Manipulators and methods for handling samples

Abstract

The present invention relates to an assembly comprising a manipulator and a cooling unit. The manipulator comprises a holder for a sample and a thermal mass member arranged in thermal contact with the holder. The manipulator is configured to place the manipulator in a heat exchange position, in which the thermal mass member is in thermal contact with the cooling unit, and the manipulator is configured to move the manipulator from the heat exchange position to a manipulating position, in which the thermal mass member is thermally separated from the cooling unit. The present invention also relates to an inspection device of a focused ion beam device comprising such an assembly, and a method of using such an assembly.

Description

Technical Field

[0001] The present invention relates to a manipulation device for processing samples, in particular cryogenic samples. In addition, the present invention relates to a method for processing samples, in particular cryogenic samples. Background Art

[0002] Manipulators for handling cryogenic samples are known in the art. Such devices are used, for example, to handle small and fragile samples at low temperatures, for example to study them in examination devices such as electron microscopes.

[0003] In order to study samples at cryogenic temperatures in an electron microscope, the manipulator used needs to be cooled in order to ensure that the sample remains at said cryogenic temperature at least during the time the sample is studied. Such samples cannot be handled with a manipulator at room temperature, as this would immediately heat the sample and devitrify (i.e. destroy) it.

[0004] Although the sample and manipulator can be cooled by immersion in a cryogenic liquid (such as liquid nitrogen), this requires the use of a separate, isolated cooling chamber to prevent released nitrogen from contaminating and / or compromising the vacuum in the inspection equipment, particularly in an electron microscope.

[0005] To ensure that the sample is kept at the required cold temperature, the manipulator may alternatively comprise a sample holding unit connected to a cooling unit. The cooling unit is configured for actively cooling the sample holding unit, preferably for actively cooling the sample holding unit to a cryogenic temperature.

[0006] In order to provide active cooling of the sample holding unit, US2009 / 0000400 A1 describes a device in which the sample holding unit is connected to a cooling unit or a heat sink via a heat transfer member, such as a braid comprising a thermally conductive material. Active cooling of the cooling unit or heat sink via the braid can ensure that the surface contacting the cryogenic sample is cold. The braid should preferably not be made very long, since a longer braid represents a higher heat load. Summary of the invention

[0007] A disadvantage of using braid is that it limits the freedom of movement of the manipulator.

[0008] The object of the present invention is to at least partially obviate at least one disadvantage of conventional manipulators for cryogenic applications.

[0009] According to a first aspect, the present invention provides an assembly comprising a handling device and a cooling unit;

[0010] wherein the manipulator comprises a holder for the sample and a thermal mass member arranged in thermal contact with the holder;

[0011] The manipulation device is configured to position the manipulation device in a heat exchange position in which the thermal mass component is in thermal contact with the cooling unit and to move the manipulation device from the heat exchange position to a manipulation position in which the thermal mass component is thermally separated from the cooling unit.

[0012] In the assembly of the present invention, the manipulator, in particular a holder for the sample, is separated from the cooling unit when the manipulator is in or moved into the manipulating position. Thus, the manipulator can be moved substantially freely, since at least when the manipulator is in or moved into the manipulating position, the manipulator is not connected to the cooling unit via the heat transfer member. Due to the thermal mass member, which is preferably fixedly connected to the holder, when the holder is thermally separated from the cooling unit (e.g. when processing the sample), the increase in the temperature of the holder is at least reduced, preferably substantially prevented. Due to the thermal mass member, the braid for connecting the holder to the cooling unit can be omitted.

[0013] When handling cryogenic samples, the holder also needs to be at cryogenic temperature in order to at least substantially prevent the sample from being heated by the holder. It should be noted that a temperature increase of the cryogenic sample is acceptable as long as the temperature remains below a temperature that could cause changes in the sample's morphology. For example, for vitrification of biological samples for electron microscopy, the specimen is frozen by rapid cooling, which immediately fixes the cells in an amorphous glassy phase in which all cellular components remain in a state close to life. If the cooling rate during vitrification is too low or the sample is heated, an irreversible phase transition of water to cubic or hexagonal ice will occur and destroy the sample. This phase transition may already occur at -140 degrees Celsius.

[0014] Thus, by positioning the manipulator in the heat exchange position, the thermal mass member is in thermal contact with the cooling unit, and thus the cooling unit can actively cool the thermal mass member and the holder in thermal contact with the thermal mass member. After the holder and the thermal mass member have been cooled to a desired temperature (e.g., to a cryogenic temperature), the manipulator is ready to process a cryogenic sample. Thus, the manipulator can be moved to a manipulating position in which the thermal mass member is thermally separated from the cooling unit and in which the manipulator can be freely moved to process and / or hold a cryogenic sample using the holder.

[0015] Preferably, the thermal mass component, in particular the thermal capacity of the thermal mass component, is configured to substantially maintain a low temperature of the holder when the holder is thermally separated from the cooling unit.

[0016] In one embodiment, the thermal mass component comprises a first heat transfer surface and the cooling unit comprises a second heat transfer surface, wherein the assembly is configured such that in the heat exchange position, the first heat transfer surface is arranged in thermal contact with the second heat transfer surface. Preferably, the first heat transfer surface and the second heat transfer surface are configured to provide heat transfer between the cooling unit and the thermal mass component. In one embodiment, when the handling device is in the heat exchange position, the first heat transfer surface is configured to abut against the second heat transfer surface.

[0017] In one embodiment, the manipulator comprises one or more actuators for moving the holder, and a thermal insulation member, wherein the thermal insulation member is arranged between the one or more actuators and the holder. Due to the use of the thermal insulation member, the one or more actuators are at least substantially prevented from also being cooled by the cooling unit.

[0018] In one embodiment, the thermal mass member is arranged between the thermal insulation member and the retainer. Preferably, the thermal insulation member is arranged directly adjacent to the thermal mass member. Therefore, when the handling device is in the heat exchange position, the thermal insulation member substantially limits the part of the handling device cooled by the cooling unit to the thermal mass member and the retainer.

[0019] In one embodiment, the thermal mass member includes a chamber at least partially filled with a phase change material. In one embodiment, the phase change material includes a phase change at a predetermined low temperature, which is suitable for substantially preventing the morphology of the sample or the material surrounding the sample from changing. The phase change material can store a large amount of thermal energy during a phase change (such as from a solid to a liquid). Advantageously, a large amount of thermal energy can be stored at a relatively constant temperature when a phase change occurs. Therefore, the use of a phase change material can provide temperature stabilization by storing a large amount of thermal energy without significantly changing the temperature.

[0020] In one embodiment, the phase change material comprises a phase that changes from solid to liquid at said predetermined low temperature. In the phase change from solid to liquid, the volume of the phase change material will not change to a large extent, and therefore there is only a relatively low pressure accumulation in the chamber due to this phase change.

[0021] In embodiments where the sample comprises water frozen to ice at cryogenic temperatures, the phase change material comprises a phase change at a temperature below the point at which the morphology of the ice changes, preferably below -140 degrees Celsius. In one embodiment, the morphology of the ice changes from an amorphous form to a cubic crystalline form. Such a change in the morphology of the ice, e.g., from amorphous ice to cubic crystalline ice, may damage the sample, and it is desirable to prevent such a change in morphology as much as possible.

[0022] According to a second aspect, the invention provides an inspection system and / or a focused ion beam system, wherein the microscope system comprises a sample compartment configured to substantially surround the sample, wherein the sample compartment comprises a component as described above, wherein the component is at least partially arranged in the sample compartment.

[0023] The assembly of the present invention as described above is particularly advantageous for use in inspection systems and / or focused ion beam systems. In particular for processing small samples in electron microscopes, the manipulator is small and can therefore only carry a limited load. In the case of using braids to connect the manipulator to a cooling unit (such as a cold finger or a radiator), these braids are relatively stiff and therefore limit the load-bearing capacity of the manipulator. In addition, these braids severely limit the degrees of freedom and total range of motion of the manipulator. Due to the thermal mass component of the manipulator of the present invention, the braid used to connect the holder to the cooling unit can be omitted, and the limitation of the degrees of freedom of moving the manipulator is eliminated.

[0024] In one embodiment, the cooling unit is arranged against or in a wall of the sample compartment. Preferably, the cooling unit is arranged at a position in the sample compartment such that the thermal mass member may occasionally interface with the cooling unit, and preferably the position of the cooling unit does not interfere with the movement of the manipulator when handling and / or moving the sample in the sample compartment.

[0025] In one embodiment, the system comprises a sample holding unit, wherein the cooling unit is connected to the sample holding unit, or wherein the cooling unit is an integral part of the sample holding unit. Thus, the system requires only one cooling unit to cool both the sample in the sample holding unit and the thermal mass member of the manipulator.

[0026] In one embodiment, the inspection system includes an electron microscope.

[0027] In one embodiment, the sample compartment comprises a vacuum chamber.

[0028] According to a third aspect, the invention provides a method of using an assembly comprising a manipulator and a cooling unit, wherein the manipulator comprises a holder for a sample and a thermal mass member arranged in thermal contact with the holder, wherein the method comprises the following steps:

[0029] placing the manipulator in a heat exchange position in which the thermal mass member is in thermal contact with the cooling unit; and

[0030] The operating device is moved from the heat exchange position to an operating position in which the thermal mass component is thermally decoupled from the cooling unit.

[0031] In one embodiment, the thermal mass member comprises a first heat transfer surface and the cooling unit comprises a second heat transfer surface, wherein the first heat transfer surface is positioned in thermal contact with the second heat transfer surface when the assembly is in the heat exchange position.

[0032] In one embodiment, when the operator is in the heat exchange position, the first heat transfer surface abuts against the second heat transfer surface.

[0033] The various aspects and features described and shown in the specification can be applied separately wherever possible. These individual aspects, in particular the aspects and features described in the attached dependent claims, can become the subject of divisional patent applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The invention will be explained on the basis of exemplary embodiments shown in the accompanying drawings, in which:

[0035] Figure 1 A first example of an assembly of the invention is schematically shown in a heat exchange position;

[0036] Figure 2 Schematically shows the Figure 1 Components;

[0037] Figure 3A and Figure 3B schematically showing various side views of a second example of an assembly according to the invention; and

[0038] Figure 4 A third example of an assembly according to the invention is schematically shown. DETAILED DESCRIPTION

[0039] Figure 1 Schematically, an assembly comprising a manipulator 1 and a cooling unit 2 is shown. The manipulator 1 comprises a holder 3 for a sample and a thermal mass member 4 arranged in thermal contact with the holder 3. In this example, the holder 3 is configured as a pair of tweezers, however, other known holders for holding or manipulating a sample or a part thereof may also be applied in the manipulator 1. The thermal mass member is fixedly connected to the holder.

[0040] The manipulator 1 comprises one or more actuators 5 and an arm 6, the actuator 5 being used to move the holder 3. The arm 6 is arranged between the one or more actuators 5 and the holder 3. Preferably, the arm 6 comprises a thermal insulation member which allows thermal isolation of the holder 3 from the one or more actuators 5. In particular, the thermal mass member 4 is arranged between the arm 6 and the holder 3. Figure 1 As schematically shown in FIG. 4 , the arm 6 is arranged directly adjacent to the thermal mass component 4 .

[0041] In this example, the thermal mass member 4 is made of a material with a high heat capacity. As a result, the thermal mass member 4 can be made of a wide variety of materials. The most important factor is the thermal conductivity of the material. The thermal conductivity needs to be high enough to ensure that the thermal mass member 4 is cooled to a cryogenic temperature in a reasonably short duration. Preferably, the thermal mass member 4 is at least partially made of a metallic material, such as copper or aluminum, which has both a high heat capacity and a high thermal conductivity.

[0042] The thermal mass member 4 comprises a first heat transfer surface 41, and the cooling unit 2 comprises a second heat transfer surface 21. The assembly is configured such that, in the heat exchange position, the first heat transfer surface 41 is arranged in thermal contact with the second heat transfer surface 21, such as Figure 1 In this position, the first heat transfer surface 41 and the second heat transfer surface 21 are configured to provide heat transfer between the cooling unit 2 and the thermal mass member 4. Figure 1 In the example of , the first heat transfer surface 41 abuts against the second heat transfer surface 21 when the handling device 1 is in the heat exchange position.

[0043] When the operating device 1 is in Figure 1 When the thermal mass member 4 is in the heat exchange position, the thermal mass member 4 is in thermal contact with the cooling unit 2, and the cooling unit 2 can actively cool the thermal mass member 4 and the holder 3 in thermal contact with the thermal mass member 4. After the holder 3 and the thermal mass member 4 have been cooled to a desired temperature (e.g., to a cryogenic temperature), the manipulator 1 is ready to process a cryogenic sample.

[0044] Therefore, the operating device 1 can be moved to the operating position, such as Figure 2 When the manipulator 1 is moved away from the manipulating position, the thermal mass member 4 is thermally separated from the cooling unit 2 and the manipulator 1 can be moved substantially freely in order to process and / or hold the cryogenic sample 12 using the holder 3 .

[0045] like Figure 2 As shown in the figure, when the manipulator 1 is moved away from the cooling unit 2 and / or moved to the manipulating position or is in the manipulating position, the manipulator 1, in particular the holder 3 for the sample, is separated from the cooling unit 2. Therefore, because the manipulator 1 is not connected to the cooling unit 2 by a heat transfer member such as a braid, the manipulator 1 can move substantially freely. When the holder 3 is thermally separated from the cooling unit 2 (for example when processing the sample), due to the thermal mass member 4, the temperature increase of the holder 3 is at least reduced, preferably substantially prevented. Due to the thermal mass member 4, the braid for thermally connecting the holder 3 to the cooling unit 2 can be omitted.

[0046] Figure 1 and Figure 2Also schematically shown is an inspection system and / or focused ion beam system 10 having a sample holder 11. The system comprises a sample compartment 13, which is configured to substantially surround a sample 12. The components are at least partially arranged within the sample compartment 13.

[0047] exist Figure 1 and Figure 2 In the example shown in FIG, the cooling unit 2 is arranged against or in the wall 14 of the sample compartment 13. Figure 1 As shown in , the cooling unit 2 is arranged at a position in the sample compartment 13 so that the thermal mass member 4 may occasionally interface with the cooling unit 2 .

[0048] An example of an inspection system is an electron microscope. Such an electron microscope may be provided with a focused ion beam system for processing the sample 12. In case the inspection system is an electron microscope, the sample compartment 13 is preferably a vacuum chamber.

[0049] When using the assembly of the present invention, the method comprises the following steps:

[0050] The operating device 1 is arranged at Figure 1 a heat exchange position in which the thermal mass member 4 is in thermal contact with the cooling unit 2;

[0051] Cooling the thermal mass member 4 to a desired temperature or for at least a predetermined time; and

[0052] Move the operating device 1 from Figure 1 The hot swap position is moved to Figure 2 an operating position in which the thermal mass component 4 is thermally separated from the cooling unit 2.

[0053] Figure 3A and Figure 3B Various side views of a second example of an assembly according to the invention are schematically shown. The assembly comprises a manipulator 211 and a cooling unit 31. The cooling unit 31 comprises a first part 311 comprising a sample holding unit 29 and a second part 312 configured for cooling the thermal mass member 24 of the manipulator 211. Preferably, the sample holding unit 29 is an integral component of the cooling unit 31.

[0054] Likewise, the manipulator 211 includes a holder 23 for a sample and a thermal mass member 24 arranged in thermal contact with the holder 23. The manipulator 211 includes one or more actuators 25 for moving the holder 23, and an arm 26. The arm 26 is arranged between the one or more actuators 25 and the holder 23, and includes a heat insulating member that allows the holder 23 to be thermally isolated from the one or more actuators 25.

[0055] Figure 3A and Figure 3B Also schematically shown is an inspection system and / or focused ion beam system 30, which is configured for inspecting and / or processing a sample 32 on the sample holding unit 29. The system further comprises a sample compartment 33, which is configured to substantially surround the sample 32. The assembly is at least partially arranged inside the sample compartment 33. The cooling unit 31 is arranged at a position in the sample compartment 33 such that the thermal mass member 24 can occasionally be connected to the cooling unit 31, in particular to the second portion 312 thereof, as shown in FIG. Figure 3B as shown in .

[0056] Figure 4 A third example of an assembly according to the invention is schematically shown. Figure 4 The system shown in FIG. 1 is largely similar to that shown in FIG. Figure 1 and Figure 2 The same system as described in the first example. Figure 1 , Figure 2 and Figure 4 In the drawings, identical features are provided with the same reference numerals.

[0057] like Figure 4 The third embodiment shown in the figure differs from the first embodiment in that the thermal mass member 4 includes a chamber 42, which is at least partially filled with a phase change material, for example, isopentane. The phase change material can store a large amount of thermal energy during a phase change (such as from solid to liquid). Advantageously, a large amount of thermal energy can be stored at a relatively constant temperature when a phase change occurs. Therefore, the use of a phase change material in the chamber 42 of the thermal mass member 4 can provide temperature stabilization by storing a large amount of thermal energy without significantly changing the temperature.

[0058] As schematically shown, the chamber 42 preferably completely surrounds the phase change material, so that no phase change material can escape from the chamber 42 into the sample compartment 13 .

[0059] It should be understood that the above description is included to illustrate the operation of the preferred embodiment and is not meant to limit the scope of the invention. From the above discussion, many variations will be apparent to those skilled in the art, and these variations will also be covered by the scope of the invention.

Claims

1. An assembly comprising a manipulator and a cooling unit; It is characterized in that The manipulator comprises a holder for the sample and a thermal mass member arranged in thermal contact with the holder; the manipulation device is configured to place the manipulation device in a heat exchange position in which the thermal mass member is in thermal contact with the cooling unit, and the manipulation device is configured to move the manipulation device from the heat exchange position to a manipulation position in which the thermal mass member is thermally separated from the cooling unit; the thermal mass member includes a first heat transfer surface and the cooling unit includes a second heat transfer surface, wherein the first heat transfer surface and the second heat transfer surface are solid; The assembly is configured such that, in the heat exchange position, the first heat transfer surface is configured to abut against the second heat transfer surface such that the first heat transfer surface is arranged in thermal contact with the second heat transfer surface.

2. The assembly according to claim 1, characterized in that The thermal capacity of the thermal mass member is configured to substantially maintain a low temperature of the holder during manipulation of the sample at the manipulation position.

3. The assembly according to claim 1 or 2, characterized in that The manipulation device includes one or more actuators for moving the holder, and a thermal insulation member arranged between the one or more actuators and the holder.

4. The assembly according to claim 3, characterized in that The thermal mass member is disposed between the thermal insulation member and the retainer.

5. The assembly according to claim 1 or 2, characterized in that The thermal mass member includes a chamber at least partially filled with a phase change material, wherein the phase change material includes a phase change at a predetermined low temperature adapted to substantially prevent a change in morphology of the sample or material surrounding the sample.

6. The assembly according to claim 5, characterized in that The phase change material includes a phase that changes from solid to liquid at the predetermined low temperature.

7. The assembly according to claim 6, characterized in that Phase change materials involve a phase change at a temperature below the point at which ice changes form.

8. The assembly according to claim 5, characterized in that The chamber is configured to surround the phase change material.

9. The assembly according to claim 3, characterized in that The thermal mass member includes a chamber at least partially filled with a phase change material, wherein the phase change material includes a phase change at a predetermined low temperature suitable for substantially preventing a change in morphology of the sample or material surrounding the sample.

10. An inspection system and / or a focused ion beam system, characterized in that: The system comprises a sample compartment configured to substantially surround a sample, wherein the sample compartment comprises a component according to any one of claims 1-9, which component is at least partially arranged inside the sample compartment.

11. The inspection system and / or focused ion beam system according to claim 10, characterized in that: The cooling unit is arranged against or in a wall of the sample compartment.

12. The inspection system and / or focused ion beam system according to claim 10, characterized in that: The system comprises a sample holding unit, wherein the cooling unit is connected to the sample holding unit, or wherein the cooling unit is an integral part of the sample holding unit.

13. The inspection system and / or focused ion beam system according to claim 10, 11 or 12, characterized in that: The system includes an electron microscope.

14. The inspection system and / or focused ion beam system according to claim 13, characterized in that: The sample compartment includes a vacuum chamber.

15. The inspection system and / or focused ion beam system according to claim 10, 11 or 12, characterized in that: The sample compartment includes a vacuum chamber.

16. A method for using an assembly according to any one of claims 1 to 9, It is characterized in that The method comprises the following steps: placing the handling device in a heat exchange position in which the first heat transfer surface is configured to abut against the second heat transfer surface and the thermal mass member is in thermal contact with the cooling unit via at least the first heat transfer surface and the second heat transfer surface; and The operating device is moved from the heat exchange position to an operating position in which the thermal mass component is thermally decoupled from the cooling unit.

17. The method of claim 16, wherein when using the assembly, the thermal mass member comprises a chamber at least partially filled with a phase change material, wherein the phase change material comprises a phase change at a predetermined low temperature, the predetermined low temperature being suitable for substantially preventing a change in the morphology of the sample or a material surrounding the sample, characterized in that The method comprises the following steps: The second heat transfer surface is cooled to a temperature at or below the predetermined low temperature.

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