Sample in-situ heating device and scanning electron microscope

Abstract

The invention provides a sample in-situ heating device and a scanning electron microscop.The sample in-situ heating device comprises a base; the heating piece is mounted on the base and is used for heating a sample; the cooling piece is used for cooling the base; the placement plate is positioned above the heating piece and is used for placing samples; the reflecting piece is located on the lower portion of the heating piece and used for reflecting heat of the heating piece towards one side of the storage plate. The heating part is located on the upper portion of the base, the reflecting part is arranged on the lower portion of the heating part, heat emitted by the heating part is reflected through the reflecting part, so that heat transmitted to the lower portion of the base is reduced, meanwhile, the base is cooled through the cooling part, and temperature rise of the base is relatively not obvious through combination of the reflecting part and the cooling part. And heat radiation from the base to the inner wall of the scanning electron microscope is reduced. The heat is reflected through the reflecting part, so that the temperature of the storage plate rises quickly, and the whole storage plate is heated uniformly, so that the temperature rise of the sample is uniform, and the temperature rise response is quick.

Description

Technical Field

[0001] The invention relates to the technical field of scanning electron microscopes, and in particular to a sample in-situ heating device and a scanning electron microscope. Background Art

[0002] With the deepening of scientific research, the observation of the in-situ dynamic behavior of materials and nanostructures has become increasingly important. Traditional electron microscopes can only provide static images. The existing heating platform directly installs the heating element in the heating platform, places the sample on the heating platform, and then heats the sample. This heating method of the sample causes the temperature of the heating platform to rise significantly. When the temperature of the heating platform is too high, it will affect the accessories in the scanning electron microscope cavity, making the imaging results of the scanning electron microscope inaccurate; the heating platform heats the sample through thermal radiation. This heating method makes the temperature of the sample near the heating element relatively high, resulting in uneven heating of the sample and low heating efficiency. Summary of the invention

[0003] In view of the above-mentioned shortcomings of the prior art, the object of the present invention is to provide a sample in-situ heating device and a scanning electron microscope, which are used to solve the problems in the prior art that the heat radiation generated after the heating platform is heated will affect the accessories in the scanning electron microscope cavity, the sample is heated unevenly, and the temperature rise response efficiency is low.

[0004] To achieve the above objectives and other related objectives, the present invention provides a sample in-situ heating device, comprising:

[0005] Pedestal;

[0006] A heating element, which is mounted on the base and is used to heat the sample;

[0007] A cooling element, used to cool the base;

[0008] A placement plate, the placement plate is located on the upper part of the heating element, and the placement plate is used to shield the light emitted by the heating element and place samples;

[0009] A reflector is located at the lower part of the heating element and is used to reflect the heat of the heating element toward one side of the storage plate.

[0010] Furthermore, the cooling member is a cooling channel arranged in the base, and both ends of the cooling channel are respectively provided with an inlet and an outlet connected to a cooling device.

[0011] Furthermore, the cooling channel includes a first channel, a second channel and a third channel, the first channel and the second channel are both connected to the third channel, the third channel extends from one side of the base to the other side, one end of the third channel is located in the base, and the other end is sealed.

[0012] Furthermore, a cavity is provided in the base, and the heating element and the reflecting element are both located in the cavity.

[0013] Furthermore, a boss is provided on the base, grooves are provided on both sides of the boss, and two ends of the heating element are respectively located in the grooves.

[0014] Furthermore, two sides of the heating element are connected to the base via first connecting columns, the first connecting columns are provided with through holes, and the heating element passes through the through holes.

[0015] Furthermore, both ends of the heating element are connected to the base via a first connecting column, the first connecting column is provided with a through hole, and the heating element passes through the through hole.

[0016] Furthermore, a base is provided at the bottom of the base, and a pin is provided on a side of the base away from the base.

[0017] On the other hand, the present application also provides a scanning electron microscope, comprising an electron microscope body and the above-mentioned sample in-situ heating device, the electron microscope body is equipped with an adapter flange, the adapter flange is equipped with a first interface, a second interface and a third interface, the first interface is used for the wire of the temperature measuring meter to pass through, the second interface is used for the wire of the heating element to pass through, and the third interface is provided with a pipeline connected to the cooling element.

[0018] Furthermore, an electron beam generating gun is arranged in the electron microscope body, and a thermal electron filter grid is installed at the front end of the pole shoe of the electron beam generating gun. The thermal electron filter grid is connected to a power line to generate a bias voltage. The thermal electron filter grid is used to eliminate thermal electrons emitted by the sample at high temperature under the action of the bias voltage.

[0019] As described above, the sample in-situ heating device provided by the present invention has the following beneficial effects: the heating element is located at the upper part of the base, and a reflector is arranged at the lower part of the heating element, and the heat emitted by the heating element is reflected by the reflector, so that the heat transferred to the lower part of the base is reduced, and at the same time, the base is cooled by the cooling element, and the combination of the two makes the temperature rise of the base relatively unobvious, reducing the heat radiation of the base to the inner wall of the scanning electron microscope. Reflecting heat by the reflector also makes the temperature of the placement plate rise faster and the entire placement plate is heated more evenly, so that the sample temperature rises more evenly and the temperature rise response is fast. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A schematic diagram of the structure of the sample in-situ heating device provided by the present invention;

[0021] Figure 2 for Figure 1 Schematic diagram of the structure without the storage plate;

[0022] Figure 3 for Figure 1 The main view of

[0023] Figure 4 for Figure 3 Section view along AA;

[0024] Figure 5 A schematic diagram of the structure of a scanning electron microscope provided by the present invention;

[0025] Figure 6 It is a schematic diagram of the structure of the hot electron filter grid;

[0026] Figure 7 It is a structural schematic diagram of the adapter flange;

[0027] Figure 8 This is a cross-sectional view of the third flange.

[0028] Part Number Description

[0029] 100-sample in-situ heating device, 101-base, 102-heating element, 103-placement plate, 104-cooling channel, 105-reflector, 106-inlet, 107-outlet, 108-first channel, 109-second channel, 110-third channel, 111-cavity, 112-boss, 113-groove, 114-first connecting column, 115-second connecting column, 116-ceramic gasket, 117-perforation, 118-base, 119-pin, 200-scanning electron microscope body, 201-adapter flange, 202-first interface, 203-second interface, 204-third interface, 205-electron beam generating gun, 206-thermal electron filtering grid, 207-first flange, 208-second flange, 209-third flange. DETAILED DESCRIPTION

[0030] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0031] It should be noted that the diagram provided in the present embodiment only illustrates the basic concept of the present invention in a schematic manner, so the diagram only shows the components related to the present invention rather than drawing according to the number, shape and size of the components during actual implementation. The type, quantity and ratio of each component during actual implementation can be a random change, and the component layout type may also be more complicated. The structure, ratio, size, etc. illustrated in the drawings of the present specification are only used to match the content disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions that the present invention can implement, so they have no technical substantive significance. Any modification of the structure, change of the proportional relationship or adjustment of the size should still fall within the scope of the technical content disclosed by the present invention without affecting the effect that the present invention can produce and the purpose that can be achieved. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of narration, and are not used to limit the scope of the present invention. The change or adjustment of its relative relationship should also be regarded as the scope of the present invention without substantially changing the technical content.

[0032] See also Figures 1 to 4 The present invention provides a sample in-situ heating device 100, including a base 101, a base 118 is arranged at the bottom of the base 101, and the base 118 mounts the base 101 on the high-precision displacement stage of the scanning electron microscope. The base 118 can be heat-insulated. Two pins 119 are arranged at the bottom of the base 118, which can match the elastic sockets on the high-precision displacement stage. At the same time, the base 118 is grounded to ensure insulation during the subsequent heating process and protect the scanning electron microscope. The number and orientation of the pins 119 are determined according to the elastic sockets on the high-precision displacement stage. The base 101 is generally made of oxygen-free copper, which meets the high thermal conductivity and has a low degassing rate under vacuum conditions, thereby reducing the impact on the subsequent imaging quality.

[0033] A heating element 102 is installed on the base 101, and the heating element 102 is used to heat the sample. The heating element 102 can be a heating wire or other heating element. The present application fixes the heating element 102 on the base 101 through two first connecting posts 114. The first connecting posts 114 and the base 101 are insulated by a T-shaped ceramic gasket 116. The heating element 102 is generally made of refractory, corrosion-resistant and oxidation-resistant metal.

[0034] The first connecting column 114 may be a bolt column. In order to fix the heating element 102 , a through hole 117 is provided on the first connecting column 114 . Both ends of the heating element 102 directly pass through the through hole 117 , and the heating element 102 is supported by the first connecting column 114 .

[0035] T-shaped ceramic gaskets 116 are provided on both sides of the first connecting column 114. The small diameter section of the T-shaped ceramic gasket 116 enters the hole of the base 101. The T-shaped ceramic gasket 116 insulates the first connecting column 114 from the base 101. The lower part of the base 101 fixes the first connecting column 114 through a locking nut.

[0036] In order to achieve more accurate temperature control of the heating element 102, a temperature meter is installed at the heating element 102. The temperature meter preferably uses a thermocouple, and both ends of the thermocouple are fixed to the base 101 through a second connecting column 115. The connection between the second connecting column 115 and the base 101 is the same as the first connecting column 114, and both use a T-shaped ceramic gasket 116 to insulate the base 101.

[0037] The heating element 102 will generate heat when in use, and the temperature of the base 101 will increase under the action of thermal radiation. After the temperature of the base 101 increases, the base 101 will also generate thermal radiation to affect the accessories in the scanning electron microscope. Therefore, in order to prevent the temperature of the base 101 from rising too much, the present application designs a cooling element, and the cooling element is used to cool the base 101. The cooling element directly cools the base 101 to prevent the temperature of the base 101 from rising too quickly, while also ensuring that it does not affect the heating of the sample.

[0038] The cooling element can be arranged inside the base 101 or outside the base 101. In order to reduce the volume of the sample in-situ heating device 100, the present embodiment directly arranges a cooling channel 104 inside the base 101, which is equivalent to flowing a cooling medium in the middle of the base, so that both the inner wall and the outer wall of the base 101 can be cooled. An inlet 106 and an outlet 107 are arranged at both ends of the cooling channel 104, which are connected to the cooling device through the inlet 106 and the outlet 107 to realize the circulation of the cooling medium.

[0039] For the convenience of processing and connection, the inlet 106 and the outlet 107 are arranged on the side where the first connecting column 114 is installed, so that all the wires and tubes can be in one direction. In order to prevent the first connecting column 114 from interfering with the inlet 106 and the outlet 107, an extended edge is designed on the side of the base 101, and the overall structural design of the base 101 is a "7" shape when viewed from the side. The inlet 106 and the outlet 107 are both designed as stepped holes.

[0040] The inlet 106 is connected to the first channel 108, and the outlet 107 is connected to the second channel 109. The first channel 108 and the second channel 109 can be arranged in parallel or not. A third channel 110 is also arranged in the base 101. The first channel 108 and the second channel 109 are both connected to the third channel 110. A plurality of parallel third channels 110 can be arranged in the base 101, which is equivalent to the third channel 110 bending back and forth in the base 101. This can extend the path of the cooling channel and make the cooling effect better, but it will increase the processing difficulty. The third channel 110 extends inward from one side of the base 101. After being connected to the first channel 108 and the second channel 109, the cooling channel 104 forms a U shape. Alternatively, multiple first channels 108, multiple second channels 109 and multiple third channels 110 are directly arranged, and the structure after formation is multiple U-shaped overlaps. Multiple first channels 108, multiple second channels 109 and multiple third channels 110 can be arranged in the same plane or up and down along the height of the base.

[0041] In order to prevent the cooling medium from flowing out, the third channel 110 is a blind hole, so that only one end is located outside the base 101, and the outside of the third channel 110 is sealed by vacuum brazing. Alternatively, the third channel 110 is designed as a through hole, and both ends are sealed by vacuum brazing.

[0042] A cavity 111 is provided in the base 101, the cooling channel 104 is located at the lower part of the cavity 111, and the heating element 102 is installed in the cavity 111, so that the inner wall of the base 101 shields the heating element 102, and the light emitted by the heating element 102 is shielded by the base 101. At the same time, the inner wall of the cavity also shields the radiation of the high-temperature heating area to the inner wall of the scanning electron microscope, which can effectively reduce the outgassing of the inner wall of the scanning electron microscope.

[0043] A boss 112 is provided on the side of the cavity 111, and a second connecting column 115 is installed on the boss 112. The connecting line of the temperature meter can be wound around the second connecting column 115 and then located above the heating element 102. The temperature meter is preferably in direct point contact with the sample, so that the measured result is more accurate. Grooves 113 are provided on both sides of the boss 112, and the first connecting column 114 is located in the groove 113, so that the two ends of the heating element 102 pass through the first connecting column 114, which is equivalent to the two ends of the heating element 102 being located in the groove 113. By designing the boss 112 and the groove 113, the connecting lines on both sides of the heating element 102 are separated from the connecting lines of the temperature meter and will not be short-circuited. The connecting lines on both sides of the heating element 102 are located outside the connecting lines of the temperature meter, which is equivalent to the entire heating element 102 surrounding the temperature meter, and the size of the heating element 102 can be designed to be relatively large, so that the heating response efficiency is faster.

[0044] The heating element 102 can be a heating wire, preferably a spiral gate type platinum-rhodium alloy, whose two pins are fixed on both sides of the boss 112, locked by a first connecting column 114 and a locking nut, and a T-shaped ceramic gasket 116 is used for heat insulation and insulation.

[0045] A reflector 105 is also installed in the cavity 111. The reflector 105 is located at the lower part of the heating element 102 and is used to reflect the heat radiated downward by the heating element 102 toward the side of the storage plate 103. The reflector 105 and the base 101 are also isolated by a ceramic gasket 116, which not only has the function of insulation but also has the function of heat insulation.

[0046] The reflector 105 of the present invention is a reflective mirror. When the heat of the heating element 102 diffuses downward, it is reflected upward by the reflective mirror, which can reduce the heat transferred to the base 101 and also make the heat used to heat the sample as much as possible, so that the heating response speed is faster, and the reflected heat heats the placement plate more evenly, so that the overall temperature difference of the sample is reduced. The heating element 102 is not in contact with the reflector 105, the upper part of the heating element 102 is not in contact with the placement plate 103, and the cavity 111 is completely isolated from the cooling channel 104.

[0047] The heating element 102 will not only generate heat but also emit light during the heating process. If the light is too strong, it will affect the imaging of the scanning electron microscope. Therefore, the present application installs a placement plate 103 on the upper part of the heating element 102. The sample is placed on the placement plate 103 during testing. Therefore, the placement plate 103 not only has the function of shading the heating element 102 but also can place the sample to prevent the sample from directly contacting and conducting electricity with the heating wire.

[0048] The placing plate 103 is located on the upper part of the heating element 102, and the placing plate 103 is used to block the light emitted by the heating element 102 and to place the sample. A gap is provided on the placing plate 103, and the bottom of the sample can be clamped in the gap to fix the sample, and the heat of the heating element 102 can pass through the gap to directly heat the sample. Compared with the heat radiation transferred to the sample through the placing plate 103, it is more efficient to heat the sample directly through the gap. A V-shaped notch is provided on the placing plate 103 of this embodiment in order to avoid the temperature measuring meter. The upper part of the placing plate 103 can be processed into different shapes according to the different shapes of samples, so that the heat of the heating element 102 can be transferred to the sample as quickly as possible.

[0049] In this embodiment, the placement plate 103 and the base 118 are both L-shaped, and both are connected to the base 101 by bolts. After the placement plate 103 is matched with the base 101, it just contacts the top of the base 101. Of course, the placement plate 103 can also be designed to be U-shaped, and there can be a certain distance between the placement plate 103 and the top of the base 101, but in this way, the heating efficiency of the heating element 102 for the sample is lower. The placement plate 103 and the base 118 are set separately, and different placement plates 103 can be replaced for different samples. The placement plate 103 and the base 118 can also be a whole, so that the number of connection holes on the base 101 can be reduced.

[0050] After the temperature is measured by the temperature meter, it is connected to the temperature controller. The temperature controller performs PID adjustment and temperature control according to the data fed back by the temperature meter. The temperature measuring point of the temperature meter should be as close to the sample surface as possible and form point contact to make the measurement result more accurate. The power supply adopts a DC temperature-controlled power supply, which integrates the temperature controller and the DC power supply into one. The power supply output is PID-controlled through the feedback of the temperature meter, which can achieve stable temperature control.

[0051] The cooling medium flowing in the cooling channel 104 may be water, liquid nitrogen or other cooling medium. The flow rate is controlled by detecting the temperature of the cooling medium in real time so that the temperature of the cooling medium is maintained within a set temperature range.

[0052] Furthermore, if Figure 5 As shown, the present invention also provides a scanning electron microscope, including the aforementioned sample in-situ heating device 100 and a scanning electron microscope body 200. The sample in-situ heating device 100 is installed on a high-precision displacement stage inside the scanning electron microscope body 200. When loading the sample, the high-precision displacement stage moves the sample in-situ heating device 100 outward. After loading, the high-precision displacement stage moves the sample in-situ heating device 100 inside the scanning electron microscope body 200.

[0053] The interior of the scanning electron microscope is in a vacuum state when in use, and it is necessary to connect the various wires of the sample in-situ heating device 100 and the pipes of the cooling medium. An adapter flange 201 is installed on the scanning electron microscope body 200, and a first interface 202, a second interface 203 and a third interface 204 are installed on the adapter flange 201. The first interface 202 is used for the wire of the temperature measuring meter to pass through, the second interface 203 is used for the wire of the heating element 102 to pass through, and the third interface 204 is provided with a pipeline connected to the cooling element. These three interfaces are connected by feedthrough vacuum connection flanges, and oxygen-free copper gaskets are used between the three interfaces and the flanges for vacuum sealing. The first flange 207, the second flange 208 and the third flange 209 are connected to the first interface 202, the second interface 203 and the third interface 204 respectively. A vacuum window can also be set on the adapter flange 201, so that the situation inside the scanning electron microscope can be observed in real time.

[0054] The third interface 204 is connected to the cooling element. Figure 7 and 8 As shown, two threaded holes are provided on the third flange 209, the threaded holes are close to the vacuum side of the scanning electron microscope, the depth of the threaded holes is about half the thickness of the third flange 209, and a step hole is reserved on the end face for convenient connection with the third interface 204. A stainless steel pipe is passed through the outside of the third flange 209, i.e., the atmospheric side, and the central channel of the stainless steel pipe is kept on the same axis as the threaded hole. The threaded hole is connected to the inlet 106 and the outlet 107 on the base 101 by a high temperature resistant hose. Both ends of the hose are sealed after being connected. When the high-precision displacement stage is moved, both ends of the hose are always sealed and do not fall off. The connection between the hose and the third flange 209 adopts a standard waterway adapter, and the material selection of the hose requires the air release rate to be as low as possible and the sealing to be good.

[0055] An electron beam generator 205 is provided in the electron microscope body. The electron beam generator 205 generates an electron beam and shoots it onto the sample. After the sample is heated, thermal electrons are generated. Therefore, a thermal electron filter grid 206 is installed at the front end of the pole shoe of the electron beam generator 205. The thermal electron filter grid 206 is connected to a power line to generate a bias voltage. Under the action of the bias voltage, the thermal electron filter grid 206 can eliminate the thermal electrons emitted by the sample at high temperature. The positive electrode of the power supply is welded to the thermal electron filter grid 206, and the negative electrode is grounded. According to the size of the set bias voltage, thermal electrons with energy higher than the set threshold are blocked to prevent the thermal electrons from affecting the imaging quality of the scanning electron microscope. The sample generates secondary electrons under the action of the electron beam emitted by the electron beam generator 205. Usually, the energy of the secondary electrons is mostly between 1eV and 5eV, depending on the different sample materials, and a few have higher energy. Thermal electrons are generated only after the sample reaches a certain temperature, and the energy is mostly no more than 1eV. When the thermal electron filter grid 206 has a negative bias voltage, thermal electrons with energy lower than the energy of overcoming the potential barrier are blocked, and secondary electrons are screened out and received by the detector. The negative bias voltage value is usually adjusted according to the observed imaging quality.

[0056] A circular hole is left in the center of the thermal electron filter grid 206 for emitting electron beams, and connecting holes are provided around the thermal electron filter grid 206 for connecting with the electron beam generating gun 205. The exterior of the thermal electron filter grid 206 is designed to be semicircular, which is equivalent to designing a gap so that it does not affect other components in the scanning electron microscope.

[0057] Instructions for use: The vacuum seal mainly relies on fluororubber and copper gaskets, and the clamping method adopts screw connection. The adapter flange 201 is installed on the side of the scanning electron microscope body. The vacuum chamber of the scanning electron microscope body 200 contains a cooling circuit, current and temperature measuring meters, and they are combined as a whole. Before vacuuming, it is necessary to check whether the electrodes of the heating element 102 are short-circuited with other parts. After waiting for the vacuum degree in the microscope to reach the system that allows imaging, the pump connected to the cooling element and the DC source electrically connected to the heating element 102 can be turned on. At this time, there is no power output. The current temperature of the power dial can be checked. The temperature controller can record the output power and temperature in real time, and the automatic and manual modes can be switched at any time. Appropriately adjust the PID parameters according to the actual heating curve.

[0058] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A sample in-situ heating device, characterized in that: include: Pedestal; A heating element, mounted on the base, and used to heat the sample; A cooling element, used to cool the base; A placing plate, located on the upper part of the heating element, and used for placing samples; The reflector is located at the lower part of the heating element, and is used to reflect the heat of the heating element toward one side of the storage plate.

2. The sample in-situ heating device according to claim 1, characterized in that: The cooling member is a cooling channel arranged in the base, and both ends of the cooling channel are respectively provided with an inlet and an outlet connected to a cooling device.

3. The sample in-situ heating device according to claim 2, characterized in that: The cooling channel includes a first channel, a second channel and a third channel. The first channel and the second channel are both connected to the third channel. The third channel extends from one side of the base to the other side. One end of the third channel is located in the base and the other end is sealed.

4. The sample in-situ heating device according to claim 1, characterized in that: A cavity is arranged in the base, and the heating element and the reflecting element are both located in the cavity.

5. The sample in-situ heating device according to claim 4, characterized in that: A boss is arranged on the base, grooves are arranged on both sides of the boss, and two ends of the heating element are respectively located in the grooves.

6. The sample in-situ heating device according to claim 1 or 4, characterized in that: Both ends of the heating element are connected to the base through a first connecting column. The first connecting column is provided with a through hole, and the heating element passes through the through hole.

7. The sample in-situ heating device according to claim 1, characterized in that: It also includes a temperature meter and a temperature controller connected to the temperature meter, wherein both ends of the temperature meter are fixed to the base through second connecting columns, the temperature meter is used to measure the temperature of the heating element, and the temperature controller is used to control the power of the heating element according to the data fed back by the temperature meter.

8. The sample in-situ heating device according to claim 1, characterized in that: A base is arranged at the bottom of the base, and a pin is arranged on a side of the base away from the base.

9. A scanning electron microscope, characterized in that It comprises a scanning electron microscope body and the sample in-situ heating device according to any one of claims 1 to 8, wherein the scanning electron microscope body is provided with an adapter flange, the adapter flange is provided with a first interface, a second interface and a third interface, the first interface is used for the wire of a temperature measuring meter to pass through, the second interface is used for the wire of a heating element to pass through, and the third interface is provided with a pipeline connected to the cooling element.

10. The scanning electron microscope according to claim 9, characterized in that An electron beam generating gun is arranged in the electron microscope body, and a thermal electron filtering grid is installed at the front end of the pole shoe of the electron beam generating gun. The thermal electron filtering grid is connected to a power line to generate a bias voltage. The thermal electron filtering grid is used to eliminate thermal electrons emitted by the sample at high temperature under the action of the bias voltage.

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