JP2013213498A - Pump system for vacuuming gas from multiple chambers and method for controlling pump system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To optimally use a maximally large number of pumps from an economical viewpoint and a technical viewpoint, and to maximally similarly distribute a generating gas load to a plurality of maximally simple and resembled or similar pumps so as not to have reaction to a process.SOLUTION: A pump system is provided for discharging gas from a plurality of chambers 1 and 2 having at least three vacuum pumps. When at least two pre-pumps 5 and 6 and at least one turbo molecular pump 3 are provided, at least one cross-section reducing part 9 for adjusting and/or reducing a gas flow, is arranged in at least one connecting pipe 8 between at least the two pre-pumps 5 and 6.

Description

  The present invention relates to a pump system for evacuating gas from a plurality of chambers and a method for controlling the pump system.

  The entire system actually consists of one or more vacuum chambers (receivers). These chambers can be used individually, but are also at least partially connected to each other. In this case, due to the pressure difference between the two chambers, the conductance of the opening in the common wall between the two process chambers, or the conductance of the connecting pipe line, causes the gas flow between them to flow. Determine. In addition, one or more chambers are exposed to gas loads, which are largely process dependent, with connections to the outside of the chamber (“atmosphere environment”), and gas loads relayed from the pre-connected chamber. Depending on the other gas flow generated, the introduction of an inert or process gas, typically a noble gas such as helium, can also be used for workpieces, specimens and / or chamber components carried into the chamber. It is generated by Desorption and / or by reaction products that are actively generated during the process.

  In order to maintain the process in each chamber, they must be evacuated to the intended vacuum pressure by the respective connected vacuum pump system, and the pressure must then be kept as constant as possible. Each of these individual vacuum pump systems consists of one individual pump or a series and / or parallel connection of a plurality of pumps. Depending on the amount of gas generated, it is also possible for several chambers to be evacuated simultaneously by individual pumps, or for several pumps to be evacuated by one common pre-pump. Between the chamber and the pump, a series connection, a parallel connection, or any combination thereof can be implemented as a connection.

  From the prior art (Patent Document 1) it is known that pumps can be mutually assisted in an appropriate manner by being connected to different pressure levels inside other pumps.

  In many cases, the process in a multi-chamber system requires a high gas load under low pressure, so a large pre-pump needs to be used there to be able to maintain the desired vacuum pressure. At the same time, the other chambers of such a system can be kept at vacuum pressure with very low effort, and a small pump is sufficient. The greater the gas load that the pump must handle, the higher its energy demand, and the associated cooling demand, due to gas friction and electrical and mechanical losses.

  It may be advantageous to use a plurality of small pumps instead of one large one according to predetermined ambient and environmental conditions, i.e., for example, in a limited installation space. In addition, it is beneficial to distribute the load as equally as possible to compensate for high pump efficiency.

  For real use cases, gas loads and vacuum pressures vary significantly from chamber to chamber, and adapting to the possibilities described above is difficult with the desired process data, and is profitable. And only possible. The prior art (Patent Document 1) describes one form of solution, but these require multiple special pumps with appropriately selected intermediate connections.

International Publication No. 2011-121322 A2 Specification

  The technical problem underlying the present invention is to make the best possible use of as many pumps as possible from an economic and technical point of view, and to produce as much of the gas load as possible and have a reaction to the process. It is as simple as possible to distribute to multiple pumps that are similar or similar.

  These technical problems are solved by a pump system having the features of claim 1 and by a method having the features of claim 16.

  A pump system according to the invention for evacuating gas from a plurality of chambers having at least three vacuum pumps has at least two pre-pumps and at least one turbo-molecular pump. It stands out in that at least one cross-sectional reduction part for adjusting the gas flow is provided in between.

  According to the invention, between the pumps connected in parallel and / or in series, the maximum gas flow in each piping section is limited by one or more cross-sectional reductions. In the sense of the present invention, a reduced cross-section is understood to include a device for completely closing the piping section.

  The cross-sectional reduction can advantageously be implemented as a simple diaphragm. This is a member having a reduced cross-section defined over a predetermined length of the section.

  In the simplest case, one throttle throttle has one firm (fixed) reduction.

  Another special advantageous embodiment is adjustable within a defined area. This embodiment is referred to as a throttle valve. The adjustment of the region can be performed manually or mechanically, or can be performed electrically, pneumatically or hydraulically by the control drive.

  The adjustment of the throttle valve is advantageously made on the basis of a previously detected and adapted scale, but no feedback is made on the actual cross section or gas flow. For this reason, the gas flow measurement can be performed separately or as a built-in type, so that it can be implemented as a closed adjustment loop, and can be adjusted to a predetermined gas flow. Appropriate preset values are generated electrically as analog signals, for example as voltage, current, pulse width modulation or in other conventional ways, or transmitted as digital signals via any bus system. Alternatively or additionally, the presetting can also be generated from the user interface via one local or remotely connected operating device. These devices are commonly referred to as gas flow regulators. The gas flow regulator is a commercially available member. This is also referred to as a “mass flow controller”.

  The cross-sectional reductions described above can be implemented in a suitable manner, individually or in combination as similar or different embodiments, connected in parallel and / or in series. The use of one or more valves for the separation of one or more subsections of the network used additionally expands the possibility of adaptation to individual process conditions.

  According to another advantageous embodiment of the invention, one or more points in one or more chambers and / or at any point inside the piping section or at any point of the connection of the pump to this or There is also the possibility of using the above-mentioned means for measuring and adjusting the actual vacuum pressure and / or gas flow rate at several locations. The simplest implementation is a single pressure switch, which at the predetermined limit pressure emits a signal for opening or closing a subsection, overloading in the connected pump or Prevent the effects of process assumptions.

  Yet another embodiment of the present invention contemplates a process control (unit) disposed at a higher level. By means of a process control (unit) provided at the upper level, it is possible to use the measured values detected at different points to influence the process judgment and influence, thereby optimizing the process and the load of the individual pumps Can be optimized.

  When using pumps whose pump performance depends at least in part on their discharge pressure, for example when using molecular pumps, these have at least one pump stage on their discharge side. And is beneficial when this pump stage provides constant pump performance over one large pressure region. This can be, for example, a Gede, Ziegburn, and / or a Holweck step (Gaede-, Siegbahn-und / order Holwecktufen). The robustness of the pump against pressure fluctuations on the discharge side allows a clear simplification of the further design of the system. This makes it possible to operate with a simple throttle instead of a switchable or adjustable valve.

  The invention not only prevents significantly different pump structural sizes, but also allows two or more of the same pumps to be used at different locations if possible, whereby products, sales, It is possible to keep the number of variations in integration and use low, thereby realizing cost reductions for manufacturers and customers. These cost reductions are achieved in particular by lowering evaluation costs. Evaluation costs are what pumps are best able to do the work required in combination, either in a country-specific preset voltage network or at a country-specific preset frequency, It means to try using multiple pumps of the same structure. This strategy can be applied to the pump in the pre-evacuation region as in the above-mentioned example, and also applies to the pump connected directly to the chamber or via a connecting pipe. It is possible.

  The described solution is that, for example in the case of an “additional gas load” where helium is introduced as process gas, one pump pumps mainly light gas (low particle mass) during at least one process state at low load This leads to advantages in a system that has to be done, ie in a so-called LCMS system, for example. The efficiency of most pump principles depends on the atomic or molecular weight that must be pumped, and light gases with low mass are generally difficult to pump. When heavy gas is used as the transport medium, the pump performance of such a pump is significantly higher. In this case, the backflow of light gas is reduced in this way, as the heavy particles carry the lighter through the pump in the right direction. The pump as a whole must pump more gas, but the pump performance for light gases is clearly improved. The unloading of the first pump, which discharges a gas stream with a small proportion of light gas to the second pump through the cross-section reduction, is in this case corresponding to the second pump that pumps a high proportion of light gas. As a result, the light gas can be clearly pumped well.

  Pumps that are often operated via frequency converters in the current supply network at each location are at country-specific network frequencies (typically 50 Hz or 60 Hz) or network voltages (typically 90 v, 110 v, 230 v). Rotate at different speeds and / or various maximum drive performances (eg by limiting the drive current or with heat introduction resulting therefrom) and thereby changing its maximum pump performance. This leads to a chamber that is directly evacuated by such a pump being pumped to different pressure levels depending on the current supply network present. In order to prevent this, according to conventional practice, the gas flow inside or in the chamber is adjusted by adapting a control valve or throttle throttle as follows: It was necessary to adjust to be achieved in the network or planned current supply network. This is not easily achievable depending on the complexity of the gas system and is associated with high costs. This is because in many cases multiple corresponding chambers are involved. The problem is that according to the invention, the first pump of variable speed and / or variable drive performance and at least one of the pumping areas where chamber pressure is not important and / or directly connected to the chamber It can be solved by the incorporation of at least one cross-sectional reduction at least intended between the pump, for example a second pump that generates pre-pressure for one or more molecular pumps. In this case, they react to the discharge side while having robustness against pressure fluctuations. Since the above-described replacement or adjustment of the cross-sectional reduction portion adjusts the difference in pump performance of the first pump, the chamber pressure remains constant, and no interference in the chamber or in the chamber need be scheduled in advance. Such adjustment can also be performed by an adjustment unit connected internally or externally as described above. This adjustment unit detects the process conditions, ie the vacuum pressure of the chamber, for example, and adjusts them to the desired value in the current process state by adjusting the cross-section reduction.

  The problem can also be solved by adjusting the variable pump performance based on differences in pump operating conditions rather than on the effects of the current supply network. This indicates a special ambient temperature and / or cooling water temperature, different pump performance, at operating temperature conditions or at various ambient conditions.

  Typical implementations have two or more chambers that are at least partially connected to one another, and these are often operated at different vacuum pressures. The gas stream is generated by the introduction of the gas to be analyzed and often by the introduction of further auxiliary gases into other chambers. Optionally, a vacuum is generated directly by the pre-pump in one or more chambers, otherwise the one or more chambers are evacuated by one or more molecular pumps. This molecular pump is again assisted by one or more pre-pumps in a shared and / or separate manner. Optionally, at least one of the plurality of vacuum pumps has more than one pump inlet (“Branch”, Interstage-Port), wherein the pump inlet is at least one of the first pumps. The other inlet is connected to the other chamber. Advantageously, the pump has a high robustness against high discharge pressures. Typically, the pressure between the molecular pump and the pre-pump is in the range of 1 to 20 mbar (millibar). In order to unload at least one of the at least two pre-pumps, a connection with a reduced cross-section is realized between the suction connection of the former and the second pre-pump, which allows a lot of gas flow. Therefore, the second pre-pump can always maintain at least one predetermined suction pressure. The first unloaded pre-pump can be selected smaller and the second is better utilized.

  Additional features and benefits of the present invention will arise from the accompanying drawings. In the figures, several embodiments of a pump system according to the invention are represented by way of example only.

Pump system according to the prior art. BRIEF DESCRIPTION OF THE DRAWINGS FIG. The simplified diagram of the changed Example. The simplified diagram of the changed Example. The simplified diagram of the changed Example. The simplified diagram of the changed Example. The simplified diagram of the changed Example. The simplified diagram of the changed Example.

  FIG. 1 shows a prior art pump system having two chambers 1, 2 to be evacuated (degassed). A turbo molecular pump 3 is attached to the chamber 1, and a turbo molecular pump 4 is attached to the chamber 2.

  The turbo molecular pump 3 is assisted by a pre-pump 5. The turbo molecular pump 4 is assisted by a pre-pump 6.

  This pump system belonging to the prior art requires that the turbomolecular pump 3 must maintain a predetermined pressure in the chamber 1 and the turbomolecular pump 4 must maintain a predetermined pressure in the chamber 2. Has the disadvantages. These pumps 3, 4, 5 and 6 need to have corresponding capacities. That is, they need to demonstrate the required pump performance under the country-specific conditions of voltage network and frequency.

  The gas flow is represented by the symbol Q. The chambers 1 and 2 are connected to each other. Under different pressures in the chambers 1 and 2, a gas flow Q is generated between the chambers. Further, a gas inlet 7 is provided in the chamber 2 to supply process gas to the chamber 2.

  FIG. 2 shows chambers 1 and 2. These chambers are evacuated by turbo molecular pumps 3 and 4.

  Here, the pre-pumps 5 and 6 assist the turbo molecular pumps 3 and 4.

  A piping section 8 is provided between the pre-pumps 5 and 6. A restriction 9 is provided in the piping section 8 and is simply represented. This restriction 9 makes it possible to adjust the gas flow in the pipe section 8.

  With the device according to the invention, it is possible to form the pumps 3, 4 in the same way, or it is possible to use turbomolecular pumps 3, 4 of the same structure. The load release of the first pump 5 is also performed. This pump discharges a gas flow with a small proportion of light gas to the second pump 6 via the throttle 9. This leads to a corresponding transport effect in the second pump 6 that pumps a high proportion of light gas according to FIG. 2, so that light gas can be pumped clearly well.

  The same applies to the device of FIG. In this apparatus, only a turbo molecular pump 4 for evacuating the chamber 2 is provided.

  The chamber 1 is directly evacuated by the pre-pump 5. In order to assist the turbo molecular pump 4, a pre-pump 6 is provided.

  Between the pre-pumps 5, 6, here again, a single pipe section 8 is provided, which is provided with a restriction 9.

  FIG. 4 shows a modified structure with three chambers 1, 2, 10. According to FIG. 4, both pre-pumps 5 and 6 and a turbo molecular pump 3 for evacuating the chamber 1 are provided. In order to evacuate the chambers 2 and 10, one shunt pump is provided. This diversion pump has two inlets 12 and 13. A pipe section 8 is again provided between the pre-pumps 5 and 6, and a throttle 9 is provided in this pipe section.

  FIG. 5 shows a further embodiment having chambers 1, 2, 10, 13, 14, 15 to be evacuated. The chambers 2, 10, 13 are provided with additional gas inlets 16, 17, 18 for process gas.

  A turbo molecular pump 3 is provided for evacuating the chamber 1. This turbo molecular pump is assisted by a pre-pump 5. In order to evacuate the chambers 2, 13 and 14, a diversion pump 19 is provided, which is assisted by the pre-pump 6.

  One additional turbomolecular pump 20 is provided to evacuate the chamber 15.

  A single pipe section 8 is again provided between the pre-pumps 5 and 6, and a throttle 9 is provided in this pipe section. Here again, the load releasing part of the first pump 5 is intended, and this load releasing part discharges a gas flow containing a small proportion of light gas to the second pump 6 via the cross-section reducing part 9. To do. This leads to a corresponding transport effect in the second pump 6 which pumps a high proportion of light gas in this case, so that light gas can be clearly pumped well.

  FIG. 6 shows an apparatus having chambers 1, 2, 10, 13. The chamber 1 is evacuated by the turbo molecular pump 3, and the chamber 2 is evacuated by the turbo molecular pump 4. Here, the turbo molecular pump 3 is assisted by the pre-pump 5. The turbo molecular pump 4 is assisted by a pre-pump 6.

  A piping section 8 is provided between the pre-pumps 5 and 6, and a throttle 9 is provided in this piping section.

  In order to evacuate the chambers 10 and 13, a diversion pump 11 is provided. This shunt pump is assisted by a pre-pump 21. Between the pre-pump 6 and the pre-pump 21, one additional pipe section 22 is provided, this pipe section being provided with a restriction 23.

  FIG. 7 shows a pump device for a multi-chamber system having chambers 1, 2, 10, 13, 14, and 15.

  The chambers 1, 2, 13, 14, and 15 are evacuated by turbo molecular pumps 3, 4, 20, 24, and 25 having the same structure. Here, the turbo molecular pump 3 is assisted by a pre-pump 5. The pumps 4, 20, 24 and 25 are assisted by the pre-pump 6. A pipe section 8 is also provided between the pre-pump 5 and the pre-pump 6, and a throttle 9 is provided therein.

  FIG. 8 shows a multi-chamber system having chambers 1, 2, 10, 13, 14, 15. The chamber 1 is evacuated by the pre-pump 5. The chambers 2, 13, 14, 15 are evacuated by turbomolecular pumps 4, 20, 24, 25 of the same structure, and here are assisted by a pre-pump 6.

  One pipe section 8 is provided between the pre-pumps 5 and 6, and a throttle 9 is provided therein.

  A device 26 for measuring the current vacuum pressure is provided in the chamber 14.

  Similarly, the pump 20 is provided with a device 27 for measuring the current vacuum pressure at a connecting portion provided for the pump 20.

  In the piping section 29, another device 28 for measuring the gas flow rate is provided.

  A device 30 for measuring the gas flow rate is provided in the piping section 8.

DESCRIPTION OF SYMBOLS 1 Chamber 2 Chamber 3 Turbo molecular pump 4 Turbo molecular pump 5 Prepump 6 Prepump 7 Gas inlet 8 Piping division 9 Throttle 10 Chamber 11 Split flow pump 12 Inlet 13 Inlet 14 Chamber 15 Chamber 16 Gas inlet 17 Gas inlet 18 Gas inlet 19 Split flow pump 20 Turbo molecular pump 21 Pre-pump 22 Piping section 23 Aperture 24 Turbo molecular pump 25 Turbo molecular pump 26 Equipment for measuring vacuum pressure 27 Equipment for measuring vacuum pressure 28 Equipment for measuring gas flow 29 Piping section 30 Measuring gas flow Equipment Q for gas flow

Claims (16)

A pump system for exhausting gas from a plurality of chambers having at least three vacuum pumps, wherein at least two pre-pumps and at least one turbo molecular pump are provided.
In at least one connecting pipe (8) between at least two pre-pumps (5, 6, 21), at least one reduced section (9) for adjusting and / or reducing the gas flow is provided. A pump system characterized by that. Pump system according to claim 1, characterized in that the cross-sectional reduction part (9) is formed as an adjustable cross-sectional reduction part (9). 3. A pump system according to claim 1 or 2, characterized in that at least two turbomolecular pumps (3,4, 20, 24, 25) of the same structure are provided. 4. The pump system according to claim 1, wherein all turbomolecular pumps (3, 4, 20, 24, 25) are formed in the same structure. 5. The pump system according to any one of claims 1 to 4, wherein a throttle, a throttle valve, or a gas flow regulator is provided as the cross-sectional reduction part (9). 6. The pump system according to claim 1, wherein a valve to be adjusted or switched is provided as the cross-sectional reduction part (9). The pump system according to any one of claims 1 to 6, wherein the plurality of cross-sectional reduction portions (9) are provided connected in serial or parallel. The pump system according to any one of claims 1 to 7, further comprising a process control unit disposed at a higher level for adjusting at least one cross-sectional reduction unit. In at least one chamber (1, 2, 10, 13, 14, 15) and / or in at least one piping section (8, 29) and / or in a pump (3,4, 20, 24, 25) A device (26, 27, 28, 30) for measuring the gas flow rate or measuring the current vacuum pressure is provided at the connection point provided for them. The pump system according to any one of 1 to 8. 10. The pump system according to claim 1, wherein a pump depending on a discharge pressure of the pump is provided as the pump (3, 4, 20, 24, 25). 11. The pump system according to claim 1, wherein at least two chambers (1, 2, 10, 13, 14, 15) are connected to each other. 12. The pump system according to claim 1, wherein at least one chamber (1) is directly provided with one pre-pump. 13. At least one pre-pump (5, 6, 21) is pre-installed in at least one turbomolecular pump (3,4, 20, 24, 25). The pump system described in. Some turbomolecular pumps (3,4,20,24,25), or all turbomolecular pumps (3,4,20,24,25) have common and / or separate pre-pumps (5,6, The pump system according to any one of claims 1 to 13, wherein 21) is pre-installed. 15. A pump system according to any one of the preceding claims, characterized in that at least one turbomolecular pump (11, 19) has at least two pump inlets. Method for the control of a pump system having the features of claim 1, wherein the method is in at least one chamber (1, 2, 10, 13, 14, 15) and / or at least one piping section (8, 29) The actual vacuum pressure or gas flow rate is measured at at least one of the above or at the connection point of the pump provided for them, and this at least one measured value is the reduced cross section. A method which is used for the adjustment of (9).

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