JPWO2020095959A1 - Substrate with multi-layer reflective film, reflective mask blank, reflective mask manufacturing method, and semiconductor device manufacturing method - Google Patents

Abstract

The conversion accuracy from the coordinate system of the defect inspection device for detecting defects on the multilayer reflective film to the coordinate system of other devices is improved. The substrate with the multilayer reflective film has the number of reference marks previously determined by the procedures (1) to (7). (1) The defect inspection device acquires the first defect coordinates of the defect in another substrate with a multilayer reflective film and the first reference mark coordinates of the reference mark. (2) The coordinate measuring instrument acquires the second defect coordinates of the defect in another substrate with a multilayer reflective film and the second reference mark coordinates of the reference mark. (3) Based on the first reference mark coordinates and the second reference mark coordinates, the conversion coefficient for converting the coordinates from the coordinate system of the defect inspection device to the coordinate system of the coordinate measuring instrument is calculated. (4) Using the conversion coefficient calculated in (3), the first defect coordinates are converted into the third defect coordinates. (5) The value of 3σ is obtained for the difference between the second defect coordinates and the third defect coordinates. (6) Acquire the correspondence between the number of reference marks and 3σ. (7) Determine the number of reference marks whose value of 3σ is less than 50 nm.

Description

The present invention relates to a substrate with a multilayer reflective film, a reflective mask blank, a method for manufacturing a reflective mask, and a method for manufacturing a semiconductor device.

With the recent demand for higher density and higher precision of VLSI devices, EUV lithography, which is an exposure technique using extreme ultraviolet (hereinafter referred to as EUV) light, is expected to be promising. Here, EUV light refers to light in the wavelength band of the soft X-ray region or the vacuum ultraviolet region, and specifically, light having a wavelength of about 0.2 to 100 nm. A reflective mask has been proposed as a mask used in EUV lithography. In the reflective mask, a multilayer reflective film that reflects exposure light is formed on a substrate such as glass or silicon, and an absorber film pattern that absorbs exposure light is formed on the multilayer reflective film. In the exposure machine that performs pattern transfer, the light incident on the reflective mask mounted on the exposure machine is absorbed by the portion having the absorber film pattern and reflected by the multilayer reflective film in the portion without the absorber film pattern. Then, the reflected light image is transferred onto a semiconductor substrate such as a silicon wafer via the reflection optical system.

As the demand for miniaturization in the lithography process increases, the problems in the lithography process are becoming more prominent. One of the problems is a problem related to defect information of a mask blank substrate or the like used in a lithography process.

Conventionally, in blank inspection or the like, the existing position of a defect on a substrate is specified by a distance from the origin using a coordinate system managed by a defect inspection apparatus with the center of the substrate as the origin (0,0). For this reason, the standard of absolute value coordinates is not clear, the position accuracy is low, and the detection varies between devices. Further, even when patterning on a thin film for pattern formation while avoiding defects at the time of pattern drawing, it is difficult to avoid defects on the order of μm. For this reason, defects have been avoided by changing the transfer direction of the pattern or roughly shifting the transfer position on the order of mm.

Under such circumstances, it has been proposed to form a reference mark on, for example, a mask blank substrate, and to specify the position of a defect with reference to the reference mark. By forming the reference mark on the mask blank substrate, it is possible to prevent the reference for identifying the position of the defect from being deviated for each device.

In a reflective mask that uses EUV light as the exposure light, it is particularly important to accurately locate defects on the multilayer reflective film. This is because the defects present in the multilayer reflective film are almost impossible to correct and can be serious topological defects on the transfer pattern.

In order to accurately identify the position of a defect on the multilayer reflective film, it is preferable to acquire the position information of the defect by performing a defect inspection after forming the multilayer reflective film. For that purpose, it is preferable to form a reference mark on the multilayer reflective film formed on the substrate.

Patent Document 1 describes that a substrate for a reflective mask blank for EUV lithography and the like has a size of at least 30 to 100 nm in a sphere-equivalent diameter so that the position of a minute defect having a sphere-equivalent diameter of about 30 nm can be accurately identified. It is disclosed to form three marks.

International release WO2008 / 129914

Based on the defect data of the mask blank and the device pattern data, there is a technique (Defective mitigation technology) that corrects the drawing data so that the absorber film pattern is formed at the location where the defect exists to reduce the defect. Proposed. In order to realize such a technique, for example, in a reflective mask blank in which an absorber film is formed on a multilayer reflective film, a pattern is formed on a resist film formed on the absorber film by using an electron beam drawing machine. At the time of drawing, the electron beam drawing machine also detects the reference mark with the electron beam, and draws the pattern based on the corrected / corrected drawing data based on the detected reference point.

The coordinate system of the defect inspection device for acquiring the defect data of the mask blank is different from the coordinate system of the electron beam writer. Therefore, when drawing an electron beam using the reference mark and defect data acquired by the defect inspection device, it is necessary to convert the data into the coordinate system of the electron beam writer.

However, if the conversion accuracy from the coordinate system of the defect inspection device to the coordinate system of the electron beam drawing machine is poor, it is not possible to correct / correct the drawing data with high accuracy when the above-mentioned Defect mitigation technology is performed. Problems arise.

Therefore, the present invention provides a substrate with a multilayer reflective film and a reflective mask blank, which can improve the conversion accuracy from the coordinate system of a defect inspection device for detecting 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 conducted diligent research on improving the conversion accuracy from the coordinate system of the defect inspection device for detecting defects on the multilayer reflective film to the coordinate system of other devices. As a result, it was found that there is a correlation between the number of reference marks that serve as a reference for the defect position and the coordinate conversion accuracy, and the present invention has been completed.

In order to solve the above problems, the present invention has the following configurations.
(Structure 1)
A substrate with a multilayer reflective film having a substrate and a multilayer reflective film formed on the substrate that reflects EUV light.
It is provided with a reference mark that serves as a reference for the position of defects in the substrate with a multilayer reflective film.
A substrate with a multilayer reflective film, wherein the number of reference marks is the number obtained in advance by the following procedures (1) to (7).
(1) The defect inspection device having the first coordinate system acquires the first defect coordinates of the defect in another substrate with a multilayer reflective film having a plurality of reference marks and the first reference mark coordinates of the reference mark. do.
(2) The coordinate measuring instrument having the second coordinate system acquires the second defect coordinates of the defect and the second reference mark coordinates of the reference mark in the substrate with the other multilayer reflective film.
(3) Based on the first reference mark coordinates and the second reference mark coordinates, a conversion coefficient for converting the coordinates from the first coordinate system to the second coordinate system is calculated.
(4) Using the conversion coefficient calculated in (3) above, the first defect coordinates acquired by the defect inspection apparatus in (1) above are used as a third reference to the second coordinate system. Convert to defect coordinates of.
(5) The value of 3σ is obtained for the difference between the second defect coordinate acquired by the coordinate measuring instrument in the above (2) and the third defect coordinate converted in the above (4).
(6) Acquire the correspondence between the number of reference marks and 3σ.
(7) Determine the number of reference marks whose value of 3σ is less than 50 nm.

(Structure 2)
The substrate with a multilayer reflective film according to the configuration 1, wherein the number of the reference marks is 8 or more.

(Structure 3)
The substrate with a multilayer reflective film according to the configuration 1 or 2, wherein the number of the reference marks is 16 or more.

(Structure 4)
A reflective mask blank having a substrate with a multilayer reflective film according to any one of configurations 1 to 3 and a laminated film formed on the substrate with a multilayer reflective film.

(Structure 5)
A reflective mask blank having a substrate, a substrate with a multilayer reflective film having a multilayer reflective film for reflecting EUV light formed on the substrate, and a laminated film formed on the substrate with a multilayer reflective film.
The multi-layer reflective film-equipped substrate has a reference mark that serves as a reference for the position of defects in the multi-layer reflective film-equipped substrate.
The laminated film includes a transfer reference mark to which the reference mark is transferred.
A reflective mask blank, characterized in that the number of reference marks is the number obtained in advance by the following procedures (1) to (7).
(1) The defect inspection device having the first coordinate system acquires the first defect coordinates of the defect in another substrate with a multilayer reflective film having a plurality of reference marks and the first reference mark coordinates of the reference mark. do.
(2) The second defect coordinates of the defect in the reflective mask blank having the laminated film formed on the substrate with the other multilayer reflective film by the coordinate measuring instrument having the second coordinate system, and the transfer reference mark. Acquires the second reference mark coordinates of.
(3) Based on the first reference mark coordinates and the second reference mark coordinates, a conversion coefficient for converting the coordinates from the first coordinate system to the second coordinate system is calculated.
(4) Using the conversion coefficient calculated in (3) above, the first defect coordinates acquired by the defect inspection apparatus in (1) above are used as a third reference to the second coordinate system. Convert to defect coordinates of.
(5) The value of 3σ is obtained for the difference between the second defect coordinate acquired by the coordinate measuring instrument in the above (2) and the third defect coordinate converted in the above (4).
(6) Acquire the correspondence between the number of reference marks and 3σ.
(7) Determine the number of reference marks whose value of 3σ is less than 50 nm.

(Structure 6)
The reflective mask blank according to the configuration 5, wherein the number of the reference marks is 8 or more.

(Structure 7)
The reflective mask blank according to the configuration 5 or 6, wherein the number of the reference marks is 16 or more.

(Structure 8)
The reflective mask blank according to any one of configurations 4 to 7, wherein the laminated film includes an absorber film that absorbs EUV light.

(Structure 9)
A method for manufacturing a reflective mask, comprising a step of forming a laminated film pattern on the laminated film in the reflective mask blank according to the fourth or eighth aspect.

(Structure 10)
A method for manufacturing a semiconductor device, comprising a step of forming a transfer pattern on a semiconductor substrate using the reflective mask manufactured by the method for manufacturing a reflective mask according to the configuration 9.

According to the present invention, a substrate with a multilayer reflective film and a reflective type capable of improving the conversion accuracy from the coordinate system of a defect inspection device for detecting defects on a multilayer reflective film to the coordinate system of other devices. A mask blank can be provided. Further, according to the present invention, a method for manufacturing a reflective mask in which defects are reduced by using these substrates with a multilayer reflective film or a reflective mask blank and correcting drawing data based on these defect information and A method for manufacturing a semiconductor device can be provided.

It is a schematic diagram which shows the cross section of the substrate with a multilayer reflective film. It is a top view of the substrate with a multilayer reflective film, and is the enlarged view of the reference mark. It is a schematic diagram which shows the cross section of the reflective mask blank. It is a schematic diagram which shows the manufacturing method of a reflective mask. The pattern transfer device is shown. The location where FM is formed when the number of FM is eight is shown. It is a graph which shows the value of 3σ when the number of FM is 3-8. It is a graph which shows the calculation result of 3σ when the number N of a reference mark is increased to 200. The location where FM is formed when the number of FM is 16 is shown. The formation locations of AM and FM when the number of AM is 28 and the number of FM is 4. The location where FM is formed when the number of FM is three is shown.

(First Embodiment)
Hereinafter, embodiments of the present invention will be described in detail.
[Substrate with multilayer reflective film]
FIG. 1 is a schematic view showing a cross section of the substrate with a multilayer reflective film of the present embodiment.
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 which is exposure light. Further, the substrate 10 with a multilayer reflective film may be provided with a protective film 18 for protecting the multilayer reflective film 14. In the present embodiment, the multilayer reflective film 14 is formed on the substrate 12, and the protective film 18 is formed on the multilayer reflective film 14. As will be described later, the substrate 10 with the multilayer reflective film has four or more reference marks that serve as a reference for the defect position.

In addition, in this specification, "on" of a substrate or a film includes not only the case where it comes into contact with the upper surface of the substrate or film, but also the case where it does not come into contact with the upper surface of the substrate or film. That is, the term "above" the substrate or film includes the case where a new film is formed above the substrate or film, the case where another film is interposed between the substrate or film, and the like. .. Further, "on" does not necessarily mean the upper side in the vertical direction. "On" merely indicates the relative positional relationship between the substrate and the film.

<Board>
In the case of EUV exposure, the substrate 12 used for the substrate 10 with the multilayer reflective film of the present embodiment has a low heat within the range of 0 ± 5 ppb / ° C in order to prevent distortion of the absorber film pattern due to heat during exposure. Those having an expansion coefficient are preferably used. As a material having a low coefficient of thermal expansion in this range, for example, SiO _2- TiO _2- based glass, multi-component glass ceramics, or the like can be used.

It is preferable that the main surface on the side where the transfer pattern of the substrate 12 (the absorber film pattern described later corresponds to this) is formed is processed in order to increase the flatness. By increasing 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, the flatness is preferably 0.1 μm or less, more preferably 0.05 μm or less, and particularly preferably 0.05 μm or less in the region of 132 mm × 132 mm on the main surface on the side where the transfer pattern of the substrate 12 is formed. It is preferably 0.03 μm or less. The main surface on the side opposite to the side on which the transfer pattern is formed is a surface fixed to the exposure apparatus by an electrostatic chuck, and the flatness is 1 μm or less, more preferably 0 in the 142 mm × 142 mm region. It is 5.5 μm or less, particularly preferably 0.03 μm or less. In the present specification, the flatness is a value representing the warp (deformation amount) of the surface indicated by TIR (Total Indicated Reading), and the plane defined by the minimum square method with respect to the substrate surface is defined as the focal plane. It is the absolute value of the height difference between the highest position of the substrate surface above the 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 substrate 12 on the side where the transfer pattern is formed is preferably 0.1 nm or less in terms of root mean square roughness (RMS). The surface roughness can be measured with an atomic force microscope.

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

<Multilayer reflective film>
The substrate 10 with a multilayer reflective film includes a substrate 12 and a multilayer reflective film 14 formed on the substrate 12. The multilayer reflective film 14 is composed of, for example, a multilayer film in which elements having different refractive indexes are periodically laminated. The multilayer reflective film 14 has a function of reflecting EUV light.

Generally, the multilayer reflective film 14 includes a thin film of a light element or a compound thereof (a high refractive index layer) which is a high refractive index material and a thin film of a heavy element or a compound thereof (a low refractive index layer) which is a low refractive index material. ) And are alternately laminated for about 40 to 60 cycles.
In order to form the multilayer reflective film 14, the high refractive index layer and the low refractive index layer may be laminated in this order for a plurality of cycles from the substrate 12 side. In this case, the laminated structure of one (high refractive index layer / low refractive index layer) has one cycle.
In order to form the multilayer reflective film 14, the low refractive index layer and the high refractive index layer may be laminated in this order for a plurality of cycles from the substrate 12 side. In this case, the laminated structure of one (low refractive index layer / high refractive index layer) has one cycle.

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 laminated in this order from the substrate 12 side, the uppermost layer becomes the low refractive index layer. However, when the low refractive index layer is the surface of the multilayer reflective film 14, the low refractive index layer is easily oxidized and the reflectance of the multilayer reflective film is reduced, so that the low refractive index layer is placed on the low refractive index layer. Form a high refractive index layer. On the other hand, when the low refractive index layer and the high refractive index layer are laminated in this order from the substrate 12 side, the uppermost layer becomes the high refractive index layer. In that case, the uppermost high-refractive index layer becomes the surface of the multilayer reflective film 14.

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

In the present embodiment, the low refractive index material is at least one element selected from the group consisting of Mo, Ru, Rh, and Pt, or at least selected from the group consisting of Mo, Ru, Rh, and Pt. Alloys containing one element can be used.

For example, as the multilayer reflective film 14 for EUV light having a wavelength of 13 to 14 nm, a Mo / Si multilayer film in which Mo films and Si films are alternately laminated for about 40 to 60 cycles can be preferably used. In addition, as the multilayer reflective film used in the region of EUV light, for example, Ru / Si periodic multilayer film, Mo / Be periodic multilayer film, Mo compound / Si compound periodic multilayer film, Si / Nb periodic multilayer film, Si / Mo / Ru periodic multilayer film, Si / Mo / Ru / Mo periodic multilayer film, Si / Ru / Mo / Ru periodic multilayer film and the like can be used. The material of the multilayer reflective film can be selected in consideration of the exposure wavelength.

The reflectance of such a multilayer reflective film 14 alone is, for example, 65% or more. The upper limit of the reflectance of the multilayer reflective film 14 is, for example, 73%. The thickness and period of the layers contained in the multilayer reflective film 14 can be selected so as to satisfy Bragg's law.

The multilayer reflective film 14 can be formed by a known method. The multilayer reflective film 14 can be formed by, for example, an ion beam sputtering method.

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

<Protective film>
The substrate 10 with a multilayer reflective film of the present embodiment may include a protective film 18 formed on the multilayer reflective film 14. The protective film 18 has a function of protecting the multilayer reflective film 14 when patterning or modifying the pattern of the absorber film described later. The protective film 18 is provided, for example, between the multilayer reflective film 14 and the absorber film.

Examples of the material of the protective film 18 include 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, and B can be used. In addition, compounds to which nitrogen, oxygen or carbon are added can be used. Of these, when a material containing ruthenium (Ru) is applied, the reflectance characteristics of the multilayer reflective film become better. Specifically, the material of the protective film 18 is preferably Ru or a Ru- (Nb, Zr, Y, B, Ti, La, Mo, Co or Re) compound. The thickness of the protective film 18 is, for example, 1 nm to 5 nm. The protective film 18 can be formed by a known method. The protective film 18 can be formed by, for example, a magnetron sputtering method or an ion beam sputtering method.

The substrate 10 with a multilayer reflective film may further have a back surface conductive film on the main surface of the substrate 12 opposite to the side on which the multilayer reflective film 14 is formed. The back surface conductive film is used when the substrate 10 with the multilayer reflective film or the reflective mask blank is adsorbed by the electrostatic chuck.

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

<Standard mark>
FIG. 2 is a plan view of the substrate 10 with a multilayer reflective film of the present embodiment.
As shown in FIG. 2, reference marks 20 are formed in the vicinity of the four corners of the 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 reference marks 20 are formed, the number of reference marks 20 may be four or more. Further, the four or more reference marks 20 may be arranged on at least two axes.

In the substrate 10 with the multilayer reflective film shown in FIG. 2, an absorber film pattern is formed in the region inside the broken line A (region of 132 mm × 132 mm) when the reflective mask is manufactured. In the region outside the broken line A, no absorber film pattern is formed when the reflective mask is manufactured. The reference mark 20 is preferably formed in a region where the absorber membrane pattern is not formed, that is, above the broken line A or outside the broken line A.

As shown in FIG. 2, the reference mark 20 has a substantially cross-shaped shape. The widths W1 and W2 of the reference mark 20 having a substantially cross 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. FIG. 2 shows an example of the reference mark 20 having a substantially cross-shaped shape, but the shape of the reference mark 20 is not limited to this. The shape of the reference mark 20 may be, for example, substantially L-shaped, circular, triangular, quadrangular, or the like in a plan view.

The cross-sectional shape of the reference mark 20 is, for example, concave. The term "concave" as used herein means that when the cross section of the substrate 10 with the multilayer reflective film (cross section perpendicular to the main surface of the substrate 10 with the multilayer reflective film) is viewed, the reference mark 20 is directed downward, for example, in a stepped shape. It means that it is formed so as to be recessed in a curved shape. The depth D of the concave reference mark 20 is preferably 30 nm or more. The depth D of the reference mark 20 may be the depth at which the substrate 12 is exposed, but is preferably 100 nm or less, and more preferably 50 nm or less. When the depth D is small, the effect of the present invention can be obtained more remarkably. The depth D means the vertical distance from the surface of the substrate 10 with the multilayer reflective film to the deepest position of the bottom of the reference mark 20.

The method of forming the reference mark 20 is not particularly limited. The reference mark 20 can be formed, for example, by laser processing on the surface of the substrate 10 with the multilayer reflective film. At this time, the reference mark 20 may be formed after the multilayer reflection film 14 is formed, and then the protective film 18 may be formed, or the multilayer reflection film 14 and the protective film 18 may be formed, and then the reference mark 20 is formed. It may be formed. The laser processing conditions are as follows, for example.
Laser type (wavelength): Ultraviolet to visible light range. For example, a semiconductor laser having a wavelength of 405 nm.
Laser output: 1-120 mW
Scan speed: 0.1 to 20 mm / s
Pulse frequency: 1-100 MHz
Pulse width: 3ns to 1000s

The laser used for laser processing the reference mark 20 may be a continuous wave or a pulse wave. When a pulse wave is used, the width W of the reference mark 20 can be made smaller than that of a continuous wave even if the depth D of the reference mark 20 is about the same. Therefore, when a pulse wave is used, it is possible to form a reference mark 20 which has a higher contrast than a continuous wave and is easily detected by a defect inspection device or an electron beam drawing device.

The method of forming the reference mark 20 is not limited to the laser. The reference mark 20 can be formed by, for example, a photolithography method, a FIB (focused ion beam), a processing mark obtained by scanning a diamond needle, an indentation by a microindenter, an embossing by an imprint method, or the like.

The cross-sectional shape of the reference mark 20 is not limited to the 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 by FIB, sputtering method, or the like. The height H of the convexly formed reference mark 20 is preferably 30 nm or more. 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 small, the effect of the present invention can be obtained more remarkably. The height H means the vertical distance from the surface of the substrate 10 with the multilayer reflective film to the highest position of the reference mark 20.

When the reference mark 20 is formed on the substrate 10 with the multilayer reflective film, the coordinates of the reference mark 20 and the defect are acquired with high accuracy by the defect inspection device. Next, an absorber film is formed on the protective film 18 of the substrate 10 with the multilayer reflective film. 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 is transferred to the absorber film and the resist film. When a hard mask film is formed between the absorber film and the resist film, the concave reference mark 20 formed on the substrate 10 with the multilayer reflective film is transferred to the absorber film, the hard mask film and the resist film. ..

Therefore, the reference mark 20 formed on the substrate 10 with the multilayer reflective film needs to have a high contrast that can be detected by the defect inspection device. Examples of the defect inspection device include a mask / substrate / blank defect inspection device “MAGICSM7360” manufactured by Lasertec Co., Ltd. for EUV exposure having an inspection light source wavelength of 266 nm, and an EUV manufactured by KLA-Tencor Co., Ltd. having an inspection light source wavelength of 193 nm. -A mask / blank defect inspection device "Teron 600 series, for example, Teron 610" or an ABI (Actinic Blank Inspection) device whose inspection light source wavelength is the same as the exposure light source wavelength of 13.5 nm can be used.

Further, the reference mark 20 transferred to the absorber film and / or the resist film on the absorber film needs to have a high contrast that can be detected by a coordinate measuring instrument and / or an electron beam drawing apparatus. Examples of the coordinate measuring instrument include "LMS-IPRO4" manufactured by KLA-Tencor, which measures coordinates with a laser having a wavelength of 365 nm, "PROVE" manufactured by Carl Zeiss, which measures coordinates with a laser having a wavelength of 193 nm, and / or. A coordinate measuring instrument mounted on an electron beam drawing apparatus can be used. The effect of the present invention can be obtained more remarkably when the wavelength of the coordinate measuring instrument is different from that of the above-mentioned defect inspection device.

The reference mark 20 can be used as, for example, an FM (fiducial mark). FM is a mark used as a reference of defect coordinates when drawing a pattern by an electron beam drawing apparatus. The FM usually has a cross shape as shown in FIG.

By using the reference mark 20 as FM, the defect coordinates can be managed with high accuracy. When drawing a pattern on the resist film by an electron beam drawing apparatus, the reference mark 20 transferred to the resist film is used as FM which is a reference of the defect position. For example, by detecting FM by an electron beam drawing apparatus, the defect coordinates acquired by the defect inspection apparatus can be converted into the coordinate system of the electron beam drawing apparatus. Thereby, for example, the drawing data of the pattern drawn by the electron beam drawing apparatus can be corrected so that the defect is arranged under the absorber film pattern. By correcting the drawing data, it is possible to reduce the influence of defects on the finally manufactured reflective mask.

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 a defect inspection device inspects a defect on the substrate 10 with a multilayer reflective film. However, AM is not used directly when drawing a pattern by an electron beam lithography system. The shape of the AM in a plan view is, for example, a circle, a quadrangle, or a cross.

When AM is formed on the substrate 10 with a multilayer reflective film, FM is formed on the laminated film described later on the substrate 10 with a multilayer reflective film. AM is transferred to the laminated film, but the detection accuracy of AM can be improved by partially removing the laminated film on AM. AM can be detected by a defect inspection device and a coordinate measuring instrument. FM can be detected by a coordinate measuring instrument and an electron beam drawing device. Since both AM and FM can be detected by a coordinate measuring instrument, their relative positional relationships can be managed with high accuracy. Therefore, the defect coordinates based on AM acquired by the defect inspection apparatus can be converted into the defect coordinates based on FM used in the electron beam drawing apparatus with high accuracy. The number of AMs is larger than the number of FMs.

The substrate 10 with a multilayer reflective film of the present embodiment has four or more (for example, N) reference marks 20 (four reference marks in FIG. 2) that serve as a reference for the position of defects in the substrate 10 with a multilayer reflective film. The value of 3σ obtained by the following procedures (1) to (5) is less than 50 nm.
(1) The defect inspection apparatus having the first coordinate system acquires the first defect coordinates of the defects in the substrate 10 with the multilayer reflective film and the first reference mark coordinates of the reference mark 20.
(2) The coordinate measuring instrument having the second coordinate system acquires the second defect coordinates of the defect in the substrate 10 with the multilayer reflective film and the second reference mark coordinates of the reference mark 20.
(3) To convert the coordinates from the first coordinate system of the defect inspection device to the second coordinate system of the coordinate measuring instrument based on the first reference mark coordinates and the second reference mark coordinates. Calculate the conversion factor.
(4) Using the conversion coefficient calculated in (3) above, the first defect coordinates acquired by the defect inspection device in (1) above are used with reference to the second coordinate system of the coordinate measuring instrument. Convert to the defect coordinates of 3.
(5) The value of 3σ is obtained for the difference between the second defect coordinates acquired by the coordinate measuring instrument in (2) above and the third defect coordinates converted in (4) above.

In the above procedure (1), the defect inspection device acquires the first defect coordinates of the defects in the substrate 10 with the multilayer reflective film and the first reference mark coordinates (x, y) of the N reference marks 20. .. As the defect inspection device, for example, the above-mentioned defect inspection device can be used. Further, the number of defects for obtaining the value of 3σ is preferably 3 or more, more preferably 9 or more, and further preferably 15 or more. Further, it is preferable that the variation in the size of the N reference marks is small. For example, the size of the N reference marks is preferably within ± 5%, more preferably within ± 3% of their average value. The "size" here means, for example, the area of the reference mark in a plan view.

In the above procedure (2), the second defect coordinates of the defects in the substrate 10 with the multilayer reflective film and the second reference mark coordinates (u, v) of the N reference marks 20 are acquired by the coordinate measuring instrument. .. As the coordinate measuring instrument, for example, the coordinate measuring instrument described above can be used.

When detecting the coordinates in the above procedures (1) and (2), for example, the origin can be set at the center of the substrate. Alternatively, the origin may be set at an arbitrary corner of the substrate after acquiring the edge coordinates of eight locations (two locations per side) of the four sides of the substrate and performing appropriate tilt correction.

As shown in FIG. 2, when the shape of the reference mark 20 is a cross shape, the coordinates of the reference mark 20 are the center line of the width W1 between the edges and the width W2 by detecting the edge of the reference mark 20. It can be set at the intersection with the center line of.

In the above procedure (3), the first reference mark coordinates (x, y) of the N reference marks 20 acquired in the procedure (1) and the Nth reference mark 20 acquired in the procedure (2). Based on the reference mark coordinates (u, v) of 2, 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 instrument is calculated. For the calculation of the conversion coefficient, for example, a linear transformation (affine transformation) can be used. Hereinafter, an example of a method for calculating the conversion coefficient using the affine transformation will be described.

_{N coordinate data (x 1} , y ₁ ), (x ₂ , y ₂ ), ・ ・ ・, (x _n , y _n ) acquired by the defect inspection device and n acquired by the corresponding coordinate measuring instrument. pieces of the coordinate data _{(u 1, v 1),} (u 2, v 2), · · ·, when there is (u _n, v _n), first from the first coordinate system of the defect inspection apparatus of the coordinate measuring instrument An affine transformation can be used for the transformation to the coordinate system of 2.

In the affine transformation, the transformation coefficients for x and y are independent, so x and y can be solved separately. Taking the formula for x as an example, when the i-th coordinate data is substituted into the formula for affine transformation, x _i = au _i + bv _i + c, but there is an error in the derived transformation formula, so This formula does not hold. The error amount [delta] _i is simply become minus the left from the right _{side, δ i = au i + bv} i + c - a x _i.

Here, if there are n coordinate data, it is possible to formulate an equation for n error quantities. Use the least squares method to find a, b, and c that minimize their error. Here, the error function φ of the sum of squares can be expressed by the following equation.

Since this function φ is a quadratic function, this equation is partially differentiated by a, b, c in order to find a, b, c that minimizes this function. Partial differentiation results in a function that represents the gradient of the error function, so the minimum value is where the partially differentiated function is 0, which is also the minimum value. This can be expressed by an equation as follows.

Since these equations are simultaneous linear equations, the following determinants can be obtained by arranging them using a matrix. By solving this system of equations, it is possible to find a, b, c, that is, the conversion coefficient, which minimizes the error. We have described x, but y can be solved in the same way.

In the above procedure (4), the conversion coefficient calculated in the above (3) is used to transfer the first defect coordinates acquired by the defect inspection device in the above (1) to the second coordinate system of the coordinate measuring instrument. Convert. For the coordinate transformation, for example, the affine transformation formula x _i = au _i + bv _i + c can be used.

In the above procedure (5), the value of 3σ is set for the difference between the second defect coordinate acquired by the coordinate measuring instrument in the above (2) and the third defect coordinate converted in the above (4). Ask. That is, the difference between the second defect coordinates "actually" obtained by the coordinate measuring instrument and the third defect coordinates converted to the second coordinate system of the coordinate measuring instrument using the conversion coefficient is 3σ. Find the value. 3σ is three times the standard deviation σ. A small 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 instrument is high.

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

As will be described later, the present inventors have found that 3σ tends to be inversely proportional to ^{N 1/2 when the number of reference marks 20 is N.} That is, it was found that the following equation holds when the proportionality constant is α.

3σ = α / N ^1/2 ... (1)

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

According to this, as the number of reference marks 20 increases, the conversion accuracy of the defect coordinates can be improved, and the number of reference marks 20 can be determined based on a desired 3σ. The number of reference marks 20 is preferably 4 or more, and 3σ can be less than 50 nm. Further, the number of reference marks 20 is more preferably 8 or more, and 3σ can be set to less than 25 nm. Further, the number of reference marks 20 is more preferably 16 or more, and 3σ can be set to less than 20 nm. Further, from the viewpoint of increasing the man-hours for forming the reference mark 20 and increasing the number of defects if the reference mark 20 is too large, the number of the reference marks 20 is preferably 100 or less. Further, when the number of the reference marks 20 exceeds 60, the decrease width of 3σ tends to be small, so that the number of the reference marks 20 is more preferably 60 or less.

In the substrate 10 with a multilayer reflective film of the present embodiment, the value of 3σ obtained by the above procedures (1) to (5) is less than 50 nm. Preferably, the value of 3σ is less than 50 nm for both the x-coordinate and y-coordinate data. When the value of 3σ is 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 instrument can be improved.

As a result, the user who is provided with the substrate 10 with the multilayer reflective film can collate the defect position specified by the defect inspection device with the drawing data with high accuracy, and in the finally manufactured reflective mask. Defects can be reliably reduced.

(Second Embodiment)
In the second embodiment, another substrate with a multilayer reflective film is used to acquire the correspondence between the number of reference marks and 3σ, and the multilayer reflection having the number of reference marks determined based on the correspondence. It differs from the first embodiment in that it is a substrate with a film. Other than that, it is the same as that of the first embodiment.
That is, the substrate 10 with a multilayer reflective film of the present embodiment includes a reference mark 20 that serves as a reference for the position of a defect in the substrate 10 with a multilayer reflective film, and the number of the reference marks 20 is the following procedure (1). ) To (7), which is the number obtained in advance.
(1) The defect inspection device having the first coordinate system acquires the first defect coordinates of the defect in another substrate with a multilayer reflective film having a plurality of reference marks and the first reference mark coordinates of the reference mark. do.
(2) The coordinate measuring instrument having the second coordinate system acquires the second defect coordinates of the defect and the second reference mark coordinates of the reference mark in the substrate with the other multilayer reflective film.
(3) Based on the first reference mark coordinates and the second reference mark coordinates, a conversion coefficient for converting the coordinates from the first coordinate system to the second coordinate system is calculated.
(4) Using the conversion coefficient calculated in (3) above, the first defect coordinates acquired by the defect inspection apparatus in (1) above are used as a third reference to the second coordinate system. Convert to defect coordinates of.
(5) The value of 3σ is obtained for the difference between the second defect coordinate acquired by the coordinate measuring instrument in the above (2) and the third defect coordinate converted in the above (4).
(6) Acquire the correspondence between the number of reference marks and 3σ.
(7) The number of reference marks having a desired value of 3σ (for example, less than 50 nm) is determined.

The above procedures (1) to (5) are the same as the procedures (1) to (5) of the first embodiment except that another substrate with a multilayer reflective film is used.

The defect in another substrate with a multilayer reflective film may be an actual defect or a program defect.
Further, another substrate with a multilayer reflective film may be a substrate with a single multilayer reflective film on which N reference marks are formed. In this case, for one substrate with a multilayer reflective film, the above steps (1) to (6) are performed to obtain the correspondence between the number of reference marks and 3σ, and the above correspondence is performed in the procedure (7). Determine the number of reference marks based on the relationship.

Another substrate with a multilayer reflective film may be a substrate with a plurality of multilayer reflective films on which 4 to N reference marks different from each other are formed. In this case, the above procedures (1) to (5) are performed for each substrate with a multilayer reflective film, and the correspondence between the number of reference marks and 3σ is obtained in the procedure (6), and the procedure (7) Determines the number of reference marks based on the correspondence.
In the present embodiment, since the number of reference marks is determined by using another substrate with a multilayer reflective film, the optimum number of reference marks 20 is provided according to the shape of the reference marks, the defect inspection device, and / or the coordinate measuring instrument. A substrate 10 with a multilayer reflective film can be obtained.

(Third Embodiment)
[Reflective mask blank]
FIG. 3 is a schematic view showing a cross section of the reflective mask blank 30 of the present embodiment. The reflective mask blank 30 of the present embodiment can be manufactured by forming the laminated film 28 on the protective film 18 of the substrate 10 with the multilayer reflective film described above. 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 has a function of absorbing EUV light, which is exposure light. That is, the difference between the reflectance of the multilayer reflective film 14 (including the protective film 18 if there is a protective film 18) to EUV light and the reflectance of the absorber film to EUV light is a predetermined value or more. .. For example, the reflectance of the absorber membrane 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 this case, the absorber film in the reflective mask blank 30 may be called a phase shift film.

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

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

As the material of the absorber membrane, for example, tantalum (Ta) alone or a material containing Ta is preferable. The materials containing Ta include, for example, a material containing Ta and B, a material containing Ta and N, a material containing Ta and B, and at least one of O and N, a material containing Ta and Si, and Ta and Si. A material containing N, a material containing Ta and Ge, a material containing Ta, Ge and N, a material containing Ta and Pd, a material containing Ta and Ru, a material containing Ta and Ti, and the like.

The absorber membrane is composed of, for example, a simple substance of Ni, a material containing Ni, a simple substance of Cr, a material containing Cr, a simple substance of Ru, a material containing Ru, a simple substance of Pd, a material containing Pd, a simple substance of Mo, and a material containing Mo. It may contain at least one selected from the group.

The thickness of the absorber membrane is preferably 30 nm to 100 nm.
The absorber membrane can be formed by a known method, for example, a magnetron sputtering method, an ion beam sputtering method, or the like.

In the reflective mask blank 30 of the present embodiment, the resist film 32 may be formed on the absorber film (laminated film 28). This aspect is shown in FIG. A resist pattern can be formed by drawing and exposing a pattern on the resist film 32 with an electron beam drawing apparatus and then undergoing a developing step. By performing dry etching on the absorber film using this resist pattern as a mask, a pattern can be formed on the absorber film.

In the reflective mask blank 30 of the present embodiment, the laminated film 28 may include an absorber film and a hard mask film formed on the absorber film. The hard mask membrane is used as a mask when patterning the absorber membrane. The hard mask film and the absorber film are formed of materials having different etching selectivity. When the material of the absorber membrane contains tantalum or a tantalum compound, the material of the hard mask membrane preferably contains chromium or a chromium compound. The chromium compound preferably comprises Cr and at least one selected from the group consisting of N, O, C, and H.

The reflective mask blank 30 of the present embodiment includes four or more (for example, N) reference marks 20 that serve as a reference for the position of defects on the substrate 10 with a multilayer reflective film. The absorber film (laminated film 28) formed on the substrate 10 with the multilayer reflective film may include a transfer reference mark to which the shape of the reference mark 20 is transferred. For example, when the reference mark 20 is concave, the concave transfer reference mark is formed on the absorber film (laminated film 28) formed on the reference mark 20. When the reference mark 20 is convex, the convex transfer reference mark is formed on the absorber film (laminated film 28) formed on the reference mark 20.

The reference mark 20 of the present embodiment is the same as the reference 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 shape are, for example, 200 nm or more and 10 μm or less. The deviation ΔW (= (| W1-W1'| / W1) × 100) of the width W1'(W2') of the transfer reference mark from the width W1 (W2) of the reference mark 20 may be 10% or less. preferable. Further, when the deviation ΔW is 1% or more, and further, when ΔW is 3% or more, the effect of the present invention can be obtained more remarkably. The length L'of the transfer reference mark is, for example, 100 μm or more and 1500 μm or less. The deviation ΔL (= (| L−L ′ | / L) × 100) of the transfer reference mark length L ′ from the length L of the reference mark 20 is preferably 1% or less. Further, when the deviation ΔL is 0.05% or more, the effect of the present invention can be obtained more remarkably.

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

When the reference mark 20 is concave (convex), the transfer reference mark is also concave (convex). The depth D'(height H') of the transfer 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) of the transfer reference mark depth D ′ (height H ′) from the reference mark 20 depth D (height H) is preferably 10% or less. Further, when the deviation ΔD (ΔH) is 0.05% or more, and further, when ΔD (ΔH) is 1% or more, the effect of the present invention can be obtained more remarkably.

When the absorber film (laminated film 28) has a transfer reference mark, the value of 3σ obtained by the following steps (1) to (5) may be less than 50 nm.
(1) The defect inspection apparatus having the first coordinate system acquires the first defect coordinates of the defects in the substrate 10 with the multilayer reflective film and the first reference mark coordinates of the reference mark 20.
(2) The second defect coordinate of the defect in the reflective mask blank 30 and the second reference mark coordinate of the transfer reference mark are acquired by the coordinate measuring instrument having the second coordinate system.
(3) To convert the coordinates from the first coordinate system of the defect inspection device to the second coordinate system of the coordinate measuring instrument based on the first reference mark coordinates and the second reference mark coordinates. Calculate the conversion factor.
(4) Using the conversion coefficient calculated in (3) above, the first defect coordinates acquired by the defect inspection device in (1) above are used with reference to the second coordinate system of the coordinate measuring instrument. Convert to the defect coordinates of 3.
(5) The value of 3σ is obtained for the difference between the second defect coordinates acquired by the coordinate measuring instrument in (2) above and the third defect coordinates converted in (4) above.

The above procedures (1) to (5) are the same as the procedures (1) to (5) in the substrate 10 with the multilayer reflective film of the first embodiment described above, but in the procedure (2), the coordinate measuring instrument is used. The difference is that the second defect coordinates of the defect in the reflective mask blank 30 and the second reference mark coordinates of the transfer reference mark are acquired.

The present inventors have found that 3σ tends to be inversely proportional to ^{N 1/2} when the number of reference marks 20 is N, as shown in Table 1 and FIG. 7 of Example 1 described later. rice field. That is, it was found that the following equation holds when the proportionality constant is α.

3σ = α / N ^1/2 ... (1)

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

FIG. 8 shows a graph of the above equation (1) in which α = 70 is substituted.
From this graph, it can be seen that as the number of reference marks 20 increases, the conversion accuracy of the defect coordinates improves. The number of reference marks 20 can be determined based on the desired 3σ. The number of reference marks 20 is preferably 4 or more, and 3σ can be less than 50 nm. Further, the number of reference marks 20 is more preferably 8 or more, and 3σ can be set to less than 25 nm. Further, the number of reference marks 20 is more preferably 16 or more, and 3σ can be set to less than 20 nm. Further, from the viewpoint of increasing the man-hours for forming the reference mark 20 and increasing the number of defects if the reference mark 20 is too large, the number of the reference marks 20 is preferably 100 or less. Further, when the number of the reference marks 20 exceeds 60, the decrease width of 3σ tends to be small, so that the number of the reference marks 20 is more preferably 60 or less.

In the reflective mask blank 30 of the present embodiment, the value of 3σ obtained by the above procedures (1) to (5) is less than 50 nm. Preferably, the value of 3σ is less than 50 nm for both the x-coordinate and y-coordinate data. When the value of 3σ is 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 instrument can be improved.

As a result, the user who is provided with the reflective mask blank 30 can collate the defect position identified by the defect inspection device with the drawing data with high accuracy, and the defect in the finally manufactured reflective mask can be collated. Can be reliably reduced.

In the reflective mask blank 30 of the present embodiment, the second reference mark coordinates of the transfer reference mark transferred to the absorber film (laminated film 28) are acquired in the above procedure (2). When drawing a pattern on the resist film with an electron beam drawing device, the FM on the absorber film is used as a reference, so by using the second reference mark coordinates of the transfer reference mark transferred to the absorber film. , The conversion accuracy of coordinates can be further improved. That is, when the absorber film (laminated film 28) is formed on the reference mark, the position of the detected reference mark changes by changing the width and depth of the transfer reference mark transferred to the absorber film. In some cases. By acquiring the second reference mark coordinates of the transfer reference mark transferred to the absorber membrane and calculating the conversion coefficient based on the acquired second reference mark coordinates, the influence of the displacement of the reference mark is considered. It is possible to calculate the converted conversion coefficient. As a result, it becomes possible to further improve the conversion accuracy of the coordinates in the above procedure (4).

(Fourth Embodiment)
In the fourth embodiment, another substrate with a multilayer reflective film and another reflective mask blank having a laminated film on the substrate with the other multilayer reflective film are used to set the number of reference marks and 3σ. The third embodiment is different from the third embodiment in that the reflective mask blank 30 has a correspondence relationship and has a number of reference marks determined based on the correspondence relationship. Other than that, it is the same as that of the third embodiment.

That is, the reflective mask blank 30 of the present embodiment includes a reference mark 20 that serves as a reference for the position of defects on the substrate 10 with a multilayer reflective film. The absorber film (laminated film 28) formed on the substrate 10 with the multilayer reflective film includes a transfer reference mark to which the shape of the reference mark 20 is transferred. The number of the reference marks 20 is the number obtained in advance by the following procedures (1) to (7).
(1) The defect inspection device having the first coordinate system acquires the first defect coordinates of the defect in another substrate with a multilayer reflective film having a plurality of reference marks and the first reference mark coordinates of the reference mark. do.
(2) Second defect coordinates and transfer of defects in another reflective mask blank having a laminated film formed on the substrate with another multilayer reflective film by a coordinate measuring instrument having a second coordinate system. Acquire the second reference mark coordinates of the reference mark.
(3) Based on the first reference mark coordinates and the second reference mark coordinates, a conversion coefficient for converting the coordinates from the first coordinate system to the second coordinate system is calculated.
(4) Using the conversion coefficient calculated in (3) above, the first defect coordinates acquired by the defect inspection apparatus in (1) above are used as a third reference to the second coordinate system. Convert to defect coordinates of.
(5) The value of 3σ is obtained for the difference between the second defect coordinate acquired by the coordinate measuring instrument in the above (2) and the third defect coordinate converted in the above (4).
(6) Acquire the correspondence between the number of reference marks and 3σ.
(7) The number of reference marks having a desired value of 3σ (for example, less than 50 nm) is determined.
The above steps (1) to (5) are the same as the steps (1) to (5) of the third embodiment except that another substrate with a multilayer reflective film and another reflective mask blank are used. be.
Another substrate with a multilayer reflective film is the same as in the third embodiment. Another reflective mask blank has a plurality of transfer reference marks to which the reference marks formed on another substrate with a multilayer reflective film are transferred.

In this embodiment, since the number of reference marks is determined by using another substrate with a multilayer reflective film and another reflective mask blank, the shape of the reference mark, the shape of the transfer reference mark, the defect inspection device, and / or the coordinate measuring instrument. Therefore, it is possible to obtain a substrate 10 with a multilayer reflective film having an optimum number of reference marks 20.

[Manufacturing method of reflective mask]
The reflective mask 40 of the present embodiment can be manufactured by using the reflective mask blank 30 of the present embodiment. Hereinafter, a method for manufacturing the reflective mask 40 will be described.

FIG. 4 is a schematic view showing a method of manufacturing the reflective mask 40.
As shown in FIG. 4, first, the substrate 12, the multilayer reflective film 14 formed on the substrate 12, the protective film 18 formed on the multilayer reflective film 14, and the protective film 18 are formed. A reflective mask blank 30 having an absorber film (laminated film 28) is prepared (FIG. 4 (a)). Next, a resist film 32 is formed on the absorber film (FIG. 4 (b)). A pattern is drawn on the resist film 32 by an electron beam drawing apparatus, and a resist pattern 32a is formed by further undergoing a developing and rinsing process (FIG. 4C).

The absorber film (laminated film 28) is dry-etched using the resist pattern 32a as a mask. As a result, 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)).

As the etching gas, for example, _{chlorine-based gas such as Cl 2} , SiCl ₄ , CHCl ₃ , and CCl ₄ , mixed gas containing these chlorine-based gas and O ₂ in a predetermined ratio, chlorine-based gas and He are specified. Mixed gas containing in proportion, mixed gas containing chlorine-based gas and Ar in a predetermined proportion, CF ₄ , CHF ₃ , C ₂ F ₆ , C ₃ F ₆ , C ₄ F ₆ , C ₄ F ₈ , CH ₂ F ₂ , CH ₃ F, C ₃ F ₈ , SF ₆ , F, etc., Fluorine-based gas, _{mixed gas containing these fluorine-based gas and O 2} in a predetermined ratio, mixed gas containing fluorine-based gas and He in a predetermined ratio, A mixed gas or the like containing a fluorine-based gas and Ar in a predetermined ratio can be used.

After the absorber membrane pattern 28a is formed, the resist pattern 32a is removed, for example, with a resist stripping solution. After removing the resist pattern 32a, the reflective mask 40 of the present embodiment is obtained by undergoing a wet cleaning step using an acidic or alkaline aqueous solution (FIG. 4 (e)).

[Manufacturing method of semiconductor devices]
A transfer pattern can be formed on the semiconductor substrate by lithography using the reflective mask 40 of the present embodiment. This transfer pattern has a shape in which the absorber film pattern 28a of the reflective mask 40 is transferred. A semiconductor device can be manufactured by forming a transfer pattern on a semiconductor substrate with a reflective mask 40.

A method of transferring a pattern to the resisted semiconductor substrate 56 by EUV light will be described with reference to FIG.

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 reflection mirror is used as the reduction optical system 54.

The pattern reflected by the reflective mask 40 is usually reduced to about 1/4 by the reduction optical system 54. For example, a wavelength band of 13 to 14 nm is used as the exposure wavelength, and the optical path is set in advance so as to be in a vacuum. Under such conditions, the EUV light generated by the laser plasma X-ray source 52 is incident on the reflective mask 40. The light reflected by the reflective mask 40 is transferred onto the resisted semiconductor substrate 56 via the reduction optical system 54.

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

The light reflected by the reflective mask 40 is incident on the reduction optical system 54. The light incident on the reduction optical system 54 forms a transfer pattern on the resist layer on the resisted semiconductor substrate 56. By developing the exposed resist layer, a resist pattern can be formed on the resisted 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 through such a process and other necessary steps.

When the reference mark formed on the substrate with the multilayer reflective film is FM, the reflective mask blank of the present embodiment determines the number of FMs by, for example, the second embodiment or the fourth embodiment described above. However, it can be produced by the following method.
A method for manufacturing reflective mask blanks.
A process of forming a multi-layer reflective film on a substrate to form a substrate with a multi-layer reflective film,
A step of forming a determined number of FMs based on a desired 3σ on the surface of the substrate with a multilayer reflective film, and
By using the defect inspection device to acquire the first defect coordinates of the defects on the surface of the substrate with the multilayer reflective film and the first FM coordinates of the FM, the first FM coordinates are used as a reference. The process of acquiring a defect map showing the first defect coordinates, and
A method for producing a reflective mask blank, comprising a step of forming a laminated film having a transferred FM to which the FM is transferred on a substrate with a multilayer reflective film.

The user who is provided with the reflective mask blank and the defect map can collate the defect position specified by the defect inspection device with the drawing data with high accuracy based on the transfer FM, and finally manufacture the product. Defects can be reliably reduced in the reflective mask.

When the reference mark formed on the substrate with the multilayer reflective film is AM, the reflective mask blank of the present embodiment determines the number of AMs by, for example, the second embodiment or the fourth embodiment described above. However, it can be produced by the following method.
A method for manufacturing reflective mask blanks.
A process of forming a multi-layer reflective film on a substrate to form a substrate with a multi-layer reflective film,
A step of forming a determined number of AMs based on a desired 3σ on the surface of the substrate with a multilayer reflective film, and
By acquiring the first defect coordinates of the defects on the surface of the substrate with the multilayer reflective film and the first AM coordinates of the AM using the defect inspection device, the first AM coordinates are used as a reference. The process of acquiring the first defect map showing the defect coordinates of 1 and
A step of forming a laminated film having a transfer AM to which the AM is transferred on the substrate with a multilayer reflective film, and a step of forming a film.
The step of forming FM on the surface of the laminated film and
By acquiring the second AM coordinate of the transfer AM and the FM coordinate of the FM using the coordinate measuring instrument, the first defect map shows the first defect coordinate based on the FM coordinate. A method of manufacturing a reflective mask blank comprising a step of converting to a second defect map.

The user who is provided with the reflective mask blank and the second defect map can collate the defect position identified by the defect inspection device with the drawing data with high accuracy based on FM, and finally. Defects can be reliably reduced in the manufactured reflective mask.

Hereinafter, more specific examples of the present invention will be described.
<Example 1>
A SiO _2- TiO ₂ system glass substrate (6 inch square, thickness 6.35 mm) was prepared. The end face of this glass substrate was chamfered and ground, and further rough-polished with a polishing liquid containing cerium oxide abrasive grains. The glass substrate after these treatments was set in the carrier of the double-sided polishing apparatus, and precision polishing was performed under predetermined polishing conditions using an alkaline aqueous solution containing colloidal silica abrasive grains as the polishing liquid. After the precision polishing was completed, the glass substrate was cleaned. The surface roughness of the main surface of the obtained glass substrate was 0.10 nm or less in terms of root mean square roughness (RMS). The flatness of the main surface of the obtained glass substrate was 30 nm or less in the measurement region 132 mm × 132 mm.

A back surface conductive film made of CrN was formed on the back surface of the above glass substrate by a magnetron sputtering method 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 was formed by periodically laminating a Mo film / Si film on the main surface opposite to the side on which the back surface conductive film of the glass substrate was formed.

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

A protective film containing a Ru compound was formed on the multilayer reflective film. Specifically, a protective film made of a RuNb film is formed on a multilayer reflective film by DC magnetron sputtering in an Ar gas atmosphere using a RuNb target (Ru: 80 atomic%, Nb: 20 atomic%). bottom. The thickness of the protective film was 2.5 nm.

FM was formed on the protective film by laser processing.
The conditions for laser machining were as follows.
Laser type: Semiconductor laser with a wavelength of 405 nm Laser output: 20 mW (continuous wave)
Spot size: 430 nmφ

The shape and dimensions of the FM were as follows.
Shape: Approximately cross-shaped Depth D: 40 nm
Width W1, W2: 1 μm
Length L: 1mm

Eight FMs were formed.
The location where the FM was formed was as shown in FIG. 6, and was outside the effective region (region shown by the broken line) of 132 mm × 132 mm.

Using a defect inspection device (ABI, manufactured by Lasertec Co., Ltd.), the first defect coordinates of defects in the substrate with a multilayer reflective film and the first FM coordinates of FM were acquired. The number of defects was four.

An absorber film was formed on the protective film of the substrate with a multilayer reflective film to manufacture a reflective mask blank. Specifically, an absorber film composed of a laminated film of TaBN (thickness 56 nm) and TaBO (thickness 14 nm) was formed by DC magnetron sputtering. The TaBN film was formed by reactive sputtering in a mixed gas atmosphere of _{Ar gas and N 2 gas using a TaB target.} The TaBO membrane was formed by reactive sputtering in a mixed gas atmosphere of _{Ar gas and O 2 gas using a TaB target.} A transferred FM to which FM was transferred was formed on the laminated film.

Using a coordinate measuring instrument (LMS-IPRO4 manufactured by KLA-Tencor), the second defect coordinates of the defect in the reflective mask blank and the second FM coordinates of the transferred FM were acquired.

Using the acquired first FM coordinates and the second FM coordinates, 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 instrument was calculated. .. The above-mentioned affine transformation formula was used to calculate the transformation coefficient.

Using the calculated conversion coefficient, the first defect coordinates acquired by the defect inspection apparatus were converted into the second coordinate system of the coordinate measuring instrument to acquire the third defect coordinates.

The difference between the third defect coordinate obtained by the conversion and the second defect coordinate acquired by the coordinate measuring instrument was obtained for each of the X coordinate and the Y coordinate. Such "differences" (absolute values) were calculated for all defect data, and the standard deviation σ and 3σ for this "difference" were calculated. As a result, in the case of 8 FMs, 3σ had an X coordinate of 24.2 nm and a Y coordinate of 23.3 nm, both of which were less than 50 nm.

Further, the number of FMs was changed between 3 and 7, and the value of 3σ was calculated in the same manner as in the case where the number of FMs was 8 described above. The calculation results of 3σ when the number of FMs is 3 to 8 are shown in Table 1 below and the graph of FIG.

As shown in Table 1 and FIG. 7, when the number of FMs is 4 or more, 3σ is less than 50 nm in both the X coordinate and the Y coordinate, and the first coordinate system of the defect inspection device to the second coordinate of the coordinate measuring instrument. The conversion accuracy to the system was high.

A resist film was formed on the absorber film of the reflective mask blank produced above. A pattern was drawn on the resist film using an electron beam drawing apparatus. When drawing the pattern, four transfer FMs were used as the reference for the defect coordinates. After drawing the pattern, a predetermined development process was performed to form a resist pattern on the absorber film.

A pattern was formed on the absorber membrane using the resist pattern as a mask. Specifically, the upper TaBO film was dry-etched with a fluorine-based gas (CF ₄ gas), and then the lower TaBN film was dry-etched with a _{chlorine-based gas (Cl 2 gas).}

By removing the resist pattern remaining on the absorber film pattern with hot sulfuric acid, the reflective mask according to Example 1 was obtained. When the obtained EUV reflective mask was inspected with a mask defect inspection device (Teron 600 series manufactured by KLA-Tencor), no defect was confirmed in the exposed region of the multilayer reflective film of the absorber film pattern.

<Example 2>
A substrate with a multilayer reflective film and a reflective mask blank were manufactured in the same manner as in Example 1 above, except that the number of FMs was changed from 8 to 16.
The location where the FM was formed was as shown in FIG. 9, and was outside the effective region (region shown by the broken line) of 132 mm × 132 mm.

3σ was calculated in the same manner as in Example 1. As a result, in the case of 16 FMs, 3σ had an X coordinate of 18.2 nm and a Y coordinate of 18.0 nm, both of which were less than 50 nm.

Similar to Example 1, a reflective mask of Example 2 was obtained by drawing a pattern on the resist film with an electron beam drawing apparatus based on the position information of the defect based on the transfer FM. When the obtained EUV reflective mask was inspected with a mask defect inspection device (Teron 600 series manufactured by KLA-Tencor), no defect was confirmed in the exposed region of the multilayer reflective film of the absorber film pattern.

<Example 3>
The substrate with the multilayer reflective film and the reflective mask blank on which the eight FMs of Example 1 are formed are used as another substrate with the multilayer reflective film and another reflective mask blank, and the substrate with the multilayer reflective film of Example 3 is used. And a reflective mask blank was prepared.
From the correspondence between the number of FMs obtained in Example 1 and 3σ, the number of FMs having 3σ of less than 30 nm was calculated, and the number of FMs was set to 7.
In the same manner as in Example 1, a multilayer reflective film and a protective film were formed on the main surface of the glass substrate on the side opposite to the side on which the back surface conductive film was formed. FM was formed on the protective film by laser processing to prepare a substrate with a multilayer reflective film having 7 FMs.
The shape and dimensions of the FM were as follows.
Shape: Approximately cross-shaped Depth D: 40 nm
Width W1, W2: 1 μm
Length L: 1m

In the same manner as in the first embodiment, the defect inspection apparatus (ABI, manufactured by Lasertec Co., Ltd.) is used to acquire the first defect coordinates of the defects in the substrate with the multilayer reflective film and the first FM coordinates of the FM. A defect map showing the first defect coordinates with respect to the first FM coordinates was obtained. The number of defects was five.

In the same manner as in Example 1, a laminated film in which a transfer FM was formed was formed on the protective film to prepare a reflective mask blank. The deviation ΔD of the transfer FM depth D'from the FM depth D was almost 0. The deviations ΔW1 and ΔW2 of the FM widths W1 ′ and W2 ′ from the FM widths W1 and W2 were 7%, respectively. The deviation ΔL of the length L'of the transferred FM from the length L of the FM was 0.1%.

Using a coordinate measuring instrument (LMS-IPRO4 manufactured by KLA-Tencor), the second defect coordinates of the defect in the reflective mask blank and the second FM coordinates of the transferred FM were acquired. In the same manner as in the first embodiment, the first defect coordinates are converted into the second coordinate system of the coordinate measuring instrument, and the third defect coordinates obtained by the conversion and the second defect coordinates acquired by the coordinate measuring instrument are obtained. The difference from the defect coordinates was obtained for each of the X and Y coordinates. As a result, 3σ was less than 30 nm.

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

<Example 4>
Based on the result of FIG. 8 described above, 28 AMs having 3σ of less than 20 nm were calculated to prepare a substrate with a multilayer reflective film and a reflective mask blank of Example 4.
In the same manner as in Example 1, a multilayer reflective film and a protective film were formed on the main surface of the glass substrate on the side opposite to the side on which the back surface conductive film was formed.

AM was formed on the protective film by laser processing.
The conditions for laser machining were as follows.
Laser type: Semiconductor laser with a wavelength of 405 nm Laser output: 20 mW (continuous wave)
Spot size: 430 nmφ

The shape and dimensions of AM were as follows.
Shape: Approximately circular Depth: 40 nm
Diameter: 0.9 μm

28 AMs were formed.
The location of AM formation was as shown in FIG. 10, and was outside the effective region (region shown by the broken line) of 132 mm × 132 mm.

Using a defect inspection device (ABI, manufactured by Lasertec Co., Ltd.), the first defect coordinates of defects in the substrate with a multilayer reflective film and the first AM coordinates of 28 AMs were acquired.

An absorber film was formed on the protective film of the substrate with a multilayer reflective film to manufacture a reflective mask blank. Specifically, an absorber film composed of a laminated film of TaBN (thickness 56 nm) and TaBO (thickness 14 nm) was formed by DC magnetron sputtering. The TaBN film was formed by reactive sputtering in a mixed gas atmosphere of _{Ar gas and N 2 gas using a TaB target.} The TaBO membrane was formed by reactive sputtering in a mixed gas atmosphere of _{Ar gas and O 2 gas using a TaB target.} Twenty-eight transfer AMs to which AM was transferred were formed on the absorber film (laminated film). The deviation ΔD of the transfer AM depth D'from the AM depth D was almost 0. The deviation of the diameter of the transferred AM from the diameter of the AM was 6%.

FM was formed on the surface of the absorber membrane by FIB processing.
The conditions for FIB processing were as follows.
Acceleration voltage: 50kV
Beam current value: 20pA

The shape and dimensions of the FM were as follows.
Shape: Approximately cross-shaped Depth D: 70 nm
Width W1, W2: 5 μm
Length L: 1mm

Four FMs were formed.
The location where the FM was formed was as shown in FIG. 10, and was outside the effective region (region shown by the broken line) of 132 mm × 132 mm.

Using a coordinate measuring instrument (LMS-IPRO4 manufactured by KLA-Tencor), the second defect coordinates of the defects in the reflective mask blank and the second AM coordinates of the 28 transfer AMs were obtained.

To convert the coordinates from the first coordinate system of the defect inspection device to the second coordinate system of the coordinate measuring instrument by using the acquired first AM coordinate of AM and the second AM coordinate of the transfer AM. The conversion coefficient was calculated. The above-mentioned affine transformation formula was used to calculate the transformation coefficient.

Using the calculated conversion coefficient, the first defect coordinates acquired by the defect inspection apparatus were converted into the second coordinate system of the coordinate measuring instrument, and the third defect coordinates were acquired.

The difference between the third defect coordinate obtained by the conversion and the second defect coordinate acquired by the coordinate measuring instrument was obtained for each of the X coordinate and the Y coordinate. Such "differences" (absolute values) were calculated for all defect data, and the standard deviation σ and 3σ for this "difference" were calculated. As a result, when the number of AMs was 28, 3σ had an X coordinate of 14.9 nm and a Y coordinate of 14.1 nm, both of which were less than 50 nm.

A resist film was formed on the absorber film of the reflective mask blank produced above. A pattern was drawn on the resist film using an electron beam drawing apparatus. When drawing the pattern, FM was used as the reference for the defect coordinates. Specifically, the relative positional relationship between the transfer AM and FM was acquired by a coordinate measuring instrument. Using this positional relationship, the position information of the defect based on AM was converted into the position information of the defect based on FM. A pattern was drawn on the resist film by an electron beam drawing apparatus based on the position information of the defect based on FM.

A pattern was formed on the absorber membrane using the resist pattern as a mask. Specifically, the upper TaBO film was dry-etched with a fluorine-based gas (CF ₄ gas), and then the lower TaBN film was dry-etched with a _{chlorine-based gas (Cl 2 gas).}

By removing the resist pattern remaining on the absorber film pattern with hot sulfuric acid, the reflective mask according to Example 4 was obtained. When the obtained EUV reflective mask was inspected with a mask defect inspection device (Teron 600 series manufactured by KLA-Tencor), no defect was confirmed in the exposed region of the multilayer reflective film of the absorber film pattern.

<Comparative example 1>
A substrate with a multilayer reflective film and a reflective mask blank were manufactured in the same manner as in Example 1 above, except that the number of FMs was changed from 8 to 3.
The location where the FM was formed was as shown in FIG. 11, and was outside the effective region (region shown by the broken line) of 132 mm × 132 mm.

3σ was calculated in the same manner as in Example 1. As a result, when 3 FMs were used, 3σ had an X coordinate of 62.7 nm and a Y coordinate of 57.3 nm, both of which were 50 nm or more.

Similar to Example 1, a reflective mask of Comparative Example 1 was obtained by drawing a pattern on the resist film with an electron beam drawing apparatus based on the position information of the defect based on the transfer FM. When the obtained EUV reflective mask was inspected with a mask defect inspection device (Teron 600 series manufactured by KLA-Tencor), the defect could not be hidden under the absorber film pattern due to the poor coordinate conversion accuracy. Defects were found in the exposed area of the multilayer reflective film.

10 Substrate with multi-layer reflective film 12 Substrate 14 Multi-layer reflective film 18 Protective film 20 Reference mark 28 Laminated film 30 Reflective mask blank 40 Reflective mask 50 Pattern transfer device 56 Semiconductor substrate

Claims (10)

A substrate with a multilayer reflective film having a substrate and a multilayer reflective film formed on the substrate that reflects EUV light.
It is provided with a reference mark that serves as a reference for the position of defects in the substrate with a multilayer reflective film.
A substrate with a multilayer reflective film, wherein the number of reference marks is the number obtained in advance by the following procedures (1) to (7).
(1) The defect inspection device having the first coordinate system acquires the first defect coordinates of the defect in another substrate with a multilayer reflective film having a plurality of reference marks and the first reference mark coordinates of the reference mark. do.
(2) The coordinate measuring instrument having the second coordinate system acquires the second defect coordinates of the defect and the second reference mark coordinates of the reference mark in the substrate with the other multilayer reflective film.
(3) Based on the first reference mark coordinates and the second reference mark coordinates, a conversion coefficient for converting the coordinates from the first coordinate system to the second coordinate system is calculated.
(4) Using the conversion coefficient calculated in (3) above, the first defect coordinates acquired by the defect inspection apparatus in (1) above are used as a third reference to the second coordinate system. Convert to defect coordinates of.
(5) The value of 3σ is obtained for the difference between the second defect coordinate acquired by the coordinate measuring instrument in the above (2) and the third defect coordinate converted in the above (4).
(6) Acquire the correspondence between the number of reference marks and 3σ.
(7) Determine the number of reference marks whose value of 3σ is less than 50 nm. The substrate with a multilayer reflective film according to claim 1, wherein the number of the reference marks is 8 or more. The substrate with a multilayer reflective film according to claim 1 or 2, wherein the number of the reference marks is 16 or more. A reflective mask blank having a substrate with a multilayer reflective film according to any one of claims 1 to 3 and a laminated film formed on the substrate with a multilayer reflective film. A reflective mask blank having a substrate, a substrate with a multilayer reflective film having a multilayer reflective film for reflecting EUV light formed on the substrate, and a laminated film formed on the substrate with a multilayer reflective film.
The multi-layer reflective film-equipped substrate has a reference mark that serves as a reference for the position of defects in the multi-layer reflective film-equipped substrate.
The laminated film includes a transfer reference mark to which the reference mark is transferred.
A reflective mask blank, characterized in that the number of reference marks is the number obtained in advance by the following procedures (1) to (7).
(1) The defect inspection device having the first coordinate system acquires the first defect coordinates of the defect in another substrate with a multilayer reflective film having a plurality of reference marks and the first reference mark coordinates of the reference mark. do.
(2) The second defect coordinates of the defect in the reflective mask blank having the laminated film formed on the substrate with the other multilayer reflective film by the coordinate measuring instrument having the second coordinate system, and the transfer reference mark. Acquires the second reference mark coordinates of.
(3) Based on the first reference mark coordinates and the second reference mark coordinates, a conversion coefficient for converting the coordinates from the first coordinate system to the second coordinate system is calculated.
(4) Using the conversion coefficient calculated in (3) above, the first defect coordinates acquired by the defect inspection apparatus in (1) above are used as a third reference to the second coordinate system. Convert to defect coordinates of.
(5) The value of 3σ is obtained for the difference between the second defect coordinate acquired by the coordinate measuring instrument in the above (2) and the third defect coordinate converted in the above (4).
(6) Acquire the correspondence between the number of reference marks and 3σ.
(7) Determine the number of reference marks whose value of 3σ is less than 50 nm. The reflective mask blank according to claim 5, wherein the number of the reference marks is 8 or more. The reflective mask blank according to claim 5 or 6, wherein the number of the reference marks is 16 or more. The reflective mask blank according to any one of claims 4 to 7, wherein the laminated film includes an absorber film that absorbs EUV light. A method for producing a reflective mask, comprising a step of forming a laminated film pattern on the laminated film in the reflective mask blank according to claim 4 or 8. A method for manufacturing a semiconductor device, comprising a step of forming a transfer pattern on a semiconductor substrate using the reflective mask manufactured by the method for manufacturing a reflective mask according to claim 9.

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