Reflective mask blank, reflective mask, and method for manufacturing a reflective mask

Abstract

To provide a reflection type mask blank, a reflection type mask and a method for manufacturing a reflection type mask which avoid phase defects formed in a multilayer reflection layer and enable formation of a pattern without causing defects accompanied by formation of a fiducial mark.SOLUTION: A reflection type mask blank 100 with a fiducial mark has at least a multilayer reflection layer 15 and an absorption layer 13 on a substrate 16, wherein the fiducial mark has a size in plan view formed in the multilayer reflection layer of 600 nm or less, and is formed of a part 19 having light reflectance different from that of the multilayer reflection layer.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a reflective mask blank, a reflective mask, and a method for manufacturing a reflective mask, and in particular to a photomask blank and photomask, and a method for manufacturing a photomask, which are used in semiconductor manufacturing equipment and the like that employs EUV lithography using extreme ultraviolet (hereinafter referred to as "EUV") as a light source. [Background technology]

[0002] In recent years, with the miniaturization of semiconductor devices, EUV lithography using EUV with a wavelength of around 13.5 nm as a light source has been proposed. EUV lithography needs to be performed in a vacuum because the light source has a short wavelength and is highly absorptive. In addition, in the EUV wavelength region, the refractive index of most materials is slightly smaller than 1, so EUV lithography cannot use the conventionally used transmissive refractive optical system, and a reflective optical system is used. Therefore, the photomask (hereinafter also referred to as the mask) that serves as the original needs to be a reflective mask because a conventional transmissive mask cannot be used.

[0003] In EUV lithography, which has an extremely short wavelength, it is necessary to minimize the generation of particles when forming a multi-layer reflective layer on a low-thermal expansion substrate. This is because, due to the short wavelength of the exposure light, minute unevenness defects in the multi-layer reflective layer have a significant impact on the quality of the pattern transferred onto the wafer. These minute unevenness defects are called phase defects, and even if they are only a few nm in height, they have an unacceptable effect on the dimensional error of fine LSI patterns.

[0004] The causes of such minute irregularity defects are irregularities or foreign matter on the surface of the low-thermal expansion substrate, or foreign matter that has fallen during deposition of the multilayer reflective layer. The multilayer reflective layer deposited on such a foreign matter generates a local phase difference compared to the surrounding multilayer reflective layer, and is therefore also called a phase defect, which adversely affects the transfer pattern.

[0005] Although several repair methods have been proposed for such minute uneven defects (phase defects), the types of defects that can be repaired are limited, and it is difficult to repair all minute uneven defects (see, for example, Patent Document 1). Therefore, with EUV masks, it is most important to prevent the occurrence of such phase defects, but since EUV masks have a complex layer structure compared to general transmission masks, the blank quality is currently far from being defect-free.

[0006] To solve this problem, it has been proposed to inspect the position of the phase defect before forming a pattern on the EUV mask, and then form (draw) the pattern to avoid the phase defect. Specifically, by covering the phase defect with an absorbing layer, the phase defect is not transferred, and the desired pattern of reflected light without defects can be obtained from the multilayer reflective layer without an absorbing layer. Therefore, a manufacturing method that enables the creation of a high-quality reflective mask without difficult corrections is being investigated.

[0007] In order to grasp the exact position of the phase defects and to form a pattern while accurately avoiding those phase defects, it is necessary to form a reference mark called a fiducial mark on the EUV mask blank. This fiducial mark becomes the reference pattern for the blank defect inspection system (which uses DUV (Deep Ultra Violet) light or EUV light) and the mask writing system (which uses EB (Electron Beam)).

[0008] A conventional method for forming fiducial marks in an EUV mask will be described with reference to FIG. Fig. 6(a) is a schematic cross-sectional view of a reflective mask blank in which a second resist film 18 is applied onto a multilayer reflective layer 15. Next, a resist pattern for forming a fiducial mark is formed by photolithography or electron beam lithography (Fig. 6(b)), then the multilayer reflective layer 15 is engraved by etching to form a multilayer reflective layer removed portion 4 (Fig. 6(c)), and then the second resist film 18 is stripped and washed (Fig. 7(d)), and further, a protective layer 14, an absorbing layer 13, a low reflective layer 12, and a resist film 11 are sequentially laminated to form a fiducial mark 20 in the multilayer reflective layer removed portion 4, thereby completing a reflective mask blank 100' with a fiducial mark (Fig. 7(e)).

[0009] As shown in Figures 6 and 7, conventional methods for manufacturing fiducial marks require the use of photolithography or electron beam lithography to etch a multilayer reflective film, and further require the deposition of a protective layer 14, an absorbing layer 13, a low-reflective layer 12, etc., which creates the problem of increasing the number of defects despite the need to avoid the occurrence of defects as much as possible. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] JP 2010-034129 A Summary of the Invention [Problem to be solved by the invention]

[0011] Therefore, the present invention aims to solve the problems associated with the conventional formation methods as described above, and has an objective of providing a reflective mask blank, a reflective mask, and a method for manufacturing a reflective mask that are capable of forming a pattern while avoiding phase defects formed in a multilayer reflective layer without generating defects associated with the formation of fiducial marks. [Means for solving the problem]

[0012] As a means for solving the above problems, a first aspect of the present invention is a fiducial-mark-equipped EUV reflective mask blank having at least a multilayer reflective layer and an absorbing layer on a substrate, The fiducial mark is an EUV reflective mask blank with a fiducial mark, characterized in that the fiducial mark is formed in the multilayer reflective layer, has a planar size of 600 nm or less, and consists of a portion having a different light reflectance from that of the multilayer reflective layer.

[0013] A second aspect is the EUV reflective mask blank with a fiducial mark according to the first aspect, characterized in that the light reflectance of the portion is lower than the light reflectance of the multilayer reflective layer.

[0014] A third aspect is an EUV reflective mask having at least a multilayer reflective layer and an absorbing layer in this order on a substrate, a portion in the multilayer reflective layer that has a planar size of 600 nm or less and is usable as a fiducial mark and has a different light reflectance from that of the multilayer reflective layer; The EUV reflective mask is characterized in that the absorbing layer is provided with a circuit pattern in which the multilayer reflective layer is exposed by removing the absorbing layer.

[0015] A fourth aspect is the EUV reflective mask according to the third aspect, characterized in that the reflectance is lower than the reflectance of the multilayer reflective layer.

[0016] A fifth aspect is an EUV reflective mask according to the third or fourth aspect, further comprising an alignment mark on the absorption layer. It is a reflective mask for use.

[0017] A sixth aspect of the present invention relates to a reflective mask blank having at least a multilayer reflective layer on a substrate, the multilayer reflective layer being provided with a fiducial mark having a size of 600 nm or less in a plan view and a light reflectance different from that of the multilayer reflective layer; determining a relative position of a defect formed in the multilayer reflective layer from the fiducial mark; depositing at least an absorbing layer on the multilayer reflective layer; a step of plotting a circuit pattern by adjusting a pattern formation position using the fiducial mark so that the circuit pattern avoids the defect; The method for manufacturing a reflective mask is characterized in that:

[0018] A seventh aspect of the present invention relates to a reflective mask blank having at least a multilayer reflective layer on a substrate, and a method for manufacturing the same, comprising the steps of: forming a fiducial mark having a size of 600 nm or less in a plan view and a light reflectance different from that of the multilayer reflective layer in the multilayer reflective layer of the reflective mask blank; determining a relative position of a defect formed in the multilayer reflective layer from the fiducial mark; depositing at least an absorbing layer on the multilayer reflective layer; forming an alignment mark in the absorbing film; determining a relative position of the fiducial mark and the alignment mark; determining a relative position of the alignment mark and the defect; a step of drawing a circuit pattern by adjusting a pattern position using the alignment mark so that the circuit pattern avoids the defect; The method for manufacturing a reflective mask is characterized in that: Effect of the Invention

[0019] According to the EUV reflective mask blank with fiducial marks of the present invention, it is possible to form fiducial marks without requiring processes that generate dust, such as the dry etching process and thin film formation process, which are required in conventional EUV reflective mask blanks with fiducial marks, and therefore it is possible to provide an EUV reflective mask blank with fiducial marks with fewer defects.

[0020] According to the EUV reflective mask of the present invention, it is possible to provide an EUV reflective mask in which a circuit pattern is formed while reliably avoiding phase defects formed in the multi-layer reflective layer.

[0021] According to the method for producing an EUV reflective mask of the present invention, it is possible to provide an EUV reflective mask of the present invention. [Brief description of the drawings]

[0022] [Figure 1] FIG. 2 is a cross-sectional explanatory diagram illustrating an example of an EUV reflective mask blank with a fiducial mark of the present invention. [Diagram 2] 1A to 1C are cross-sectional views illustrating a method for manufacturing an EUV reflective mask according to a first embodiment of the present invention. [Diagram 3] 1A to 1C are cross-sectional views illustrating a method for manufacturing an EUV reflective mask according to a first embodiment of the present invention. [Figure 4] 5A to 5C are cross-sectional views illustrating a method for manufacturing an EUV reflective mask according to a second embodiment of the present invention. [Diagram 5] 5A to 5C are cross-sectional views illustrating a method for manufacturing an EUV reflective mask according to a second embodiment of the present invention. [Figure 6] 1A to 1C are cross-sectional explanatory views illustrating a conventional method for manufacturing a reflective mask blank with a fiducial mark. [Figure 7] 1A to 1C are cross-sectional explanatory views illustrating a conventional method for manufacturing a reflective mask blank with a fiducial mark. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] The reflective mask blank will be described with reference to FIG. 1. FIG. 1 is a schematic cross-sectional view of an example of a reflective mask blank 100 with a fiducial mark. The reflective mask blank from which such a reflective mask is based is a reflective mask blank in which a multilayer reflective layer 15, a protective layer 14, an absorbing layer 13, a low reflective layer 12, and a resist film 11 are sequentially laminated on a low thermal expansion substrate 16. In addition, a back conductive film 17 required for electrostatic chucking to a mask stage of an exposure machine is formed on the back surface of the low thermal expansion substrate 16. When processing the reflective mask blank into a reflective mask, a circuit pattern consisting of an absorbing part and a reflective part is formed by partially removing the absorbing layer by EB lithography and etching technology. The light image reflected by the reflective mask thus fabricated is transferred onto a semiconductor substrate via a reflection optical system.

[0024] In addition, the multilayer reflective layer used in EUV masks is made of Si (silicon) and Mo (molybdenum) alternately deposited with a specified thickness, and consists of 40 to 50 pairs in total (since one pair is a Si layer and a Mo layer, this corresponds to about 80 to 100 layers). Si and Mo have low absorption (extinction coefficient) for EUV light, and the difference in refractive index between Si and Mo for EUV light is large. Therefore, Si and Mo are often used because of the advantage that they can increase the reflectance at the interface between them. With this multilayer structure, EUV light can be reflected 40 times if a multilayer reflective layer consists of 40 pairs. The EUV light reflected at each interface has the same phase, and the sum of these reflectances is the EUV reflectance from the multilayer reflective layer, which is approximately 62 to 65% or more for EUV mask blanks sold by various EUV blank manufacturers, approaching the theoretical value of about 70%.

[0025] The reflectivity of an EUV mask is desired to be as high as possible because it directly affects the throughput (production capacity) of semiconductor chip manufacturing, and of the currently known materials and combinations thereof, the multi-layer reflective layer of Si and Mo mentioned above is considered to be the best. The essential ability to generate reflectivity is the interface between Si and Mo, and it is important that this interface is formed properly. For this reason, a method is used in which Si and Mo are alternately deposited in the same vacuum chamber without breaking the vacuum. The deposition method mainly used is sputtering.

[0026] <Reflective mask blank with fiducial mark> Next, a reflective mask blank with a fiducial mark according to an embodiment of the present invention will be described with reference to FIG.

[0027] The reflective mask blank 100 with a fiducial mark according to an embodiment of the present invention is an EUV reflective mask blank with a fiducial mark having at least a multilayer reflective layer 15 and an absorbing layer 13 on a substrate 16.

[0028] A fiducial mark is a mark (reference mark) formed on a reflective mask blank such as an EUV mask in order to grasp the exact position of a phase defect and to form a pattern while accurately avoiding those phase defects. This fiducial mark becomes the reference pattern for the blank defect inspection machine and the mask writing machine.

[0029] The fiducial mark is a portion 19 having a reflectance different from the surroundings in FIG. 1, and is a reference mark that can be observed when the reflective mask blank 100 with the fiducial mark is observed in plan view. In the reflective mask blank, this fiducial mark 19 is formed inside the multilayer reflective layer 15, and has a size of 600 nm or less when the reflective mask blank 100 is viewed in a plane.Since the light reflectance of the fiducial mark 19 is different from that of the multilayer reflective layer 15, the fiducial mark 19 is an observable portion.

[0030] If the size of the fiducial mark 19 in plan view exceeds 600 nm, the mark becomes too large and may overwhelm the drawn pattern, which is undesirable.

[0031] The reflectance of light at the portion 19 having a reflectance different from that of the surroundings may be lower than the reflectance of the multilayer reflective layer 15 .

[0032] The reflective mask blank 100 with a fiducial mark of the present invention may have a layer structure including a multilayer reflective layer 15, a protective layer 14, an absorbing layer 13, and a low reflective layer 12 in this order on one surface of a substrate 16. Furthermore, a resist film 11 may be provided on the low reflective layer 12.

[0033] Moreover, a back surface conductive film 17 may be formed on the other surface of the substrate 16. The back surface conductive film 17 is a necessary component for electrostatic chucking to a mask stage of an exposure machine.

[0034] (substrate) The material of the substrate 16 is required to have a low coefficient of thermal expansion of <±5 ppb / K, and the optical system of the exposure tool is designed so that EUV light with a wavelength of 13.5 nm is incident on the reflective mask at an angle of incidence of 6°. Therefore, the mask surface must have a flatness of <36 nm in peak-to-valley (PV) across the entire mask surface. Substrates made of titanium oxide-doped quartz glass are available as a material that can meet such strict specifications.

[0035] (Multi-layer reflective layer) The multilayer reflective layer 15 is a layer that reflects EUV light. It is a multilayer film in which Si (silicon) and Mo (molybdenum) are alternately deposited with a thickness of about 4.2 nm and about 2.8 nm, respectively, and a multilayer reflective layer consisting of 40 to 50 pairs in total (since one pair is a Si layer and a Mo layer, this corresponds to about 80 to 100 layers) is used. The EUV reflectance (light reflectance at the wavelength of EUV light) of about 62 to 65% is generally available.

[0036] (protective layer) The protective layer 14 is a layer provided to suppress deterioration of the multilayer reflective layer 15 due to irradiation with EUV light. There is no particular need to limit the material of the protective layer 14, but for example, Ru (ruthenium) or a Ru compound can be used. The thickness is preferably about 2 to 4 nm.

[0037] (Absorption layer) The absorbing layer 13 is a layer that absorbs EUV light and does not reflect it. The contrast between the high reflectance region of the multilayer reflective layer 15 and the low reflectance region of the absorbing layer 13 allows the EUV light to be reflected in a pattern, thereby enabling pattern formation. The material of the absorbing layer 13 does not need to be particularly limited as long as it has a high absorptivity for EUV light, a low EUV reflectivity, and is not easily degraded by EUV light. For example, Ta (tantalum) and Ta compounds are used. Examples include TaN, TaBN, TaSi, and TaGeN. In addition, the EUV reflectivity of the absorbing layer 13 is required to be about <0.5%.

[0038] (Low reflective layer) The low-reflection layer 12 is provided on the absorption layer 13 and is a low-reflection layer against DUV (deep ultraviolet) light used for pattern inspection. There is no need to limit the material of the low-reflection layer 12 in particular as long as it has a lower EUV reflectance than the absorption layer 13 and is not easily deteriorated by irradiation with EUV light. For example, an oxidized nitride layer of a Ta-based material is formed as the absorption layer 13 with a thickness of about 5 nm to 12 nm.

[0039] (resist film) The resist film 11 is not particularly limited and may be any photosensitive resist or electron beam resist used as an etching mask for a photomask.

[0040] <Method of manufacturing reflective mask> Next, a method for manufacturing a reflective mask according to an embodiment of the present invention will be described with reference to FIGS.

[0041] <First embodiment of the manufacturing method for a reflective mask> A first embodiment of the method for manufacturing a reflective mask according to the present invention will be described with reference to FIGS.

[0042] The method for manufacturing a reflective mask according to an embodiment of the present invention includes the steps of forming a fiducial mark 19 having a size of 600 nm or less in plan view and a light reflectance different from that of the multilayer reflective layer 15 in the multilayer reflective layer 15 of a reflective mask blank 10-1 having at least a multilayer reflective layer 15 on a substrate 16, grasping a relative position of a defect 1 formed in the multilayer reflective layer 15 from the fiducial mark 19, forming at least an absorption layer 13 on the multilayer reflective layer 15, and drawing a circuit pattern 3 by adjusting a pattern formation position so that the circuit pattern 3 avoids the defect 1 using the fiducial mark 19, in this order. Note that Figs. 2 and 3 show an example in which a back conductive film 17 is formed on the surface of the substrate 16 opposite to the surface on which the multilayer reflective layer 15 is formed. The back conductive film 17 is usually formed because it is necessary when performing electrostatic chucking.

[0043] (Step 1: A process of forming a portion (fiducial mark) 19 (see FIG. 2(b)) whose light reflectance is different from the reflectance of the surrounding multilayer reflective layer 15 in the multilayer reflective layer 15 of a reflective mask blank 10-1 (see FIG. 2(a)). By irradiating a femtosecond laser from the back surface of the reflective mask blank 10-1 to a predetermined position, mixing (a state in which atoms are mixed together) occurs only in the irradiated portion of the multilayer reflective layer 15, and the multilayer structure of the multilayer reflective layer 15 is disturbed to form a fiducial mark 19, which is a portion 19 (see FIG. 2(b)) with a reflectance different from the surroundings. For example, Carl Zeiss's RegC (Registration Control) (a registered trademark of Carl Zeiss) can be used as an apparatus for irradiating the femtosecond laser.

[0044] (Step 2: A step of measuring and grasping the relative position (coordinates) of defect 1 in multilayer reflective layer 15 from fiducial mark 19) Next, using a device capable of measuring the coordinates of tiny objects to be measured, such as a photomask inspection device manufactured by KLA Tencor, a defect inspection is performed using the fiducial mark (a region whose light reflectance differs from that of the surrounding multilayer reflective layer) 19 as an alignment mark, and defect 1 is detected in multilayer reflective layer 15, and its coordinates are measured and recorded, thereby determining the coordinates of all defects 1 in reflective mask blank 10-1 (see Figure 2(c)).

[0045] (Step 3: Forming the absorbing layer 13 on the multilayer reflective layer 15) Next, a protective layer (also called a capping layer) for protecting the multilayer reflective layer 15 is first formed on the multilayer reflective layer 15 by a sputtering method. Ru (ruthenium) can be used as a material for the protective layer. Next, an absorbing layer 13 for EUV light is formed by a sputtering method. Ta (tantalum) can be used as a material for the absorbing layer 13. In FIG. 3(d), the protective layer is omitted. A low reflective layer is formed on the absorbing layer 13, but the low reflective layer is also omitted in FIG. 3(d).

[0046] (Step 4: A process of drawing the circuit pattern 3 by adjusting the pattern formation position using the fiducial mark 19 so that the circuit pattern 3 avoids the defect 1) Next, a second resist film 18 is formed on the absorbing layer 13. The second resist film 18 can be formed by applying a photosensitive resist coating liquid using a coating device with good film thickness uniformity, such as a spin coater used in the manufacturing process of photomasks, and then drying the applied liquid. When a circuit pattern is drawn using an electron beam drawing device, an electron beam resist coating liquid may be used.

[0047] On the second resist film 18 thus formed, a circuit pattern 3 is written using a writing device such as an electron beam mask writing device manufactured by NuFlare Technology, Inc., and developed to pattern the second resist film 18. At this time, since the coordinates of all of the defects 1 in the multilayer reflective layer 15 relative to the fiducial marks 19 are known, the circuit pattern 3 can be written by shifting the pattern formation position so that the defects 1 in the multilayer reflective layer 15 are hidden by the absorbing layer 13 in a planar view.

[0048] Next, the non-contact layer 13 of the absorption layer 13 is etched using the patterned second resist film 18 as an etching mask. The main parts are removed by etching (see FIG. 3(e)). For example, the CENTURA 10000 series manufactured by Applied Materials was used for the etching removal. A dry etching device for photomasks such as TETRA (trademark of Applied Material) (registered trademark of Applied Material) can be used. Alternatively, a focused ion beam (NB) device manufactured by FEI may be used.

[0049] Next, the patterned second resist film 18 is removed by ashing using a resist film stripping solution or oxygen-based plasma, thereby forming the circuit pattern 3 (see FIG. 3(f)).

[0050] In this manner, the EUV reflective mask 200-1 of the present invention can be fabricated.

[0051] <Second embodiment of the manufacturing method for a reflective mask> A second embodiment of the method for manufacturing a reflective mask according to the present invention will be described with reference to FIGS. The second embodiment of the method for manufacturing a reflective mask according to the present invention is similar to the first embodiment in the steps from step 1: forming a fiducial mark 19 having a size of 600 nm or less in plan view and a light reflectance different from that of the multilayer reflective layer 15 in the multilayer reflective layer 15 of a reflective mask blank 10-1 having at least a multilayer reflective layer 15 on a substrate 16 to step 3: forming at least an absorption layer 13 on the multilayer reflective layer 15, but the steps from step 4 onwards are as follows. That is, the method includes a step of forming an alignment mark 2 on the absorption layer 13, a step of grasping the relative position of the fiducial mark 19 and the alignment mark 2, a step of determining the relative position of the alignment mark 2 and the defect 1, and a step of adjusting the pattern position using the alignment mark 2 so that the circuit pattern 3 avoids the defect 1 and drawing the circuit pattern 3, in this order. Note that Figs. 4 and 5 show an example in which a back conductive film 17 is formed on the surface of the substrate 16 opposite to the surface on which the multilayer reflective layer 15 is formed. The back surface conductive film 17 is usually formed since it is necessary when performing electrostatic chucking.

[0052] Steps 4 and beyond are explained below. (Step 4: Forming alignment marks in the absorption layer) Using photolithography, a part of the absorbing layer 13 (or the low-reflection layer and the absorbing layer 13) is etched away to form the alignment mark 2 (see FIG. 4(a)). Specifically, a photosensitive resist layer is first applied onto the absorbing layer 13 and dried, and then the alignment mark is exposed to light and developed to form a pattern in the photosensitive resist layer.

[0053] Next, the absorbing layer 13 (or the low-reflection layer and the absorbing layer 13) is dry-etched using the pattern of the photosensitive resist layer as an etching mask, and then the pattern of the photosensitive resist layer is removed to form the alignment mark 2. For the dry etching process, a dry etching device for photomasks such as CENTURA (a registered trademark of Applied Material) or TETRA (to be a registered trademark of Applied Material) manufactured by Applied Material can be used. Alternatively, the alignment mark 2 can be formed using an NB (focused ion beam) device manufactured by FEI.

[0054] (Step 5: Inspection process to determine the relative positions of the fiducial mark 19 and the alignment mark 2) Next, using a photomask inspection device manufactured by KLA Tencor, both the area (fiducial mark) 19 with a reflectivity different from the surrounding area in the multilayer reflective layer 15 produced in STEP 1 and the alignment mark 2 of the absorption layer 13 produced in STEP 4 are detected, and the relative coordinates of the two are determined (see Figure 4(b)).

[0055] (Step 6: Understanding the relative positions of alignment mark 2 and defect 1) Next, using a photomask inspection device manufactured by KLA Tencor, both the alignment mark 2 in the absorbing layer 13 produced in step 4 and the defect 1 in the multilayer reflective layer 15 are detected, and the relative coordinates of the two are obtained (see FIG. 4(c)). Then, in steps 5 and 6, the relative coordinates of the portion (fiducial mark) 19 in the multilayer reflective layer 15 produced in step 1 that has a reflectance different from the surroundings and the defect 1 in the multilayer reflective layer 15 are obtained.

[0056] (Step 7: A process of forming circuit pattern 3 by adjusting the pattern position so that circuit pattern 3 avoids defect 1) Next, a second resist film 18 is formed on the absorption layer 13 on which the alignment mark 2 is formed. The second resist film 18 can be formed by applying a photosensitive resist coating liquid using a coating device with good film thickness uniformity, such as a spin coater used in the manufacturing process of photomasks, and then drying the applied liquid. When a circuit pattern is drawn using an electron beam drawing device, an electron beam resist coating liquid may be used.

[0057] A circuit pattern 3 is drawn on the second resist film 18 thus formed using a drawing device such as an electron beam mask drawing device manufactured by NuFlare Technology, Inc., and then developed, thereby patterning the second resist film 18.

[0058] Next, unnecessary portions of the absorption layer 13 are etched away using the patterned second resist film 18 as an etching mask (see FIG. 5(d)).

[0059] Next, the patterned second resist film 18 is removed by ashing using a resist film stripping solution or oxygen-based plasma, thereby forming the circuit pattern 3 (see FIG. 5(e)).

[0060] Since the coordinates of the defect 1 in the multilayer reflective layer 15 are accurately known, the circuit pattern 3 is drawn by shifting the pattern formation position so that the defect 1 in the multilayer reflective layer 15 is hidden by the absorbing layer 13 in a plan view.

[0061] In this manner, the EUV reflective mask 200-2 according to the embodiment of the present invention can be fabricated.

[0062] <Reflective mask> Next, an EUV reflective mask according to an embodiment of the present invention will be described with reference to FIG. 3(f) and FIG. 5(e).

[0063] <First embodiment of the EUV reflective mask of the present invention> 3(f), an EUV reflective mask 200-1 in the first embodiment of the EUV reflective mask of the present invention is an EUV reflective mask including at least a multilayer reflective layer 15 and an absorbing layer 13 in this order on a substrate 16. The substrate 16 may have a layer structure including, in this order, a multilayer reflective layer 15, a protective layer 14, an absorbing layer 13, and a low-reflective layer 12 on one surface of the substrate 16. Furthermore, the substrate 16 may have, on the other surface thereof, a rear conductive film 17 that enables electrostatic chucking.

[0064] The multilayer reflective layer 15 is characterized by having a portion 19 that has a size of 600 nm or less in a plan view, is usable as a fiducial mark, and has a light reflectance different from that of the multilayer reflective layer 15 .

[0065] <Second embodiment of the EUV reflective mask of the present invention> As illustrated in FIG. 5(e), an EUV reflective mask 200-2 in the second embodiment of the EUV reflective mask of the present invention has an alignment mark 2 in addition to a circuit pattern 3 in the absorption layer 13 of the EUV reflective mask 200-1 in the first embodiment. [Explanation of symbols]

[0066] 1. Defects (in multilayer reflective layer) 2 Alignment marks 3. Circuit pattern 4...Multilayer reflective layer removed section 10, 10-1... EUV reflective mask blanks 11. Resist film 12...Low reflection layer 13. Absorption layer 14. Protective layer (or capping layer) 15...Multi-layer reflective layer 16. Low thermal expansion substrate 17 Backside conductive film 18 Second resist film 19. Areas with different reflectance from the multi-layer reflective layer (or fiducial marks) 20. Fiduciary Mark 100, 100´··· EUV Reflective Photomask Blank with Fiducial Marks nine 200-1, 200-2...EUV reflective photomask

Claims

1. A reflective mask blank with a fiducial mark, comprising at least a multilayer reflective layer and an absorbing layer on a substrate, A reflective mask blank with a fiducial mark, characterized in that the fiducial mark is formed inside the multilayer reflective layer, has a planar size of 600 nm or less, and consists of a portion having a different light reflectance from that of the multilayer reflective layer.

2. 2. The reflective mask blank with a fiducial mark according to claim 1, wherein the light reflectance of the portion is lower than the light reflectance of the multilayer reflective layer.

3. A reflective mask blank with a fiducial mark as described in claim 1 or claim 2, characterized in that in the portion, the atoms constituting the multilayer reflective layer are mixed together, thereby disrupting the layered structure of the multilayer reflective layer, compared to an area of ​​the multilayer reflective layer where the portion is not formed.

4. A reflective mask blank with a fiducial mark described in any one of claims 1 to 3, characterized in that the thickness of the multilayer reflective layer in the area where the portion is formed is the same as the thickness of the multilayer reflective layer in the area where the portion is not formed.

5. A reflective mask for EUV comprising at least a multilayer reflective layer and an absorbing layer in this order on a substrate, a portion within the multilayer reflective layer that has a size in a plan view of 600 nm or less and that is usable as a fiducial mark and has a light reflectance different from that of the multilayer reflective layer; A reflective mask comprising: a circuit pattern formed on the absorbing layer, the circuit pattern being formed by removing the absorbing layer to expose the multilayer reflective layer.

6. 6. The reflective mask according to claim 5, wherein the reflectance is lower than the reflectance of the multilayer reflective layer.

7. 7. A reflective mask according to claim 5, further comprising an alignment mark on said absorbing layer.

8. A reflective mask described in any one of claims 5 to 7, characterized in that in the portion, the atoms constituting the multilayer reflective layer are mixed together, thereby disrupting the layered structure of the multilayer reflective layer, compared to an area of ​​the multilayer reflective layer where the portion is not formed.

9. A reflective mask described in any one of claims 5 to 8, characterized in that the thickness of the multilayer reflective layer in the area where the portion is formed is the same as the thickness of the multilayer reflective layer in the area where the portion is not formed.

10. forming a fiducial mark having a size of 600 nm or less in a plan view and a light reflectance different from that of the multilayer reflective layer in a reflective mask blank having at least a multilayer reflective layer on a substrate; determining a relative position of a defect formed in the multilayer reflective layer from the fiducial mark; depositing at least an absorbing layer on the multilayer reflective layer; a step of plotting a circuit pattern by adjusting a pattern formation position using the fiducial mark so that the circuit pattern avoids the defect; 4. A method for manufacturing a reflective mask, comprising the steps of:

11. A method for manufacturing a reflective mask as described in Claim 10, characterized in that in areas where the reflectivity of light is different from that of the multilayer reflective layer, the atoms constituting the multilayer reflective layer mix together, thereby disrupting the layered structure of the multilayer reflective layer, compared to areas of the multilayer reflective layer where the areas are not formed.

12. A method for manufacturing a reflective mask as described in claim 10 or claim 11, characterized in that the thickness of the multilayer reflective layer in an area where a portion having a reflectivity different from that of the multilayer reflective layer is formed is the same as the thickness of the multilayer reflective layer in an area where no such portion is formed.

13. A method for manufacturing a reflective mask described in any one of claims 10 to 12, characterized in that the fiducial mark is formed by irradiating a laser from the substrate side toward the multilayer reflective layer side.

14. forming a fiducial mark having a size of 600 nm or less in a plan view and a light reflectance different from that of the multilayer reflective layer in a reflective mask blank having at least a multilayer reflective layer on a substrate; determining a relative position of a defect formed in the multilayer reflective layer from the fiducial mark; depositing at least an absorbing layer on the multilayer reflective layer; forming an alignment mark in the absorption layer; determining a relative position of the fiducial mark and the alignment mark; determining a relative position of the alignment mark and the defect; a step of drawing a circuit pattern by adjusting a pattern position using the alignment mark so that the circuit pattern avoids the defect; 4. A method for manufacturing a reflective mask, comprising the steps of:

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