Vacuum lines including gas treatment equipment

Abstract

Increase safety in pumping equipment and vacuum lines transporting flammable and / or explosive gases. [Solution] A gas processing device (6) configured to process gas pumped by at least one roughing pumping device (10) at atmospheric pressure, the gas processing device (6) comprising a gas processing chamber (26) and at least one exhaust pipe (7) configured to connect an outlet (8) of the at least one roughing pumping device (10) to an inlet (9) of the gas processing chamber (26), the gas processing device (6) further comprising at least one auxiliary pumping device (13) configured to reduce the pressure in the at least one exhaust pipe (7), the auxiliary pumping device being located less than 1 m, for example less than 50 cm, from the inlet (9) of the gas processing chamber (26).

Description

[Technical field]

[0001] The present invention relates to a gas treatment device and a vacuum line equipped with this gas treatment device. [Background technology]

[0002] Manufacturing processes in the semiconductor, flat panel display, and solar cell manufacturing industries use process gases that are typically passed through a roughing vacuum pump and then processed by a gas processing system. Some of these manufacturing processes are said to be hazardous because the process gases carried in the vacuum lines are flammable and / or explosive, examples of which include hydrogen, silane, TEOS and hydrides.

[0003] In addition to these dangerous gas species, vacuum lines may also contain deposits of reduced solid species, i.e. non-oxidized solid species such as silicon dust and polysilane polymers. These deposits can build up over time and promote the emergence of further hazardous conditions. Some non-oxidized deposits are highly flammable. They can be ignited, especially by strong gas flows from sudden pumping, or simply by venting the lines or vacuum pump by the operator during maintenance. Some explosions can be particularly destructive because of the extremely large amounts of energy released. This is especially the case in chain explosions, where an initial explosion is initiated by combustible gases that stir up deposits of reduced solid species potentially present in the tube, and these combustible solid deposits are stirred up by the shock wave from the explosion and in turn explode in a "super explosion". Therefore, the risk of personal injury and damage to production equipment is extremely high. Summary of the Invention [Problem to be solved by the invention]

[0004] The current approach to this problem is to continuously dilute the pumped gas with a neutral gas, usually nitrogen, whose flow rate is determined with a safety margin to accommodate the most unfavourable pumping conditions.

[0005] However, this solution has many drawbacks. First, the supply of large volumes of nitrogen gas in the vacuum lines incurs additional costs associated with this gas consumption, and also incurs the energy consumption of vacuum pumps, heating equipment, and gas handling equipment to handle the large volumes of diluent gas flow. Furthermore, cooling of the vacuum lines caused by gas dilution leads to other drawbacks, especially the cost and risk of failure of heating elements. The supply of this large amount of neutral gas also requires overrating of the gas handling equipment and roughing pumping equipment. The diluted nitrogen is further treated in the gas treatment device to produce nitrogen oxides, such as NO2, or "NO X These nitrogen oxides are toxic and constitute air pollutants that must be treated. Finally, it has been observed that in some recent manufacturing processes, the increase in dilution gas is becoming insufficient due to insufficient pumping capacity of the vacuum pump or insufficient processing capacity of the gas handling equipment, so that this solution is reaching its limits. In these extreme operating conditions, problems may arise regarding the reliability of the vacuum pump or the gas handling equipment.

[0006] Another solution is to reduce the temperature of the tubes and vacuum pumps, especially to prevent thermal decomposition of the precursors and to minimize chemical reactions, but it is also important to maintain a high temperature to prevent the risk of condensation deposition.

[0007] Another problem is the trend in some manufacturing processes, especially in the semiconductor industry, to use more and more unstable precursors. The substrate patterns are becoming thinner and thinner, i.e. the substrates have many layers produced in many process steps. To lower the thermal budget, which risks damaging the chips on the substrate, a new generation of molecules is being used that decompose at lower temperatures. The drawback is that these molecules easily deposit in the vacuum lines, which can lead to significant deposits.

[0008] Additionally, some of the spent condensable gas species may solidify into solid by-products and deposit, especially in the form of layers, on moving or static parts of the vacuum pump or tubing, which may lead to clogging of the vacuum lines.

[0009] One object of the present invention is to increase the safety of pumping equipment and vacuum lines conveying flammable and / or explosive gases. Another object of the present invention is to reduce the presence of deposits of condensable species or to retard or minimize the decomposition of precursors that decompose at low temperatures in exhaust lines and pumping equipment. [Means for solving the problem]

[0010] to this end, The present invention relates to a gas processing apparatus configured to process gas at atmospheric pressure pumped by at least one roughing pumping apparatus, The gas treatment device comprises: a gas processing chamber; and at least one exhaust pipe configured to connect an outlet of the at least one roughing pump device to an inlet of the gas processing chamber; Further, the gas processing apparatus may include at least one auxiliary pumping device configured to reduce pressure in the at least one exhaust pipe, the auxiliary pumping device being located less than 1 m, e.g., less than 50 cm, from an inlet of the gas processing chamber.

[0011] Reducing the pressure in the exhaust pipe makes the vacuum line safe. At the same time, it prevents the deposition of condensable species in the exhaust pipe and the pumping equipment. This allows the heating temperature of the vacuum line to be reduced. Reducing the heating temperature of the vacuum line prevents pyrolysis, which reduces the reaction rate of the conversion of precursors and chemical activity in the pumping equipment, reducing undesirable reactions. Reducing the heating temperature also helps to maintain the quality of the lubricant and improve the reliability of the mechanical parts of the pumping equipment, especially the bearings. Thus, the intervals between maintenance operations can be extended. Furthermore, reducing the pressure in the exhaust pipe makes it possible to limit the consumption of dilution gas, which in turn makes it possible to reduce the energy consumption of the pumping and gas treatment equipment and to minimize or even eliminate the formation of nitrogen oxides in the treatment equipment. Reducing the pressure in the vacuum lines also reduces the pressure in the roughing pumping system, allowing the size of the roughing pumping system to be reduced and for the use of weaker and therefore less expensive materials.

[0012] The gas treatment device may further include one or more of the features described below, either alone or in combination. The auxiliary pumping device may be mounted to the gas processing chamber. The auxiliary pumping system may include a venturi gas jet pump mounted to a head of a burner in the gas treatment chamber.

[0013] The gas processing device may include at least one bypass device interposed between the exhaust pipe and the auxiliary pump device, the bypass device comprising: an inlet port connected to the exhaust pipe; a first outlet port connected to the auxiliary pumping device which is connected to the gas processing chamber; a second outlet port configured to bypass the gas processing chamber; and A control member configured to place the inlet port in communication with either the first outlet port or the second outlet port. The bypass device may be a controllable three-way valve.

[0014] If the gas treatment apparatus includes at least two of the bypass devices, the first outlet ports of which are connected to the gas treatment chamber via the auxiliary pump device, the gas treatment apparatus further comprises: at least two isolation valves disposed at respective outlets of the roughing pump arrangement; a processing unit connected to the isolation valve and connected to a first pressure sensor disposed at an outlet of each of a plurality of roughing pump devices downstream of the isolation valve; The processing unit is configured to control all shut-off valves except one of the shut-off valves to be closed for a predetermined period of time in order to issue an alarm when a measurement value from a first pressure sensor in one of the exhaust pipes in which the shut-off valve is open exceeds a predetermined threshold. The gas processing device may include at least one additional auxiliary pump device connected to at least one second outlet port of the bypass device and configured to reduce pressure at the second outlet port.

[0015] The gas treatment device may include: a second pressure sensor configured to measure pressure in the second outlet port; and A processing unit coupled to the second pressure sensor and configured to generate an alarm when a pressure measurement exceeds a predetermined threshold. The gas processing device may include at least one neutral gas injection device configured to inject a neutral gas into the additional auxiliary pumping device and / or to an outlet of the additional auxiliary pumping device.

[0016] The gas processing device may include one processing unit configured to control a pump speed of the additional auxiliary pump device. the pump speed is a first speed in the absence of the control member connecting the inlet port to the second outlet port; When the at least one control member places the inlet port in communication with the second outlet port, a second speed is achieved, the second speed being greater than the first speed. The gas processing device may include one processing unit configured to control a pump speed of the additional auxiliary pump device. the pump speed is a first speed when at least one measurement value from a first pressure sensor at an outlet of the roughing pump device is equal to or less than a threshold value; If the measurement exceeds a threshold, then the speed is changed to a second speed, the second speed being faster than the first speed. The gas processing device may include one processing unit configured to control a pump speed of the additional auxiliary pump device. the pump speed is at a first speed when a concentration of a flammable gas or a deposit causing gas is below a predetermined threshold; When the concentration of flammable or deposit causing gas exceeds the threshold, a second rate is initiated, the second rate being greater than the first rate.

[0017] The auxiliary pumping device and / or the further auxiliary pumping device may comprise a water jet pump and / or a venturi gas jet pump and / or a liquid ring pump and / or a dry vacuum pump and / or a vane pump. The gas treatment chamber may include a burner, and / or an electrical system, and / or a plasma, and / or a scrubber, and / or a chemisorptive and / or physisorptive cartridge. The auxiliary pumping arrangement may include a venturi gas jet pump, the drive gas of which includes a fuel and / or a combustible agent and / or a neutral gas. The venturi gas jet pump may include a heating element configured to heat the drive gas. The vacuum line may include a bypass conduit configured to bypass the auxiliary pumping device and / or the additional auxiliary pumping device in the event of overpressure. The invention also relates to a vacuum line including a gas treatment device as described above. Further characteristics and advantages of the invention will become apparent from the following description, given by way of non-limiting example with reference to the attached drawings, in which: [Brief description of the drawings]

[0018] [Figure 1] 1 is a schematic diagram of an example production facility showing only those components necessary to understand the present invention; [Figure 2A] FIG. 2 is a schematic diagram of one variation of the vacuum line of the present invention. [Figure 2B] FIG. 4 is a schematic diagram of another variant of the vacuum line of the present invention. [Figure 2C] FIG. 4 is a schematic diagram of another variant of the vacuum line of the present invention. [Figure 2D] FIG. 2 is a schematic diagram of another example of a vacuum line of the present invention. [Figure 2E] FIG. 4 is a schematic diagram of another example of a vacuum line of the present invention. [Diagram 3] 1 is a graph showing the explosion pressure P (in mbar) as a function of the hydrogen concentration C. (The symbols represent the measured values, the solid line represents the theoretical values.) [Figure 4] FIG. 4 is a schematic diagram of another example of a vacuum line of the present invention. [Diagram 5] FIG. 4 is a schematic diagram of another example of a vacuum line of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] In each figure, identical elements are given the same reference numbers. The following embodiments are exemplary. Although the following description refers to one or more embodiments, this does not necessarily mean that each reference relates to the same embodiment or that a feature applies only to a single embodiment. Individual features of different embodiments can be combined or interchanged to provide other embodiments. Roughing vacuum pump refers to a positive displacement vacuum pump configured to suck, transport, and exhaust gas at atmospheric pressure. The rotor of the roughing vacuum pump can be of the Roots, claw, screw, vane, or scroll type. The roughing vacuum pump is configured to be able to start at atmospheric pressure.

[0020] A positive displacement vacuum pump configured to take in, transport and exhaust the gas to be pumped using two Roots rotors is defined as a Roots or Roots blower vacuum pump. The Roots vacuum pump is placed in series upstream of the roughing vacuum pump. The rotors are carried by two shafts that are rotated by the Roots vacuum pump motor. Roots vacuum pumps differ from roughing vacuum pumps primarily by the larger dimensions of their exhaust stage due to their higher pumping capacity and larger tolerances, and by the fact that Roots vacuum pumps cannot exhaust at atmospheric pressure and therefore must be installed in series upstream of a roughing vacuum pump. An "upstream" component is defined as a component that is disposed ahead of another component with respect to the direction of flow of the pumped gas, in contrast to a "downstream" component that is disposed aft with respect to the direction of flow of the pumped gas.

[0021] FIG. 1 is a schematic diagram of an example production facility, showing only the components necessary for understanding the present invention. The production facility 1 includes a semiconductor manufacturing tool 2 having one or more process chambers 3 connected to one or more vacuum lines 4. The process chambers 3 are suitable for receiving one or more substrates, such as semiconductor wafers, flat panel displays, or photovoltaic panels. One vacuum line 4 includes one or more pumping devices 5 connected to at least one process chamber 3 and one or more gas processing devices 6, which include one or more exhaust pipes 7 connecting an outlet 8 of at least one roughing pumping device 10 to an inlet 9 of a gas processing chamber 26 of the gas processing device 6. In the embodiment of FIG. 1, one semiconductor manufacturing apparatus 2 is shown, and its process chamber 3 is connected to the vacuum line 4. The exhaust pipe 7 can have a variable length. Between the outlet of the roughing pumping device 10 and the inlet 9 of the gas processing chamber 26, the exhaust pipe has a length of 1 to 4 m.

[0022] The pumping arrangement 5 comprises at least one roughing pumping arrangement 10, which is configured to discharge the pumped gas at the outlet 8 at atmospheric pressure or at a pressure higher than atmospheric pressure, in particular even up to 1,200 mbar (120,000 Pa). The roughing pumping arrangement 10 can also discharge the pumped gas at a pressure lower than atmospheric pressure. The pumping arrangement 5 may also include at least one high vacuum pumping arrangement disposed in series upstream of the roughing pumping arrangement 10 in the direction of flow of the pumped gas, interposed between the process chamber 3 and the roughing pumping arrangement 10. The high vacuum pumping arrangement may include a Roots vacuum pump 11 and / or a turbomolecular vacuum pump 12. Gas processing chamber 26 is configured to process gases pumped by roughing pumping system 10 at atmospheric pressure.

[0023] The gas treatment chamber 26 contains, in a manner known per se, a burner 23 configured to generate a thermal reaction at high temperature, for example by combustion of hydrocarbons, and / or an electrical system configured to generate a thermal reaction at high temperature by means of heating resistors, and / or a plasma, and / or a scrubber, and / or a chemisorptive and / or physisorptive cartridge.

[0024] According to an exemplary embodiment shown in FIG. 1, the gas treatment chamber 26 includes a burner 23 and a scrubber 24 arranged in series downstream of the burner 23 in the gas flow direction. The burner 23 can be a combustion burner, an electric burner or a plasma burner. A reactive gas such as oxygen or air is added to the pumped gas and heated to very high temperatures by the burner 23 to activate the formation of new chemically reactive soluble species, which are then captured by the scrubber 24. A mist can be generated in the burner 23 by a water injection nozzle (also commonly known as a quench nozzle) to rapidly cool the gas and interrupt the chemical equilibrium, rather than allowing the dissociated hot gases to recombine with each other and to counter-equilibrate. The scrubber 24 comprises, for example, a packed column in which the pumped gas rises countercurrent to the water flow. At the outlet 31 of the gas treatment device 6, the gas can be discharged to the atmosphere or to a central scrubber of the production plant.

[0025] The gas treatment device 6 further comprises at least one auxiliary pumping device 13 configured to reduce the pressure in the at least one exhaust line 7 (see Figures 1, 4 and 5). This auxiliary pumping device 13 can be of any type, including, for example, a water jet pump (or water blast) as shown in Figure 1, and / or a Venturi gas jet pump, and / or a liquid ring pump, and / or a dry vacuum pump such as Roots type, Claw type, and / or a screw vacuum pump, and / or a vane type and / or a scroll type and / or a membrane or diaphragm type pump. If the auxiliary pumping device 13 comprises a venturi gas jet pump, the driving gas injected to cause the pressure drop can comprise a neutral gas, such as nitrogen. Said driving gas then contributes to further dilution of the pumped gas coming from the exhaust pipe 7. This driving gas can comprise a fuel and / or a fuel agent, such as methane. The driving gas also contributes to further dilution of the pumped gas coming from the exhaust pipe 7, without reducing the efficiency of the burner 23 of the gas treatment device 6 and without generating nitrogen oxides.

[0026] The venturi gas jet pump may include a heating element configured to heat the drive gas. The drive gas may be heated to a temperature above 50° C., for example to 500° C. or higher. Heating the drive gas may improve the efficiency of the burner 23 of the gas treatment device 6 and prevent powder build-up at the jet pump outlet. The drive gas may be heated, for example, by a heat exchanger in contact with the gas treatment chamber 26 or a hot part of the pump device 5, which may allow for reduced power consumption.

[0027] The gas jet pump has the advantage that it does not consume any power, it is compact and lightweight and can therefore be easily integrated into the pumping device 5 or gassing device 6 (see FIG. 2A). If the auxiliary pumping arrangement 13 comprises a dry vacuum pump, the purge gas of the auxiliary vacuum pump 13 may comprise a neutral gas, such as nitrogen, and / or a fuel, such as methane, and / or a combustible agent. The purge gas may be further heated to a temperature greater than 50° C., such as greater than 500° C., for example, by a heat exchanger in contact with a hot portion of the gas treatment chamber 26 or the pumping arrangement 5. At least one auxiliary pumping device 13 is located at the inlet 9 of the gas treatment chamber 26, i.e. at a distance of less than 1 m, for example less than 50 cm. This is generally because the inlet 9 of the burner is generally located more than 1.50 m above the ground, so that the auxiliary pumping device 13 must be located above it.

[0028] In general, the pumping capacity of the auxiliary pumping device 13 is preferably smaller than the pumping capacity of the roughing pumping device 10, for example, 5 m 3 / h and / or 100m 3 / h. In these conditions, the auxiliary pumping device 13, which in particular comprises a dry vacuum pump or a liquid ring pump or a vane pump, is sufficiently light to be placed as close as possible to the inlet 9 of the gas treatment chamber 26 (see FIG. 2A) and, for example, even inside the gas treatment chamber 26 (see FIG. 2B), without any risk and without requiring special handling measures. An auxiliary pumping device 13 of the Venturi gas jet pump type is, for example, mounted at the head of a burner 23 of the gas treatment device 6 (see FIG. 2B). In this case, a single auxiliary pumping device 13 mounted in the gas treatment chamber 26 makes it possible to reduce the pressure in several exhaust pipes 7 (see FIG. 5). The fuel, which is the combustible agent of the driving gas, then becomes the gas that supplies the flame to the burner.

[0029] The vacuum line 4 may further include at least one bypass line 14 configured to bypass the auxiliary pumping device 13 and / or the additional auxiliary pumping device 27, as will be seen below, in the event of overpressure (see Figures 2C, 4, 5). The bypass line 14 includes a line bypassing the auxiliary pumping device 13 or the additional auxiliary pumping device 27 and a controllable valve or check valve arranged in the line and configured to open or close depending on the pressure difference across the check valve / valve. The bypass line 14 allows bypassing the auxiliary pumping device 13 or the additional auxiliary pumping device 27 to prevent possible pumping capacity limitations caused by the auxiliary pumping device 13 or the additional auxiliary pumping device 27, especially in the case of pumping strong gas flows or in the case of a failure of the auxiliary pumping device. The bypass line 14 can also bypass the gas treatment device 6 (see FIG. 2D), but only while discharging large volumes of air at atmospheric pressure without dangerous gas species. In this case, the bypass line 14 is provided with a controllable valve that is normally open, i.e. open in the absence of a signal or in the event of a fault. This valve can be controlled to close only by a dry contact coming from the process chamber 3 when no process gas is introduced into this process chamber.

[0030] If the auxiliary vacuum pump 13 and / or the additional auxiliary pumping device 27 comprises a venturi gas jet pump, this can be integrated into a check valve in the bypass pipe 14 (see FIG. 2E). A movable shutter of this check valve has a venturi through passage. This check valve can adopt a closed position, in which the check valve forms a jet pump of the auxiliary vacuum pump 13 or the additional auxiliary pumping device 27 when a drive gas is injected at the inlet of the venturi passage. The check valve can also adopt an open position in which pumped gas bypasses the venturi through-passage when the pressure differential on either side of the check valve is greater than the check valve's load threshold.

[0031] Returning to FIG. 1, the vacuum line 4 further includes a dilution gas injection device 15, a first pressure sensor 16 configured to measure the pressure in the exhaust pipe 7, and a control unit 17 connected to the first pressure sensor 16. The diluent gas injection device 15 is configured to inject a diluent gas, such as a neutral gas, such as nitrogen, into the exhaust line 7 and / or into the roughing pumping device 10 and / or into the backing pumping device 13. The diluent gas is injected, for example, at the inlet and / or outlet 8 of the roughing pumping device 10 and / or into the last two pumping stages of a multi-stage roughing vacuum pump of the roughing pumping device 10.

[0032] The first pressure sensor 16 is disposed, for example, near the outlet 8 of the roughing pump device 10 . The control unit 17 includes a controller, a microcontroller, a memory and a computer program capable of implementing the method for controlling the vacuum lines. This control unit is, for example, a computer or a programmable logic controller. The control unit 17 can be configured to control the auxiliary pumping device 13 and the diluent gas injection device 15 according to a first operating mode or a second operating mode as a function of the pressure measured by the first pressure sensor 16 . In the first operating mode, the pressure in the exhaust pipe 7 is maintained below 200 mbar (20,000 Pa).

[0033] The auxiliary pumping device 13, capable of reducing the pressure in the exhaust line 7, can be controlled to pump continuously or intermittently. For example, the auxiliary pumping arrangement 13 includes a venturi gas jet pump, and the control unit 17 is configured to control the drive gas of the jet pump to reduce pressure.

[0034] According to another example, the auxiliary pumping device 13 comprises a water jet pump, the control unit 17 being configured to control the driving fluid of the water jet pump making it possible to reduce the pressure (see FIG. 1). In this case, according to an embodiment, the auxiliary pumping device 13 further comprises a fluid pump 19, the outlet of which is arranged to be controlled by the control unit 17 in order to supply the water jet pump with driving liquid. The inlet of the fluid pump 19 is arranged, for example, in communication with the liquid of a washing tank 22 in a washing tower 24 of the gas treatment device 6. The gas treatment device 6 can then comprise a gas / water separator 20, which is interposed between the water jet pump of the auxiliary pumping device 13 and the inlet 9 of the burner 23 of the gas treatment device 6. The liquid residue can be discharged via a plunger tube 21 into the washing tank 22. Thus, in the first operating mode, which is the optimum operating mode, by default the pressure in the exhaust pipe is maintained below the ignition condition of most of the combustible gases carried in the exhaust pipe 7.

[0035] This can be better understood with reference to the example of FIG. Figure 3 plots the explosion pressure P in millibars as a function of the concentration of hydrogen (fraction in air) for various values ​​of the initial pressure before the explosion. (The symbols represent the measured values, the solid line represents the theoretical values.) The white triangles are 100mbar (10,000Pa), the white squares are 150mbar (15,000Pa), the white diamonds are 200mbar (20,000Pa), the black circles are 300mbar (30,000Pa), the black triangles are 500mbar (50,000Pa), the black squares are 750mbar (75,000Pa), and the black diamonds are 1,000mbar (100,000Pa). According to FIG. 3, for hydrogen gas pressures of 100 mbar (10,000 Pa), 150 mbar (15,000 Pa) and 200 mbar (20,000 Pa), the explosion pressure under stoichiometric conditions, i.e. the explosion pressure that may lead to the most severe explosion, remains below 1,600 mbar (160,000 Pa). In this way, a set of safe conditions capable of preventing gas explosions is established in the roughing pumping arrangement 10 and the exhaust line 7. It is believed that for pressures below 200 mbar (20,000 Pa) in the exhaust line, the pressure generated by ignition under stoichiometric conditions (also called explosion pressure) can be easily contained, i.e. will not cause significant mechanical damage to the pumping arrangement 5 or the piping.

[0036] Although Figure 3 is for the specific case of hydrogen gas, the same behavior is observed for all flammable gases: the explosion pressure under stoichiometric conditions, i.e. the explosion pressure that can lead to the most severe explosion, remains below 1,600 mbar (160,000 Pa).

[0037] Furthermore, in the first operating mode, there is no need to inject dilution gas to be outside the range of flammable and / or explosive conditions, since safety is ensured by the vacuum level of pressure below 200 mbar (20,000 Pa). Therefore, the control unit 17 can control to stop the injection of dilution gas into the exhaust pipe 7 or the pumping device 5. The control unit 17 may also be configured to stop the injection of purge gas into the roughing pump arrangement 10 in the first mode of operation, making it easier to maintain a low pressure in the exhaust line 7.

[0038] The control unit 17 is configured to switch to the second operating mode if the pressure in the exhaust pipe cannot be reduced below 200 mbar (20,000 Pa). In this second operating mode, the pressure in the exhaust pipe 7 is greater than 20,000 Pa. The control unit 17 is further configured to control the injection of diluent gas into the exhaust pipe 7 or into the pumping device 5 by the diluent gas injection device 15. This second mode of operation can be considered a "degraded" mode of operation, where the flammability risk can be controlled by dilution. The control unit 17 can be configured such that in the second operating mode the flow rate of dilution gas introduced into the gas flow of the exhaust pipe 7 or the pumping device 5 is determined as a function of the pressure in the exhaust pipe measured by the first pressure sensor 16 and as a function of information about the flammable gas being pumped, so that the pressure generated by ignition (or explosion pressure) remains below 160,000 Pa (1,600 mbar), in particular under stoichiometric conditions, i.e. even under the worst flammable gas concentration conditions.

[0039] For example, referring to Fig. 3, when the initial pressure before the explosion measured by the first pressure sensor 16 is 300 mbar (30,000 Pa) (black circle), the [H2] concentration of 32% under stoichiometric conditions needs to be reduced to the target [H2] concentration. That is, in order to prevent the pressure in the exhaust pipe from exceeding the explosion pressure of 1,600 mbar (160,000 Pa), the [H2] concentration needs to be reduced to 15% by dilution with neutral gas. According to another example in FIG. 3, when the pressure in the exhaust pipe measured by the first pressure sensor 16 is 500 mbar (50,000 Pa) (black triangles), in order to keep the pressure in the exhaust pipe at 1,600 mbar (160,000 Pa), which is below the explosion threshold, the concentration under stoichiometric conditions must be reduced to 6-7% by dilution. The concentration of the flammable gas before dilution is determined in advance by the user based on the value of the maximum flow rate of the flammable gas introduced into the process chamber 3.

[0040] When multiple combustible gases are present, the dilution ratio of the neutral gas is determined based on the maximum flow rate of the combustible gases injected simultaneously into the process chamber 3. More specifically, the dilution ratio is first determined separately for each combustible gas using a data table specific for each gas, as shown by the graph in Fig. 3, as a function of the pressure in the exhaust pipe measured by the first pressure sensor 16. The data tables can be stored in the control unit 17. The diluted target concentration (to be obtained) of each gas is then recalculated for all combustible gases simultaneously introduced into the process chamber 3. All simultaneously injected gases mutually contribute to the reduction of their respective concentrations.

[0041] The dilution rate is therefore adjusted as a function of the amount (or flow rate, pressure) of flammable / explosive gas so that the pressure in the exhaust pipe (or explosion pressure) generated by ignition is kept below 160,000 Pa (1,600 mbar). Furthermore, the dilution gas may include a fuel and / or a neutral gas. The control unit 17 may be configured to determine the amount and proportion of fuel and neutral gas in the dilution gas as a function of information about the combustible gas introduced into the process chamber 3, such as a recipe. For example, in the case of a recipe that alternates between deposition steps with a TEOS precursor gas and cleaning steps with NF3 gas, the control unit 17, having access to this information, can increase the amount of fuel injected during deposition, which can facilitate the conversion of TEOS residues to soluble species. This information can also be used to control the flame temperature of the burner 23. The control unit 17 may further be configured to control the injection of a high flow rate of dilution gas into the exhaust line 7 and / or into the pumping device 5 if the measured pressure exceeds 500 mbar. This high flow rate of dilution gas may be preferentially injected into the pumping device 5 and possibly also into the exhaust line 7 at the same time.

[0042] The value of the high flow rate of the dilution gas is, for example, predetermined as a function of the maximum flow rate of the flammable gas that can be injected into the process chamber 3. This information is predetermined by a user based on the value of the maximum flow rate of the flammable gas introduced into the process chamber. The high flow rate of the dilution gas is, for example, predetermined so that the flammable gas concentration is less than 25% of the lower explosion limit (LEL). Thus, for example, in addition to being a function of the worst-case conditions of the recipe implemented in process chamber 3, the safety margin provided by 25% of the LEL ensures safety even in the most adverse pumping conditions. This is an emergency mode of operation that is occasionally used in extreme situations. In the prior art, the equivalent of this emergency mode of operation is permanently implemented, resulting in excessive nitrogen consumption. Thus, maximum dilution in this embodiment is implemented on an irregular basis, which saves on dilution gas consumption and energy budget.

[0043] Referring to FIG. 3, if the hydrogen pressure exceeds 500 mbar (50,000 Pa), the concentration of hydrogen [H2] may decrease in the exhaust pipe 7 to a value below 1%, i.e., below 25% of the explosive limit (LEL) as recommended by the prior art. Thus, in the first operating mode, the control unit 17 maintains the pressure in the exhaust pipe 7 below 200 mbar (20,000 Pa). If the pressure measured in the exhaust pipe 7 remains below 200 mbar (20,000 Pa), the control unit remains in the first operating mode. If it is not possible to maintain a pressure below 200 mbar (20,000 Pa) in the auxiliary pumping device 13, particularly if the capacity of the auxiliary pumping device 13 is insufficient to maintain this pressure, the control unit switches to the second operating mode.

[0044] In the second operating mode, the control unit 17 controls the injection of dilution gas into the exhaust pipe 7 or into the pumping device 5 . For pressures between 200 mbar (20,000 Pa) and 500 mbar (50,000 Pa), the flow rate of dilution gas injected into the exhaust line 7 or into the pumping device 5 can be determined as a function of the exhaust line pressure measured by the first pressure sensor 16 or as a function of information about the combustible gas introduced into the process chamber 3. This ensures that the explosion pressure remains below 1,600 mbar (160,000 Pa) even under the most severe explosion conditions, such as stoichiometric conditions.

[0045] The pressure in the exhaust pipe 7 is therefore firstly governed by the capacity of the auxiliary pump device 13 and then, if the pressure measured in the exhaust pipe 7 is greater than 200 mbar (20,000 Pa) and less than 500 mbar (50,000 Pa), as a function of the pressure measured in the exhaust pipe 7 and by information regarding the combustible gas introduced into the process chamber 3. If, in the second operating mode, the measured pressure in the exhaust pipe returns to below 200 mbar (20,000 Pa), the control unit reverts to the first operating mode. If the exhaust line pressure exceeds 500 mbar (50,000 Pa), a dilution gas can be injected, for example, directly into the roughing pump arrangement 10 at a predetermined high flow rate value plus a safety margin to make it safe under the most adverse pumping conditions.

[0046] It will be seen from the above that reducing the pressure in the exhaust line 7 makes it possible to limit the injection of diluent gas only to the most dangerous situations. At the same time as making the vacuum line 4 safe, reducing the exhaust line pressure prevents the deposition of condensable species in the exhaust line 7, and therefore reduces the heating requirements of the vacuum line. Furthermore, reducing the heating requirements of the vacuum line also makes it possible to avoid pyrolysis and therefore reduce the conversion of heat-sensitive precursors in the pumping device 5. This combination of low pressure and low temperature also makes it possible to reduce the kinetics of chemical activity, thereby reducing undesirable chemical reactions, whether they are corrosive or potentially clogging, to the components of the discharge line 4. The reduced heating requirements also make it possible to maintain the quality of the lubricant and to improve the reliability of the mechanical parts of the pumping device 5, especially the bearings. Thus, the intervals between maintenance operations can be significantly extended, which improves the economic profitability of the discharge line 4 and the uptime of the production facility. Furthermore, from an economic point of view, the use of expensive precious metals can be reduced. The components of the roughing vacuum pumping apparatus 10 can be standardized both in terms of design and material, which simplifies and makes the provision of the components of the roughing vacuum pumping apparatus universal.

[0047] Furthermore, the consumption of dilution gas is limited, which also makes it possible to reduce the energy consumption of the pumping device 5, and at the same time reduces the energy consumption of the gas treatment device 6 and minimizes or even eliminates the formation of nitrogen oxides in the gas treatment device 6.

[0048] According to the exemplary embodiment shown in FIG. 1, the gas treatment device 6 may also include at least one bypass device 25 interposed between the exhaust pipe 7 and the auxiliary pump device 13 . The bypass device 25 includes an inlet port 25a connected to the exhaust pipe 7, a first outlet port 25b connected to the auxiliary pump device 13 and further connected to the processing chamber 26, a second outlet port 25c configured to bypass the processing chamber 26, and a control member configured to communicate the inlet port 25a with the first outlet port 25b or the second outlet port 25c. The bypass device 25 is, for example, a controllable three-way valve. This bypass device 25 allows the pumped gas to be bypassed via the second outlet port 25c around the auxiliary pumping device 13 and the treatment chamber 26 only if it does not need to be treated, thus allowing the pumped gas to be directed to a central wash tower in the production plant.

[0049] The control member can be a manual member that a maintenance operator can manipulate during maintenance to, for example, divert gas from the process chamber 26 during maintenance operations on the chamber. In this way, for example in the event of a failure or maintenance of the burner 23, the pumped gas can be redirected by the bypass device 25. The control member can select the first or second outlet port 25b, 25c depending on an item of information from the process chamber 3, such as the state of the process chamber 3 (processing, stopped or waiting) or an item of information indicating whether gas needs to be processed or not. For example, gas coming from a stopped or waiting process chamber 3 cannot be processed and therefore bypasses the burner 23 via the bypass device 25. Information such as dry contact or air pressure control can directly control the switching of the control member.

[0050] For example, there is one bypass device 25 for each process chamber 3 , and there are several process chambers 3 for each manufacturing apparatus 2 . Furthermore, multiple process chambers 3, and therefore multiple bypass devices 25, can be connected to a single processing chamber 26 (see FIG. 4). Furthermore, the second outlet ports 25c of the multiple bypass devices 25 may be coupled to one common pipe 35.

[0051] The gas treatment device 6 may further include at least one additional auxiliary pump device 27 connected to at least one second outlet port 25c of the bypass device 25 and configured to reduce the pressure in said second outlet port 25c. Reducing the pressure in the second outlet port 25c allows the rate of chemical reactions to be reduced, limiting corrosion. Furthermore, the pressure is removed from explosive and flammable conditions of the gas. Less maintenance is required due to reduced deposits.

[0052] The additional auxiliary pumping device 27 can be of any type: it can be, for example, a water jet pump and / or a Venturi gas jet pump and / or a liquid ring pump, or it can be a vacuum pump of the Roots, claw and / or screw type, and / or a vane and / or scroll and / or membrane or diaphragm type pump. An outlet 30 of the additional auxiliary pumping device 27 is coupled, for example, to an outlet 31 of the treatment chamber 26 for conveying the gas to a central scrubber.

[0053] The gassing device 6 may include one processing unit 32, which may include a controller, a microcontroller, a memory and a computer program, such as a computer or a programmable logic controller, which may be the same unit as the control unit 17 of the vacuum line 4. According to an exemplary embodiment, the gas treatment device 6 includes a second pressure sensor 28 configured to measure the pressure in the second outlet port 25c. The processing unit 32 can be connected to the second pressure sensor 28 and can be configured to generate an alarm when a measurement value from the second pressure sensor 28 exceeds a predetermined threshold. The predetermined threshold value is, for example, a measurement value from the second pressure sensor 28 at optimal operating conditions, which is obtained, for example, immediately after a cleaning maintenance. Exceeding this threshold value may reflect an abnormal increase in the pressure in the second outlet port 25c, for example due to a clogged pipe and / or the presence of a leak in the pipe.

[0054] Similarly, the processing unit 32 may be connected to a first pressure sensor 16 at the outlet 8 of the roughing pump apparatus 10 and may be configured to issue an alarm if the measured value from the first pressure sensor 16 exceeds a predetermined threshold value in order to prevent clogging and / or leakage of the exhaust pipe 7 connected to the inlet port 25a. The processing unit 32 is configured to be able to identify one exhaust pipe 7 connected to an inlet port 25a that has a leak or is clogged when several (at least two) bypass devices 25 are connected to the gas processing chamber 26. For this purpose, the gas processing device 6 includes at least two isolation valves 33 arranged at the respective outlets 8 of the roughing pumping devices 10 and connected to the inlet ports 25a, and also includes at least two isolation valves 34 arranged at the respective inlets of the roughing pumping devices 10.

[0055] These isolation valves 33 are normally open, i.e. open in the absence of a signal or in the event of a fault, and are controlled to close only when no process gas is introduced into the process chamber 3. The processing unit 32 is connected to each isolation valve 33, and, if applicable, each isolation valve 34, and to each first pressure sensor 16 at each outlet 8 of each roughing pump arrangement 10. Each first pressure sensor 16 is disposed downstream of a respective isolation valve 33. In the normal mode of operation, each isolation valve 33, 34 is open. In diagnostic mode, the processing unit 32 controls all isolation valves 33 to be closed for a predetermined period of time, for example on the order of a few minutes, except for the isolation valve on the particular exhaust pipe 7 whose integrity is being checked. The processing unit 32 may also control the closing of the upstream isolation valve 34 and / or the shutting down of the roughing pumping system 10 and / or the shutting down of the supply of purge gas to the roughing pumping system 10 . The processing unit 32 compares the measurement value from the first pressure sensor 16 of one exhaust pipe 7 whose isolation valve 33 is open with a predefined threshold value. As mentioned above, this predefined threshold value is based on measurements from the first pressure sensor 16 obtained in the same operating conditions, for example after cleaning maintenance. If the measurement value from the first pressure sensor 16 exceeds the predefined threshold value, the processing unit 32 issues an alarm. The test is then repeated for each remaining exhaust pipe 7. It is thus possible to identify whether one of the several exhaust pipes 7 is faulty.

[0056] According to one embodiment, the gas treatment device 6 includes at least one neutral gas injector 29 configured to inject a neutral gas, such as nitrogen, into the additional auxiliary pumping device 27 and / or into the outlet 30 of the additional auxiliary pumping device 27. The neutral gas can dilute the pumped gas, moving it away from flammable or explosive conditions. This neutral gas can be heated before injection to 50° C. or more, for example 500° C. or more, for example by a heat exchanger in contact with a hot part of the gas treatment chamber 26. For example, if the additional auxiliary pumping device 27 comprises a dry vacuum pump, the neutral gas injection device 29 can be formed by the purge gas of the dry vacuum pump. If the additional auxiliary pumping device 27 comprises a Venturi gas jet pump, the neutral gas injection device 29 can be formed by the drive gas. The additional auxiliary pumping device 27 can operate continuously.

[0057] According to another embodiment, provision is made for starting up the additional auxiliary pumping device 27, for example by putting at least one inlet port 25a of the plurality of control members of the bypass device 25 in communication with the second outlet port 25c to bypass the gas treatment chamber 26, and / or as a function of measurements of the second pressure sensor 28 and / or of a combustible gas sensor arranged in a common pipe 35 connected to the second outlet port 25c, and / or of items of information coming from the process chamber 3. The processing unit 32 can be configured to control the pump speed of the additional auxiliary pump device 27 as a function of the number of multiple bypass devices 25 that communicate the inlet port 25a with a common pipe 35 connected to the second outlet port 25c. The pump speed includes at least two distinct pump speeds, for example a first speed and a second speed, the second speed being faster than the first speed. In the case of an additional auxiliary pumping device 27 for a dry vacuum pump, the second pumping speed is for example at least 20% faster, or at least 50% faster than the rotational speed determining the first pumping speed. This configuration may conserve energy (or drive gas in the case of a jet pump) when little pumped gas passes through the at least one second outlet port 25c.

[0058] The processing unit 32 is configured, for example, to control the pump speed to a first speed when the control member does not connect the inlet port 25a to the second outlet port 25c, and to control the pump speed to a second speed when the at least one control member connects the inlet port 25a to the second outlet port 25c.

[0059] According to another example, the processing unit 32 can be configured to control the pump speed of the additional auxiliary pump device 27 to a first speed when at least one measurement value from the first pressure sensor 16 at the outlet 8 of the roughing pump device 10 is below a predetermined threshold, and to switch to a second speed when the measurement value exceeds the threshold. According to another example, the processing unit 32 is configured to control the pump speed of the additional auxiliary pumping device 27 to a first speed when the concentration of the flammable gas or deposit-causing gas is below a predefined threshold, and to a second speed higher than the first speed when the concentration of the flammable gas or deposit-causing gas exceeds the threshold.

[0060] The concentration of the flammable gas or the deposit-causing gas is obtained, for example, by a gas sensor or by information coming from the process chamber 3, in particular information defined in the process recipe. The processing unit 32 increases the pump speed if the concentration of the flammable gas or the deposit-causing gas increases. [Explanation of symbols]

[0061] 1. Production facilities 2. Semiconductor manufacturing equipment 3. Process chamber 4 Vacuum line (exhaust line) 5. Pumping equipment 6 Gas treatment equipment 7. Exhaust pipe 8 outlet 9 Entrance 10 Roughing vacuum pump unit 11 High vacuum pump equipment (Roots vacuum pump) 12 High vacuum pump equipment (turbomolecular vacuum pump) 13 Auxiliary pump unit 14 Bypass pipe 15 Dilution gas injection device 16 First pressure sensor 17 Control Unit 19 Fluid Pump 20 Gas / Water Separator 21 Plunger tube 22 tanks 23 Burner 24 Washing Tower 25 Bypass device 26 Gas Processing Room 27 Additional auxiliary pump unit 28 Second pressure sensor 29 Neutral gas injection device 30 Outlet of additional auxiliary pump device 31 Gassing chamber exit 32 Processing Unit 33 Isolation valve 34 Isolation valve 35 Common Pipe

Claims

1. A vacuum line (4) including a gas treatment device (6) configured to treat gas pumped by at least one roughing pump device (10) at atmospheric pressure, The gas treatment device (6) comprises a gas treatment chamber (26) and at least one exhaust pipe (7) configured to connect an outlet (8) of the at least one roughing pump device (10) to an inlet (9) of the gas treatment chamber (26); the gas treatment device (6) further comprises at least one auxiliary pumping device (13) configured to reduce the pressure in the at least one exhaust pipe (7), the auxiliary pumping device being located less than 1 m from an inlet (9) of the gas treatment chamber (26); the auxiliary pump device (13) is disposed between the discharge port (8) of the roughing pump device (10) and the inlet (9) of the gas processing chamber (26); The pump capacity of the auxiliary pump device (13) is smaller than the pump capacity of the roughing pump device (10), A vacuum line characterized in that the length of the exhaust pipe (7) between the discharge port (8) of the roughing pump device (10) and the inlet (9) of the gas processing chamber (26) is 1 meter or more.

2. A vacuum line (4) according to claim 1, A vacuum line, characterized in that the length of the exhaust pipe (7) between the outlet (8) of the roughing pump device (10) and the inlet (9) of the gas treatment chamber is between 1 meter and 4 meters.

3. A vacuum line (4) according to claim 1 or 2, at least one bypass device (25) interposed between the exhaust pipe (7) and the auxiliary pump device (13); The bypass device comprises: an inlet port (25a) connected to the exhaust pipe (7); a first outlet port (25b) connected to the auxiliary pump device (13) which is connected to the gas treatment chamber (26); a second outlet port (25c) configured to bypass the gas treatment chamber (26); and 1. A vacuum line comprising: a control member configured to connect said inlet port (25a) to said first outlet port (25b) or said second outlet port (25c).

4. A vacuum line (4) according to claim 3, A vacuum line, characterized in that the bypass device (25) is a controllable three-way valve.

5. A vacuum line (4) according to claim 3 or 4, At least two of said bypass devices (25), Each of the first outlet ports (25b) is connected to one of the gas treatment chambers (26) via one of the auxiliary pump devices (13); Each of the bypass devices is at least two isolation valves (33) disposed at the outlets (8) of each of the roughing pumping devices (10); a processing unit (32) connected to the isolation valve (33) and to a first pressure sensor (16) arranged at the outlet (8) of each of the roughing pump devices (10) downstream of the isolation valve (33); the processing unit (32) is configured to control the closing of all of the isolation valves (33) except for one isolation valve for a predetermined period of time in order to issue an alarm when a measurement value from the first pressure sensor (16) of the exhaust pipe (7) in which the isolation valve (33) is open exceeds a predetermined threshold.

6. A vacuum line (4) according to claim 5, at least one additional auxiliary pump device (27) connected to at least one second outlet port (25c) of the bypass device (25) and configured to reduce the pressure at the second outlet port (25c).

7. A vacuum line (4) according to claim 6, a second pressure sensor (28) configured to measure pressure in the second outlet port (25c); a processing unit (32) connected to the second pressure sensor (28) and configured to generate an alarm when the pressure measurement exceeds a predetermined threshold.

8. A vacuum line (4) according to any one of claims 6 or 7, 1. A vacuum line comprising at least one neutral gas injection device (29) configured to inject a neutral gas into said additional auxiliary pumping device (27) and / or into an outlet (30) of said additional auxiliary pumping device (27).

9. A vacuum line (4) according to any one of claims 6 to 8, one processing unit (32) configured to control the pump speed of said additional auxiliary pump device (27); The pump speed is a first speed when the control member does not communicate the inlet port (25a) with the second outlet port (25c); a second speed when the at least one control member communicates the inlet port (25a) with the second outlet port (25c); The second speed is greater than the first speed.

10. A vacuum line (4) according to any one of claims 6 to 8, one processing unit (32) configured to control the pump speed of said additional auxiliary pump device (27); The pump speed is a first speed when at least one measurement value from the first pressure sensor (16) at the outlet (8) of the roughing pump arrangement (10) is equal to or less than a threshold value; a second speed when the measured value exceeds the threshold value; The second speed is greater than the first speed.

11. A vacuum line (4) according to any one of claims 6 to 8, one processing unit (32) configured to control the pump speed of said additional auxiliary pump device (27); the pump speed is a first speed when a concentration of a flammable gas or a deposit causing gas is equal to or less than a predetermined threshold; a second rate when the concentration of the flammable gas or the deposit-causing gas exceeds the threshold; The second speed is greater than the first speed.

12. A vacuum line (4) according to any one of claims 6 to 11, The vacuum line, characterized in that the additional auxiliary pump device (27) comprises a water jet pump and / or a venturi gas jet pump and / or a liquid ring pump and / or a dry vacuum pump and / or a vane pump.

13. A vacuum line (4) according to any one of claims 6 to 12, A vacuum line comprising a bypass pipe (14) configured to bypass said additional auxiliary pump device (27) in case of overpressure.

14. A vacuum line (4) according to any one of claims 1 to 11, The vacuum line, characterized in that the auxiliary pump device (13) is a water jet pump and / or a venturi gas jet pump and / or a liquid ring pump and / or a dry vacuum pump and / or a vane pump.

15. A vacuum line (4) according to any one of the preceding claims, 1. A vacuum line, characterized in that the gas treatment chamber (26) comprises a burner (23), and / or an electrical system, and / or a plasma, and / or a scrubbing tower (24), and / or a chemisorption and / or physisorption cartridge.

16. A vacuum line (4) according to any one of claims 1 to 11, 11. A vacuum line, characterized in that the auxiliary pumping device (13) comprises a Venturi gas jet pump, the drive gas of which comprises a fuel and / or a combustible agent and / or a neutral gas.

17. A vacuum line (4) according to claim 16, The vacuum line, wherein the venturi gas jet pump includes a heating element configured to heat the drive gas.

18. A vacuum line (4) according to any one of the preceding claims, A vacuum line comprising a bypass pipe (14) arranged to bypass said auxiliary pump device (13) in case of overpressure.

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