A vacuum sample holder with adjustable grid voltage

Abstract

This invention discloses an adjustable grid voltage vacuum sample holder, comprising a top connector, a middle ceramic component, a first electrode, a second electrode, and a third electrode. The top connector is fixed to the center of the top of the middle ceramic component by a first bolt. The first, second, and third electrodes are evenly distributed around the top connector and fixed to the middle ceramic component. A first, second, and third electrical interface are fixed to the bottom of the middle ceramic component. This invention significantly improves structural stability by designing the third electrode and the top connector as a single unit and using two second bolts above the third electrode and a first bolt below the middle ceramic component to jointly fix the top connector and the middle ceramic component. This design avoids axial rotation between the top connector and the middle ceramic component, resulting in a more secure connection.

Description

Technical Field

[0001] This invention relates to the field of high-quality two-dimensional thin film material preparation technology, and in particular to a vacuum sample holder with adjustable gate voltage. Background Technology

[0002] In the field of high-quality two-dimensional thin film material preparation and characterization, a vacuum environment is required because the atmosphere affects the preparation quality and physical properties of the thin film. Generally speaking, the higher the vacuum level, the higher the material preparation quality, and the less easily the material properties are altered. Equipment used for thin film material preparation includes molecular beam epitaxy (MBE) and pulsed laser deposition (PLD), while characterization equipment includes scanning tunneling microscopy (STM) and angle-resolved photoelectron spectroscopy (ARPES).

[0003] Material preparation requires a substrate, which is then placed into a material growth apparatus for material growth to produce a sample. This sample is then transferred to a material characterization apparatus for property measurement and characterization. However, researchers cannot physically reach into a vacuum system to transfer or manipulate the sample. Therefore, a sample holder (a small device for holding the substrate or sample) and a sample transfer mechanism (a method for transferring and manipulating the sample holder within a vacuum) are needed to replace researchers' hands in moving and controlling the sample in a vacuum.

[0004] Currently, several relatively universal sample holder structures exist in ultra-high vacuum systems (especially in molecular beam epitaxy, scanning tunneling microscopy, and angle-resolved photoelectron spectroscopy). However, existing sample holders are prone to screw loosening during temperature-dependent measurements, resulting in poor temperature stability and affecting precise electronic measurements (such as those performed by scanning tunneling microscopy). This patent application upgrades one such structure, significantly improving its temperature stability. Summary of the Invention

[0005] To address the problems mentioned in the background section, the present invention provides a vacuum sample holder with adjustable gate voltage.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] An adjustable grid voltage vacuum sample holder includes a top connector, a middle ceramic component, a first electrode, a second electrode, and a third electrode. The top connector is fixed to the top center of the middle ceramic component by a first bolt. The first, second, and third electrodes are evenly distributed around the top connector and fixed to the middle ceramic component. The bottom of the middle ceramic component is respectively fixed with a first electrical interface, a second electrical interface, and a third electrical interface. The first electrical interface is located directly below and electrically connected to the first electrode. The second electrical interface is located directly below and electrically connected to the second electrode. The third electrical interface is located directly below and electrically connected to the third electrode. The first, second, and third electrodes are insulated from each other. The third electrode is fixed to the top connector. A sample is fixed to the bottom of the middle ceramic component, and both the first and second electrical interfaces are in contact with the sample.

[0008] Preferably, the first electrode, the second electrode, and the third electrode are all fixed to the intermediate ceramic component by two second bolts, and the first electrical interface, the second electrical interface, and the third electrical interface are also connected to the intermediate ceramic component by second bolts, with the second bolts serving as electrical connections.

[0009] Preferably, the top end of the intermediate ceramic component is fixed with an isolation protrusion ring outside the top connector, and the isolation protrusion ring separates the first electrode and the second electrode from the top connector.

[0010] Preferably, the bottom end of the third electrode has a groove corresponding to the isolation protrusion, and the isolation protrusion is engaged in the groove.

[0011] Preferably, the top connector is a cylindrical structure, and a gripping rod is fixed on the top connector. The gripping rod passes horizontally through the top connector, and both ends of the gripping rod extend to the outside of the top connector.

[0012] Preferably, the top connector has a positioning hole at its top end, a first locking threaded hole at the middle position of the gripping rod, a third bolt is installed in the positioning hole, and the bottom end of the third bolt extends into the first locking threaded hole.

[0013] Preferably, the first electrode, the second electrode, and the third electrode are all fixed with positioning protrusions on the side away from the top connector.

[0014] Preferably, the bottom ends of the first electrical interface and the second electrical interface are both fixed with pressure plates by the fourth bolts, and the two pressure plates press the sample tightly and fix it to the bottom ends of the first electrical interface and the second electrical interface from both sides of the bottom end of the sample.

[0015] Preferably, the top of the top connector has a through second locking threaded hole, through which the gripping rod passes. The gripping rod has an external thread corresponding to the second locking threaded hole.

[0016] Preferably, the thickness of the third electrical interface is lower than that of the first and second electrical interfaces. A support is fixed to the bottom of the first bolt. The bottom of the third electrical interface is flush with the bottom of the support. A support plate is fixed between the third electrical interface and the bottom of the support by a fourth bolt. A gold foil is provided on the side of the support plate near the sample. An indium layer is coated on the side of the sample near the support plate. The sample and the support plate are connected by a platinum wire. The support plate is a 0.5mm thick molybdenum plate, and the gold foil is 0.1mm thick.

[0017] Compared with the prior art, the beneficial effects of the present invention are:

[0018] 1. By designing the third electrode and the top connector as a single unit, and using two second bolts above the third electrode and a first bolt below the intermediate ceramic component to jointly secure the top connector and the intermediate ceramic component, the stability of the structure is significantly improved. This design avoids axial rotation between the top connector and the intermediate ceramic component, making the connection more robust.

[0019] 2. In some technologies, the top connector and the middle ceramic component are only fixed by the fifth bolt installed at the bottom of the middle ceramic component. If only one screw is used, axial rotation will occur, which will prevent the top connector and the middle ceramic component from being fixed to each other. Therefore, the existing design uses three fifth bolts. However, due to limited space, only M1.2 bolts can be placed. In this solution, a larger screw (such as M1.6 or larger) is used at the bottom of the middle ceramic component, which enhances the engagement stability of the screw thread and reduces the risk of stripping.

[0020] 3. The isolation ring is inserted into the groove of the third electrode, achieving three-sided contact and increasing friction. This ensures that the structure maintains stable engagement during heating and cooling, further improving the overall structural stability.

[0021] 4. Considering the differences in thermal expansion and contraction of different materials (such as molybdenum, ceramics, and titanium) during temperature changes, this design uses three screws on two planes to press inwards, which better overcomes this difference and makes the structure more stable during temperature changes.

[0022] 5. The sample can be connected to the third electrical interface through the indium, platinum wire, and gold foil on its surface. The third electrode can be used to apply back grid voltage control to the sample, which can expand the measurement function of the instrument. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is an exploded view of the present invention;

[0025] Figure 2 This is the front view of the present invention;

[0026] Figure 3 This is a front-view sectional view of the present invention;

[0027] Figure 4 This is a top view of the present invention;

[0028] Figure 5 This is a bottom view of the present invention;

[0029] Figure 6 This is a bottom view of the present invention (with sample removed);

[0030] Figure 7 This is a perspective view of the present invention.

[0031] Figure 8 A bottom view of existing technology;

[0032] Figure 9 A top view of the existing technology;

[0033] Figure 10 For sample holder structure stability, the spectrum at low noise (full frequency noise below 100 fm / sqrt(Hz));

[0034] Figure 11 The sample holder screws were loose, causing an increase in low-frequency noise (the noise within 100Hz was already higher than 250fm / sqrt(Hz), and the looser the screws, the louder the noise).

[0035] Figure 12 These are cross-sectional views of Embodiments 5 and 6 of the present invention;

[0036] Figure 13 These are perspective views of Embodiments 5 and 6 of the present invention;

[0037] In the figure: 1 Top connector, 2 First electrode, 201 Second electrode, 202 Third electrode, 203 Positioning protrusion, 204 Second bolt, 205 Groove, 3 Gripping round bar, 301 First locking threaded hole, 302 Third bolt, 303 Positioning hole, 304 External thread, 305 Second locking threaded hole, 4 Intermediate ceramic part, 401 Isolation protrusion ring, 402 First bolt, 403 Support, 404 Support plate, 405 Fourth bolt, 5 Third electrical interface, 501 First electrical interface, 502 Second electrical interface, 6 Sample, 7 Electrode A, 701 Electrode B, 702 Electrode C. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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 some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] Example 1

[0040] Reference Figure 1-9 An adjustable grid voltage vacuum sample holder includes a top connector 1, a middle ceramic component 4, a first electrode 2, a second electrode 201, and a third electrode 202. The top connector 1 is fixed to the top center of the middle ceramic component 4 by a first bolt 402. The first electrode 2, the second electrode 201, and the third electrode 202 are evenly distributed around the top connector 1 and fixed to the middle ceramic component 4. The bottom end of the middle ceramic component 4 is respectively fixed with a first electrical interface 501, a second electrical interface 502, and a third electrical interface 502. The first electrical interface 501 is located at the first electrode 201. The first electrode 2, the second electrode 201 and the third electrode 202 are electrically connected to each other. The third electrode 202 is located directly below the second electrode 201 and is electrically connected to the second electrode 201. The third electrode 202 is located directly below the third electrode 202 and is electrically connected to the third electrode 202. The first electrode 2, the second electrode 201 and the third electrode 202 are insulated from each other. The third electrode 202 is fixed to the top connector 1. The bottom end of the middle ceramic part 4 is fixed with the sample 6, and both the first electrical interface 501 and the second electrical interface 502 are in contact with the sample 6.

[0041] The first electrode 2, the second electrode 201, and the third electrode 202 are all fixed to the intermediate ceramic component 4 by two second bolts 204. The first electrical interface 501, the second electrical interface 502, and the third electrical interface 5 are also connected to the intermediate ceramic component 4 by the second bolts 204, which serve as electrical connections.

[0042] The first electrode 2, the second electrode 201, and the third electrode 202 can transmit the sample signal inside the sample 6 to the external circuit, or lead the external current to the sample through the electrodes to achieve the heating function. Since the first electrical interface 501 and the second electrical interface 502 are both in contact with the sample 6, the sample 6 is electrically connected to the first electrode 2 and the second electrode 201. The third electrode 202 serves as a backup electrode. The intermediate ceramic part 4 is used to isolate the electrical connection between the upper and lower parts, and at the same time, all parts are assembled into a whole.

[0043] The third electrode 202 and the top connector 1 are connected as a whole and can still be used as a backup electrode, as in the prior art (see reference). Figure 9 In the bracket, the three electrodes—electrode A 7, electrode B 701, and electrode C 702—are independent and not connected to the top connector 1 in the middle. This results in poor overall stability of the bracket. In existing technology, the top connector 1 and the middle ceramic component 4 are only fixed by a fifth bolt 6 installed at the bottom of the middle ceramic component 4. Using only one bolt would cause axial rotation, preventing the top connector 1 and the middle ceramic component 4 from being fixed together. Therefore, the existing design uses three fifth bolts 6, but space is limited, only M1.2 bolts can be placed. In this solution, the top connector 1 and the third electrode 202 form a single component. The two second bolts 204 above the third electrode 202 and the first bolt 402 below the middle ceramic component 4 work together to fix the top connector 1 and the middle ceramic component 4. Since the third electrode 202 is fixed to the middle ceramic component 4 by the second bolts 204, the top connector 1 and the middle ceramic component 4 will no longer rotate axially. The first bolt 402 can be M1.6 or larger (if there is sufficient space).

[0044] In the existing technology, the fifth bolt 6 is made of molybdenum, the middle ceramic part 4 is made of ceramic, and the top connector 1 is generally made of titanium. During the temperature change process, there is a difference in thermal expansion and contraction, and repeated temperature changes will cause the screw to loosen.

[0045] Compared with existing technologies, it has two advantages: 1. The larger the screw, the more stable the engagement at the thread. M1.2 screws cannot be tightened with force, as this will cause stripping. 2. In existing technologies, three fifth bolts 6 on one plane are tightened in one direction. In this solution, three screws on two planes are pressed towards the middle, which can better overcome the difference in thermal expansion and contraction between different materials, making the structure more stable and more stable during temperature changes.

[0046] The top connector 1 serves as the part that the robot arm grasps when transferring samples in a vacuum;

[0047] Example 2

[0048] Reference Figure 1-9The difference between this embodiment and embodiment 1 is that the top of the middle ceramic part 4 is fixed with an isolation protrusion ring 401 on the outside of the top connector 1. The isolation protrusion ring 401 separates the first electrode 2 and the second electrode 201 from the top connector 1. The bottom end of the third electrode 202 is provided with a groove 205 corresponding to the isolation protrusion ring 401, and the isolation protrusion ring 401 is stuck in the groove 205.

[0049] The isolation ring 401 can prevent electrical interference, as described in the prior art (refer to...). Figure 9 The isolation ring 401 can only prevent electrical interference. The top connector 1 only contacts the isolation ring 401 on one side, which makes it easy to slide. In this solution, since the isolation ring 401 is stuck in the groove 205, the groove 205 and the isolation ring 401 are in contact on three sides, resulting in greater friction. Moreover, regardless of heating or cooling, it is easier to engage, thereby further improving its structural stability.

[0050] Example 3

[0051] Reference Figure 1-9 The top connector 1 is a cylindrical structure. A gripping rod 3 is fixed on the top connector 1. The gripping rod 3 passes horizontally through the top connector 1, and both ends of the gripping rod 3 extend to the outside of the top connector 1. A positioning hole 303 is opened at the top of the top connector 1, and a first locking threaded hole 301 is opened at the middle position of the gripping rod 3. A third bolt 302 is installed in the positioning hole 303, and the bottom end of the third bolt 302 extends into the first locking threaded hole 301.

[0052] When transferring samples, the robotic arm is equipped with a sleeve corresponding to the top connector 1, and the sleeve is equipped with a hanging groove for holding and gripping the round bar 3. The first electrode 2, the second electrode 201 and the third electrode 202 are all fixed with positioning protrusions 203 on the side away from the top connector 1. The robotic arm is equipped with pressure plates corresponding to the positioning protrusions 203. The positioning protrusions 203 can be respectively locked into the three pressure plates to achieve overall fixation and make electrical connection with the outside.

[0053] Example 4

[0054] Reference Figure 1-9 The bottom ends of the first electrical interface 501 and the second electrical interface 502 are both fixed with pressure plates 601 by the fourth bolt 602. The two pressure plates 601 press the sample 6 tightly and fix it to the bottom ends of the first electrical interface 501 and the second electrical interface 502 from both sides of the bottom end of the sample 6 respectively.

[0055] It can ensure the stability of the sample during the test and allows for easy disassembly and installation of sample 6. During the sample measurement process, the sample holder structure must maintain high mechanical strength and stability; otherwise, it will exhibit obvious noise signals during the test, affecting the measurement structure.

[0056] Example 5

[0057] Reference Figure 12 and 13 The difference between this embodiment and embodiment 3 is that the top of the top connector 1 has a through second locking threaded hole 305. The gripping rod 3 passes through the top connector 1 through the second locking threaded hole 305, and the outside of the gripping rod 3 has an external thread 304 corresponding to the second locking threaded hole 305. In embodiment 3, the gripping rod 3 is fixed by the third bolt 302, the contact surface is very small, and it is very easy to loosen. In this embodiment, the gripping rod 3 is directly screwed onto the top connector 1, and there is a larger contact surface between the gripping rod 3 and the top connector 1, making the structure more stable.

[0058] Example 6

[0059] Reference Figure 12 and 13 The difference between this embodiment and Embodiment 1 is that the thickness of the third electrical interface 5 is lower than the thickness of the first electrical interface 501 and the second electrical interface 502. A support member 403 is fixed to the bottom end of the first bolt 402. The bottom end of the third electrical interface 5 is flush with the bottom of the support member 403. A support plate 404 is fixed between the third electrical interface 5 and the bottom end of the support member 403 by a fourth bolt 405. A gold foil is provided on the side of the support plate 404 near the sample 6. An indium layer is coated on the side of the sample 6 near the support plate 404. The sample 6 and the support plate 404 are connected by a platinum wire. 04 is a 0.5mm thick molybdenum plate, and the gold foil is 0.1mm thick. Sample 6 can be connected to the third electrical interface 5 through the indium, platinum wire, and gold foil on its surface. The third electrode 202 can be used to apply back grid voltage control to sample 6, which can expand the measurement function of the instrument. Although indium melts at around 160℃, it does not affect the contact of the platinum wire. However, when the temperature exceeds 500℃, its own vapor pressure (thermal evaporation) will affect the material growth. Therefore, the sample heating temperature in this design will be limited (the temperature must not exceed 500℃), but it can still meet the growth requirements of many thin film materials.

[0060] Molecular beam epitaxy is a fabrication technique for preparing high-quality two-dimensional thin film materials in an ultra-high vacuum environment.

[0061] Scanning tunneling microscopy is a characterization technique for measuring thin film materials prepared by molecular beam epitaxy in an ultra-high vacuum environment. It is generally directly connected to the molecular beam epitaxy equipment and is in the same ultra-high vacuum environment. The sample does not come into contact with the atmosphere from preparation to measurement. The transfer of the sample between different systems requires a sample holder.

[0062] Molecular beam epitaxy requires high-temperature heating of samples, while scanning tunneling microscopy requires low-temperature cooling and measurement of samples. During repeated heating and cooling processes, loose screws on the sample holder can significantly affect the measurements of precision characterization equipment such as scanning tunneling microscopes.

[0063] Gate voltage, applied to the back side of an insulating substrate (the front side is used for growing thin film materials), allows for the manipulation of chemical potential, carrier concentration, and quantum transport properties of the thin film material. This is crucial for materials research. However, current gate voltage manipulation is primarily used for in-situ measurements outside of vacuum. Performing gate voltage manipulation on externally introduced samples within an ultra-high vacuum remains a significant challenge.

[0064] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used 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.

[0065] In this invention, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," "link," and "fix" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, a direct connection, or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0066] The control method of this invention is automatic control through a controller. The control circuit of the controller can be implemented by simple programming by those skilled in the art. The power supply is also common knowledge in the art. Furthermore, since this invention is mainly used to protect mechanical devices, the control method and circuit connection will not be explained in detail here.

[0067] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A vacuum sample holder with adjustable grid voltage, comprising a top connector (1), a middle ceramic component (4), a first electrode (2), a second electrode (201), and a third electrode (202), characterized in that: The top connector (1) is fixed to the top center of the intermediate ceramic part (4) by the first bolt (402). The first electrode (2), the second electrode (201), and the third electrode (202) are evenly distributed around the top connector (1) and fixed to the intermediate ceramic part (4). The bottom of the intermediate ceramic part (4) is respectively fixed with the first electrical interface (501), the second electrical interface (502), and the third electrical interface (5). The first electrical interface (501) is located directly below the first electrode (2) and is electrically connected to the first electrode (2). The electrical interface (502) is located directly below the second electrode (201) and is electrically connected to the second electrode (201). The third electrical interface (5) is located directly below the third electrode (202) and is electrically connected to the third electrode (202). The first electrode (2), the second electrode (201), and the third electrode (202) are insulated from each other. The third electrode (202) is fixed to the top connector (1). The sample (6) is fixed at the bottom of the middle ceramic part (4). Both the first electrical interface (501) and the second electrical interface (502) are in contact with the sample (6). The first electrode (2), the second electrode (201) and the third electrode (202) are all fixed to the intermediate ceramic part (4) by two second bolts (204), and the first electrical interface (501), the second electrical interface (502) and the third electrical interface (5) are also connected to the intermediate ceramic part (4) by the second bolts (204), and the second bolts (204) serve as electrical connections.

2. The adjustable grid voltage vacuum sample holder according to claim 1, characterized in that: The top of the intermediate ceramic part (4) is fixed with an isolation protrusion ring (401) outside the top connector (1). The isolation protrusion ring (401) separates the first electrode (2) and the second electrode (201) from the top connector (1).

3. The adjustable grid voltage vacuum sample holder according to claim 2, characterized in that: The bottom end of the third electrode (202) is provided with a groove (205) corresponding to the isolation protrusion ring (401), and the isolation protrusion ring (401) is stuck in the groove (205).

4. The adjustable grid voltage vacuum sample holder according to claim 1, characterized in that: The top connector (1) is a cylindrical structure. A gripping rod (3) is fixed on the top connector (1). The gripping rod (3) passes horizontally through the top connector (1), and both ends of the gripping rod (3) extend to the outside of the top connector (1).

5. A vacuum sample holder with adjustable grid voltage according to claim 4, characterized in that: The top connector (1) has a positioning hole (303) at its top end, and a first locking threaded hole (301) is provided at the middle position of the gripping round bar (3). A third bolt (302) is installed in the positioning hole (303), and the bottom end of the third bolt (302) extends into the first locking threaded hole (301).

6. A vacuum sample holder with adjustable grid voltage according to claim 4, characterized in that: The first electrode (2), the second electrode (201) and the third electrode (202) are all fixed with positioning protrusions (203) on the side away from the top connector (1).

7. A vacuum sample holder with adjustable grid voltage according to claim 4, characterized in that: The bottom ends of the first electrical interface (501) and the second electrical interface (502) are both fixed with pressure plates (601) by the fourth bolt (602). The two pressure plates (601) press the sample (6) tightly from both sides of the bottom end of the sample (6) to fix the sample (6) to the bottom ends of the first electrical interface (501) and the second electrical interface (502).

8. A vacuum sample holder with adjustable grid voltage according to claim 4, characterized in that: The top of the top connector (1) is provided with a through second locking threaded hole (305), and the gripping round bar (3) passes through the top connector (1) through the second locking threaded hole (305), and the outside of the gripping round bar (3) is provided with an external thread (304) corresponding to the second locking threaded hole (305).

9. A vacuum sample holder with adjustable grid voltage according to claim 1, characterized in that: The thickness of the third electrical interface (5) is lower than that of the first electrical interface (501) and the second electrical interface (502). The bottom end of the first bolt (402) is fixed with a support member (403). The bottom end of the third electrical interface (5) is flush with the bottom of the support member (403). The bottom end of the third electrical interface (5) and the support member (403) are fixed with a support plate (404) by a fourth bolt (405). The side of the support plate (404) near the sample (6) is provided with gold foil. The side of the sample (6) near the support plate (404) is coated with a layer of indium. The sample (6) and the support plate (404) are connected by platinum wire.

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