Spatial resolution measurement sample, method for manufacturing spatial resolution measurement sample, and method for measuring spatial resolution

Abstract

To provide a sample for measuring spatial resolution that can measure resolution in the range of 0.5 nm to 5 nm.SOLUTION: A spatial resolution measurement sample 10 is a sample for measuring the spatial resolution of a transmission electron microscope, and includes a substrate 2 and a stack 4 formed on the substrate 2, the stack 4 includes a first layer 40, a second layer 42, and a third layer 44, the first layer 40 is located between the second layer 42 and the third layer 44, the density of the first layer 40 is greater than the density of the second layer 42 and the density of the third layer 44, and the film thickness of the first layer 40 is 0.5 nm or more and 5 nm or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a sample for spatial resolution measurement, a method for manufacturing a sample for spatial resolution measurement, and a method for measuring spatial resolution. [Background technology]

[0002] Transmission electron microscopes with high spatial resolution on the order of angstroms are known. Spatial resolution (hereinafter simply referred to as "resolution") is the minimum distance at which two spatially separated points can be distinguished. Transmission electron microscopes with angstrom-order resolution can measure resolution from the lattice spacing of single crystals or polycrystals. Furthermore, scanning electron microscopes with nanometer-order resolution can measure resolution by measuring the gap length between particles using a sample in which gold particles are vapor-deposited on carbon, as disclosed in Patent Document 1.

[0003] In recent years, time-resolved measurements have become possible using transmission electron microscopes equipped with a pulsed electron beam generation mechanism that utilizes the photoelectric effect caused by pulsed laser irradiation.Known transmission electron microscopes capable of time-resolved measurements include Dynamic TEM (DTEM), which acquires TEM images by single-shot photography, and Ultrafast TEM (UTEM), which achieves time-resolved TEM imaging by stroboscopic photography. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-109960 Summary of the Invention [Problem to be solved by the invention]

[0005] The resolution of UTEM and DTEM is on the order of a few nanometers. Transmission electron microscopes with a resolution of a few nanometers cannot measure the resolution from the lattice spacing of single crystals or polycrystals. Furthermore, there are no specimens in nature that can be measured with a resolution of a few nanometers. [Means for solving the problem]

[0006] One aspect of the spatial resolution measurement sample according to the present invention is A sample for measuring spatial resolution of a transmission electron microscope, A substrate; a laminate formed on the substrate; Including, the laminate includes a first layer, a second layer, and a third layer; the first layer is located between the second layer and the third layer; the density of the first layer is greater than the density of the second layer and the density of the third layer; The first layer has a thickness of 0.5 nm or more and 5 nm or less.

[0007] In such a sample for measuring spatial resolution, the spatial resolution can be measured in the range of 0.5 nm to 5 nm by measuring the film thickness of the first layer.

[0008] One aspect of the method for producing a spatial resolution measurement sample according to the present invention is to A method for producing a sample for measuring spatial resolution of a transmission electron microscope, comprising: forming a laminate including a first layer, a second layer, and a third layer on a substrate; Slicing the laminate; Including, the first layer is located between the second layer and the third layer; the density of the first layer is greater than the density of the second layer and the density of the third layer; In the step of forming the laminate, the first layer is formed by atomic layer deposition.

[0009] This method of manufacturing a sample for spatial resolution measurement makes it possible to manufacture a sample that allows measurement of spatial resolution in the range of 0.5 nm to 5 nm.

[0010] One aspect of the method for measuring spatial resolution according to the present invention includes: preparing a sample for spatial resolution measurement; taking a transmission electron microscope image of the spatial resolution measurement sample in a transmission electron microscope; measuring the spatial resolution of the transmission electron microscope using the transmission electron microscope image; The spatial resolution measurement sample is A substrate; a laminate formed on a substrate; Including, the laminate includes a first layer, a second layer, and a third layer; the first layer is located between the second layer and the third layer; the density of the first layer is greater than the density of the second layer and the density of the third layer; The thickness of the first layer is 0.5 nm or more and 5 nm or less, In the step of measuring the spatial resolution, In the transmission electron microscope image, the thickness of the first layer is measured.

[0011] Such a method for measuring spatial resolution makes it possible to measure the spatial resolution of a transmission electron microscope in the range of 0.5 nm to 5 nm. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a cross-sectional view schematically showing a sample for measuring spatial resolution. [Figure 2] 10 is a flowchart showing an example of a method for manufacturing a sample for spatial resolution measurement. [Figure 3] 1A to 1C are diagrams schematically showing a manufacturing process of a sample for measuring spatial resolution. [Figure 4] 1A to 1C are diagrams schematically showing a manufacturing process of a sample for measuring spatial resolution. [Figure 5] 1A to 1C are diagrams schematically showing a manufacturing process of a sample for measuring spatial resolution. [Figure 6] 1A to 1C are diagrams schematically showing a manufacturing process of a sample for measuring spatial resolution. [Figure 7] 1A to 1C are diagrams schematically showing a manufacturing process of a sample for measuring spatial resolution. [Figure 8] 10 is a flowchart showing an example of a method for measuring resolution using a spatial resolution measurement sample. [Figure 9] Results of STEM-EDS analysis of the sample for spatial resolution measurement. [Figure 10] TEM image of the sample used for spatial resolution measurement. [Figure 11] Measurement results of the thickness of the ruthenium layer on the sample used for spatial resolution measurement. DETAILED DESCRIPTION OF THE INVENTION

[0013] Preferred embodiments of the present invention will be described in detail below with reference to the drawings. Note that the embodiments described below do not unduly limit the content of the present invention as defined in the claims. Furthermore, not all of the configurations described below are necessarily essential components of the present invention.

[0014] 1. Sample for spatial resolution measurement First, a sample for measuring spatial resolution according to one embodiment of the present invention will be described with reference to the drawings. 1 is a cross-sectional view that schematically shows a spatial resolution measurement sample 10 (hereinafter simply referred to as "sample 10") according to this embodiment.

[0015] The sample 10 is a sample for a transmission electron microscope used to measure the spatial resolution (hereinafter simply referred to as "resolution") of the transmission electron microscope. The spatial resolution is the smallest distance at which two spatially separated points can be distinguished. The sample 10 has a thickness that allows observation with the transmission electron microscope. The thickness of the sample 10 is, for example, approximately 20 nm to 50 nm. Although not shown, the sample 10 is supported on a sample stage for the transmission electron microscope.

[0016] A transmission electron microscope is a device that irradiates a sample with an electron beam and detects the electron beam that has transmitted through the sample to obtain a transmission electron microscope image. Transmission electron microscopes include transmission electron microscopes (TEMs), which form a sample image using electrons that have transmitted through the sample, and scanning transmission electron microscopes (STEMs), which scan the sample with an electron beam and detect the electron beam that has transmitted through the sample to obtain a sample image (scanned image). Transmission electron microscopes also include dynamic TEMs (DTEMs), which obtain TEM images using single-shot photography, and ultrafast TEMs (UTEMs), which realize time-resolved TEM imaging using stroboscopic photography.

[0017] As shown in FIG. 1, the sample 10 includes a substrate 2 and a laminate 4.

[0018] The substrate 2 is, for example, a single-crystal silicon substrate. The substrate 2 is not limited to a silicon substrate, and may be a semiconductor substrate other than silicon, such as a SiC substrate, a GaAs substrate, or a GaN substrate. The thickness of the substrate 2 is, for example, 0.1 mm or more and 1 mm or less. The substrate 2 is, for example, a single-crystal substrate. By using a single-crystal substrate as the substrate 2, an electron beam can be incident along the zone axis of the substrate 2 when capturing a transmission electron microscope image of the sample 10.

[0019] The laminate 4 is formed on the substrate 2. The laminate 4 includes a first layer 40, a second layer 42, and a third layer 44. The second layer 42, the first layer 40, and the third layer 44 are stacked in this order from the substrate 2 side. That is, the first layer 40 is located between the second layer 42 and the third layer 44. The second layer 42 is located between the substrate 2 and the first layer 40.

[0020] The first layer 40 is a metal layer formed by atomic layer deposition (ALD). The first layer 40 is made of, for example, a metal with an atomic number of 40 or greater. The material of the first layer 40 is, for example, molybdenum, ruthenium, or platinum. By using molybdenum, ruthenium, or platinum as the material of the first layer 40, a smooth, continuous film can be formed by ALD. A continuous film is a film that is a single, continuous layer without any island-like or particulate portions. The film thickness of the first layer 40 is 0.5 nm or greater and 5 nm or less.

[0021] The second layer 42 has a lower density than the first layer 40. The material of the second layer 42 is, for example, silicon oxide. The second layer 42 is, for example, a natural oxide film formed by oxidizing the substrate 2. The second layer 42 may be a film formed by CVD (Chemical Vapor Deposition), thermal oxidation, or the like. The material of the second layer 42 is not limited to silicon oxide, and a film having a lower density than the first layer 40 can be used. The material of the second layer 42 may be, for example, aluminum oxide, silicon nitride, or carbon. The film thickness of the second layer 42 is, for example, 1 nm or more and 100 nm or less. The film thickness of the second layer 42 is not particularly limited as long as the first layer 40 can be formed on the second layer 42 as a smooth, continuous film.

[0022] The third layer 44 has a lower density than the first layer 40. The material of the third layer 44 is, for example, carbon. Note that the material of the third layer 44 is not limited to carbon, and a film having a lower density than the first layer 40 can be used. The material of the third layer 44 can be silicon oxide, aluminum oxide, or the like. Alternatively, the third layer 44 may be made of silicon nitride. The film thickness of the third layer 44 is, for example, several tens of nanometers to several hundreds of nanometers. The film thickness of the third layer 44 is not particularly limited. The material of the second layer 42 and the material of the third layer 44 may be the same or different.

[0023] In a transmission electron microscope, the resolution of the transmission electron microscope can be measured by measuring the film thickness of the first layer 40 of the sample 10. Since the film thickness of the first layer 40 is 0.5 nm or more and 5 nm or less, the sample 10 can be used to measure a resolution of 0.5 nm or more and 5 nm or less.

[0024] 2. Method for producing samples for spatial resolution measurements Next, a method for manufacturing a spatial resolution measurement sample according to this embodiment will be described with reference to the drawings. Fig. 2 is a flowchart showing an example of a method for manufacturing the sample 10. Figs. 3 to 7 are diagrams schematically showing the manufacturing steps of the sample 10.

[0025] First, as shown in FIG. 3, a substrate 2 is prepared (step S100). For example, a silicon wafer is prepared as the substrate 2. The main surface 3 of the silicon wafer used as the substrate 2 is, for example, a mirror-polished, smooth surface. The thickness of the silicon wafer used as the substrate 2 is 0.1 mm or more and 1 mm or less. It is desirable that the plane orientation of the main surface 3 of the silicon wafer is known. For example, the plane orientation of the main surface 3 is

[0100] . By using a single-crystal substrate with a known plane orientation in this way, an electron beam can be incident along the zone axis of the substrate 2 when measuring the resolution with a transmission electron microscope. This allows the electron beam to be incident perpendicular to the film thickness direction of the first layer 40, allowing the film thickness of the first layer 40 to be accurately measured in a transmission electron microscope image.

[0026] Next, the laminate 4 is formed on the substrate 2 (step S102).

[0027] Here, a natural oxide film of silicon with a thickness of about 1 nm to 3 nm is formed on the main surface 3 of the silicon wafer. This natural oxide film is referred to as the second layer 42. That is, the material of the second layer 42 is silicon oxide (SiO2).

[0028] 4, a first layer 40 is formed on the second layer 42. The first layer 40 is formed by atomic layer deposition (ALD). In ALD, the film is formed by repeating a cycle of adding material, purging (evacuating the chamber), adding oxygen (O2), and purging.

[0029] ALD allows for the deposition of atomic-level layers one by one, enabling the precise deposition of metal layers of 0.5 nm to 5 nm in thickness. ALD allows for the deposition of continuous films by adjusting deposition conditions such as the vacuum level and other chamber conditions, the type of material, and the growth substrate. By using molybdenum, ruthenium, or platinum as the material for the first layer 40, the first layer 40 can be easily deposited as a smooth, continuous film by ALD.

[0030] Next, as shown in FIG. 5, the substrate 2 on which the second layer 42 and the first layer 40 have been formed is cleaved into pieces of approximately 10 mm square and introduced into a focused ion beam system (FIB). Next, a third layer 44 is formed on the first layer 40. The third layer 44 is, for example, a carbon film, and is formed by ion beam deposition using the FIB. Ion beam deposition is a technique in which an organic gas is sprayed onto the sample surface while an ion beam is irradiated, causing secondary electrons to react with the organic gas and forming a film locally. Through the above steps, the laminate 4 can be formed.

[0031] After forming the laminate 4 on the substrate 2 by depositing the third layer 44 on the first layer 40 by vapor deposition, sputtering, CVD, or the like, the substrate 2 on which the laminate 4 has been formed is cleaved and introduced into the FIB. That's fine.

[0032] Next, the substrate 2 on which the laminate 4 is formed is thinned to prepare a thin-film sample that can be observed with a transmission electron microscope (step S104). For example, first, as shown in FIG. 6, a sample block 20 is cut out from the substrate 2 on which the laminate 4 is formed using an FIB. Next, the cut-out sample block 20 is picked up using a pickup probe of the FIB and fixed to a sample stage 30 for the transmission electron microscope as shown in FIG. 7. The sample stage 30 is, for example, a grid for FIB processing. Next, the sample block 20 fixed to the sample stage 30 is thinned. For example, using an FIB, the substrate 2 on which the laminate 4 is formed is thinned to a thickness that allows an electron beam of several kV to several hundred kV to pass through. This allows the sample 10 to be prepared.

[0033] In the step of preparing the thin film sample, the substrate 2 on which the laminate 4 is formed may be sliced ​​by FIB to prepare a thin film sample, and then the thin film sample may be picked up and fixed to the sample stage 30. Alternatively, the substrate 2 on which the laminate 4 is formed may be sliced ​​by ion milling using an ion slicer (registered trademark) or the like that processes a sample with an argon ion beam.

[0034] Through the above steps, the sample 10 can be produced.

[0035] Although the above description has been given of a case where a silicon substrate is used as the substrate 2, the sample 10 can be manufactured in the same manner even when other semiconductor substrates are used.

[0036] Although the above description has been given of the case where the second layer 42 is a natural oxide film, the second layer 42 is not limited to a natural oxide film. For example, the second layer 42 may be formed on the substrate 2 after removing a natural oxide film formed on the substrate 2.

[0037] For example, first, the native oxide film on the substrate 2 is removed by wet etching using hydrofluoric acid or reduction using hydrogen plasma. Next, the substrate 2 from which the native oxide film has been removed is oxidized using a mixed solution of sulfuric acid and hydrogen peroxide to form a silicon oxide film. Through these steps, the second layer 42 made of silicon oxide can be formed. Note that the second layer 42 may also be formed on the substrate 2 from which the native oxide film has been removed by thermal oxidation, sputtering, CVD, or the like. Alternatively, a layer made of a material other than silicon oxide may be formed as the second layer 42 by vapor deposition, sputtering, CVD, or the like.

[0038] 3. Spatial resolution measurement Next, a method for measuring the resolution using a spatial resolution measurement sample will be described. Fig. 8 is a flowchart showing an example of the method for measuring the resolution using a sample 10.

[0039] First, the sample 10 is prepared (step S200). The thickness of the first layer 40 of the sample 10 is measured in advance using a transmission electron microscope with calibrated magnification.

[0040] Next, the sample 10 is introduced into a transmission electron microscope, and a transmission electron microscope image is taken (step S202). To take an image of the sample 10, first, the zone axis of the substrate 2 is aligned with the optical axis of the optical system of the transmission electron microscope so that the electron beam is incident along the zone axis of the substrate 2. Next, an electron beam is incident along the zone axis of the substrate 2, and a transmission electron microscope image of the sample 10 is taken.

[0041] The transmission electron microscope images to be captured are various types of transmission electron microscope images obtained by a transmission electron microscope. Such transmission electron microscope images include TEM images, in which a sample is irradiated with an electron beam and an image of the sample is formed using electrons transmitted through the sample, and STEM images, which are obtained by detecting electrons transmitted through the sample while scanning the sample with an electron beam. The STEM image may be a bright field STEM image (STEM-BF) or a dark field STEM image (STEM-DF). Such transmission electron microscope images may be TEM (dark field TEM) images. Such transmission electron microscope images also include TEM images taken with a DTEM and TEM images taken with a UTEM.

[0042] Next, the resolution of the transmission electron microscope is measured using the captured transmission electron microscope image (step S204). The resolution is measured by measuring the film thickness of the first layer 40. The film thickness of the first layer 40 is measured, for example, by obtaining an intensity profile in the thickness direction of the first layer 40 in the transmission electron microscope image and measuring the film thickness from the intensity profile. If the transmission electron microscope image is a grayscale image, the intensity is represented by the pixel value of each pixel in the grayscale image. An intensity profile is obtained in the thickness direction of the first layer 40 in the laminate 4, and the full width at half maximum (FWHM) of the intensity is determined. This full width at half maximum of the intensity is defined as the resolution.

[0043] In TEM images and STEM-BF images, the higher the density, the darker the observed object. Therefore, in TEM images and STEM-BF images, the dark first layer 40 is observed as being sandwiched between the bright second layer 42 and the bright third layer 44. Therefore, the film thickness of the first layer 40 can be accurately measured in TEM images and STEM-BF images.

[0044] Furthermore, in a STEM-DF image, the higher the density, the brighter the observed image. Therefore, in a STEM-DF image, the bright first layer 40 is observed as being sandwiched between a dark second layer 42 and a dark third layer 44. Therefore, in a STEM-BF image, the film thickness of the first layer 40 can be accurately measured. In this way, the film thickness of the first layer 40 can be accurately measured in various transmission electron microscope images.

[0045] For example, when the first layer 40 is made of ruthenium (Ru), the second layer 42 is made of silicon oxide (SiO2), and the third layer 44 is made of carbon (C), the density of the first layer 40 is 12.41 g / cm 3 and the density of the second layer 42 is 2.65 g / cm 3 and the density of the third layer 44 is 1.8 g / cm 3In this way, by increasing the difference in density between the first layer 40 and the second layer 42, and the difference in density between the first layer 40 and the third layer 44, it is possible to increase the difference in contrast between the first layer 40 and the second layer 42 and the difference in contrast between the first layer 40 and the third layer 44 in various transmission electron microscope images. This allows the film thickness of the first layer 40 to be measured accurately.

[0046] Through the above steps, the resolution of the transmission electron microscope can be measured.

[0047] 4. Effects The spatial resolution measurement sample 10 includes a substrate 2 and a stack 4 formed on the substrate 2. The stack 4 also includes a first layer 40, a second layer 42, and a third layer 44. The first layer 40 is located between the second layer 42 and the third layer 44, the density of the first layer 40 is greater than the density of the second layer 42 and the density of the third layer 44, and the film thickness of the first layer 40 is 0.5 nm or more and 5 nm or less. Therefore, with the sample 10, a resolution in the range of 0.5 nm or more and 5 nm or less can be measured using a transmission electron microscope.

[0048] To measure a resolution of 0.5 nm to 5 nm using a transmission electron microscope, a sample with a structure of 0.5 nm to 5 nm is required. However, no samples capable of measuring a resolution of 0.5 nm to 5 nm exist in nature. Therefore, a known method for measuring resolution is to disperse gold nanorods on a microgrid and use the voids that form by chance. However, even if gold nanorods are dispersed on a microgrid, it is unlikely that voids of 0.5 nm to 5 nm exist, making it difficult to find these voids using a transmission electron microscope. Furthermore, this method has low reproducibility.

[0049] In the spatial resolution measurement sample 10, the resolution can be measured in the range of 0.5 nm to 5 nm by measuring the film thickness of the first layer 40. In the sample 10, the first layer 40 is formed over the entire sample 10, making it easy to find the field of view for measurement. Therefore, in the sample 10, the resolution can be measured more easily than when measuring the resolution using the gold nanorods described above.

[0050] Furthermore, in the spatial resolution measurement sample 10, the density of the first layer 40 is greater than the densities of the second layer 42 and the third layer 44, making it easy to confirm the first layer 40 in various transmission electron microscope images. Therefore, in the sample 10, the film thickness of the first layer 40 can be accurately measured, and the resolution can be accurately measured.

[0051] In the spatial resolution measurement sample 10, the material of the first layer 40 is molybdenum, ruthenium, or platinum. Therefore, in a transmission electron microscope image, the difference in contrast between the first layer 40 and the second layer 42 and the difference in contrast between the first layer 40 and the third layer 44 can be increased. Therefore, in the sample 10, the first layer 40 is easily visible in a transmission electron microscope, allowing the film thickness of the first layer 40 to be accurately measured, and the resolution to be accurately measured. Furthermore, by using molybdenum, ruthenium, or platinum as the first layer 40, the first layer 40 can be formed into a smooth, continuous film by ALD.

[0052] In the spatial resolution measurement sample 10, the first layer 40 is a continuous film. Therefore, in the sample 10, the film thickness of the first layer 40 can be measured accurately.

[0053] In the spatial resolution measurement sample 10, the substrate 2 is a single crystal semiconductor substrate. Therefore, in the sample 10, an electron beam can be incident along the zone axis of the single crystal semiconductor substrate, and the film thickness of the first layer 40 can be measured accurately.

[0054] In the spatial resolution measurement sample 10, the material of the second layer 42 is silicon oxide, aluminum oxide, silicon nitride, or carbon, and the material of the third layer 44 is silicon oxide, aluminum oxide, silicon nitride, or carbon. Therefore, in the transmission electron microscope image of the sample 10, the difference in contrast between the first layer 40 and the second layer 42 and the difference in contrast between the first layer 40 and the third layer 44 can be increased.

[0055] In the spatial resolution measurement sample 10, the second layer 42 is located between the substrate 2 and the first layer 40, and the material of the second layer 42 is silicon oxide, and the material of the third layer 44 is carbon. Therefore, in the transmission electron microscope image of the sample 10, the difference in contrast between the first layer 40 and the second layer 42 and the difference in contrast between the first layer 40 and the third layer 44 can be made large.

[0056] The method for manufacturing the spatial resolution measurement sample 10 includes the steps of forming a stack 4 including a first layer 40, a second layer 42, and a third layer 44 on a substrate 2, and thinning the stack 4. The first layer 40 is located between the second layer 42 and the third layer 44, and the density of the first layer 40 is greater than the densities of the second layer 42 and the third layer 44. In the step of forming the stack 4, the first layer 40 is formed by atomic layer deposition. Therefore, in the method for manufacturing the sample 10, the first layer 40 is formed using ALD, and therefore the first layer 40 can be formed with a thickness of 0.5 nm to 5 nm with high accuracy. Therefore, the method for manufacturing the sample 10 can manufacture a sample capable of measuring with a resolution of 0.5 nm to 5 nm.

[0057] In the method for manufacturing the spatial resolution measurement sample 10, the first layer 40 is formed to a film thickness of 0.5 nm or more and 5 nm or less in the step of forming the stacked body 4. Therefore, the method for manufacturing the sample 10 can manufacture a sample that can be measured with a resolution of 0.5 nm or more and 5 nm or less.

[0058] In the method for manufacturing the spatial resolution measurement sample 10, the material of the first layer 40 is molybdenum, ruthenium, or platinum. Therefore, in the method for manufacturing the sample 10, the first layer 40 is formed using ALD, whereby the first layer 40 can be formed as a smooth, continuous film.

[0059] In the method for manufacturing the spatial resolution measurement sample 10, the first layer 40 is formed as a continuous film in the step of forming the stack 4. Therefore, the method for manufacturing the sample 10 can manufacture the sample 10 in which the length of the first layer 40 can be measured accurately.

[0060] In the method for manufacturing the spatial resolution measurement sample 10, the second layer 42 is located between the substrate 2 and the first layer 40, and the second layer 42 is a native oxide film formed on the substrate 2. Therefore, in the method for manufacturing the sample 10, the first layer 40 formed on the second layer 42 can be smoothed.

[0061] The method for measuring spatial resolution includes the steps of preparing a sample 10, capturing a transmission electron microscope image of the sample 10 using a transmission electron microscope, and measuring the resolution of the transmission electron microscope using the transmission electron microscope image. The sample 10 also includes a substrate 2 and a stack 4 formed on the substrate 2. The stack 4 also includes a first layer 40, a second layer 42, and a third layer 44. The first layer 40 is located between the second layer 42 and the third layer 44, and the density of the first layer 40 is greater than the densities of the second layer 42 and the third layer 44, and the film thickness of the first layer 40 is 0.5 nm or more and 5 nm or less. The step of measuring the resolution also includes measuring the film thickness of the first layer 40 in the transmission electron microscope image. Therefore, the resolution measurement method can measure the resolution of the transmission electron microscope in the range of 0.5 nm or more and 5 nm or less.

[0062] 5. Variations The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the present invention.

[0063] In the above-described embodiment, the first layer 40 is a continuous film, but the first layer 40 does not have to be a continuous film. The first layer 40 may be a film made up of connected particles of approximately 0.5 nm to 5 nm. For example, by controlling the film formation conditions of the atomic layer deposition method, the first layer 40 can be made into a film made up of connected particles. When the first layer 40 is a film made up of connected particles, the resolution can be measured by measuring the particle diameters in various transmission electron microscope images.

[0064] Furthermore, in the above-described embodiment, the second layer 42 is located between the substrate 2 and the first layer 40, but the second layer 42 does not have to be located between the substrate 2 and the first layer 40. For example, after removing a native oxide film from the substrate 2, the first layer 40 may be formed directly on the substrate 2 by atomic layer deposition.

[0065] 6. Experimental Example The present invention will be specifically explained below by way of experimental examples, but the present invention is not limited to the following experimental examples.

[0066] 6.1. Conditions The conditions for producing the sample for measuring spatial resolution are as follows.

[0067] Substrate: Silicon wafer, 2-inch diameter, 200 μm thick, surface orientation

[0100] Sample structure: Carbon / Ruthenium / Natural oxide film (SiO2) / Silicon (single crystal) Ruthenium deposition method: atomic layer deposition Ruthenium deposition equipment: ALK-600 (manufactured by Technofine Co., Ltd.) Ruthenium precursor: Carish (dicarbonyl-bis(5-methyl-2,4-hexanediketonato) Ru(II), Ru(IHD)2(CO)2 (Tanaka Kikinzoku Kogyo Co., Ltd.), oxygen (O2) Number of ALD cycles: 7 cycles Carbon film deposition method: Ion beam deposition using FIB

[0068] The observation conditions for the sample for measuring spatial resolution in the transmission electron microscope are as follows:

[0069] Equipment: JEM-ARM200F (manufactured by JEOL Ltd.) Accelerating voltage: 200 kV Electron microscope images: TEM, STEM-DF Elemental analysis: STEM-EDS (energy dispersive X-ray spectroscopy)

[0070] 6.2. Results Figure 9 shows the results of STEM-EDS analysis of the spatial resolution measurement sample. In the STEM-EDS analysis, electrons were incident along the zone axis of the silicon substrate of the spatial resolution measurement sample.

[0071] As shown in Figure 9, a layered structure of carbon / ruthenium / native oxide film / silicon was confirmed in the spatial resolution measurement sample.

[0072] The results shown in Figure 9 confirm that the ruthenium was not a continuous film but rather a film of linked particles. By changing the state of the film formation equipment, film formation conditions, and substrate state, it is possible to form ruthenium into a film of linked particles or a continuous film with a uniform thickness.

[0073] Figure 10 is a TEM image of the sample used for spatial resolution measurement. The TEM image shown in Figure 10 clearly confirms the layered structure of carbon / ruthenium / native oxide film / silicon. In particular, the ruthenium layer was clearly visible due to the large contrast differences between carbon and ruthenium, and between the native oxide film and ruthenium.

[0074] Figure 11 shows the measurement results of the ruthenium film thickness. Figure 11 shows the intensity profile in the film thickness direction of the ruthenium layer. In the intensity profile, the vertical axis represents intensity (pixel value) and the horizontal axis represents distance (nm).

[0075] The thickness of the ruthenium layer was determined by creating an intensity profile in the thickness direction of the ruthenium layer from the TEM image shown in Figure 10 and calculating the full width at half maximum of the intensity. In other words, the full width at half maximum of the intensity was taken as the thickness of the ruthenium layer. In this way, the thickness of the ruthenium layer was measured from the TEM image, and the thickness was found to be 1.8 nm.

[0076] The results shown in Figures 10 and 11 confirm that a metal layer fabricated using ALD can be measured with a resolution of approximately 0.5 nm to 5 nm. Furthermore, as shown in Figure 10, the ruthenium layer covers the entire fabricated sample, making it easy to find the field of view for length measurement. Furthermore, by irradiating the electron beam along the silicon zone axis, it was confirmed that the thickness of the ruthenium layer can be accurately measured.

[0077] The above-described embodiment and modifications are merely examples, and the present invention is not limited to these. For example, the embodiments and modifications can be combined as appropriate.

[0078] The present invention is not limited to the above-described embodiments, and various modifications are possible. For example, the present invention includes configurations that are substantially identical to the configurations described in the embodiments. A substantially identical configuration means, for example, a configuration with the same function, method, and result, or a configuration with the same purpose and effect. The present invention also includes configurations in which non-essential parts of the configurations described in the embodiments are replaced. The present invention also includes configurations that achieve the same effects or purposes as the configurations described in the embodiments. The present invention also includes configurations in which publicly known technology is added to the configurations described in the embodiments. [Explanation of symbols]

[0079] 2...substrate, 3...main surface, 4...laminated body, 10...spatial resolution measurement sample, 20...sample block, 30...sample stage, 40...first layer, 42...second layer, 44...third layer

Claims

1. A sample for measuring spatial resolution of a transmission electron microscope, A substrate; a laminate formed on the substrate; Including, the laminate includes a first layer, a second layer, and a third layer; the first layer is located between the second layer and the third layer; the density of the first layer is greater than the density of the second layer and the density of the third layer; A sample for spatial resolution measurement, wherein the film thickness of the first layer is 0.5 nm or more and 5 nm or less.

2. In claim 1, The sample for spatial resolution measurement, wherein the first layer is a continuous film.

3. In claim 1, The substrate is a single-crystal semiconductor substrate.

4. In claim 1, the second layer is made of silicon oxide, aluminum oxide, silicon nitride, or carbon; A sample for spatial resolution measurement, wherein the material of the third layer is silicon oxide, aluminum oxide, silicon nitride, or carbon.

5. In claim 1, the second layer is located between the substrate and the first layer; the second layer is made of silicon oxide; A sample for spatial resolution measurement, wherein the material of the third layer is carbon.

6. In any one of claims 1 to 5, The material of the first layer is molybdenum, ruthenium, or platinum.

7. A method for manufacturing a sample for measuring spatial resolution of a transmission electron microscope, comprising: forming a laminate including a first layer, a second layer, and a third layer on a substrate; Slicing the laminate; Including, the first layer is located between the second layer and the third layer; the density of the first layer is greater than the density of the second layer and the density of the third layer; In the step of forming the stack, the first layer is formed by atomic layer deposition.

8. In claim 7, In the step of forming the laminate, the first layer is formed to a thickness of 0.5 nm or more and 5 nm or less.

9. In claim 7, A method for manufacturing a sample for spatial resolution measurement, wherein in the step of forming the laminate, the first layer is formed as a continuous film.

10. In claim 7, the second layer is located between the substrate and the first layer; The method for manufacturing a sample for spatial resolution measurement, wherein the second layer is a native oxide film formed on the substrate.

11. In claim 7, the second layer is located between the substrate and the first layer; In the step of forming the laminate, A method for producing a sample for spatial resolution measurement, comprising removing a native oxide film formed on the substrate, and forming the second layer on the substrate from which the native oxide film has been removed.

12. In any one of claims 7 to 11, A method for manufacturing a sample for spatial resolution measurement, wherein the material of the first layer is molybdenum, ruthenium, or platinum.

13. preparing a sample for spatial resolution measurement; taking a transmission electron microscope image of the spatial resolution measurement sample in a transmission electron microscope; measuring the spatial resolution of the transmission electron microscope using the transmission electron microscope image; The spatial resolution measurement sample is A substrate; a laminate formed on the substrate; Including, the laminate includes a first layer, a second layer, and a third layer; the first layer is located between the second layer and the third layer; the density of the first layer is greater than the density of the second layer and the density of the third layer; The first layer has a thickness of 0.5 nm or more and 5 nm or less, In the step of measuring the spatial resolution, a method for measuring spatial resolution, the method comprising measuring a film thickness of the first layer in the transmission electron microscope image;

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