Method of producing specimen and method of observing specimen

Abstract

To provide a method of producing a specimen, by which restrictions derived from equipment to be used are relaxed more than in the conventional technique in observation of the specimen.SOLUTION: A method of producing a specimen for observing an observation object, the method includes: an installation step of installing the observation object in a reaction chamber; a first treatment step of attaching a gaseous metal compound to an entire surface of the observation object to form a layer of a metal compound; and a second treatment step of reacting the metal compound with a gaseous oxidizing agent to form a layer of a metal oxide or a metal from the layer of the metal compound, where the observation object contains a reactive compound having reactivity with at least one target atmospheric component selected from components in the atmosphere excluding oxygen gas, and at least each of the steps from the installation step to the second treatment step is performed under an atmosphere not containing the target atmospheric component.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for producing a sample and a method for observing a sample. [Background technology]

[0002] In order to analyze the structure and composition of a minute material using an analytical device such as an electron microscope, the material may be pretreated. For example, Patent Document 1 describes a method for preparing a physical property analysis sample, in which a contrast enhancement layer is formed on the surface of a sample to be analyzed, the contrast enhancement layer including a plurality of first material layers and a plurality of second material layers stacked on top of each other, the first material layers and the second material layers being made of different materials. According to the technology described in Patent Document 1, the contrast in an image of the sample taken with an electron microscope is enhanced. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2022-107491 A Summary of the Invention [Problem to be solved by the invention]

[0004] Some materials that are used as objects of observation react with certain components in the atmosphere and denature or deform, making it impossible to observe the original properties of the material. When observing such materials using various methods, special equipment such as dedicated sample holders may be used to prevent the sample from being exposed to the atmosphere.

[0005] As an example, a sample holder for an electron microscope will be described. FIG. 3(a) is a schematic diagram of a general-purpose sample holder that has been conventionally used for introducing a sample into the observation chamber of an electron microscope. FIG. 3(b) is a schematic diagram of an air-tight sample holder that has been conventionally used for introducing a sample into the observation chamber of an electron microscope. As shown in FIGS. 3(a) and (b), the air-tight sample holder is larger and heavier than general-purpose ones, and is therefore less stable. Therefore, when an air-tight sample holder is used, the vibration and drift of the sample stage provided at the tip increases during observation, which reduces the observation accuracy and tends to make high-magnification photography difficult.

[0006] 3(c) and (d) are enlarged schematic diagrams of the tip of the air-blocking sample holder shown in FIG. 3(b), where (c) shows the sample stage retracted and (d) shows the sample stage exposed. After fixing a sample to the sample stage at the tip of the air-blocking sample holder, the air-blocking sample holder retracts the sample stage inside the shaft as shown in FIG. 3(c), thereby isolating the sample from the atmosphere. Then, when the tip of the air-blocking sample holder is introduced into the observation chamber of the electron microscope and decompression is completed, the air-blocking sample holder exposes the sample stage again as shown in FIG. 3(d). This retraction mechanism is a complex mechanism that is not found in the stage of a general-purpose sample holder, and due to its complexity, the movable range of the sample stage in the tilt direction is limited, and the degree of freedom of photography is low. For example, while the tilt angle range of a general-purpose sample holder is about ±30°, the tilt angle range of the air-blocking sample holder is limited to about ±5°. In addition, because the structure of the tip of the air-blocking sample holder is complex, it is difficult to bring the detector close to the sample stage, and as a result, the detection sensitivity tends to decrease.

[0007] As described above, in the observation of an object that reacts with some atmospheric components when exposed to the components, the prior art has the problem that the observation accuracy, the degree of freedom in photographing, and the detection sensitivity are limited due to the equipment used. Patent Document 1 does not disclose such a problem or a means for solving the problem.

[0008] One aspect of the present invention aims to provide a method for producing a sample for observing an object that reacts with a certain component contained in the atmosphere when exposed to the component, wherein the restrictions imposed by the equipment used in observing the sample are alleviated as compared to conventional techniques. [Means for solving the problem]

[0009] In order to solve the above problems, a sample manufacturing method according to one embodiment of the present invention is a sample manufacturing method for observing an object to be observed, which includes an installation step of installing the object to be observed in a reaction chamber, a first processing step of forming a layer of the metal compound by adhering a gaseous metal compound to the entire surface of the object to be observed, and a second processing step of forming a layer of metal oxide or metal from the layer of the metal compound by reacting the metal compound with a gaseous oxidizing agent, wherein the object to be observed contains a reactive compound that is reactive to at least one target atmospheric component selected from components in the atmosphere excluding oxygen gas, and at least each of the steps from the installation step to the second processing step is performed in an atmosphere that does not contain the target atmospheric component. Effect of the Invention

[0010] According to one aspect of the present invention, there is provided a method for producing a sample, which reduces limitations imposed by the equipment used in observing the sample as compared to the prior art. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a block diagram illustrating an outline of an atomic layer deposition (ALD) apparatus for performing a method for producing a sample according to one embodiment of the present invention. [Diagram 2] 1 is a graph showing EELS spectra of samples of Example 1 and Comparative Examples 1 and 2. [Diagram 3](a) is a schematic diagram of a conventionally used general-purpose specimen holder for introducing a specimen into the observation chamber of an electron microscope. (b) is a schematic diagram of a conventionally used air-tight specimen holder for introducing a specimen into the observation chamber of an electron microscope. (c) and (d) are enlarged schematic diagrams of the tip of the air-tight specimen holder shown in (b), where (c) shows the specimen stage in a retracted state and (d) shows the specimen stage in an exposed state. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] <Sample manufacturing method> A method for producing a sample according to one embodiment of the present invention is a method for producing a sample for observing an object to be observed, which includes a step of placing the object to be observed in a reaction chamber, a first processing step of forming a layer of the metal compound by attaching a gaseous metal compound to the entire surface of the object to be observed, and a second processing step of forming a layer of a metal oxide or metal from the layer of the metal compound by reacting the metal compound with a gaseous oxidizing agent, the object to be observed contains a reactive compound that has reactivity with at least one target atmospheric component selected from components in the atmosphere except oxygen gas, and at least each of the steps from the placing step to the second processing step is performed in an atmosphere that does not contain the target atmospheric component. The method for producing a sample according to one embodiment of the present invention will be described in detail below.

[0013] [Object of Observation] In this specification, the term "observation target" refers to an object to be observed. Also, the term "sample" refers to an object comprising an observation target and a metal oxide or metal layer formed on the entire surface of the observation target. In one aspect of the present invention, the observation target encapsulated in the metal oxide or metal layer can be observed, for example, for its structure and composition, by a predetermined observation method using the sample.

[0014] The object to be observed includes a reactive compound having reactivity with at least one target atmospheric component selected from components in the atmosphere, excluding oxygen gas. Examples of the target atmospheric component include water vapor, carbon dioxide, carbon monoxide, nitrogen dioxide, nitrous oxide, and hydrogen sulfide. In this specification, the reactivity with the target atmospheric component refers to a property of producing a compound different from both the object to be observed and the target atmospheric component by reacting with the target atmospheric component or catalyzing a reaction involving the target atmospheric component when exposed for 24 hours to an atmosphere at atmospheric pressure consisting of the target atmospheric component at the same concentration as that in the atmosphere and argon as the remainder. Here, the concentration in the atmosphere is, for example, 4% by volume for water vapor, 0.03% by volume for carbon dioxide, 0.01% by volume or less for carbon monoxide, 0.01% by volume or less for nitrogen dioxide, 0.01% by volume or less for nitrous oxide, and 0.01% by volume or less for hydrogen sulfide.

[0015] The reactive compounds include carbon dioxide absorbing compounds, deliquescent compounds, and hydrogenation catalytic compounds, such as lithium oxide (Li 2 O) and lithium sulfide (Li 2 S) and other lithium-containing materials; sodium oxide (Na 2 Examples of the reactive compound include sodium-containing substances such as lithium carbide (LiO), and catalytic precious metals such as platinum. Among them, the reactive compound is preferably at least one selected from the group consisting of lithium oxide and lithium sulfide. These reactive compounds are preferred because they have high reactivity with reactive compounds and therefore have a large benefit in that restrictions imposed by the equipment used are alleviated.

[0016] The content of the reactive compound in the observation object is not particularly limited, but is preferably 30% by mass or more, and more preferably 90% by mass or more. In the prior art, an observation object containing such a reactive compound content is easily denatured or deformed when exposed to the atmosphere, but according to one aspect of the present invention, denaturation or deformation is suitably prevented, making it possible to observe the original composition and structure of the observation object. The content of the reactive compound in the observation object does not have a particular upper limit, and may be 100% by mass or less.

[0017] The observation target may further contain other components in addition to the reactive compound, such as, but not limited to, inorganic oxides, resins, solvents, binders, and protective films formed to protect the sample.

[0018] Specific examples of the object of observation include a battery material for an all-solid-state battery containing lithium oxide as a positive electrode active material and PVDF (polyvinylidene fluoride) as a binder, a catalyst particle material in which platinum is supported on porous particles made of an inorganic oxide, and a catalyst particle material in which platinum is supported on a carbon material, and a battery material containing lithium sulfide. In the exemplified embodiments, the reactive compound may be an active substance that exerts a function desired for the material, and the other components may be a carrier that supports the active substance.

[0019] [Atomic Layer Deposition (ALD) Equipment] A sample manufacturing method according to an embodiment of the present invention may be a method for manufacturing a sample from an object to be observed by atomic layer deposition (ALD). First, an embodiment of an ALD apparatus for carrying out the sample manufacturing method will be described with reference to Fig. 1. Fig. 1 is a block diagram for explaining an outline of an ALD apparatus 10 for carrying out the sample manufacturing method according to an embodiment of the present invention.

[0020] As shown in FIG. 1, an ALD apparatus 10 includes an observation object introduction chamber 11, a reaction chamber 12, a pressure reduction section 13, a purge gas supply section 14, a precursor gas supply section 15, and an oxidizer gas supply section 16.

[0021] The observation object introduction chamber 11 is a chamber for introducing an observation object into the reaction chamber 12, and may be, for example, a glove box. The observation object introduction chamber 11 is separately connected to each of the reaction chamber 12 and the purge gas supply unit 14. The atmosphere inside the observation object introduction chamber 11 is purged by supplying purge gas from the purge gas supply unit 14.

[0022] The reaction chamber 12 is separately connected to each of the observation object introduction chamber 11, the pressure reducing section 13, the purge gas supply section 14, the precursor gas supply section 15, and the oxidizer gas supply section 16. The reaction chamber 12 also includes a heating section (not shown) such as an infrared heater, which can adjust the temperature inside the chamber. In the method for producing a sample according to one aspect of the present invention, a first processing step and a second processing step are mainly performed inside the reaction chamber 12, thereby forming a metal oxide or metal layer on the surface of the observation object.

[0023] The pressure reducing unit 13 includes a pump such as a turbo molecular pump and a rotary pump, etc. With this, the pressure reducing unit 13 adjusts the air pressure in the reaction chamber 12 and exhausts gases remaining in the reaction chamber 12, such as unreacted metal compound gas (i.e., gaseous metal compound), oxidant gas (i.e., gaseous oxidant), or purge gas, out of the reaction chamber 12.

[0024] The purge gas supply unit 14 supplies purge gas to each of the observation object introduction chamber 11 and the reaction chamber 12, and can control the flow rate of the purge gas. Types of purge gas include rare gases such as argon and helium, nitrogen, and dry air. The type of purge gas is selected according to the type of reactive compound contained in the observation object so that the reactive compound does not have reactivity with the purge gas. In other words, the purge gas is a gas that does not contain the target atmospheric component and is selected according to the type of reactive compound.

[0025] The precursor gas supply unit 15 includes a mass flow controller (MFC) for controlling the flow rate and temperature of the metal compound gas, which is the precursor gas, and thereby controls the metal compound gas supplied into the reaction chamber 12. The flow rate of the compound gas can be controlled.

[0026] Like the precursor gas supply unit 15, the oxidizing gas supply unit 16 includes a mass flow controller (MFC), which makes it possible to control the flow rate of the oxidizing gas supplied into the reaction chamber 12.

[0027] In addition, the ALD apparatus 10 preferably includes a control unit (not shown) for controlling each of the observation object introduction chamber 11, the reaction chamber 12, the pressure reduction unit 13, the purge gas supply unit 14, the precursor gas supply unit 15, and the oxidizer gas supply unit 16.

[0028] [Pretreatment process] Each step that may be included in the method for producing a sample according to one embodiment of the present invention will be described below. The method for producing a sample may include a pretreatment step of dispersing the object to be observed in a solvent or cutting the object to be observed into slices in an atmosphere that does not contain the target atmospheric component, prior to the installation step described below. By carrying out the pretreatment step, the object to be observed in the desired form can be obtained, and the subsequent steps can be carried out advantageously.

[0029] In one embodiment of the present invention, the pretreatment step is carried out in the observation object introduction chamber 11. Here, the observation object introduction chamber 11 is filled in advance with purge gas from the purge gas supply unit 14, and the atmosphere is purged. Therefore, the pretreatment step is carried out in an atmosphere that does not contain the target atmospheric components.

[0030] For example, when the object to be observed is obtained as an aggregate of primary particles, it is preferable to disintegrate the aggregates of particles of the object to be observed to some extent by carrying out a pretreatment step of dispersing the object to be observed in a solvent. Dispersing the particles of the object to be observed in a solvent has the effect of breaking up the aggregates.

[0031] The solvent used in the pretreatment step is not limited as long as it is a solvent in which the observation object can be dispersed, and known organic solvents such as alcohols such as ethanol and i-propanol, ketones such as acetone and methyl ethyl ketone, esters such as ethyl acetate, ethers such as dibutyl ether and 1,4-dioxane, aromatic solvents such as xylene, and hydrocarbon solvents such as hexane and cyclohexane can be used. The dispersion method for dissolving the aggregation of the observation object is not particularly limited, and for example, an ultrasonic dispersion device or the like may be used for dispersion. In the pretreatment step, it is preferable to remove the organic solvent used from the observation object by performing reduced pressure drying, heated drying, heated reduced pressure drying, or natural drying in the observation object introduction chamber 11 before performing the first treatment step.

[0032] Furthermore, for example, if the object to be observed is obtained as a bulk larger than the sample stage, it is preferable to carry out a pre-processing step of cutting the object to be observed into slices, thereby adjusting the size of the object to a size that can be placed on the sample stage.

[0033] The step of cutting out the observation object into slices can be carried out by a method known in the art. Examples of the method of cutting out the observation object into slices include cutting out by focused ion beam (FIB), cutting out by microtome method, polishing by electrolytic polishing method or chemical polishing method, and cutting out by Ar ion milling method. The method of cutting out the observation object into slices can be preferably the FIB method or the microtome method.

[0034] [Installation process] The method for producing a sample according to one embodiment of the present invention includes a setting step of setting an observation object in a reaction chamber 12. The setting step can be performed by introducing the observation object into the reaction chamber 12 through an observation object introduction chamber 11. Here, the observation object introduction chamber 11 and the reaction chamber 12 are filled in advance with a purge gas from a purge gas supply unit 14, and the atmosphere is purged. Therefore, the setting step is performed in an atmosphere that does not contain the target atmospheric component.

[0035] The object to be observed is placed in the reaction chamber 12 while being supported by a support. Here, the support is not particularly limited as long as it can support the object to be observed while substantially the entire surface of the object to be observed is exposed to the atmosphere, and examples thereof include a mesh or FIB grid made of glass, metal, or resin. When the object to be observed is liquid, the support is preferably a mesh, and when the object to be observed is cut out as a slice, the support is preferably a FIB grid. The FIB grid or mesh is more preferably a metal FIB grid or metal mesh made of gold, copper, nickel, molybdenum, SUS (stainless steel), or the like. In addition, the mesh and the FIB grid may have a coating formed on their surfaces.

[0036] A known method can be used to introduce the observation object into the reaction chamber 12 through the observation object introduction chamber 11. For example, when a glove box is used as the observation object introduction chamber 11, the observation object introduced into the glove box can be introduced into the reaction chamber 12 communicating with the glove box by an operator using gloves.

[0037] In one embodiment of the present invention, the object to be observed is introduced into the observation object introduction chamber 11 before the installation step or before the pretreatment step, if any, and here, it is preferable that the object to be observed is introduced into the observation object introduction chamber 11 in a sealed state and the seal is removed inside the observation object introduction chamber 11. This prevents the object to be observed from being exposed to the atmosphere before the installation step, which would cause the object to be denatured or deformed.

[0038] [First processing step] The method for producing a sample according to one embodiment of the present invention includes a first process step of forming a layer of a metal compound by attaching a gaseous metal compound to the entire surface of the object to be observed in a reaction chamber after the placing step. The first process step is a step of depositing a metal compound on the entire surface of the object to be observed, thereby covering the entire surface of the object to be observed with the metal compound. The first process step can be performed in a state where the support on which the object to be observed is placed is placed in the reaction chamber 12.

[0039] The metal compound used in the first treatment step is a precursor of a metal oxide, and is supplied in a vaporized state from the precursor gas supply unit 15 into the reaction chamber 12. The metal compound as the precursor may be any metal compound that can be vaporized (gasified) under a heating environment or a heating and reduced pressure environment, and that generates a metal oxide by reacting with an oxidizing agent. Examples of the metal compound include metal compounds containing metals such as hafnium (Hf), zirconium (Zr), aluminum (Al), silicon (Si), and titanium (Ti), and the metal has a functional group selected from the group consisting of an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 11 carbon atoms, a halogen such as chlorine and bromine, and hydrogen.

[0040] Specific examples of metal compounds include: hafnium compounds such as tetrakishafnium; aluminum compounds such as diethylaluminum ethoxide, tris(ethylmethylamido)aluminum, aluminum sec-butoxide, aluminum tribromide, aluminum trichloride, triethylaluminum, triisobutylaluminum, trimethylaluminum (TMA), and tris(diethylamido)aluminum; tetramethoxysilane and SiH 4 and titanium compounds such as tetraethoxytitanium. Among them, trimethylaluminum (TMA) is a more preferred metal compound because it can be suitably gasified and rapidly reacted with an oxidizing agent in the reaction chamber 12. These metal compounds are supplied into the reaction chamber 12 together with an inert gas, such as nitrogen, that does not contain the target atmospheric component. Therefore, the first treatment step is carried out in an atmosphere that does not contain the target atmospheric component.

[0041] Depending on the type and manufacturing conditions, the above-mentioned metal compound may form a metal, not a metal oxide, in the second treatment step. Therefore, the "metal oxide layer" described below can be interpreted as a "metal layer", but for convenience, the present invention will be described using only the "metal oxide layer" unless otherwise specified.

[0042] In the first processing step, when a metal compound gas, which is a precursor gas, is supplied to the reaction chamber 12, the metal compound is partially oxidized and deposited on the entire surface of the object to be observed. The by-products generated at this time vary depending on the type of metal compound, but may be, for example, alkanes such as methane and ethane, alcohols such as ethanol, halogens, hydrogen gas, etc.

[0043] The supply amount of the metal compound gas in one first processing step may be adjusted appropriately depending on the type of the object to be observed and the amount of the object to be observed to be subjected to the manufacturing method, but a flow rate within the range of 0.5 to 1 SCCM is preferable, which allows the metal compound to be supplied into the reaction chamber 12 in an amount sufficient to sufficiently consume the hydroxyl groups present on the surface of the object to be observed by reaction. Also, it is preferable to perform one first processing step for 1 to 5 seconds, which allows the metal compound to be sufficiently supplied to the surface of the object to be observed.

[0044] [First purge step] The method for producing a sample according to one embodiment of the present invention preferably includes a first purge step of purging unreacted metal compound gas from inside the reaction chamber 12 after the first process step and before the second process step. The first purge step can be performed by supplying a purge gas from the purge gas supply unit 14 to the reaction chamber 12 and purging the purge gas from the pressure reduction unit 13. This makes it possible to discharge the unreacted metal compound gas supplied into the reaction chamber 12 in the first process step and by-products generated by the reaction outside the reaction chamber 12. This makes it possible to suitably prevent the oxide gas supplied by the subsequent second process step from reacting with the unreacted metal compound gas remaining in the reaction chamber 12 and depositing on the surface of the observation object.

[0045] The supply amount of the purge gas in one first purge step is preferably within a flow rate range of 90 to 100 SCCM, and the first purge step is preferably performed for 5 to 50 seconds.

[0046] [Second processing step] The method for producing a sample according to one embodiment of the present invention includes a second process step, which is performed after the first process step or after the first purge step, in which a metal compound layer is reacted with a gaseous oxidizing agent to form a metal oxide layer from the metal compound layer. The second process step is performed by supplying an oxidizing gas from the oxidizing gas supply unit 16 into the reaction chamber 12 and reacting the metal compound chemically bonded to the surface of the observation object with the oxidizing gas. This forms a metal oxide layer on the surface of the observation object.

[0047] The oxidizing gas supplied into the reaction chamber 12 in the second treatment step is not particularly limited as long as it oxidizes the metal compound used in the first treatment step, but is preferably ozone or oxygen plasma from the viewpoint of high oxidizing power and excellent safety. Note that these oxidizing gases are supplied into the reaction chamber 12 together with an inert gas such as nitrogen that does not contain the target atmospheric components. Therefore, the second treatment step is carried out in an atmosphere that does not contain the target atmospheric components.

[0048] The amount of oxidant gas supplied in one second treatment step may be adjusted as appropriate depending on the type of object to be observed and the amount of object to be observed, but a flow rate within the range of 0.5 to 1 SCCM is preferable, which allows the metal compound to be supplied into the reaction chamber 12 in an amount sufficient to sufficiently consume the hydroxyl groups present on the surface of the object to be observed through a reaction. Also, it is preferable to perform one second treatment step for 1 to 5 seconds, which allows the oxidant gas to be sufficiently supplied to the surface of the object to be observed.

[0049] In the second processing step, when an oxidizing gas is supplied to the reaction chamber 12, the metal compound deposited on the surface of the observation object reacts with the oxidizing gas. As a result, the functional groups of the metal compound are replaced with OH groups, and a metal oxide layer is formed. At this time, by-products similar to those generated in the first processing step are generated.

[0050] [Second purge step] The method for producing a sample according to one embodiment of the present invention preferably includes, after the second treatment step, a second purge step of purging unreacted oxidant gas and by-products from inside the reaction chamber 12. The second purge step can be performed in the same manner as the above-mentioned first purge step, and therefore the description thereof will not be repeated.

[0051] [Series of processes] The sample manufacturing method according to one embodiment of the present invention preferably includes the above-mentioned first and second processing steps as a series of steps, and the series of steps is repeated multiple times in the reaction chamber 12. This makes it possible to suitably adjust the thickness of the metal oxide layer deposited on the surface of the observation target.

[0052] Moreover, it is more preferable that the method for producing a sample according to one embodiment of the present invention further includes the above-mentioned first and second purging steps in a series of steps, which can prevent the deposition of unreacted substances on the surface of the observation object, and can form a more uniform metal oxide layer on the surface of the observation object.

[0053] In other words, from the viewpoint of the thickness and uniformity of the metal oxide layer, it is preferable that the method for producing a sample according to one embodiment of the present invention includes a first treatment step, a first purging step, a second treatment step, and a second purging step as a series of steps, and that the series of steps is repeated multiple times.

[0054] When carrying out a series of steps, the temperature inside the reaction chamber 12 is preferably maintained within a range of 20° C. to 200° C., and more preferably within a range of 80° C. to 150° C., in order to favorably react the metal compound with the oxidizing agent, and the pressure inside the reaction chamber 12 is preferably maintained within a range of 200 mPa to 300 mPa.

[0055] Moreover, the series of steps is preferably repeated 10 to 30 times in order to form a metal oxide layer with a sufficient thickness.

[0056] [Effects of the manufacturing method of the sample] As can be understood from the above description, one aspect of the present invention relates to a method for manufacturing a sample for observing an object to be observed, which contains a reactive compound having reactivity with at least one target atmospheric component selected from the components in the atmosphere, excluding oxygen gas. According to one aspect of the present invention, a layer of metal oxide or metal is formed on the entire surface of the object to be observed, thereby manufacturing a sample including the object to be observed and a layer of metal oxide or metal. In the manufactured sample, the object to be observed is isolated from the atmosphere by the layer formed on the entire surface of the object to be observed, so that even if the sample is exposed to the atmosphere, the object to be observed does not denature or deform. Therefore, for example, even if a general-purpose device is used instead of a dedicated device such as an air-blocking sample holder, the object to be observed contained in the sample can be observed. Therefore, in the method for manufacturing a sample according to one aspect of the present invention, the restrictions due to the device used in observing the manufactured sample are relaxed compared to the prior art.

[0057] In one aspect of the present invention, when the method is carried out, each of the steps from the pretreatment step to at least the setting step to the second treatment step is carried out in an atmosphere that does not contain the target atmospheric component. Therefore, according to one aspect of the present invention, the object to be observed is not exposed to the target atmospheric component during the manufacturing process of the sample, so that denaturation and deformation of the object to be observed not only after manufacturing but also during the manufacturing process are prevented, and a sample suitable for observing the original structure and composition of the object to be observed can be manufactured.

[0058] <Sample> One aspect of the present invention relates to a sample for observing an object to be observed. The sample includes an object to be observed and a layer of metal oxide or metal formed on the entire surface of the object to be observed. The layer of metal oxide is, for example, HfO 2 , Al 2 O 3 , SiO 2 , ZrO 2 , or TiO 2 The metal layer may be a layer containing a metal such as Ti or Si. The sample according to one embodiment of the present invention may be manufactured by the method for manufacturing a sample according to one embodiment of the present invention described above.

[0059] Here, the thickness of the metal oxide or metal layer formed on the sample is preferably within a range of 0.5 to 2 nm, which allows the surface state of the observation target to be clearly observed when observing the sample using an electron microscope.

[0060] As described above, the sample produced by the production method according to one embodiment is suitably used as an observation sample, for example.

[0061] <Sample observation method> The sample manufactured using the sample manufacturing method according to one aspect of the present invention and the sample according to one aspect of the present invention can each be used to observe the structure or composition of an object to be observed. That is, the sample observation method according to one aspect of the present invention includes a manufacturing step of manufacturing a sample by carrying out the sample manufacturing method according to one aspect of the present invention, and an observation step of observing the object to be observed using the obtained sample.

[0062] The observation method used in the observation step is not particularly limited as long as it is a method that can observe the structure or composition of the observation target through a metal oxide or metal layer formed on the sample surface. Examples of the observation method include electron microscope observation, X-ray spectroscopy, and Raman spectroscopy. Among them, since it is possible to observe the structure and composition of a microscopic region having a size of about several nm to several μm, the observation method used in the observation step is preferably at least one selected from the group consisting of transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), energy dispersive X-ray spectroscopy (EDX), electron energy loss spectroscopy (EELS), and electron diffraction (ED), and more preferably one selected from the group consisting of EELS and STEM. Note that these methods can be used in any combination, and for example, the observation step may be performed by combining an electron microscope used for TEM or STEM with a detector used for one or more selected from EDX, EELS, and ED.

[0063] In TEM and STEM, the acceleration voltage is preferably within the range of 30 to 300 kV, which makes it possible to observe the structure and composition of a minute region of an object to be observed with higher detection sensitivity.

[0064] <Summary> As can be understood from the above explanation, the sample manufacturing method of aspect 1 of the present invention is a sample manufacturing method for observing an object to be observed, and includes an installation step of installing the object to be observed in a reaction chamber, a first processing step of forming a layer of the metal compound by adhering a gaseous metal compound to the entire surface of the object to be observed, and a second processing step of forming a layer of metal oxide or metal from the layer of the metal compound by reacting the metal compound with a gaseous oxidizing agent, wherein the object to be observed contains a reactive compound that is reactive to at least one target atmospheric component selected from components in the atmosphere excluding oxygen gas, and at least each of the steps from the installation step to the second processing step is performed in an atmosphere that does not contain the target atmospheric component.

[0065] A method for producing a sample according to a second aspect of the present invention is characterized in that, in the first aspect, the reactive compound is at least one selected from the group consisting of lithium oxide and lithium sulfide.

[0066] The method for producing a sample according to aspect 3 of the present invention is characterized in that, in aspect 1 or 2, the target atmospheric component is at least one selected from the group consisting of water vapor, carbon dioxide, carbon monoxide, nitrogen dioxide, nitrous oxide, and hydrogen sulfide.

[0067] A method for producing a sample according to a fourth aspect of the present invention is characterized in that, in any one of the first to third aspects, the gaseous oxidizing agent is ozone or oxygen plasma.

[0068] The method for producing a sample according to aspect 5 of the present invention is characterized in that, in any one of aspects 1 to 4, it further includes a pretreatment step of dispersing the object to be observed in a solvent or cutting out the object to be observed as a slice in an atmosphere not containing the target atmospheric component prior to the placement step.

[0069] The sample observation method according to aspect 6 of the present invention includes a manufacturing step of manufacturing a sample by carrying out the sample manufacturing method according to any one of aspects 1 to 5, and an observation step of observing the object to be observed using the sample.

[0070] A sample manufacturing method according to aspect 7 of the present invention is characterized in that in aspect 6, the observation step is carried out using at least one method selected from the group consisting of transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), energy dispersive X-ray spectroscopy (EDX), electron energy loss spectroscopy (EELS), and electron diffraction (ED).

[0071] <Additional Notes> The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. EXAMPLES

[0072] An embodiment of the present invention will be described below. In the embodiment and the comparative example of the present invention, Li 2 An electrolyte for an all-solid-state battery containing O as an active material was used as the observation subject, and samples were manufactured and observed.

[0073] <Example 1> An all-solid-state battery material (lithium oxide powder, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was obtained as the observation subject. The material sealed in a pouch was opened in a glove box under an argon atmosphere and dispersed on a Cu mesh.

[0074] A Cu mesh was fixed in the reaction chamber of an ALD apparatus (product name AT-400, manufactured by Anric Technologies) connected to a glove box, and an ALD process was performed to obtain a sample of Example 1 covered with a metal layer of about 2 nm. The conditions of the ALD process were as follows. A series of steps in which a precursor gas treatment step, a precursor gas purging step, an ozone gas treatment step, and an ozone gas purging step were consecutively performed was defined as one cycle, and 20 cycles were performed for a total of 30 minutes. Precursor gas: Trimethylaluminum (TMA) Oxidizing gas: O 3 Purge gas: N 2 Reaction chamber temperature: 150℃ Vacuum level inside reaction chamber: 225mPa Precursor gas treatment: 0.5 seconds, TMA flow rate 0.75 SCCM Precursor gas purge process: 8 seconds, purge gas flow rate 96 SCCM Ozone gas treatment: 0.5 seconds, ozone flow rate 0.75 SCCM Ozone gas purge process: 10 seconds, purge gas flow rate 96 SCCM

[0075] <Comparative Example 1> A sample of Comparative Example 1 was produced by the same method as in Example 1, except that the ALD treatment was not performed.

[0076] <Comparative Example 2> The sample of Comparative Example 2 was the same as the sample of Comparative Example 1. As described below, Comparative Example 2 was performed to evaluate the effect on observation by a dedicated air-tight sample holder.

[0077] (EELS observation) Each sample of Example 1 was placed on the sample stage of a general-purpose two-axis tilt sample holder (manufactured by JEOL Ltd.), and introduced into a transmission electron microscope ARM200F (manufactured by JEOL Ltd.) equipped with an EELS detector "QuantumER" (manufactured by GATAN), and each sample was observed using EELS. The accelerating voltage for observation was set to 200 kV, and the observation magnification was set to 1,000,000 times, and each observed sample was photographed.

[0078] The sample of Comparative Example 1 was observed in the same manner as the sample of Example 1. The sample of Comparative Example 2 was observed in the same manner as the sample of Example 1, except that a biaxial air-blocking sample holder (manufactured by JEOL Ltd.) was used instead of a general-purpose sample holder. EELS spectra obtained for each of the samples of Example 1, and Comparative Examples 1 and 2 are shown in FIG.

[0079] As shown in FIG. 2, in the EELS spectrum of the sample of Example 1, Li 2 Two peaks at 60.1 eV and 64.1 eV were confirmed, which are attributable to chemical bonds of O. In addition, in the EELS spectrum of the sample of Comparative Example 1, 2 CO 3 In the EELS spectrum of the sample of Comparative Example 2, two peaks were observed at the same positions as in the sample of Example 1, and the peaks were gentler than those in the sample of Example 1.

[0080] From the results shown in FIG. 2, it can be seen that the Li contained in the electrolyte was 2 O combines with atmospheric carbon dioxide and Li 2 CO 3 Therefore, it is understood that the original composition of the electrolyte could not be observed. 2 The denaturation of O is prevented by the metal oxide layer, and LiO 2was observed well. Such a prevention effect was comparable to that of Comparative Example 2, which used an air-blocking sample holder. In the EELS measurement of the sample in Comparative Example 2, the range of the tilt angle of the holder was small at ±5°, making it difficult to find a field of view suitable for the measurement. In contrast, in the EELS measurement of the sample in Example 1, the range of the tilt angle was large at ±25°, making it possible to find many fields of view suitable for the measurement, and the measurement could be carried out satisfactorily.

[0081] Furthermore, the sample holder used in Example 1 has a structure that allows the EDX detector to be brought closer to the sample in EDX measurement, compared to the sample holder used in Comparative Example 2. Therefore, when EDX measurement is performed on the sample of Example 1, it is considered possible to perform the measurement with higher sensitivity.

Claims

1. A method for producing a sample for observing an object to be observed, comprising the steps of: placing the observation object in a reaction chamber; a first processing step of depositing a gaseous metal compound on the entire surface of the object to be observed, thereby forming a layer of the metal compound; a second process step of forming a metal oxide or metal layer from the layer of metal compound by reacting the metal compound with a gaseous oxidizing agent; The object to be observed includes a reactive compound having reactivity with at least one target atmospheric component selected from atmospheric components other than oxygen gas, At least each of the steps from the placing step to the second treatment step is performed in an atmosphere not containing the target air component. Sample preparation method.

2. The reactive compound is at least one selected from the group consisting of lithium oxide and lithium sulfide. A method for producing a sample according to claim 1 .

3. The method for producing a sample according to claim 1 , wherein the target atmospheric component is at least one selected from the group consisting of water vapor, carbon dioxide, carbon monoxide, nitrogen dioxide, nitrous oxide, and hydrogen sulfide.

4. The gaseous oxidant is ozone or oxygen plasma. A method for producing a sample according to claim 1 .

5. The method further includes a pretreatment step of dispersing the object to be observed in a solvent or cutting the object to be observed into a slice in an atmosphere not containing the target atmospheric component before the placing step. A method for producing a sample according to claim 1 .

6. A manufacturing process for manufacturing a sample by carrying out the method for manufacturing a sample according to any one of claims 1 to 5; An observation step of observing the object to be observed using the sample. How to observe the sample.

7. The observation step is carried out using at least one selected from the group consisting of transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), energy dispersive X-ray spectroscopy (EDX), electron energy loss spectroscopy (EELS), and electron diffraction (ED); The method for observing a sample according to claim 6.

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