Substrate with multilayer reflective film, mask blank, transfer mask and method for producing transfer mask

Abstract

To provide a substrate with a multilayer reflective film for producing a transfer mask that allows higher detection accuracy in an electron beam lithography device.SOLUTION: A substrate with a multilayer reflective film comprises a substrate and a multilayer reflective film arranged on the substrate, wherein a surface of the substrate with the multilayer reflective film has at least one concave mark, and when a cross-sectional profile of the mark is expressed as the function y=f(x), in the first derivative y'=f'(x) of the function y=f(x), a value T1 at x=X1 and a value T2 at x=X2 satisfy a predetermined equation.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a multilayer reflective film-coated substrate, a mask blank, a transfer mask, and a method for manufacturing a transfer mask. [Background technology]

[0002] In recent years, in the semiconductor industry, with the increasing integration of semiconductor devices, fine patterns exceeding the transfer limit of conventional photolithography using ultraviolet light are required. In order to enable the formation of such fine patterns, EUV lithography, an exposure technology using extreme ultraviolet (hereinafter referred to as "EUV") light, has been developed. Here, EUV light refers to light in a wavelength band in the soft X-ray region or the vacuum ultraviolet region, specifically light with a wavelength of about 0.2 to 100 nm. A reflective mask is used as a transfer mask in this EUV lithography. In such a reflective mask, a multilayer reflective film that reflects exposure light is formed on a substrate, and an absorber film that absorbs exposure light is formed on the multilayer reflective film. A transfer pattern is formed in the absorber film.

[0003] In a reflective mask that uses EUV light as the exposure light, it is particularly important to accurately identify the location of defects on the multilayer reflective coating, because defects present in the multilayer reflective coating are almost impossible to correct and can result in serious phase defects in the transferred pattern.

[0004] Also, a technology (Defect Mitigation Technology, referred to as "DM technology" in this specification) is used to reduce the effect of defects by correcting drawing data so that an absorber pattern is formed in a location where a defect exists based on defect data and device pattern data of a mask blank. In the DM technology, for example, in a reflective mask blank in which an absorber film is formed on a multilayer reflective film, when a pattern is drawn on a resist film formed on the absorber film using an electron beam drawing device, a reference mark is also detected by an electron beam in the electron beam drawing device. In the DM technology, a pattern is drawn on a resist film based on drawing data corrected and modified based on the reference point detected by the electron beam drawing device.

[0005] Patent Documents 1 and 2 disclose examples of multilayer reflective film-coated substrates that are provided with reference marks.

[0006] Patent Document 1 describes a multilayer reflective film-coated substrate including a substrate, a multilayer reflective film formed on the substrate for reflecting EUV light, and a protective film formed on the multilayer reflective film. Patent Document 1 describes that the protective film has a fiducial mark formed in a concave shape on its surface. Patent Document 1 describes that the surface layer of the fiducial mark contains at least one element identical to the element contained in the protective film. Patent Document 1 describes that the bottom of the fiducial mark has a shrink region in which at least some of the films contained in the multilayer reflective film have shrunk.

[0007] Patent Document 2 describes a multilayer reflective film-coated substrate including a substrate and a multilayer reflective film formed on the substrate and reflecting EUV light. Patent Document 2 describes that the multilayer reflective film-coated substrate is provided with a fiducial mark formed in a concave shape on the surface thereof. Patent Document 1 describes that the fiducial mark has a groove or protrusion substantially at the center, and that the shape of the groove or protrusion in a plan view is similar or approximately similar to the shape of the fiducial mark. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] International Publication No. 2019 / 078205 [Patent Document 2] International Publication No. 2019 / 078206 Summary of the Invention [Problem to be solved by the invention]

[0009] By using the reference mark of Patent Document 1 as an FM (fiducial mark), defect coordinates can be managed with high accuracy. For example, by detecting the FM using an electron beam lithography system, the defect coordinates can be converted into the coordinate system of the electron beam lithography system. Then, using the above-mentioned DM technique, the drawing data of the pattern drawn by the electron beam lithography system can be corrected so that the defect is positioned under the absorber pattern. This makes it possible to reduce the effect of the defect on the reflective mask that is finally manufactured.

[0010] In order to control defect coordinates with high accuracy by using the fiducial mark as an FM, as described above, the fiducial mark transferred to the absorber film and the resist film thereon must have high enough contrast to be detectable by an electron beam lithography system. Conventionally, it was thought that in order to detect the fiducial mark with higher accuracy, it was necessary to obtain higher contrast by forming a deeper fiducial mark.

[0011] On the other hand, the present inventors have found that when there are two FMs with the same width and depth, a problem may occur in that the detection accuracy of the two FMs in an electron beam lithography apparatus differs. It was thought that the deeper the FM, the higher the detection accuracy of the electron beam lithography apparatus, but this is not necessarily the case. The present inventors have found that in some cases, even if the FM is deep, the detection accuracy of the electron beam lithography apparatus may not be high.

[0012] The above-mentioned problem is not limited to FM, but also applies to various marks, such as alignment marks and ID marks, formed on multilayer reflective film-coated substrates, reflective mask blanks, and reflective masks.

[0013] Furthermore, the above-mentioned problems are not limited to multilayer reflective film-coated substrates, reflective mask blanks, and reflective masks, but are also problems that exist in transmission mask blanks and transmission masks in the same manner. That is, the above-mentioned problems exist in transfer masks such as reflective masks and transmission masks.

[0014] Therefore, an object of the present invention is to provide a mask blank and a transfer mask having marks that can be detected with higher accuracy by an electron beam lithography system, and a substrate with a multilayer reflective film for manufacturing a mask blank and a transfer mask having marks that can be detected with higher accuracy by an electron beam lithography system. [Means for solving the problem]

[0015] In order to solve the above problems, the present invention has the following configuration.

[0016] (Configuration 1) Configuration 1 is a multilayer reflective film-coated substrate having a substrate and a multilayer reflective film disposed on the substrate, the surface of the multilayer reflective film-coated substrate has at least one concave mark; The multilayer reflective film-coated substrate is characterized in that, when a cross-sectional profile of the mark is represented by a function y=f(x), in a first differential y'=f'(x) of the function y=f(x), a value T1 at x=X1 and a value T2 at x=X2 satisfy formula (1).

number

[0017] (Configuration 2) A configuration 2 is the multilayer reflective film coated substrate of configuration 1, wherein X1 satisfies -a·W≦X1≦b1, and X2 satisfies b2≦X2≦a·W. W: Mark width D: Mark depth a: constant b1: the negative position in the width direction when y=-D / 3, where the coordinate in the depth direction of the surface of the multilayer reflective film-coated substrate where the mark is not present is y=0 b2: the positive position in the width direction when y=-D / 3

[0018] (Configuration 3) Configuration 3 is the multilayer reflective film-coated substrate of configuration 2, characterized in that the width W of the mark is 0.5 to 10 μm.

[0019] (Configuration 4) Configuration 4 is the multilayer reflective film-coated substrate according to configuration 2 or 3, wherein the depth D of the mark is 10 to 80 nm.

[0020] (Configuration 5) A fifth aspect of the present invention is the multilayer reflective film-coated substrate according to any one of the first to fourth aspects, further comprising a protective film on the multilayer reflective film.

[0021] (Configuration 6) Configuration 6 is a mask blank having a substrate and a thin film for forming a pattern disposed on the substrate, the surface of the mask blank has at least one concave mark; When the cross-sectional profile of the mark is represented by a function y=f(x), The mask blank is characterized in that in the first differential y'=f'(x) of the function y=f(x), a value T1 at x=X1 and a value T2 at x=X2 satisfy formula (1).

number

[0022] (Configuration 7) A seventh aspect is the mask blank of the sixth aspect, wherein X1 satisfies -a·W≦X1≦b1, and X2 satisfies b2≦X2≦a·W. W: Mark width D: Mark depth a: constant b1: When the coordinate in the depth direction of the surface of the mask blank on which the mark does not exist is y=0, the negative position in the width direction at y=-D / 3 b2: the positive position in the width direction when y=-D / 3

[0023] (Configuration 8) Configuration 8 is the mask blank of configuration 7, wherein the width W of the mark is 0.5 to 10 μm.

[0024] (Configuration 9) A 9th aspect is the mask blank of the 7th or 8th aspect, wherein the depth D of the mark is 10 to 80 nm.

[0025] (Configuration 10) A tenth aspect is the mask blank according to any one of the sixth to ninth aspects, wherein the thin film includes at least one selected from an absorber film, a light-shielding film, an etching mask film, and a resist film.

[0026] (Configuration 11) Configuration 11 is a transfer mask, characterized in that a pattern is formed on the thin film in the mask blank of configuration 6.

[0027] (Configuration 12) Configuration 12 includes preparing a mask blank according to any one of configurations 6 to 10; and patterning the thin film using the marks as references. Effect of the Invention

[0028] According to the present invention, it is possible to provide a mask blank and a transfer mask with higher detection accuracy of an electron beam lithography system. Also, according to the present invention, it is possible to provide a substrate with a multilayer reflective film for manufacturing a mask blank and a transfer mask with higher detection accuracy of an electron beam lithography system. [Brief description of the drawings]

[0029] [Figure 1] 1 is a cross-sectional view illustrating an example of a multilayer reflective film-coated substrate of the present embodiment. [Diagram 2] FIG. 2 is a cross-sectional schematic view showing another example of a multilayer reflective film-coated substrate of the present embodiment. [Diagram 3] 1A and 1B are a plan view schematic diagram of a multilayer reflective film coated substrate of the present embodiment and an enlarged view of a reference mark. [Figure 4] 4 is a cross-sectional schematic diagram of an example of a mark for illustrating the cross-sectional shape of the mark at a position corresponding to BB in FIG. 3 of the multilayer reflective film coated substrate of the present embodiment. FIG. [Diagram 5] FIG. 2 is a schematic cross-sectional view showing an example of a reflective mask blank of the present embodiment. [Figure 6] FIG. 2 is a schematic cross-sectional view showing another example of the reflective mask blank of the present embodiment. [Figure 7A-E] 5A to 5C are schematic cross-sectional views showing an example of a method for manufacturing the reflective mask of the present embodiment. [Figure 8] FIG. 2 is a schematic cross-sectional view showing an example of a transmission mask blank of the present embodiment. [Figure 9] FIG. 2 is a schematic cross-sectional view showing an example of a transmission mask according to the present embodiment. [Figure 10] FIG. 1 is a schematic diagram showing an example of an EUV exposure apparatus. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the following embodiments are merely for the purpose of specifically explaining the present invention, and are not intended to limit the scope of the present invention.

[0031] Fig. 1 shows a schematic cross-sectional view of an example of a multilayer reflective film-coated substrate 90 of this embodiment. Fig. 3 shows a schematic plan view of an example of a multilayer reflective film-coated substrate 90 of this embodiment. This embodiment is a multilayer reflective film-coated substrate 90 having a mark 20 with a predetermined cross-sectional shape. This embodiment is also a mask blank and a transfer mask having a mark 20 with a predetermined cross-sectional shape. The inventors found that the detection accuracy in an electron beam lithography apparatus differs depending on the shape of the edge of the mark 20, and arrived at the present invention.

[0032] In this specification, a "mask blank" refers to an original plate used to manufacture a transfer mask. The mask blank includes a reflective mask blank 100 and a transmissive mask blank 300 (see FIGS. 5, 6 and 8). The transmissive mask blank 300 may have a light-shielding film or a phase shift film as a light-shielding film 310 (see FIG. 8).

[0033] In this specification, the term "transfer mask" includes a reflective mask 200 and a transmissive mask 400 (see Figs. 7E and 9). The transmissive mask 400 has a transfer pattern (light-shielding film pattern 410) of the light-shielding film 310 (see Fig. 9). When the light-shielding film pattern 410 is a light-shielding film pattern, the mask is a binary type mask, and when the light-shielding film pattern 410 is a phase-shift film pattern, the mask is a phase-shift type mask.

[0034] In this specification, "thin film B is disposed (formed) on thin film A (or substrate)" means that thin film B is disposed (formed) in contact with the surface of thin film A (or substrate), and also includes the case where another thin film C is present between thin film A (or substrate) and thin film B. In addition, in this specification, for example, "thin film B is disposed in contact with the surface of thin film A (or substrate)" means that thin film A (or substrate) and thin film B are disposed so as to be in direct contact with each other, without another thin film being interposed between thin film A (or substrate) and thin film B. In addition, in this specification, "on" does not necessarily mean the upper side in the vertical direction. "On" merely indicates the relative positional relationship between the thin film, the substrate, etc.

[0035] The multilayer reflective film coated substrate 90, the mask blank, and the transfer mask of this embodiment will be described below.

[0036] <Substrate with multilayer reflective film 90> The multilayer reflective film coated substrate 90 of this embodiment will be described.

[0037] Fig. 1 is a cross-sectional schematic diagram showing an example of a multilayer reflective film-coated substrate 90 of the present embodiment. The multilayer reflective film-coated substrate 90 of the embodiment shown in Fig. 1 has a substrate 1 and a multilayer reflective film 2 disposed on the substrate 1, on one main surface of the substrate 1. As shown in Fig. 1, the multilayer reflective film-coated substrate 90 of the present embodiment can further include a back surface conductive film 5 on the other main surface of the substrate 1.

[0038] Fig. 2 is a cross-sectional schematic diagram showing another example of a multilayer reflective film-coated substrate 90 of this embodiment. The multilayer reflective film-coated substrate 90 shown in Fig. 1 includes, on one main surface of the substrate 1, a substrate 1, a multilayer reflective film 2 disposed on the substrate 1, and a protective film 3 disposed on the multilayer reflective film 2. As shown in Fig. 2, the multilayer reflective film-coated substrate 90 of this embodiment can further include a back surface conductive film 5 on the other main surface of the substrate 1.

[0039] The multilayer reflective film coated substrate 90 of this embodiment will be specifically described.

[0040] <<Substrate 1>> To prevent distortion of the transferred pattern due to heat during exposure to EUV light, the substrate 1 is preferably one having a low thermal expansion coefficient within the range of 0±5 ppb / ° C. Materials having a low thermal expansion coefficient within this range include, for example, SiO2-TiO2 glass, multi-component glass ceramics, etc.

[0041] The main surface (first main surface) of the substrate 1 on which a transfer pattern (absorber pattern 4a described later) is formed is preferably processed to increase its flatness. By increasing the flatness of the main surface of the substrate 1, the positional accuracy and transfer accuracy of the pattern can be increased. For example, in the case of EUV exposure, in a 132 mm×132 mm area of ​​the main surface of the substrate 1 on which a transfer pattern is formed, the flatness is preferably 0.1 μm or less, more preferably 0.05 μm or less, and particularly preferably 0.03 μm or less. In addition, the second main surface (rear surface) on the opposite side to the side on which the transfer pattern is formed is a surface fixed to the exposure device by an electrostatic chuck. In a 142 mm×142 mm area of ​​the rear surface, the flatness is 0.1 μm or less, more preferably 0.05 μm or less, and particularly preferably 0.03 μm or less. In this specification, the flatness is a value that indicates the warpage (deformation amount) of the surface indicated by TIR (Total Indicated Reading). The flatness (TIR) ​​is the absolute value of the difference in height between the highest point on the surface of substrate 1 above the focal plane, which is determined by the least squares method using the surface of substrate 1 as the reference plane, and the lowest point on the surface of substrate 1 below this focal plane.

[0042] In the case of EUV exposure, the surface roughness of the main surface of the substrate 1 on which the transfer pattern is formed is preferably 0.1 nm or less in terms of root mean square roughness (Rq). The surface roughness can be measured by an atomic force microscope.

[0043] The substrate 1 preferably has high rigidity to prevent deformation due to film stress of the thin films (such as the multilayer reflective film 2) formed thereon, and in particular, preferably has a high Young's modulus of 65 GPa or more.

[0044] <<Multilayer reflective film 2>>

[0045] The multilayer reflective film-coated substrate 90 of the embodiment includes a multilayer reflective film 2. The multilayer reflective film 2 provides a function of reflecting EUV light in the reflective mask 200. The multilayer reflective film 2 is a multilayer film in which layers containing elements with different refractive indices as main components are periodically laminated.

[0046] Generally, the multilayer reflective film 2 is a multilayer film in which thin films (high refractive index layers) of a light element or its compound, which is a high refractive index material, and thin films (low refractive index layers) of a heavy element or its compound, which is a low refractive index material, are alternately stacked in about 40 to 60 periods.

[0047] The multilayer film used as the multilayer reflective film 2 can be a structure in which a high refractive index layer / low refractive index layer stack structure in which a high refractive index layer and a low refractive index layer are stacked in this order from the substrate 1 side is stacked multiple times. The multilayer film can also be a structure in which a low refractive index layer / high refractive index layer stack structure in which a low refractive index layer and a high refractive index layer are stacked in this order from the substrate 1 side is stacked multiple times. Note that the top layer of the multilayer reflective film 2, that is, the surface layer of the multilayer reflective film 2 opposite to the substrate 1 side, is preferably a high refractive index layer. In the above-mentioned multilayer film, when a high refractive index layer / low refractive index layer stack structure in which a high refractive index layer and a low refractive index layer are stacked in this order from the substrate 1 side is stacked multiple times, the top layer is a low refractive index layer. In this case, if the low refractive index layer constitutes the top surface of the multilayer reflective film 2, it is easily oxidized, and the reflectance of the reflective mask 200 decreases. Therefore, it is preferable to form the multilayer reflective film 2 by further forming a high refractive index layer on the topmost low refractive index layer. On the other hand, in the above-mentioned multilayer film, when a low refractive index layer / high refractive index layer laminate structure in which a low refractive index layer and a high refractive index layer are laminated in this order from the substrate 1 side is one period, the uppermost layer becomes the high refractive index layer. Therefore, in this case, there is no need to form an additional high refractive index layer.

[0048] The high refractive index layer may be a layer containing silicon (Si). As the material containing Si, in addition to a simple substance of Si, a Si compound containing boron (B), carbon (C), nitrogen (N), oxygen (O) and / or hydrogen (H) in addition to Si may be used. By using a high refractive index layer containing Si, a reflective mask 200 having excellent reflectance to EUV light can be obtained. In addition, the low refractive index layer may be a simple substance of metal selected from molybdenum (Mo), ruthenium (Ru), rhodium (Rh) and platinum (Pt), or an alloy thereof. In addition, boron (B), carbon (C), nitrogen (N), oxygen (O) and / or hydrogen (H) may be added to these simple substances or alloys. In the multilayer reflective film-coated substrate 90 of this embodiment, it is preferable that the low refractive index layer is a molybdenum (Mo) layer and the high refractive index layer is a silicon (Si) layer. For example, as the multilayer reflective film 2 for reflecting EUV light having a wavelength of 13 nm to 14 nm (for example, a wavelength of 13.5 nm), a Mo / Si periodic laminate film in which Mo layers and Si layers are alternately laminated for about 40 to 60 periods can be preferably used. In addition, in the multilayer reflective film-coated substrate 90 of this embodiment, it is preferable that the low refractive index layer is a ruthenium (Ru) layer and the high refractive index layer is a silicon (Si) layer. For example, as the multilayer reflective film 2 for reflecting EUV light having a wavelength of 13 nm to 14 nm (for example, a wavelength of 13.5 nm), a Ru / Si periodic laminate film in which Ru layers and Si layers are alternately laminated for about 30 to 40 periods can be preferably used.

[0049] The reflectance of the multilayer reflective film 2 alone is usually 65% ​​or more, with the upper limit usually being 73%. The film thickness and period of each of the constituent layers of the multilayer reflective film 2 can be appropriately selected depending on the exposure wavelength. Specifically, the film thickness and period of each of the constituent layers of the multilayer reflective film 2 can be selected so as to satisfy the law of Bragg reflection. In the multilayer reflective film 2, there are multiple high refractive index layers and multiple low refractive index layers, but the film thicknesses of the high refractive index layers and the film thicknesses of the low refractive index layers do not necessarily have to be the same.

[0050] The method of forming the multilayer reflective film 2 is known in the art. The multilayer reflective film 2 can be formed by depositing each layer by, for example, ion beam sputtering. In the case of the Mo / Si periodic multilayer film described above, for example, a Si film having a thickness of about 4 nm is first deposited on the substrate 1 by using a Si target by ion beam sputtering or magnetron sputtering, and then a Mo film having a thickness of about 3 nm is deposited by using a Mo target. This constitutes one period, and 40 to 60 periods are stacked to form the multilayer reflective film 2 (the outermost layer is a Si film). Note that, although the number of steps increases in the case of 60 periods compared to 40 periods, the reflectance to EUV light can be increased.

[0051] <<Protective film 3>> The multilayer reflective film-coated substrate 90 of this embodiment preferably has a protective film 3 on the multilayer reflective film 2. The protective film 3 is disposed in contact with one of the surfaces of the multilayer reflective film 2 opposite to the substrate 1.

[0052] In the multilayer reflective film coated substrate 90 of this embodiment, by having the protective film 3 on the multilayer reflective film 2, it is possible to suppress damage to the surface of the multilayer reflective film 2 when manufacturing a reflective mask 200 (EUV mask) using the reflective mask blank 100. Therefore, the reflectance characteristic of the obtained reflective mask 200 to EUV light becomes good.

[0053] The protective film 3 preferably contains at least one selected from ruthenium (Ru), rhodium (Rh) and iridium (Ir). The protective film 3 more preferably contains at least one selected from ruthenium (Ru) and rhodium (Rh). The protective film 3 may further contain an additive element in addition to the above-mentioned elements. The additive element contained in the protective film 3 is preferably one or more elements selected from Tl, Hf, Ti, Zr, Mn, In, Ga, Cd, Bi, Ta, Pb, Ag, Al, V, Nb, Sn, Zn, Hg, Cr, Fe, Sb, W, Mo and Cu.

[0054] The content of Ru used in the protective film 3 is 50 atomic % or more and less than 100 atomic %, preferably 80 atomic % or more and less than 100 atomic %, and more preferably 95 atomic % or more and less than 100 atomic %. The content of Rh is 10 atomic % or more and less than 70 atomic %, preferably 20 atomic % or more and less than 60 atomic %, and more preferably 30 atomic % or more and less than 50 atomic %. In this case, the protective film 3 can have a sufficient reflectance of EUV light, while also having mask cleaning resistance, an etching stopper function when the absorber film 4 is etched, and a function of preventing deterioration of the multilayer reflective film 2 over time.

[0055] Moreover, the protective film 3 may have a laminated structure of two or more layers.

[0056] In the multilayer reflective film coated substrate 90 of this embodiment, an underlayer may be formed between the substrate 10 and the multilayer reflective film 2. The underlayer can be formed for the purposes of improving the smoothness of the main surface of the substrate 10, reducing defects, enhancing the reflectance of the multilayer reflective film 2, and correcting stress in the multilayer reflective film 2.

[0057] <<Backside conductive film 5>> The multilayer reflective film-coated substrate 90 of this embodiment may have a back surface conductive film 5 for electrostatic chuck. The back surface conductive film 5 may be formed on the second main surface (back surface) of the substrate 1 (opposite to the surface on which the multilayer reflective film 2 is formed, and on the intermediate layer if an intermediate layer such as a hydrogen penetration suppression film is formed on the substrate 1). The sheet resistance required for the back surface conductive film 5 for electrostatic chuck is usually 100Ω / □ (Ω / square) or less. The method for forming the back surface conductive film 5 is, for example, magnetron sputtering or ion beam sputtering using a target of a metal such as chromium or tantalum, or an alloy thereof. The chromium (Cr)-containing material of the back surface conductive film 5 is preferably a Cr compound containing at least one element selected from boron, nitrogen, oxygen, and carbon in Cr. Examples of Cr compounds include CrN, CrON, CrCN, CrCON, CrBN, CrBON, CrBCN, and CrBOCN. The tantalum (Ta)-containing material of the backside conductive film 5 is preferably Ta, an alloy containing Ta, or a Ta compound containing at least one of boron, nitrogen, oxygen, and carbon in any of these. Examples of Ta compounds include TaB, TaN, TaO, TaON, TaCON, TaBN, TaBO, TaBON, TaBCON, TaHf, TaHfO, TaHfN, TaHfON, TaHfCON, TaSi, TaSiO, TaSiN, TaSiON, and TaSiCON. The thickness of the backside conductive film 5 is not particularly limited as long as it satisfies the function for the electrostatic chuck, but is usually 10 nm to 200 nm.

[0058] The back surface conductive film 5 also functions to adjust the stress on the second main surface side of the reflective mask blank 100. That is, the back surface conductive film 5 is adjusted to achieve a balance with the stress from the various films formed on the first main surface side so as to obtain a flat reflective mask blank 100.

[0059] It is to be noted that the multilayer reflective film coated substrate 90 does not necessarily need to include the rear surface conductive film 5. For example, the rear surface conductive film 5 can be formed, if necessary, on a reflective mask blank 100 on which an absorber film 4 described below has been formed.

[0060] <<Mark 20>> The surface of the multilayer reflective film-coated substrate 90 of this embodiment has at least one concave mark 20 (see FIG. 3). The mark 20 is formed on the main surface of the multilayer reflective film-coated substrate 90 on which the multilayer reflective film 2 is disposed.

[0061] The "mark 20" used in this embodiment can also be formed on the reflective mask blank 100 and the reflective mask 200. The "mark 20" used in this embodiment can also be formed on the transmissive mask blank 300 and the transmissive mask 400. In the following explanation, the mark 20 formed on the multilayer reflective film-coated substrate 90 will be described as an example. In this specification, the mark 20 formed on the multilayer reflective film-coated substrate 90, mask blank, and transfer mask of this embodiment may be referred to as the "mark 20 used in this embodiment." The mark 20 used in this embodiment may also be simply referred to as the "mark 20."

[0062] The mark 20 used in this embodiment includes an AM (alignment mark) or an FM (fiducial mark) as a reference mark 20, and an ID mark as an identification symbol. In this specification, the "mark 20" refers to a minute concave or convex portion formed on the surface of a transfer mask used in photolithography. The mark 20 can be formed on a mask blank for manufacturing a transfer mask. The mark 20 on the mask blank can be formed by transferring the mark 20 formed on a multilayer reflective film-coated substrate 90. A transfer mask having a predetermined mark 20 can be obtained by manufacturing a transfer mask using a mask blank having the predetermined mark 20.

[0063] The mark 20 formed on the multilayer reflective film-coated substrate 90 of this embodiment can be a reference mark 20. The reference mark 20 can also be used as an AM (alignment mark). The AM is a mark that can be used as a reference for defect coordinates when defects on the multilayer reflective film 2 are inspected by a defect inspection device. Therefore, the AM needs to have a high contrast that can be detected by the defect inspection device. Examples of the defect inspection device include the "MAGICSM7360" mask substrate / blank defect inspection device for EUV exposure manufactured by Lasertec Corporation, which has an inspection light source wavelength of 266 nm, the "Teron600 series" EUV mask / blank defect inspection device manufactured by KLA-Tencor Corporation (e.g., "Teron610"), which has an inspection light source wavelength of 193 nm, and an ABI (Actinic Blank Inspection) device, which has an inspection light source wavelength of 13.5 nm, which is the same as the exposure light source wavelength. The AM is not directly used when drawing a pattern by an electron beam drawing device. The AM can be in a shape such as a circle, a rectangle, or a cross.

[0064] When an AM is formed on the multilayer reflective film 2, an FM can be formed on the absorber film 4 on the multilayer reflective film 2. The AM transferred to the absorber film 4 must be detectable by a defect inspection device and a coordinate measuring device. The FM must be detectable by a coordinate measuring device and an electron beam lithography device. By managing the coordinates relatively between the AM and the FM, the defect coordinates can be managed with high accuracy. It is also possible to remove a part of the absorber film 4 on the AM to expose the AM.

[0065] In the following description, an example will be given in which the mark 20 is used as a reference mark 20 of a multilayer reflective film-coated substrate 90. The reference mark 20 can be used as an FM (fiducial mark). In this case, the FM can also function as the AM described above. In addition, an example will be given in which the mark 20 is formed on the protective film 3 of the multilayer reflective film-coated substrate 90.

[0066] FIG. 3 is a plan view of a multilayer reflective film coated substrate 90 of this embodiment.

[0067] 3, fiducial marks 20 that can be used as references for defect positions in defect information are formed near the four corners of a substantially rectangular multilayer reflective film-coated substrate 90. Although an example in which four fiducial marks 20 are formed is shown, the number of fiducial marks 20 is not limited to four, and may be three or less, or five or more.

[0068] In the multilayer reflective film-coated substrate 90 shown in Fig. 3, the region inside the dashed line A (132 mm × 132 mm region) is a pattern formation region where the absorber pattern 4a (see Fig. 7E) is formed when the reflective mask 200 is manufactured. The region outside the dashed line A is a region where the absorber pattern 4a is not formed when the reflective mask 200 is manufactured. The reference mark 20 is preferably formed in the region where the absorber pattern 4a is not formed, i.e., the region outside the dashed line A.

[0069] As shown in Fig. 3, the reference mark 20 has, for example, a substantially cross shape. Fig. 4 is a cross-sectional view of the reference mark 20 shown in Fig. 3 taken along line BB, and shows a schematic diagram of the cross-sectional structure of the reference mark 20. When the reference mark 20 has a substantially cross shape, the length L shown in Fig. 3 is preferably 0.1 to 2 mm, and more preferably 0.5 to 1.5 mm. Moreover, the width W shown in Fig. 3 is the same as the width W of the mark 20, which will be described later.

[0070] 4, in the multilayer reflective film-coated substrate 90 of this embodiment, when a cross section of the multilayer reflective film-coated substrate 90 (a cross section perpendicular to the main surface of the multilayer reflective film-coated substrate 90) is viewed, the reference mark 20 is formed in a concave shape on the surface of the protective film 3. The term "concave shape" used here means that when the cross section of the multilayer reflective film-coated substrate 90 is viewed, the reference mark 20 is formed so as to be concave, for example, in a stepped or curved shape downward below the protective film 3.

[0071] Next, the shape of the mark 20 used in this embodiment will be described.

[0072] As shown in FIG. 4, in this specification, the shape (cross-sectional profile) of the mark 20 used in this embodiment can be expressed by a function y=f(x).

[0073] The cross-sectional profile of the mark 20 can be measured by a measuring method such as an atomic force microscope, a scanning electron microscope, or a transmission electron microscope. In the case of measurement by an atomic force microscope, the cross-sectional profile of the mark 20 formed on the surface of the multilayer reflective film-coated substrate 90 or the like can be measured as is. On the other hand, when measuring the cross-sectional profile of the mark 20 by a scanning electron microscope or a transmission electron microscope, pre-processing such as cutting out a cross section is required. Therefore, it is preferable to measure the cross-sectional profile of the mark 20 using an atomic force microscope.

[0074] In the following description, an example will be described in which the cross-sectional profile of the mark 20 is measured using an atomic force microscope. When the cross-sectional profile of the mark 20 is measured using another method, the cross-sectional profile expressed by the function y=f(x) can be obtained, as in the case of measurement using an atomic force microscope, and the following description can be applied.

[0075] As shown in FIG. 4, in this specification, in the cross-sectional profile of the mark 20 used in this embodiment, which is represented by a function y=f(x), the position in the width direction of the cross-sectional profile is x (μm), and the position in the depth direction perpendicular to the width direction is y (μm).

[0076] 4 is an explanatory diagram showing a schematic cross-sectional profile of the mark 20 used in the present embodiment, which is represented by a function y=f(x). As shown in FIG. 4, x is the position in the width direction of the mark 20 in the cross-sectional profile.

[0077] The origin of the position x in the width direction can be set to x = 0 μm, with the center point in the width direction of the cross-sectional profile of the mark 20 as the origin. The deepest point of the mark 20 in the cross-sectional profile of the mark 20 can be selected as the origin (x = 0 μm) of the width direction x of the cross-sectional profile of the mark 20. In addition, the center point of the half-width in the depth direction can be selected as the origin (x = 0 μm) of the width direction x of the cross-sectional profile of the mark 20. However, an arbitrary position can be set as the origin (x = 0 μm) of the width direction x, as necessary.

[0078] As shown in Fig. 4, y is the position in the depth direction perpendicular to the width direction. The origin of the position y in the depth direction can be set to y = 0 nm, with the surface of the multilayer reflective film-coated substrate 90 on which the mark 20 is not formed as the origin. Also, y = 0 nm can be set to the bottom of the mark 20 as the origin. However, if necessary, any position can be set to the origin of the depth direction y (y = 0 nm). Also, the depth direction can be set to the direction in which the value of y decreases.

[0079] 4, in this specification, the width of the mark 20 is defined as W (μm). The width W of the mark 20 can be measured as follows. That is, 20 pieces of cross-sectional profile data about 5 times the width of the mark 20 including the mark 20 at the approximate center are measured to obtain an average cross-sectional profile, and then an approximation line is obtained by approximating the cross section of the portion where the mark 20 is not formed with a straight line, and the width W of the mark 20 can be obtained by defining the end of the mark 20 as a point 1.0 nm deeper in the depth direction from the approximation line.

[0080] 4 is the depth of the mark 20. The depth D (nm) of the mark 20 can be calculated as the distance from a straight line (an approximation straight line of a portion where the mark 20 is not formed) approximated when the width W is calculated to a point at the bottom of the concave mark 20 that is the longest distance in the perpendicular direction to the straight line.

[0081] When the cross-sectional profile of the mark 20 is measured using an atomic force microscope, the conditions for measuring the cross-sectional profile using the atomic force microscope can be as follows: That is, for the portion of the surface on which the mark 20 is formed, the center of the mark 20 is set to x=0 μm, and a distance of 5 times the width W (a range of x=-2.5W to x=+2.5W) is scanned at 0.5 Hz. Data is collected every 20 nm (0.02 μm), and the function y=f(x) can be obtained as a curve showing a moving average of three points.

[0082] In addition, when measuring the cross-sectional profile of mark 20 using a method other than an atomic force microscope, the preparation of the measurement sample and the measurement conditions can be selected so that the measurement results are similar to those obtained by an atomic force microscope.

[0083] In this manner, the function y=f(x), which is the cross-sectional profile of the mark 20 used in this embodiment, can be obtained.

[0084] Next, the first differential y'=f'(x) and the second differential y''=f''(x) of the function y=f(x), which is the cross-sectional profile of the mark 20 used in this embodiment, are calculated.

[0085] Next, based on the second derivative y''=f''(x) of the function y=f(x), x is obtained where x=X1 and x=X2. X1 is one position x in the width direction where the value of the second derivative y''=f''(x) of the function y=f(x) is the minimum value. X2 is the other position x in the width direction where the value of the second derivative y''=f''(x) is the minimum value. When the center in the width direction is x=0 μm, X1 and X2 exist at one position in the negative x region and one position in the positive x region. Among the positions x where the value of the second derivative y''=f''(x) is the minimum value, the minimum value in the negative x region can be designated as X1 and the minimum value in the positive x region can be designated as X2. Figure 4 shows the positions where x=X1 and x=X2.

[0086] Next, for the first derivative y'=f'(x) of the function y=f(x), calculate the value T1 (=f'(X1)) at x=X1. Similarly, for the first derivative y'=f'(x) of the function y=f(x), calculate the value T2 (=f'(X2)) at x=X2.

[0087] In the multilayer reflective film coated substrate 90 of this embodiment, T1 and T2 determined as described above satisfy the following formula (1). n is T1 or T2.

number

[0088] The values ​​T1 and T2 obtained as described above correspond to the slope of the function y=f(x) at the x positions (X1 and X2) where the rate of change of the slope of the function y=f(x) (cross-sectional profile of the mark 20) ​​is the largest. The inventors discovered that the detection accuracy of the mark 20 by the electron beam lithography device is improved by setting the slopes T1 and T2 of the function y=f(x) at the predetermined positions X1 and X2 within a predetermined range, and arrived at the present invention. The slopes T1 and T2 are preferably 0.05 or more, more preferably 0.08 or more, and even more preferably 0.10 or more. Moreover, the slopes T1 and T2 are preferably 0.20 or less, more preferably 0.18 or less, and even more preferably 0.16 or less.

[0089] The predetermined positions X1 and X2 are located near the edge of the mark 20. This is because the change in the inclination near the center (bottom) of the mark 20 is gradual in the cross section of the mark 20. The mark 20 used in this embodiment, which satisfies the above formula (1), means that there is a sudden change in the inclination of the function y=f(x), which is the cross-sectional profile, near the edge of the mark 20. The inventors have found that in order to improve the detection accuracy of the mark 20 by an electron beam lithography device, there must be a sudden change in the inclination near the edge of the mark 20, and have arrived at the present invention. That is, it can be said that the mark 20 of the multilayer reflective film-coated substrate 90 of this embodiment has a unique shape of the edge of the mark 20 that has never been seen before.

[0090] As described above, in order to find the slopes T1 and T2 of the function y=f(x), x that becomes X1 and X2 is found from the minimum value of the second derivative y″ based on the second derivative y″=f″(x) of the function y=f(x). X1 and X2 can be found as follows. That is, in the multilayer reflective film coated substrate 90 of this embodiment, X1 is, -a·W≦X1≦b1···Formula (2) and X2 is b2≦X2≦a·W Formula (3) The meanings of W, D, a, b1, and b2 are as follows. The origin (x=0) of the width direction x can be set to the center position of the mark 20 in the width direction, or the deepest position of the mark 20. W: Width of Mark 20 D: Depth of Mark 20 a: constant b1: When the coordinate in the depth direction of the surface of the multilayer reflective film-coated substrate 90 where the mark 20 does not exist is y=0, the negative position in the width direction x at which y=-D / 3 occurs b2: The positive position in the width direction x when y = -D / 3

[0091] In Figure 4, the range of formula (2) is shown as "Range 1" and the range of formula (3) is shown as "Range 2." X1 and X2 can be selected as the x that is the minimum value of the second derivative y''=f''(x) in the range of formula (2) and the range of formula (3), respectively.

[0092] The constant a is preferably a constant in the range of 0.7 to 1.0, and more preferably 0.75. The constant a is a constant for taking into consideration a range up to a times the width W of the mark 20 in the width direction (x direction) of the cross section of the mark 20 when calculating X1 and X2.

[0093] During processing to form the mark 20 on the multilayer reflective film-coated substrate 90 of this embodiment, the surface roughness of the bottom of the mark 20 may increase, resulting in the presence of uneven shapes of unexpected size. As shown in FIG. 4, when X1 satisfies -a·W≦X1≦b1 and X2 satisfies b2≦X2≦a·W, the bottom of the mark 20 deeper than -D / 3 can be excluded from the range when calculating X1 and X2. Therefore, in the multilayer reflective film-coated substrate 90 of this embodiment, when calculating the slopes T1 and T2 of the function y=f(x), X1 satisfies -a·W≦X1≦b1 and X2 satisfies b2≦X2≦a·W, X1 and X2 near the edge of the mark 20 can be appropriately selected even if the bottom of the mark 20 has uneven shapes of unexpected size.

[0094] In the multilayer reflective film coated substrate 90 of this embodiment, the width W of the mark 20 is preferably 0.5 μm or more, and more preferably 1 μm or more. The width W of the mark 20 is preferably 10 μm or less, more preferably 5 μm or less, and even more preferably 3 μm. When the width W of the mark 20 is within a predetermined range, the detection accuracy of the mark 20 by the electron beam lithography device can be improved.

[0095] In the multilayer reflective film coated substrate 90 of this embodiment, the depth D of the mark 20 is preferably 10 to 80 nm (0.01 to 0.08 μm), and more preferably 30 to 80 nm (0.03 to 0.08 μm). When the depth D of the mark 20 is within a predetermined range, the detection accuracy of the mark 20 by the electron beam lithography apparatus can be improved.

[0096] The ratio D / W of the depth D to the width W of the mark 20 is preferably 0.001 to 0.16, more preferably 0.002 to 0.16, and even more preferably 0.01 to 0.08. When the ratio D / W of the depth D to the width W of the mark 20 is within a predetermined range, the detection accuracy of the mark 20 by the electron beam drawing apparatus can be improved.

[0097] The method of forming the mark 20 is not particularly limited. The mark 20 can be formed on the surface of the protective film 3 by, for example, laser processing, focused ion beam (FIB), photolithography, processing marks by scanning a diamond needle, imprinting, or the like. The mark 20 is preferably formed by laser processing or focused ion beam. When the mark 20 is formed by focused ion beam, the mark 20 having a predetermined cross-sectional profile can be formed by changing the beam current of the FIB. When the mark 20 is formed by laser processing, the type of laser is a laser with a wavelength in the ultraviolet to visible light range, and for example, a semiconductor laser with a wavelength of 405 nm can be used. The mark 20 having a predetermined cross-sectional profile can be formed by changing the output, scanning speed, frequency, and / or focus of the laser.

[0098] The laser used for laser processing the mark 20 may be a continuous wave or a pulse wave. When a pulse wave is used, it is possible to make the width W of the mark 20 smaller than when a continuous wave is used, even if the depth D of the mark 20 is the same. Furthermore, when a pulse wave is used, it is possible to control the shape of the edge of the mark 20, for example by increasing the inclination angle of the edge of the mark 20, compared to when a continuous wave is used. Therefore, when a pulse wave is used, it is possible to form a mark 20 having a predetermined cross-sectional profile that has a higher contrast and is easier to detect by a defect inspection device or an electron beam drawing device, compared to when a continuous wave is used.

[0099] The shape of the mark 20 is preferably a point-symmetric shape. It is not limited to the cross shape shown in FIG. 4, but may be, for example, a square shape, a square shape with rounded corners, an octagonal shape, or a perfect circle shape. The shape of the mark 20 may be a substantially L-shape in plan view. The width W of the mark 20 of any shape may be the width W between any two points on the edge of the mark 20 that are arranged with a concave portion between them when the mark 20 is viewed in plan view. The cross-sectional profile between the two points having the width W may be the above-mentioned function y=f(x).

[0100] Furthermore, the mark 20 may have a double shape with a groove at approximately the center. For example, in the case of a cross shape, a cross-shaped groove similar or approximately similar to the cross shape may be further provided at the center of the cross-shaped groove. The same applies to marks 20 of other shapes. Note that "similar or approximately similar" includes not only shapes that are geometrically similar, but also shapes that are similar overall even if they are not strictly geometrically similar.

[0101] The above description has been given taking as an example a case where the mark 20 is formed on the protective film 3 of the multilayer reflective film coated substrate 90, but the above description is also applicable to a case where the mark 20 is formed on the multilayer reflective film 2.

[0102] <Mask blank> Next, the mask blank of the present embodiment will be described. The mask blank of the present embodiment includes a reflective mask blank 100 and a transmissive mask blank 300.

[0103] This embodiment is a mask blank having a substrate 1 and a thin film for pattern formation disposed on the substrate 1. The surface of the mask blank of this embodiment has at least one concave mark 20. As explained above about the multilayer reflective film-coated substrate 90 of this embodiment, the mark 20 of the mask blank of this embodiment has a predetermined cross-sectional profile. When the cross-sectional profile of the mark 20 is expressed by a function y=f(x), the value T1 at x=X1 and the value T2 at x=X2 in the first differential y'=f'(x) of the function y=f(x) satisfy the formula (1). Note that X1 is one position x in the width direction at which the value of the second differential y''=f''(x) of the function y=f(x) is the minimum value. X2 is the other position x in the width direction at which the value of the second differential y''=f''(x) is the minimum value. T n is T1 or T2.

number

[0104] In the mask blank of this embodiment, the slopes T1 and T2 of the function y=f(x) of the cross-sectional profile of the mark 20 at the specified positions X1 and X2 are within the specified ranges as described above, thereby improving the detection accuracy of the mark 20 by the electron beam lithography apparatus.

[0105] In the mask blank of this embodiment, the thin film for pattern formation preferably includes at least one selected from the absorber film 4, the light-shielding film 310, the etching mask film 6, and the resist film 11. When the thin film of the mask blank of this embodiment includes a predetermined thin film, a transfer mask can be manufactured using the mask blank.

[0106] As described above, the mark 20 formed on the multilayer reflective film 2 of the multilayer reflective film-coated substrate 90 is also transferred to a thin film for pattern formation (at least one selected from the absorber film 4, the light-shielding film 310, the etching mask film 6, and the resist film 11) when a thin film for pattern formation is formed on the multilayer reflective film-coated substrate 90. Therefore, "the surface of the mask blank has at least one concave mark 20" includes not only the case where the mark 20 is formed in the thin film for pattern formation on the surface of the mask blank, but also the case where the mark 20 formed in the thin film (or the substrate 1) below the thin film for pattern formation is transferred to the thin film for pattern formation.

[0107] The reflective mask blank 100 and the transmissive mask blank 300 of this embodiment will be described.

[0108] <<Reflective mask blank 100>> 5 and 6 are schematic diagrams showing a cross section of a reflective mask blank 100 of this embodiment. The reflective mask blank 100 of this embodiment can be manufactured by forming an absorber film 4 that absorbs EUV light on the multilayer reflective film 2 of the multilayer reflective film-coated substrate 90 described above or on the protective film 3.

[0109] The reflective mask blank 100 of this embodiment has a mark 20 similar to the mark 20 of the multilayer reflective film-coated substrate 90. The mark 20 of the reflective mask blank 100 of this embodiment can be formed by transferring the mark 20 formed on the multilayer reflective film-coated substrate 90 to the absorber film 4. By forming the absorber film 4 on the surface of the multilayer reflective film-coated substrate 90 having the mark 20, the mark 20 formed on the multilayer reflective film-coated substrate 90 can be transferred to the absorber film 4. Moreover, the mark 20 of the reflective mask blank 100 of this embodiment can be formed by a method similar to the method of forming the mark 20 on the multilayer reflective film-coated substrate 90 described above, after forming the absorber film 4 on the multilayer reflective film-coated substrate 90 on which the mark 20 is not formed.

[0110] The absorber film 4 has a function of absorbing EUV light, which is the exposure light. That is, the difference between the reflectance of the multilayer reflective film 2 for EUV light and the reflectance of the absorber film 4 for EUV light is a predetermined value or more. For example, the reflectance of the absorber film 4 for EUV light is 0.1% or more and 40% or less. There may be a predetermined phase difference between the light reflected by the multilayer reflective film 2 and the light reflected by the absorber film 4. In this case, the absorber film 4 in the reflective mask blank 100 may be called a phase shift film.

[0111] The absorber film 4 preferably has a function of absorbing EUV light and is removable by etching or the like. The absorber film 4 is preferably etchable by dry etching using a chlorine (Cl)-based gas or a fluorine (F)-based gas. As long as the absorber film 4 has such a function, the material of the absorber film 4 is not particularly limited.

[0112] The absorber film 4 may be a single layer or may have a laminated structure. When the absorber film 4 has a laminated structure, a plurality of films made of the same material may be laminated, or a plurality of films made of different materials may be laminated. When the absorber film 4 has a laminated structure, the material or composition may change stepwise and / or continuously in the thickness direction of the film.

[0113] The material of the absorber film 4 is not particularly limited as long as it has the function of absorbing EUV light, can be processed by etching or the like (preferably can be etched by dry etching with a chlorine (Cl)-based gas and / or a fluorine (F)-based gas), and has a high etching selectivity relative to the protective film 3. As a material having such a function, at least one metal selected from palladium (Pd), silver (Ag), platinum (Pt), gold (Au), iridium (Ir), tungsten (W), chromium (Cr), cobalt (Co), manganese (Mn), tin (Sn), tantalum (Ta), vanadium (V), nickel (Ni), hafnium (Hf), iron (Fe), copper (Cu), tellurium (Te), zinc (Zn), magnesium (Mg), germanium (Ge), aluminum (Al), rhodium (Rh), ruthenium (Ru), molybdenum (Mo), niobium (Nb), titanium (Ti), zirconium (Zr), yttrium (Y), and silicon (Si), an alloy containing two or more metals, or a compound thereof can be preferably used. The compound may contain oxygen (O), nitrogen (N), carbon (C) and / or boron (B) in said metal or alloy.

[0114] The thickness of the absorber film 4 is preferably 30 nm to 100 nm.

[0115] The absorber film 4 can be formed by a known method, such as magnetron sputtering or ion beam sputtering.

[0116] In the reflective mask blank 100 of this embodiment, a resist film 11 may be formed on the absorber film 4. This embodiment is shown in Fig. 7A. A pattern is written and exposed on the resist film 11 by an electron beam lithography device, and then a development process is performed to form a resist pattern 11a. A pattern (absorber pattern 4a) can be formed in the absorber film 4 by dry etching the absorber film 4 using this resist pattern 11a as a mask.

[0117] As shown in FIG. 6, the reflective mask blank 100 of this embodiment can have an etching mask film 6. When the reflective mask blank 100 of this embodiment has a resist film 11, the etching mask film 6 can be disposed between the absorber film 4 and the resist film 11. The etching mask film 6 is used as a mask when patterning the absorber film 4. The etching mask film 6 is formed of a material having etching selectivity with respect to the absorber film 4. The material of the etching mask film 6 preferably contains a chromium compound, a tantalum compound, or a silicon compound. The chromium compound contains Cr and at least one selected from the group consisting of N, O, C, and H. The tantalum compound contains Ta and at least one selected from the group consisting of N, O, B, and H. The silicon compound contains Si and at least one selected from the group consisting of N, O, C, and H.

[0118] The reference mark 20 transferred to the absorber film 4, the etching mask film 6, and the resist film 11 must have a high enough contrast to be detectable by an electron beam lithography device. The resist film 11 above the reference mark 20 may be locally removed so that the concave reference mark 20 transferred to the surface of the reflective mask blank 100 can be easily detected by an electron beam lithography device. The manner of removal is not particularly limited. Also, for example, the absorber film 4, the etching mask film 6, and the resist film 11 above the reference mark 20 may be removed.

[0119] <<Transmissive Mask Blank 300>> This embodiment can also be applied when forming a reference mark 20 on a transmission mask blank 300 in which a light-shielding film 310 is disposed on a substrate 1.

[0120] Next, the transmission mask blank 300 of this embodiment will be described below. Fig. 8 shows a schematic cross-sectional view of an example of the transmission mask blank 300 of this embodiment. The transmission mask blank 300 of this embodiment has a substrate 1 and a light-shielding film 310. The substrate 1 can be a glass substrate.

[0121] The transmissive mask blank 300 of this embodiment has a mark 20 similar to the mark 20 of the reflective mask blank 100 described above. That is, the transmissive mask blank 300 of this embodiment has a mark 20 similar to the mark 20 of the multilayer reflective film-coated substrate 90 and the reflective mask blank 100 described above. The mark 20 of the transmissive mask blank 300 of this embodiment can be formed by transferring the mark 20 formed on the substrate 1 to the light-shielding film 310. Moreover, the mark 20 of the transmissive mask blank 300 of this embodiment can be formed by a method similar to the method for forming the mark 20 of the reflective mask blank 100 described above, after forming the light-shielding film 310 on the substrate 1 on which the mark 20 is not formed.

[0122] The transmission mask blank 300 of this embodiment has a configuration in which a light-shielding film 310 that will become the light-shielding film pattern 410 is formed on the main surface of the substrate 1 on the side on which the light-shielding film pattern 410 is to be formed.

[0123] The transmission type mask blank 300 may be, for example, a binary type mask blank or a phase shift type mask blank. The light-shielding film 310 may include a light-shielding film having a function of blocking exposure light. Alternatively, the light-shielding film 310 may include a halftone film (phase shift film) that attenuates the exposure light and shifts the phase of the exposure light.

[0124] The binary type transmission mask blank 300 has a light-shielding film for blocking exposure light formed on a substrate 1. This light-shielding film can be patterned to form a desired light-shielding film pattern. Examples of the light-shielding film include a Cr film, a Cr alloy film selectively containing oxygen, nitrogen, carbon, and fluorine in Cr, a laminated film thereof, a MoSi film, a MoSi alloy film selectively containing oxygen, nitrogen, and carbon in MoSi, and a laminated film thereof. An anti-reflection layer having an anti-reflection function may be formed on the surface of the light-shielding film.

[0125] The phase-shift type transmission mask blank 300 is formed by forming a phase shift film that changes the phase of exposure light on the substrate 1. This phase shift film can be patterned to form a desired transfer pattern. An example of the phase shift film can be a SiO2 film having a phase shift function. In addition, an example of the phase shift film can be a halftone film such as a metal silicide oxide film, a metal silicide nitride film, a metal silicide oxynitride film, a metal silicide oxycarbide film, a metal silicide oxynitride carbide film (metal is a transition metal such as Mo, Ti, W, Ta), a CrO film, a CrF film, and a SiON film, each having a phase shift function and a light-shielding function. The light-shielding film may be formed on the phase shift film.

[0126] The transmission mask blank 300 of this embodiment is not limited to the configuration shown in Fig. 8. For example, a resist film serving as a mask for patterning the light-shielding film 310 may be formed on the light-shielding film 310.

[0127] The resist film formed on the light-shielding film 310 may be either positive type or negative type. In addition, the resist film formed on the light-shielding film 310 may be for electron beam drawing or for laser drawing. Furthermore, a hard mask (etching mask) film may be formed between the light-shielding film 310 and the resist film.

[0128] <Transfer mask> Next, the transfer mask of this embodiment will be described. The transfer mask of this embodiment includes a reflective mask 200 and a transmissive mask 400.

[0129] This embodiment is a transfer mask having a substrate 1 and a thin film disposed on the substrate 1 and having a pattern formed thereon. The surface of the transfer mask of this embodiment has at least one concave mark 20. As in the above description of the multilayer reflective film-coated substrate 90 of this embodiment, the mark 20 of the transfer mask of this embodiment has a predetermined cross-sectional profile. When the cross-sectional profile of the mark 20 is expressed by a function y=f(x), the value T1 at x=X1 and the value T2 at x=X2 in the first differential y'=f'(x) of the function y=f(x) satisfy the formula (1). Note that X1 is one position x in the width direction at which the value of the second differential y''=f''(x) of the function y=f(x) is the minimum value. X2 is the other position x in the width direction at which the value of the second differential y''=f''(x) is the minimum value. T n is T1 or T2.

number

[0130] The mask blank of the transfer mask of this embodiment has a mark 20 with a predetermined cross-sectional profile. In the function y=f(x) of the cross-sectional profile of the predetermined mark 20, the slopes T1 and T2 of the function y=f(x) at the predetermined positions X1 and X2 are within the same predetermined range as described above, so that the detection accuracy of the mark 20 by the electron beam lithography device is higher. By manufacturing the transfer mask using the predetermined mark 20 as a reference, the detection accuracy of the mark 20 by the electron beam lithography device is higher when manufacturing the transfer mask. Therefore, according to this embodiment, a transfer mask with higher accuracy can be obtained.

[0131] The thin film of the transfer mask of this embodiment preferably includes at least one selected from absorber film 4 and light-shielding film 310. By including a predetermined thin film, the thin film of the transfer mask of this embodiment can be used as a transfer mask for photolithography in the manufacturing process of a semiconductor device.

[0132] This embodiment is a method for manufacturing a transfer mask. The method for manufacturing a transfer mask of this embodiment includes preparing the above-mentioned mask blank and patterning a thin film using the mark 20 as a reference. By manufacturing a transfer mask using a predetermined mark 20 as a reference, the detection accuracy of the mark 20 by an electron beam lithography device is higher when manufacturing the transfer mask. Therefore, a transfer mask with higher accuracy can be manufactured by the method for manufacturing a transfer mask of this embodiment.

[0133] The reflective mask 200 and the transmissive mask 400 of this embodiment will be described.

[0134] <<Reflection mask 200>> The reflective mask blank 100 of this embodiment can be used to manufacture the reflective mask 200 of this embodiment. The reflective mask 200 of this embodiment is a type of transfer mask. A method for manufacturing the reflective mask 200 will be described below.

[0135] 7A to 7E are schematic diagrams showing a method for manufacturing a reflective mask 200. Note that in Fig. 7A to 7E, the marks 20 are omitted from the illustration.

[0136] First, a reflective mask blank 100 is prepared, which has a substrate 1, a multilayer reflective film 2 formed on the substrate 1, a protective film 3 formed on the multilayer reflective film 2, an absorber film 4 formed on the protective film 3, and an etching mask film 6 formed on the absorber film 4. Next, as shown in Fig. 7A, a resist film 11 is formed on the etching mask film 6. A pattern is written on the resist film 11 by an electron beam lithography device, and a developing and rinsing process is further performed to form a resist pattern 11a (Fig. 7B).

[0137] When a pattern is written by the electron beam lithography system, the coordinates of the mark 20 (reference mark 20) ​​on the etching mask film 6 measured by a coordinate measuring device can be used as a reference. By using the mark 20 (reference mark 20) ​​as an FM (fiducial mark) that is a reference for the defect position, the coordinate system of the defect inspection device can be converted to the coordinate system of the coordinate measuring device. Then, the above-mentioned mark 20 (reference mark 20) ​​is detected by the electron beam lithography system. A single beam or multiple beams can be used to detect the mark 20 (reference mark 20) ​​by the electron beam lithography system. In particular, when multiple beams are used, the accuracy of mark detection is low, so that the mark 20 can be detected with high accuracy by having the above-mentioned predetermined cross-sectional profile. Since the position of the defect can be specified by using the FM as a reference, the position of the resist pattern 11a can be adjusted so that the defect does not adversely affect the reflective mask 200.

[0138] Using the resist pattern 11a as a mask, the etching mask film 6 is dry-etched, whereby the portions of the etching mask film 6 that are not covered by the resist pattern 11a are etched, and an etching mask pattern 6a is formed (FIG. 7C).

[0139] Using the etching mask pattern 6a as a mask, the absorber film 4 is dry-etched. As a result, the portion of the absorber film 4 that is not covered by the etching mask pattern 6a is etched, and the absorber pattern 4a is formed (FIG. 7D).

[0140] Examples of the etching gas that can be used include chlorine-based gases such as Cl2, SiCl4, CHCl3, and CCl4, mixed gases containing these chlorine-based gases and O2 in a predetermined ratio, mixed gases containing chlorine-based gases and He in a predetermined ratio, mixed gases containing chlorine-based gases and Ar in a predetermined ratio, fluorine-based gases such as CF4, CHF3, C2F6, C3F6, C4F6, C4F8, CH2F2, CH3F, C3F8, SF6, and F, mixed gases containing these fluorine-based gases and O2 in a predetermined ratio, mixed gases containing fluorine-based gas and He in a predetermined ratio, and mixed gases containing fluorine-based gas and Ar in a predetermined ratio.

[0141] After the absorber pattern 4a is formed, the etching mask pattern 6a is removed by dry etching. After removing the etching mask pattern 6a, a wet cleaning process is performed using an acidic or alkaline aqueous solution, thereby obtaining the reflective mask 200 of this embodiment (FIG. 7E).

[0142] <<Transmissive mask 400>> Next, a description will be given of the transmission mask 400 of this embodiment. The transmission mask 400 of this embodiment is a type of transfer mask. The transmission mask 400 of this embodiment has marks 20 similar to the marks 20 of the reflective mask 200 described above.

[0143] FIG. 9 is a schematic diagram showing a transmission mask 400 of the present embodiment.

[0144] The transmission mask 400 of this embodiment has a light-shielding film pattern 410 obtained by patterning the light-shielding film 310 of the above-mentioned transmission mask blank 300. The transmission mask 400 of this embodiment may be a binary type mask or a phase shift type mask.

[0145] <Method of Manufacturing Semiconductor Device> The method for manufacturing the semiconductor device of this embodiment will be described by taking as an example the case where the reflective mask 200 of this embodiment is used.

[0146] The method for manufacturing a semiconductor device according to this embodiment includes a step of performing a lithography process using the above-described reflective mask 200 and an EUV exposure tool 50 to form a transfer pattern on a transfer target object. Fig. 10 is a schematic diagram showing an example of the EUV exposure tool 50.

[0147] A transfer pattern can be formed on a semiconductor substrate 60 (transfer target) by lithography using the reflective mask 200 of this embodiment. This transfer pattern has a shape transferred from the pattern of the reflective mask 200. By forming a transfer pattern on the semiconductor substrate 60 by the reflective mask 200, a semiconductor device can be manufactured.

[0148] According to this embodiment, when the etching mask pattern 6a is removed by etching in manufacturing the reflective mask 200, damage to the multilayer reflective film 2 and / or the protective film 3 can be reduced, so that the reflective mask 200 having high reflectance to EUV light can be obtained. Therefore, by using the reflective mask 200 of this embodiment, it is possible to increase the density and accuracy of a semiconductor device.

[0149] A method of transferring a pattern to a semiconductor substrate 60 with a resist by using EUV light will be described with reference to FIG.

[0150] 10 shows a schematic configuration of an EUV exposure tool 50 which is a tool for transferring a transfer pattern onto a resist film formed on a semiconductor substrate 60. In the EUV exposure tool 50, an EUV light generation unit 51, an irradiation optical system 56, a reticle stage 58, a projection optical system 57, and a wafer stage 59 are precisely arranged along the optical path axis of the EUV light. The container of the EUV exposure tool 50 is filled with hydrogen gas.

[0151] The EUV light generation unit 51 has a laser light source 52, a tin droplet generation unit 53, a capture unit 54, and a collector 55. When the high-power carbon dioxide laser from the laser light source 52 is irradiated onto the tin droplets released from the tin droplet generation unit 53, the tin in the droplet state is converted into plasma and EUV light is generated. The generated EUV light is collected by the collector 55 and passes through the irradiation optical system 56 to be incident on the reflective mask 200 set on the reticle stage 58. The EUV light generation unit 51 generates EUV light with a wavelength of, for example, 13.53 nm.

[0152] The EUV light reflected by the reflective mask 200 is reduced by the projection optical system 57 to a pattern image light, usually about 1 / 4, and projected onto the semiconductor substrate 60 (transferred substrate). As a result, a given circuit pattern is transferred to the resist film on the semiconductor substrate 60. A resist pattern can be formed on the semiconductor substrate 60 by developing the exposed resist film. An integrated circuit pattern can be formed on the semiconductor substrate 60 by etching the semiconductor substrate 60 using the resist pattern as a mask. A semiconductor device is manufactured through these steps and other necessary steps.

[0153] Furthermore, a semiconductor device can be manufactured by a lithography process using the above-mentioned transmission mask 400 and an exposure device. Specifically, the light-shielding film pattern 410 of the transmission mask 400 is transferred to a resist film formed on a semiconductor substrate. After that, a semiconductor device having a pattern (circuit pattern, etc.) formed on the semiconductor substrate can be manufactured by going through necessary processes such as a development process and a cleaning process.

[0154] In the method for manufacturing a semiconductor device of this embodiment, the transfer mask of this embodiment is used. The transfer mask of this embodiment is a transfer mask with higher detection accuracy of the electron beam lithography device, and therefore defect coordinates can be managed with high accuracy. Therefore, the reflective mask 200 of this embodiment is less affected by defects and is a high-performance reflective mask 200. Therefore, by using the transfer mask of this embodiment, a semiconductor device with higher performance can be manufactured. EXAMPLES

[0155] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these.

[0156] As examples and comparative examples, a multilayer reflective film-coated substrate 90 was produced in which a multilayer reflective film 2 and a protective film 3 were formed on a first main surface of a substrate 1. A mark 20 (reference mark 20) ​​was formed on the multilayer reflective film-coated substrate 90 of the examples and comparative examples under the conditions shown in Tables 1 and 2.

[0157] The multilayer reflective film coated substrates 90 of the examples and comparative examples were produced as follows.

[0158] A SiO2-TiO2-based glass substrate 1, which is a low-thermal expansion glass substrate 1 having a size of 6025 (approximately 152 mm × 152 mm × 6.35 mm) with both the first and second main surfaces polished, was prepared as the substrate 1. In order to obtain a flat and smooth main surface, polishing was performed by a rough polishing process, a precision polishing process, a localized polishing process, and a touch polishing process.

[0159] A back surface conductive film 5 made of a CrN film was formed by magnetron sputtering (reactive sputtering) on ​​the second main surface (back surface) of the SiO2-TiO2-based glass substrate 1. The back surface conductive film 5 was formed to a thickness of 70 nm using a TaB target in an argon (Ar) gas atmosphere.

[0160] Next, a multilayer reflective film 2 was formed on the main surface (first main surface) of the substrate 1 opposite to the side on which the back conductive film 5 was formed. The multilayer reflective film 2 formed on the substrate 1 was a periodic multilayer reflective film made of molybdenum (Mo) and silicon (Si) in order to make the multilayer reflective film 2 suitable for EUV light with a wavelength of 13.5 nm. The multilayer reflective film 2 was formed by alternately laminating Mo layers and Si layers on the substrate 1 by ion beam sputtering in a krypton (Kr) gas atmosphere using a Mo target and a Si target. First, a Si film was formed with a thickness of 4.2 nm, and then a Mo film was formed with a thickness of 2.8 nm. This constitutes one period, and 40 periods were laminated in the same manner, and finally a Si film was formed with a thickness of 4.0 nm to form the multilayer reflective film 2.

[0161] Next, a protective film 3 containing a Ru compound was formed on the multilayer reflective film 2. Specifically, a RuNb target (Ru: 80 atomic %, Nb: 20 atomic %) was used to form the protective film 3 made of a RuNb film on the multilayer reflective film 2 by DC magnetron sputtering in an Ar gas atmosphere. The thickness of the protective film 3 was 2.5 nm.

[0162] As described above, the multilayer reflective film coated substrates 90 of the example and the comparative example were produced.

[0163] Next, a reference mark 20 was formed as the mark 20 on the protective film 3 of the multilayer reflective film coated substrate 90 of each of the example and the comparative example.

[0164] A reference mark 20 was formed by laser processing on the protective film 3 of the multilayer reflective film-coated substrate 90 of each of Examples 1 to 4, 6, and 7 and Comparative Examples 1 and 2. The processing conditions were as shown in Tables 1 and 2, and the laser processing conditions shown below. Laser type: Semiconductor laser with wavelength of 405 nm Laser output: 30mW~80mW (pulse wave) Frequency: 50~500kHz Spot size: 430nmφ

[0165] The shape of the reference mark 20 in Examples 1 to 4, 6, and 7 and Comparative Examples 1 and 2 was a cross shape as shown in Fig. 3, and the length L was 1 mm. The depth D and width W of the reference mark 20 in Examples 1 to 4, 6, and 7 and Comparative Examples 1 and 2 were as shown in Tables 1 and 2.

[0166] A reference mark 20 was formed as the mark 20 on the protective film 3 of the multilayer reflective film coated substrate 90 of Example 5 and Comparative Example 3 by using a focused ion beam (FIB). The processing conditions were as follows. Ion type: Gallium ion Acceleration voltage: 30 kV Beam current: 60pA~500pA

[0167] The shape of the reference mark 20 in Example 5 and Comparative Example 3 was a cross shape as shown in Fig. 3, and the length L was 1 mm. The depth D and width W of the reference mark 20 in Example 5 and Comparative Example 3 were as shown in Tables 1 and 2.

[0168] Next, the cross-sectional profile of the mark 20 of the example and the comparative example was measured using an atomic force microscope. The measurement using the atomic force microscope was performed to obtain a cross-sectional profile in the direction of the width W. The measurement using the atomic force microscope was performed by scanning the range of the width W at 0.5 Hz over a length 5 times the width W. The data was collected every 20 nm, and a function y=f(x) was obtained as a curve showing a moving average of three points, which is a cross-sectional profile. The position of x=0 μm was set to the deepest position in the cross-sectional profile of the mark 20. The position of the origin (y=0 nm) of the position y in the depth direction was set to y=0 nm, with the coordinates on the surface of the multilayer reflective film-coated substrate 90 on which the mark 20 was not formed as the origin.

[0169] Next, the first differential y' = f'(x) and the second differential y'' = f''(x) of the function y = f(x) were calculated. Next, of the position x where the value of the second differential y'' = f''(x) is the minimum, the minimum value in the negative x range was defined as X1, and the minimum value in the positive x range was defined as X2. Next, for the first differential y' = f'(x) of the function y = f(x), the value T1 (= f'(X1)) at x = X1 was calculated. Similarly, for the first differential y' = f'(x) of the function y = f(x), the value T2 (= f'(X2)) at x = X2 was calculated.

[0170] The "T1 on protective film" and "T2 on protective film" columns in Tables 1 and 2 show T1 and T2 of the mark 20 formed on the multilayer reflective film-coated substrate 90 obtained as described above. T1 and T2 in the examples satisfied the following formula (1). T1 and T2 in the comparative examples did not satisfy the following formula (1).

number

[0171] Next, a defect inspection device (ABI, manufactured by Lasertec Corporation) was used to inspect the multilayer reflective film-coated substrates 90 of the example and comparative example for defects. In the defect inspection, the position of the defect was identified using a fiducial mark 20 formed in a concave shape on the protective film 3 as a reference.

[0172] Next, a reflective mask blank 100 was produced in which an absorber film 4 and an etching mask film 6 were formed on the surface (surface of the protective film 3) of the multilayer reflective film 2 of each of the examples and comparative examples on which the above-mentioned marks 20 were formed.

[0173] Specifically, an absorber film 4 consisting of a laminated film of TaBN (thickness 56 nm) and TaBO (thickness 14 nm) was formed by DC magnetron sputtering. The TaBN film was formed by reactive sputtering using a TaB target in a mixed gas atmosphere of Ar gas and N2 gas. The TaBO film was formed by reactive sputtering using a TaB target in a mixed gas atmosphere of Ar gas and O2 gas. The mark 20 of the multilayer reflective film-coated substrate 90 was transferred to the absorber film 4.

[0174] As in the case of the multilayer reflective film coated substrate 90 described above, the mark 20 of the reflective mask blank 100 of the example and comparative example was measured using an atomic force microscope to obtain a cross-sectional profile (function y=f(x)) of the mark 20. Next, the first differential y'=f'(x) and the second differential y''=f''(x) of the function y=f(x) were calculated, and among the positions x where the value of the second differential y''=f''(x) was the minimum value, the minimum value in the negative x region was designated as X1, and the minimum value in the positive x region was designated as X2. Next, in the first differential y'=f'(x) of the function y=f(x), the value T1 (=f'(X1)) at x=X1 and the value T2 (=f'(X2)) at x=X2 were calculated.

[0175] The "T1 on absorber film" and "T2 on absorber film" columns of Tables 1 and 2 show T1 and T2 of the mark 20 transferred to the absorber film 4. T1 and T2 of the examples satisfied the above formula (1). T1 and T2 of the comparative examples did not satisfy the above formula (1).

[0176] Next, an etching mask film 6 was formed on the surface (surface of the absorber film 4) of the reflective mask blank 100 of the example and comparative example to which the above-mentioned mark 20 had been transferred, thereby producing a reflective mask blank 100 with an etching mask film 6.

[0177] Specifically, a CrON film was formed as the etching mask film 6 in the examples and comparative examples. The CrON film (etching mask film 6) was formed by DC magnetron sputtering (reactive sputtering) using a Cr target and introducing a mixed gas of argon (Ar) gas at a gas flow rate of 20 sccm, oxygen (O2) gas at a gas flow rate of 10 sccm, and nitrogen (N2) gas at a gas flow rate of 10 sccm at a power of 1300 W. The thickness of the etching mask film 6 was 6 nm. The mark 20 of the multilayer reflective film-coated substrate 90 was transferred to the etching mask film 6.

[0178] As in the case of the multilayer reflective film coated substrate 90 described above, the marks 20 of the examples and comparative examples were measured using an atomic force microscope to obtain the cross-sectional profile (function y=f(x)) of the marks 20. Next, the first differential y'=f'(x) and the second differential y''=f''(x) of the function y=f(x) were calculated, and among the positions x where the value of the second differential y''=f''(x) was the minimum value, the minimum value in the negative x range was designated as X1, and the minimum value in the positive x range was designated as X2. Next, in the first differential y'=f'(x) of the function y=f(x), the value T1 (=f'(X1)) at x=X1 and the value T2 (=f'(X2)) at x=X2 were calculated.

[0179] The "T1 on Etching Mask Film" and "T2 on Etching Mask Film" columns of Tables 1 and 2 show T1 and T2 of the mark 20 transferred to the etching mask film 6. T1 and T2 in the examples satisfied the above formula (1). T1 and T2 in the comparative examples did not satisfy the above formula (1).

[0180] The concave reference mark 20 formed on the reflective mask blank 100 was detected by an electron beam lithography system. The detection of the reference mark 20 by the electron beam lithography system was performed by using multiple beams. The evaluation results are shown in "MBMW detection accuracy" in Tables 1 and 2. It was confirmed that the reference mark 20 was detectable in Examples 1 to 3, 5, and 6, and that the reference mark 20 had sufficient contrast to be detectable by the electron beam lithography system. The detection accuracy of the reference marks 20 in Examples 4 and 7 was somewhat low, but within an acceptable range. The detection accuracy of the reference marks 20 in Comparative Examples 1 to 3 was poor, and it was difficult to detect the reference marks 20.

[0181] In addition, a coordinate measuring device (PROVE, manufactured by Carl Zeiss) was used as a coordinate reference for the electron beam drawing device to detect the coordinates of the fiducial marks 20 of the example and the comparative example. As a result, the fiducial marks 20 of the example and the comparative example could be detected.

[0182] From the above, it can be said that by using the multilayer reflective film-coated substrate 90 and the reflective mask blank 100 of the embodiment on which the mark 20 of a predetermined shape is formed, it is possible to manage the defect coordinates with a higher degree of accuracy. Also, it is difficult to detect the reference mark 20 by an electron beam lithography apparatus with the multilayer reflective film-coated substrate 90 and the reflective mask blank 100 of the comparative examples 1 to 3, and therefore it is difficult to fabricate the reflective mask 200 therefrom.

[0183] Next, a reflective mask 200 was produced using the reflective mask blank 100 of the above-mentioned example. Note that in the case of the reflective mask blank 100 of the comparative example, since it was difficult to detect the reference mark 20 by the electron beam lithography apparatus as described above, the reflective mask 200 of the comparative example was not produced.

[0184] First, as shown in Fig. 7A, a resist film 11 was formed on the etching mask film 6 of the reflective mask blank 100 of the example. A predetermined pattern was then drawn (exposed) on this resist film 11, and the resist film 11 was further developed and rinsed to form a resist pattern 11a (Fig. 7B).

[0185] When the pattern was written by the electron beam writing apparatus, the coordinates of the above-mentioned mark 20 (reference mark 20) ​​on the etching mask film 6 measured by a coordinate measuring instrument (PROVE, manufactured by Carl Zeiss) were used as a reference. By using the mark 20 (reference mark 20) ​​as an FM (fiducial mark) which is a reference for the defect position, the defect coordinates based on the defect inspection instrument were converted to defect coordinates based on the coordinate measuring instrument. Then, the FM on the resist film 11 was detected by the electron beam writing apparatus. A multi-beam was used to detect the FM. The position of the defect was specified by using the FM as a reference, and the position of the resist pattern 11a was adjusted so that the defect would not adversely affect the reflective mask 200.

[0186] Next, the etching mask film 6 was dry-etched using the resist pattern 11a as a mask to form an etching mask pattern 6a (FIG. 7C). Specifically, in this embodiment, the etching mask film 6 (CrON film) was dry-etched using a mixed gas of Cl2 gas and O2 gas.

[0187] Next, the absorber film 4 was dry-etched using the etching mask pattern 6a as a mask to form the absorber pattern 4a (FIG. 7D). Specifically, in this embodiment, the upper TaBO film was dry-etched with a fluorine-based gas (CF4 gas), and then the lower TaBN film was dry-etched with a chlorine-based gas (Cl2 gas).

[0188] Thereafter, the etching mask pattern 6a was removed by dry etching (FIG. 7E). Specifically, in this embodiment, the etching mask pattern 6a (CrON film) was removed by dry etching using a mixed gas of Cl2 gas and O2 gas.

[0189] In this manner, the reflective mask 200 of the embodiment was produced.

[0190] The reflective mask 200 (transfer mask) of the example of this embodiment is a transfer mask with higher detection accuracy of the electron beam lithography apparatus, and therefore defect coordinates can be managed with high accuracy. Therefore, the reflective mask 200 of the example of this embodiment is less affected by defects and can be said to be a high-performance reflective mask 200.

[0191] When the reflective mask 200 obtained in this manner is set in an exposure tool to transfer a pattern onto a semiconductor substrate on which a resist film has been formed, good pattern transfer can be achieved without any defects in the transferred pattern caused by the reflective mask 200.

[0192] [Table 1]

[0193] [Table 2] [Explanation of symbols]

[0194] 1 Board 2 Multilayer reflective film 3 Protective film 4. Absorber membrane 4a Absorber pattern 5 Backside conductive film 6 Etching mask film 6a Etching mask pattern 11 Resist film 11a Resist pattern 20 marks (reference marks) 50 EUV exposure equipment 51 EUV light generation section 52 Laser light source 53 Tin droplet generation part 54 Capture unit 55 Collector 56 Irradiation optical system 57 Projection optical system 58 Reticle Stage 59 Wafer Stage 60 Semiconductor Substrate 90 Multilayer reflective film substrate 100 Reflective mask blank 200 Reflective mask 300 Transmissive mask blank 310 Light-shielding film 400 Transmissive mask 410 Light-shielding film pattern

Claims

1. A multilayer reflective film-coated substrate having a substrate and a multilayer reflective film disposed on the substrate, the surface of the multilayer reflective film-coated substrate has at least one concave mark; When the cross-sectional profile of the mark is represented by a function y=f(x), in the first differential y'=f'(x) of the function y=f(x), x=X １ The value of T １ and x=X ２ The value of T ２ A multilayer reflective film-coated substrate, characterized in that: [0010] x: the position of the mark in the cross-sectional profile in the width direction, with the coordinate of the center in the width direction being 0 y: Position in the depth direction perpendicular to the width direction X １ : one position in the width direction where the second derivative y″=f″(x) of the function y=f(x) is a minimum value X ２ : The other position in the width direction where the value of the second derivative y''=f''(x) is the minimum value

2. The X １ Ga-a・W≦X １ ≦b １ and X ２ GA ２ ≦X ２ 2. The multilayer reflective film coated substrate according to claim 1, satisfying ≦a·W. W: Mark width D: Depth of mark a: constant b １ The negative position in the width direction at y=-D / 3 when the coordinate in the depth direction of the surface of the multilayer reflective film-coated substrate where the mark is not present is y=0. b ２ : the positive position in the width direction when y=-D / 3

3. 3. The multilayer reflective film coated substrate according to claim 2, wherein the width W of the mark is 0.5 to 10 μm.

4. 4. The multilayer reflective film coated substrate according to claim 2, wherein the depth D of the mark is 10 to 80 nm.

5. 3. The multilayer reflective film coated substrate according to claim 1, further comprising a protective film on the multilayer reflective film.

6. A mask blank having a substrate and a thin film for forming a pattern disposed on the substrate, a surface of the mask blank having at least one concave mark; When the cross-sectional profile of the mark is represented by a function y=f(x), In the first derivative y'=f'(x) of the function y=f(x), x=X １ The value of T １ and x=X ２ The value of T ２ satisfies formula (1). [0025] x: the position of the mark in the cross-sectional profile in the width direction, with the coordinate of the center in the width direction being 0 y: Position in the depth direction perpendicular to the width direction X １ : one position in the width direction where the second derivative y″=f″(x) of the function y=f(x) is a minimum value X ２ : The other position in the width direction where the value of the second derivative y''=f''(x) is the minimum value

7. The X １ Ga-a・W≦X １ ≦b １ and X ２ GA ２ ≦X ２ The mask blank according to claim 6 , satisfying ≦a·W. W: Mark width D: Depth of mark a: constant b １ When the coordinate in the depth direction of the surface of the mask blank where the mark does not exist is y=0, the negative position in the width direction at which y=-D / 3 occurs b ２ : the positive position in the width direction when y=-D / 3

8. 8. The mask blank according to claim 7, wherein the width W of the mark is 0.5 to 10 μm.

9. 9. The mask blank according to claim 7, wherein the depth D of the mark is 10 to 80 nm.

10. 8. The mask blank according to claim 6, wherein the thin film comprises at least one selected from an absorber film, a light-shielding film, an etching mask film, and a resist film.

11. A transfer mask having a substrate and a thin film disposed on the substrate and having a pattern formed thereon, the surface of the transfer mask has at least one concave mark; When the cross-sectional profile of the mark is represented by a function y=f(x), In the first derivative y'=f'(x) of the function y=f(x), x=X １ The value of T １ and x=X ２ The value of T ２ A transfer mask, characterized in that: [0030] x: the position of the mark in the cross-sectional profile in the width direction, with the coordinate of the center in the width direction being 0 y: Position in the depth direction perpendicular to the width direction X １ : one position in the width direction where the second derivative y″=f″(x) of the function y=f(x) is a minimum value X ２ : The other position in the width direction where the value of the second derivative y''=f''(x) is the minimum value

12. The X １ Ga-a・W≦X １ ≦b １ and X ２ GA ２ ≦X ２ 12. The transfer mask according to claim 11, satisfying the condition ≦a·W. W: Mark width D: Depth of mark a: constant b １ When the coordinate in the depth direction of the surface of the transfer mask where the mark does not exist is y=0, the negative position in the width direction at which y=-D / 3 occurs b ２ : the positive position in the width direction when y=-D / 3

13. 13. The transfer mask according to claim 12, wherein the width W of the mark is 0.5 to 10 μm.

14. 14. The transfer mask according to claim 12, wherein the depth D of the mark is 10 to 80 nm.

15. 13. The transfer mask according to claim 11, wherein the thin film includes at least one selected from an absorber film and a light-shielding film.

16. Preparing a mask blank according to claim 6 or 7; and patterning the thin film using the marks as references.

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