High-frequency grounding device and vacuum valve equipped with high-frequency grounding device

Abstract

To provide an improved high-frequency grounding device for a vacuum valve of a vacuum chamber system, for avoiding undesired plasma discharges in the vacuum chamber system.SOLUTION: A high-frequency grounding device (40) for use with a vacuum valve has a grounding strap (42) having a first end (41) and a second end (43) made of a conductive material for discharging electrical charges occurring on the vacuum valve, where the first end is connected to a valve closure of the vacuum valve, and the second end is connected to a component of a vacuum chamber system. The high-frequency grounding device has a correction impedance, where the grounding strap is coupled to the correction impedance so that an oscillation circuit comprising the grounding strap and the correction impedance is formed, and the correction impedance has a first element for shifting a resonant frequency of the oscillation circuit and / or a second element for reducing the quality of the oscillation circuit.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to an improved high-frequency grounding device for a vacuum valve of a vacuum chamber system for avoiding unwanted plasma discharge in the vacuum chamber system. The present invention further relates to a vacuum valve provided with such a high-frequency grounding device, particularly a transfer vacuum valve, and a vacuum chamber system provided with such a vacuum valve.

[0002] Generally, valves are provided, particularly for making it possible to adjust the flow rate of a fluid. The flow can be made possible through the maximum valve opening cross-section or completely blocked by the valve. Further, certain valve types offer the possibility of adjusting the flow rate per unit time, i.e., offer the possibility of adjusting the fluid flow rate.

[0003] Vacuum valves form a special type of valve. Various embodiments of vacuum valves are known based on the prior art for adjusting the volume flow rate or the mass flow rate and / or for substantially gas-tightly closing the flow path through an opening formed in the valve housing, particularly for use in vacuum chamber systems in the field of IC manufacturing, semiconductor manufacturing, or substrate manufacturing, which must be carried out with the presence of contaminating particles minimized within a protected atmosphere.

[0004] Such a vacuum chamber system includes, in particular, at least one evacuable vacuum chamber provided for housing semiconductor elements or substrates to be supplied or manufactured, the vacuum chamber having at least one vacuum chamber opening through which semiconductor elements or other substrates can be moved in and out of the vacuum chamber. The vacuum chamber system further includes at least one vacuum pump for evacuating the vacuum chamber. For example, in a manufacturing facility for semiconductor wafers or liquid crystal substrates, highly sensitive semiconductor elements or liquid crystal elements pass through a plurality of process vacuum chambers in sequence, and within these process vacuum chambers, the components inside each process vacuum chamber are processed by a single processing device. During the processing process inside the process vacuum chambers and during transport from chamber to chamber, the highly sensitive semiconductor elements or substrates must always be in a protected atmosphere, particularly in a vacuum environment.

[0005] To this end, peripheral valves are used to open and close the gas supply or gas discharge section, and other transfer valves are used to open and close the transfer opening of the vacuum chamber for introducing and discharging components.

[0006] Vacuum valves through which semiconductor components pass are called vacuum transfer valves, based on the described application and associated dimensional settings; often also called square valves, based on their square opening cross-section; and also called slide valves, square sliders, or transfer slide valves, based on the usual functional form of vacuum valves.

[0007] Peripheral valves are used, in particular, to control or regulate the gas flow between a vacuum chamber and one vacuum pump or another vacuum chamber. Peripheral valves are located, for example, within a piping system, between a process vacuum chamber or transfer chamber and a vacuum pump, atmosphere, or another process vacuum chamber. The opening cross-section of such valves, also called pump valves, is typically smaller than that of vacuum transfer valves. Peripheral valves are also called regulating valves because, depending on the field of application, they can be used not only to completely open and close their openings, but also for controlling or regulating the flow rate by continuously adjusting the opening cross-section between a fully open position and a gas-tight closed position. One possible peripheral valve for controlling or regulating gas flow is a shuttle valve.

[0008] For example, in a typical shuttle valve known under U.S. Patent No. 6,089,537 (Olmsted), in the first step, a valve plate, usually round, is pivotally rotated over a typically round opening, from a position that opens the opening to an intermediate position that covers the opening. In a slide valve, for example, as described in U.S. Patent No. 6,416,037 (Geiser) or U.S. Patent No. 6,056,266 (Blecha), the valve plate and opening are often rectangular, and in this first step, they are moved linearly from a position that opens the opening to an intermediate position that covers the opening. At this intermediate position, the valve plate of the shuttle valve or slide valve is positioned spaced opposite to the valve seat surrounding the opening. In the second step, the gap between the valve plate and the valve seat is reduced so that the valve plate and the valve seat are evenly pressed against each other, and the opening is closed substantially gas-tight. This second movement is preferably performed in a direction substantially perpendicular to the valve seat.

[0009] The seal can be formed, for example, via a seal ring positioned on the closing side of the valve plate and pressed against a valve seat extending to surround the opening, or via a seal ring at the valve seat against which the closing side of the valve plate is pressed. The two-step closing process exposes the seal ring to little shear force between the valve plate and the valve seat that would break the seal ring, because the movement of the valve plate in the second step is substantially linear toward and perpendicular to the valve seat.

[0010] Different sealing devices are known in the prior art, for example, under U.S. Patent No. 6,629,682 (Duelli). Suitable materials for sealing rings and packings in vacuum valves are, for example, fluororubber, also known as FKM, particularly fluoroelastomer known by the trade name "Viton", and perfluororubber, abbreviated as FFKM.

[0011] Based on the prior art, different drive systems for obtaining this combination of rotational motion of the valve plate in a shuttle valve and translational motion of the valve plate in a slide valve, which move parallel to the opening, and substantially translational motion perpendicular to the opening are known, for example, based on U.S. Patent No. 6,089,537 (Olmsted) for shuttle valves and U.S. Patent No. 6,416,037 (Geiser) for slide valves.

[0012] The described multi-stage motion, in which the closing member is first shifted laterally over the opening without contact between the packing and the valve seat, and then the closing member is pressed substantially vertically against the valve seat, offers not only the advantage that the packing is pressed almost completely vertically and no lateral or longitudinal load is generated on the packing (particle avoidance), but also the possibility of adjusting the flow rate of the medium (e.g., process gas) passing through the valve opening.

[0013] Such vacuum valves are particularly necessary for vacuum chambers configured for the technical use of low-pressure plasma. Low-pressure plasma is plasma whose pressure is significantly lower than atmospheric pressure. Typical technical low-pressure plasmas operate in a pressure range of a few pascals, that is, at a pressure approximately 10,000 lower than normal air pressure. Low-pressure plasma is an important tool in the manufacture of microelectronic devices or in precision surface processing, for example, by plasma etching or sputtering. For example, in plasma etching of PTFE, the material is removed from the surface by hydrogen plasma. This process is carried out under specific pressures within a vacuum chamber where the electrical excitation of hydrogen gas occurs.

[0014] When using vacuum valves in conjunction with low-pressure plasma, it is necessary for the valves to effectively shield the electromagnetic field inside the process chamber without becoming charged themselves. For this purpose, for example, grounding straps can be used to eliminate potential differences between individual components of the valve, or between the valve and other components of the vacuum chamber system. However, the use of such grounding straps can generate parasitic oscillating circuits with resonant frequencies in the plasma excitation frequency band, which can lead to undesirable plasma discharges ("parasitic discharges"). This parasitic discharge problem becomes more pronounced with increasing power output during electrical excitation.

[0015] Therefore, the fundamental problem of the present invention is to provide an improved vacuum valve and an improved grounding system that reduce or avoid the aforementioned drawbacks.

[0016] Another objective of the present invention is to provide such a vacuum valve and such a grounding system suitable for applications in which low-pressure plasma is used.

[0017] Another object of the present invention is to provide an improved vacuum chamber system having such a vacuum valve and such a grounding system.

[0018] These challenges are resolved by implementing the features described in the feature section of the independent claim. Features that would otherwise or advantageously develop the present invention can be found in the dependent claims.

[0019] A first aspect of the present invention relates to a high-frequency grounding device for use with a vacuum valve for opening and closing a valve opening in a vacuum chamber system. The high-frequency grounding device has a grounding strap made of a conductive material for discharging electric charge generated in the vacuum valve, the grounding strap having a first end and a second end, configured such that the first end is connected to the valve closure of the vacuum valve and the second end is connected to a component of the vacuum chamber system, particularly a housing or wall, for grounding the vacuum valve.

[0020] According to the present invention, the high-frequency grounding device has a compensating impedance, and the grounding strap is connected to the compensating impedance, thereby forming a vibration circuit (Schwingkreis) comprising at least the grounding strap and the compensating impedance. The compensating impedance has a first element for shifting the resonant frequency of the vibration circuit and / or a second element for degrading the quality of the vibration circuit.

[0021] The vibration circuit may have a particularly definable resonant frequency and / or definable quality. The vibration circuit is formed in particular by a compensating impedance, a grounding strap, and a part of a valve, particularly a vacuum valve or valve closure, and its parasitic impedance.

[0022] The vacuum chamber system includes a process chamber, within which a low-pressure plasma may be generated by excitation at a specific excitation frequency. The low-pressure plasma can be generated particularly by short-wave excitation, and the excitation frequency of the low-pressure plasma may be, for example, 13.56 MHz.

[0023] In this case, the correction impedance has a first element, which is configured such that the resonant frequency of the oscillating circuit is away from the excitation frequency of the low-pressure plasma, in particular, such that the resonant frequency is at least 20% below the excitation frequency.

[0024] In one embodiment, the first element may be configured such that the oscillating circuit has a resonance frequency that is less than half of the excitation frequency of the low-pressure plasma, particularly less than 1 / 4 of the excitation frequency.

[0025] The vacuum chamber system has a lock chamber pre-positioned to the process chamber, and the lock chamber and the periphery of the vacuum chamber system are connected to each other by a first vacuum valve, and the process chamber and the lock chamber may be connected to each other by a second vacuum valve. <00……Full translation is as follows:

[0024] In one embodiment, the first element may be configured such that the oscillating circuit has a resonance frequency that is less than half of the excitation frequency of the low-pressure plasma, particularly less than 1 / 4 of the excitation frequency.

[0025] The vacuum chamber system has a lock chamber pre-positioned to the process chamber, and the lock chamber and the periphery of the vacuum chamber system are connected to each other by a first vacuum valve, and the process chamber and the lock chamber may be connected to each other by a second vacuum valve.

[0026] In one embodiment, the high-frequency grounding device is configured for use with a second vacuum valve, and the valve opening may be an opening between the process chamber and the lock chamber.

[0027] According to one embodiment of the high-frequency grounding device, the correction impedance has at least a second element, and this second element has an electrical resistance of at least 1 Ω (ohm), for example 1 to 100 Ω, in order to reduce the quality of the oscillating circuit. Preferably, the electrical resistance of the second element is significantly higher than the electrical resistance of the grounding strap, for example more than twice as high.

[0028] In one embodiment, the second element is configured such that the quality factor Q of the oscillating circuit is less than 0.5, particularly less than 0.25. For this purpose, the electrical resistance for each oscillating circuit should be appropriately selected, that is, particularly large enough.

[0029] [[ID=2…… According to another embodiment of the high-frequency grounding device, the correction impedance has at least a first element, and this first element has an inductance of 1 to 100 μH (microhenry), for example 10 to 40 μH, in order to shift the resonance frequency. The shift of the resonance frequency may particularly be a decrease.

[0030] According to another embodiment of the high-frequency grounding device, the correction impedance has a coil as a first element, the coil having a bobbin (Koerper) and a metal wire wound around the bobbin, the bobbin being, for example, cylindrical.

[0031] In one embodiment, the bobbin of the coil consists entirely or partly of polyether ether ketone (PEEK). In particular, the proportion of PEEK is at least 25%. It has been found that PEEK is particularly suitable as a coil bobbin material for use in high vacuum.

[0032] In one embodiment, the coil has 12 to 25 turns, for example 22 turns, of the metal wire around the bobbin. In one embodiment, the metal wire has a diameter of about 0.6 mm.

[0033] In one embodiment, the metal wire is a steel wire, particularly made of stainless steel. Such a steel wire has been found to be particularly suitable for use in high vacuum.

[0034] In another embodiment of the high-frequency grounding device, the grounding strap is a metal strap, particularly a steel strap made of stainless steel, and has a length of at least 50 cm between the first end and the second end. Such a steel strap may particularly have an electrical resistance of less than 1 Ω.

[0035] A second aspect of the present invention relates to a vacuum valve configured as a vacuum valve, for example a vacuum transfer valve, for opening and closing a valve opening of a vacuum chamber system. The vacuum valve comprises a valve seat having a valve opening defining an opening axis and a first sealing surface extending around the valve opening, a valve closing body (valve plate) for adjusting the volume flow or mass flow and / or for substantially gas-tightly closing the valve opening by a second sealing surface corresponding to the first sealing surface, and a grounding device provided with a grounding strap for discharging the generated charges.

[0036] According to this aspect of the present invention, the grounding device is configured as a high-frequency grounding device according to the first aspect of the present invention. That is, the high-frequency grounding device has a grounding strap made of a conductive material for guiding the charge generated in the vacuum valve, the grounding strap having a first end and a second end, configured to be connected to a valve closure at the first end and to a member of the vacuum chamber system at the second end for grounding the vacuum valve. Furthermore, the high-frequency grounding device has a compensating impedance, and the grounding strap is connected to the compensating impedance, thereby forming a vibration circuit comprising at least the grounding strap and the compensating impedance. The compensating impedance has a first element for shifting the resonant frequency of the vibration circuit and / or a second element for degrading the quality of the vibration circuit.

[0037] In one embodiment, the vacuum valve has exactly one such high-frequency grounding device comprising exactly one grounding strap and exactly one coil as a first element of compensating impedance.

[0038] In one other embodiment, the vacuum valve has a drive unit connected to a valve closure body, which is configured to provide motion of the valve closure body such that the valve closure body is movable and reversible from an open position in which the valve closure body opens at least partially to a closed position in which a first sealing surface and a second sealing surface are in close contact with a sealing material located between them, thereby closing the valve opening gas-tightly.

[0039] In one embodiment, the vacuum valve has a bellows coupled to a valve closure and a valve housing to isolate the drive unit from the process volume to the atmosphere, wherein the bellows is configured and arranged to be compressed in the open position and extended in the closed position.

[0040] A third aspect of the present invention relates to a vacuum chamber system comprising a process chamber capable of generating a low-pressure plasma internally and a lock chamber positioned in front of the process chamber. According to this aspect of the present invention, the vacuum chamber system has at least one vacuum valve according to the second aspect of the present invention, which is equipped with a high-frequency grounding device according to the first aspect of the present invention.

[0041] In one embodiment, a low-pressure plasma can be generated in the process chamber by excitation at an excitation frequency. The low-pressure plasma can be generated particularly by short-wave excitation, and the excitation frequency of the low-pressure plasma may be, for example, 13.56 MHz.

[0042] In one embodiment, the lock chamber and the surrounding vacuum chamber system are connected to each other by a first vacuum valve, and the process chamber and the lock chamber are connected to each other by a second vacuum valve. In particular, the second vacuum valve may be configured as a vacuum valve according to a second aspect of the present invention.

[0043] Next, the high-frequency grounding device, vacuum valve, and vacuum chamber system according to the present invention will be described in detail purely as examples, with reference to the schematic embodiments shown in the drawings. The embodiments described are not necessarily shown in dimensional terms and should not be understood as limiting. [Brief explanation of the drawing]

[0044] [Figure 1] This figure shows an example of an embodiment of a vacuum chamber system according to the present invention, which includes a vacuum valve and a high-frequency grounding device. [Figure 2] Figure 1 is a cross-sectional view showing the vacuum chamber system. [Figure 3] Figures 3a to 3c show an example of an embodiment of a vacuum valve according to the present invention equipped with a high-frequency grounding device. [Figure 4] This figure shows a vibration circuit formed by an example high-frequency grounding device. [Figure 5]This figure shows an example of an embodiment of the high-frequency grounding device according to the present invention. [Figure 6] Figures 6a and 6b show the high-frequency grounding device of Figure 5 in an example of an embodiment of the vacuum valve according to the present invention. [Figure 7] Figures 7a and 7b show an example of another embodiment of the vacuum chamber system according to the present invention, which includes a vacuum valve and a high-frequency grounding device.

[0045] Figure 1 shows an example of an embodiment of a vacuum chamber system 50 for the technical use of low-pressure plasma. The vacuum chamber system 50 has a vacuum valve 1 equipped with a high-frequency grounding device 40 according to the present invention. It is desirable that the vacuum valve 1 effectively shields the electromagnetic field inside the process chamber without becoming charged itself. To this end, a grounding strap 42 is used to eliminate the potential difference between the vacuum valve 1 (or the closing body of the vacuum valve 1, so-called valve plate) and the outer wall of the vacuum chamber system 50. In particular, the high-frequency grounding device 40 can also derive the sheath current.

[0046] According to the present invention, a compensating impedance is provided to prevent the grounding device from forming a parallel resonant circuit having a resonant frequency in a problematic band. The compensating impedance may, for example, have a coil 45 that modulates the frequency of the vibration circuit. Alternatively or additionally, the compensating impedance may have an electrical resistance that degrades the quality of the parasitic vibration circuit to a state where the impedance is always limited. The exact configuration of the compensating impedance is related to the specifications of the vacuum valve 1 and the frequency to be protected (freizuhaltend.), i.e., the process frequency in particular within the vacuum chamber system 50.

[0047] Figure 2 shows a cross-sectional view of the vacuum chamber system 50. The vacuum chamber system 50 has a process chamber 52 in which a low-pressure plasma can be generated and used for various technical applications. A lock chamber 51 is positioned in front of the process chamber 52. In the illustrated embodiment, a first vacuum valve 1 is provided between the lock chamber 51 and the outside atmosphere, and this first vacuum valve 1 opens and closes a valve opening 2 as needed by a valve closure 4 (valve plate). A second vacuum valve 1' is provided between the lock chamber 51 and the process chamber 52. This structure makes it possible to keep the pressure inside the process chamber 52 consistently low for a relatively long period of time. One or both of these valves 1, 1' may be configured with a high-frequency grounding device 40 according to the present invention.

[0048] In the embodiment shown herein, only the first vacuum valve 1 is configured to be equipped with the high-frequency grounding device according to the present invention. The valve closure 4 is located on a movable arm 5, which is mechanically connected to a drive unit 7. The grounding strap 42 of the high-frequency grounding device connects the valve closure 4 to the housing of the vacuum chamber system 50 in order to ground the vacuum valve 1. The grounding strap 42 is then connected to a correction impedance of the grounding device, which is configured here as a coil 45. According to the present invention, the correction impedance is configured to have resistance and reactance that work to adequately distinguish between the resonant frequency of the parasitic oscillatory circuit formed by the high-frequency grounding device and the excitation frequency of the low-pressure plasma.

[0049] If the resonant frequency of the grounding strap 42 is, for example, about 15 MHz without the coil 45 (or other compensating impedance), this can cause undesirable plasma discharge in the case of short-wave excitation of a 13.56 MHz plasma. By adding a compensating impedance such as the coil 45, the resonant frequency can thus be shifted to a safe band, particularly a frequency less than half the excitation frequency.

[0050] Figures 3a to 3c show one embodiment of the vacuum valve 1 according to the present invention, which is formed as a vacuum transfer valve and shown in different closed positions (O, Z, S). The illustrated vacuum valve 1 has a rectangular plate-shaped valve closure 4 (valve plate), which has a sealing surface 6 (second sealing surface) for gas-tightly closing the opening 2. The opening 2 has a cross-section corresponding to the valve closure 4 and is formed in a wall 12. The wall 12 may be, for example, the wall of the vacuum chamber system shown in Figures 1 and 2. The opening 2 is surrounded by a valve seat, which itself also provides a sealing surface 3 (first sealing surface) corresponding to the sealing surface 6 of the valve closure 4. The sealing surface 6 of the valve closure 4 extends annularly in the valve closure 4 and has a sealing material (packing). In the closed position S (Figure 3c), the packing is compressed between the sealing surface 6 and the sealing surface 3.

[0051] The opening 2 connects a first gas region L located to the left of wall 12 to a second gas region R located to the right of wall 12. Wall 12 is formed, for example, by the chamber wall of a vacuum chamber system or a lock chamber (see Figure 2). The vacuum valve 1 is formed by the cooperation of the chamber wall 12 and the valve closure 4. The first gas region may have atmospheric pressure, while the second gas region inside the vacuum chamber system or lock chamber may have a pressure lower than atmospheric pressure, particularly a vacuum, when the vacuum valve is closed.

[0052] As can be seen from the figure, the valve seat may, alternatively, be formed together with the first sealing surface 3 as a valve component that is structurally immovably coupled to the valve 1, for example, at the chamber opening, for example, by screw coupling.

[0053] The valve closing member 4, as shown here, may be positioned on a movable arm 5, which is, for example, rod-shaped, and extends along a geometrical axis of movement V. The movable arm 5 is mechanically connected to a drive unit 7, which allows the closing member 4 to move from an open position O (Figure 3a) through an intermediate position Z (Figure 3b) to a closed position S (Figure 3c) in the first gas region L to the left of the wall 12 by the movement of the movable arm 5 using the drive unit 7.

[0054] In the open position O, the valve closure body 4 is outside the projection range of the opening 2, and the opening 2 is completely open as shown in Figure 3a.

[0055] The valve closure body 4 can be moved from the open position O to the intermediate position Z by the drive unit 7 through linear movement of the valve closure body 4 in the axial direction in a plane that is parallel or coaxial with the movement axis V and parallel to the wall 12.

[0056] At this intermediate position Z (Figure 3b), the sealing surface 6 of the valve closure body 4 is positioned opposite the sealing surface 3 of the valve seat that surrounds the opening 2, with a gap between them.

[0057] The valve closure body 4 can be moved from the intermediate position Z to the closed position S (Figure 3c) by movement along the opening axis A defined by the opening 2 (here, laterally relative to the movement axis V), that is, by movement in a direction perpendicular to, for example, the wall 12 and the valve seat.

[0058] In the closed position S, the valve plate 4 gas-tightly closes the opening 2, gas-tightly separating the first gas region L from the second gas region R, for example, inside the lock chamber of a vacuum chamber system. The opening and closing of the vacuum valve is performed by the drive unit 7, in this case, for example, by the L-shaped movement of the valve closure body 4 in two mutually perpendicular directions V and A. Therefore, the valve shown is also called an L-shaped valve.

[0059] Instead of the embodiments of the vacuum valve shown purely as examples in Figures 3a and 3c, the vacuum valve according to the present invention may be configured in other forms, for example, as a shuttle valve or single valve as described in detail in German Patent Application Publication No. 102021000787.5. In particular, the vacuum valve may further have a bellows coupled on one side to the valve closure and on the other side to the valve housing. This allows the drive unit and valve arm to be atmospherically isolated from the process volume. The bellows is compressed in the open valve state and extended when the valve is closed.

[0060] According to the present invention, the vacuum valve 1 has a high-frequency grounding device with a grounding strap 42 and a compensating impedance, the compensating impedance here configured as a coil 45. The first end of the grounding strap 42 is fixed to the valve closure 4 and moves together with the valve closure 4 during the opening or closing process. The second end of the grounding strap 42 is fixed together with the coil 45 to the wall 12 (or another part of the housing of the vacuum chamber system) thereby equalizing the potential between the valve plate 4 and the valve housing (grounding). Since the distance between the valve closure 4 and the coil 45 changes in proportion to the mobility of the valve plate 4, the length of the grounding strap must be selected accordingly.

[0061] In the vacuum valve 1 shown in Figures 3a to 3c, the small gap between the valve closing body 4 and the wall 12 in the closed position S causes the capacitor X C A layer is formed, and the non-charged packing 6 acts as a dielectric. Without affecting the function of the vacuum valve, this capacitor X C The capacitance C can be changed just a little bit.

[0062] Figure 4 schematically shows the configuration of the vibration circuit formed by the components of the high-frequency grounding system when the components of the high-frequency grounding system form a connection between the vacuum valve and the vacuum chamber housing for grounding. In Figure 4, X C represents a capacitor with capacitance C, and XL represents a coil (or similar element) with inductance L, and R represents electrical resistance.

[0063] The resonant frequency of this vibration circuit depends on L and C, and is therefore affected by changes in L or C. In contrast, the quality Q of the vibration circuit depends on L, C, and resistance R. Since C cannot be influenced by a sufficient value, the vibration circuit can be tuned to a specific frequency by a properly designed compensating impedance according to the present invention. The inductance L and resistance R can be appropriately adjusted, for example, by the appropriate structural configuration of the coil 45 or other elements.

[0064] As is known to those skilled in the art, the compensating impedance may be formed in other forms instead of the coil 45. In particular, a circuit consisting of electrical components, such as a circuit having a choke coil and a resistor in one common component, is possible.

[0065] Figure 5 shows the high-frequency grounding system 40 in detail, disconnected from the vacuum valve. Such a high-frequency grounding system 40 is preferably suitable for use in high vacuum with respect to the materials and components used. In particular, it is desirable that none of the materials used release gas in a vacuum.

[0066] The illustrated grounding system 40 includes a grounding strap 42 made of special stainless steel and a compensating impedance in the form of a coil 45. The grounding strap 42 may have a length of, for example, about 0.5 m to 1 m.

[0067] The electrical resistance of such a grounding strap 42, made of special steel, is relatively low, for example, obviously less than 1 ohm. The grounding strap 42 is electrically connected at its first end 41 by terminals to a first connecting member 44 which is to be attached to a vacuum valve, in particular to the valve plate. The grounding strap is electrically connected at its second end 43 to a coil 45. The coil 45 has a reel 46 made of the same material as the grounding strap 42, for example, on which an insulated metal wire 47 is wound. The end 48 of the wire is connected to the second end 43 of the grounding strap 42.

[0068] The coil 45, acting as a compensating impedance, is configured such that the oscillating circuit has a resonant frequency that is distinctly different from the excitation frequency of the low-pressure plasma generated within the vacuum chamber system, particularly a resonant frequency that is distinctly lower than the excitation frequency. In most applications, it is preferable to shift the excitation frequency to a lower frequency band rather than a higher frequency band, because this avoids harmonics. For example, the resonant frequency generated by the compensating impedance can be less than half of the excitation frequency. A typical excitation frequency for a low-pressure plasma is 13.56 MHz. In this case, the resonant frequency reduced by the coil 45 should preferably be less than 10 MHz, and more preferably less than 5 MHz. This reduces or eliminates the risk of parasitic discharge.

[0069] Therefore, in this case, it is desirable that the coil 45 be configured such that its inductance is 1 μH to 100 μH (microhenries), thereby appropriately shifting the resonant frequency of each vacuum valve to a desired location. The inductance and parasitic resistance of the coil 45 can be influenced, for example, by the selection of the wire 47 and, for example, by the selection of the winding frame 46 (core) surrounded by the wire 47. At this time, it is desirable that the inductance L be selected to be as large as possible in order to sufficiently reduce the resonant frequency, and on the other hand, it is desirable that the structural cost not be excessively high.

[0070] For example, the insulated wire 47 is made of a special stainless steel and has a diameter of approximately 0.6 mm. The end 48 of the wire is connected to the second end 43 of the grounding strap 42. The cylindrical coil reel 46 is made of polyetheretherketone (PEEK) and is placed on a fixing plate 49, which can be grounded and connected to the housing of the vacuum chamber system. Depending on the inductance required to obtain the desired resonant frequency, the coil 45 may have a different number of turns of the steel wire 47, for example, 12 to 25 turns around the PEEK reel 46.

[0071] In place of or in addition to the coil 45, other elements that increase the inductance L, such as a spring or a helical body, may be used. Furthermore, these elements do not necessarily have to be attached to one end of the grounding strap 42; for example, they may be configured in the middle between two parts of the strap 42, or they may be configured as an integral part of the strap 42 (e.g., a helical strap).

[0072] In place of or in addition to a coil, or in place of or in addition to other elements that increase the inductance L, the compensating impedance may include electrical resistance R. Such resistance degrades the quality of the oscillating circuit.

[0073] Preferably, the resistance is such that the quality factor Q of the vibration circuit is reduced to less than 1, and particularly less than 0.5. In particular, at least one of the terminals can provide electrical resistance, such as a connecting member 44, to the ends 41, 43 of the grounding strap 42. In particular, when the resistance is used without a coil 45 or without a compensating impedance element for the same effect, i.e., an element that shifts the resonant frequency, it is desirable that the electrical resistance R is clearly greater than the electrical resistance of the grounding strap 42. Depending on the characteristics of the valve and the grounding strap 42, and if a coil 45 or other element that increases the inductance L is provided in addition, a resistance in the range of 0.5 to 1000 Ω, particularly in the range of 1 to 100 Ω, is advantageous in relation to this inductance L. In this way, the quality of the vibration circuit can be sufficiently reduced without simultaneously impairing the grounding function.

[0074] Figures 6a and 6b show the high-frequency grounding system shown in Figure 5, installed in an example of an embodiment of a vacuum valve in a vacuum chamber system. In Figure 6a, the vacuum valve is shown in the open position O, in which the valve opening 2 is not covered by the valve plate 4. In Figure 6b, the same vacuum valve is shown in the closed position S, in which the valve plate 4 is moved in front of the valve opening 2 by the drive unit 7 and the movable arm 5, completely closing the valve opening 2. The first end of the grounding strap 42 is fixed here to the side of the valve plate 4 and is movable together with the valve plate 4. The second end of the grounding strap 42 is fixed together with the coil 45 to the vacuum chamber system or the wall 12 of the valve body, thereby grounding the valve plate 4.

[0075] The length of the grounding strap must be carefully selected to match the mobility of the valve plate 4.

[0076] Figures 7a and 7b show a cross-sectional view of another example of an embodiment of the vacuum chamber system according to the present invention, comprising a vacuum valve and a high-frequency grounding device. The vacuum chamber system 50 has a process chamber 52 in which a low-pressure plasma can be generated and is available for various technical uses. A lock chamber 51 is positioned in front of the process chamber 52. A first vacuum valve 1 is provided between the lock chamber 51 and the outside atmosphere, and the first vacuum valve 1 opens and closes the valve opening 2 as needed by a valve closure body 4 (valve plate). A second vacuum valve 1' is provided between the lock chamber 51 and the process chamber 52. This structure makes it possible to keep the pressure inside the process chamber 52 consistently low for a relatively long period of time.

[0077] Both vacuum valves 1 and 1' are configured as vacuum transfer valves. In the first state shown in Figure 7a, the first vacuum valve 1 is in the closed position S, and the second vacuum valve 1' is in the open position O. In the second state shown in Figure 7b, the first vacuum valve 1 is in the open position O, and the second vacuum valve 1' is in the closed position S.

[0078] Unlike the embodiment shown in Figure 2, the second vacuum valve 1' is configured to be equipped with the high-frequency grounding device according to the present invention. Alternatively, the first vacuum valve 1 and the second vacuum valve 1' may each be configured to be equipped with the high-frequency grounding device according to the present invention.

[0079] The second vacuum valve 1' has two valve closures 4, 4', both of which are located on a movable arm 5 that is mechanically connected to a drive unit 7. In the closed position S, valve closure 4' closes the opening of the lock chamber 51, and valve closure 4 closes the opening of the process chamber 52.

[0080] The grounding strap 42 of the high-frequency grounding device connects a valve closure body 4, which closes an opening leading to the process chamber 52, to the inner wall of the vacuum chamber system 50 in order to ground the vacuum valve 1'. On the inner wall, the grounding strap 42 is connected to a coil 45 (which acts as the corrective impedance of the grounding device). Therefore, this configuration of the high-frequency grounding device is approximately equivalent to the configuration shown in Figures 6a and 6b, and in this cross-sectional view, most of the valve plate 4 is covered by the grounding strap 42.

[0081] Coil 45 (correction impedance) is configured to have resistance and reactance, and this reactance works to sufficiently differentiate the resonant frequency of the parasitic oscillatory circuit formed by the high-frequency grounding device from the excitation frequency of the low-pressure plasma.

[0082] Since the high-frequency grounding device is located inside the vacuum chamber system 50, it is desirable that all its components be suitable for reliable use in a high vacuum.

[0083] Naturally, these figures shown are merely schematic representations of possible embodiments. Various configurations can be combined with each other, and various configurations can be combined with prior art apparatus and methods.

Claims

1. A high-frequency grounding device (40) for use with vacuum valves (1, 1') for opening and closing valve openings (2) of a vacuum chamber system (50), comprising a grounding strap (42) made of a conductive material for guiding the charge generated in the vacuum valve (1), wherein the grounding strap (42) has a first end (41) and a second end (43), and is configured to be connected at the first end (41) to the valve closure body (4) of the vacuum valves (1, 1') and at the second end (43) to a component of the vacuum chamber system (50) for grounding the vacuum valves (1, 1'), The high-frequency grounding device (40) has a correction impedance, - The grounding strap (42) is connected to the correction impedance, thereby forming a vibration circuit comprising the grounding strap (42) and the correction impedance. - The correction impedance has a first element for shifting the resonant frequency of the vibration circuit and / or a second element for degrading the quality of the vibration circuit. A high-frequency grounding device (40) characterized by the above.

2. The high-frequency grounding device (40) according to claim 1, wherein the vacuum chamber system (50) has a process chamber (52) and a low-pressure plasma can be generated in the process chamber (52) by excitation at an excitation frequency.

3. The low-pressure plasma can be generated by short-wave excitation, according to the high-frequency grounding device (40) of claim 2.

4. The high-frequency grounding device (40) according to claim 2, wherein the correction impedance has the first element, the first element is configured to move the resonant frequency of the vibration circuit away from the excitation frequency of the low-pressure plasma.

5. The high-frequency grounding device (40) according to claim 4, wherein the first element is configured such that the vibration circuit has a resonant frequency that is less than half the excitation frequency of the low-pressure plasma.

6. The vacuum chamber system (50) has a lock chamber (51) positioned in front of the process chamber (52), - The lock chamber (51) and the periphery of the vacuum chamber system (50) are connected to each other by the first vacuum valve (1). - The process chamber (52) and the lock chamber (51) are connected to each other by a second vacuum valve (1'). The high-frequency grounding device (40) according to claim 2.

7. The high-frequency grounding device (40) according to claim 6, wherein the high-frequency grounding device (40) is configured for use in conjunction with the second vacuum valve (1'), and the valve opening (2) is an opening between the process chamber (52) and the lock chamber (51).

8. The high-frequency grounding device (40) according to claim 1, wherein the correction impedance has at least a second element, the second element having an electrical resistance of at least 1 ohm to degrade the quality of the vibration circuit.

9. The high-frequency grounding device (40) according to claim 8, wherein the second element is configured such that the quality factor of the vibration circuit is less than 0.

5.

10. The high-frequency grounding device (40) according to claim 1, wherein the correction impedance has at least the first element, and the first element has an inductance of 1 to 100 μH to shift the resonant frequency.

11. The correction impedance has at least the first element, the first element being configured as a coil (45), and the coil (45) having a winding frame (46) and a metal wire (47) wound around the winding frame, according to claim 1, the high-frequency grounding device (40).

12. The high-frequency grounding device (40) according to claim 11, wherein the winding frame (46) is made of polyetheretherketone or contains a predetermined proportion of polyetheretherketone.

13. - The coil (45) has 12 to 25 turns of the metal wire (47) around the winding frame (46), - The metal wire (47) is a steel wire and / or - The metal wire (47) has a diameter of 0.6 mm. The high-frequency grounding device (40) according to claim 11.

14. The aforementioned grounding strap (42) is - It is a metal strap, - Having a length of at least 50 cm between the first end (41) and the second end (43), The high-frequency grounding device (40) according to claim 1.

15. The vibration circuit is - Having a specified resonant frequency and / or specified quality, and / or - Formed by the correction impedance, the grounding strap (42), and a part of the vacuum valve (1, 1'), The high-frequency grounding device (40) according to claim 1.

16. A vacuum valve (1, 1') for opening and closing the valve opening (2) of a vacuum chamber system (50), - A valve seat having a valve opening (2) that defines an opening axis (A) and a first sealing surface (3) that extends to surround the valve opening (2), - A valve closing body (4) for adjusting the volumetric flow rate or mass flow rate and / or substantially closing the valve opening (2) with a second sealing surface (6) corresponding to the first sealing surface (3), - A grounding device equipped with a grounding strap (42) for grounding the generated charge and Equipped with, The vacuum valve (1, 1') is characterized in that the grounding device is configured as the high-frequency grounding device (40) described in claim 1.

17. The vacuum valve (1, 1') according to claim 16, having exactly one high-frequency grounding device (40) comprising exactly one grounding strap (42) and exactly one coil (45) as a first element of the correcting impedance.

18. The vacuum valve (1, 1') according to claim 16, comprising a drive unit (7) connected to the valve closure (4), wherein the drive unit (7) is configured to provide motion of the valve closure (4) such that the valve closure (4) can move from an open position (O) in which the valve closure (4) opens the valve opening (2) at least partially, to a closed position (S) in which the first sealing surface (3) and the second sealing surface (6) are in close contact with a sealing material located between them, thereby closing the valve opening (2) in a gas-tight manner.

19. The vacuum valve (1, 1') according to claim 18, having a bellows coupled to the valve closure (4) and the housing (9) of the vacuum valve (1, 1') for separating the drive unit from the process volume to the atmosphere, wherein the bellows is configured and arranged to be compressed in the open position (O) and extended in the closed position (S).

20. In a vacuum chamber system (50) comprising a process chamber (52) capable of generating low-pressure plasma internally and a lock chamber (51) positioned in front of the process chamber (52), A vacuum chamber system (50) comprising at least one vacuum valve (1,1') as described in claim 16.

Images