Valve for charged-particle beam microscope, valve member, and charged-particle beam microscope

Abstract

To provide a valve for a charged-particle beam microscope, a valve member, and a charged-particle beam.SOLUTION: According to an embodiment, a valve (65) for a charged-particle beam microscope is provided. The valve comprises: a valve seat (12) having an open (11); and a valve member having a valve member main body (13) and a seal ring (14) on a first surface of the valve member main body (13). The valve member can be moved between a first position where the seal ring (14) seals a circumference of the open (11) and a second position where the valve member is separated from the open (11). The valve member further comprises an electrical conduction property shield member (15) that is extended to at least side part front surface of the valve member main body (13) that is directed to the open (11) at the second position.SELECTED DRAWING: Figure 1A-1D

Description

[Technical field]

[0001] (Priority) This application claims priority to DE 10 2023 118 986.7, the disclosure of which is incorporated herein by reference.

[0002] The present application relates to a valve for a charged particle beam microscope, a valve member of such a valve, and a corresponding charged particle beam microscope. [Background technology]

[0003] A charged particle beam microscope is a type of microscope in which a charged particle beam, e.g. an electron beam or an ion beam, is directed to a sample and the interaction between the charged particle beam and the sample is used to generate an image. Examples for charged particle beam microscopes are the transmission electron microscope (TEM) and the scanning electron microscope (SEM). To increase the throughput, such microscopes may also use two or more charged particle beams, e.g. in the so-called multi-beam SEM (MSEM: Multi-SEM).

[0004] In general, such a charged particle beam microscope includes a charged particle beam source for generating a charged particle beam, a component, e.g., a magnet, for focusing the charged particle beam onto a sample, and one or more detectors for detecting a response, which may include, for example, a reflected charged particle beam, a scattered charged particle beam, secondary charged particles such as Auger electrons, or also other types of radiation such as generated x-ray radiation.

[0005] In most types of charged particle beam microscopes, the charged particle beam is directed onto the sample, at least in most cases, through a vacuum. In charged particle beam sources, ultra-high vacuum (UHV) is usually used (1×10 -9mbar), while in other parts the beam is in high vacuum (e.g. 1×10 -6 mbar) and then high vacuum (e.g., 1×10 -6 A pressure of 1000 psi (2000 psi, 1000 psi, or more) is sufficient. A valve is used in some configurations to separate a first section, where the charged particle beam is generated, from a second chamber, where the sample resides. As an example, FIG. 6 shows a columnar arrangement of a charged particle beam microscope 60, including an upper chamber 61 and a lower chamber 62. As indicated by the arrows, both the upper chamber 61 and the lower chamber 62 can be evacuated to create a vacuum therein.

[0006] The upper chamber 61 contains a cathode 63 that generates a charged particle beam, e.g., electrons. The charged particle beam exits the upper stage 61 and enters the lower stage 62 via a channel (pressure stage) 64. The pressure in the lower stage 62 is higher than that in the upper stage 61 (e.g., UHV in the upper stage 61 and high vacuum in the lower stage 62), as discussed above.

[0007] The charged particle beam is focused onto a sample 68 via an objective lens 67. A detector 66 serves to detect signals, e.g. scattered particles, secondary particles and / or radiation, as mentioned above. Around the detector 66 the pressure may again be higher than in the lower stage 62, e.g. 1×10 -5 It should be noted that the pressures herein are given by way of example only and may vary depending on the embodiment.

[0008] A valve 65 is provided and may be used to isolate upper chamber 61 from lower chamber 62. For example, if vacuum is lost in lower chamber 62, valve 65 may be closed to maintain the vacuum in upper chamber 61 and protect cathode 63. Similarly, valve 65 may be closed when the charged particle beam microscope is not in use or if the sample becomes charged.

[0009] The present application generally relates to such valves that may be used in a charged particle beam microscope to separate areas, e.g., upper chamber 61 and lower chamber 62 of Figure 6, from each other in an airtight manner. The other parts of such a charged particle beam microscope may be implemented in any conventional manner, Figure 6 only shows a simple, non-limiting example.

[0010] 5A and 5B show, for comparison, schematic side views of a conventional valve used in such a charged particle beam microscope. FIG. 5A shows the valve in an open position, and FIG. 5B shows the valve in a closed position. The valve shown in FIGS. 5A and 5B includes a valve seat 12 having an opening 11. In operation, a charged particle beam 16, e.g., an electron beam, passes through the opening 11 between the chambers mentioned above. In addition, the valve includes a valve member having a valve member body 13 and a sealing ring 14, such as an O-ring, on a first surface of the valve member body 13. In the open position, the valve member body 13 is retracted such that the opening 11 is open. In the closed position, the valve member body 13 presses the sealing ring 14 against the outer periphery of the opening 11, thus sealing the opening.

[0011] An electrical contact spring (not shown) is provided on a side surface of the valve member body 13. In the closed position, the electrical contact spring, which is electrically conductive, is in electrical contact with the valve seat 12, and in the open position, the electrical contact spring is in electrical contact with a portion, sometimes called the "valve garage", generally referred to herein as the valve housing member, which provides a type of housing for the valve member. This serves to bring the valve member to a particular potential, e.g., ground, in the closed position, or to an accelerating voltage for a charged particle beam, e.g., in the kilovolt range, in the open position.

[0012] However, this electrical contact spring may deteriorate over time, for example, by corrosion and / or mechanical wear, resulting in an undefined potential of the valve member. Furthermore, in the open position shown in FIG. 5A, the sealing ring 14 may become charged by the charged particle beam 16. Such an effect may result in a certain deflection of the charged particle beam 16, which may degrade the image quality or result in an unstable image position, i.e., image drift. Furthermore, the electrical contact spring may, for example, corrode. Furthermore, particles may be generated by the movement and moving contact between the electrical contact spring and the valve seat 12 or the housing, respectively. Summary of the Invention

[0013] According to a first aspect, there is provided a valve for a charged particle beam microscope, the valve comprising: a valve seat having an opening; a valve member comprising a valve member body and a sealing ring on a first surface of the valve member body, the valve member being movable between a first position in which the sealing ring seals around the opening and a second position in which the valve member is spaced from the opening; The valve member further includes an electrically conductive shielding member extending over at least a side surface of the valve member body facing the opening in the second position.

[0014] In some embodiments, the shielding member may prevent charging of the sealing ring in the second position.

[0015] The second position may be offset from the first position in a direction parallel to the plane in which the aperture is disposed.The shielding member may be made, for example, from a metal.

[0016] The shielding member may extend above the first surface in the second position to a height at least corresponding to a height of the sealing ring, in some embodiments this may provide good shielding of the sealing ring.

[0017] The sealing ring may for example be an O-ring made of a rubber material.

[0018] The shielding member may be attached to a second surface of the valve member body opposite the first surface, in some embodiments this may provide some robustness to the placement of the shielding member coupled to the valve member body.

[0019] The valve may further include a valve housing member extending below the valve member. In such an embodiment, the shielding member may be configured to be in electrical contact with at least a conductive portion of the valve housing member in the second position. This may enable biasing of the valve member in the second position by the valve housing member and the shielding member. For example, the valve housing member may be configured to be set to a high voltage potential when the valve member is at least in the second position, such that the valve member is biased at the high voltage potential in the second position by the shielding member.

[0020] Further, the shielding member may be configured to be in electrical contact with a conductive portion of the valve seat when the valve member is in the first position, such that in the first position the valve member may be biased, for example, to ground potential via the valve seat if the valve seat is configured to be set to ground potential at least when the valve is in the first position.

[0021] Additionally, the valve member may include an electrical contact spring on a further side surface of the valve member, the electrical contact spring configured to receive a first voltage in a first position and a second voltage in a second position, e.g., the high voltage and ground potentials mentioned above, The first voltage may be a high voltage and the second voltage may correspond to ground.

[0022] The valve seat may include a further shielding member about the opening, the sealing ring being configured to abut the further shielding member in the first position and to be shielded by the further shielding member in the second position, which may provide further shielding for the sealing ring in some embodiments.

[0023] This further shielding member may likewise be used independently of the shielding member, whereby in a second embodiment there is provided a valve for a charged particle beam microscope, the valve comprising a valve seat comprising an aperture and a shielding member around the aperture; The valve member includes a valve member body and a sealing ring on a first surface of the valve member body, the valve member being movable between a first position in which the sealing ring abuts the shielding member to seal around the opening and a second position in which the valve member is spaced from the opening, the sealing ring being shielded by the shielding member.

[0024] The valve may further comprise a flexible electrically conductive wire coupled to the valve member body, by which the valve member may be biased, for example, to the first and / or second voltages mentioned above. This may likewise be used independently or in combination with the above features, whereby in a third aspect there is provided a valve for a charged particle beam microscope, the valve comprising: a valve seat having an opening; A valve member comprising a valve member body and a sealing ring on a first surface of the valve member body, the valve member being movable between a first position in which the sealing ring seals around the opening and a second position in which the valve member is spaced from the opening, and a flexible electrically conductive member attached to the electrically conductive member attached to the valve member body for biasing the valve member.

[0025] Further, an electrical contact may be provided adjacent the valve seat such that the valve member contacts the electrical contact in the second position. This serves similarly to bias the valve member in the second position and may be used independently of some of the above features. In this respect, the electrical contact may form part of a recess in which the valve member is positioned when in the second position. Thus, according to a fourth aspect, there is provided a valve for a charged particle beam microscope, the valve comprising a valve seat with an opening, an electrical contact adjacent the valve seat, and a valve member comprising a valve member body and a sealing ring on a first surface of the valve member body, the valve member being movable between a first position in which the sealing ring seals around the opening and a second position in which the valve member is spaced from the opening and contacts the electrical contact.

[0026] To reduce friction and particle generation due to friction, a suitable vacuum compatible lubricant may be provided where the valve member is in sliding contact with other parts, such as the valve housing member. For example, a lubricant may be provided where the shielding member makes electrical contact with the conductive part of the valve housing member, or where the electrical contact spring of the further side surface makes contact with other elements. The lubricant may be based on fluoropolymers or silicone grease. The lubricant may be highly inert, i.e. not prone to chemical reactions, and therefore may protect against corrosion in some embodiments. For example, a suitable lubricant may have a viscosity of 250-300 mm at 20°C. 2 The viscosity may be on the order of 100000 / sec for 2 min at 200 °C, based on polyfluoroethylene (PFE) with a TOC (out-of-gas) value of 20 ng / mg or less when analyzed by GC-MS (gas chromatography combined with mass spectrometry).

[0027] This may be independent of the above, so that according to a fifth aspect: A valve for a charged particle beam microscope is provided, the valve comprising: a valve seat having an opening; a valve member comprising a valve member body and a sealing ring on a first surface of the valve member body, the valve member being movable between a first position in which the sealing ring seals around the opening and a second position in which the valve member is spaced from the opening; and a lubricant at at least one sliding contact point between the valve member and the further portion of the valve.

[0028] According to a further aspect, there is provided a corresponding valve member.According to a further aspect, there is provided a charged particle beam microscope comprising any of the valves discussed above.

[0029] Various embodiments are described with reference to the accompanying drawings. [Brief description of the drawings]

[0030] [Figure 1A-1D] 2A-2D are various views of a valve and valve member according to an embodiment; [Fig. 1E-1F] 2A-2D are various views of a valve and valve member according to an embodiment; [Figure 2A-2B] FIG. 13 is a side view of a valve and valve member according to a further embodiment. [Figure 3A-3B] FIG. 13 is a side view of a valve and valve member according to a further embodiment. [Figure 4A-4B] FIG. 13 is a diagram of a valve illustrating the use of a lubricant according to some embodiments. [Figure 5A-5B] FIG. 13 is a diagram of a valve according to a comparative example. [Figure 6] FIG. 1 is a schematic diagram of a charged particle beam microscope. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] In the following, various embodiments of valves and valve members for charged particle beam microscopes are discussed. The discussed valves and valve members may in particular separate a first chamber in which a charged particle beam, such as an electron beam, is generated from a second chamber in which a sample is provided, for example to maintain a vacuum. As an example, the discussed valves may be used as valve 65 in the charged particle beam microscope of FIG. 6 described above.

[0032] Features from different embodiments may be combined to form further embodiments. For example, different embodiments may include different modifications compared to the comparative examples discussed in the introductory section regarding Figures 5A and 5B, and these modifications may be used independently or in various combinations with each other. Meanwhile, in a single embodiment shown in the figures and described herein, two or more such modifications may be present, and similarly in this case the modifications may be used independently or in combination with each other.

[0033] In the figures, similar components are designated with the same reference numerals and will not be described repeatedly.

[0034] Figure 1A is a side view of a valve according to one embodiment in an open position, and Figure 1B is a side view of the valve of Figure 1A in a closed position. Figures 1E and 1F show perspective views of an example implementation of the valve of Figures 1A and 1B.

[0035] 1A and 1B includes a valve seat 12 having an opening 11. In operation, a charged particle beam 16, for example an electron beam, passes through the opening 11.

[0036] The valve includes a valve member body 13, a sealing ring 14 disposed on a first face of the valve member body 13, and a shielding member 15. As can be seen in Figure 1B, in the closed position (also referred to herein as the first position), the sealing ring 14 seals around the opening 11, for example, to prevent vacuum loss.

[0037] Shielding member 15 is made of an electrically conductive material, such as a metal or metal alloy, and extends on a face of valve member body 13 facing opening 11 and charged particle beam 16 in the open position of the valve member of Figure 1A (also referred to herein as the second position). Shielding member 15 extends above the first surface such that sealing ring 14 is shielded from charged particle beam 16, and shielding member 15 may, in some embodiments, prevent charging of sealing ring 14.

[0038] 1A and 1B, the shielding member 15 may be attached to a second face of the valve member body 13 opposite the first face (on which the sealing ring 14 is provided) so as to be secured in a spring-like manner. In the closed position of FIG. 1B, as shown, the shielding member 15 then abuts the valve seat 12 and establishes electrical contact thereto. The valve seat 12 in the closed position may be set to, for example, ground potential, and this contact between the shielding member 15 and the valve seat 12 contributes to setting the valve member at ground potential as well.

[0039] As in conventional systems, the valve may include a valve housing member 17 that extends below the valve member in the figures, as shown in Figures 1C and 1D. Also in this case, in the closed position, the shielding member 15 abuts the valve seat 12, as shown in Figure 1C.

[0040] Additionally, in some embodiments, as shown in Figure ID, in the open position, the shielding member 15 may press against the valve housing member 17, such that in the open position, the shielding member 15 may be biased, for example, to a high voltage potential by the valve housing member 17. In other embodiments, in the open position, the shielding member 15 is not in contact with the valve housing member 17 in the open position.

[0041] Additionally, the valve member of Figures 1E and 1F has an electrical spring contact 18 on the side of the valve member, which in the embodiment of Figures 1E and 1F is integrally formed with the shielding member 15. In other embodiments, an embodiment using a separate piece or element for the shielding member 15 may be used. The electrical spring contact 18 serves to provide further conventional contact for biasing the valve member, as described in the introduction with respect to Figures 5A and 5B, see electrical spring contact 18. In this case, the biasing by the shielding member 15 shown in Figures 1B, 1C for contact against the valve seat, and in Figure 1D for contact against the valve housing member 17, provides further contact by the electrical spring contact 18 for the conventional contact.

[0042] Figures 2A and 2B show a valve according to a further embodiment, with Figure 2A showing the open case in which the valve member is in a second position and Figure 2B showing the closed case in which the opening 11 is sealed.

[0043] Instead of the shielding element 15 provided in the embodiment of Figures 1A-1F, here a further shielding element 21 is provided which extends from the valve seat 12 and surrounds the opening 11. In the position shown in Figure 2A, the further shielding element 21 is inserted between the sealing ring 14 and the charged particle beam 16, whereby charging of the sealing ring 14 is prevented or at least reduced. In a first state, shown in Figure 2B, the sealing ring 14 abuts against the further shielding element 21 and thus seals the opening 11.

[0044] In some embodiments, an additional shielding member 21 may be combined with the shielding member 15 discussed above.

[0045] 2A and 2B, an electrically conductive member 20 is attached to the valve member body 13. Using the electrically conductive member 20, the valve member can be reliably biased to a high voltage or to ground in some embodiments. In some embodiments, the electrically conductive member 20 can be a flexible member such as a wire or a cable such as a ribbon cable. In other embodiments, the electrically conductive member 20 can be completely or partially rigid, for example with flexible or rolling contacts remote from the valve member.

[0046] Figures 3A and 3B show a valve according to a further embodiment, with Figure 3A showing the second position (open position) and Figure 3B showing the first position (closed position).

[0047] Here, in the open case of Fig. 3A, a valve seat 32 is provided having a recess 31 in which the sealing ring 14 is positioned, whereby the sealing ring 14 is shielded from the charged particle beam 16. Furthermore, an electrically conductive element 33 is provided, against which the valve member body 13 abuts in the second position, thus providing an electrical contact for biasing the valve member. It should be noted that in the embodiment of Figs. 3A and 3B, a shielding element 15 is provided and has the function described with reference to Figs. 1A-1F, in particular in the first position of Fig. 3B, in which the sealing ring 14 is pressed against the valve seat 32, abutting against the valve seat 32 to seal around the opening 11. Nevertheless, the recess and the electrical contact element 33 of Figs. 3A and 3B may be provided independently of the shielding element 15.

[0048] In a further embodiment, together with or independent of the embodiments discussed above, a lubricant is used at the point where the sliding electrical contact is established. This is shown in Figures 4A and 4B. Figure 4A reproduces Figure 1D. Reference numeral 40 indicates the location where the shielding member 15 makes sliding contact with the valve housing member 17, which may correspond to the contact established by the protrusion 19, as shown in Figures 1H and 1J. Figure 4B shows a top view where the electric spring contact 18 makes contact with the valve housing member 17 or any other point, where a lubricant may be used as well, as shown by reference numeral 41. The lubricant may protect against mechanical wear and particle generation. Such wear, in addition to problems that may be generated by free particles within the charged particle beam microscope itself, may increase the surface of the electric spring contact 18 or the corresponding contact element, such as the shielding member 15, which may in turn increase oxidation or other chemical reactions, which may reduce the quality of the electrical contact. For example, the shielding member 15 may be made of copper, bronze, or brass (such as chrome-plated brass), and in a charged particle beam microscope, NOCl gas may react with such metals to form copper chloride, which may provide electrical insulation. Such NOCl gas is used as a process gas to locally etch structures in the sample by the electron beam, but may also inadvertently react with other components in the device.

[0049] Suitable lubricants include fluoropolymer or silicone grease-based lubricants such as the so-called TEM oils. Examples include APIEZON® high vacuum grease or silicone high vacuum grease by Plano GmbH or Lit-Oil 300 or 500 oils from the Zeiss materials catalogue.

[0050] Thus, various embodiments herein may increase the reliability of biasing of the valve member and / or provide a shield for the sealing ring, which in some embodiments may prevent or mitigate image quality degradation or image position drift in a charged particle beam microscope.

[0051] Although specific embodiments have been shown and described herein, it will be recognized by those skilled in the art that various alternative and / or equivalent implementations may be substituted for the specific embodiments shown and described without departing from the scope of the invention. This application is intended to cover any adaptations or variations of the specific embodiments discussed herein. It is therefore intended that the invention be limited only by the claims and the equivalents thereof. [Explanation of symbols]

[0052] 11 Aperture 12, 32 Valve seat 13 Valve member body 14 Sealing ring 15 Shielding materials 16 Charged Particle Beam 17 Valve housing member 18 Electrical spring contacts 19 Protrusion 20 Electrically conductive materials 21 Shielding 31 Recess 33 Electrical contact elements 40, 41 Sliding contact points 60 Charged Particle Beam Microscope 61 Upper chamber 62 Lower Chamber 63 Cathode 64 channels 65 Valve 66 Detector 67 Objective Lens 68 Samples

Claims

1. A valve (65) for a charged particle beam microscope (60), comprising: a valve seat (12, 32) having an opening (11); a valve member comprising a valve member body (13) and a sealing ring (14) on a first surface of the valve member body (13), the valve member being movable between a first position in which the sealing ring (14) seals around the opening (11) and a second position in which the valve member is spaced from the opening (11); The valve member further comprises an electrically conductive shielding member (15) extending over at least a side surface of the valve member body (13) facing the opening (11) in the second position.

2. 2. The valve (65) of claim 1, wherein the shielding member (15) in the second position extends above the first surface of the valve member body (13) to a height that corresponds at least to a height of the sealing ring (14).

3. 3. A valve (65) as claimed in claim 1 or 2, wherein the shielding member (15) is attached to a second surface of the valve member body (13) opposite the first surface.

4. 4. The valve (65) of claim 3, further comprising a valve housing member (17) extending below the valve member, the shielding member (15) being configured to make electrical contact with a conductive portion of the valve housing member (17) in the second position.

5. 5. The valve (65) of claim 4, wherein the conductive portion of the valve housing member (17) is configured to be set to a first electrical potential when the valve member is at least in the second position.

6. The valve (65) of any one of claims 1 to 5, wherein the shielding member (15) is configured to be in electrical contact with a conductive portion of the valve seat (12) when the valve member is in the first position.

7. 7. The valve (65) of claim 6, wherein the conductive portion of the valve seat (12) is configured to be set to a second electrical potential when the valve member is at least in the first position.

8. A valve (65) as claimed in any one of claims 1 to 7, wherein the valve member comprises an electrical contact spring (18) on a further side surface of the valve member, the electrical contact spring (18) being configured to receive a first voltage in the first position and a second voltage in the second position.

9. The valve (65) of any one of claims 1 to 8, wherein the valve seat (12) is provided with a further shielding member (21) around the opening, and the sealing ring (14) is configured to abut against the further shielding member (21) in the first position and to be shielded by the further shielding member (21) in the second position.

10. A valve (65) according to any preceding claim, wherein the valve member further comprises a flexible, electrically conductive wire attached to the valve member body (13) and configured for biasing the valve member.

11. A valve (65) according to any preceding claim, comprising an electrical contact (33) configured to contact the valve member body (13) at the first surface for biasing it in the second position.

12. A valve (65) according to any one of the preceding claims, wherein the valve seat (12, 32) comprises a recess (31) for accommodating at least the sealing ring (14) in the second position.

13. A valve (65) according to any one of the preceding claims, further comprising a lubricant in at least one sliding contact point (40, 41) between the valve member and the further part of the valve.

14. The valve (65) of claim 13, wherein the lubricant comprises a fluoropolymer.

15. A valve (65) for a charged particle beam microscope, comprising: a valve seat (12, 32) having an opening (11) and a shielding member (21) around said opening (11); a valve member comprising a valve member body (13) and a sealing ring (14) on a first surface of the valve member body (13), the valve member being movable between a first position in which the sealing ring (14) abuts the shielding member (21) to seal the opening (11) and a second position in which the valve member is spaced from the opening (11) and the sealing ring (14) is sealed by the shielding member (21); The valve member further comprises an electrically conductive shielding member (15) extending over at least a side surface of the valve member body (13) facing the opening (11) in the second position.

16. A valve (65) for a charged particle beam microscope, comprising: a valve seat (12, 32) having an opening (11); a valve member comprising a valve member body (13) and a sealing ring (14) on a first surface of the valve member body (13), the valve member being movable between a first position in which the sealing ring (14) seals around the opening (11) and a second position in which the valve member is spaced from the opening (11); A lubricant at at least one sliding contact point (40, 41) between said valve member and said further part of the valve (65).

17. A valve (65) for a charged particle beam microscope (60), comprising: a valve seat (12, 32) having an opening (11); a valve member comprising a valve member body (13) and a sealing ring (14) on a first surface of the valve member body (13), the valve member being movable between a first position in which the sealing ring (14) seals around the opening (11) and a second position in which the valve member is spaced from the opening (11); A valve (65), wherein the valve seat (12, 32) comprises a recess (31) for accommodating at least the sealing ring (14) in the second position.

18. A valve (65) for a charged particle beam microscope, comprising: a valve seat (12, 32) having an opening (11); a valve member comprising a valve member body (13) and a sealing ring (14) on a first surface of the valve member body (13), the valve member being movable between a first position in which the sealing ring (14) seals around the opening (11) and a second position in which the valve member is spaced from the opening (11); an electrical contact (33) configured to contact the valve member body (13) at the first surface for biasing it in the second position.

19. A valve member for a valve (65) of a charged particle beam microscope (60), comprising: A valve member body (13); a sealing ring (14) on a first surface of the valve member body (13); an electrically conductive shielding member (15) extending over at least a side surface of the valve member body (13) and extending above the first surface to a height greater than the sealing ring (14).

20. A valve member for a valve (65) of a charged particle beam microscope (60), comprising: A valve member body (13); a sealing ring (14) on a first surface of the valve member body (13); an electrically conductive member attached to the valve member body (13) and configured for biasing the valve member.

21. A charged particle beam microscope comprising a valve (65) according to any one of claims 1 to 18 or a valve (65) comprising a valve member according to claim 19 or 20.

Images