Observation device for permeation diffusion path of observation target gas, measurement method of observation target gas, point defect position detection device, point defect position detection method, and observation sample

Abstract

The present application includes a scanning electron microscope (15), an observation object ion detection unit (20) that detects an observation object ion, an observation object gas supply unit (19) that supplies an observation object gas to an observation object gas pipe (14) connected to the back surface side of a sample (17), a diaphragm type sample holder (12) that can mount the sample (17) as a diaphragm that separates an analysis chamber (11) and the observation object gas pipe (14), and a control unit (50) that acquires a SEM image while supplying the observation object gas and causing the sample to generate stress by a differential pressure between the analysis chamber (11) and the observation object gas pipe (14), detects the observation object gas that diffuses into the sample and escapes to the surface by electron excitation detachment, and acquires an ESD image of the observation object ion, whereby it is possible to investigate the mechanism of a deterioration phenomenon such as a structure material embrittlement phenomenon caused by the observation object gas.

Description

TECHNICAL FIELD

[0001] The present application relates to a permeation diffusion path observation device and observation method for an observation target gas such as hydrogen emitted from a sample, capable of exciting the observation target gas using scanning electron of an electron microscope and imaging the region on a solid surface where the observation target gas emitted from the solid surface exists, a point defect position detection device and point defect position detection method using the same, and an observation sample used therein. BACKGROUND

[0002] Hydrogen embrittlement in structural materials is a major issue and is an increasingly important research field as the field of hydrogen utilization develops. Hydrogen has only one electron, so it cannot be detected by electron spectroscopy or energy dispersion X-ray spectroscopy (hereinafter referred to as EDX), and methods for indirectly confirming the presence of hydrogen such as a method for vibration spectroscopy of hydrogen and other atoms, a method for determination by nuclear reaction, a hydrogen microprinting method (silver decoration, etc.), and the like are known.

[0003] Methods for observing the distribution of hydrogen emitted from the inside of a solid to the surface include a nuclear reaction method, a hydrogen microprinting method (silver decoration), and the like, but none of them can dynamically track hydrogen diffusing inside a solid.

[0004] A hydrogen permeation position detection device is a device that excites hydrogen emitted from a sample using scanning electron of an electron microscope to cause it to desorb and is imaged, and is one type of operando hydrogen microscope (see Patent Documents 1 and 2). An operando hydrogen microscope is a measurement device that permeates a hydrogen permeation material and acquires a released portion thereof as a two-dimensional image. In the method for visualizing permeated hydrogen in the conventional operando hydrogen microscope, an observation sample is fixed to a partition wall position of a vacuum container, and a low vacuum side of the sample is exposed to hydrogen gas at an appropriate partial pressure, whereby hydrogen diffused into the solid is observed as emitted hydrogen on the high vacuum side.

[0005] The cause of hydrogen embrittlement is hydrogen absorption caused by corrosion, welding, pickling, plating, and the like. The damage caused by this hydrogen absorption is called "delayed fracture". It is said that hydrogen embrittlement damage is easy to occur at grain boundaries, sites where tensile stress is applied, and portions where stress is concentrated. Research on hydrogen embrittlement has been conducted for a long time, and many studies are still ongoing. Many research topics on hydrogen materials and hydrogen embrittlement aim to explore the behavior of hydrogen under strain and stress in structural materials. However, the factors that cause embrittlement are intricately intertwined with materials, structures, stress, and environment and cannot be separated, and the essence is still unclear (see Non-Patent Documents 1 and 2).

[0006] In addition, an electron stimulated desorption method (hereinafter referred to as an ESD method) is a method of performing surface analysis by ionizing and desorbing adsorbed atoms by irradiation of electrons, and is a publicly known method in the field of surface analysis. If the ESD method is used, hydrogen can be directly observed in real time (see Non-Patent Literature 3 and Non-Patent Literature 4).

[0007] On the other hand, by using the ESD method, it is possible to visualize the positional information of hydrogen remaining on the surface, but if the hydrogen has completely desorbed, it is not possible to continue the measurement, and thus it is not suitable for measuring the amount of hydrogen evolution present in a small amount in steel.

[0008] Prior Art Documents

[0009] Patent Documents

[0010] Patent Document 1: Japanese Patent Application Publication No. 2017-187457;

[0011] Patent Document 2: Japanese Patent Application Publication No. 2019-145255.

[0012] Non-Patent Documents

[0013] Non-Patent Document 1: Takai Kenichi, “Importance and New Progress of Analysis Techniques for Overcoming Hydrogen Embrittlement of Metal Materials”, SCAS NEWS, 2009-II, Vol. 30, pp. 3-6;

[0014] Non-Patent Document 2: Takai Kenichi, “Base Plate Construction and Latest Progress in Research on Hydrogen Embrittlement of Steel Materials”, Sanyo Technical Report, Vol. 22, 2015, No. 1, pp. 14-20;

[0015] Non-Patent Document 3: Tabara Akiko et al., “Effect of Surface Processing of Stainless Steel on Hydrogen Release”, J. Vac. Soc. Jpn., Vol. 57, No. 1, pp. 23-26, 2014;

[0016] Non-Patent Document 4: Miyashita Naoyuki et al., “Observation of Distribution of Permeated Hydrogen on the Surface of Stainless Steel”, J. Vac. Soc. Jpn., Vol. 58, No. 10, pp. 387-391, 2015. SUMMARY

[0017] PROBLEMS TO BE SOLVED BY THE INVENTION

[0018] Hydrogen embrittlement damage easily occurs at grain boundaries, sites where tensile stress is applied, and portions where stress is concentrated, but in the conventional hydrogen permeation and diffusion path observation device, it is difficult to analyze the effects of such stress.

[0019] The present application is to solve the above problems, and aims to provide a permeation diffusion path observation device for an observation target gas and a measurement method for an observation target gas, which can separate the influence of stress and observe the observation target gas by operating stress, which is a factor that causes hydrogen embrittlement and the like, as an independent parameter, and can also be applied to, for example, the mechanism exploration of embrittlement phenomena and deterioration phenomena of a structural material caused by a hydrogen-containing observation target gas such as hydrogen embrittlement and the like.

[0020] In addition, another object of the present application is to provide a point defect position detection device and a point defect position detection method using such a device and a method. Furthermore, another object is to provide an observation sample suitable for use in these devices and methods.

[0021] Means for solving the problem

[0022] The present inventors and others have continued to conduct in-depth research on a device and a method suitable for hydrogen embrittlement mechanism exploration, and have conceived a mechanism that can apply stress and introduce strain to a sample measured using an in-situ hydrogen microscope. Specifically, a mechanism has been conceived in which a noble gas is mixed as a pressurized gas in a gas line of a hydrogen or the like observation target gas, and in a state in which the pressure (partial pressure) of the observation target gas is fixed, a sample is pressed from the back side in a non-contact manner using the total pressure (the sum of the observation target gas pressure and the noble gas pressure) without using a pressure head or the like.

[0023] The permeation diffusion path observation device for an observation target gas of the present application includes: a scanning electron microscope having an analysis chamber, an electron source, and a secondary electron detector, the analysis chamber housing a sample, the electron source irradiating an electron beam to the sample, and the secondary electron detector detecting secondary electrons generated by the electron beam irradiated to the sample; an observation target ion detection section that detects observation target ions generated by the electron beam irradiated to the sample from the electron source; an observation target gas supply section that supplies an observation target gas to an observation target gas pipe connected to the back side of the sample; a diaphragm-type sample holder that mounts the sample as a diaphragm that separates the analysis chamber and the observation target gas pipe; and a control section that acquires a SEM (Scanning Electron Microscope) image of secondary electrons generated from the sample by scanning of the electron beam, acquires an ESD image of the observation target ions detected by the observation target ion detection section in synchronization with the scanning of the electron beam in a state in which stress is generated in the sample by a differential pressure generated between the analysis chamber and the observation target gas pipe by supplying the observation target gas from the observation target gas supply section, changes the observation target gas diffused into the sample from the back side of the sample and escaping to the surface of the sample into the observation target ions by electron excitation detachment by the electron beam, and changes the observation target gas diffused into the sample from the back side of the sample and escaping to the surface of the sample into the observation target ions by electron excitation detachment by the electron beam.

[0024] The permeation diffusion path observation device for an observation target gas according to the present application preferably includes a pressurized gas supply unit that supplies pressurized gas to the observation target gas pipe, and generates a pressure difference by the pressurized gas supplied from the pressurized gas supply unit.

[0025] In the permeation diffusion path observation device for an observation target gas according to the present application, the observation target ion detection unit can include a collection mechanism that collects the observation target ions generated from the sample surface, an ion energy resolution unit that is provided at an upper portion of the collection mechanism, that the observation target ions collected by the collection mechanism are incident to, and that removes substances other than the observation target ions, and an ion detector that detects the observation target ions that have passed through the ion energy resolution unit and outputs to the control unit, and the collection mechanism can have a mesh or a lens fixed around the sample, and be configured to collect the observation target ions and make the observation target ions incident to the ion detector by applying a predetermined voltage between the mesh or the lens and the ground. The diaphragm-type sample holder can include a sample mounting portion having an open window, and the sample can be mounted to the sample mounting portion in a state of plugging the open window. The sample can be fixed to the diaphragm-type sample holder.

[0026] The observation target gas is preferably any one of molecules, atoms, and ions of any one of hydrogen, deuterium, helium, oxygen, nitrogen, water, or a gas related to the sample production or the sample use purpose, any one of molecules, atoms, and ions of a plurality of gases therefrom. The pressurized gas is preferably at least one selected from the group consisting of helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), radon (Rn), and nitrogen (N).

[0027] The observation sample mounted to the permeation diffusion path observation device according to the present application preferably includes a thin-walled diaphragm portion that generates stress by a pressure difference at the time of observation, and a thick-walled peripheral portion formed around the diaphragm portion, and the observation sample is mounted to the diaphragm-type sample holder as a diaphragm that separates the analysis chamber and the observation target gas pipe. The sample can be a metal flat plate, a plate material that thins a welded portion of a metal, a plate material that thins a metal having a corrosion site, a ceramic plate, a polymer plate, or a plate material composed of a composite material thereof. The sample is preferably formed in a circular shape or a polygonal shape, and the size and the thickness of the diaphragm portion and the position of the diaphragm portion in the thickness direction of the peripheral portion are set so that tensile stress or compressive stress is generated on the surface of the analysis chamber side and the surface of the observation target gas pipe side by the pressure difference at the time of observation.

[0028] In a method of measuring an observation object ion of a permeation sample using the permeation diffusion path observation device of the present application, a gas supply step of generating stress in the sample by a differential pressure generated between an analysis chamber and an observation object gas pipe by supplying an observation object gas from an observation object gas supply section, and an image acquisition step of acquiring a SEM image using secondary electrons generated from the sample by scanning of an electron beam, and converting the observation object gas diffused into the sample from the back surface of the sample and escaping to the surface of the sample into an observation object ion by electron excitation detachment by the electron beam, and acquiring an ESD image detected by an ion detection section in synchronization with the scanning of the electron beam, wherein in the image acquisition step, the position resolution of the ESD image is set to 50 nm or less and compared with the SEM image.

[0029] Preferably, the gas supply step includes a pressurized gas supply step of generating a differential pressure between the analysis chamber and the observation object gas pipe by supplying a pressurized gas from a pressurized gas supply section, and an observation object gas supply step of supplying the observation object gas from the observation object gas supply section.

[0030] In the gas supply step, the differential pressure can be generated by changing the pressure of the pressurized gas or the partial pressure of the observation object gas or both, sequentially changing the differential pressure and repeatedly performing the image acquisition step, and measuring the escaping behavior of the observation object gas with respect to the change in the differential pressure from the SEM image and the ESD image acquired each time.

[0031] The point defect position detection method of the present application is a method of performing point defect position detection using the measurement method of the observation object gas as described above.

[0032] The point defect position detection device of the present application includes the permeation diffusion path observation device of the observation object gas described above, and a point defect position extraction section that detects the point defect position of the sample from the SEM image and the ESD image of the sample. The point defect position detection method of the present application is a method of detecting atoms or molecules leaked from the inside or the back surface of the sample via a point defect as ions using such a point defect position detection device, including the steps of preparing a sample, arranging the sample on a diaphragm type sample holder, acquiring a SEM image of the sample, acquiring an ESD image of the sample, and determining the point defect position of the sample by comparing the SEM image and the ESD image of the sample.

[0033] Effects of the Invention

[0034] According to the present application, there is provided a micro observation device and a measurement method suitable for observing the behavior of hydrogen permeation and diffusion in a state where a strain and stress are generated in a solid of a sample to be observed. In detail, the permeation and diffusion path observation device according to the present application mounts a sample determined by an in-situ hydrogen microscope as a diaphragm in an analysis chamber, generates a desired stress by a differential pressure, and thus can handle a stress, which is a factor that causes hydrogen embrittlement, as an independent parameter. Therefore, according to the present application, it is possible to separate the influence of the stress and detect a hydrogen embrittlement mechanism, for example. In addition, if the device of the present application is used, it is possible to observe the behavior of an observation target gas in a state where a strain and stress are applied to a solid surface, and it is possible to visualize the performance evaluation of a film having a sealing effect of an observation target gas and the behavior of a gas leaking from a minute structural defect present in the film, for example.

[0035] The measurement method of the observation target gas of the present application is suitable for the exploration of a more general deterioration phenomenon mechanism of a structural material caused by a hydrogen-containing observation target gas, for example. In addition, according to the point defect position detection device and the detection method thereof using the device and the measurement method of the present application, it is possible to detect a gas absorbed in a sample, a gas permeating from a point defect in a sample, for example, and non-destructive inspection of a material is effective. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 FIG. 1 is a diagram schematically showing the internal structure of a hydrogen permeation and diffusion path observation device as one type of permeation and diffusion path observation device of the observation target gas of the present application.

[0037] Figure 2 FIG. 2 is a partial cross-sectional view showing the relationship of a diaphragm type sample holder and a hydrogen pipe and the like connected to the diaphragm type sample holder.

[0038] Figure 3 FIG. 3 is a partial enlarged schematic view showing the relationship of a hydrogen ion detection portion in an analysis chamber and a diaphragm type sample holder and a hydrogen pipe and the like connected to the diaphragm type sample holder in the first embodiment.

[0039] Figure 4 FIG. 4 is a diagram showing the detection principle of a hydrogen ion generated by electron excitation and detachment when an electron beam is irradiated to a sample in the present application.

[0040] Figure 5 FIG. 5 is a block diagram showing the structure of a control portion of the present application.

[0041] Figure 6 FIG. 6 is a block diagram showing the structure of an electron excitation and detachment overall control portion.

[0042] Figure 7 FIG. 7 is a diagram showing the relationship of scanning of an electron beam and two-dimensional measurement of an ESD image.

[0043] Figure 8 is a flowchart of measuring a two-dimensional ESD image of an electron beam scan.

[0044] Figure 9A is a plan view of a sample 17A showing one example of a sample shape that is a stress analysis target of the present application.

[0045] Figure 9B is a sectional view of the sample 17A.

[0046] Figure 9C is a perspective view of the sample 17A.

[0047] Figure 10 is a plan view for explaining a stress distribution outline of the sample 17A.

[0048] Figure 11A is a graph showing a stress analysis result in a state where the differential pressure is 0.8 MPa in the cross section of the sample 17A.

[0049] Figure 11B is a graph showing a stress analysis result in a state where the differential pressure is 0.4 MPa in the cross section of the sample 17A.

[0050] Figure 11C is a graph showing a stress analysis result in a state where the differential pressure is 0.16 MPa in the cross section of the sample 17A.

[0051] Figure 11D is a graph showing a stress analysis result in a state where the differential pressure is 0.08 MPa in the cross section of the sample 17A.

[0052] Figure 12A is a plan view of a sample 17B showing another example of a sample shape that is a stress analysis target of the present application.

[0053] Figure 12B is a sectional view of the sample 17B.

[0054] Figure 12C is a perspective view of the sample 17B.

[0055] Figure 13A is one example of a shape and a real number used for stress calculation of the sample 17B.

[0056] Figure 13B is a graph showing a stress calculation result of the sample 17B.

[0057] Figure 13C is a schematic view of a strain of the sample 17B reflecting a calculation result of Figure 13B

[0058] Figure 14A ​This is a top view of specimen 17C, which is another example of the specimen shape that is the object of stress analysis in this invention.

[0059] Figure 14B This is a cross-sectional view of sample 17C.

[0060] Figure 14C This is a three-dimensional view of sample 17C.

[0061] Figure 15A This is an example of shape and real number used for stress calculation of specimen 17C.

[0062] Figure 15B This is a graph showing the stress calculation results for specimen 17C.

[0063] Figure 15C It reflects Figure 15B A schematic diagram of the strain of the 17C specimen calculated from the results.

[0064] Figure 16A This is a graph showing the stress calculation results of specimen 17D, which is another example of the specimen shape that is the object of stress analysis in this invention.

[0065] Figure 16B It reflects Figure 16A A schematic diagram of the 17D strain of the specimen calculated from the results.

[0066] Figure 17A This is a top view of specimen 17E, which is another example of the specimen shape that is the object of stress analysis in this invention.

[0067] Figure 17B This is a cross-sectional view of sample 17E.

[0068] Figure 17C This is a three-dimensional view of sample 17E.

[0069] Figure 18A This is an example of shape and real number used for stress calculation of specimen 17E.

[0070] Figure 18B This is a graph showing the stress calculation results for specimen 17E.

[0071] Figure 18C It reflects Figure 18B A schematic diagram of the strain of specimen 17E based on the calculated results.

[0072] Figure 19 This is a block diagram showing the structure of the control unit in the point defect location detection device of the present invention, which is capable of extracting stress application effects and point defect locations.

[0073] Figure 20is a flowchart of extracting a stress application effect from the measurement of the present application.

[0074] Figure 21 is a flowchart of extracting a stress application effect from the measurement of the present application. DETAILED DESCRIPTION

[0075] Hereinafter, an embodiment of the present application will be described in detail based on the drawings. In the following description, the case of hydrogen is exemplified as the observation target gas, but the present application is not limited thereto. As the observation target gas, any one of molecules, atoms, and ions from any one of deuterium, helium, oxygen, nitrogen, water, or a gas related to the purpose of use of a sample at the time of production of the sample, any one of molecules, atoms, and ions from a plurality of gases therefrom, and the like can be used.

[0076] (First Embodiment)

[0077] First, a hydrogen permeation diffusion path observation device, which is one type of permeation diffusion path observation device for an observation target gas, will be described. Figure 1 is a view schematically showing the structure of a hydrogen permeation diffusion path observation device 10 related to the first embodiment.

[0078] As shown in Figure 1 , the hydrogen permeation diffusion path observation device 10 is provided with a scanning electron microscope 15. The scanning electron microscope 15 is equipped with a sample 17, an analysis chamber 11 that houses an electron source 16 that irradiates an electron beam to the sample 17, and a secondary electron detector 18 that is provided to the analysis chamber 11 and detects secondary electrons generated by the electron beam irradiated to the sample 17. The hydrogen permeation diffusion path observation device 10 further includes a hydrogen ion detection section 20 that detects hydrogen ions generated by the electron beam irradiated from the electron source 16 to the sample 17, a hydrogen gas supply section 19 that supplies hydrogen to a hydrogen pipe 14 connected to the back surface side of the sample 17, a pressurized gas supply section 24 that supplies pressurized gas to the hydrogen pipe 14, a diaphragm type sample holder 12 that can mount the sample 17 in a manner to separate the analysis chamber 11 and the hydrogen pipe 14, and a control section 50.

[0079] The hydrogen gas supply section 19 is connected to the diaphragm type sample holder 12 via the hydrogen pipe 14 and a sample stage section 31. The pressurized gas supply section 24 is connected to the diaphragm type sample holder 12 via the hydrogen pipe 14 and the sample stage section 31. The pressurized gas is, for example, a noble gas such as helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), radon (Rn), or nitrogen.

[0080] The analysis chamber 11 is equipped with the sample stage section 31 that places the diaphragm type sample holder 12 and is connected to the hydrogen pipe section 14, a sample temperature measurement section 33 that measures the temperature of the sample 17, and a sample position adjustment section 34 that adjusts the position of the sample 17.

[0081] As Figure 1 indicated, a mass spectrometer 35 or the like that analyzes the residual elements in the analysis chamber 11 can also be provided. The mass spectrometer 35 is, for example, a quadrupole mass spectrometer. The analysis chamber 11 can also include an Auger electron spectrometer. With the Auger electron spectrometer, the amount of carbon or the like present on the surface of the sample 17 can be measured. Prior to acquiring the ESD image, the hydrogen, carbon or the like background present on the surface of the sample 17 can also be removed by irradiation of a sputtering source or electron beam provided in the analysis chamber 11.

[0082] The analysis chamber 11 is evacuated by a first vacuum exhaust portion 37. The first vacuum exhaust portion 37 is configured to include a vacuum pump such as a turbo molecular pump, not shown, and a gate valve, a vacuum gauge, and the like. The analysis chamber 11 is evacuated to a degree of vacuum at which a SEM image can be obtained, for example, 1.0 x 10 -7 Pa or less.

[0083] The front end of the hydrogen pipe 14 is connected to the diaphragm-type sample holder 12 on which the sample 17 is mounted via the flange of the sample stage portion 31, and can supply hydrogen to the back surface of the sample 17. The base end side is connected to the second vacuum exhaust portion 38 via the flange, pipe, stop valve, and the like. The hydrogen pipe 14 is evacuated by the second vacuum exhaust portion 38. The second vacuum exhaust portion 38 is configured to include a vacuum pump such as a turbo molecular pump, not shown, and a stop valve, a vacuum gauge, and the like. The second vacuum exhaust portion 38 evacuates the hydrogen pipe 14, the sample stage portion 31, and the diaphragm-type sample holder 12 to a prescribed degree of vacuum.

[0084] The hydrogen gas supply portion 19 is configured to include a hydrogen gas cylinder, not shown, a pressure regulator, a stop valve, a pressure gauge, and the like. After the hydrogen pipe 14, the sample stage portion 31, and the diaphragm-type sample holder 12 are evacuated to a prescribed degree of vacuum, the stop valve on the second vacuum exhaust portion 38 side can be closed. The prescribed degree of vacuum is, for example, 8.0 x 10 -4 Pa or less.

[0085] If the stop valve on the hydrogen gas supply portion 19 side is opened at the prescribed degree of vacuum, hydrogen gas is supplied from the hydrogen gas supply portion 19 to the hydrogen pipe 14. As a result, the back surface of the sample 17 is exposed to hydrogen via the sample stage portion 31 and the diaphragm-type sample holder 12. The hydrogen gas is preferably deuterium so that it can be easily distinguished from the hydrogen gas that remains in the analysis chamber 11 as background.

[0086] Figure 2is a partial cross-sectional view showing the relationship of the diaphragm-type sample holder 12 and the hydrogen piping 14 and the like connected to the diaphragm-type sample holder 12. The diaphragm-type sample holder 12 is provided with a flange portion 12a, and a sample mounting portion 12b connected to the upper portion of the flange portion 12a and having an open window W, and becomes a structure in which the open window W of the sample mounting portion 12b is plugged with a sample 17. The window frame area around the open window W of the diaphragm-type sample holder 12 abuts against the outer periphery of the sample 17. The interface of the window frame area around the open window W of the diaphragm-type sample holder 12 and the sample 17 is sealed using a general vacuum sealing method such as an elastomer seal, a metal gasket seal, or the like that can be vacuum sealed.

[0087] The flange portion 12a is constituted, for example, using a flanged single pipe of ICF 34 (international standard specification). In order to make the heat conduction good, the sample mounting portion 12b can be constituted using copper.

[0088] The sample 17 is held in the outer periphery by the sample fixing plate 13 at the upper portion of the sample mounting portion 12b of the diaphragm-type sample holder 12. Not only a single sample 17, but also a plurality of samples 17 can be mounted on the sample mounting portion 12b. The size of the sample 17 can be, for example, 16 mmφ in diameter and 1 mm in thickness, as long as it is a shape in which the window area of the open window W is plugged with the sample 17. This hydrogen permeation and diffusion path observation device 10 can measure the release of any one of a gas adsorbed, contained, or solid-solved in the sample 17 mounted on the sample mounting portion 12b, or an atom that becomes a gas constituent component.

[0089] In the present embodiment, the diaphragm-type sample holder 12 is provided together with the sample stage portion 31 between the analysis chamber 11 and the hydrogen piping 14. By mounting the sample 17 in a manner that plugs the open window W of the sample mounting portion 12b of this diaphragm-type sample holder 12, the sample 17 functions as a diaphragm that separates the analysis chamber 11 and the hydrogen piping 14. In the drawings, a case in which the sample 17 is mounted on the sample mounting portion 12b in a detachable manner is shown, but the sample 17 can also be fixed by welding in a manner that plugs the open window W of the sample mounting portion 12b. The sample 17 that is welded can be, for example, a thin plate constituted of steel or stainless steel. The measured portion thickness of the sample 17 provided as a diaphragm can be set to the same degree as the sample grain size, for example, about 100 to 300 μm, but it is preferable that an outer peripheral portion of 500 to 2000 μm be formed around it as a portion involved in welding.

[0090] Figure 3is a partial enlarged view showing the hydrogen ion detection section 20 inside the analysis chamber 11 and the diaphragm-type sample holder 12 and the hydrogen piping 14 and the like connected to the diaphragm-type sample holder 12 via the sample stage section 31. The hydrogen ion detection section 20 includes a collection mechanism 21 that collects hydrogen ions generated from the surface of the sample 17, an ion energy resolution section 22 that removes substances other than hydrogen ions, and an ion detector 23 that detects hydrogen ions that have passed through the ion energy resolution section 22.

[0091] The hydrogen ion detection section 20 detects hydrogen ions generated at the surface of the sample 17 by the ESD method. A two-dimensional image of hydrogen ions detected by scanning with an electron beam is also called an ESD image or an ESD map.

[0092] The sample stage section 31 is provided with a sample heating section 32 to promote diffusion of hydrogen with the temperature of the sample 17 as a temperature higher than room temperature. The temperature of the heated sample 17 is measured by a sample temperature measuring section 33 shown in Figure 1 As a temperature sensor used in this sample temperature measuring section 33, for example, a thermocouple composed of copper and constantan can be used. The thermocouple can also be connected to the sample 17 by welding. The lead wire of the thermocouple is connected to a lead wire extraction port 11a provided in the analysis chamber 11. The electromotive force generated at the thermocouple by the heating temperature of the sample 17 is measured by a voltmeter connected to the external terminal of the lead wire extraction port 11a, and the temperature of the sample 17 can be measured. A temperature adjustment mechanism that senses this voltage and feeds back to the heater current to maintain the temperature constant is provided. Here, the sample heating section 32 can also be provided in a portion other than the hydrogen piping 14.

[0093] The surface of the sample 17 held by the diaphragm-type sample holder 12 is exposed to the analysis chamber 11 side, and the back side is exposed to the hydrogen piping 14 side. The diaphragm-type sample holder 12 is fixed to the sample stage section 31 by a screw or the like. The sample 17 is heated by the sample heating section 32. The sample heating section 32 is composed of, for example, a halogen lamp.

[0094] A collection mechanism 21 for efficiently collecting escaping ions is provided near the surface side of the sample 17. The illustrated collection mechanism 21 is composed of, for example, a metal wire mesh, and is a mesh structure lens. Ions of the target gas, such as hydrogen ions, collected by the collection mechanism 21 are incident to the hydrogen ion detection section 20. The ion energy resolution section 22, for example, sorts hydrogen ions to be incident to the ion detector 23.

[0095] The ion energy resolving section 22 is configured by a cap-shaped metal electrode in a manner that the ion detector 23 is not directly opposed to the sample 17. The ion energy resolving section 22 can use a cylindrical or conical electrode. The ion energy resolving section 22 applies a proper positive voltage to the cylindrical electrode, and by an electric field, only ions of a target gas, for example, only hydrogen ions are guided to the ion detector 23, and light and electrons generated by irradiation of the electron beam to the sample 17 can be removed. The ion detector 23 can use, for example, a Ceratron (a secondary electron multiplier), a secondary electron multiplier tube.

[0096] (ESD)

[0097] Figure 4 is a view schematically showing detection of hydrogen ions 41 generated by electron stimulated desorption when the electron beam 16a is irradiated to the sample 17. As shown in Figure 4 , the analysis chamber 11 is partitioned from the hydrogen piping 14 and the sample stage section 31 with the sample 17 as a partition wall. That is, the sample 17 is installed between the analysis chamber 11 and the hydrogen piping 14 and the sample stage section 31 in a manner that the sample 17 becomes a diaphragm. In the analysis chamber 11, the electron beam 16a is irradiated to the surface of the sample 17, and the hydrogen ions 41 are generated from the sample 17.

[0098] The back surface side of the sample 17 is the hydrogen piping 14 and the sample stage section 31, and after being vacuumed, hydrogen is introduced at a prescribed pressure. The hydrogen piping 14 also functions as a vacuum container. The hydrogen introduced from the back surface side of the sample 17 to the inside of the sample 17 diffuses in the inside of the sample 17, reaches the surface side surface of the sample 17, and is released. That is, hydrogen, deuterium penetrates from the back surface side of the sample 17 to the surface. The hydrogen reaching the surface of the sample 17 is irradiated by the electron beam 16a. Thereby, the hydrogen ions 41 desorbed from the sample 17 by electron stimulated desorption (ESD) are desorbed from the sample 17, and are collected by the collection mechanism 21. The hydrogen ions 41 are detected by the hydrogen ion detection section 20.

[0099] (control section)

[0100] Figure 5 is a block diagram of the control section 50, Figure 6 is a block diagram showing the structure of the electron stimulated desorption overall control section 52.

[0101] As Figure 5As shown, the control unit 50 is configured to include: an overall electron microscope control unit 51, which controls the scanning electron microscope 15; and an overall electron excitation separation control unit 52, which controls the acquisition of ESD images. The overall electron microscope control unit 51 includes a secondary electron detector 53 for acquiring scanning electron microscope images (SEM images) of the sample 17, an electron optical system control unit 54, an SEM image processing unit 55, a high-voltage stabilization power supply 56, an input device 57, a display 58, and a storage device 59, and is configured to control these components. The output of the secondary electron detector 18 disposed in the analysis chamber 11 is input to the secondary electron detector 53.

[0102] (Electron excitation detaches from the overall control unit)

[0103] like Figure 6 As shown, the overall control unit 52 for controlling the acquisition of ESD images includes a two-dimensional multi-channel scaler 60, a pulse counting unit 61, a synchronization control unit 62, a signal rearrangement unit 63 for measuring signals to a two-dimensional plane, a microprocessor 72, etc.

[0104] The output of the ion detection unit 20, located in the analysis chamber 11, is input to the pulse counting unit 61 via the electron excitation-desorption ion detection unit 67. A scanning signal is input from the electron-optical system control unit 54 to the electron excitation-desorption overall control unit 52, and control is performed synchronously with the SEM image. Furthermore, the electron excitation-desorption overall control unit 52 is connected to the display 65 and the storage device 66.

[0105] The microprocessor 72 can also be a microcontroller or other microcomputer, personal computer, or field-programmable gate array (FPGA).

[0106] In the overall control unit 52 for the excitation separation, the scanning signal input from the electron optical system control unit 54 to the synchronization control unit 62 is output to the first deflection coil 16b of the electron source 16 via the synchronization control unit 62 as a vertical scanning signal 62a.

[0107] The horizontal scan signal 62b from the synchronization control unit 62 is output to the second deflection coil 16c of the electronic source 16. Information 62c related to the scan position is output from the synchronization control unit 62 to the microprocessor 72.

[0108] The hydrogen ion counting signal 61a output from the pulse counting unit 61 is output to the microprocessor 72 as the hydrogen ion counting signal at each scanning position. The hydrogen ion count at each sample position counted by the pulse counting unit 61 can be used to obtain the hydrogen ion distribution permeated by the sample 17 by acquiring ESD images at a predetermined shooting time and accumulating multiple counts.

[0109] The ESD image generated by the microprocessor 72 is output to the display 65 via an input / output interface (I / O) 72a, and to the storage device 66 via an input / output interface (I / O) 72b.

[0110] The operation of the electronic excitation departure whole control section 52 will be described. Figure 7 is a schematic diagram showing the relationship between the scanning of the electron source 16 and the two-dimensional measurement of the ESD image. The electron beam 16a generated by the electron source 16 is scanned in the vertical direction and the horizontal direction by the first deflection coil 16b and the second deflection coil 16c, and is irradiated two-dimensionally to the sample 17.

[0111] In the synchronization control section 62 shown in Figure 7 The vertical scanning signal generated in the synchronization control section 62 is a digital clock signal. The vertical scanning signal is converted to a sawtooth wave by a digital-to-analog converter (DAC) 62d, and is applied to the first deflection coil 16b of the electron source 16. Likewise, the clock signal of the horizontal scanning signal as a digital signal is converted to a sawtooth wave by a digital-to-analog converter (DAC) 62e, and is applied to the second deflection coil 16c of the electron source 16.

[0112] The shooting timing signal (called ST signal) of 1 pulse is controlled to start so that the vertical scanning signal (Vertical clock) generates a total of 2048 pulses.

[0113] During the pulse width of the vertical scanning signal of 1 pulse, the pixel signal in the horizontal direction (Horizontal clock) is output a total of 2048 pulses. Thereby, a two-dimensional scan of about 4.19 million pixels of 2048 rows x 2048 columns (= 4194304) is generated. That is, the signal counted by the pulse counting section 61 can be obtained as the count of hydrogen ions of the ion detector 23 at each scanning position by synchronizing a plurality of counters constituted by the ST signal, the vertical scanning clock signal, and the horizontal scanning clock signal.

[0114] The shooting timing signal can be changed depending on the kind or magnification, resolution of the electron microscope used. For example, 1024 pulses of the vertical scanning signal and 1024 pulses of the pixel signal in the horizontal direction, or 900 pulses of the vertical scanning signal and 1200 pulses of the pixel signal in the horizontal direction, or the like can be used.

[0115] (Method for acquiring ESD image)

[0116] Figure 8 is a flowchart of measuring a two-dimensional ESD image caused by scanning. As shown in the figure, the two-dimensional ESD image can be acquired by the following steps.

[0117] Step 1: The ions desorbed from the surface of the sample 17 are detected by the ion detector 23 of the ion detection section 20.

[0118] Step 2: The quantitative measurement of the ions detected by the ion detector 23 is measured by the pulse counting section 61.

[0119] Step 3: The ions of the two-dimensional measurement points of the sample 17 are counted by the synchronization control section 62 of the clock signals for vertical scanning and the clock signals for horizontal scanning shown in FIG. 6. Figure 7

[0120] Step 4: The ion counts of the two-dimensional measurement points of the sample 17 measured in Step 3 are stored in the memory of the storage device 66.

[0121] Step 5: The ion signals stored in the memory of the storage device 66 are rearranged into a two-dimensional image based on the clock signals for vertical scanning and the clock signals for horizontal scanning.

[0122] Step 6: The ESD image acquired in Step 5 is displayed on the display 65 and stored in the storage device 66 as image and numerical data.

[0123] The ESD image of the same region as the SEM image is acquired by the above steps.

[0124] The acquisition of the ESD image of the above steps 1-6 can be performed by software made in a program making environment dedicated to measurement device control. As such software, LabVIEW (registered trademark) manufactured by National Instruments, Inc. (http: / / www.ni.com / labview / ja / ) can be used. The ESD image of the above steps 1-6 can be acquired by the two-dimensional multi-channel scaler 60 executed by the program made by LabVIEW in the microprocessor 72.

[0125] (Measurement method of hydrogen ions)

[0126] ​In order to measure hydrogen ions of the permeation sample 17 using the above hydrogen permeation diffusion path observation device 10, in the gas supply step, stress is applied to the sample 17 mounted on the diaphragm type sample holder 12. In the image acquisition step, by scanning the electron beam 16a irradiated from the electron source 16, secondary electrons emitted from the sample are acquired as a scanning electron microscope image (referred to as a SEM image), and atoms such as hydrogen atoms diffused into the sample from the back surface and emitted to the surface are made into hydrogen ions by electron stimulated desorption (ESD) of the electron beam, and an ESD image of the hydrogen ions is acquired in synchronization with the scanning of the electron beam. In this image acquisition step, the position resolution of the ESD image is preferably set to 50 nm or less and compared with the SEM image. Here, before the acquisition of the SEM image, the surface of the sample 17 can be etched, and then the SEM image is observed. In addition, the grain boundaries are determined from the SEM image, and the determined grain boundaries are superimposed and displayed on the SEM image and the ESD image. By investigating the correspondence of the grains and the hydrogen ion distribution obtained from the ESD image, it is possible to obtain structural information of the hydrogen ion release position in the grains.

[0127] In order to apply stress to the sample surface by the present application, for example, various samples shown in FIGS. 9 to 18 and the like described later are used, and it is only necessary to apply a vacuum pressure of 0.1 Pa or less to the upper surface of the sample and to apply a differential pressure of the total of the hydrogen partial pressure and the rare gas partial pressure "P" MPa to the lower surface of the sample. As shown in FIGS. 9 to 18 and the like described later, the sample 17 is mounted on the sample mounting portion 12b of the diaphragm type sample holder 12 as a diaphragm that separates the analysis chamber 11 and the hydrogen pipe 14. Then, the following steps are performed simultaneously or sequentially: a hydrogen gas supply step of supplying hydrogen gas from the hydrogen gas supply portion 19 to the hydrogen pipe 14 while the analysis chamber 11 is evacuated to have a sufficient degree of vacuum; and a pressurized gas supply step of supplying a rare gas as a pressurized gas from the pressurized gas supply portion 24 to the hydrogen pipe 14. In this way, a differential pressure is generated between the surface side and the back surface side of the sample 17 by the total pressure of the hydrogen partial pressure and the rare gas partial pressure. The partial pressure of the rare gas can be independently selected within a range of 0% or more and less than 100%, and thus by appropriately selecting the partial pressure of the rare gas, it is possible to independently generate a desired stress such as a tensile stress or a compressive stress on the surface side and the back surface side of the sample 17 with respect to the amount of hydrogen gas present. Figure 2 and Figure 4 As shown in FIGS. 9 to 18 and the like described later, the sample 17 is mounted on the sample mounting portion 12b of the diaphragm type sample holder 12 as a diaphragm that separates the analysis chamber 11 and the hydrogen pipe 14. Then, the following steps are performed simultaneously or sequentially: a hydrogen gas supply step of supplying hydrogen gas from the hydrogen gas supply portion 19 to the hydrogen pipe 14 while the analysis chamber 11 is evacuated to have a sufficient degree of vacuum; and a pressurized gas supply step of supplying a rare gas as a pressurized gas from the pressurized gas supply portion 24 to the hydrogen pipe 14. In this way, a differential pressure is generated between the surface side and the back surface side of the sample 17 by the total pressure of the hydrogen partial pressure and the rare gas partial pressure. The partial pressure of the rare gas can be independently selected within a range of 0% or more and less than 100%, and thus by appropriately selecting the partial pressure of the rare gas, it is possible to independently generate a desired stress such as a tensile stress or a compressive stress on the surface side and the back surface side of the sample 17 with respect to the amount of hydrogen gas present.

[0128] Representative examples of the sample 17 suitable for measuring hydrogen ions by applying stress by a differential pressure (five kinds of 17A to 17E shown below) will be described.

[0129] (Sample 17A)

[0130] Figure 9A to Figure 9Cis a structural view showing one example of a test piece shape (test piece 17A) as a stress analysis object in the present application.

[0131] In the central portion of a disc-shaped metal plate having a plate thickness b = 1 mm, a hole (recess) having a diameter d = 10 mm and a depth of 0.9 mm was made in a concentric circular shape, and by leaving a thin plate portion t = 0.1 mm, a test piece 17A having a baffle portion 17b composed of the thin plate portion in the inner central portion of a circular ring portion 17a as a thick-walled peripheral portion was produced. In this test piece 17A, the baffle portion 17b becomes a pressure sensing region. When the inner edge of the circular ring portion 17a adjacent to the baffle portion 17b of the test piece 17A is fixed and a load of a pressure P is applied from one face, stress is generated in the baffle portion 17b.

[0132] Figure 10 is a plan view showing the stress distribution of the test piece 17A. The central region of the baffle portion 17b becomes a region in which tensile stress is generated on the surface. In contrast, the boundary region of the circular ring portion 17a and the baffle portion 17b becomes a region in which compressive stress is generated on the surface.

[0133] Figure 11A to Figure 11D is a graph showing the results of stress analysis of the cross section of the test piece shape of the test piece 17A using the finite element method (FEM). Figure 11A is the analysis results in a state where the differential pressure is 0.8 MPa, Figure 11B is the analysis results in a state where the differential pressure is 0.4 MPa, Figure 11C is the analysis results in a state where the differential pressure is 0.16 MPa, Figure 11D is the analysis results in a state where the differential pressure is 0.08 MPa. In the stress analysis results, the intensity of the tensile stress generated in each portion is indicated by the density of red color, and the intensity of the compressive stress is indicated by the density of blue color, but in Figure 11A to Figure 11D , the intensity of the tensile stress or the compressive stress is indicated by the density of black color.

[0134] Figure 11A (a) of FIG. 8 is a graph showing the analysis results from the cross-sectional end portion of the test piece 17A to the axis of symmetry (corresponding to the Figure 9B , Figure 9C , dotted line of FIG. 9D), (b) of FIG. 8 is a graph showing the analysis results of the baffle portion 17b in the vicinity of the axis of symmetry of the test piece 17A, and (c) of FIG. 8 is a graph showing the analysis results of the baffle portion 17b in the vicinity of the fixed end of the test piece 17A. Figure 11A Figure 11A Figure 11B to Figure 11D are also the same.

[0135] Figure 11A ​​​In (a) and (c), near the fixed end of the partition portion 17b, the surface side, which is the upper part, and the back side, which is the lower part, are shown more prominently relative to the paper surface. Specifically, the surface side is the area with strong compressive stress (corresponding to blue in the analysis screen), and the back side is the area with strong tensile stress (corresponding to red in the analysis screen). Figure 11B to Figure 11D The same applies. Therefore, it can be seen that in the boundary region adjacent to the fixed end of the partition portion 17b, even with a thickness of 0.1 mm, the bending stress (e.g., Figure 11D The pressure (approximately 214 MPa) is also concentrated in the middle.

[0136] On the other hand, focusing on Figure 11A In (b), the difference in intensity is not obvious on the gray scale, but in the central region near the axis of symmetry of the partition portion 17b, high tensile stress (equivalent to orange in the analysis screen) is observed in most of the area including the surface side, while slight compressive stress (equivalent to light blue in the analysis screen) is observed on the back side. This indicates that the compressive component on the back side of the partition portion 17b decreases as the differential pressure increases and the plastic deformation becomes larger.

[0137] In addition, comparison Figure 11A to Figure 11C (b) As the differential pressure decreases, the tensile stress on the surface side and the compressive stress on the back side gradually decrease. Figure 11D In (b), the tensile stress (equivalent to orange-yellow in the analysis screen) and compressive stress (equivalent to light blue in the analysis screen) are displayed on half of the surface side and half of the back side.

[0138] according to Figure 11A to Figure 11D The analysis results show that in the central region of the partition 17b, such as Figure 11D As shown, within a small differential pressure and elastic deformation range, the tensile stress on the surface side and the compressive stress on the back side are generated symmetrically, such as... Figure 11A As shown, when the differential pressure increases and the plastic deformation increases, the width and size of the compressive component region on the back side decreases relative to the width and size of the tensile stress region on the surface side.

[0139] Therefore, by appropriately setting the differential pressure between the surface side and the back side of the sample 17A, the desired tensile stress and compressive stress can be generated in each part. When observing hydrogen permeation, the partial pressure of hydrogen is fixed, and the pressure of the pressurized gas is changed from the pressurized gas supply unit 24. Thus, the magnitude of the stress applied to the test sample can be controlled according to the magnitude of its total pressure P.

[0140] (Sample 17B)

[0141] Figure 12A to Figure 12C This is a structural diagram illustrating another example (sample 17B) of the shape of the object specimen for stress analysis according to the present invention. Figure 12A It is a top view. Figure 12B It is a sectional view.Figure 12C is a structural perspective view. In the central portion of a disc-shaped metal plate having a plate thickness b = 0.5 mm, a hole (recess) having a diameter d = 10 mm and a depth of 0.4 mm was formed in a concentric circular shape, and a thin plate portion t = 0.1 mm was left to produce a specimen 17B having a partition portion 17b as a thin plate portion in the inner central portion of the thick-walled circular ring portion 17a.

[0142] Figure 13A to Figure 13C is an explanatory view Figure 12A to Figure 12C is a graph of the stress analysis results based on the finite element method (FEM) for the specimen 17B when P is 0.2 MPa, Figure 13A shows the boundary conditions of the finite element method analysis based on a two-dimensional axisymmetric model, Figure 13B shows the radial stress distribution on the upper and lower surfaces of the specimen sheet obtained by analysis, Figure 13C shows a deformation map of a deformation ratio of 20 times obtained by analysis. It can be confirmed that a deformation protruding upward is generated in the central portion of the partition portion 17b, and a tensile stress of about 220 MPa is applied to the upper surface of the region 17d (solid line of Figure 13B On the other hand, a compressive stress of 100 MPa is applied to the lower surface of the region 17d (dotted line of Figure 13B In addition, a compressive stress of about 250 MPa is applied to the upper surface of the region 17c near the boundary between the partition portion 17b and the circular ring portion 17a, and a tensile stress of 350 MPa is applied to the lower surface of the region 17c. In this way, when a pressure is applied from the lower side of the specimen shape of Fig. 12, opposite direction stresses are generated on the upper and lower surfaces in the regions 17d and 17c of the specimen 17.

[0143] (Specimen 17C)

[0144] Figure 14A to Figure 14C is a structural view showing another example of a structure in which only a tensile stress is applied to the upper and lower surfaces of the central portion of a specimen (specimen 17C), Figure 14A is a plan view, Figure 14B is a sectional view, Figure 14C is a structural perspective view.

[0145] In the central portion of a disc-shaped metal plate having a plate thickness b = 0.5 mm, a hole (recess) having a diameter d = 1.6 mm and a depth of 0.4 mm was formed in a concentric circular shape, and a thin plate portion t = 0.1 mm was left to produce a specimen 17C having a partition portion 17b as a thin plate portion in the inner central portion of the thick-walled circular ring portion 17a. In this specimen 17C, the diameter of the partition portion 17b is reduced compared to the specimen 17B shown in Figure 12A to Figure 12C

[0146] Figure 15A to Figure 15C is an explanatory view in Figure 14A to Figure 14C ​Fig. 17C is a graph showing the stress analysis results based on the finite element method (FEM) when P is 0.2 MPa, Figure 15A Fig. 17C is a graph showing the stress analysis results based on the finite element method (FEM) when P is 0.2 MPa, Figure 15B Fig. 17C is a graph showing the stress analysis results based on the finite element method (FEM) when P is 0.2 MPa, Figure 15C Fig. 17C is a graph showing the stress analysis results based on the finite element method (FEM) when P is 0.2 MPa,

[0147] (Sample 17D)

[0148] As the sample 17D, except that the diameter of the hole (recess) formed in the central portion of the disc-shaped metal plate is as small as 0.4 mm, all other parts are the same as the sample 17C shown in Fig. 17C, and the structure having the partition portion 17b as a thin plate portion is provided in the inner central portion of the thick-walled annular portion 17a. Figure 14A to Figure 14C

[0149] Figure 16A Fig. 17C is a graph showing the stress analysis results based on the finite element method (FEM) when P is 0.2 MPa, Figure 16B Fig. 17C is a graph showing the stress analysis results based on the finite element method (FEM) when P is 0.2 MPa, Figure 16A Fig. 17C is a graph showing the stress analysis results based on the finite element method (FEM) when P is 0.2 MPa, Figure 16B Fig. 17C is a graph showing the stress analysis results based on the finite element method (FEM) when P is 0.2 MPa,

[0150] (Sample 17E)

[0151] Figure 17A to Figure 17C Fig. 17C is a graph showing the stress analysis results based on the finite element method (FEM) when P is 0.2 MPa, Figure 17A Fig. 17C is a graph showing the stress analysis results based on the finite element method (FEM) when P is 0.2 MPa, Figure 17B Fig. 17C is a graph showing the stress analysis results based on the finite element method (FEM) when P is 0.2 MPa, Figure 17C Fig. 17C is a graph showing the stress analysis results based on the finite element method (FEM) when P is 0.2 MPa,

[0152] In the central portion of the disc-shaped metal plate having a plate thickness b = 0.5 mm, a hole (recess) having a diameter d = 1.6 mm and a depth of 0.4 mm from the upper surface of the sample is made in a concentric circular shape, and by leaving a thin plate portion t = 0.1 mm, the sample 17E having the partition portion 17b as a thin plate portion is provided in the inner central portion of the thick-walled annular portion 17a.

[0153] Figure 18A to Figure 18C Fig. 17C is a graph showing the stress analysis results based on the finite element method (FEM) when P is 0.2 MPa,​Figure 17A to Figure 17C a graph of stress analysis results based on the finite element method (FEM) for the specimen 17E when P is 0.2 MPa, Figure 18A shows boundary conditions for finite element method analysis based on a two-dimensional axisymmetric model, Figure 18B shows radial stress distribution on the upper and lower surfaces of the specimen sheet obtained by analysis, Figure 18C shows a deformation map at a deformation magnification of 100 times obtained by analysis. In the separator portion 17b of the specimen 17E, the stress magnitude is different between the upper and lower surfaces of the specimen, and compressive stress is applied to both the upper and lower surfaces of the specimen.

[0154] As the specimen 17 suitable for applying stress by differential pressure, it is not limited to the above-described representative specimen examples 17A to 17E, and can be appropriately changed. In the above description, as the thick-walled peripheral portion, the annular portion 17a having a circular ring shape is exemplified, but the peripheral portion can have various ring shapes such as a polygonal shape, a special shape, and a shape in which the peripheral portion is not continuous in a ring shape such as a semicircular shape, a U shape, and the like. By providing the peripheral portion in a shape different from the annular portion 17a, the stress concentration state is made different from the circular ring shape, and thus it is possible to obtain an insight different from the circular ring shape according to each shape. In the specimens 17A to 17D, the circular separator portion 17b is disposed at the outermost surface on the side of the analysis chamber 11, and although in the specimen 17E, the circular separator portion 17b is disposed at the outermost surface on the side of the hydrogen pipe 14, the separator portion 17b can be another shape such as a polygonal shape, and it is possible to generate a desired stress by appropriately selecting the size of the separator portion 17b and the position in the thickness direction of the peripheral portion.

[0155] (Second Embodiment)

[0156] Next, the point defect position detection device of the present application and the point defect position detection method using the same will be described. The point defect position detection device shares main parts with the aforementioned hydrogen permeation diffusion path observation device. In addition, the point defect position detection method shares main parts with the aforementioned method of measuring the observation object ions of the permeation specimen.

[0157] Figure 19 is a functional block diagram of the control section 50A in the point defect position detection device of the present application, and the same parts as those in the aforementioned Figure 5 function in the same manner as in the aforementioned

[0158] As Figure 19As shown, the control section 50A is configured to include an electron microscope overall control section 51 that controls the scanning electron microscope 15, and an electron stimulated desorption overall control section 52 that controls acquisition of the ESD image. In this embodiment, a point defect position extraction section 68 for extracting the position of the point defect is provided. In the point defect position extraction section 68, by comparing and analyzing the SEM image saved in the storage device 59 by the electron microscope overall control section 51 and the ESD image saved in the storage device 66 by the electron stimulated desorption overall control section 52 at 50 nm or less, point defect position detection can be performed. That is, the position resolution of the hydrogen release position, that is, the point defect, essentially depends on the magnification of the scanning electron microscope 15, so the position resolution of the ESD image can be improved to be equal to the magnification of the scanning electron microscope 15, for example, to obtain a position resolution of 50 nm or less. Thus, by comparing the SEM image of the sample 17 saved in the storage device 59 and the ESD image of the sample 17 saved in the storage device 66 at the same position resolution, the point defect on the sample surface side can be acquired from the SEM image and the structural information related to the release position of the observation object ion can be acquired from the ESD image. Further, as described later, from the structural information related to the release position of the observation object ion acquired from the ESD image and the point defect acquired with the SEM image, the point defect position of the sample can be determined. In this embodiment, as in the first embodiment, a stress effect extraction section 69 for extracting the effect when stress is applied to the sample by the differential pressure is provided. In the stress effect extraction section 69, by analyzing the image saved in the storage device 66, the effect of the stress can be used for point defect detection.

[0159] The operation of the point defect position detection device thus configured will be described. The detection of the point defect can be performed by the following steps.

[0160] Step 11: A sample having a point defect is prepared. As a sample having a point defect, a sample having a surface whose surface structure is modified, a sample having a surface on which a barrier film is coated, a sample having a surface on which a multilayer film is formed, and the like can be given.

[0161] Step 12: The sample having a point defect prepared in step 11 is disposed in the temperature-variable diaphragm-type sample holder 12. The sample can be disposed on the sample mounting portion 12b by the sample fixing plate 13. By simultaneously or sequentially performing the observation object gas supply process of supplying the observation object gas to the back surface side of the sample mounted in the diaphragm-type sample holder 12 and the pressurized gas supply process of supplying the pressurized gas, as in the first embodiment, the sample is caused to generate a desired stress and the observation object gas is supplied.

[0162] Step 13: As an image acquisition process, first, the SEM image of the sample is acquired.

[0163] Step 14: Analysis of the sample surface is performed as necessary. In the analysis of the sample surface, an Auger electron spectrometer can be used.

[0164] Step 15: A gas is introduced from the back surface of the sample as necessary, and mass analysis is performed by the mass analyzer 35.

[0165] Step 16: Subsequently, as an image acquisition process, an ESD image of the sample is acquired. The ESD image can be acquired by the same steps 1-6 as in the first embodiment.

[0166] Step 17: Comparison of the SEM image and the ESD image of the sample is performed. At this time, the position resolution can be set to 50 nm or less. Thus, the point defect of the sample can be determined.

[0167] The production of the sample with a point defect in Step 11 will be described. The sample with a point defect is produced in order to confirm the effect of the point defect position detection method, and in the actual sample investigation, the point defect does not need to be intentionally provided.

[0168] First, in the case where the surface modification layer is formed by changing the surface structure of the sample substrate, a method of performing chemical etching or physical excitation on the sample can be given. In the case where the sample substrate is reacted to produce another substance, for example, a surface oxidation layer or a surface nitridation layer can be formed by changing the surface structure of the front surface and / or the back surface of the sample by oxidation or nitridation. Further, a surface modification layer of a film formed of a substance different from the sample can be formed on the sample substrate.

[0169] The purpose of the surface modification can be roughly classified into two. One of the purposes is not to adsorb gas molecules from a gas atmosphere in contact with the modified surface layer. As the other purpose, a gas molecule source (for example, hydrogen atoms and the like) is not to permeate from the substrate inside the modified surface layer.

[0170] Therefore, in the case where the surface modification layer of the sample is formed of a material that does not permeate a gas molecule or an atom such as a hydrogen atom or the like for the purpose of shielding, the portion where the surface modification layer is not formed becomes a point defect, and a gas molecule source such as a hydrogen atom or the like permeates from the substrate inside the surface modification layer to the analysis chamber via the point defect of the surface modification layer, and thus the ESD image is acquired.

[0171] Second, in the case where the surface modification layer is formed by various deposition methods, the portion where the surface modification layer is not formed becomes a point defect. As a barrier film, for example, a metal film and a polymer film for hydrogen diffusion barrier, water vapor diffusion barrier, helium permeation barrier, and the like can be given. Further, as a barrier film, a surface modified by a dense ceramic film or an oxide film or the like for the purpose of hindering the adsorption of oxygen, nitrogen, carbon-based gas molecules can be given.

[0172] The present application is not limited to the above-described embodiments, and various modifications can be made within the scope of the application described in the claims, and of course these are included in the scope of the present application. For example, the shape of the test piece 17 is not limited to a circular shape. A quadrangular or polygonal plate can be used as the test piece.

[0173] (third embodiment)

[0174] Examples of measuring the behavior of various gas diffusion, permeation using the observation object gas permeation diffusion path observation device using the same main part as the first embodiment will be described. Figure 20 and Figure 21 A functional flowchart of the observation object permeation diffusion path observation device of the present application is shown. Sequentially programmed repeated measurements of the observation object gas partial pressure, pressurized gas pressure, and time series according to the measurement purpose, whereby the behavior of various gas diffusion, permeation can be measured.

[0175] Figure 20 is a flowchart for extracting the stress application effect from the measurement of the present application.

[0176] After the test piece is processed into a shape in which stress can be applied, it is installed in the diaphragm type test piece holder 12 and set in the scanning electron microscope 15, the observation object gas and the pressurized gas of pressure 1 are introduced, the SEM image is acquired, and the ESD image as the permeation image of the observation object gas is acquired, and each image is saved. Next, in a state in which the gas pressure of the observation object gas is fixed, after the gas pressure of the pressurized gas is changed to become the gas pressure 2, the SEM image is acquired, and the ESD image as the permeation image of the observation object gas is acquired, and each image is saved. Similarly, while changing the pressurized gas to the gas pressure 3, 4, 5,..., n, the SEM image and the ESD image of the observation object gas are sequentially acquired, and each image is repeatedly saved. Then, by classifying these ESD images with the pressurized gas as a variable, the permeation characteristics of the observation object gas in the stress field can be extracted.

[0177] Figure 21This is a flowchart for extracting the pressure dependence of the strain field from the measurements of this invention. After the sample is processed into a shape capable of applying stress, it is mounted on a diaphragm-type sample holder 12 and placed inside a scanning electron microscope 15. The target gas and the pressurized gas used to apply stress (pressure 1) are introduced, and SEM images are acquired. ESD images, which serve as permeation images of the target gas, are also acquired and saved. Next, after changing the pressure of the target gas to pressure 2, SEM images are acquired, and ESD images are acquired and saved. When the pressure of the target gas is a non-negligible proportion (1% or more) compared to the pressure of the stress-applying gas, the pressure of the stress-applying gas is reduced to a pressure that balances the pressurization of the target gas in order to eliminate variations in the sum of the pressures of the target gas and the stress-applying gas. The pressure of the target gas is repeatedly measured at pressures 3, 4, 5, ..., n and saved. By classifying these ESD images with the target gas pressure as a variable, the pressure dependence of the permeation characteristics of the target gas in the stress field can be extracted.

[0178] In the aforementioned gas supply process for the target gas and pressurized gas, the differential pressure can be changed by altering the pressure of the pressurized gas or the partial pressure of the target gas, or both. That is, the differential pressure can be changed by altering the pressure of the target gas and / or the pressurized gas. Furthermore, the image acquisition process is repeated each time the differential pressure is changed, and by acquiring SEM and ESD images, the escape behavior of the target gas relative to the differential pressure change can be measured.

[0179] By applying stress to the surface film of a sample processed into a shape capable of applying stress... Figure 20 The same measurement shown can investigate the generation of point defects in the stress field, and can also extract the sample stress characteristics relative to the observed gas released from point defects in the surface film. Furthermore, by changing the temperature of sample 17, the measurement can be performed, and the hydrogen ion release data can be calculated, along with the hydrogen diffusion rate and / or diffusion coefficient within sample 17, time, and two-dimensional position information of sample 17.

[0180] Industrial application

[0181] The permeation and diffusion path observation device for the target gas according to the present invention can apply stress to a sample measured using an in-situ hydrogen microscope, and is therefore preferably used for the selection of structural materials for hydrogen storage facilities, nuclear reactor containment vessels, medical facilities using high-energy rays such as neutron rays and electron beams, research facilities, etc.

[0182] The measurement method of the observation target gas according to the present application can explore the mechanism of the deterioration phenomenon such as the embrittlement phenomenon of the structural material caused by the hydrogen-containing observation target gas, and is suitable for providing design guidance for non-destructive inspection, hydrogen storage facilities, nuclear reactor containment vessels, medical facilities using high-energy rays such as neutron rays and electron beams, and research facilities.

[0183] The point defect position detection device and the point defect position detection method using the same according to the present application can detect, for example, a gas absorbed in a sample, a gas permeated from a point defect in a sample, and are effective in providing design guidance for non-destructive inspection, hydrogen storage facilities, nuclear reactor containment vessels, medical facilities using high-energy rays such as neutron rays and electron beams, and research facilities.

[0184] Symbol explanation

[0185] 10: hydrogen permeation diffusion path observation device; 11: analysis chamber; 11a: lead wire leading-out port; 12: diaphragm-type sample holder; 12a: diaphragm-type sample holder single tube sample side; 12b: diaphragm-type sample holder single tube flange side; 13: sample fixing plate; 14: hydrogen piping (observation object gas piping); 15: scanning electron microscope; 16: electron source; 16a: electron beam; 16b: first deflection coil; 16c: second deflection coil; 17, 17A, 17B, 17C, 17D, 17E: sample; 17a: circular ring portion (peripheral portion); 17b: partition portion; 18: secondary electron detector; 19: hydrogen gas supply portion (observation object gas supply portion); 20: hydrogen ion detection portion (observation object ion supply portion); 21: collection mechanism; 21a: mounting portion; 21b: mesh portion; 21c: mesh holding portion; 22: ion energy resolution portion; 23: ion detector; 24: pressurized gas supply portion (rare gas supply portion); 31: sample stage portion; 32: sample heating portion; 33: sample temperature measurement portion; 34: sample position adjustment portion; 35: mass analyzer; 36: Auger electron spectroscopic analyzer; 37: first vacuum exhaust portion; 38: second vacuum exhaust portion; 41: hydrogen ion (observation object ion); 50, 50A: control portion; 51: electron microscope overall control portion; 52: electron excitation detachment overall control portion; 53: secondary electron detection portion; 54: electron optical system control portion; 55: SEM image processing portion; 56: high voltage stabilization power supply; 57: input device; 58: display; 59: storage device; 60: two-dimensional multi-channel scaler; 61: pulse counting portion; 61a: count signal of hydrogen ion; 62: synchronization control portion; 62a: vertical scanning signal; 62b: horizontal scanning signal; 62c: information related to scanning position; 62d, 62e: digital-to-analog converter; 63: measurement signal two-dimensional plane rearrangement portion; 64: ESD image processing portion; 65: display; 66: storage device; 67: electron excitation detachment ion detection portion; 68: point defect position extraction portion; 69: stress effect extraction portion; 72: microprocessor; 72a, 72b: input / output interface; W: opening window (mounting region).

Claims

1. An observation apparatus for observing a permeation diffusion path of a target gas, comprising: a scanning electron microscope having an analysis chamber that accommodates a sample, an electron source that irradiates an electron beam to the sample, and a secondary electron detector that detects secondary electrons generated by the electron beam irradiated to the sample; a target ion detector that detects target ions generated by the electron beam irradiated to the sample from the electron source; a target gas supply section that supplies a target gas to a target gas pipe connected to a back surface side of the sample; a pressurized gas supply section that is connected to the target gas pipe and supplies a pressurized gas; a diaphragm-type sample holder that mounts the sample as a diaphragm that separates the analysis chamber and the target gas pipe; and a control section, the control section acquires a SEM image of the secondary electrons generated from the sample by scanning of the electron beam, the control section simultaneously or sequentially performs target gas supply of supplying a partial pressure of the target gas from the target gas supply section and pressurized gas supply of supplying a partial pressure of the pressurized gas from the pressurized gas supply section, a differential pressure that generates stress in the sample is generated by a total pressure of the partial pressure of the target gas and the partial pressure of the pressurized gas generated between the analysis chamber and the target gas pipe, the target gas that diffuses into the sample from the back surface of the sample and escapes to a surface of the sample becomes the target ions by electron excitation detachment by the electron beam, and an ESD image of the target ions detected by the target ion detector is acquired in synchronization with scanning of the electron beam.

2. The observation apparatus for observing a permeation diffusion path of a target gas according to claim 1, wherein the partial pressure of the pressurized gas is independently selected with respect to the target gas.

3. The observation apparatus for observing a permeation diffusion path of a target gas according to claim 1 or 2, wherein the target ion detector includes: a collection mechanism that collects the target ions generated from the surface of the sample; an ion energy resolution section that is provided at an upper portion of the collection mechanism, that incident the target ions collected by the collection mechanism, and that removes substances other than the target ions; and an ion detector that detects the target ions that pass through the ion energy resolution section and that outputs to the control section, the collection mechanism has a mesh or a lens fixed to a periphery of the sample, and is configured to collect the target ions and to incident to the ion detector by applying a predetermined voltage between the mesh or the lens and a ground.

4. The observation apparatus for observing a permeation diffusion path of a target gas according to claim 1 or 2, wherein the diaphragm-type sample holder includes a sample mounting section having an open window, and the sample is mounted to the sample mounting section in a state of plugging the open window.

5. The observation apparatus for observing a permeation diffusion path of a target gas according to claim 4, wherein the sample is fixed to the diaphragm-type sample holder. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 6. The permeation diffusion path observation apparatus for an observation target gas according to claim 1 or 2, wherein the observation target gas is any one of molecules, atoms and ions from any one of hydrogen, deuterium, helium, oxygen, nitrogen, water, or a gas related to a purpose of use of a sample at the time of production of the sample, any one of molecules, atoms and ions from a plurality of gases among them.

7. The permeation diffusion path observation apparatus for an observation target gas according to claim 1 or 2, wherein the pressurized gas is a pressurized gas of at least one selected from the group consisting of helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), radon (Rn) and nitrogen (N).

8. An observation sample installed in the permeation diffusion path observation apparatus according to any one of claims 1 to 7, the observation sample comprising: a thin-walled partition portion stressed by a differential pressure at the time of observation; and a thick-walled peripheral portion formed around the partition portion, the observation sample being installed as a diaphragm that separates between the analysis chamber and the observation target gas pipe in the diaphragm-type sample holder.

9. The observation sample according to claim 8, wherein the sample is a metal flat plate, a plate material that thins a welded portion of a metal, a plate material that thins a metal having a corrosion site, a ceramic plate, a polymer plate, or a plate material composed of a composite material thereof.

10. The observation sample according to claim 8 or 9, wherein the partition portion is formed in a circular shape or a polygonal shape, and the size and thickness of the partition portion, and the position of the partition portion in the thickness direction of the peripheral portion are set so that, by the differential pressure at the time of observation, a tensile stress or a compressive stress is generated on a surface on the analysis chamber side and a surface on the observation target gas pipe side.

11. A measurement method of an observation target gas that permeates a sample, the measurement method being a method of measuring the observation target gas using the permeation diffusion path observation apparatus according to any one of claims 1 to 7, the measurement method comprising: a gas supply step of simultaneously or sequentially performing observation target gas supply of supplying a partial pressure of the observation target gas from the observation target gas supply portion, and pressurized gas supply of supplying a partial pressure of the pressurized gas from the pressurized gas supply portion, and stressing the sample by a differential pressure generated by a total pressure of the partial pressure of the observation target gas and the partial pressure of the pressurized gas generated between the analysis chamber and the observation target gas pipe; and an image acquisition step of acquiring a SEM image using secondary electrons generated from the sample by scanning of the electron beam, and acquiring an ESD image detected by the ion detection portion in synchronization with the scanning of the electron beam by ionization of the observation target gas diffused into the sample from the back surface of the sample and escaped to the sample surface by electron excitation of the electron beam. In the image acquisition step, the positional resolution of the SEM image and the ESD image is set to 50 nm or less, and the structure information relating to the release position of the observation object ion is acquired.

12. The measurement method of the observation object gas according to claim 11, wherein, In the gas supply step, the differential pressure is generated by changing the partial pressure of the pressurized gas or the partial pressure of the observation object gas or both, the differential pressure is sequentially changed, and the image acquisition step is repeatedly performed, and the escape behavior of the observation object gas with respect to the differential pressure change is measured from the SEM image and the ESD image acquired each time.

13. A point defect position detection method for detecting a point defect position using the measurement method of the observation object gas according to claim 12.

14. A point defect position detection device comprising: the permeation diffusion path observation device of the observation object gas according to any one of claims 1 to 7; and a point defect position extraction section that detects a point defect position of the sample from the SEM image and the ESD image of the sample.

15. A point defect position detection method for detecting an atom or a molecule leaked from the inside or the back surface of a sample through a point defect as an ion using the point defect position detection device according to claim 14, the point defect position detection method for determining a point defect position of a sample, comprising the steps of: preparing a sample; arranging the sample on the diaphragm type sample holder; acquiring the SEM image of the sample; acquiring the ESD image of the sample; and determining a point defect position of the sample by comparing the SEM image and the ESD image of the sample.

Images