrate can be manufactured.
- a known pattern transfer apparatus can be used for forming the transfer pattern.
- a reflective mask having a phase shift film pattern in which the film thickness dependence of retardation is small can be used. Therefore, a semiconductor device having a fine and highly accurate transfer pattern can be obtained. Can be manufactured.
- Example 1 ⁇ Production of reflective mask blank 10> A reflective mask blank 10 of Example 1 was produced by the method described below.
- the reflective mask blank 10 of Example 1 has a structure of CrN back surface conductive film ⁇ substrate 12 ⁇ MoSi multilayer reflective film 13 ⁇ Ru protective film 14 ⁇ phase shift film 15.
- a SiO 2 —TiO 2 glass substrate 12 was prepared.
- a multilayer reflective film 13 was formed on the main surface of the substrate 12 opposite to the side on which the back conductive film 11 was formed.
- a Mo / Si periodic multilayer reflective film 13 suitable for 13.5 nm EUV light was employed as the multilayer reflective film 13 formed on the substrate 12.
- the multilayer reflective film 13 was formed by alternately stacking Mo layers and Si layers on the substrate 12 by ion beam sputtering (Ar gas atmosphere) using a Mo target and a Si target.
- a Si film was formed with a film thickness of 4.2 nm, and then a Mo film was formed with a film thickness of 2.8 nm. This was set as one period, and 40 periods were laminated in the same manner.
- a Si film was formed with a film thickness of 4.0 nm to form a multilayer reflective film 13 (total film thickness: 284 nm).
- a protective film 14 containing Ru was formed to a thickness of 2.5 nm on the uppermost Si film of the multilayer reflective film 13 by ion beam sputtering (Ar gas atmosphere) using a Ru target.
- phase shift film 15 having a two-layer structure was formed on the protective film 14 by the following method.
- the uppermost layer 16 was formed as follows. That is, RF sputtering using a SiO 2 target was performed in an Ar gas atmosphere to form an uppermost layer 16 made of a SiO 2 film having a thickness of 4 nm on the lower layer 17.
- Table 1 shows the refractive index (n 1 ) and film thickness (d 1 ) of the SiO 2 film of the uppermost layer 16 (first layer 15a) of the phase shift film 15 of Example 1, and the lower layer 17 (second layer 15b).
- the refractive index (n 2 ) and film thickness (d 2 ) of the TaN film are shown. Since the phase shift film 15 according to the first embodiment includes the pair of the uppermost layer 16 and the lower layer 17, the period is 1. The number of cycles is the same in the following Examples 2 to 4 and Comparative Examples 1 and 2.
- Example 2 As Example 2, the film thickness d 1 of the uppermost layer 16 (SiO 2 film) of the phase shift film 15 is 3.375 nm, and the film thickness d 2 of the TaN film of the lower layer 17 is 60 nm. Then, a reflective mask blank 10 was produced. Table 1 shows the refractive index (n 1 ) and film thickness (d 1 ) of the SiO 2 film of the uppermost layer 16 of the phase shift film 15 of Example 2, and the refractive index (n 2 ) and film of the TaN film of the lower layer 17. Thickness (d 2 ) is indicated.
- Example 3 Example 3, except that the thickness d 1 of the uppermost layer 16 of the phase shift film 15 (SiO 2 film) 3.7 nm, the film thickness d 2 of the TaN film of the lower layer 17 and 60nm, similarly to Example 1 Then, a reflective mask blank 10 was produced.
- Table 1 shows the refractive index (n 1 ) and film thickness (d 1 ) of the SiO 2 film of the uppermost layer 16 of the phase shift film 15 of Example 3, and the refractive index (n 2 ) and film of the TaN film of the lower layer 17. Thickness (d 2 ) is indicated.
- Example 4 is the same as Example 1 except that the film thickness d 1 of the uppermost layer 16 (SiO 2 film) of the phase shift film 15 is 18 nm and the film thickness d 2 of the TaN film of the lower layer 17 is 61.5 nm. Then, a reflective mask blank 10 was produced. Table 1 shows the refractive index (n 1 ) and film thickness (d 1 ) of the SiO 2 film of the uppermost layer 16 of the phase shift film 15 of Example 4, and the refractive index (n 2 ) and film of the TaN film of the lower layer 17. Thickness (d 2 ) is indicated.
- Comparative Example 1 As Comparative Example 1, the reflective mask is the same as in Example 1 except that the uppermost layer 16 (SiO 2 film) of the phase shift film 15 is not provided and the film thickness d 2 of the lower layer 17 (TaN film) is 65 nm. A blank 10 was produced. Table 1 shows the refractive index (n 2 ) and film thickness (d 2 ) of the TaN film in the lower layer 17 of the phase shift film 15 of Comparative Example 1.
- Comparative Example 2 As Comparative Example 1, the film thickness d 1 of the uppermost layer 16 (SiO 2 film) of the phase shift film 15 is 1.5 nm, and the film thickness d 2 of the lower layer 17 (TaN film) is 65 nm. Similarly, a reflective mask blank 10 was produced. Table 1 shows the refractive index (n 1 ) and film thickness (d 1 ) of the SiO 2 film of the uppermost layer 16 of the phase shift film 15 of Comparative Example 1, and the refractive index (n 2 ) and film of the TaN film of the lower layer 17. Thickness (d 2 ) is indicated.
- the values of 4 ⁇ (2m + 1) ⁇ 1.5 (nm) and ⁇ / 4 ⁇ (2m + 1) +1.5 (nm) are shown.
- n 1 and n 2 in Examples 1 to 4 satisfy the relationship of the above-described formula (1).
- Table 2 shows the product (n 1 ⁇ d 1 ) of n 1 and d 1 of Comparative Example 2, and ⁇ / 4 ⁇ (2m + 1) ⁇ 1.
- FIG. 3 shows the relationship between the thickness of the phase shift film 15 of Examples 1 to 4 and Comparative Examples 1 and 2 and the phase difference obtained by simulation.
- the phase difference means light in which part of the exposure light incident on the phase shift film pattern is reflected by the multilayer reflective film 13 and light in which the exposure light incident on the part without the phase shift film pattern is reflected.
- the phase difference between and.
- Examples 1 to 4 and Comparative Examples 1 and 2 the reflected light from the outermost surface of the phase shift film 15 and the reflected light from the multilayer reflective film 13 existing under the phase shift film 15 are used. It can be understood that a vibration structure is generated in the film thickness dependence of the phase difference due to the interference with the above.
- FIG. 4 shows the relationship between the thickness of the phase shift film 15 in Examples 1 to 4 and Comparative Examples 1 and 2 near the phase difference of 180 degrees and the phase difference.
- 4 is an enlarged view of Example 1 and Comparative Example 1 of FIG.
- FIG. 4 shows a film thickness range in which the phase difference variation is 10 degrees (175 degrees to 185 degrees) in Example 1 and Comparative Example 1.
- the film thickness range in which the phase difference variation was 10 degrees was 4.6 nm.
- Comparative Example 1 the film thickness at 175 degrees was 64.6 nm, and the film thickness at 185 degrees was 65.4 nm.
- the film thickness range where the phase difference variation was 10 degrees was 0.8 nm. .
- the values shown in Table 2 were obtained.
- the region where the phase difference is the best within the range of 160 degrees to 200 degrees is selected, and may include extreme values.
- the film thickness range in which the phase difference variation selected from the range of the phase difference of 160 to 200 degrees is 10 degrees is 4.0 nm or more and is wide. The range was shown.
- Example 1 does not include an extreme value in a region where the phase difference variation is 10 degrees, the phase difference variation is the most stable among Examples 1 to 4.
- the film thickness range in which the phase difference variation selected from the range of 160 to 200 degrees in Comparative Examples 1 and 2 is 10 degrees is 0.8 nm, indicating a narrow range. This means that, in the case of the reflective mask blanks 10 of Examples 1 to 4, the film thickness dependence of the phase difference at a phase difference of 160 to 200 degrees which is a desired phase shift is small.
- Example 5 (When Phase Shift Film 15 is a Multilayer Film) Next, as Example 5, a reflective mask blank 10 was manufactured in the same manner as in Example 1 except that a multilayered phase shift film 15 was formed on the protective film 14 by the following method.
- a Mo layer (second layer 15b) is first formed to a thickness of 2.4 nm by ion beam sputtering (Ar gas atmosphere) using a Mo target and a Ta target.
- a Ta layer (first layer 15a) was formed to a film thickness of 2.4 nm (film thickness ratio 1: 1).
- the phase shift film 15 having a total film thickness of 48 nm (film configuration: Mo ⁇ Ta ⁇ Mo) is formed with this period as one period, and 10 periods are continuously formed, and the uppermost layer 16 is a Ta layer (first layer 15a). ⁇ Ta ⁇ ... Mo ⁇ Ta).
- the phase shift film 15 of Example 5 has a structure having 10 periods of unit thin films 18 composed of a Ta layer (first layer 15a) and a Mo layer (second layer 15b).
- Table 3 shows the refractive index (n 1 ) and film thickness (d 1 ) of the Ta film of the uppermost layer 16 of the phase shift film 15 of Example 5, and the refractive index (n 2 ) of the Mo film formed as the lower layer 17.
- the film thickness (d 2 ) is shown.
- Example 6 As Example 6, a reflective mask blank 10 was produced in the same manner as Example 5 except that the number of periods of the phase shift film 15 was set to 15. Therefore, the phase shift film 15 of Example 5 has a structure having 15 unit thin films 18 composed of a Ta layer (first layer 15a) and a Mo layer (second layer 15b). Table 3 shows the refractive index (n 1 ) and film thickness (d 1 ) of the Ta film of the uppermost layer 16 of the phase shift film 15 of Example 6, and the refractive index (n 2 ) of the Mo film formed as the lower layer 17. The film thickness (d 2 ) is shown.
- Example 7 As Example 7, a reflective mask blank 10 was produced in the same manner as Example 5 except that the number of periods of the phase shift film 15 was set to 20. Therefore, the phase shift film 15 of Example 5 has a structure having 20 periods of unit thin films 18 composed of a Ta layer (first layer 15a) and a Mo layer (second layer 15b).
- Table 3 shows the refractive index (n 1 ) and film thickness (d 1 ) of the Ta film of the uppermost layer 16 of the phase shift film 15 of Example 7, and the refractive index (n 2 ) of the Mo film formed as the lower layer 17. The film thickness (d 2 ) is shown.
- FIG. 6 shows the relationship between the thickness of the phase shift film 15 in Examples 5 to 7 and the phase difference.
- the film thickness at which the phase difference variation selected from the range of the phase difference of 160 to 200 degrees is 10 degrees. Range was calculated. The results are shown in Table 4.
- the film thickness range in which the phase difference variation selected from the range of 160 to 200 degrees in Examples 5 to 7 is 10 degrees is 4.9 nm or more. As in the case of 1-4, a wide range was shown. This means that, in the case of the reflective mask blanks 10 of Examples 5 to 7, the film thickness dependence of the phase difference at a desired phase shift of 160 to 200 degrees is small. In addition, since Examples 5 to 7 did not include an extreme value in a region where the phase difference variation was 10 degrees, the phase difference variation was particularly stable as in Example 1.
- a resist film was formed with a film thickness of 100 nm on the phase shift film 15 of the reflective mask blanks 10 of Examples 1 to 7 manufactured as described above, and a resist pattern was formed by drawing and development. Thereafter, using this resist pattern as a mask, the phase shift film 15 was dry-etched using a fluorine-based SF 6 gas to form a phase shift film pattern. Thereafter, the resist pattern was removed to produce a reflective mask.
- the reflective mask manufactured using the mask blank substrate 120 of Examples 1 to 7 can use a reflective mask having the phase shift film 15 having a small dependence of retardation on the film thickness.
- a semiconductor device having an accurate transfer pattern could be manufactured.
- This resist pattern is transferred to the film to be processed by etching, and through various processes such as formation of an insulating film, conductive film, introduction of dopant, or annealing, a semiconductor device having desired characteristics is manufactured at a high yield. We were able to.
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Abstract
Description
本発明の構成1は、基板上に、多層反射膜と、EUV光の位相をシフトさせる位相シフト膜とがこの順に形成された反射型マスクブランクであって、
前記位相シフト膜は、最上層と、最上層以外の下層とを有し、
n2<n1<1 ・・・(1)、かつ
λ/4×(2m+1)-α≦n1・d1≦λ/4×(2m+1)+α ・・・(2)
の関係を満たすことを特徴とする反射型マスクブランクである。ただし、上記式中、n1は前記最上層の露光波長λ=13.5nmにおける屈折率、n2は前記下層の露光波長λ=13.5nmにおける屈折率、d1は前記最上層の膜厚(nm)、mはゼロ以上の整数、及びα=1.5nmである。
本発明の構成2は、前記mは2以下であることを特徴とする構成1の反射型マスクブランクである。
本発明の構成3は、前記位相シフト膜の前記最上層はケイ素化合物を含む材料からなり、前記下層はタンタル化合物を含む材料からなることを特徴とする構成1又は2の反射型マスクブランクである。
本発明の構成4は、基板上に、多層反射膜と、EUV光の位相をシフトさせる位相シフト膜とがこの順に形成された反射型マスクブランクであって、
前記位相シフト膜は、第1層~第N層(Nは2以上の整数)をこの順で含む単位薄膜を1層、又は2層以上含む多層膜からなり、最も多層反射膜から遠い所に位置する単位薄膜の第1層が最上層であり、
の関係を満たすことを特徴とする反射型マスクブランクである。ただし、上記式中、iは1~Nの整数、niは第i層の露光波長λ=13.5nmにおける屈折率、diは前記第i層の膜厚(nm)、及びα=1.5nmである。
本発明の構成5は、ni+1<ni、かつn1<1であることを特徴とする構成4の反射型マスクブランクである。
本発明の構成6は、N=2であることを特徴とする構成4又は5の反射型マスクブランクである。
本発明の構成7は、前記第1層は、Ta及びCrから選択される少なくとも一種の金属材料を含むことを特徴とする構成4~6の何れかの反射型マスクブランクである。
本発明の構成8は、前記第2層は、Mo、Ru、Pt、Pd、Ag及びAuから選択される少なくとも一種の金属材料を含むことを特徴とする構成4~7の何れかの反射型マスクブランクである。
本発明の構成9は、前記多層反射膜と前記位相シフト膜との間に保護膜を有することを特徴とする構成1~8の何れかの反射型マスクブランクである。
本発明の構成10は、構成1~9の何れかの反射型マスクブランクにおける前記位相シフト膜がパターニングされた位相シフト膜パターンを有することを特徴とする反射型マスクである。
本発明の構成11は、構成10の反射型マスクを用いて半導体基板上にパターンを形成するパターン形成工程を含むことを特徴とする半導体装置の製造方法である。
n2<n1<1 ・・・(1)、かつ
λ/4×(2m+1)-α≦n1・d1≦λ/4×(2m+1)+α ・・・(2)
を満たす。ただし、上記式(1)及び式(2)中、n1は前記最上層16の露光波長λ=13.5nmにおける屈折率、n2は下層17の露光波長λ=13.5nmにおける屈折率、d1は最上層16の膜厚、mはゼロ以上の整数、及びα=1.5である。図1に示す反射型マスクブランク10は、1層の下層17を有する。
を満たす。ただし、上記式(3)中、iは1~Nの整数、niは、第i層(iは1以上N以下の任意の整数)の露光波長λ=13.5nmにおける屈折率、diは、前記第i層の膜厚(nm)、及びα=1.5nmである。
図1は、本発明の実施形態1のEUVリソグラフィ用反射型マスクブランク10の構成を説明するための断面模式図である。図2は、本発明の実施形態2のEUVリソグラフィ用反射型マスクブランク10の構成を説明するための断面模式図である。図1及び図2を用いて本発明の反射型マスクブランク10について説明する。
本発明は、上述の本発明の反射型マスクブランク10における位相シフト膜15がパターニングされた位相シフト膜パターンを有する反射型マスクである。上述の本発明の反射型マスクブランク10を使用して、本発明の反射型マスクを作製することができる。EUVリソグラフィ用反射型マスクの製造には、高精細のパターニングを行うことができるフォトリソグラフィ法が最も好適である。
本発明は、上述の本発明の反射型マスクを用いて半導体基板12上にパターンを形成するパターン形成工程を含む、半導体装置の製造方法である。
<反射型マスクブランク10の作製>
次に述べる方法で、実施例1の反射型マスクブランク10を作製した。実施例1の反射型マスクブランク10は、CrN裏面導電膜\基板12\MoSi多層反射膜13\Ru保護膜14\位相シフト膜15という構造を有する。
実施例2として、位相シフト膜15の最上層16(SiO2膜)の膜厚d1を3.375nm、下層17のTaN膜の膜厚d2を60nmとした以外は、実施例1と同様に、反射型マスクブランク10を作製した。表1に、実施例2の位相シフト膜15の最上層16のSiO2膜の屈折率(n1)及び膜厚(d1)、並びに下層17のTaN膜の屈折率(n2)及び膜厚(d2)を示す。
実施例3として、位相シフト膜15の最上層16(SiO2膜)の膜厚d1を3.7nm、下層17のTaN膜の膜厚d2を60nmとした以外は、実施例1と同様に、反射型マスクブランク10を作製した。表1に、実施例3の位相シフト膜15の最上層16のSiO2膜の屈折率(n1)及び膜厚(d1)、並びに下層17のTaN膜の屈折率(n2)及び膜厚(d2)を示す。
実施例4として、位相シフト膜15の最上層16(SiO2膜)の膜厚d1を18nm、下層17のTaN膜の膜厚d2を61.5nmとした以外は、実施例1と同様に、反射型マスクブランク10を作製した。表1に、実施例4の位相シフト膜15の最上層16のSiO2膜の屈折率(n1)及び膜厚(d1)、並びに下層17のTaN膜の屈折率(n2)及び膜厚(d2)を示す。
比較例1として、位相シフト膜15の最上層16(SiO2膜)を設けず、下層17(TaN膜)の膜厚d2を65nmとした以外は、実施例1と同様に、反射型マスクブランク10を作製した。表1に、比較例1の位相シフト膜15の下層17のTaN膜の屈折率(n2)及び膜厚(d2)を示す。
比較例1として、位相シフト膜15の最上層16(SiO2膜)の膜厚d1を1.5nm、下層17(TaN膜)の膜厚d2を65nmとした以外は、実施例1と同様に、反射型マスクブランク10を作製した。表1に、比較例1の位相シフト膜15の最上層16のSiO2膜の屈折率(n1)及び膜厚(d1)、並びに下層17のTaN膜の屈折率(n2)及び膜厚(d2)を示す。
表2に、実施例1~4の反射型マスクブランク10のn1とd1との積(n1・d1)、並びに露光波長λ=13.5nm及びm=0のときの、λ/4×(2m+1)-1.5(nm)及びλ/4×(2m+1)+1.5(nm)の値を示す。表2から明らかなように、実施例1~4のn1及びn2は、上述の式(1)の関係を満たしている。また、実施例1~3のn1・d1は、及びm=0の場合の上述の式(2)の関係を満たしている。また、実施例4のn1・d1は、m=2の場合の上述の式(2)の関係を満たしている。
次に、実施例5として、保護膜14上に、以下の方法で多層膜からなる位相シフト膜15を形成した以外は実施例1と同様に、反射型マスクブランク10を製造した。
実施例6として、位相シフト膜15の周期の数を15とした以外は、実施例5と同様に、反射型マスクブランク10を作製した。したがって、実施例5の位相シフト膜15は、Ta層(第1層15a)及びMo層(第2層15b)からなる単位薄膜18を15周期有する構造である。表3に、実施例6の位相シフト膜15の最上層16のTa膜の屈折率(n1)及び膜厚(d1)、並びに下層17として形成したMo膜の屈折率(n2)及び膜厚(d2)を示す。
実施例7として、位相シフト膜15の周期の数を20とした以外は、実施例5と同様に、反射型マスクブランク10を作製した。したがって、したがって、実施例5の位相シフト膜15は、Ta層(第1層15a)及びMo層(第2層15b)からなる単位薄膜18を20周期有する構造である。表3に、実施例7の位相シフト膜15の最上層16のTa膜の屈折率(n1)及び膜厚(d1)、並びに下層17として形成したMo膜の屈折率(n2)及び膜厚(d2)を示す。
表4に、実施例5~7の反射型マスクブランクのn1とd1との積(n1・d1)、n2とd2との積(n2・d2)、n1・d1及びn2・d2の和、並びに露光波長λ=13.5nm及びm=2のときの、λ/4×(2m+1)-1.5(nm)及びλ/4×(2m+1)+1.5(nm)の値を示す。表2から明らかなように、実施例5~7のn1・d1及びn2・d2の和は、m=2の場合の上述の式(3)の関係を満たしている。なお、実施例5~7は、ni+1<ni(すなわち、n2<n1)、かつn1<1との関係も満たしている。
次に、上述のようにして製造した実施例1~7の反射型マスクブランク10の位相シフト膜15上に、レジスト膜を膜厚100nmで形成し、描画・現像によりレジストパターンを形成した。その後、このレジストパターンをマスクとし、フッ素系のSF6ガスを用いて、位相シフト膜15をドライエッチングし、位相シフト膜パターンを形成した。その後、レジストパターンを除去して、反射型マスクを作製した。
実施例1~7のマスクブランク用基板12を用いて製造した反射型マスクをEUVスキャナにセットし、半導体基板12上に被加工膜とレジスト膜が形成されたウエハに対してEUV露光を行った。そして、この露光済レジスト膜を現像することによって、被加工膜が形成された半導体基板12上にレジストパターンを形成した。
12 基板
13 多層反射膜
14 保護膜
15 位相シフト膜
15a 第1層
15b 第2層
16 最上層
17 下層
18 単位薄膜
Claims (11)
- 基板上に、多層反射膜と、EUV光の位相をシフトさせる位相シフト膜とがこの順に形成された反射型マスクブランクであって、
前記位相シフト膜は、最上層と、最上層以外の下層とを有し、
n2<n1<1 ・・・(1)、かつ
λ/4×(2m+1)-α≦n1・d1≦λ/4×(2m+1)+α ・・・(2)
の関係を満たすことを特徴とする反射型マスクブランク。
(ただし、n1は、前記最上層の露光波長λ=13.5nmにおける屈折率、
n2は前記下層の露光波長λ=13.5nmにおける屈折率、
d1は前記最上層の膜厚(nm)、
mはゼロ以上の整数、及び
α=1.5nm) - 前記mは2以下であることを特徴とする請求項1に記載の反射型マスクブランク。
- 前記位相シフト膜の前記最上層はケイ素化合物を含む材料からなり、前記下層はタンタル化合物を含む材料からなることを特徴とする請求項1又は2に記載の反射型マスクブランク。
- ni+1<ni、かつn1<1であることを特徴とする請求項4に記載の反射型マスクブランク。
- N=2であることを特徴とする請求項4又は5に記載の反射型マスクブランク。
- 前記第1層は、Ta及びCrから選択される少なくとも一種の金属材料を含むことを特徴とする請求項4~6の何れか一項に記載の反射型マスクブランク。
- 前記第2層は、Mo、Ru、Pt、Pd、Ag及びAuから選択される少なくとも一種の金属材料を含むことを特徴とする請求項4~7の何れか一項に記載の反射型マスクブランク。
- 前記多層反射膜と前記位相シフト膜との間に保護膜を有することを特徴とする請求項1~8の何れか一項に記載の反射型マスクブランク。
- 請求項1~9の何れか一項に記載の反射型マスクブランクにおける前記位相シフト膜がパターニングされた位相シフト膜パターンを有することを特徴とする反射型マスク。
- 請求項10に記載の反射型マスクを用いて半導体基板上にパターンを形成するパターン形成工程を含むことを特徴とする半導体装置の製造方法。
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WO2022191042A1 (ja) * | 2021-03-09 | 2022-09-15 | 株式会社トッパンフォトマスク | 位相シフトマスクブランク、位相シフトマスク、位相シフトマスクの製造方法及び位相シフトマスクの修正方法 |
WO2023190696A1 (ja) * | 2022-03-29 | 2023-10-05 | 株式会社トッパンフォトマスク | 反射型フォトマスクブランク及び反射型フォトマスク |
US11914281B2 (en) | 2018-12-27 | 2024-02-27 | Hoya Corporation | Reflective mask blank, reflective mask, and method for manufacturing semiconductor device |
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TWI775442B (zh) | 2022-08-21 |
TW202134776A (zh) | 2021-09-16 |
JP6739960B2 (ja) | 2020-08-12 |
KR20180129838A (ko) | 2018-12-05 |
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SG11201807251SA (en) | 2018-09-27 |
US10871707B2 (en) | 2020-12-22 |
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