Valves, valve members, and charged particle beam microscopes

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 the priority of German Patent Application Publication No. 10 2023 118 986.7, the disclosure of which is incorporated herein by reference.

[0002] This 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 Art

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

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

[0005] In most types of charged particle beam microscopes, the charged particle beam is guided onto the sample through a vacuum, at least in most cases. In the charged particle beam source, usually ultra-high vacuum (UHV) is used (1×10 -9(above mbar) On the other hand, in other parts, the beam is in a high vacuum (e.g., 1 × 10⁻⁶ mbar). -6 It passes through a high vacuum (e.g., 1 × 10 mbar or higher) and a high vacuum (e.g., 1 × 10⁻¹⁰ mbar or higher). -6 A pressure of mbar or higher is sufficient. In some configurations, a valve is used to separate the first portion from which the charged particle beam is generated from the second chamber in which the sample is located. As an example, Figure 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 inside.

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

[0007] The charged particle beam is focused onto the sample 68 via the objective lens 67. The detector 66, as described above, helps to detect signals, such as scattered particles, secondary particles, and / or radiation. Around the detector 66, the pressure may again be higher than in the case of the lower stage 62, for example, 1 × 10⁻⁶ -5 It is less than or equal to mbar. It should be noted that the pressures herein are given merely as examples and may vary depending on the embodiment.

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

[0009] This application relates to a valve that can be used in a charged particle beam microscope to separate areas, for example, the upper chamber 61 and the lower chamber 62 in Figure 6, from each other in an airtight manner. Other parts of such a charged particle beam microscope can be carried out in any conventional way, and Figure 6 shows only a simple, non-limiting example.

[0010] Figures 5A and 5B show, for comparison, a conventional valve used in such a charged particle beam microscope in a schematic side view. Figure 5A shows the valve in the open position, and Figure 5B shows the valve in the closed position. The valves shown in Figures 5A and 5B include a valve seat 12 having an opening 11. When in operation, a charged particle beam 16, such as an electron beam, passes through the opening 11 between the chambers described above. Furthermore, 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 so that the opening 11 is open. In the closed position, the valve member body 13 presses the sealing ring 14 against the outer circumference of the opening 11, and thus seals the opening.

[0011] An electrical contact spring (not shown) is provided on the side surface of the valve member body 13. In the closed position, the electrically conductive electrical contact spring 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 a “valve garage,” and commonly referred herein as a valve housing member, which provides a kind of housing for the valve member. This helps to bring the valve member to a specific potential, for example to ground, in the closed position, or to an accelerating voltage for a charged particle beam in the kilovolt range, for example, in the open position.

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

[0013] According to a first embodiment, a valve for a charged particle beam microscope is provided, the valve is, A valve seat having an opening, The valve member comprises a valve member body and a valve member having a sealing ring on a first surface of the valve member body, wherein the valve member is movable between a first position in which the sealing ring seals around the opening and a second position in which the valve member is separated from the opening. The valve member further comprises an electrically conductive shielding member extending from at least the lateral surface of the valve member body facing the opening at the second position.

[0014] In some embodiments, the shielding member may prevent the sealing ring from becoming charged at the second position.

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

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

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

[0018] The shielding member may be attached to a second surface of the valve member body opposite to the first surface. In some embodiments, this may provide some degree of resilience to the arrangement of the shielding member coupled to the valve member body.

[0019] The valve may further comprise a valve housing member extending below the valve member. In such embodiments, the shielding member may be configured to electrically contact at least a conductive portion of the valve housing member at a second position. This may allow the valve housing member and the shielding member to bising the valve member at the second position. 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, thereby the valve member being bising at a high voltage potential at the second position by the shielding member.

[0020] Furthermore, the shielding member may be configured to electrically contact the conductive portion of the valve seat when the valve member is in the first position. Thus, if the valve is configured to set the valve seat to ground potential when the valve is at least in the first position, then in the first position, the valve member can be biased to ground potential, for example, via the valve seat.

[0021] Furthermore, the valve member may include an electrical contact spring on an additional lateral surface of the valve member, the electrical contact spring configured to receive a first voltage at a first position and a second voltage at a second position, such as the high voltage and ground potential described above. The first voltage may be a high voltage, and the second voltage may correspond to ground.

[0022] The valve seat may include an additional shielding member around the opening, and the sealing ring is configured to contact the additional shielding member at a first position and be shielded by the additional shielding member at a second position. In some embodiments, this additional shielding member may provide additional shielding for the sealing ring.

[0023] This additional shielding member may similarly be used independently of the shielding member, whereby, in a second aspect, a valve for a charged particle beam microscope is provided, the valve comprising a valve seat having an opening and a shielding member around the opening. The valve member comprises 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 where the sealing ring contacts the shielding member to seal around the opening and a second position where the valve member is spaced apart from the opening, and 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 described above. This may similarly be used independently of or in combination with the above features, whereby, in a third 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 where the sealing ring seals around the opening and a second position where the valve member is spaced apart from the opening, and an electrically conductive flexible electrically conductive wire attached to the valve member body for biasing the valve member.

[0025] Furthermore, the electrical contact may be provided adjacent to the valve seat such that the valve member contacts the electrical contact in the second position. This serves equally well to bias the valve member in the second position and may be used equally independently of some of the above features. In this regard, 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, a valve for a charged particle beam microscope is provided, the valve comprising a valve seat with an aperture, an electrical contact adjacent to 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 aperture and a second position in which the valve member is spaced from the aperture and contacts the electrical contact.

[0026] To reduce friction and particle generation due to friction, a suitable vacuum-compatible lubricant may be provided at the parts where the valve member makes a sliding contact with other parts such as the valve housing member. For example, the 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 on the further side surface contacts other elements. The lubricant may be based on a fluoropolymer or silicone grease. The lubricant may be very inert, i.e., may not tend to cause chemical reactions and thus, in some embodiments, may protect against corrosion. For example, a suitable lubricant may be polyfluoroethylene (PFE) having a viscosity on the order of 250 - 300 mm 2 / s at 20°C and having a TOC (total organic carbon) value of 20 ng / mg or less when analyzed by GC-MS (combining gas chromatography and mass spectrometry) at 200°C for 2 minutes.

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

[0028] In a further embodiment, a corresponding valve member is provided. In a further embodiment, a charged particle beam microscope is provided that comprises any of the valves discussed above.

[0029] Various embodiments will be described with reference to the accompanying drawings. [Brief explanation of the drawing]

[0030] [Figure 1A-1D] These are various diagrams of valves and valve members according to embodiments. [Figure 1E-1F] These are various diagrams of valves and valve members according to embodiments. [Figure 2A-2B] This is a side view of a valve and valve member according to a further embodiment. [Figure 3A-3B] This is a side view of a valve and valve member according to a further embodiment. [Figure 4A-4B] This is a diagram of a valve showing the use of a lubricant according to several embodiments. [Figure 5A-5B] This is a diagram of a valve in comparison to a previous example. [Figure 6] This is a schematic diagram of a charged particle beam microscope. [Modes for carrying out the invention]

[0031] Various embodiments of valves and valve members for charged particle beam microscopes are discussed below. The valves and valve members discussed may, for example, specifically separate a first chamber from which a charged particle beam, such as an electron beam, is generated, from a second chamber in which a sample is placed, in order to maintain a vacuum. As an example, the valve discussed may be used as valve 65 in the charged particle beam microscope shown in Figure 6 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 introduction relating to Figures 5A and 5B, and these variations may be used independently or in various combinations with each other. On the other hand, in a single embodiment shown in the figures and described herein, there may be two or more such variations, and similarly in this case, the variations may be used independently or in combination with each other.

[0033] In the diagram, similar components will be specified with the same reference number and will not be described repeatedly.

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

[0035] The valve in Figures 1A and 1B includes a valve seat 12 having an opening 11. During operation, a charged particle beam 16, such as 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 surface 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] The shielding member 15 is made of an electrically conductive material, such as a metal or metal alloy, and extends onto the surface of the valve member body 13 facing the opening 11 and the charged particle beam 16 in the open position of the valve member in Figure 1A (also referred to herein as the second position). The shielding member 15 extends above the first surface so that the sealing ring 14 is shielded from the charged particle beam 16, and in some embodiments, the shielding member 15 may prevent the sealing ring 14 from becoming charged.

[0038] As can be seen in Figures 1A and 1B, the shielding member 15 may be attached to a second surface of the valve member body 13 opposite to the first surface (where the sealing ring 14 is provided) so as to be secured in a spring-like manner. In the closed position shown in Figure 1B, the shielding member 15 then contacts the valve seat 12, establishing electrical contact with the valve seat 12. In the closed position, the valve seat 12 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 to ground potential as well.

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

[0040] Furthermore, in some embodiments, as shown in Figure 1D, the shielding member 15 may press against the valve housing member 17 in the open position, thereby allowing the shielding member 15 to be biased, for example, to a high voltage potential by the valve housing member 17 in the open position. In other embodiments, the shielding member 15 is not in contact with the valve housing member 17 in the open position.

[0041] Furthermore, the valve members in Figures 1E and 1F have electric spring contacts 18 on the side surface of the valve member, and in the embodiments of Figures 1E and 1F, the electric spring contacts 18 are integrally formed with the shielding member 15. In other embodiments, embodiments may be used in which a separate piece or element is used for the shielding member 15. See electric spring contact 18, which helps to provide further conventional contact for biasing the valve member, as described in the introduction with respect to Figures 5A and 5B. In this case, the biasing by the shielding member 15, shown in Figures 1B and 1C for contact with the valve seat, and in Figure 1D for contact with the valve housing member 17, provides further contact by the electric spring contact 18 to the conventional contact.

[0042] Figures 2A and 2B show valves according to further embodiments, where Figure 2A shows the open case with the valve member in a second position, and Figure 2B shows the closed case with the opening 11 sealed.

[0043] Instead of the shielding member 15 provided in the embodiments of Figures 1A to 1F, a further shielding member 21 is provided here, extending from the valve seat 12 and surrounding the opening 11. In the position shown in Figure 2A, the further shielding member 21 is inserted between the sealing ring 14 and the charged particle beam 16, thereby preventing or at least reducing the charging of the sealing ring 14. In the first state shown in Figure 2B, the sealing ring 14 abuts against the further shielding member 21 and thus seals the opening 11.

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

[0045] Furthermore, in the embodiments shown in Figures 2A and 2B, the 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 may be a flexible member such as a wire or a cable such as a ribbon cable. In other embodiments, the electrically conductive member 20 may be entirely or partially rigid and have, for example, a flexible contact or rolling contact at a distance from the valve member.

[0046] Figures 3A and 3B show valves according to further embodiments. Figure 3A shows a second position (open position), and Figure 3B shows a first position (closed position).

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

[0048] In further embodiments, either in conjunction with or independently of the embodiments discussed above, a lubricant is used at the point where sliding electrical contact is established. This is shown in Figures 4A and 4B. Figure 4A replicates 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 a contact established by the projection 19, as shown in Figures 1H and 1J. Figure 4B shows a top view where the electric spring contact 18 contacts the valve housing member 17 or any other point, and here again, a lubricant may be used, as indicated by reference numeral 41. The lubricant may protect against mechanical wear and particle generation. Such wear, in addition to the problem that can be generated by free particles within the charged particle beam microscope itself, may increase the surface area of ​​the corresponding contact element, such as the electric spring contact 18 or the shielding member 15, which may then increase oxidation or other chemical reactions, which may degrade 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, the NOCl gas may react with such metals to form copper chloride, which may provide electrical insulation. Such NOCl gas is used as a processing gas to locally etch structures in a sample by an electron beam, but it may also inadvertently react with other components in the device.

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

[0050] Accordingly, various embodiments of this specification may improve the reliability of the biasing of valve members and / or provide a shield for the sealing ring, which in some embodiments may prevent or reduce image quality degradation or image position drift in a charged particle beam microscope.

[0051] While specific embodiments are shown and described herein, it will be recognized by those skilled in the art that various alternative and / or equivalent embodiments can be substituted for the specific embodiments shown and described without departing from the scope of the invention. This application is intended to cover any adaptation or modification of the specific embodiments discussed herein. Accordingly, the invention is intended to be limited only by the claims and their equivalents. [Explanation of Symbols]

[0052] 11 Aperture 12, 32 valve seats 13 Valve component body 14 sealing rings 15 Shielding components 16 Charged particle beam 17 Valve housing member 18 Electric spring contacts 19 Protrusion 20 Electrically conductive members 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 valves 66 detectors 67 Objective lens 68 samples

Claims

1. A valve (65) for a charged particle beam microscope (60), A valve seat (12, 32) having an opening (11), The valve member comprises a valve member body (13) and a sealing ring (14) on a first surface of the valve member body (13), wherein the valve member is 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 separated from the opening (11). The valve member further comprises an electrically conductive shielding member (15) extending from at least the lateral surface of the valve member body (13) facing the opening (11) at the second position, in a valve (65).

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

3. The valve (65) according to claim 1 or 2, wherein the shielding member (15) is attached to the second surface of the valve member body (13) opposite to the first surface.

4. The valve (65) according to claim 3, further comprising a valve housing member (17) extending below the valve member, wherein the shielding member (15) is configured to electrically contact the conductive portion of the valve housing member (17) at the second position.

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

6. The valve (65) according to claim 1 or 2, wherein the shielding member (15) is configured to make electrical contact with the conductive portion of the valve seat (12) when the valve member is in the first position.

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

8. The valve member comprises an electrical contact spring (18) on a further side surface of the valve member, the electrical contact spring (18) configured to receive a first voltage at the first position and a second voltage at the second position, the valve (65) according to claim 1 or 2.

9. The valve (65) according to claim 1 or 2, wherein the valve seat (12) comprises 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. The valve (65) according to claim 1 or 2, wherein the valve member further comprises a flexible electrically conductive wire attached to the valve member body (13) and configured to bias the valve member.

11. The valve (65) according to claim 1 or 2, comprising an electrical contact (33) configured to contact the valve member body (13) on the first surface for biasing at the second position.

12. The valve seat (12, 32) is provided with a recess (31) for accommodating at least the sealing ring (14) at the second position, according to claim 1 or 2, the valve (65).

13. The valve (65) according to claim 1 or 2, further comprising a lubricant at at least one sliding contact point (40, 41) between the valve member and a further portion of the valve.

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

15. A valve (65) for a charged particle beam microscope, A valve seat (12, 32) having an opening (11) and a shielding member (21) around the opening (11), The valve member comprises a valve member body (13) and a sealing ring (14) on a first surface of the valve member body (13), wherein the valve member is movable between a first position in which the sealing ring (14) abuts against the shielding member (21) to seal the opening (11) and a second position in which the valve member is separated 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 from at least the lateral surface of the valve member body (13) facing the opening (11) at the second position, in a valve (65).

16. A charged particle beam microscope comprising the valve (65) described in claim 1.

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