Sample holder tip and sample holder

Abstract

[Problem] The purpose of the present invention is to provide a sample holder capable of being observed in various manners. [Solution] A sample holder tip according to the present invention includes a sample stage where a sample and / or a sample mesh is mounted, a fixing part for securing the sample and / or sample mesh to the sample stage, and a voltage application unit for applying voltage to the sample, and said sample holder tip is characterized in that the voltage application unit is mounted on the sample stage. Furthermore, a preferred embodiment of the sample holder tip according to the present invention is characterized in that the voltage application unit is integrated with the sample stage.

Description

Sample holder tip and sample holder

[0001] The present invention relates to a sample holder tip and a sample holder used for sample visualization, image formation, analysis, etc., and more particularly to a sample holder tip and a sample holder used for sample observation under vacuum.

[0002] The need to observe and analyze samples at the molecular and atomic level has led to the need for electron microscopy, which combines highly accurate imaging and analytical techniques under harsh conditions. For example, transmission electron microscopes (TEMs) are used to observe samples under ultra-high or high vacuum.

[0003] As a sample holder for positioning a sample at an observation position of a TEM, for example, a sample holder for a transmission electron microscope is known (Patent Document 1), which comprises: a sample holder body having a first opening with a step formed therein; a sample holding member that is rotatably housed within the first opening by having a portion of its periphery supported by the step and has a second opening in its center for holding the sample; and a cover member that has an amorphous material film that covers the second opening except for at least a portion of the second opening.

[0004] Also known is a cryogenic sample holder for storing, cooling, and positioning a sample in at least one imaging and analysis device, characterized in that it includes a container for storing and holding the sample, a storage container for storing a liquid cooling medium having a collection point for the liquid cooling medium, a thermal conductor that is in thermal contact with the liquid cooling medium and the container regardless of the amount of the liquid cooling medium in the container and the spatial orientation of the storage container, the thermal conductor being in adjacent surface contact with the liquid cooling medium at the collection point, and an elongated barrel attached between the storage container and the container to position the sample at a preselected location in at least one of the imaging and analysis devices (Patent Document 2).

[0005] JP 2007-179805 A JP 2013-537689 A

[0006] Conventional TEM sample holders, including the one described in Patent Document 1, require the separation of the atmosphere and vacuum sides to prevent vacuum leakage through the holder within the TEM. Because observations with a transmission electron microscope are performed under high vacuum (high vacuum is preferred), it is necessary to locate the vacuum / atmosphere partition (sealing surface) as close to the tip of the holder as possible to minimize the volume or surface area to be evacuated. This results in spatial constraints on the design, as the sample holder tip shaft either has a small diameter or the inner diameter is reduced due to the presence of a sealing member (e.g., an O-ring).

[0007] Furthermore, in recent years, as we strive for a decarbonized society, the shift to electric vehicles is progressing worldwide, and research and development into lithium-ion batteries is being conducted accordingly.Until now, due to various physical factors, it has been difficult to observe lithium-ion batteries under an electron microscope, and even leading companies both in Japan and overseas have been unable to achieve this.

[0008] Although a battery needs electricity to operate, as mentioned above, it was difficult to even observe a battery with an electron microscope, and it was even more difficult to pass electricity through it.

[0009] As described above, improvements in analytical technology and analytical demands have led to the need for specimen observation under a variety of conditions and environments. However, to meet these demands, sufficient space is required within the specimen holder, but in the past, it was difficult to secure sufficient space due to the aforementioned common sense in design.

[0010] In order to solve the above problems, an object of the present invention is to provide a sample holder that allows various observations.

[0011] In order to achieve the above object, the present inventors have conducted extensive research into the degree of freedom in designing a device that can ensure a high vacuum, and as a result have come up with the present invention.

[0012] In other words, the sample holder tip of the present invention is a sample holder tip having a sample stage for mounting a sample and / or sample mesh, a fixing portion for fixing the sample and / or sample mesh to the sample stage, and a voltage application portion for applying a voltage to the sample, and is characterized in that the voltage application portion is mounted on the sample stage.

[0013] In a preferred embodiment of the tip of the sample holder of the present invention, the voltage application unit is integrated with the sample stage.

[0014] In a preferred embodiment of the sample holder tip of the present invention, the sample and / or sample mesh is mounted on the sample stage via a tip or cartridge.

[0015] In a preferred embodiment of the tip of the sample holder of the present invention, the tip or cartridge has an electrode terminal.

[0016] In a preferred embodiment of the tip of the sample holder of the present invention, the tip further comprises a seal portion located further toward the center of the axis of the electron microscope than the sample stage.

[0017] In a preferred embodiment of the tip of the sample holder of the present invention, it is further characterized by having an offset cam mechanism.

[0018] The sample holder of the present invention is characterized by having the sample holder tip of the present invention.

[0019] The sample holder of the present invention is characterized by having a sample holder shaft having the sample holder tip of the present invention, an outer cylinder capable of storing the sample holder shaft, a sample holder handle attached to the sample holder shaft on the opposite side of the sample holder tip, and a support part through which at least an electrode or a flow path passes, at a position further outward from the center than the goniometer stage position of the electron microscope when the sample holder is attached to the electron microscope.

[0020] In a preferred embodiment of the sample holder of the present invention, the sample holder shaft portion has a groove.

[0021] In a preferred embodiment of the sample holder of the present invention, the tip of the sample holder is retractable into the outer cylindrical portion.

[0022] In a preferred embodiment of the sample holder of the present invention, the sample holder further comprises a cooling section capable of cooling the shaft section of the sample holder.

[0023] In addition, in a preferred embodiment of the sample holder of the present invention, when the sample holder is installed in an electron microscope, a partition member that isolates the inside of the outer cylindrical portion from the atmosphere is provided at a position further outward from the center than the position of the goniometer stage of the electron microscope.

[0024] In a preferred embodiment of the sample holder of the present invention, the partition member is disposed at a connection between the outer cylindrical portion and the sample holder handle portion.

[0025] In a preferred embodiment of the sample holder of the present invention, the sample holder shaft portion is rotatable about the sample holder shaft.

[0026] In addition, in a preferred embodiment of the sample holder of the present invention, the rotation is characterized in that the sample can be rotated around the axis of the sample holder shaft portion or around an axis perpendicular to the axial direction of the sample holder shaft portion.

[0027] The sample holder tip of the present invention has a voltage application unit mounted on the sample stage, which advantageously prevents the electrode probe from slipping when the sample is tilted during tilted observation, eliminating problems such as vibration causing the sample image to shake. The sample holder of the present invention also has the advantageous effect of being able to isolate the sample and / or sample mesh mounting area from the atmosphere during transfer, thereby functioning as a transfer holder. The sample holder of the present invention also has the advantageous effect of being able to evacuate the sample holder using the vacuum evacuation on the electron microscope side.

[0028] FIG. 1 is a side cross-sectional view of a sample holder according to one embodiment of the present invention. FIG. 2 is a side cross-sectional view of a sample holder according to one embodiment of the present invention (when the sample holder tip is retracted). FIG. 3 is a perspective view of a sample holder according to one embodiment of the present invention. FIG. 4 is a perspective view of a sample holder tip according to one embodiment of the present invention. FIG. 5 is a perspective view of a sample holder tip according to one embodiment of the present invention. FIG. 6 is a side cross-sectional view of a sample holder tip according to one embodiment of the present invention. FIG. 7 is a top view of a sample holder tip according to one embodiment of the present invention. FIG. 8 is a perspective view of a conventional sample holder tip. FIG. 9 is a side cross-sectional view of a conventional sample holder tip.

[0029] The sample holder tip of the present invention comprises a sample stage for mounting a sample and / or a sample mesh, a fixing portion for fixing the sample and / or the sample mesh to the sample stage, and a voltage application portion for applying a voltage to the sample, wherein the voltage application portion is mounted on the sample stage. In the present invention, the sample stage for mounting the sample and / or the sample mesh is not particularly limited, and may be a sample stage for mounting only the sample. The fixing portion for fixing the sample and / or the sample mesh to the sample stage is also not particularly limited, and may be any portion capable of fixing the sample to the sample holder tip. As described below, if the sample is carried using a chip or cartridge, the chip or cartridge may be used for fixing the sample. The voltage application portion allows for observation of the sample even when an electric current is applied, in response to the recent demand for sample observation under various conditions and environments. Because the voltage application portion is mounted on the sample stage on which the sample is also mounted, image fluctuations, as previously described, can be minimized.

[0030] In a preferred embodiment of the tip of the sample holder of the present invention, the voltage application unit is integrated with the sample stage.

[0031] Conventional voltage application units are not mounted on the sample stage but are installed in a device that is driven separately from the sample stage. For example, existing two-axis tilting current holders use a spring 81 for tilting. Because the tilt of the sample pedestal (cradle) 90 and the electrodes are separate (see Figures 8 and 9), the electrodes and the chip 91 (commonly known as a MEMS chip) for applying electricity are installed separately from the tilting mechanism. As the sample tilts, the electrode probes 80 and 92 (needles) slide over the electrodes. Because the rotating cradle 90 and the electrodes are separate, tilting the cradle 90 displaces the electrode probe 92, transmitting vibrations that result in image fluctuations. Furthermore, because the spring 81 restores the tilt, the entire diameter of the narrow holder shaft is required. Furthermore, because the holder is driven separately from the electrodes, it is impossible to provide an air-shielding function, i.e., a retraction function. Furthermore, because the tip 91 and the electrode probe 92 are driven separately, the structure has had various problems in the past, making it almost impossible to achieve a function of not exposing to the atmosphere. However, surprisingly, in the present invention, the voltage application unit is mounted on the sample stage in addition to the sample, which not only solves the problem of image shaking, but also makes it possible to achieve compactness, and ultimately makes it possible to store the tip of the sample holder, thereby achieving a function of not exposing to the atmosphere.

[0032] In a preferred embodiment of the sample holder tip of the present invention, the sample and / or sample mesh is mounted on the sample stage via a chip or cartridge. The sample can be placed on the chip or cartridge, and the chip or cartridge can be fixed to the sample stage.

[0033] In a preferred embodiment of the tip of the sample holder of the present invention, the tip or cartridge has an electrode terminal. In this invention, the voltage application unit is disposed on the sample stage, so that the electrodes from the voltage application unit can be brought into contact with the electrode terminals from the tip or cartridge to conduct electricity. In this case, the electrode terminals can be used to fix the tip or cartridge to the sample stage, and thus the sample can also be fixed to the sample stage.

[0034] In a preferred embodiment of the specimen holder tip of the present invention, the specimen holder tip further includes a seal located closer to the center of the electron microscope axis than the specimen stage. The seal allows for vacuum evacuation of the specimen holder without creating a barrier when using the electron microscope's vacuum pumping function during specimen observation, as described below. Furthermore, when transporting the specimen holder, the seal can isolate the inside of the specimen holder from the outside air when storing the specimen holder tip, thereby enabling the specimen holder to be used as a transfer holder. As a seal having a similar function, a seal on the outer cylinder of the specimen holder closer to the center of the electron microscope can also be installed, as described below. The presence of a seal on at least one of the specimen holder tip or outer cylinder allows for the above-mentioned atmospheric exposure function.

[0035] In the present invention, the sample and voltage application unit can be mounted on the sample stage, thereby achieving a small footprint. If the TEM holder is large and there is sufficient space within the electron microscope, storage is not a problem. However, if a spring-type holder is used, as in the conventional method described above, the sample holder becomes large in the longitudinal direction and on both sides, and the tilting structure becomes complex, making it very difficult to use the tip of the holder as a storage axis. Furthermore, when storing the tip, a sealing surface is required to prevent exposure to the atmosphere and ensure vacuum transfer. However, using existing technology, a spring or other device is required, making it physically difficult to store the tip on the axis of a thin TEM holder.

[0036] Furthermore, if the specimen holder shaft is large, it is possible to incorporate the entire shaft of a conventional non-exposed holder into a chamber in the holder handle, but this would result in the loss of the ability to retract only the tip. Retracting the specimen holder handle would more than double the overall length of the holder when retracted, resulting in poor usability, increased vibration, and potential leaks (vacuum breakdown) and reduced reliability of the retracted seal. Furthermore, this would make the holder too large to fit into a standard glove box, and it would be impossible to achieve non-exposed atmosphere with an FEI (thin shaft, as in the current Thermo Fisher microscope). However, the present invention allows the specimen and voltage application unit to be mounted on the specimen stage, thereby minimizing the space required for the electrode-equipped specimen base and tip, and achieving retraction even on a thin holder shaft, specifically a 7mm diameter.

[0037] Furthermore, a preferred embodiment of the specimen holder tip of the present invention is characterized by further comprising an offset cam mechanism. In the present invention, the offset cam mechanism is not particularly limited, and a conventional mechanism can be used. The specimen holder tip of the present invention is equipped with a camshaft, and by rotating the specimen holder shaft, the camshaft also rotates, and the specimen stage can be tilted. By rotating the camshaft, the specimen can be rotated around an axis perpendicular to the axial direction of the specimen holder shaft. The specimen holder shaft can also be rotated by rotating the handle.

[0038] The sample holder of the present invention is characterized by having the sample holder tip of the present invention. The above description can be referred to for the sample holder tip that can be used for the sample holder of the present invention.

[0039] The present invention also provides a sample holder comprising a sample holder shaft having the sample holder tip of the present invention, an outer cylinder capable of storing the sample holder shaft, a sample holder handle attached to the sample holder shaft on the opposite side of the sample holder tip, and a support portion through which at least an electrode or a flow channel can pass, the support portion being positioned outward from the center of the goniometer stage of the electron microscope when the sample holder is attached to the electron microscope. The above description can be referred to for the sample holder tip that can be used with the sample holder of the present invention.

[0040] In the present invention, a seal may be provided at the tip and / or outer casing of the sample holder. By providing a seal at the tip and / or outer casing of the sample holder, the sample holder can be evacuated without becoming a barrier when using the vacuum exhaust on the electron microscope side during sample observation, and when transporting the sample holder, the inside of the sample holder can be isolated from the outside air when storing the tip of the sample holder, which has the advantageous effect of allowing it to be used as a transfer holder.

[0041] Furthermore, in the present invention, when the sample holder is installed in an electron microscope, a support portion through which at least an electrode or a flow path passes can be provided at a position further outward from the center than the position of the goniometer stage of the electron microscope. In the present invention, the support portion is not particularly limited as long as it can pass at least an electrode or a flow path. The support portion can also support the sample holder shaft portion, and when a cooling portion as described below is used, can be capable of transferring heat from the cooling portion. Furthermore, when a cooling portion is not required, the support portion can also be used in combination with a barrier member as described below.

[0042] In a preferred embodiment of the sample holder of the present invention, the sample holder shaft has a groove. In the present invention, for example, when applying current, the groove can be cut along the axis, and wiring can be fixed to the groove and linked to the shaft. For example, as described below, when storing the tip of the sample holder, the wiring can be smoothly stored together with the groove.

[0043] In a preferred embodiment of the sample holder of the present invention, the tip of the sample holder can be stored in the outer tube. When the tip of the sample holder is stored in the outer tube, a seal at the tip of the sample holder and / or the outer tube can isolate the inside of the sample holder from the outside air, thereby allowing the sample holder to function as a transfer holder. The seal does not act as a barrier when using vacuum evacuation on the electron microscope side during sample observation, and therefore its role differs from that of conventional seals, even if their location is similar.

[0044] In other words, in the past, due to excessive emphasis on vacuum and due to polishing technology and other factors, it was common technical knowledge that the seal position should be as close to the front of the specimen holder (towards the center of the microscope) as possible.However, in conventional technology, the idea of ​​using vacuum exhaust on the electron microscope side did not exist, and from the perspective of reducing the volume to be evacuated, it was assumed that the seal would be located as close to the tip of the holder as possible, and that a separate vacuum would be drawn from the specimen holder handle side of the seal.

[0045] In conventional technology, the seal remains active throughout the entire process, making it impossible to utilize the vacuum exhaust on the electron microscope side. However, in the present invention, when observing a sample, the tip of the sample holder is not stored in the outer tube, so the seal does not function, allowing the vacuum exhaust on the electron microscope side to be utilized. However, when the tip of the sample holder is stored, the seal can still function as a seal, and therefore the holder can also be used as a transfer holder.

[0046] In a preferred embodiment of the sample holder of the present invention, the sample holder further comprises a cooling unit capable of cooling the sample holder shaft. The location of the cooling unit is not particularly limited. More specifically, the cooling unit can be located, for example, in the direction of the handle of the sample holder, preferably in front of the handle. The cooling unit can use liquid nitrogen, liquid helium, or the like to cool the sample holder shaft and, ultimately, the sample.

[0047] Furthermore, the Dewar evacuation method using the sample holder, which is an example of a preferred embodiment of the present invention, makes it possible to draw a vacuum in the entire TEM, etc. That is, the evacuation method of the present invention is characterized by using the vacuum evacuation on the TEM side to draw a vacuum.

[0048] The method for evacuating the Dewar part of an existing cooling holder (specimen holder) is as follows: 1. Heat the Zeolite 95 for about 3 hours while drawing a vacuum. Wait about 3 hours for it to return to room temperature. 2. Insert the specimen holder into a TEM or similar. 3. Pour liquid nitrogen into the cooling container. 4. By adding liquid nitrogen, the Zeolite 95 adsorbs the molecules, and by increasing the degree of vacuum in the Dewar, it provides vacuum insulation and cooling.

[0049] However, existing methods for maintaining a vacuum in the Dewar section suffer from the following problems: 1. The adsorption capacity of zeolite gradually decreases over cooling time. There is a limit to the number of times liquid nitrogen can be refilled. 2. Because the vacuum level is unstable, heat transfer from the outside to the axis changes over time, resulting in unstable thermal drift. This makes it difficult to acquire data due to thermal drift when using high-resolution (atomic resolution) instruments such as TEM. 3. Furthermore, vacuum insulation is required between the TEM and Dewar sides, which requires a seal. However, heat flows into the axis from this seal, which also contributes to thermal drift. Furthermore, heat input increases the time required to cool the instrument and raises the ultimate temperature. 4. Because the adsorption capacity of the zeolite saturates, vacuum heating of the zeolite is required after observation, which takes approximately six hours from the end of observation to the next observation.

[0050] In contrast, as described above, the Dewar vacuum method using the sample holder of the present invention makes it possible to draw a vacuum in all TEMs, etc. That is, the vacuum drawing method of the present invention is a method of drawing a vacuum in the sample holder of the present invention inside an electron microscope, and is characterized by using the vacuum exhaust on the electron microscope side to draw a vacuum.

[0051] The advantages of the vacuum method using the sample holder of this example of the present invention are as follows: 1. There is no need to use a seal, and there is no need to separately draw a vacuum on both the cooling side and the tip side of the sample holder. Consequently, the same vacuum level can be maintained throughout, eliminating the effects of uneven radiant heat (heat from the external environment). (All radiant heat is uniform.) 2. Because there are no seals along the way, heat input from the TEM or other equipment is extremely low. 3. Due to the aforementioned advantages, the temperature stability of the heat transfer shaft is significantly improved, reducing the effects of thermal drift. This vacuum method reduces the heat input to the sample holder and the effects of radiant heat, enabling stable acquisition of high-resolution images even during cooling. 4. Additional benefit: In TEMs and other instruments, the preparatory process of overheating and vacuuming zeolite is no longer necessary because all vacuums are drawn. The sample holder of this invention can be cooled immediately after returning to room temperature, allowing for multiple observations per day.

[0052] Strictly speaking, the absence of a seal means that, when observing a sample, the tip of the sample holder is not retracted into the outer tube of the sample holder, and the seal that separates the inside and outside of the sample holder is not functioning. This means that the sample holder is not sealed, making it possible to evacuate the entire interior of the sample holder in a TEM or other instrument. When using vacuum evacuation on the electron microscope side during sample observation, a seal (also called a second seal or barrier member) that seals the motor connecting shaft can be installed just before the handle or between the cooling dewar casing and the retracting handle. This allows the inside of the sample holder to be evacuated using the vacuum on the electron microscope side while isolating it from the outside air. Alternatively, the seal may be located between the holder shaft and the cooling dewar casing. While the seal is typically located on the outside of the holder shaft, the former is preferred as an embodiment.

[0053] The material for the seal or the partition member described below can be polytetrafluoroethylene or a high-performance fluorinated rubber material such as fluorosilicone. Polytetrafluoroethylene has very high cold resistance and also high thermal insulation. Therefore, if the seal is made of a cold-resistant material, observations can be performed under cooled conditions under a securely sealed condition.

[0054] In a preferred embodiment of the sample holder of the present invention, at least a portion of the support can transfer heat from the cooling unit to the sample holder shaft. The support can be in contact with the cooling unit. In this case, heat from the cooling unit can be transferred to the sample holder shaft. In this case, the support not only supports the sample holder but also transfers heat from the cooling unit to the sample holder shaft. In the present invention, the material of the support when conducting heat is not particularly limited as long as it can efficiently conduct heat, and examples include copper alloy, pure copper, A7075, etc. Other materials that can be used include copper mixed with (STC) carbon and any material with good thermal conductivity that can be machined.

[0055] The cooling unit may also include a heat-conducting portion. For example, when liquid nitrogen or the like is used, the cooling unit can be configured to connect the bottom of the liquid nitrogen container to the sample holder shaft with a heat-conducting portion made of a heat-conducting material. This allows the liquid nitrogen temperature to be transferred to the sample holder shaft and ultimately to the sample until the liquid nitrogen is completely depleted. When a support portion is also used, a portion of the support portion serves as a heat-conducting portion, allowing the heat from the cooling unit to be transferred to the sample holder shaft as described above. Thus, when the present invention is applied to a cooling holder, the coolant in the Dewar portion can be retained longer, and a high vacuum can be maintained with stable heat transfer, resulting in the advantageous effect of improving temperature stability.

[0056] In a preferred embodiment of the specimen holder of the present invention, when the specimen holder is installed in an electron microscope, a partition member is provided that separates the interior of the outer cylindrical portion from the atmosphere, located at a position further outward from the center than the goniometer stage of the electron microscope. In the present invention, locating the partition member at a position further outward from the center than the goniometer stage of the electron microscope offers various advantages. Specifically, in the past, due to factors such as polishing technology, the sealing position needed to be located as close to the front of the specimen holder (toward the center of the microscope) as possible. This is because the inner wall of the specimen holder needs to be polished, which is difficult. Therefore, due to the need to polish the minimum surface area, it was generally conceived to locate the sealing position closer to the front of the specimen holder (toward the center of the microscope). In reality, the farther the sealing position is, the more likely it is to cause malfunctions of the microscope, specimen holder, and other devices. The partition member is not particularly limited as long as it can separate the interior of the outer cylindrical portion from the atmosphere. Examples of partition members include sealing members, sealing members, and more specifically, O-rings.

[0057] In the present invention, in the embodiment in which a seal is present for storing the tip of the sample holder, the seal does not function during sample observation and does not interfere with vacuuming on the electron microscope side, which is significantly different from the role of conventional seals.

[0058] In the present invention, by arranging the partition member at a position further outward from the center of the electron microscope than the position of the goniometer stage of the electron microscope, it becomes possible to effectively utilize the internal space between the specimen holder shaft and the outer cylinder, which has conventionally been the case due to the presence of a barrier member, making it impossible to effectively utilize the space.

[0059] Furthermore, by arranging the partition member at a position outside the goniometer stage of the electron microscope, as will be described later, when the barrier member is used in combination with a hermetic seal or the like, it is possible to effectively utilize the relatively large space located outside the goniometer stage of the electron microscope. This allows for greater design freedom and ultimately improved performance of the sample holder itself. Specifically, the present invention dramatically improves the performance of sample holders incorporating electrodes, sample holders incorporating flow channels, and cooling sample holders. In other words, the present invention effectively utilizes the large space inside the shaft and can be arranged in a relatively large space outside, thereby utilizing the space around the partition member, thereby achieving advantageous effects such as greater design freedom and significantly improving the ease of wiring and other work.

[0060] In other words, in the past, due to excessive emphasis on vacuum and due to considerations of polishing technology, etc., it was common technical knowledge that it was essential to position the seal as close to the front of the sample holder (towards the center of the microscope) as possible.However, contrary to this common technical knowledge, we attempted a change of thinking and came up with the present invention.

[0061] The sample holder to which the present invention can be applied is not particularly limited. For example, the present invention can be applied to a single-axis tilt sample holder, a two-axis tilt sample holder, an electric field holder, a magnetic field holder, a heating holder, or a so-called cooling sample holder having a cooling unit, or a cooling holder with a two-axis tilt mechanism.

[0062] In a preferred embodiment of the present invention, the outer wall surface of the sample holder shaft and the inner wall surface of the outer cylinder can be mirror-finished. The outer wall surface of the sample holder shaft and the inner wall surface of the outer cylinder of the present invention can be mirror-finished, and by adopting such a configuration, it is possible to obtain the advantages described below in so-called "vacuum drawing."

[0063] Depending on the shape and specifications of the specimen holder components, the mirror finish may be performed using, for example, buffing, hand polishing, or other polishing methods, or a combination of multiple polishing methods. The mirror finish preferably includes internal steps, bores, screw holes, grooves, and other fine areas not previously considered. Furthermore, the surface roughness achieved by the mirror finish, in terms of arithmetic mean roughness (Ra), is preferably in the range of 0.2 μm to 1 μm, and more preferably not exceeding 0.2 μm. Polishing the inside of the holder shaft to a mirror finish in this way advantageously avoids placing excessive strain on the TEM's vacuum pumping system and allows for the achievement of the specified high vacuum.

[0064] In a preferred embodiment of the present invention, the partition member may be installed at a connection between the outer cylinder and the sample holder handle. There are no particular limitations on the location of the partition member as long as it can be located at a position further outward from the center of the electron microscope than the position of the goniometer stage of the electron microscope, but installing the partition member at the connection makes it possible to ensure more space inside the shaft and in the handle.

[0065] In a preferred embodiment of the present invention, the partition member may be installed inside the sample holder handle. In this case, the hermetic portion is virtually free of spatial constraints, allowing for a wider and larger design. While the term "hermetic" generally refers to an airtight sealing structure that blocks external air, in the present invention it is interpreted more broadly and can be used as a support member for passing electrodes, flow paths, etc. The partition member may also serve as a hermetic member, allowing at least electrical wiring or fluid piping to pass through it. While this was previously nearly impossible due to the sample holder's operating conditions (heating, fluid flow, application of an electric field, light / laser irradiation, and combinations thereof) corresponding to the sample observation conditions, the present invention allows for the passage of a total of eight or more electrical wiring and fluid piping lines through the hermetic member.

[0066] In a preferred embodiment, the sample holder shaft can be made rotatable around the sample holder shaft. This is also called X-axis tilt, α-tilt, or uniaxial tilt. Generally, this can be performed using a device on the TEM side, but in the present invention, X-axis tilt is also possible on the sample holder side. By making the sample holder rotatable around the shaft, the sample and / or sample mesh mounting part can also be made rotatable around the shaft, making it possible to observe the sample while it is rotated. Rotation can be performed by any conventional method and is not particularly limited. More specifically, for example, rotation can be performed using the handle part of the sample holder.

[0067] In a preferred embodiment of the present invention, the rotation allows the sample and / or sample mesh mounting portion to rotate around the axis of the sample holder shaft portion as described above, as well as around an axis perpendicular to the axial direction of the sample holder shaft portion. The mechanism for allowing rotation around an axis perpendicular to the axial direction of the sample holder shaft portion may be a conventional mechanism and is not particularly limited. In a preferred embodiment, the rotation around the axis perpendicular to the axial direction of the sample holder shaft portion may be performed via an offset cam mechanism.

[0068] Even when the specimen holder is for cooling, the position of the partition member is not particularly limited. The partition member can be installed at any location, such as the connection between the cooling unit (Dewar unit) and the handle unit, near the connection between the cooling unit and the outer cylinder unit toward the center of the microscope, or at the bottom, middle, or top of the Dewar unit.

[0069] Furthermore, by incorporating a MEMS (Micro Electro Mechanical System) chip, the specimen to be observed can be subjected to heating, current application, tension, and other conditions, each without exposure to air and under cooling. This allows observations to be performed while controlling basic physical quantities using a single holder. Note that MEMS (Micro Electro Mechanical System) chips are an abbreviation for microelectromechanical systems, a general term for devices in which mechanical elements such as sensors, actuators, and heaters are integrated into a microscopic area on a semiconductor substrate such as silicon or a glass substrate using microfabrication techniques. Conventional methods can be incorporated into the present invention, without particular limitations. Electrical circuits and mechanical structures are incorporated within micron-sized areas, and in the field of electron microscopy, in particular, they are an effective method for reproducibly controlling physical parameters such as current application, heating, and stress application on specimens measuring several micrometers to several millimeters under constraints such as small spaces and high vacuum conditions. Conventional methods can also be applied to the present invention.

[0070] In addition, in the case of heating, the chip can be heated by forming a heater pattern on the chip and passing an electric current through it. The heater pattern can be a conventional one and is not particularly limited, and examples thereof include a spiral, wave, honeycomb, etc. As the heater pattern, a pattern that cancels out magnetic fields generated by current flow and a pattern that heats evenly are desirable.

[0071] In addition, when applying electricity, by creating a pattern of electrodes (positive and negative) on both sides of a space such as a slit, placing the sample across the slit (any suitable space will do) and applying voltage, it is possible to apply voltage between the electrodes or pass current through the electrodes.

[0072] In the case of tension, a tensile stress can be applied to a sample by creating an actuator that operates when electricity is passed through it and patterning it into a chip shape.

[0073] While the following describes examples of the sample holder of the present invention with reference to the drawings, the present invention is not limited to these examples and can, of course, be modified as needed without departing from the spirit and scope of the present invention.

[0074] FIG. 1 is a side cross-sectional view of a sample holder according to one embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a seal portion, 2 denotes a sample holder shaft (rotation axis), 3 denotes a current-carrying wire, 4 denotes a current-carrying wire extension / retraction portion, 5 denotes an outer cylinder portion, 6 denotes a vacuum region, 7 denotes a support portion, 8 denotes a cooling portion (Dewar portion), 9 denotes a second seal portion, 10 denotes a shaft-tilting motor, and 11 denotes a handle portion. Although not shown, a sample mounting portion is located between the handle side of the seal portion 1 and the tip of the outer cylinder portion 5 on the electron microscope side. Alternatively, the sample mounting portion may be a sample mesh mounting portion, or a combination of a sample mounting portion and a sample mesh mounting portion may be used. When the sample holder tip is retracted, the spring-shaped current-carrying wire extension / retraction portion 4 can be extended and retracted.

[0075] FIG. 1 is a schematic diagram of a sample during observation. When the sample holder is set in the electron microscope, a vacuum region 6 equivalent to the vacuum of the TEM can be achieved by utilizing the vacuum pumping on the electron microscope side (TEM). For example, as shown in the figure, a second seal 9 can be installed outside the electron microscope goniostat. When using the vacuum pumping on the electron microscope side (TEM), the vacuum region 6 can be the same as the vacuum of the TEM. The second seal (also called a barrier member) can be located, for example, just before the handle 5, inside the handle 5. However, the closer the seal position is to the handle 11 from the outer tube 5, the larger the space becomes, which increases the so-called vacuum volume and places a strain on the TEM's vacuum pumping system. In other words, in conventional configurations where a seal member is installed at the tip, simply moving the seal closer to the handle makes it increasingly difficult to achieve the specified vacuum. However, this can be addressed by polishing the inside of the holder shaft to a mirror finish to a level that does not cause problems with vacuum pumping. Mirror finishing will be described in more detail below.

[0076] In the embodiment of the present invention, liquid nitrogen is used as the refrigerant in the container of the cooling unit (Dewar unit) 8 .

[0077] In addition, in a mode where cooling is possible, a cooled refrigerant can be used. For example, when liquid nitrogen is used, if a normal O-ring is used in a normal manner, the O-ring will harden at the liquid nitrogen temperature, and the metal will shrink as the temperature drops, making it impossible to achieve a vacuum seal (external seal) with a sample holder that uses liquid nitrogen temperature.

[0078] However, if a cold-resistant material such as polytetrafluoroethylene is used as the sealing material, the sealing performance will be excellent even under liquid nitrogen, since polytetrafluoroethylene sealing materials are durable down to temperatures of -200°C or below.

[0079] Figure 2 shows a side cross-sectional view of a sample holder according to one embodiment of the present invention. In Figure 2, 1 denotes a seal portion, 4 denotes an expandable current-carrying wiring portion, 6 denotes a vacuum region, and 11 denotes a handle portion. Figure 2 shows the sample holder tip containing the sample stored within the outer cylindrical portion of the sample holder. By storing the sample holder tip at the tip, the vacuum region 6 can be maintained with argon or vacuum, and vacuum transfer is also possible. As shown in Figures 1 and 2, the handle portion 11 can be moved parallel to the longitudinal direction of the sample holder, allowing the sample holder tip to be stored along with the wiring. In this way, the inside of the dewar and the TEM holder can be maintained at the same vacuum. Furthermore, as described below, it is possible to provide a feedthrough in the dewar portion. This allows for electrical conduction, cooling, biaxial tilting, and atmospheric non-exposure to be achieved with a single sample holder.

[0080] Figure 3 is a perspective view of a sample holder according to one embodiment of the present invention. In Figure 3, 1 denotes a seal portion, 5 denotes an outer cylinder portion, 8 denotes a cooling portion (Dewar portion), 11 denotes a handle portion, and 20 denotes a feed-through portion. Figure 3 shows a sample holder with the tip not retracted, with the seal portion 1 visible. In this embodiment, a feed-through portion for wiring can be provided on the Dewar side. In this embodiment, an electrode can be placed at the tip while maintaining the retracted, i.e., non-exposed to the atmosphere, function. In this case, the structure of the electrode is not particularly limited.

[0081] In this example, the field-through (hermetic) section is provided on the cooling section side, but the second seal section and / or field-through section may be provided at the connection between the outer cylinder and the sample holder handle. In this case, the sample holder shaft (rotation axis) and the lead wires can pass through the hermetic section. Depending on the conditions of use of the sample holder (heating, fluid flow, application of an electric field, light / laser irradiation, or a combination thereof), multiple components can pass through the hermetic section.

[0082] Furthermore, although not shown, a sealing surface including a second sealing portion may be provided further back in the handle portion. The second sealing portion may also be part of the hermetic seal. In this example, by locating the sealing surface in a larger space outside the goniophotometer of the electron microscope, there are almost no spatial constraints on the hermetic seal, allowing for a larger and wider design. When introducing a fluid (gas, liquid) into the holder, a pipe or the like may be incorporated as a flow path, but the structure of this example allows for easy design without worrying about interference with the flow path and / or electrodes and related components.

[0083] On the other hand, as the sealing surface is moved further away from the center of the electron microscope outside the gonioscope, the volume of the vacuum pumped by the electron microscope increases, which may place a strain on the vacuum pumping system of the electron microscope.

[0084] In such cases, a high vacuum can be achieved by polishing the inside of the holder shaft to a mirror finish over as wide an area as possible. In this case, it is preferable to mirror-finish at least the inner surface of the outer cylinder. The mirror-finished area should include small areas that have not been covered in the past, such as internal steps, and the smaller the area that is not mirror-finished, the better.

[0085] Depending on the shape and specifications of the sample holder components, mirror finishing may be performed by, for example, buffing, hand polishing, or other polishing methods, or by a combination of multiple polishing methods. Furthermore, it is preferable that the surface roughness of the mirror finish does not exceed 0.2 μm in terms of arithmetic mean roughness Ra. If Ra exceeds 1, it becomes practically difficult to continue evacuating the Dewar section using the TEM's evacuation system. In other words, if Ra exceeds 1, it will take a long time to evacuate the Dewar section using the TEM's evacuation system, which may cause practical inconvenience.

[0086] Next, we will explain how to perform so-called vacuum pumping using the sample holder of the present invention in a TEM. In particular, we will explain an example in which the sample holder of the present invention is used for cooling samples. When performing the Dewar vacuum method on the sample holder of the present invention, the area covered by the vacuum is as shown by the vacuum region 6 in Figure 1 . That is, the area covered by the vacuum in the sample holder of the present invention is expanded as shown by region 6 in Figures 1 and 2 . When the entire sample holder is vacuum pumped in a TEM, a practically uniform vacuum level can be maintained throughout the entire region between the shaft and the outer cylinder from the inside of the Dewar housing, eliminating the impact of uneven radiant heat on the sample holder. In other words, the radiant heat received by the sample holder is substantially uniform. Furthermore, since the outer cylinder does not have a seal portion as in the prior art, heat input to the sample holder 10 from devices such as a TEM can be significantly reduced. Furthermore, the sample holder of the present invention does not require the preparatory heating and vacuum pumping of Zeolum, which was previously required in the prior art.

[0087] Furthermore, when the specimen holder of the present invention is used for cooling, the inside of the dewar can be made to have the same degree of vacuum as that of a microscope, which not only improves the retention of liquid nitrogen, but also, when a heat-conducting member or the like is installed between the specimen holder shaft and the cooling section, the heat-conducting member can also be stably maintained at a high vacuum, thereby improving temperature stability.

[0088] Next, Figure 4 is a perspective view of the tip of a sample holder in one embodiment of the present invention. In Figure 4, 1 denotes a seal portion, 5 denotes an outer cylinder portion, 30 denotes an electrode, 31 denotes an electrode fixing screw, 32 denotes a biaxial tilt cam structure, 33 denotes a groove, and 34 denotes a tip. In the present invention, a tip or cartridge 34 can be used to mount the sample on the sample holder tip. The tip 34 can also be fixed using the electrode 30. The electrode 30 can also be fixed to the sample mounting stage using the electrode fixing screw 31. In this example, a biaxial tilt cam structure 32 can also be provided, and the sample can be tilted biaxially using the sample holder shaft, handle, etc. In addition, a groove 33 is cut from the side of the sample holder tip to the side of the sample holder shaft. Wiring can be fixed in this groove, and the wiring at the sample holder tip can be stored together with the sample holder tip. The groove 33 can be installed, for example, up to the current-carrying wire extension portion 4 in Figure 1. In other words, it is possible to fix the wiring from the tip of the sample holder to the retract (groove of the pull-out shaft) and store it together with the wiring. This can be achieved by drawing a vacuum up to the dewar.

[0089] Fig. 5 is a perspective view of the tip of the sample holder in one embodiment of the present invention. It is a diagram showing the state in which the tip of the sample holder is stored in one example. In Fig. 5, 1 indicates a seal portion and 5 indicates an outer cylindrical portion. Note that, although an O-ring is arranged at the tip in the figure, an O-ring may be embedded (arranged) inside the front of the outer cylindrical portion of the sample holder.

[0090] Figure 6 shows a side cross-sectional view of the tip of the sample holder in one embodiment of the present invention. In Figure 6, 1 denotes a seal, 40 denotes a MEMS chip, 41 denotes an electrode, 42 denotes a fixing portion (for fixing the voltage application portion), 43 denotes a sample stage, 44 denotes a camshaft, 45 denotes a sample holder shaft (for fixing the voltage application portion), 46 denotes an outer cylinder, 47 denotes a voltage application portion, and 48 denotes a sample. In this example, the voltage application portion (electrode) and the sample stage are integrated, so the tip of the sample holder can be stored in the outer cylinder along with the voltage application portion. The necessary structure can be used to store the sample holder in a minimum diameter of 7 mm.

[0091] Figure 7 is a top view of the tip of a sample holder in one embodiment of the present invention. In Figure 7, 1 denotes a seal portion, 40 denotes an MEMS chip, 41 denotes an electrode, 42 denotes a fixing portion (fixing of the voltage application portion), 43 denotes a sample stage, 44 denotes a camshaft, 46 denotes an outer cylinder portion, 47 denotes a voltage application portion, and 50 denotes an electrode terminal. In this example, a voltage application portion 47 is disposed on the sample stage 43, so that an electrode 41 from the voltage application portion 47 can be brought into contact with an electrode terminal 50 from the chip or cartridge 40 to conduct electricity. In this case, the electrode terminal 50 can be used to fix the chip or cartridge 40 to the sample stage 43, thereby fixing the sample to the sample stage 43.

[0092] Thus, in the present invention, the vacuum of the Dewer and the TEM can be made the same to achieve air non-exposure while cooling and energizing. Furthermore, by storing the tip from the electrode-equipped sample pedestal along with wiring that carries electricity to the retractable shaft, it is possible to realize a non-air-exposed cooling holder that can be cooled with liquid nitrogen. In other words, in the present invention, by making the vacuum of the Dewer and the TEM the same, the difference in the influence of radiant heat when cooling is eliminated, thereby preventing thermal drift due to cooling. Since there is no difference in the influence of radiant heat when controlling the temperature, more advanced temperature control is possible, and thermal expansion can be prevented at the nanometer level.

[0093] In this invention, by observing changes in a material caused by heating (directly below) a sample, applying an electric field, or passing an electric current in the vicinity of the sample using a transmission electron microscope, etc., it is possible to clarify the state of phase transformation, changes in atomic positions, and electrochemical behavior at the microscopic level. In addition, by spraying gas near the sample or flowing a fluid such as gas in a space separated from the vacuum, it is possible to perform electron microscope observations in almost real environments.

[0094] As described above, the specimen holder of the present invention locates the seal (and / or hermetic) closer to the handle, i.e., in a large open area, thereby dramatically simplifying design, wiring and assembly work, as well as maintenance.

[0095] Furthermore, by mirror-finishing the desired inner surface of the sample holder according to the condition of the vacuum exhaust system, the TEM's vacuum exhaust system can continue to pump air. This reduces the frequency of refrigerant refills due to deterioration in performance, significantly shortening the time until data acquisition for the sample. Therefore, the sample holder of the present invention can dramatically improve productivity in sample handling. Furthermore, the mirror-finished inner surface allows the heat transfer component to be stably maintained at a high vacuum, improving temperature stability. Thus, the sample holder of the present invention is expected to make a significant contribution to the development of various research fields.

[0096] The sample holder of the present invention is suitable for use under high vacuum conditions and is expected to be useful in a wide range of fields. The sample holder of the present invention enables highly accurate visualization, image formation, and analysis of samples under high vacuum conditions, and is expected to make a significant contribution to the development of research.

[0097] REFERENCE SIGNS LIST 1 Seal section 2 Sample holder shaft section (rotation shaft) 3 Current carrying wiring 4 Current carrying wiring expansion section 5 Outer cylinder section 6 Vacuum area, etc. 7 Support section 8 Cooling section (Dewar section) 9 Second seal section 10 Axis tilt motor 11 Handle section 20 Feed-through section 30 Electrode 31 Electrode fixing screw 32 Two-axis tilt cam structure 33 Groove 34 Tip 40 Tip 41 Electrode 42 Fixing section 43 Sample stage 44 Camshaft 45 Sample holder shaft (sample holder shaft section) 46 Outer cylinder section 47 Voltage application section 48 Sample 50 Electrode terminal 80 Electrode probe 81 Spring 82 Sample stage drive link 90 Sample stage 91 MEMS chip 92 Electrode probe 93 Sample stage drive link

Claims

1. A sample holder tip having a sample stage for mounting a sample and / or sample mesh, a fixing section for fixing the sample and / or sample mesh to the sample stage, and a voltage application section for applying a voltage to the sample, characterized in that the voltage application section is mounted on the sample stage.

2. The tip of the sample holder according to claim 1, wherein said voltage application section is integrated with said sample stage.

3. A sample holder tip as described in claim 1 or 2, characterized in that the sample and / or sample mesh is mounted on the sample stage via a chip or cartridge.

4. The tip of the sample holder according to claim 3, wherein said tip or cartridge has an electrode terminal.

5. A tip portion of a sample holder as described in any one of claims 1 to 4, further comprising a seal portion located toward the center of the electron microscope axis from the sample stage.

6. The tip of a sample holder according to any one of claims 1 to 5, further comprising an offset cam mechanism.

7. A sample holder having a sample holder tip according to any one of claims 1 to 6.

8. A sample holder comprising: a sample holder shaft having a sample holder tip as claimed in any one of claims 1 to 6; an outer cylinder capable of storing said sample holder shaft; a sample holder handle attached to said sample holder shaft on the opposite side to said sample holder tip; and a support part through which at least an electrode or a flow path passes, at a position further outward from the center than the position of the goniometer stage of said electron microscope when the sample holder is attached to an electron microscope.

9. The specimen holder according to claim 8, wherein said specimen holder shaft portion has a groove.

10. The sample holder according to claim 8 or 9, characterized in that the tip of the sample holder is retractable into the outer cylinder.

11. A specimen holder according to any one of claims 8 to 10, further comprising a cooling section capable of cooling the specimen holder shaft section.

12. A sample holder as described in any one of claims 8 to 11, characterized in that when the sample holder is installed in an electron microscope, a partition member is provided at a position further outward from the center than the position of the goniometer stage of the electron microscope, which separates the inside of the outer tube from the atmosphere.

13. The specimen holder according to claim 12, wherein said partition member is disposed at a connection between said outer cylinder portion and said specimen holder handle portion.

14. A sample holder according to any one of claims 8 to 13, characterized in that the sample holder shaft portion is rotatable about a sample holder axis.

15. The sample holder according to claim 14, wherein said rotation allows the sample to be rotated about the axis of said sample holder shank or about an axis perpendicular to the axial direction of said sample holder shank.

Images