Electron beam self-heating sample stage

Abstract

The application discloses an electron beam self-heating sample table, which comprises a base and a sample support table; the base comprises a hollow base body and a hollow bracket connected with the inner wall of the base body and extending in a direction perpendicular to the base body; the sample support table is in a hollow structure and comprises a hollow sample table and a hollow connecting column arranged at the bottom of the sample table; the bracket is sleeved outside the connecting column; the hollow parts of the base body, the connecting column and the sample table form a channel for the electron beam to pass through. The sample table provided by the application can ensure that the electron beam passing through the sample is not reflected to the test sample and the measuring thermal bridge, thereby improving the accuracy of the test.

Description

Technical Field

[0001] This invention relates to the field of scanning electron microscopy, and more particularly to an electron beam self-heating sample stage. Background Technology

[0002] Electron beam self-heating testing, as a micro / nanoscale thermal conductivity measurement method, has attracted widespread attention due to its ability to obtain thermal resistance distributions with nanoscale spatial resolution. The electron beam self-heating testing method was first proposed by Professor John T.L. Thong and Professor Li Baowen's group at the National University of Singapore. This method improves upon the thermal bridge method by using an electron beam to locally heat the sample and measuring the temperature changes at both ends of the thermal bridge, thereby obtaining sample thermal resistance information with nanoscale spatial resolution [Non-Patent Literature 1]. This method avoids the contact thermal resistance effects caused by probe-sample contact in thermal scanning microscopy through a non-contact electron beam heating mode, and also avoids the experimental errors caused by contact thermal resistance between the sample and the suspended platform in the thermal bridge method. The key to this testing method lies in heating the suspended sample with a focused electron beam in scanning electron microscopy. Therefore, it is necessary to prevent the electron beam from being scattered by the substrate below after penetrating the suspended sample and onto the test sample and the measured thermal bridge. To achieve this, the test requires the sample to be suspended and the test device's sample stage to provide the longest possible electron beam transmission channel to avoid scattering and test errors.

[0003] Most current scanning electron microscope sample stages are planar sample stages designed for general morphology observation, and they fail to meet the requirements of electron beam transmission channels and sample stages for connecting to test device circuits required for electron beam self-heating testing.

[0004] Non-patent literature 1: D. Liu, R. Xie, N. Yang, B. Li, and J. T. L. Hong, “Profiling Nanowire Thermal Resistance with a Spatial Resolution of Nanometers,” Nano Lett., vol. 14, no. 2, p. 806, 2014. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides an electron beam self-heating sample stage for scanning electron microscopes. The electron beam transmission channel provided by this sample stage ensures that the electron beam passing through the sample is not reflected onto the test sample or the measurement thermal bridge, thereby improving the accuracy of the test.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] This invention provides an electron beam self-heating sample stage, including a base and a sample support stage; the base includes a hollow base body and a hollow bracket connected to the inner wall of the base body and extending on one side perpendicular to the direction of the base body; the sample support stage is a hollow structure, including a hollow sample stage and a hollow connecting column, the connecting column being disposed at the bottom of the sample stage; the bracket is sleeved on the outside of the connecting column; the base body, the connecting column, and the hollow portion of the sample stage form a channel for the electron beam to pass through.

[0008] In a preferred embodiment, the cross-section of the channel is circular;

[0009] Preferably, the diameter of the circular cross-section is ≥2mm and ≤5mm;

[0010] Preferably, the length of the channel is ≥20mm and ≤30mm;

[0011] In a preferred embodiment, the bracket is nested on the outside of the connecting column;

[0012] Preferably, the height of the bracket is the same as the height of the connecting column.

[0013] In a preferred embodiment, a fastening assembly for securing the connecting column and the bracket is also included;

[0014] Preferably, the fastening assembly includes a fastening screw; at least two through holes are provided on the side wall of the bracket, the fastening screw is disposed in the through holes, and the cylindrical end of the fastening screw abuts against the side of the connecting column;

[0015] Preferably, the at least two through holes are symmetrically distributed with respect to the axis of the bracket;

[0016] Preferably, the height of the at least two through holes is between one-third and two-thirds of the height of the bracket;

[0017] Preferably, the fastening screw is a socket head cap screw.

[0018] In a preferred embodiment, at least two U-shaped grooves are provided on the side of the base body;

[0019] Preferably, the at least two U-shaped grooves are symmetrically distributed;

[0020] Preferably, a fixing screw is provided inside the U-shaped groove.

[0021] In a preferred embodiment, a sample clamping assembly disposed on the upper surface of the sample stage is also included;

[0022] Preferably, the sample clamping assembly is an elastic assembly; the elastic assembly includes a fixed end and a clamping end; the fixed end is fixed to the upper surface of the sample stage by a nut, and the clamping end presses against the sample to be tested on the sample stage in a direction perpendicular to the upper surface of the sample stage;

[0023] Preferably, the sample clamping assembly includes at least two sets of elastic components;

[0024] Preferably, the at least two sets of elastic components are symmetrically distributed;

[0025] Preferably, the elastic component is a spring sheet.

[0026] The above technical solution has the following advantages or beneficial effects:

[0027] The electron beam self-heating sample stage provided by the present invention provides a transmission channel for the electron beam through the hollow part of the base body, the connecting column and the sample stage, ensuring that the electron beam passing through the sample will not be reflected onto the test sample or the measurement thermal bridge, thus causing test errors.

[0028] The electron beam self-heating sample stage provided by the present invention is connected to the sample support stage by a nested connection between the base and the sample support stage, which allows for flexible adjustment of the plane orientation of the sample stage and facilitates the connection of the circuit of the test device by the tester.

[0029] The electron beam self-heating sample stage provided by this invention can also have a U-shaped groove of a certain length. With the addition of fixing screws, the position of the fixing screws in the U-shaped groove can be adjusted to flexibly adapt to scanning electron microscopes with different base sizes. Attached Figure Description

[0030] The invention, its features, shape, and advantages will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings. Like reference numerals denote like parts throughout the drawings. The drawings are not intentionally drawn to scale; the focus is on illustrating the spirit of the invention.

[0031] Figure 1 This is a schematic diagram of the structure of the electron beam self-heating sample stage provided in Embodiment 1 of the present invention;

[0032] Figure 2 This is a schematic diagram of the structure of the base of the electron beam self-heating sample stage provided in Embodiment 1 of the present invention;

[0033] Figure 3 These are the front view and top view of the base of the electron beam self-heating sample stage provided in Embodiment 1 of the present invention;

[0034] Figure 4 This is a schematic diagram of the sample support stage of the electron beam self-heating sample stage provided in Embodiment 1 of the present invention;

[0035] Figure 5 These are three views of the sample support stage of the electron beam self-heating sample stage provided in Embodiment 1 of the present invention;

[0036] The figure shows: 1-base, 2-sample support platform, 3-base body, 4-bracket, 5-sample stage, 6-connecting column, (7-1, 7-2)-through hole, (8-1, 8-2, 8-3)-U-groove, 9-sample clamping assembly, (9-1, 9-2)-spring sheet, 10-fixed end, 11-clamping end, (12-1, 12-2)-nut, 13-sample to be tested. Detailed Implementation

[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Therefore, the detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the protection scope of the present invention.

[0038] In the description of this invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0039] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, a direct connection, or an indirect connection through an intermediate medium; or they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0040] Example 1:

[0041] Figure 1 The diagram shows the structure of the electron beam self-heating sample stage provided in this embodiment, including a base 1 and a sample support stage 2, some of which are not shown.

[0042] Figure 2The diagram shown is a structural schematic of the base 1 of the electron beam self-heating sample stage provided in this embodiment. Figure 3 The front view and top view are shown, with some structures not shown. The base 1 includes a hollow base body 3 and a hollow bracket 4 that is connected to the inner wall of the base body 3 and extends to one side perpendicular to the direction of the base body 1.

[0043] Figure 4 The diagram shown is a structural schematic of the sample support stage 2 of the electron beam self-heating sample stage provided in this embodiment. Figure 5 The three-view diagram is shown, with some structural details not shown. The sample support stage 2 is a hollow structure, including a hollow sample stage 5 and a hollow connecting column 6, with the connecting column 6 located at the bottom of the sample stage 5; the bracket 4 is fitted onto the outside of the connecting column 6; the base body 3, the connecting column 6, and the hollow portion of the sample stage 5 form a channel for the electron beam to pass through.

[0044] In the technical solution of this invention, the cross-section of the hollow portion of the base body 3, the connecting column 6, and the sample stage 5 forming the channel for the electron beam to pass through can be circular. That is, the base body 3 is set as an annular structure, and correspondingly, the cross-sections of the bracket 4, the sample stage 5, and the connecting column are all annular. In some specific embodiments, the optimal working distance between the scanning electron microscope probe used to receive backscattered electrons and secondary electrons and the sample 13 to be tested is 10 mm and 15 mm, respectively. To avoid electrons reflected by the base hitting the sample-suspended thermal bridge, since there is no electric field applied to the suspended thermal bridge, the electron reflection path will not be longer. Therefore, the distance between the base and the sample-suspended thermal bridge is ≥20 mm and ≤30 mm, that is, the length of the channel for the electron beam to pass through is ≥15 mm and ≤30 mm; the cross-sectional size of this channel depends on the suspended area of ​​the sample to be tested. In this embodiment, the suspended area of ​​the sample 13 is a rectangle of 0.2mm × 1mm. To facilitate the alignment of the holes during the test assembly process, the diameter of the circular cross-section of the channel through which the electron beam passes should be ≥2mm, and in this embodiment, it is set to 5mm; while the length of the channel is set to 30mm. The above settings ensure that the electron beam is not blocked or scattered when passing through the channel.

[0045] In the technical solution of this invention, the bracket 4 is nested on the outside of the connecting column 6. To facilitate assembly, in this embodiment, the outer diameter of the connecting column 6 is slightly smaller than the inner diameter of the bracket 4. To achieve nesting, the difference between the outer diameter of the connecting column 6 and the inner diameter of the bracket 4 is usually between 0.04 and 0.1 mm.

[0046] In the technical solution of the present invention, the height of the bracket 4 is the same as the height of the connecting column 6, so that when the bracket 4 and the connecting column 6 are nested together, the lower surface of the sample stage 5 can contact the bracket 4, increasing the contact area and thus maintaining the stability of the sample stage 5 during the test.

[0047] In the technical solution of this invention, the electron beam self-heating sample stage further includes a fastening assembly for securely connecting the column 6 and the bracket 4. In this embodiment, the fastening assembly includes a fastening screw (not shown in the figure). Two through holes 7-1 and 7-2 are provided on the side wall of the bracket 4, and the fastening screw is disposed within the two through holes, with the cylindrical end of the fastening screw abutting against the side of the connecting column 6. In this invention, by providing the fastening assembly, the connecting column 6 and the bracket 4 can be reinforced, thereby improving the stability of the testing process. In this embodiment, the through holes 7-1 and 7-2 are symmetrically distributed relative to the axis of the bracket 4, and their height is at half the height of the bracket 4. In other embodiments, multiple through holes can be provided, with their height ranging from one-third to two-thirds of the height of the bracket 4.

[0048] In the technical solution of this invention, three U-shaped grooves 8-1, 8-2, and 8-3 are provided on the side of the base body 3. In this embodiment, the U-shaped grooves 8-1, 8-2, and 8-3 are symmetrically distributed with respect to the center of the base body 4, and a fixing screw (not shown in the figure) can be embedded in each U-shaped groove. During testing, the electron beam self-heating platform provided by this invention is assembled and fixed together with the base of the scanning electron microscope by the fixing screw in the U-shaped groove. By adjusting the position of the fixing screw in the U-shaped groove, it can flexibly adapt to scanning electron microscopes with bases of different sizes. In other embodiments, there may also be two or more U-shaped grooves.

[0049] In the technical solution of this invention, such as Figure 4 As shown, the electron beam self-heating platform can also have a sample clamping assembly 9 on the upper surface of the sample stage 5. In this embodiment, the sample clamping assembly 9 is an elastic assembly, including spring plates 9-1 and 9-2. Each spring plate has a fixed end 10 and a clamping end 11. The fixed end is fixed to the upper surface of the sample stage 5 by nuts 12-1 and 12-2, and the clamping end 11 presses against the sample to be tested 13 carried on the sample stage 5 in a direction perpendicular to the upper surface of the sample stage 5. Spring plates 9-1 and 9-2 are symmetrically distributed with respect to the center of the upper surface of the sample stage 5. In this invention, the upper surface of the sample stage 5 is used to carry the sample to be tested 13. To fix the sample to be tested 13, elastic components such as spring plates can be used, with one end fixed to the upper surface of the sample stage 5 and the other end able to apply pressure towards the sample stage 5 to the sample to be tested 13, thereby fixing the sample to be tested. In other embodiments, three or more sets of spring plates can be provided.

[0050] The assembly and testing process of the electron beam self-heating sample stage in this embodiment is as follows:

[0051] (1) Align the three U-shaped grooves on the main body 3 of the base with the three screw holes on the sample stage base of the Thermo Fisher Apreo2S scanning electron microscope and fix them with three M2.5 hexagonal screws.

[0052] (2) Insert the connecting column 6 into the hollow bracket 4 on the base 1, adjust the position by rotating the support platform 2, and then fix the sample support platform 2 and the base 1 with the internal hexagonal set screw; thus, the hollow part of the base body 3, the connecting column 6 and the sample stage 5 form a channel for the electron beam to pass through.

[0053] (3) Place the sample to be tested 13, i.e. the integrated circuit socket test device with a hole in the middle, on the upper surface of the sample stage 5, align the middle hole of the integrated circuit socket test device with the hollow part of the sample stage, adjust the nut on the upper surface of the sample stage, and fix the sample to be tested 13 with a spring clip.

[0054] (4) Connect the sample to be tested 13 to the testing instrument via the wire inside the scanning electron microscope;

[0055] (5) After vacuuming the scanning electron microscope, turn on the electron beam, adjust the position of the sample to be tested, and focus the scanning electron microscope sample.

[0056] (6) Turn on the external testing instruments: two sets of Keithley 6221 current source meters and two sets of SRS830 lock-in amplifiers, used to measure the resistance change of the temperature detector of the suspended thermal bridge device.

[0057] (7) Linearly scan the sample to be tested, and simultaneously measure the resistance change of the temperature detector of the suspended thermal bridge device.

[0058] After the test, data analysis was performed on the information collected during the process.

[0059] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An electron beam self-heating sample stage, characterized by, The system includes a base and a sample support stage. The base comprises a hollow base body and a hollow bracket connected to the inner wall of the base body and extending to one side perpendicular to the base body. The sample support stage is a hollow structure, including a hollow sample stage and a hollow connecting column, with the connecting column located at the bottom of the sample stage. The bracket is fitted onto the outside of the connecting column. The hollow portion of the base body, the connecting column, and the sample stage form a channel for the electron beam to pass through.

2. The electron beam self-heating sample stage of claim 1, wherein, The cross-section of the channel is circular.

3. The electron beam self-heating sample stage of claim 2, wherein, The diameter of the circular cross-section is ≥2mm and ≤5mm.

4. The electron beam self-heating sample stage according to claim 2, characterized in that, The length of the channel is ≥20mm and ≤30mm.

5. The electron beam self-heating sample stage according to claim 1, characterized in that, The bracket is nested on the outside of the connecting column.

6. The electron beam self-heating sample stage according to claim 1, characterized in that, The height of the bracket is the same as the height of the connecting column.

7. The electron beam self-heating sample stage according to claim 1, characterized in that, It also includes fastening components for securing the connecting column and bracket.

8. The electron beam self-heating sample stage according to claim 7, characterized in that, The fastening assembly includes a fastening screw; at least two through holes are provided on the side wall of the bracket, the fastening screw is disposed in the through holes, and the cylindrical end of the fastening screw abuts against the side of the connecting column.

9. The electron beam self-heating sample stage according to claim 8, characterized in that, The at least two through holes are symmetrically distributed with respect to the axis of the bracket.

10. The electron beam self-heating sample stage according to claim 9, characterized in that, The height of the at least two through holes is between one-third and two-thirds of the height of the bracket.

11. The electron beam self-heating sample stage according to claim 8, characterized in that, The fastening screw is a recessed hexagonal set screw.

12. The electron beam self-heating sample stage according to claim 1, characterized in that, The base body has at least two U-shaped grooves on its side.

13. The electron beam self-heating sample stage according to claim 12, characterized in that, The at least two U-shaped grooves are symmetrically distributed.

14. The electron beam self-heating sample stage according to claim 12, characterized in that, The U-shaped groove is equipped with fixing screws.

15. The electron beam self-heating sample stage according to claim 1, characterized in that, It also includes a sample clamping assembly disposed on the upper surface of the sample stage.

16. The electron beam self-heating sample stage according to claim 15, characterized in that, The sample clamping assembly is an elastic assembly; the elastic assembly includes a fixed end and a clamping end; the fixed end is fixed to the upper surface of the sample stage by a nut, and the clamping end presses against the sample to be tested on the sample stage in a direction perpendicular to the upper surface of the sample stage.

17. The electron beam self-heating sample stage according to claim 16, characterized in that, The sample clamping assembly includes at least two sets of elastic components.

18. The electron beam self-heating sample stage according to claim 17, characterized in that, The at least two sets of elastic components are symmetrically distributed.

19. The electron beam self-heating sample stage according to claim 17, characterized in that, The elastic component is a spring sheet.

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