TWI829797B - Multi-layer reflective film substrate, reflective mask substrate, reflective mask manufacturing method and semiconductor device manufacturing method - Google Patents

Abstract

Improve the conversion accuracy from the coordinate system of the defect inspection device that detects defects on the multi-layer reflective film to the coordinate system of other devices.

The substrate with the multilayer reflective film is provided with the number of reference marks determined in advance through steps (1) to (7). (1) Use the defect inspection device to obtain the first defect coordinates of defects in other substrates with multi-layer reflective films and the first reference mark coordinates of the reference marks. (2) Use a coordinate measuring device to obtain the second defect coordinates of defects in other substrates with multi-layer reflective films and the second reference mark coordinates of the reference marks. (3) Calculate a conversion coefficient for converting from the coordinate system of the defect inspection device to the coordinate system of the coordinate measuring device based on the first reference mark coordinates and the second reference mark coordinates. (4) Use the conversion coefficient calculated in (3) to convert the first defect coordinates to the third defect coordinates. (5) Find the value of 3σ based on the difference between the second defect coordinate and the third defect coordinate. (6) Obtain the corresponding relationship between the number of fiducial marks and 3σ. (7) The value of 3σ will determine the number of fiducial marks less than 50nm.

Description

Multi-layer reflective film substrate, reflective mask substrate, reflective mask manufacturing method and semiconductor device manufacturing method

The present invention relates to a multi-layer reflective film substrate, a reflective mask substrate, a manufacturing method of the reflective mask, and a manufacturing method of a semiconductor device.

In recent years, with the further requirements for higher density and higher precision of ultra-LSI components, the EUV lithography system, which uses extreme ultraviolet (EUV) light exposure technology, is highly anticipated. Here, EUV light refers to light in the wavelength band of the weak X-ray region or the vacuum ultraviolet region, specifically light with a wavelength of approximately 0.2 to 100 nm. The mask system used in EUV lithography proposes a reflective mask. A reflective mask has a multi-layer reflective film that reflects exposure light formed on a substrate such as glass or silicon, and an absorber film pattern that absorbs exposure light is formed on the multi-layer reflective film. In an exposure machine that performs pattern transfer, the light incident on the reflective mask mounted on it is absorbed in the part with the absorber film pattern, and in the part without the absorber film pattern, it is reflected by multiple layers. The film is reflected. Then, the reflected light image is transferred to a semiconductor substrate such as a silicon wafer through the reflective optical system.

As the requirements for miniaturization of the lithography process increase, the issues in the lithography process gradually become apparent. One of the issues is the problem of defect information on mask base substrates used in the lithography process.

In the past, in substrate inspection, etc., the center of the substrate was used as the origin (0,0), and the coordinate system managed by the defect inspection device was used to specify the location of the substrate defect based on the distance from the origin. Set. Therefore, the basis of the absolute coordinates is not clear, the position accuracy is low, and there will be inconsistencies in detection between devices. Furthermore, when drawing a pattern and patterning the pattern forming film to avoid defects, it is still difficult to avoid micron-level defects. Therefore, the direction of the transfer pattern will be changed, or the transfer position will be roughly shifted by mm levels to avoid defects.

Under such circumstances, a technique has been proposed in which, for example, a fiducial mark is formed on a mask base using a substrate, and the defect position is specified based on the fiducial mark. By forming fiducial marks on the mask base substrate, it is possible to prevent the fiducials used at the defective positions specified in each device from shifting.

In reflective masks that use EUV light as the exposure light, it is particularly important to accurately identify the defect locations on the multi-layer reflective film. This is because defects existing in the multilayer reflective film are not only almost impossible to correct, but may also become significant phase defects in the transfer pattern.

In order to accurately identify the defect location on the multi-layer reflective film, it is preferable to obtain the location information of the defect by performing a defect inspection after the multi-layer reflective film is formed. For this purpose, it is preferable to form the reference mark on a multilayer reflective film formed on the substrate.

Patent Document 1 discloses a method of forming micro-defects with an equivalent spherical diameter of about 30 to 100 nm on a substrate such as a reflective mask base for EUV lithography in such a manner that the position of a minute defect with an equivalent spherical diameter of about 30 nm can be accurately identified. The content of at least 3 tags.

[Prior technical literature]

[Patent Document]

Patent Document 1: International Publication No. WO2008/129914

A technology (Defect mitigation technology) is proposed, which is based on the defect data and component pattern data of the mask substrate to form an absorber film pattern where there are defects. way to correct the rendering data to mitigate defects. In order to realize such a technology, for example, in a reflective mask base in which an absorber film is formed on a multilayer reflective film, an electron line drawing machine is used to draw a pattern on the resist film formed on the absorber film. The electronic line drawing machine also uses electronic lines to detect fiducial marks, and draws patterns based on the corrected and corrected drawing data based on the detected fiducial points.

The coordinate system of the defect inspection device used to obtain the defect data of the mask substrate is different from the coordinate system of the electronic line drawing machine. Therefore, when using the fiducial marks and defect data obtained by the defect inspection device to perform electronic line drawing, it is necessary to convert the data into the coordinate system of the electronic line drawing machine.

However, when the conversion accuracy from the coordinate system of the defect inspection device to the coordinate system of electronic line drawing is very poor, when the above-mentioned Defect mitigation technology is implemented, there will be a problem that the drawing data cannot be corrected and corrected with high accuracy.

Therefore, an object of the present invention is to provide a multilayer reflective film substrate and a reflective mask substrate that can improve the conversion accuracy from the coordinate system of a defect inspection device that detects defects on a multilayer reflective film to the coordinate system of other devices. , a method of manufacturing a reflective mask and a method of manufacturing a semiconductor device.

The present inventors have made efforts to improve the accuracy of conversion from the coordinate system of a defect inspection device that detects defects on a multilayer reflective film to the coordinate system of other devices. As a result, it was discovered that there is a correlation between the number of reference marks that serve as the reference for the defect position and the coordinate conversion accuracy, and the present invention was completed.

In order to solve the above-mentioned problems, the present invention has the following structure.

(composition 1)

A multi-layer reflective film substrate having a substrate and a multi-layer reflective film formed on the substrate and reflecting EUV light; and having a reference that can serve as a position reference for defects in the multi-layer reflective film substrate mark; the number of the fiducial marks is the number obtained in advance through the following processes (1) to (7); (1) Obtaining a plurality of fiducial marks by a defect inspection device with the first coordinate system The first defect coordinates of the defects in other substrates with multi-layer reflective films and the first datum mark coordinates of the reference marks; (2) Obtain the first coordinates of the defects in other substrates with multi-layer reflective films by using a coordinate measuring device with a second coordinate system The second defect coordinates of the defect and the second datum mark coordinates of the datum mark; (3) Calculate the direction from the first coordinate system to the second coordinate system based on the first datum mark coordinates and the second datum mark coordinates. The conversion coefficient for coordinate conversion; (4) Use the conversion coefficient calculated in (3) to convert the first defect coordinate obtained by the defect inspection device in the above (1) to the second coordinate system. The third defect coordinate conversion of the benchmark; (5) Find the difference between the second defect coordinate obtained by the coordinate measuring instrument in the above (2) and the third defect coordinate converted in the above (4) Obtain the value of 3σ; (6) Obtain the corresponding relationship between the number of fiducial marks and 3σ; and (7) The value of 3σ will determine the number of fiducial marks less than 50nm.

(composition 2)

For example, in the substrate with a multi-layer reflective film of composition 1, the number of the reference marks is 8 or more.

(composition 3)

For example, in the substrate with a multi-layer reflective film constituting 1 or 2, the number of the reference marks is 8 or more.

(Constitution 4)

A reflective mask substrate includes: a substrate with a multi-layer reflective film as described in any one of components 1 to 3; and a laminated film formed on the substrate with a multi-layer reflective film.

(Constitution 5)

A reflective mask substrate has: a multi-layer reflective film substrate having a substrate and a multi-layer reflective film formed on the substrate and reflecting EUV light; and a laminated film formed on the multi-layer reflective film substrate ; The substrate with a multi-layer reflective film is provided with a fiducial mark that becomes a positional reference for defects in the substrate with a multi-layer reflective film; the laminated film is provided with a transfer fiducial mark on which the fiducial mark is transferred; the fiducial mark is The number is a number obtained in advance through the following steps (1) to (7); (1) Obtaining other multi-layer reflective film substrates having a plurality of reference marks through a defect inspection device with a first coordinate system The first defect coordinates of the defect and the first fiducial mark coordinates of the fiducial mark; (2) Obtain the laminated film that will be formed on the other substrate with a multi-layer reflective film by using a coordinate measuring device with a second coordinate system The second defect coordinates of the defect in the reflective mask substrate and the second fiducial mark coordinates of the transfer fiducial mark; (3) Calculate from the first fiducial mark coordinates based on the first fiducial mark coordinates and the second fiducial mark coordinates The conversion coefficient used to convert the coordinate system to the coordinates of the second coordinate system; (4) Use the conversion coefficient calculated in (3) to convert the first defect coordinate obtained by the defect inspection device in (1) above Convert to the third defect coordinate based on the second coordinate system; (5) Find the value of 3σ based on the difference between the second defect coordinate obtained by the coordinate measuring machine in the above (2) and the third defect coordinate converted in the above (4); (6) Obtain the corresponding relationship between the number of fiducial marks and 3σ; and (7) the value of 3σ will determine the number of fiducial marks less than 50nm.

(composition 6)

For example, if the reflective mask base 5 is formed, the number of the reference marks is 8 or more.

(composition 7)

For example, if a reflective mask base of 5 or 6 is formed, the number of the fiducial marks is more than 16.

(composition 8)

For example, the reflective mask substrate of any one of items 4 to 7 is constituted, wherein the laminated film includes an absorber film that absorbs EUV light.

(Composition 9)

A method of manufacturing a reflective mask includes the step of forming a laminated film pattern on the laminated film in the reflective mask base of the composition 4 or 8.

(composition 10)

A method of manufacturing a semiconductor device includes a step of forming a transfer pattern on a semiconductor substrate using a reflective mask manufactured by the reflective mask manufacturing method of the configuration 9.

According to the present invention, it is possible to provide a multilayer reflective film substrate and a reflective mask substrate that can improve the conversion accuracy from the coordinate system of a defect inspection device that detects defects on a multilayer reflective film to the coordinate system of other devices. Furthermore, according to the present invention, it is possible to provide a method of manufacturing a reflective mask that uses the multi-layer reflective film substrate or the reflective mask substrate and performs drawing data correction based on the defect information to reduce defects. Methods and methods of manufacturing semiconductor devices.

10:Substrate with multi-layer reflective film

12:Substrate

14:Multilayer reflective film

18:Protective film

20: fiducial mark

28:Laminated film

30: Reflective mask base

40: Reflective mask

50:Pattern transfer device

56:Semiconductor substrate

FIG. 1 is a schematic cross-sectional view showing a substrate with a multi-layer reflective film.

Figure 2 is a top view of a substrate with a multi-layer reflective film and an enlarged view of the fiducial mark.

FIG. 3 is a schematic diagram showing a cross-section of a reflective mask substrate.

FIG. 4 is a schematic diagram showing a manufacturing method of a reflective mask.

Figure 5 shows a pattern transfer device.

Figure 6 shows the FM formation position when the number of FMs is eight.

Figure 7 is a graph showing the value of 3σ when the number of FMs is 3 to 8.

FIG. 8 is a graph showing the calculation results of 3σ when the number N of fiducial marks is increased to 200.

FIG. 9 shows the FM formation positions when the number of FMs is 16.

Figure 10 shows the formation positions of AM and FM when the number of AMs is 28 and the number of FMs is 4.

Figure 11 shows the FM formation position when the number of FMs is three.

(First Embodiment)

Hereinafter, embodiments of the present invention will be described in detail.

[Substrate with multi-layer reflective film]

FIG. 1 is a schematic cross-sectional view showing a substrate with a multi-layer reflective film.

As shown in FIG. 1 , the substrate 10 with a multilayer reflective film includes a substrate 12 and a multilayer reflective film 14 that reflects EUV light as exposure light. Furthermore, the substrate 10 with the multi-layer reflective film may be provided with a protective film 18 for protecting the multi-layer reflective film 14 . In this embodiment, a multi-layer reflective film 14 is formed on the substrate 12. A protective film 18 is formed on the multilayer reflective film 14 . As described below, the substrate 10 with the multilayer reflective film is provided with four or more reference marks that serve as references for defective locations.

In addition, in this specification, "on" a substrate or a film does not only mean contacting the upper surface of the substrate or film, but also includes not contacting the upper surface of the substrate or film. That is, "on" a substrate or film includes a case where a new film is formed above the substrate or film, a case where another film is interposed between the substrate or film, and the like. Also, the so-called "upper" does not necessarily mean the upper side in the vertical direction. The so-called "upper" simply means the relative positional relationship of the substrate, film, etc.

<Substrate>

The substrate 12 used as the multilayer reflective film substrate 10 of this embodiment is preferably used in EUV exposure to prevent the absorber film pattern from being distorted due to heat during exposure, and has 0±5 ppb/ Low thermal expansion coefficient within the range of ℃. Examples of materials having a low thermal expansion coefficient within this range include SiO ₂ -TiO ₂ glass, multi-component glass ceramics, and the like.

The main surface of the side on which the transfer pattern (the absorber film pattern described below corresponds) of the substrate 12 is formed is preferably processed in order to improve the flatness. By improving the flatness of the main surface of the substrate 12, the position accuracy and transfer accuracy of the pattern can be improved. For example, in the case of EUV exposure, in an area of 132 mm × 132 mm on the main surface of the transfer pattern side of the substrate 12, the flatness is preferably 0.1 μm or less, more preferably 0.05 μm or less, and most optimal The ground system is below 0.03μm. In addition, the main surface opposite to the side on which the transfer pattern is formed is fixed to the surface of the exposure device by an electrostatic clamp, and the flatness in an area of 142 mm × 142 mm is 1 μm or less, more preferably 0.5 μm or less. , optimally below 0.03μm. In addition, the flatness in this specification refers to the numerical value of surface warpage (deformation) represented by TIR (Total Indicated Reading), with the substrate surface as the reference and the plane determined by the least squares method as the focus. plane, which is the absolute value of the height difference between the highest position of the substrate surface above the focal plane and the lowest position of the substrate surface below the focal plane.

In the case of EUV exposure, the surface roughness of the main surface of the side of the substrate 12 on which the transfer pattern is formed is preferably a root mean square roughness (RMS) of 0.1 nm or less. In addition, surface roughness can be measured with an atomic force microscope.

The substrate 12 preferably has high rigidity in order to prevent deformation due to film stress of the film (multilayer reflective film 14 and the like) formed thereon. In particular, the substrate 12 preferably has a high Yang formula of 65 GPa or more.

<Multilayer reflective film>

The substrate 10 with a multi-layer reflective film includes a substrate 12 and a multi-layer reflective film 14 formed on the substrate 12 . The multilayer reflective film 14 is composed of, for example, a multilayer film in which elements with different refractive indexes are periodically stacked. The multilayer reflective film 14 has the function of reflecting EUV light.

Generally speaking, the multilayer reflective film 14 is composed of thin films of light elements or compounds thereof that are high refractive index materials (high refractive index) and thin films of heavy elements or compounds thereof with low refractive index alternately laminated (low refractive index). It is composed of multi-layer films with approximately 40 to 60 cycles.

In order to form the multi-layer reflective film 14, high refractive index layers and low refractive index layers may be sequentially stacked from the substrate 12 in a plurality of periods. In this case, one (high refractive index layer/low refractive index layer) laminated structure constitutes one period.

In order to form the multi-layer reflective film 14, low refractive index layers and high refractive index layers may be sequentially stacked from the substrate 12 in a plurality of periods. In this case, one (low refractive index layer/high refractive index layer) laminated structure constitutes one period.

In addition, the uppermost layer of the multilayer reflective film 14, that is, the surface layer of the multilayer reflective film 14 on the opposite side to the substrate 12, is preferably a high refractive index layer. When the high refractive index layer and the low refractive index layer are sequentially stacked from the substrate 12 side, the uppermost layer will be the low refractive index layer. However, the low refractive index layer is a multilayer reflective film 14 In the case of the surface, because the low refractive index layer will be easily oxidized, which will reduce the reflectivity of the multi-layer reflective film, a high refractive index layer will be formed on the low refractive index layer. On the other hand, when the low refractive index layer and the high refractive index layer are sequentially stacked from the substrate 12 side, the uppermost layer becomes the high refractive index layer. In this case, the uppermost high refractive index layer becomes the surface of the multilayer reflective film 14 .

In this embodiment, the high refractive index layer may be a layer containing Si. The high refractive index layer may contain Si monomer or Si compound. The Si compound may contain at least one element selected from the group consisting of Si, B, C, N, and O. By using a layer containing Si as a high refractive index layer, a multilayer reflective film with excellent reflectivity for EUV light can be obtained.

In this embodiment, as the low refractive index material, at least one element selected from the group consisting of Mo, Ru, Rh, and Pt can be used, or at least one element selected from the group consisting of Mo, Ru, Rh, and Pt can be used. An alloy of 1 element.

For example, as the multilayer reflective film 14 for EUV light with a wavelength of 13 to 14 nm, it is preferable to use a Mo/Si multilayer film in which Mo films and Si films are alternately cyclically laminated. Other multilayer reflective films used in the EUV light region include Ru/Si periodic multilayer films, Mo/Be periodic multilayer films, Mo compound/Si compound periodic multilayer films, Si/Nb periodic multilayer films, and Si/Mo. /Ru periodic multilayer film, Si/Mo/Ru/Mo periodic multilayer film, Si/Ru/Mo/Ru periodic multilayer film, etc. The material of the multi-layer reflective film can be selected by taking the exposure wavelength into consideration.

The reflectivity of the multilayer reflective film 14 alone is, for example, 65% or more. The upper limit of the reflectivity of the multilayer reflective film 14 is, for example, 73%. In addition, the thickness and period of the layers included in the multilayer reflective film 14 can be selected in a manner that satisfies Bragg's law.

The multilayer reflective film 14 can be formed by conventional methods. The multilayer reflective film 14 is formed by, for example, ion beam sputtering.

For example, when the multilayer reflective film 14 is a Mo/Si multilayer film, a Mo film with a thickness of about 3 nm is formed on the substrate 12 by an ion beam sputtering method and using a Mo target. Next, a Si target is used to form a Si film with a thickness of approximately 4 nm. By repeating this operation, a multilayer reflective film 14 in which 40 to 60 periods of Mo/Si films are laminated can be formed. At this time, the surface layer of the multilayer reflective film 14 on the opposite side to the substrate 12 is a layer containing Si (Si film). The thickness of the Mo/Si film for one cycle is 7 nm.

<Protective film>

The substrate 10 with the multilayer reflective film of this embodiment may include a protective film 18 formed on the multilayer reflective film 14 . The protective film 18 has the function of protecting the multilayer reflective film 14 during patterning or pattern correction of the absorber film described below. The protective film 18 is provided, for example, between the multilayer reflective film 14 and the absorber film.

As the material of the protective film 18, for example, Ru, Ru-(Nb, Zr, Y, B, Ti, La, Mo, Co or Re) compound, Si-(Ru, Rh, Cr or B) compound, Si, Materials such as Zr, Nb, La, B, etc. In addition, it can be used for compounds to which nitrogen, oxygen or carbon are added. Among them, when materials containing ruthenium (Ru) are used, the reflectivity characteristics of the multi-layer reflective film will be better. Specifically, the material of the protective film 18 is preferably Ru or Ru-(Nb, Zr, Y, B, Ti, La, Mo, Co or Re) compounds. The thickness of the protective film is, for example, 1 nm to 5 nm. The protective film 18 can be formed by conventional methods. The protective film 18 can be formed by, for example, pulse magnetron sputtering or ion beam sputtering.

The substrate 10 with the multi-layer reflective film may further have an inner conductive film on the main surface of the substrate 12 opposite to the side on which the multi-layer reflective film 14 is formed. The inner conductive film is used when the multilayer reflective film substrate 10 or the reflective mask substrate is adsorbed by an electrostatic clamp.

The substrate 10 with the multi-layer reflective film may include a base film formed between the substrate 12 and the multi-layer reflective film 14 . The base film is formed for the purpose of, for example, improving the smoothness of the surface of the substrate 12 . The base film is formed for the purpose of reducing defects, improving the reflectivity of the multilayer reflective film, correcting the stress of the multilayer reflective film, etc.

<fiducial mark>

FIG. 2 is a top view of the substrate 10 with a multilayer reflective film in this embodiment.

As shown in FIG. 2 , reference marks 20 are respectively formed near four corners of a substantially rectangular substrate 10 with a multilayer reflective film. The reference mark 20 is a mark used as a reference for the defect position in the defect information. Although FIG. 2 shows an example in which four fiducial marks 20 are formed, the number of fiducial marks 20 may be four or more. In addition, four or more reference marks 20 are sufficient as long as they can be arranged on at least two axes.

In the multi-layer reflective film substrate 10 shown in FIG. 2, the area inside the dotted line A (the area of 132mm×132mm) will have an absorber film pattern formed when manufacturing the reflective mask. The area outside the dotted line A will not have an absorber film formed when manufacturing the reflective mask. The reference mark 20 is preferably formed in an area where the absorber film pattern is not formed, that is, on or outside the dotted line A.

As shown in FIG. 2 , the reference mark 20 has a substantially cross shape. The widths W1 and W2 of the fiducial marks 20 having a substantially cross-shaped shape are, for example, 200 nm or more and 10 μm or less. The length L of the reference mark 20 is, for example, 100 μm or more and 1500 μm or less. Although FIG. 2 shows an example of the fiducial mark 20 having a substantially cross-shaped shape, the shape of the fiducial mark 20 is not limited thereto. The shape of the fiducial mark 20 may be approximately L-shaped, circular, triangular, quadrangular, etc. when viewed from above.

The cross-sectional shape of the reference mark 20 is, for example, a concave shape. The “concave shape” here means that when observing the cross section of the multilayer reflective film substrate 10 (a cross section perpendicular to the main surface of the multilayer reflective film substrate 10 ), the fiducial mark 20 is concave downward, for example, in a step shape or curve. shape to form. The depth D of the concave reference mark 20 is preferably 30 nm or more. The depth D of the fiducial mark 20 may be the depth at which the substrate 12 is exposed, and is preferably 100 nm or less, more preferably 50 nm or less. In the case where depth D is small, Then the effect of the present invention can be obtained more significantly. The depth D represents the vertical distance from the surface of the multi-layer reflective film substrate 10 to the deepest position of the bottom of the reference mark 20 .

The method of forming the fiducial mark 20 is not particularly limited. The fiducial mark 20 can be formed on the surface of the multi-layer reflective film substrate 10 by laser processing, for example. At this time, the fiducial mark 20 may be formed after the multilayer reflective film 14 is formed, and then the protective film 18 is formed. Alternatively, the multilayer reflective film 14 and the protective film 18 may be formed, and then the fiducial mark 20 is formed. Laser processing conditions are as follows.

Laser type (wavelength): ultraviolet ~ visible light range. For example, a semiconductor laser with a wavelength of 405nm.

Laser output: 1~120mW

Scanning speed: 0.1~20mm/s

Pulse frequency: 1~100MHz

Pulse width: 3ns~1000s

The laser used when laser processing the fiducial mark 20 can be a continuous wave or a pulse wave. When a pulse wave is used, compared with a continuous wave, even if the depth D of the fiducial mark 20 is the same, the width W of the fiducial mark 20 can still be reduced. Therefore, when a pulse wave is used, the contrast will be greater than that of a continuous wave, and the fiducial mark 20 can be easily detected by a defect inspection device or an electronic line drawing device.

The method of forming the fiducial mark 20 is not limited to laser. The fiducial mark 20 can be formed by, for example, photolithography, FIB (clustered ion beam), processing traces swept by a diamond needle, dents caused by micro-pressure parts, embossing caused by imprinting, etc.

The cross-sectional shape of the reference mark 20 is not limited to a concave shape. For example, the cross-sectional shape of the reference mark 20 may be a convex shape protruding upward. When the cross-sectional shape of the reference mark 20 is convex, it can be formed by partial film formation such as FIB or sputtering. The height H of the convex reference mark 20 is preferably Department is above 30nm. The height H of the reference mark 20 is preferably 100 nm or less, more preferably 50 nm or less. When the height H is smaller, the effect of the present invention can be obtained more significantly. The height H refers to the distance in the vertical direction from the surface of the multilayer reflective film substrate 10 to the highest position of the reference mark 20 .

When the fiducial mark 20 is formed on the substrate 10 with the multilayer reflective film, the coordinates of the fiducial mark 20 and the defect are obtained with high precision by a defect inspection device. Next, an absorber film is formed on the protective film 18 of the multilayer reflective film substrate 10 . Next, a resist film is formed on the absorber film. A hard mask film (or etching mask film) may be formed between the absorber film and the resist film.

The concave reference mark 20 formed on the substrate 10 with the multilayer reflective film will be transferred to the absorber film and the resist film. When the hard mask film is formed between the absorber film and the resist film, the concave reference mark 20 formed on the multilayer reflective film substrate 10 will be transferred to the absorber film, the hard mask film and the resist film. agent film.

Therefore, the fiducial mark 20 formed on the multilayer reflective film substrate 10 needs to have high contrast that can be detected by a defect inspection device. As a defect inspection device, for example, a mask for EUV exposure made by Lasertec Corporation with an inspection light source wavelength of 266 nm, a substrate/substrate defect inspection device "MAGIC SM7360", an EUV mask made by KLA-Tencor Corporation with an inspection light source wavelength of 193 nm, and a mask can be used. Mask/substrate defect inspection device "Teron600 series, such as Teron610" or ABI (Actinic Blank Inspection) device whose inspection light source wavelength is the same as the exposure light source wavelength of 13.5nm.

In addition, the reference mark 20 transferred to the absorber film and/or the resist film thereon needs to have high contrast that can be detected by a coordinate measuring machine and/or an electronic line drawing device. As a coordinate measuring device, for example, the "LMS-IPRO4" manufactured by KLA-Tencor, which uses a laser with a wavelength of 365 nm for coordinate measurement, and the "LMS-IPRO4" manufactured by Carl Zeiss, which uses a laser with a wavelength of 193 nm, can be used. "PROVE" and/or a coordinate measuring device mounted on an electronic line drawing device. The effect of the present invention can be obtained more significantly if the coordinate measuring instrument has a different wavelength from that of the defect inspection device.

The fiducial mark 20 can be used as an FM (FIDUCIAL MARK), for example. FM is a mark used as a reference for defect coordinates when drawing a pattern with an electronic line drawing device. FM is usually a cross shape as shown in Figure 2.

By using the fiducial mark 20 as FM, defect coordinates can be managed with high precision. When drawing a pattern on the resist film using an electronic line drawing device, the reference mark 20 transferred to the resist film is used as the FM of the defect position reference. For example, if FM is detected by an electronic line drawing device, the defect coordinates obtained by the defect inspection device can be converted into the coordinate system of the electronic line drawing device. Thereby, the drawing data of the pattern drawn by the electronic line drawing device can be corrected such that the defects are arranged under the absorber film pattern, for example. By correcting the drawing data, the impact of defects on the final reflective mask can be reduced.

The reference mark 20 can also be used as an AM (alignment mark). AM is a mark that can be used as a reference for defect coordinates when inspecting defects on the multilayer reflective film substrate 10 in a defect inspection device. However, the AM system is not used directly when drawing patterns with an electronic line drawing device. The shape of AM when viewed from above is, for example, a circle, a square, or a cross.

When the AM is formed on the substrate 10 with the multilayer reflective film, FM is formed on the substrate 10 with the multilayer reflective film using the following laminated film. Although AM will be transferred to the laminated film, the detection accuracy of AM can be improved by partially removing the laminated film on AM. AM systems can be detected by defect inspection devices and coordinate measuring machines. FM systems can be inspected with coordinate measuring machines and electronic line drawing devices. Since both AM and FM can be detected by a coordinate measuring machine, their relative positional relationship can be managed with high precision. Thus, the missing The AM-based defect coordinates obtained by the defect inspection device are converted with high precision into FM-based defect coordinates used by the electronic line drawing device. In addition, the number of AMs will be greater than the number of FMs.

The substrate 10 with a multilayer reflective film in this embodiment is provided with four or more (for example, N) reference marks 20 (four reference marks in FIG. 2 ) that serve as position references for defects in the substrate 10 with a multilayer reflection film. , the value of 3σ obtained through the following steps (1) to (5) is less than 50 nm.

(1) Obtain the first defect coordinates of the defect in the multilayer reflective film substrate 10 and the first reference mark coordinates of the reference mark 20 through a defect inspection device having a first coordinate system.

(2) Obtain the second defect coordinates of the defect in the multi-layer reflective film substrate 10 and the second reference mark coordinates of the reference mark 20 by using a coordinate measuring instrument with a second coordinate system.

(3) Calculate a conversion coefficient for converting the coordinates from the first coordinate system of the defect inspection device to the second coordinate system of the coordinate measuring device based on the first reference mark coordinates and the second reference mark coordinates.

(4) Use the conversion coefficient calculated in the above (3) to convert the first defect coordinate obtained by the defect inspection device in the above (1) to the third defect based on the second coordinate system of the coordinate measuring machine. Coordinate conversion.

(5) Find the value of 3σ based on the difference between the second defect coordinate obtained by the coordinate measuring machine in the above (2) and the third defect coordinate converted in the above (4).

In the above-mentioned step (1), the first defect coordinates of the defects in the multilayer reflective film substrate 10 and the first reference mark coordinates (x, y) of the N reference marks 20 are obtained by a defect inspection device. As the defect inspection device, for example, the above-described defect inspection device can be used. Furthermore, the number of defects used to obtain the numerical value of 3σ is preferably 3 or more, more preferably 9 or more, and most preferably 15 or more. In addition, it is preferable that the size difference among the N fiducial marks is small. For example, the size of the N fiducial marks is preferably within ±5% of the average value, and more preferably within ±3%. The "size" here means, for example, the area of the reference mark when viewed from above.

In the above-mentioned step (2), a coordinate measuring device is used to obtain the second defect coordinates of the defect in the multilayer reflective film substrate 10 and the second reference mark coordinates (u, v) of the N reference marks 20 . As the coordinate measuring device, for example, the above-mentioned coordinate measuring device can be used.

When detecting coordinates in the above steps (1) and (2), the origin may be set at the center of the substrate, for example. Alternatively, the edge coordinates of 8 positions (2 positions on each side) of the four sides of the substrate can be obtained, and after appropriate tilt correction is performed, the origin can be set at any corner of the substrate.

As shown in FIG. 2 , when the shape of the fiducial mark 20 is a cross, the coordinate system of the fiducial mark 20 can be set between the center line of the width W1 and the width W2 between the edges by detecting the edges of the fiducial mark 20 . The intersection of the center lines.

In the above step (3), the first reference mark coordinates (x, y) of the N reference marks 20 obtained in the step (1) and the second reference mark coordinates (x, y) of the N reference marks 20 obtained in the step (2) are used. The reference mark coordinates (u, v) are used to calculate the conversion coefficient for converting the coordinates from the first coordinate system of the defect inspection device to the second coordinate system of the coordinate measuring device. The conversion coefficient can be calculated using, for example, linear transformation (Affine Transformation). Below, an example of a method of calculating the conversion coefficient using affine conversion will be explained.

There are n pieces of coordinate data (x ₁ , y ₁ ), (x ₂ , y ₂ ), ... (x _n , y _n ) obtained by the defect inspection device, and data obtained by the coordinate measuring instrument corresponding to them. When n pieces of coordinate data (u ₁ , v ₁ ), (u ₂ , v ₂ ),... (u _n , v _n ) are obtained, move from the first coordinate system of the defect inspection device to the second coordinate system of the coordinate measuring device. The transformation system of the coordinate system can use affine transformation.

Since the conversion coefficients related to the affine transformation system x and y are independent, the x and y systems can be solved separately. Taking the x-related formula as _an example, when the _{i -} th coordinate data is brought into the affine conversion formula, it will become The formula doesn't hold. The error amount δi is simply the right minus the left side, and becomes δ _i =au _i +bv _i +cx _i .

Here, when there are n pieces of coordinate data, a formula related to n pieces of error amounts can be established. Use the least squares method to find a, b, and c that minimize the amount of errors. Here, the error function φ of the sum of squares is expressed by the following mathematical formula.

Since this function φ is a quadratic function, in order to find the minimum a, b, and c of this function, this mathematical expression will be partially differentiated with a, b, and c. When performing partial differentiation, it becomes a function representing the gradient of the error function, so the point where the function after partial differentiation becomes 0 is the minimum value, and it is also the minimum value. When expressed mathematically, it is as follows.

Since these mathematical expressions are linear simultaneous equations, when organized using determinants, the following determinants can be obtained. If we solve these simultaneous equations, we can find a, b, c with the smallest error, which is the conversion coefficient. Although it has been explained with respect to x, it can be solved similarly with respect to y.

[Mathematical formula 3]

In the above-mentioned step (4), the conversion coefficient calculated in the above-mentioned (3) is used to convert the first defect coordinate obtained by the defect inspection device in the above-mentioned (1) to the second coordinate system of the coordinate measuring device. The coordinate conversion can use, for example, the affine conversion formula x _i =au _i +bv _i +c.

In the above-mentioned step (5), the value of 3σ is obtained based on the difference between the second defect coordinate obtained by the coordinate measuring machine in the above-mentioned (2) and the third defect coordinate converted by the above-mentioned (4). . That is, the value of 3σ is obtained from the difference between the second defect coordinate "actually" obtained by the coordinate measuring device and the third defect coordinate converted to the second coordinate system of the coordinate measuring device using the conversion coefficient. 3σ is three times the standard deviation σ. The smaller 3σ means that the conversion accuracy from the first coordinate system of the defect inspection device to the second coordinate system of the coordinate measuring device will be higher.

For example, in the above (2), the coordinates of the second defect obtained by the coordinate measuring machine are (s _j , t _j ), and in the above (4), the third defect is converted to the second coordinate system of the coordinate measuring machine. When the coordinates are (S _j ,T _j ), the difference between these coordinates is (s _j -S _j ,t _j -T _j ). In this case, for each x-coordinate and y-coordinate system, the value of 3σ can be obtained by, for example, calculating the standard deviation σ of j pieces of data.

As described below, the inventor found that when the number of reference marks 20 is N, 3σ tends to be inversely proportional to N ^1/2 . That is, it is found that when the proportionality constant is α, the following formula is established.

3σ=α/N ^1/2 ...(1)

The numerical value of α can be obtained by applying the result of measuring 3σ by actually changing the number of fiducial marks 20 to the above formula (1), and then using the least squares method.

Therefore, the greater the number of fiducial marks 20 , the more the defect coordinate conversion accuracy can be improved, and the number of fiducial marks 20 can be determined based on the desired 3σ. The number of reference marks 20 is preferably 4 or more so that 3σ can be less than 50 nm. In addition, the number of reference marks 20 is more preferably 8 or more, so that 3σ can be less than 25 nm. In addition, the number of reference marks 20 is preferably 16 or more, so that 3σ can be less than 20 nm. In addition, from the viewpoint of increasing the number of steps for forming the reference marks 20 and increasing defects when there are too many reference marks 20, the number of the reference marks 20 is preferably 100 or less. Furthermore, when the number of reference marks 20 exceeds 60, the reduction range of 3σ tends to decrease. Therefore, the number of reference marks 20 is preferably 60 or less.

The value of 3σ obtained through the above-mentioned steps (1) to (5) of the multi-layer reflective film substrate 10 of this embodiment is less than 50 nm. Preferably, the value of 3σ is less than 50 nm for both x-coordinate and y-coordinate data. By setting the value of 3σ to less than 50 nm, the conversion accuracy from the first coordinate system of the defect inspection device to the second coordinate system of the coordinate measuring device can be improved.

Thereby, the user who is provided with the substrate 10 with the multi-layer reflective film can accurately compare the defect location and drawing data specified by the defect inspection device, and can accurately determine the defect position in the final manufactured reflective mask. to reduce defects.

(Second Embodiment)

The second embodiment uses another multi-layer reflective film substrate to obtain the correspondence between the number of fiducial marks and 3σ, and the multi-layer reflective film substrate has a number of fiducial marks determined based on the correspondence. It is different from the first embodiment. Other than that, everything is the same as the first embodiment.

That is, the multi-layer reflective film substrate 10 of this embodiment is provided with reference marks 20 that serve as positional references for defects in the multi-layer reflective film substrate 10. The number of the reference marks 20 is determined by the following process ( The number obtained in advance from 1) to (7).

(1) Obtain the first defect coordinates of defects in other multi-layer reflective film substrates having plural reference marks and the first reference mark coordinates of the reference marks through a defect inspection device having a first coordinate system.

(2) Obtain the second defect coordinates of the defect in the other substrate with a multi-layer reflective film and the second reference mark coordinates of the reference mark by using a coordinate measuring instrument with a second coordinate system.

(3) Calculate a conversion coefficient for converting coordinates from the first coordinate system to the second coordinate system based on the first reference mark coordinates and the second reference mark coordinates.

(4) Use the conversion coefficient calculated in the above (3) to convert the first defect coordinate obtained by the defect inspection device in the above (1) to the third defect coordinate based on the second coordinate system. Convert.

(5) Find the value of 3σ based on the difference between the second defect coordinate obtained by the coordinate measuring device in the above (2) and the third defect coordinate converted in the above (4).

(6) Obtain the corresponding relationship between the number of fiducial marks and 3σ.

(7) Determine the number of fiducial marks that have a desired value of 3σ (for example, less than 50 nm).

The above-mentioned steps (1) to (5) are the same as the steps (1) to (5) of the first embodiment, except that other substrates with multi-layer reflective films are used.

Defects in other substrates with multi-layer reflective films can be actual defects or programmed defects.

Furthermore, the other multi-layer reflective film substrate may be one multi-layer reflective film substrate on which N reference marks are formed. In this case, the above-mentioned steps (1) to (6) will be performed on a substrate with a multi-layer reflective film, and the correspondence between the number of reference marks and 3σ will be obtained, and the step (7) will be determined based on the correspondence. The number of fiducial marks.

Other multi-layer reflective film substrates may be a plurality of multi-layer reflective film substrates on which 4 to N different reference marks are formed. In this case, the above-mentioned steps (1) to (5) are performed on each multi-layer reflective film substrate. In step (6), the corresponding relationship between the number of reference marks and 3σ is obtained, and in step (7), based on the The number of fiducial marks is determined based on the corresponding relationship.

Since in this embodiment, another substrate with a multi-layer reflective film is used to determine the number of fiducial marks, the optimal number of fiducials can be obtained according to the shape of the fiducial mark, the defect inspection device and/or the coordinate measuring machine. The substrate 10 with a multi-layer reflective film is marked 20 .

(Third Embodiment)

(Reflective mask base)

FIG. 3 is a schematic cross-sectional view showing the reflective mask substrate 30 of this embodiment. The reflective mask substrate 30 of this embodiment can be manufactured by forming the laminated film 28 on the protective film 18 of the multilayer reflective film substrate 10 . Although not particularly limited, the laminated film 28 may be an absorber film that absorbs EUV light. Hereinafter, an example in which the laminated film 28 is an absorber film will be described.

The absorber film system has the function of absorbing EUV light which is the exposure light. That is, the difference between the reflectivity of the multilayer reflective film 14 (including the protective film 18 when provided) with respect to EUV light and the reflectance of the absorber film with respect to EUV light becomes greater than a predetermined value. For example, the reflectivity of the absorber film with respect to 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 14 and the light reflected by the absorber film. In addition, in this case, the absorber film in the reflective mask base 30 may be called a phase transfer film.

The absorber film preferably has the function of absorbing EUV light and can be removed by etching. The absorber film can preferably be etched by dry etching with chlorine (Cl)-based gas or fluorine (F)-based gas. As long as the absorbent film has such a function, the material of the absorbent film is not particularly limited.

The absorbent film may be a single layer or may have a laminated structure. When the absorbent film 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 absorbent film has a laminated structure, the material or composition may be changed stepwise and/or continuously in the thickness direction of the film.

The material of the absorber film is preferably, for example, tantalum alone or a material containing Ta. The material containing Ta is, for example, a material containing Ta and B, a material containing Ta and N, a material containing at least one of Ta and B, O and N, a material containing Ta and Si, or a material containing Ta, Si and N , materials containing Ta and Ge, materials containing Ta, Ge and N, materials containing Ta and Pd, materials containing Ta and Ru, materials containing Ta and Ti, etc.

The absorber film system may include a material selected from, for example, Ni monomer, Ni-containing material, Cr monomer, Cr-containing material, Ru monomer, Ru-containing material, Pd monomer, Pd-containing material, Mo monomer, and Mo monomer. At least one of the groups composed of Mo materials.

The thickness of the absorber film is preferably 30nm~100nm.

The absorber film can be formed by conventional methods, such as pulse magnetron sputtering or ion beam sputtering.

In the reflective mask substrate 30 of this embodiment, the resist film 32 can be formed on the absorber film (laminated film 28). Figure 3 shows this aspect. After the resist film 32 is patterned and exposed using an electronic line drawing device, the resist pattern can be formed by undergoing a development process. By dry etching the absorber film using this resist pattern as a mask, a pattern can be formed on the absorber film.

In the reflective mask substrate 30 of this embodiment, the laminated film 28 may include an absorber film and a hard mask film formed on the absorber film. The hard mask film is used as a mask when patterning the absorber film. The hard mask film and the absorber film differ in their etching selectivity from each other. materials to form. In the case where the material of the absorber film contains tantalum or a tantalum compound, the material of the hard mask film preferably contains chromium or a chromium compound. The chromium compound preferably contains Cr and at least one selected from the group consisting of N, O, C, and H.

The reflective mask substrate 30 of this embodiment is provided with four or more (for example, N) reference marks 20 that serve as position references for defects in the multilayer reflective film substrate 10 . The absorber film (laminated film 28) formed on the multilayer reflective film substrate 10 may have a transferred reference mark having a shape in which the reference mark 20 is transferred. For example, when the reference mark 20 is concave, the absorber film (laminated film 28) formed thereon is formed with a concave transfer reference mark. Furthermore, when the reference mark 20 is convex, the absorber film (laminated film 28) formed thereon is formed with a convex transfer reference mark.

The fiducial mark 20 of this embodiment is the same as the fiducial mark 20 of the first embodiment. For example, when the reference mark 20 has a substantially cross shape, the transfer reference mark also has a substantially cross shape. The widths W1' and W2' of the transfer reference mark having a substantially cross-shaped shape are, for example, 200 nm or more and 10 μm or less. The offset ΔW (=(|W1-W1'|/W1×100)) from the width W1 (W2) of the reference mark 20 to the width W1' (W2') of the transfer reference mark is preferably 10% or less. Also, , when the deviation ΔW is 1% or more, and further, when ΔW is 3% or more, the effect of the present invention can be more significantly obtained. The length L' of the transfer reference mark is, for example, 100 μm or more and 1500 μm or less. From the reference mark The deviation ΔL (=(|L-L'|/L×100) from the length L of 20 to the length L' of the transfer reference mark is preferably 1% or less. In addition, when the deviation ΔL is 0.05% or more In this case, the effect of the present invention can be obtained more significantly.

For example, when the reference mark 20 has a substantially circular shape, the transferred reference mark also has a substantially circular shape. The deviation (absolute value) from the diameter of the reference mark 20 to the diameter of the transfer reference mark is preferably 10% or less. In addition, when the deviation is 1% or more, and furthermore, when the deviation is 3% or more, the effect of the present invention can be obtained more significantly.

When the reference mark 20 is concave (convex), the transfer reference mark is also concave (convex). The depth D’ (height H’) of the transferred reference mark is preferably 30 nm or more. The depth D' (height H') is preferably 100 nm or less, more preferably 50 nm or less. The deviation ΔD (ΔH) from the depth D’ (height H’) of the reference mark 20 to the depth D’ (height H’) of the transferred reference mark is preferably 10% or less. In addition, when the deviation ΔD (ΔH) is 0.05% or more, and furthermore, when ΔD (ΔH) is 1% or more, the effect of the present invention can be obtained more significantly.

When the absorber film (laminated film 28) is provided with a transfer reference mark, the value of 3σ obtained in the following steps (1) to (5) may be less than 50 nm.

(1) Obtain the first defect coordinates of the defect in the multilayer reflective film substrate 10 and the first reference mark coordinates of the reference mark 20 through a defect inspection device having a first coordinate system.

(2) Obtain the second defect coordinates of the defect in the reflective mask substrate 30 and the second reference mark coordinates of the transfer reference mark by using a coordinate measuring device with a second coordinate system.

(3) Calculate a conversion coefficient for converting the coordinates from the first coordinate system of the defect inspection device to the second coordinate system of the coordinate measuring device based on the first reference mark coordinates and the second reference mark coordinates.

(4) Use the conversion coefficient calculated in the above (3) to convert the first defect coordinate obtained by the defect inspection device in the above (1) to the third defect based on the second coordinate system of the coordinate measuring machine. Coordinate conversion.

(5) Find the value of 3σ based on the difference between the second defect coordinate obtained by the coordinate measuring machine in the above (2) and the third defect coordinate converted in the above (4).

Although the above steps (1) to (5) are the same as the steps (1) to (5) in the multilayer reflective film substrate 10 of the first embodiment, in the step (2), a coordinate measuring device is used to measure The points to obtain the second defect coordinates of the defect in the reflective mask substrate 30 and the second reference mark coordinates of the transfer reference mark are different.

The inventor found that, as shown in Table 1 and FIG. 7 of Example 1 below, when the number of reference marks 20 is N, 3σ tends to be inversely proportional to N ^1/2 . That is, it is found that when the proportionality constant is α, the following formula is established.

3σ=α/N ^1/2 ...(1)

For example, the results shown in Table 1 can be applied to the above formula (1), and then the value of α can be obtained by the least squares method. α is a coefficient that varies depending on the device. In this case, α=70.

FIG. 8 shows a graph of the above-mentioned formula (1) with α=70.

From this chart, it can be seen that the greater the number of fiducial marks 20, the higher the defect coordinate conversion accuracy is. The number of fiducial marks 20 can be determined based on the desired 3σ. The number of reference marks 20 is preferably 4 or more so that 3σ can be less than 50 nm. In addition, the number of reference marks 20 is more preferably 8 or more, so that 3σ can be less than 25 nm. In addition, the number of reference marks 20 is preferably 16 or more, so that 3σ can be less than 20 nm. In addition, from the viewpoint of increasing the number of steps for forming the reference marks 20 and increasing defects when there are too many reference marks 20, the number of the reference marks 20 is preferably 100 or less. Furthermore, when the number of reference marks 20 exceeds 60, the reduction range of 3σ tends to decrease. Therefore, the number of reference marks 20 is preferably 60 or less.

In the reflective mask substrate 30 of this embodiment, the value of 3σ obtained through the above steps (1) to (5) is less than 50 nm. Preferably, the value of 3σ is less than 50 nm for both x-coordinate and y-coordinate data. By setting the value of 3σ to less than 50 nm, the conversion accuracy from the first coordinate system of the defect inspection device to the second coordinate system of the coordinate measuring device can be improved.

Thereby, the user who is provided with the reflective mask substrate 30 can compare the defect position and the drawing data specified by the defect inspection device with high accuracy, and can accurately determine the defects in the finally manufactured reflective mask. to reduce defects.

In the reflective mask substrate 30 of this embodiment, in the above-mentioned step (2), the coordinates of the second reference mark of the transfer reference mark transferred to the absorber film (laminated film 28) are obtained. When drawing a pattern on the resist film using an electronic line drawing device, the FM on the absorber film is used as a reference. Therefore, the second reference of the transfer reference mark transferred to the absorber film is used. Marking coordinates can further improve the accuracy of coordinate conversion. That is, when the absorber film (laminated film 28) is formed on the reference mark, the width and depth of the transferred reference mark transferred to the absorber film may change, which may cause the detected reference mark to be Location changes. By obtaining the coordinates of the second reference mark of the transferred reference mark transferred to the absorber film, and then calculating the conversion coefficient using the obtained coordinates of the second reference mark, the influence of the positional shift of the reference mark can be calculated. followed by the conversion coefficient. As a result, the coordinate conversion accuracy in the above-mentioned step (4) can be further improved.

(Fourth Embodiment)

The fourth embodiment is to obtain the corresponding relationship between the number of reference marks and 3σ by using other multi-layer reflective film substrates and other reflective mask substrates having laminated films on the other multi-layer reflective film substrates. The reflective mask base 30 is different from the third embodiment in that it has a number of reference marks determined based on the corresponding relationship. Other than that, everything is the same as the third embodiment.

That is, the reflective mask substrate 30 of this embodiment is provided with the reference mark 20 that serves as a positional reference for defects of the multilayer reflective film substrate 10 . The absorber film (laminated film 28) formed on the multilayer reflective film substrate 10 has a transferred reference mark having a shape in which the reference mark 20 is transferred. The number of the reference marks 20 is determined in advance through the following steps (1) to (7).

(1) Obtain the first defect coordinates of defects in other multi-layer reflective film substrates having plural reference marks and the first reference mark coordinates of the reference marks through a defect inspection device having a first coordinate system.

(2) Obtain and transfer the second defect coordinates of defects in other reflective mask substrates having laminated films formed on other multi-layer reflective film substrates using a coordinate measuring device having a second coordinate system The coordinates of the second datum mark of the datum mark.

(3) Calculate a conversion coefficient for converting coordinates from the first coordinate system to the second coordinate system based on the first reference mark coordinates and the second reference mark coordinates.

(4) Use the conversion coefficient calculated in the above (3) to convert the first defect coordinate obtained by the defect inspection device in the above (1) to the third defect coordinate based on the second coordinate system. Convert.

(5) Find the value of 3σ based on the difference between the second defect coordinate obtained by the coordinate measuring device in the above (2) and the third defect coordinate converted in the above (4).

(6) Obtain the corresponding relationship between the number of fiducial marks and 3σ.

(7) Determine the number of fiducial marks that have a desired value of 3σ (for example, less than 50 nm).

The above-mentioned steps (1) to (5) are the same as the steps (1) to (5) of the third embodiment, except that other substrates with multi-layer reflective films and other reflective mask substrates are used.

Other substrates with multilayer reflective films are the same as those in the third embodiment. Other reflective mask substrates have a plurality of transferred fiducial marks that are transferred to fiducial marks that would be formed on other substrates with multi-layer reflective films.

Since in this embodiment, other substrates with multi-layer reflective films and other reflective mask substrates are used to determine the number of fiducial marks, it can correspond to the shape of the fiducial marks, the shape of the transferred fiducial marks, the defect inspection device and or a coordinate measuring machine to obtain the multi-layer reflective film substrate 10 with an optimal number of reference marks 20 .

[Method of manufacturing reflective mask]

The reflective mask base 30 of this embodiment can be used to manufacture the reflective mask 40 of this embodiment. The manufacturing method of the reflective mask 40 will be described below.

FIG. 4 is a schematic diagram showing a method of manufacturing the reflective mask 40 .

As shown in FIG. 4 , first, a substrate 12 , a multilayer reflective film 14 formed on the substrate 12 , a protective film 18 formed on the multilayer reflective film 14 , and an absorber film (laminated film 28 ) formed on the protective film 18 are prepared. ) of the reflective mask substrate 30 (Fig. 4(a)). Next, the resist film 32 is formed on the absorber film (Fig. 4(b)). A pattern is drawn on the resist film 32 using an electron beam drawing device, and the resist pattern 21a is formed by further developing and rinsing processes (Fig. 4(c)).

The absorber film (laminated film 28) is dry-etched using the resist pattern 32a as a mask. Thereby, the portion of the absorber film that is not covered by the resist pattern 32a is etched to form the absorber film pattern 28a (Fig. 4(d)).

In addition, as the etching gas system, chlorine-based gases such as Cl ₂ , SiCl ₄ , CHCl ₃ , and CCl ₄ may be used. A mixed gas containing these chlorine-based gases and O ₂ at a predetermined ratio may be used. The mixed gas of gas and He contains a mixed gas of chlorine-based gas and Ar in a predetermined ratio, CF ₄ , CHF ₃ , C ₂ F ₆ , C ₃ F ₆ , C ₄ F ₆ , C ₄ F ₈ , CH ₂ F _2. Fluorine-based gases such as CH ₃ F, C ₃ F ₈ , SF ₆ and F, a mixed gas containing these fluorine-based gases and O ₂ in a predetermined ratio, and a mixture containing a fluorine-based gas and Ar in a predetermined ratio. Gas etc.

After the absorber film pattern 28a is formed, the resist pattern 32a is removed using, for example, a resist stripping liquid. After removing the resist pattern 32a, the reflective mask 40 of this embodiment is obtained by going through a wet cleaning process using an acidic or alkaline aqueous solution (FIG. 4(e)).

[Method for manufacturing semiconductor device]

The transfer pattern can be formed on the semiconductor substrate by lithography using the reflective mask 40 of this embodiment. This transfer pattern has a shape in which the absorber film pattern 28a of the reflective mask 40 is transferred. By using the reflective mask 40 to form a transfer pattern on the semiconductor substrate, a semiconductor device can be manufactured.

Using FIG. 5 , a method of transferring a pattern to a resist-containing semiconductor substrate 56 using EUV light will be described.

FIG. 5 shows the pattern transfer device 50. The pattern transfer device 50 includes a laser plasma X-ray source 52, a reflective mask 40, a reduction optical system 54, and the like. An X-ray mirror is used as the reduction optical system 54 .

The pattern reflected by the reflective mask 40 will be reduced to about 1/4 of the normal size by the reduction optical system 54 . For example, a 13~14nm wavelength band is used as the exposure wavelength, and the light path is preset so that it falls in a vacuum. Under such conditions, the EUV light generated by the laser plasma X-ray source 52 will be incident on the reflective mask 40 . The light reflected by the reflective mask 40 is transferred to the resist semiconductor substrate 56 through the reduction optical system 54 .

The light incident on the reflective mask 40 will be absorbed by the absorber film at the portion with the absorber film pattern 28a and will not be reflected. On the other hand, the light incident on the portion without the absorber film pattern 28 a will be reflected by the multilayer reflective film 14 .

The light reflected by the reflective mask 40 will be incident on the reduction optical system 54 . The light incident on the reduction optical system 54 will form a transfer pattern on the resist layer on the resist semiconductor substrate 56 . By developing the exposed resist layer, a resist pattern can be formed on the resist-containing semiconductor substrate 56 . By etching the semiconductor substrate 56 using the resist pattern as a mask, for example, a predetermined wiring pattern can be formed on the semiconductor substrate. A semiconductor device is manufactured by going through such processes and other necessary processes.

In the case where the reference mark formed on the substrate with a multi-layer reflective film is FM, the number of FMs in the reflective mask substrate of this embodiment can be determined by, for example, the above-mentioned second embodiment or fourth embodiment, and then It is produced by the following method.

A method for manufacturing a reflective mask substrate, which includes: A process of forming a multi-layer reflective film on a substrate to form a substrate with a multi-layer reflective film; a process of forming a number of FMs determined based on a desired 3σ on the surface of the substrate with a multi-layer reflective film; by using a defect inspection device , the process of obtaining the first defect coordinates of the defect on the surface of the multilayer reflective film substrate and the first FM coordinate of the FM to obtain a defect map based on the first FM coordinate and displaying the first defect coordinate; and in the tool A process of forming a laminated film having the FM transferred thereon on a multilayer reflective film substrate.

Users who are provided with the above-mentioned reflective mask substrate and defect map can accurately compare the defect positions and drawing data specified by the defect inspection device based on the transfer FM, and can finally create the reflective Defects are reliably reduced in type masks.

In the case where the reference marks formed on the substrate with a multi-layer reflective film are AM, the number of AMs in the reflective mask substrate of this embodiment can be determined by, for example, the above-mentioned second embodiment or fourth embodiment, and then It is produced by the following method.

A method for manufacturing a reflective mask substrate, which includes the following steps: forming a multi-layer reflective film on a substrate to form a substrate with a multi-layer reflective film; forming a multi-layer reflective film substrate on the surface determined based on a desired 3σ The process of obtaining the number of AM by using a defect inspection device to obtain the first defect coordinate of the defect on the surface of the multi-layer reflective film substrate and the 1AM coordinate of the AM, so as to obtain the 1st AM coordinate as the basis and display the 1st AM coordinate. 1. The process of generating the first defect map of defect coordinates; the process of forming a laminated film having the AM transferred thereon on the multilayer reflective film substrate; and the process of forming FM on the surface of the laminated film. ;as well as By using a coordinate measuring machine to obtain the 2nd AM coordinates of the transfer AM and the FM coordinates of the FM, the first defect map is converted into a second defect map based on the FM coordinates and displaying the first defect coordinates. .

The user who is provided with the above-mentioned reflective mask base and the second defect map can highly accurately compare the defect position and drawing data specified by the defect inspection device based on FM, and can finally produce the reflective Defects are reliably reduced in type masks.

[Example]

Below, further specific embodiments of the present invention will be described.

<Example 1>

Prepare a SiO ₂ -TiO ₂ glass substrate (6 inches square, 6.35mm thick). The end surface of the glass substrate was chamfered and ground, and further roughened with a polishing liquid containing cerium oxide abrasive grains. The processed glass substrate is placed on the carrier of the double-sided polishing device, and an alkaline aqueous solution containing silica gel abrasive particles is used in the polishing liquid, and precision polishing is performed under predetermined polishing conditions. After the precision grinding is completed, the glass substrate is cleaned. The surface roughness of the main surface of the obtained glass substrate was root mean square roughness (RMS) of 0.10 nm or less. The flatness of the main surface of the obtained glass substrate was 30 nm or less in the measurement area of 132 mm×132 mm.

An inner surface conductive film composed of CrN was formed on the inner surface of the glass substrate by pulse magnetron sputtering under the following conditions.

(Conditions): Cr target, Ar+N ₂ gas atmosphere (Ar: N ₂ =90%: 10%), film composition (Cr: 90 atomic %, N: 10 atomic %), film thickness 20 nm.

A multilayer reflective film is formed by periodically stacking Mo film/Si film on the main surface of the glass substrate opposite to the side where the inner surface conductive film is formed.

Specifically, Mo target material and Si target material are used, and Mo film and Si film are alternately laminated on the substrate by ion beam sputtering (using Ar). The thickness of the Mo film is 2.8nm. The thickness of the Si film is 4.2nm. The thickness of one cycle of Mo/Si film is 7.0nm. This Mo/Si film is laminated for 40 cycles, and finally a Si film is formed with a film thickness of 4.0 nm to form a multilayer reflective film.

A protective film containing a Ru compound is formed on the multilayer reflective film. Specifically, RuNb target material (Ru: 80 atomic %, Nb: 20 atomic %) is used to form a RuNb film on a multi-layer reflective film by DC pulse magnetron sputtering in an Ar gas atmosphere. Protective film. The thickness of the protective film is 2.5nm.

FM is formed on the protective film by laser processing.

The conditions for laser processing are as follows.

Laser type: semiconductor laser with wavelength 405nm

Laser output: 20mW (continuous wave)

Spot size: 430nmφ

The shape and dimensions of FM are as follows.

Shape: Slightly cross-shaped

Depth D: 40nm

Width W1, W2: 1μm

Length L: 1mm

There are 8 FM departments.

The formation position of FM is shown in Figure 6, which is outside the effective area of 132mm×132mm (the area shown by the dotted line).

The first defect coordinate and the first FM coordinate of the defect in the multilayer reflective film substrate were obtained using a defect inspection device (Lasertec Co., Ltd., ABI). The number of defects is 4.

An absorber film is formed on the protective film of the multi-layer reflective film substrate to produce a reflective mask substrate. Specifically, an absorber film composed of a laminated film of TaBN (thickness 56 nm) and TaBO (thickness 14 nm) was formed by DC pulse magnetron sputtering. The TaBN film is formed by reactive sputtering in a mixed gas atmosphere of Ar gas and N ₂ gas using a TaB target. TaBO is formed by reactive sputtering in a mixed gas atmosphere of Ar gas and O ₂ gas using TaB target material. The laminated film system forms transfer FM onto which FM is transferred.

A coordinate measuring machine (LMS-IPRO4 manufactured by KLA-Tencor) was used to obtain the second defect coordinates of the defects in the reflective mask substrate and the second FM coordinates of the transfer FM.

Using the acquired 1st FM coordinate and 2nd FM coordinate, the conversion coefficient for coordinate conversion from the 1st coordinate system of a defect inspection apparatus to the 2nd coordinate system of a coordinate measuring device is calculated. The conversion coefficient is calculated using the above affine conversion formula.

The calculated conversion coefficient is used to convert the first defect coordinate obtained by the defect inspection device to the second coordinate system of the coordinate measuring device to obtain the third defect coordinate.

The difference between the third defect coordinate obtained by conversion and the second defect coordinate obtained by the coordinate measuring machine is obtained for the X coordinate and Y coordinate respectively. This "difference" (absolute value) is calculated for all defect data, and then the standard deviation σ and 3σ are calculated based on this "difference". As a result, when there are 8 FMs, the X coordinate of the 3σ system is 24.2 nm and the Y coordinate is 23.3 nm, both of which are less than 50 nm.

Also, let the number of FMs change between 3 and 7, and then calculate the value of 3σ in the same manner as in the case where the number of FMs is 8. The calculation results of 3σ when the number of FMs is 3 to 8 are shown in Table 1 below and the graph in Figure 7.

[Table 1]

As shown in Table 1 and Figure 7, when the number of FMs is 4 or more, 3σ does not reach 50nm in both the The conversion accuracy of the coordinate system will be higher.

A resist film is formed on the absorber film of the reflective mask base manufactured above. An electronic line drawing device is used to draw a pattern on the resist film. When drawing patterns, 4 transfer FMs are used as the basis for defect coordinates. After drawing the pattern, a predetermined development process is performed to form a resist pattern on the absorber film.

The resist pattern is used as a mask to form a pattern on the absorber film. Specifically, after the upper TaBO film is dry-etched with a fluorine-based gas (CF ₄ gas), the lower TaBN film is dry-etched with a chlorine-based gas (Cl ₂ gas).

By using hot sulfuric acid to remove the resist pattern remaining on the absorber film pattern, the reflective mask related to Example 1 can be obtained. When the EUV reflective mask thus obtained was inspected with a mask defect inspection device (Teron 600 series manufactured by KLA-Tencor), no defects were confirmed in the exposed area of the multilayer reflective film of the absorber film pattern.

<Example 2>

Except that the number of FMs was changed from 8 to 16, a substrate with a multilayer reflective film and a reflective mask substrate were manufactured in the same manner as in Example 1 above.

The formation position of FM is shown in Figure 9, which is outside the effective area of 132mm×132mm (the area shown by the dotted line).

3σ was calculated in the same manner as in Example 1. As a result, when there are 16 FMs, the X coordinate of the 3σ system is 18.2 nm and the Y coordinate is 18.0 nm, both of which are less than 50 nm.

In the same manner as Example 1, based on the position information of the defect based on the transfer FM, a pattern is drawn on the resist film using an electronic line drawing device to obtain the reflective mask of Example 2. When the EUV reflective mask thus obtained was inspected with a mask defect inspection device (Teron 600 series manufactured by KLA-Tencor), no defects were confirmed in the exposed area of the multilayer reflective film of the absorber film pattern.

<Example 3>

The multi-layer reflective film substrate and reflective mask substrate with 8 FMs formed in Example 1 are used as other multi-layer reflective film substrates and other reflective mask substrates to produce the multi-layer reflective film substrate of Example 3 and Reflective mask base.

From the corresponding relationship between the number of FMs and 3σ obtained in Example 1, it was calculated that 3σ is the number of FMs less than 30 nm, and the number of FMs is 7.

Similar to Example 1, a multilayer reflective film and a protective film were formed on the main surface of the glass substrate opposite to the side where the inner conductive film is formed. FM is formed on the protective film through laser processing to produce a multi-layer reflective film substrate with 7 FMs.

The shape and dimensions of FM are as follows.

Shape: Slightly cross-shaped

Depth D: 40nm

Width W1, W2: 1μm

Length L: 1m

As in Example 1, a defect inspection device (Lasertec Co., Ltd., ABI) was used to obtain the first defect coordinates and the first FM coordinates of the defects in the multilayer reflective film substrate, thereby obtaining a relative representation of the first defect coordinates. Defect map at 1FM coordinates. The number of defects is 5.

In the same manner as in Example 1, a laminated film on which transfer FM is formed is formed on the protective film to produce a reflective mask base. The offset ΔD from the depth D of the FM to the depth D' of the transferred FM is almost zero. The offsets ΔW1 and ΔW2 from the widths W1 and W2 of the FM to the widths W1’ and W2’ of the transferred FM are 7% respectively. The offset ΔL from the length L of the FM to the length L’ of the transferred FM is 0.1%.

A coordinate measuring machine (LMS-IPRO4 manufactured by KLA-Tencor) was used to obtain the second defect coordinates of the defects in the reflective mask substrate and the second FM coordinates of the transfer FM. As in Embodiment 1, the first defect coordinates are converted into the second coordinate system of the coordinate measuring device, and then the third defect coordinates obtained by the conversion and the coordinate measuring device are obtained for the X coordinate and Y coordinate respectively. The difference between the obtained coordinates of the second flaw. As a result, the 3σ system satisfies the requirement of less than 30 nm.

Using the reflective mask base manufactured above, a reflective mask was manufactured in the same manner as in Example 1. When the EUV reflective mask thus obtained was inspected with a mask defect inspection device (Teron 600 series manufactured by KLA-Tencor), no defects were confirmed in the exposed area of the multilayer reflective film of the absorber film pattern.

<Example 4>

Based on the results in Figure 8 above, 28 were calculated as the number of AMs with 3σ less than 20 nm, and the multi-layer reflective film substrate and reflective mask substrate of Example 4 were produced.

Similar to Example 1, a multilayer reflective film and a protective film are formed on the main surface of the glass substrate opposite to the side where the inner conductive film is formed.

AM is formed on the protective film by laser processing.

The conditions for laser processing are as follows.

Laser type: semiconductor laser with wavelength 405nm

Laser output: 20mW (continuous wave)

Spot size: 430nmφ

The shape and size of AM are as follows.

Shape: slightly round

Depth: 40nm

Diameter: 0.9μm

There are 28 AM systems formed.

The formation position of AM is shown in Figure 10, which is outside the effective area of 132mm×132mm (the area shown by the dotted line).

A defect inspection device (Lasertec Co., Ltd., ABI) was used to obtain the first defect coordinates and the first AM coordinates of 28 AM of the defects in the multilayer reflective film substrate.

An absorber film is formed on the protective film of the multi-layer reflective film substrate to produce a reflective mask substrate. Specifically, an absorber film composed of a laminated film of TaBN (thickness 56 nm) and TaBO (thickness 14 nm) was formed by DC pulse magnetron sputtering. The TaBN film is formed by reactive sputtering in a mixed gas atmosphere of Ar gas and N ₂ gas using a TaB target. The TaBO film is formed by reactive sputtering in a mixed gas atmosphere of Ar gas and O ₂ gas using a TaB target. The absorber film (laminated film) is composed of 28 transferred AMs onto which AM is transferred. The offset ΔD from the depth D of the AM to the depth D' of the transferred AM is almost zero. The offset from the diameter of the AM to the diameter of the transferred AM is 6%.

FM is formed on the surface of the absorber film by FIB processing.

The FIB processing conditions are as follows.

Acceleration voltage: 50kV

Ion beam current value: 20pA

The shape and dimensions of FM are as follows.

Shape: Slightly cross-shaped

Depth D: 70nm

Width W1, W2: 5μm

Length L: 1mm

There are 4 FM systems.

The formation position of FM is shown in Figure 10, which is outside the effective area of 132mm×132mm (the area shown by the dotted line).

A coordinate measuring machine (LMS-IPRO4 manufactured by KLA-Tencor) was used to obtain the second defect coordinates of the defect in the reflective mask substrate and the second AM coordinates of the 28 transfer AMs.

The conversion coefficient for coordinate conversion from the first coordinate system of the defect inspection device to the second coordinate system of the coordinate measuring device is calculated using the first AM coordinate of the obtained AM and the second AM coordinate of the transferred AM. The conversion coefficient is calculated using the above affine conversion formula.

The calculated conversion coefficient is used to convert the first defect coordinate obtained by the defect inspection device to the second coordinate system of the coordinate measuring device to obtain the third defect coordinate.

The difference between the third defect coordinate obtained by conversion and the second defect coordinate obtained by the coordinate measuring machine is obtained for the X coordinate and Y coordinate respectively. This "difference" (absolute value) is calculated for all defect data, and then the standard deviation σ and 3σ are calculated based on this "difference". As a result, when the number of AMs is 28, the X coordinate of the 3σ system is 14.9 nm and the Y coordinate is 14.1 nm, both of which are less than 50 nm.

A resist film is formed on the absorber film of the reflective mask base manufactured above. An electronic line drawing device is used to draw a pattern on the resist film. When drawing patterns, FM is used as the basis for defect coordinates. Specifically, a coordinate measuring device is used to obtain the relative positional relationship between the transferred AM and FM. This positional relationship is used to convert the positional information of the defect based on AM into the positional information of the defect based on FM. Based on the position information of the defect based on FM, an electronic line drawing device is used to draw a pattern on the resist film.

The resist pattern is used as a mask to form a pattern on the absorber film. Specifically, after the upper TaBO film is dry-etched with a fluorine-based gas (CF ₄ gas), the lower TaBN film is dry-etched with a chlorine-based gas (Cl ₂ gas).

By using hot sulfuric acid to remove the resist pattern remaining on the absorber film pattern, the reflective mask related to Embodiment 4 can be obtained. When the EUV reflective mask thus obtained was inspected with a mask defect inspection device (Teron 600 series manufactured by KLA-Tencor), no defects were confirmed in the exposed area of the multilayer reflective film of the absorber film pattern.

<Comparative example 1>

Except that the number of FMs was changed from 8 to 3, a substrate with a multilayer reflective film and a reflective mask substrate were manufactured in the same manner as in Example 1 above.

The formation position of FM is shown in Figure 11, which is outside the effective area of 132mm×132mm (the area shown by the dotted line).

3σ was calculated in the same manner as in Example 1. As a result, when there are three FMs, the X coordinate of the 3σ system is 62.7 nm and the Y coordinate is 57.3 nm, both of which are 50 nm or more.

Similar to Example 1, based on the position information of the defect based on the transfer FM, a pattern was drawn on the resist film using an electronic line drawing device to obtain the reflective mask of Comparative Example 1. When the EUV reflective mask thus obtained was inspected with a mask defect inspection device (Teron 600 series manufactured by KLA-Tencor), the defects could not be hidden under the absorber film pattern due to poor coordinate conversion accuracy. Defects were confirmed in the exposed areas of the multi-layer reflective film.

10:Substrate with multi-layer reflective film

12:Substrate

14:Multilayer reflective film

18:Protective film

Claims (10)

A substrate with a multi-layer reflective film, which has a substrate and a multi-layer reflective film that is formed on the substrate and reflects EUV light; Having fiducial marks that serve as positional references for defects in the multi-layer reflective film substrate; The number of the fiducial marks is the number obtained in advance through the following steps (1)~(7); (1) Obtain the first defect coordinates of defects in other multi-layer reflective film substrates with plural reference marks and the first reference mark coordinates of the reference marks through a defect inspection device having a first coordinate system; (2) Obtain the second defect coordinates of the defect in the other substrate with a multi-layer reflective film and the second fiducial mark coordinates of the fiducial mark by using a coordinate measuring instrument with a second coordinate system; (3) Calculate the conversion coefficient for converting from the first coordinate system to the second coordinate system based on the first reference mark coordinates and the second reference mark coordinates; (4) Use the conversion coefficient calculated in (3) to convert the first defect coordinate obtained by the defect inspection device in the above (1) to the third defect coordinate based on the second coordinate system. ; (5) Find the value of 3σ based on the difference between the second defect coordinate obtained by the coordinate measuring device in the above (2) and the third defect coordinate converted in the above (4); (6) Obtain the corresponding relationship between the number of fiducial marks and 3σ; and (7) The value of 3σ will determine the number of fiducial marks less than 50nm. For example, for the substrate with a multi-layer reflective film in Item 1 of the patent application, the number of the fiducial marks is more than 8. For example, for the substrate with a multi-layer reflective film in Item 1 of the patent application, the number of the fiducial marks is more than 16. A reflective mask substrate has: a substrate with a multi-layer reflective film as in any one of items 1 to 3 of the patent application scope; and a laminated film formed on the substrate with a multi-layer reflective film. A reflective mask substrate has: a multi-layer reflective film substrate having a substrate and a multi-layer reflective film formed on the substrate and reflecting EUV light; and a laminated film formed on the multi-layer reflective film substrate ; The substrate with a multi-layer reflective film is provided with a reference mark that serves as a position reference for defects in the substrate with a multi-layer reflective film; The laminated film is provided with a transfer reference mark on which the reference mark is transferred; The number of the fiducial marks is the number obtained in advance through the following steps (1)~(7); (1) Obtain the first defect coordinates of defects in other multi-layer reflective film substrates with plural reference marks and the first reference mark coordinates of the reference marks through a defect inspection device having a first coordinate system; (2) Obtain the second defect coordinates and transfer reference of the defect in the reflective mask substrate having the laminated film formed on the other multi-layer reflective film substrate by using a coordinate measuring device with the second coordinate system The coordinates of the second datum mark of the mark; (3) Calculate the conversion coefficient for converting from the first coordinate system to the second coordinate system based on the first reference mark coordinates and the second reference mark coordinates; (4) Use the conversion coefficient calculated in (3) to convert the first defect coordinate obtained by the defect inspection device in the above (1) to the third defect coordinate based on the second coordinate system. ; (5) Find the value of 3σ based on the difference between the second defect coordinate obtained by the coordinate measuring device in the above (2) and the third defect coordinate converted in the above (4); (6) Obtain the corresponding relationship between the number of fiducial marks and 3σ; and (7) The value of 3σ will determine the number of fiducial marks less than 50nm. For example, in the reflective mask substrate of Item 5 of the patent application, the number of the fiducial marks is more than 8. For example, in the reflective mask substrate of Item 5 of the patent application, the number of the fiducial marks is more than 16. For example, the reflective mask substrate according to any one of items 5 to 7 of the patent application, wherein the laminated film includes an absorber film that absorbs EUV light. A method for manufacturing a reflective mask includes the step of forming a laminated film pattern on the laminated film in the reflective mask base as claimed in Item 4 or 8 of the patent application. A method of manufacturing a semiconductor device includes a step of forming a transfer pattern on a semiconductor substrate using a reflective mask manufactured by the reflective mask manufacturing method of Claim 9 of the patent application.

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