JP2023058813A - stage - Google Patents

Abstract

To provide a stage capable of cooling or heating from the upper surface of a sample.SOLUTION: A stage according to the present invention includes a sample pedestal on which a sample is mounted, a heat insulating base installed under the sample pedestal, a heat conducting unit that is installed on the upper part of the sample pedestal and made of a member having heat conductivity, and a cooling unit or a heating unit. In a preferred embodiment of the stage of the present invention, the heat conducting unit made of a member having thermal conductivity is in contact with the cooling unit or the heating unit.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a stage, and more particularly to a stage capable of cooling or heating from the upper surface of a sample.

In recent years, high-resolution analysis in electron microscopes such as transmission electron microscopes (TEMs) and scanning transmission electron microscopes (STEMs) has progressed. There is a demand for resolution analysis. In recent years, "in situ observation", which involves cooling (or heating, applying an electric field, applying a magnetic field, or rotating) while observing a sample in an electron microscope, has been attracting attention. In particular, sample cooling is thought to be effective in reducing electron beam damage to the sample, and sample cooling has been tried from this point of view. For example, as an apparatus having a cooling means, a cooling stage for placing a sample in which water is sublimated in a sample chamber of a scanning electron microscope, and a cooling stage extending above the cooling stage to cool the sample under observation of the scanning electron microscope There is known a sample processing apparatus using a scanning electron microscope provided with a manipulator for cutting out the necessary components of (Patent Document 1).

JP-A-62-85840

While there is such a need for cooling, in the prior art including the above-mentioned Patent Document 1, the only method for fixing the sample on the existing cooling stage is to attach the sample to the upper surface of the sample pedestal, and the sample is cooled from the lower surface. It remains to do That is, in the conventional cooling stage, it was common to attach the sample to the sample pedestal using a double-sided tape or an adhesive for observation. There is no problem with the existing method in terms of observing the temperature change, and it is also a rational method in terms of the positional relationship of the detector. It changed from the lower surface to the upper surface, and the state of the change was observed.

Here, when observing a phenomenon that occurs due to temperature change such as phase transformation, the phenomenon observed on the upper surface may be that the transformation starts from the lower surface that is in thermal contact, and the process or result appears on the surface. is high, and it is important to observe the surface where cooling/heating starts in order to observe the 'initial stage' of material changes with temperature as a parameter. However, with the existing technology, it was difficult to capture the temperature change, which always occurs from the bottom surface. This point is a problem that can occur not only when the sample is cooled, but also when the sample is heated.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a stage capable of cooling or heating a sample from the upper surface thereof in order to solve the above problems.

In order to achieve the above object, the present inventor has found the present invention as a result of earnestly studying the mechanism of the stage.

That is, the stage of the present invention includes a sample pedestal on which a sample is mounted, a thermally insulating base installed below the sample pedestal, and a thermally conductive portion installed above the sample pedestal and made of a member having thermal conductivity. and a cooling unit or a heating unit.

Further, in a preferred aspect of the stage of the present invention, the heat conducting portion made of the member having heat conductivity is in contact with the cooling portion or the heating portion.

Moreover, in a preferred embodiment of the stage of the present invention, it is characterized by further comprising a thermoelectric element installed close to the cooling section or the heating section.

Also, in a preferred embodiment of the stage of the present invention, the heat conducting portion is extendable.

Further, in a preferred aspect of the stage of the present invention, the heat conducting portion has a gap for preventing interference with electron beams.

Further, in a preferred embodiment of the stage of the present invention, it is characterized by further comprising a sample pedestal retainer for pressing the sample pedestal.

Further, in a preferred embodiment of the stage of the present invention, it is characterized by having a heat conductive spacer having one or more holes between the sample and the sample pedestal retainer.

Further, in a preferred embodiment of the stage of the present invention, it is characterized by having a horizontal adjustment member between the sample pedestal and the thermal insulation base.

In a preferred embodiment of the stage of the present invention, the thermoelectric element is a thermoelectric element that utilizes at least one of the Peltier effect and the Thomson effect.

In a preferred embodiment of the stage of the present invention, the heat radiation side of the thermoelectric element is in contact with the cooling section, the heating section, or the heat conducting section.

Further, in a preferred embodiment of the stage of the present invention, the cooling section is made of at least one of solid refrigerant, liquid refrigerant, and gaseous refrigerant.

ADVANTAGE OF THE INVENTION According to the stage of this invention, there exists an advantageous effect that the stage which can be cooled or heated from the upper surface of a sample can be provided. Further, according to the stage of the present invention, there is an advantageous effect that it is possible to accurately observe the initial stage of the change in the material of the sample.

FIG. 1 shows a conceptual diagram of an example stage in one embodiment of the present invention. FIG. 1(a) is a side view of a stage in one embodiment of the present invention, FIG. 1(b) is a cross-sectional view of the stage taken along line A-A in FIG. 1(a), and FIG. The enlarged view of the B part of (b) is each shown. FIG. 2 shows one embodiment of a thermoelectric element applicable to the present invention. FIG. 2(a) shows a cross-sectional view of a Peltier element, and FIG. 2(b) shows a schematic diagram of the principle of the Peltier element. FIG. 3 shows a conceptual diagram of an example stage in one embodiment of the present invention. FIG. 3(a) shows a perspective view of a stage in one embodiment of the present invention, and FIG. 1(b) shows a top view of the stage.

The stage of the present invention includes a sample pedestal on which a sample is mounted, a thermally insulating base installed at the bottom of the sample pedestal, a heat conductive part installed at the top of the sample pedestal and made of a member having thermal conductivity, and a cooling part or a heating part. In the present invention, the sample stage on which the sample is mounted is not particularly limited in terms of shape, structure, etc., as long as the sample to be observed in the electron microscope can be mounted. In addition, in the present invention, the cooling section or heating section is not particularly limited, including its shape and structure, as long as it can cool or heat the sample to be observed in the electron microscope. In addition, in the present invention, from the viewpoint of performing experiments accurately by eliminating complicated temperature factors, a heat insulating base is installed under the sample pedestal. First, the case of cooling instead of heating will be described as an example. Normally, the sample is fixed (double-sided tape or adhesive) on the bottom surface and cooled from the bottom surface. In addition, since electron beams are applied from above and electron microscopes are basically used for observation in a vacuum, the upper surface is almost perfectly thermally insulated (vacuum). Although the temperature gradient is generated from the lower surface to the upper surface, the temperature is uniformly cooled after a certain period of time. This process is sufficient if you want to know the change in the material of the sample as a whole. Next, when cooling from the upper surface, the upper surface can also be cooled by, for example, sandwiching it between the upper surface and the lower surface. However, it is also cooled from the lower surface. In this case, the effect of cooling from the upper surface and the effect of cooling from the lower surface are mixed. The temperature gradient is small and the sample can be fixed firmly, but on the other hand, if you want to know the change in the top surface (observation surface), it is difficult to determine whether the change was caused by cooling or the bottom surface. Now, let us consider the case where the lower surface is not thermally insulated even if it is not cooled. In this case, an inflow of heat occurs from the lower surface. Then, it can be considered that the upper surface is cooled and the lower surface is heated at the same time. Since there is an influx of heat from the bottom surface, not only does it affect the temperature of the top surface, but when looking at the entire sample, there is always a temperature gradient and the temperature is not uniform. Gone. Furthermore, when the lower surface is thermally insulated, it can be considered that the phenomenon is reversed from cooling from the lower surface. Therefore, the interpretation becomes easier in understanding the phenomenon that occurred. The need to thermally insulate the lower surface is as described above. In the present invention, the thermally insulating base installed under the sample pedestal enables the thermal insulation of the lower surface. Although the case of cooling has been described above as an example, the necessity of thermally insulating the lower surface is the same in the case of heating as well.

Further, in the present invention, a heat conducting portion is provided on the upper portion of the sample pedestal and made of a member having heat conductivity. As a result, the sample can be cooled or heated from above, and the surface from which observation is started is the upper surface of the sample. Therefore, it is possible to observe from the surface where cooling or heating is started, which could not be realized in the past. Therefore, it is possible to accurately observe initial changes in the material.

In the present invention, the member having thermal conductivity that can be used for the thermally conductive portion is not particularly limited, but examples thereof include copper and copper alloys, aluminum and aluminum alloys, silver, gold, and tungsten. .

Further, in a preferred aspect of the stage of the present invention, the heat conducting portion made of the member having heat conductivity is in contact with the cooling portion or the heating portion. In the present invention, it is possible to cool or heat the sample from above by contacting the heat-conducting portion provided on the upper portion of the sample pedestal with the cooling portion or the heating portion.

Moreover, in the present invention, the sample can be cooled and heated, and the following advantages are obtained when the cooling section is used. That is, by cooling the sample via a heat conductive portion made of a member having thermal conductivity in the vicinity of the upper surface of the sample, the cooled heat conductive portion can have a cold trap function for preventing contamination.

Here, when the expression "cold trap" is used, it can be understood as a device that cools and captures a minute amount of suspended matter (gas: hydrocarbons, etc.) in a vacuum. That is, if there is gas in the vacuum, it is expected that the gas will hit the sample together with the irradiation of the electron beam and deposit on the sample. As in the present invention, when a cooling member is arranged near the upper surface, the vicinity of the sample is surrounded by a cooled metal member (cooling member) within a range that does not block electron beam irradiation, etc., creating a locally high vacuum area. mechanism can be realized. This makes it possible to construct a cooling and condensing mechanism in order to collect the emitted gas, which in turn makes it possible to prevent the gas present in the vacuum from adhering to the sample inside the electron microscope.

Further, in a preferred embodiment of the stage of the present invention, the cooling section is made of at least one of solid refrigerant, liquid refrigerant, and gaseous refrigerant. In the cooling section, the coolant can be appropriately set depending on the application, and is not particularly limited. From the viewpoint of versatility, a liquid can be mentioned as a preferable medium. If it is a liquid (such as water), the temperature can be adjusted using a general-purpose device (cooling chiller), but since it is a fluid, it can be a source of vibration. It is also possible to use liquid nitrogen or liquid helium as the liquid.

In addition, in the present invention, the cooling unit may be a solid refrigerant from the viewpoint that the influence of vibration due to water flow or pulsating flow can be reduced to zero as compared to water cooling. That is, in the present invention, it is possible to cool the heat radiating surface of the Peltier device or the like with a solid refrigerant such as dry ice. As a result, compared to water cooling, it is possible to eliminate the influence of vibrations caused by water currents and pulsating currents as much as possible. In addition, in the case of a solid, it is possible to control the temperature of the cooling part by using a thermoelectric element as will be described later.

On the other hand, even when the cooling gas is flowed at a very small flow rate, it can be used in the present invention because the effect of vibration is small. As the cooling gas, for example, liquid nitrogen can be gasified and taken out. This allows good cooling of the sample. In the present invention, the cooling gas is not limited to liquid nitrogen. If the gas is only weakly passed through the heat dissipation surface, it is considered that there is almost no effect of vibration and it is practical. Therefore, in the present invention, as described above, even when a solid refrigerant is actually used as the cooling part, it is sufficient to apply cold air with a gap instead of pressing it against the heat dissipation surface. Furthermore, when liquid nitrogen gas is used, observation is possible without being affected by vibration by passing the cooling gas through the heat radiation surface. Regarding the difficulty in adjusting the temperature of the cooling section, it is possible to control it using a thermoelectric element as described later.

Also, in a preferred embodiment of the stage of the present invention, the heat conducting portion is extendable. That is, an extensible heat-conducting portion is provided by extending laterally from the cooling portion or heating portion, the sample is placed on the separately prepared heat-insulating portion, and the heat-conducting portion is extended to the top of the sample. can be cooled or heated. That is, a sample pedestal having a structure thermally insulated from the outside can be prepared outside the stage, and then the heat conducting portion can be extended to the sky above the sample pedestal. Then, the sample can be sandwiched between the heat conducting portion and the sample pedestal. Such a structure can also be a preferred aspect of the present invention. In the drawings to be described later, the structure is such that they are stacked on the stage for space saving, but it is also possible to extend the heat conduction path to a place away from the stage. Note that the extensible heat-conducting portion may have any shape, such as an arm shape, a clamp shape, or the like. In the present invention, the extensible heat-conducting part can be made of a member having heat conductivity as described above. The shape, structure, etc. are not particularly limited as long as the cold heat source can be propagated to the sample.

Moreover, in a preferred embodiment of the stage of the present invention, it is characterized by further comprising a thermoelectric element installed close to the cooling section or the heating section. As noted above, in embodiments that provide an extensible heat-conducting portion, it is possible to place a thermoelectric element on top of the heat-conducting portion. In the present invention, the arrangement position of the thermoelectric element is not particularly limited as long as it is installed close to the cooling section or the heating section. A thermoelectric element makes it possible to set the required temperature of the sample in an efficient manner, ie to control the temperature. In addition, in the embodiment using a thermoelectric element, the cooling/heating response is good and the influence of thermal drift can be suppressed as much as possible, and the cooling/heating response is improved, so precise temperature control is possible. . In addition, in a mode using a thermoelectric element, cooling and heating can be realized with a single element simply by reversing the direction of current flow. Easy. In addition, since precise temperature control is possible by adjusting the output of the input electric power, precise temperature control is possible and the influence of thermal drift can be suppressed as much as possible.

Further, in a preferred aspect of the stage of the present invention, the heat conducting portion has a gap for preventing interference with electron beams. In the present invention, since the heat-conducting part is installed above the sample, if the heat-conducting part exists at the position where the electron beam is irradiated, the member will interfere with the electron beam. . The heat-conducting portion can be curved so as not to interfere with the electron beam, but the interference can be prevented by providing a gap. For example, a circular hole can be arranged in the heat conducting path on the upper surface of the sample so as not to interfere with the electron beam. The air gap does not necessarily have to be circular, and may be square and press the sample from both sides or multiple directions with a plate. However, from the viewpoint of isotropic heat conduction to the sample, a circular air gap is preferable. .

In a preferred embodiment of the stage of the present invention, the heat radiation side of the thermoelectric element is in contact with the cooling section, the heating section, or the heat conducting section. That is, in the present invention, the thermoelectric element may be placed in the vicinity of the cooling part, the heating part, or the heat conducting part. may be pressed against the heat radiating side (heat radiating surface side), or may have a structure in which a gap is provided and cold air is applied. When applying cool air, either natural convection or forced convection using a fan or the like may be used. However, if forced convection causes vibration, natural convection is preferable depending on the degree of forced convection. Even in the case of natural convection, since the solid refrigerant has a sufficiently low temperature, there is a large temperature gradient between the heat radiation surface side and the cold air in the cooling part such as the solid refrigerant, so sufficient heat transfer occurs. Therefore, it is considered that the heat radiation surface can be cooled appropriately. Forced convection is more effective than natural convection, and water cooling is more effective than air cooling.

In a preferred embodiment of the stage of the present invention, the thermoelectric element is a thermoelectric element that utilizes at least one of the Peltier effect and the Thomson effect. The Peltier effect (also known as the Peltier effect) is the effect of converting electrical energy into thermal energy. When two dissimilar metals (or semiconductors) are connected to each other and an electric current is applied, a temperature difference occurs between the two ends. . Especially called a Peltier element, it is used for cooling precision instruments and wine cellars. In addition, the Thomson effect is the effect of generating heat other than Joule heat (heat absorption when reversing the current) that occurs when an electric current is passed through a uniform metal (or dissimilar metal) with a temperature gradient. Say things. Both can generate heat or absorb heat.

From the viewpoint of efficient heat dissipation from the thermoelectric elements, a heat radiating member may be installed between the thermoelectric elements and the cooling section, the heating section, or the heat conducting section.

Further, in a preferred embodiment of the stage of the present invention, the thermoelectric element is a Peltier element from the viewpoint of having good cooling/heating response and suppressing the influence of thermal drift as much as possible. A Peltier element is also called a Peltier element (thermo module), which is a general term for elements utilizing the Peltier effect. The currently mainstream structure, which is said to have the best performance, is called the "π-type", and has the structure shown in FIG. By passing a current through a PN junction using a P-type semiconductor and an N-type semiconductor, it is possible to cause heat dissipation between P-N and heat absorption between N-P.

The principle is as follows. FIG. 2 shows one embodiment of a thermoelectric element applicable to the present invention. FIG. 2(a) shows a cross-sectional view of a Peltier element, and FIG. 2(b) shows a schematic diagram of the principle of the Peltier element. In FIG. 2(a), 21 is a hot side metal (mainly Cu), 22 is a ceramic substrate (mainly alumina), 23 is a heat dissipation surface, 24 is an N-type semiconductor, 25 is a P-type semiconductor, 26 is an electric wire, 27 is the power source, 28 is the heat absorption, 29 is the conduction band of the N-type semiconductor, 30 is the heat dissipation, 31 is the plus side, 32 is the heat absorption side, 33 is the valence band, 34 is the heat dissipation side, 35 is the minus side, and 36 is cold. Side metal (mainly Cu), cold side metal (mainly Cu) 37, electrons 38, holes 39, and conduction band 40 of the P-type semiconductor.

In FIG. 2A, the minus electrode is connected to the metal 36 on the N-type semiconductor 24 side. Therefore, electrons are pushed up from the conduction band of this metal 36 to the conduction band 29 of the N-type semiconductor 24 by the voltage. At this time, since there is an energy gap between the conduction band of the metal 36 and the conduction band 29 of the N-type semiconductor 24 , the electrons take heat energy from the metal 36 and as a result cool the metal 36 . Electrons subsequently flow and fall from the conduction band 29 of the N-type semiconductor 24 into the conduction band of the metal 21 . The electrons release thermal energy due to the energy gap between both bands. The hot side metal 21 is thus heated. Further, the electrons that have flowed fall from the conduction band of the metal 21 into the holes 39 that have flowed through the P-type semiconductor 25 and release thermal energy to heat the metal 21 on the hot side. In the P-type semiconductor 25 , holes 39 are produced by voltage and flow from the cold side 37 to the hot side 21 . The electrons generated at that time are pushed up to the conduction band of the metal on the cold side by the voltage, deprive the heat energy corresponding to the energy gap between them, and cool the metal 37 on the cold side. This flow of current transfers heat from the cold side to the hot side of the Peltier module. In addition to heat energy carried by electric current, there is heat energy carried by heat conduction, but the heat energy carried by heat conduction flows in the opposite direction. In other words, the Peltier module will exhibit good performance if the heat energy on the hot side is removed as quickly as possible with a heat sink or the like. Simply put, electrons carry (take away) heat.

The material of the semiconductor is not particularly limited, and any of them can be applied.

Regarding the performance of the Peltier, generally speaking, the performance of the Peltier can be considered by how much temperature difference ΔT can be created with respect to the temperature Th when the temperature on the heat radiation side is kept constant. For example, ΔT=93, 85, 75 for Th=75, 50, 25 (°C). If the heat-dissipating surface is simply cooled to the temperature of liquid nitrogen (-196°C), the temperature of the heat-absorbing surface will exceed -200°C. It is assumed that ΔT=10°C. The lower the temperature, the less heat is needed to excite electrons, so the Peltier cooling ability decreases. This is probably because the cooling capacity as a whole decreases as a result of heat generation.

Further, in a preferred embodiment of the present invention, in the case of cooling, it is possible to set the temperature to a lower temperature by cooling the heat radiation side of the thermoelectric element, and in the case of heating, the thermoelectric From the viewpoint that heating can be performed while reducing the load by warming the heat radiation side of the element, the heat radiation side of the thermoelectric element is in contact with the cooling part, the heating part, or the heat conducting part. characterized by In the following examples, the case of cooling is mainly described, but in the present invention, it is also possible to heat with a thermoelectric element. Since the lower surface of the thermoelectric element cools down during heating, it is necessary to warm the heating part before use (treat at a higher temperature than the lower surface). In this case, it can act as a heating section instead of a cooling section.

In the case of heating, the phenomenon is simply reversed compared to the case of cooling, but the practicality also changes depending on the shape of the thermoelectric element such as a Peltier element (whether it is a multistage type or not). Basically, when aiming at an infinitely low temperature, a multi-stage thermoelectric element such as a Peltier element can be used. In this case, it is possible to form a pyramid-like structure in which the area of the heat absorption surface (upper stage) is small and the area becomes large toward the heat dissipation surface. The reason for such a structure is that, basically, the larger the area, the larger the amount of heat absorption, so that the heat absorbed by the upper element with a small area is discharged by the lower element with a larger area. When the polarity of the current is reversed for the purpose of heating, it is not simple, and the heat from the lower stage, which has a large area, tends to flow into the upper stage, which has a small area, at once. If the upper stage cannot absorb the heat, the heat accumulates in the middle stage and tends to be higher than the upper stage. For this reason, many Peltier elements are considered to be around +100°C (the temperature at which the solder at the junction does not deteriorate) even if they are used on the heating side. In principle, the temperature of the Peltier element can be precisely controlled from near room temperature to the minus range by creating a heat absorption surface and a heat dissipation surface by the movement of electrons and controlling the amount of current flowing through the Peltier element. These effects enable stable high-resolution observation.

Further, in a preferred embodiment of the stage of the present invention, from the viewpoint of firmly fixing the sample to suppress vibration and thermal drift, and from the viewpoint of ensuring sufficient thermal contact, a sample pedestal for pressing the sample pedestal is added. It is characterized by having a presser foot. If it is necessary to fix the sample on the lower surface, the height must be adjusted each time depending on the thickness of the sample. For example, the sample pedestal retainer can adopt a ring screw type so as to support various sample thicknesses. The sample pedestal retainer does not necessarily have to be a screw, and may be a plate spring, coil spring, clamp mechanism, or the like. The sample pedestal retainer is preferably of a screw type because it is possible to adjust the clamping pressure and sufficiently ensure thermal contact. The material for holding the sample pedestal, such as a ring screw, can be a material with high thermal conductivity, such as gold, silver, copper, aluminum, copper, or alloys thereof. Moreover, the material of the sample pedestal retainer is preferably a material different from that of the heat conduction path in order to avoid galling due to the alloy.

Further, in a preferred embodiment of the stage of the present invention, since a temperature gradient is generated from the heat conducting portion toward the center of the specimen, from the viewpoint of uniformly cooling and heating the observation area, Second, it has a thermally conductive spacer with one or more holes. For example, when a ring screw is used to hold the sample pedestal, a temperature gradient is created from the vicinity of the ring screw toward the center of the sample. It may be preferred to stretch over the sample. For example, a heat-conducting spacer with a plurality of holes can be arranged between a sample pedestal retainer such as a ring screw and the sample. Although the observable visual field range is reduced, the temperature gradient between the vicinity of the outer edge and the vicinity of the center of the hole can be reduced. In addition, in the case of electropolished samples, etc., there is a gentle depression from the outer edge to the center, and it is thought that thermal contact with the sample pedestal holder, such as a ring screw, is difficult. A relatively soft metal foil such as indium (which can have holes) may be inserted between the electrodes.

Further, in a preferred embodiment of the stage of the present invention, from the viewpoint of improving thermal contact, it is characterized by having a horizontal adjustment member between the sample pedestal and the thermal insulation base. Ideally, the top and bottom surfaces of the sample are parallel after the sample for SEM has been polished, but in reality they are slightly not parallel. Similarly, there is no guarantee that the sample pedestal portion on the stage side and the sample pedestal holder such as a ring screw are parallel. Since it is necessary to fix the sample to the sample pedestal, if the respective members and the sample are not parallel, there is a risk that a gap will be formed and the thermal contact will be insufficient and the heat will not be transmitted. Therefore, by inserting a horizontal adjustment member directly under the sample pedestal, it is possible to create a mechanism in which the upper surface of the sample becomes parallel to the sample pedestal holder in accordance with the force with which the sample pedestal holder such as a ring screw presses the sample. In the present invention, the horizontal adjustment member is not particularly limited, but for example, one ball or a spring may be arranged in the center, or a plurality of them may be arranged in a well-balanced manner. The horizontal adjusting member such as a ball can have the effect of thermally insulating the sample pedestal and the bridge (thermal insulating base).

The stages of one embodiment of the present invention will be described below with reference to the drawings, but the present invention is not intended to be limited to these.

FIG. 1 shows a conceptual diagram of an example stage in one embodiment of the present invention. FIG. 1(a) is a side view of a stage in one embodiment of the present invention, FIG. 1(b) is a cross-sectional view of the stage taken along line A-A in FIG. 1(a), and FIG. The enlarged view of the B part of (b) is each shown. In FIG. 1, 1 is a heat insulating base, 2 is a heat conducting part, 3 is a cooling or heating connection part, 4 is a thermoelectric element (if a thermoelectric element is required), 5 is a cooling part or a heating part (or a cooling part) 6 is a heat radiating member, 7 is a sample, 8 is a sample base, 9 is a heat conductive spacer, 10 is a bridge, 11 is a horizontal adjustment member, 12 and 50 are sample holders ring screw), respectively.

With reference to the drawings, the role of each member, the connection between each member, etc. of the stage in one embodiment of the present invention will be described below. First, there is a stage main body, and although FIG. 1 shows an embodiment having a thermoelectric element 4, the thermoelectric element 4 may or may not be present. If there is no thermoelectric element 4, the part 4 can have a cooling part, a heating part, a heat conducting part, or the like. In this example, since the thermoelectric element 4 is used, a heat radiation member (heat radiation processing member) 6 may be provided as shown in the figure, if necessary. In this example, the heat source (cooling or heating) from the cooling part or heating part (or the connection part with the cooling part or heating part) 5 includes the heat dissipation member 6, the cooling or heating connection part 3, the thermoelectric element 4, the heat It is designed to reach the upper part of the sample via the conducting part 2 . The heat source (cooling or heating) is applied to the sample 7 via the heat conducting part 2, the ring screw 12 (in the case of the mode using the sample pedestal holder), or the heat conducting spacer 9 (in the case of the mode using the heat conducting spacer). can be transmitted to In this aspect, the horizontal adjustment member uses a ball. If the upper surface member and the lower surface member are not parallel to the sample surface, there is a risk that proper thermal contact cannot be made. Therefore, in this example, a mechanism is adopted in which the upper surface of the sample becomes parallel to the ring screw according to the force with which the ring screw presses the sample by inserting a ball directly under the sample pedestal. At the same time, the ball can have the effect of thermally insulating the sample pedestal and the bridge. In this example, the ball is used, but one spring or a plurality of springs may be arranged in a well-balanced manner.

FIG. 3 shows a conceptual diagram of an example stage in one embodiment of the present invention. FIG. 3(a) shows a perspective view of a stage in one embodiment of the present invention, and FIG. 1(b) shows a top view of the stage. In FIG. 3, 51 denotes a heat conductive spacer, 52 denotes a gap provided in the heat conductive portion, and 53 denotes a fixture for fixing the heat insulating base.

Thus, the stage of the present invention can be suitably used in scanning electron microscopes, and can provide a mechanism capable of cooling and heating the specimen from above. That is, according to the present invention, it is possible to satisfactorily control the specimen fixing method and the direction of heat conduction when the specimen is cooled or heated within a scanning electron microscope (SEM). This may allow observation of the early stages of phenomena (such as phase transformations) caused by temperature changes. In addition, in the case of cooling, it was found that the presence of a cooling member near the observation surface acts as a cold trap and contributes to the reduction of contamination.

In the above aspect, a heat conduction path (heat conduction portion) is detoured from the cooling/heating source to the upper surface of the sample in an arm shape, and a mechanism is devised to thermally insulate the sample pedestal portion so that cooling and heating can be performed from the upper surface. However, the heat transfer paths do not necessarily have to be detoured as shown, and may extend laterally from the cooling surface. On the other hand, the lower surface of the sample must be thermally insulated, and this example is an example in which the cooling surface is bridged (thermally insulating base) and fixed to the frame, but there is no particular limitation. Also, for the bridge (thermal insulation base), a material having low thermal conductivity such as resin or titanium can be preferably used.

By heating or cooling the sample from above, it is possible to observe the sample in situ, which is applicable in a wide range of technical fields.

1 Thermal insulation base
2 heat conduction part 3 cooling or heating connection part 4 thermoelectric element (if thermoelectric element is required)
5 Cooling part or heating part (or connecting part with cooling part or heating part)
6 Heat dissipation member 7 Sample 8 Sample pedestal 9 Thermal conduction spacer 10 Bridge 11 Horizontal adjustment member 12, 50 Sample retainer (in this case, ring screw)
21 Hot side metals (mainly Cu)
22 Ceramic substrate (mainly alumina)
23 Heat dissipation surface 24 N-type semiconductor 25 P-type semiconductor 26 Electric wire 27 Power supply 28 Heat absorption 29 N-type semiconductor conduction band 30 Heat dissipation 31 Plus side 32 Heat absorption side 33 Valence band 34 Heat dissipation side 35 Minus side 36 Cold side metal (mainly Cu)
37 cold side metals (mainly Cu)
38 Electron 39 Hole 40 Conduction band of P-type semiconductor 51 Thermally conductive spacer 52 Air gap 53 provided in the thermally conductive part Fixture for fixing the thermally insulating base

Claims (11)

A sample pedestal on which a sample is mounted, a thermally insulating base installed at the bottom of the sample pedestal, a heat conducting section installed at the top of the sample pedestal and made of a member having thermal conductivity, and a cooling section or heating section. , a stage having . 2. The stage according to claim 1, wherein the heat conducting portion made of a member having heat conductivity is in contact with the cooling portion or the heating portion. 3. The stage according to claim 1, further comprising a thermoelectric element installed close to said cooling part or said heating part. 4. The stage according to any one of claims 1 to 3, characterized in that said heat conducting part is extendable. 5. The stage according to any one of claims 1 to 4, wherein the heat conducting portion has a gap for preventing interference with electron beams. 6. The stage according to any one of claims 1 to 5, further comprising a sample pedestal retainer for pressing said sample pedestal. 7. The stage according to claim 6, further comprising a heat-conducting spacer having one or more holes between said sample and said sample pedestal retainer. The stage according to any one of claims 1 to 7, further comprising a horizontal adjustment member between the sample pedestal and the thermal insulation base. 9. The stage according to any one of claims 3 to 8, wherein the thermoelectric element is a thermoelectric element that utilizes at least one of Peltier effect and Thomson effect. 9. The stage according to any one of claims 3 to 8, wherein the heat radiation side of the thermoelectric element is in contact with the cooling section, the heating section, or the heat conducting section. 11. The stage according to any one of claims 1 to 10, wherein the cooling part is made of at least one of solid refrigerant, liquid refrigerant, and gaseous refrigerant.

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