Multiple vacuum chamber pumping system and multiple vacuum chamber pumping method

Abstract

A vacuum pumping system and method for evacuating multiple chambers is disclosed. The vacuum pumping system includes a plurality of branch process gas lines within a clean room, each configured to connect to a corresponding chamber, a shared process line formed from the junction of the branch flow paths and configured to provide a shared fluid communication path for process gas from each of the chambers to flow from the clean room to a process line external to the clean room, a plurality of branch pump-down lines, each configured to connect to a corresponding chamber, and a shared pump-down line formed from the junction of the branch pump-down lines and configured to provide a fluid communication path for fluid to flow from the clean room to the pump-down line external to the clean room upon pump-down of at least one of the vacuum chambers.

Description

[Technical field]

[0001] The present invention relates to a vacuum exhaust manifold and method and system for evacuating gases from multiple chambers, such as process chambers used in semiconductor manufacturing. [Background technology]

[0002] Semiconductor manufacturing plants have multiple vacuum chambers located within a clean room to reduce the possibility of contamination. These need to be maintained at a low and stable pressure within each chamber. Traditionally, this has been accomplished with a vacuum pumping system that includes a turbomolecular pump attached to the vacuum chamber with a booster and a backing pump attached to the exhaust of the turbomolecular pump. The backing pump and booster pump can be located outside the clean room in a subfab to reduce contamination and vibration within the clean room.

[0003] The semiconductor process in each chamber is performed asynchronously, periodically, and intermittently, and the type and amount of gas exhausted changes over time. Gases generated by reaction with the process gas (reaction product gases) and residues of the process gas are exhausted to the outside of the chamber by the vacuum exhaust system, and can be supplied to a decontamination device.

[0004] Therefore, the exhaust system for such chambers is required to be able to pump a variety of different gases and to create and maintain a stable high vacuum. A typical set-up for etch systems currently in production is a dedicated backing pump for each process chamber. Summary of the Invention [Problem to be solved by the invention]

[0005] It would be desirable to share a pump among multiple semiconductor process chambers to reduce the overhead associated with multiple pumps while providing a stable high vacuum within each chamber. [Means for solving the problem]

[0006] A first aspect provides a vacuum exhaust system for evacuating a plurality of chambers disposed within a clean room, the vacuum exhaust system comprising: a plurality of branched process gas lines, each configured to connect to a corresponding chamber; a shared process line formed from a junction of the branched lines and configured to provide a shared fluid communication path for process gas from each of the chambers to flow from the clean room to a process line external to the clean room; a plurality of branched pump-down lines, each configured to connect to a corresponding chamber; and a shared pump-down line formed from a junction of the branched pump-down lines and configured to provide a fluid communication path for fluid to flow from the clean room to the pump-down line external to the clean room upon pump-down of at least one of the vacuum chambers.

[0007] In the field of semiconductor processing, such as wafer etching, it is desirable to match vacuum chambers in a vacuum system so that wafers processed in each chamber are substantially identical. To achieve this, each chamber must provide substantially the same vacuum environment at the same stage of the process. Traditionally, this requirement has been addressed by providing the same piping configuration to each chamber, feeding the same pumps. The inventors have recognized that one way to achieve such matching "automatically" is to use shared pumps and shared piping / lines within the tool / cleanroom. Such a configuration would allow for automatic matching of vacuum piping and pumps, and would also result in significant savings in piping and pumps. Although sharing pumps within a system has advantages, it also has potential disadvantages. In particular, the shared piping connecting the vacuum chambers to the remote pumps provides a pathway between the chambers, so that pressure spikes in one chamber can be transmitted to the shared piping and affect the pressure in the other chambers. In semiconductor manufacturing equipment, the pressures in different chambers typically change at different times, as different vacuum chambers perform different processing steps at different times. Additionally, they will be periodically vented and must be pumped back up to high vacuum operation. Thus, if one chamber experiences a pressure spike, perhaps due to venting and subsequent pump-down, this will affect the vacuum in the shared plumbing and, consequently, the vacuum experienced by the other chambers.

[0008] The inventors recognized the advantages of sharing pumps and realized that this drawback could be mitigated by providing separate pumping lines for pumping during pump down and pumping during processing. Thus, pressure spikes from pump down of one chamber are isolated from the process gas shared line and, as a result, do not affect the pressure of the other chamber. Providing additional pump down lines does not result in as much overhead in hardware or space as might be expected, since the pump down lines can have a relatively small cross section since the gases being exhausted are at a relatively high pressure. Furthermore, these lines do not need to be heated since they do not need to carry process gas. Both the pump down line and the process gas line are shared lines, one line exiting the clean room for the process gas, and the other line for the gas exhausted during pump down. It should be noted that the process gas delivered by the process line consists of the process gas supplied to the chamber and the gas products of the reaction in the chamber.

[0009] In some embodiments, the vacuum exhaust system further comprises a plurality of vacuum pumps for evacuating the plurality of chambers, the plurality of vacuum pumps being configured to connect to a corresponding plurality of vacuum chambers, and the plurality of branched process gas flow paths being connected to corresponding exhaust ports of the plurality of vacuum pumps.

[0010] In some embodiments, the vacuum pump comprises a high vacuum pump configured to operate in the molecular flow regime of the gas being pumped.

[0011] The vacuum chamber may have a high vacuum pump, such as a turbomolecular pump, attached to it if a high vacuum is required, such as during an etching process. If the pump is a turbomolecular pump, it is particularly important to maintain a stable pressure in the shared process gas line, since changes in pressure at the turbomolecular pump's exhaust will affect its pumping speed and therefore the vacuum produced.

[0012] In some embodiments, the vacuum exhaust system comprises: a downstream vacuum pump configured to operate in the viscous flow region of the gas and connected to a process line located outside the cleanroom; and a pump-down vacuum pump configured to operate in the viscous flow region of the gas and connected to a pump-down gas path located outside the cleanroom.

[0013] The use of shared process gas lines and shared pump-down gas lines allows a single process vacuum pump and a single pump-down vacuum pump to be located outside the cleanroom. These pumps can be backing pumps for the high vacuum pumps, or pumps for evacuating the chambers if the chambers are used for deposition, for example. In either case, these pumps are often dry pumps and are located outside the cleanroom in a sub-fab to isolate the chambers from the vibrations of these pumps. Since space in a sub-fab is limited, providing a single vacuum pump for multiple vacuum chambers to pump process gases and a single pump for pump-down can be very advantageous as it greatly reduces the space occupied by the pumps in the sub-fab.

[0014] In some embodiments, the multiple branched process gas lines are configured such that the effective conductance of each of the branched lines is substantially the same, and the effective conductance varies between each of the branched lines by less than 20%, preferably less than 10%.

[0015] As mentioned above, it is advantageous for each chamber to be matched, so the vacuum system for each chamber should be substantially the same. If a shared pump is used, this will be the same for each chamber, and for effective chamber matching, it is advantageous if the plumbing is also the same, or if the effective conductances of the branches that are non-shared conduits are substantially the same, or at least vary by less than 20%. That is, the branch with the highest effective conductance has an effective conductance that is less than 20% greater than the branch with the lowest effective conductance.

[0016] In some embodiments, the vacuum pumping system further comprises a control module, the control module comprising a pressure control circuit configured to generate a control signal for controlling the pressure in the shared process line.

[0017] As mentioned above, it is desirable to reduce fluctuations in pressure in the shared process line. Having a separate pump-down line and pump-down pump helps to reduce fluctuations, but the fluctuations can be further reduced by using a pressure control system that generates control signals to control the pressure in the shared process line. Such control can be performed to reduce pressure fluctuations determined by the control circuit from measurements received or predicted from other received signals.

[0018] In some embodiments, the vacuum pumping system further comprises pressure sensors for monitoring pressure in the shared process line, and the pressure control circuit is configured to receive signals from the pressure sensors and generate at least one of the control signals in response to at least one of the received signals to reduce fluctuations in the monitored pressure.

[0019] One way the pressure can be controlled is to have a pressure sensor associated with the shared line and, in response to measurements indicative of changes in pressure, generate a control signal that counters the changes.

[0020] Alternatively and / or additionally, in some embodiments, the pressure control circuit is configured to receive signals indicative of activity in at least one of the chambers, and the pressure control circuit is configured to generate at least one of the control signals in response to at least one of the received signals indicative of the activity.

[0021] The pressure control circuitry can receive signals indicative of activity in the chamber. These signals can be from sensors in the chamber or from control circuitry controlling a process in the chamber. By receiving the signals indicative of activity in the chamber, the control circuitry can generate a pressure control signal that can vary the pressure in the shared line to account for changes in pressure that would result from activity in the chamber.

[0022] In some embodiments, the pressure control circuit is configured to receive a signal indicative of future activity in at least one of the chambers, and the pressure control circuit is configured to generate at least one of the control signals in response to the received signal indicative of the future activity.

[0023] This signal may indicate not only current activity, but also future activity in the chamber, which may be predicted from previous and / or current activity detected, or may be an indication of future activity from the semiconductor control circuitry. If the signal indicates future activity, the control signal may be preempted to generate a signal to modify the pressure in the shared line prior to experiencing the pressure change, further reducing pressure fluctuations.

[0024] In some embodiments, at least one of the control signals generated by the pressure control circuit is a control signal for controlling a pumping speed of at least one of the high vacuum pump or the process downstream vacuum pump.

[0025] One way in which the pressure within a system, and particularly the pressure within a shared pump line, can be controlled is by controlling the speed of one or more pumps in the system.

[0026] In some embodiments, the vacuum pumping system further comprises a purge gas inlet for supplying a controlled flow of purge gas to the shared process line, and at least one of the control signals generated by the pressure control circuit is a control signal for controlling the flow of purge gas.

[0027] Alternatively and / or additionally, the system may comprise a controllable purge gas supply for controlling the amount of purge gas supplied to the shared process line and, consequently, the pressure in the shared process gas line.

[0028] In some embodiments, at least one of the process lines includes at least one variable restrictor.

[0029] Alternatively and / or additionally, in some embodiments, pressure can be controlled using variable restrictors in one or more of the process lines, and at least one of the control signals generated by the pressure control circuit is a control signal for controlling the at least one variable restrictor.

[0030] In some embodiments, the vacuum pumping system comprises a plurality of valves, including a plurality of process valves for isolating or connecting the plurality of chambers to a corresponding plurality of branching process lines, and a plurality of pump-down valves for isolating or connecting the plurality of chambers to a corresponding plurality of branching pump-down lines.

[0031] The vacuum pumping system may include valves for connecting process lines or pump down lines to each vacuum chamber.

[0032] In some embodiments, at least one of the control signals generated by the control module is a control signal for controlling at least one of the plurality of valves.

[0033] The control module can also control the valves that interconnect the pump-down lines and the process gas lines to the different chambers. By having a central control module that controls the pressure in the shared process lines and controls the valves during pump-down, pressure fluctuations that may result from the different connections can be predicted and mitigated.

[0034] In some embodiments, the control module further comprises a pump monitoring circuit for monitoring signals received from sensors associated with the pump, the signals received from the sensors including at least one of an indication of a current supplied to a motor for driving the pump and a signal from a vibration sensor indicative of vibrations generated by the pump.

[0035] The control module may also monitor and control the operation of the pump by receiving signals from sensors associated with the pump. The signals received from the pump indicate the health of the pump and are used to determine when the pump requires service. The control module may control the operation of valves and any back-up pumps to isolate the pump in need of service from the system and potentially replace it with the back-up pump.

[0036] In some embodiments, the system further comprises a process vacuum pump configured to operate in a viscous flow region of the gas and connected to a process line located outside the cleanroom, and an abatement module configured to receive a flow of gas from the process vacuum pump, and the control module configured to send a signal to the abatement module indicative of an amount of abatement gas to supply to the abatement module.

[0037] By having a central control module that receives signals from the processing chambers and / or signals indicative of the pressure in the shared process lines and the purge gas currently being supplied, the control module knows the amount of process gas and reaction product gas currently being exhausted from the vacuum system that requires abatement. Such information can be used by the control module to control the abatement system to supply the required amount of gas to the abatement system, and to adjust the abatement system to the current operating conditions.

[0038] A second aspect provides a vacuum system comprising a plurality of chambers connected to the vacuum pumping system of the first aspect.

[0039] A third aspect provides a method of evacuating multiple vacuum chambers in a clean room, the method comprising the steps of: connecting a process gas exhaust manifold to the multiple vacuum chambers such that multiple process gas branch lines connect the multiple vacuum chambers to a shared process gas line in the clean room; connecting a pump down gas exhaust manifold to the multiple vacuum chambers such that multiple pump down branch lines connect the multiple vacuum chambers to the shared pump down line in the clean room; evacuating the multiple vacuum chambers via the process gas flow path using a vacuum pump located outside the clean room and connected to the shared process gas flow path; monitoring a pressure in the shared process flow path; and generating a control signal to control the pressure in the shared process line to reduce fluctuations in the monitored pressure.

[0040] In some embodiments, the method further includes receiving a signal indicative of activity in at least one of the vacuum chambers and generating at least one control signal in response to at least one of the received signals for controlling pressure in the shared process line to reduce fluctuations in the monitored pressure due to the activity.

[0041] In some embodiments, the method further includes receiving a signal indicative of future activity in at least one of the chambers and generating at least one control signal in response to at least one of the received signals for controlling pressure in the shared process line to reduce fluctuations in the monitored pressure predicted to result from the future activity.

[0042] In some embodiments, the control signal includes a signal for controlling a flow of purge gas to the shared process line, and the method includes controlling the flow of purge gas in response to the control signal.

[0043] Further particular and preferred aspects are set out in the dependent claims. Features of the dependent claims may be combined with features of the independent claims as appropriate, and in other combinations than as explicitly set out in the claims.

[0044] It should be understood that where features of an apparatus are described as operable to provide a certain functionality, this includes features of an apparatus that provide that functionality, or that are adapted or configured to provide that functionality. Embodiments of the present invention will be further described with reference to the accompanying drawings, in which: [Brief description of the drawings]

[0045] [Figure 1] 1 illustrates a vacuum system according to one embodiment. [Diagram 2] 4 illustrates a vacuum system and an abatement system according to a further embodiment. [Diagram 3] FIG. 2 is a flow diagram illustrating steps in a method for evacuating multiple vacuum chambers. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0046] Before describing the embodiments in more detail, an overview will first be presented. The embodiments provide shared pumping of multiple chambers while maintaining a stable vacuum environment through pressure control management of a common foreline manifold, which applies within an etch system. The embodiments also integrate the entire vacuum system, including the chamber pumps, into one common control system. This may be driven from an OEM (original equipment manufacturer) perspective and offers several performance advantages over end-user driven approaches.

[0047] An embodiment provides a design of a vacuum layout for a multi-chamber etch system, including: -Design of symmetrical or near symmetrical process vacuum lines in a multi-chamber system that connect through a process vacuum manifold to a single process vacuum outlet from the etch system. -A single backing pump (with contingency backup) that connects to the vacuum outlet of the etching system and supplies vacuum to the entire system. - A vacuum control module that monitors and controls the pressure management system of the chamber TMP, backing pump, and process vacuum manifold.

[0048] Embodiments provide a vacuum pumping system for multiple vacuum chambers used in semiconductor processing, such as wafer etching or wafer deposition. In such processing systems, it is desirable to provide the same conditions for each wafer so that uniform wafers are produced in each vacuum chamber. Also, in such systems, there are space constraints, especially in sub-fabs below the clean room where backing or dry pumps are typically located. The amount of space available for such pumps is limited. Furthermore, multiple pumps are expensive and can be difficult to provide uniform pumping. Embodiments provide shared pumps between each chamber with a single process gas line exiting from the clean room to the sub-fab.

[0049] An embodiment provides a single pump-down pump with a single pump-down line exiting the cleanroom, and a separate pump can be used from the process gas pump when pumping down the chamber from atmosphere, for example during maintenance, to avoid or at least reduce pressure spikes that can occur from using the process gas piping and pumps during pump-down. In some examples, only one process gas pump is operational at any one time, but there can be two process gas pumps in a sub-fab, one being a backup pump to perform pumping operations, for example when the other pump is under repair.

[0050] The vacuum pumps used in the system may be only in the sub-fab, if the process step is deposition or other process step that does not require high vacuum, in some embodiments there is a high vacuum pump, such as a turbo pump, attached to each chamber, the exhaust of these pumps is connected to a process gas line via branched process gas piping, which in turn each connects to a shared process gas line that exits the clean room and carries the process gas to a pump in the sub-fab. In embodiments, the process gas lines or conduits are symmetrically designed so that each chamber has the same effective conductance or at least a very similar effective conductance. In this regard, the effective conductance provided by the piping from each chamber is designed to be within 20%, preferably within 10%, of each other. That is, the maximum conductance any chamber has is at most 20% greater than the minimum conductance any other chamber has, preferably within 10% of that value.

[0051] Also, embodiments include a central control module configured to control pressure in the shared process gas line to reduce pressure fluctuations in the line to provide more uniform conditions in each chamber. In this regard, embodiments include a pressure control circuit, which may include a pressure sensor, and a controllable purge gas supply for supplying a purge gas to the shared process gas line. The supply of purge gas is increased to compensate for a decrease in gas flow from the chamber, and decreased to compensate for an increase in gas flow from the chamber. In this regard, the pressure control system may detect pressure changes in the shared piping and act reactively to these changes by modifying the flow rate of the purge gas in response to these detected changes. Alternatively and / or additionally, the control circuit may be proactive and predict a change in pressure in the shared piping and adjust the flow of purge gas before such a change is detected. In this regard, the central control module may receive a signal from a system controlling the chamber, where the signal may indicate when a change in process in the chamber will occur, or the circuit may predict an upcoming activity from a signal indicative of a current activity and in response generate an appropriate control signal to compensate for a change in gas flow rate out of the chamber. In this manner, having a central control system can reduce pressure fluctuations in the shared process gas lines.

[0052] In some cases, the central control system can also be used to monitor the health of the pumps, for example, by monitoring the current supplied to the pumps and / or the vibrations generated by the pumps. From these signals, the control circuitry can determine when such pumps require maintenance. The central control module can also be used to control an abatement system downstream of the pumps in the sub-fab. In this regard, the amount of abatement gas required depends on the amount of process gas and reaction product gas exiting the multiple chambers. If the control module has access to signals from the chamber control system, it will have at least some knowledge of the processing steps being performed and will be able to provide a signal to the abatement gas handling system that controls the amount of abatement gas currently required depending on the amount of process gas being exhausted. This can have a significant effect on reducing the amount of abatement gas used in the abatement process.

[0053] Figure 1 shows a vacuum system according to a first embodiment. In this embodiment, the vacuum system has ten chambers 10, each with its own turbomolecular pump 12 connected to the chamber. There are chamber valves in the form of poppet valves, not shown, which can isolate or connect the turbomolecular pump 12 from the chamber. There are branch pipes or lines 14 leading from the exhaust of each turbomolecular pump to a common pipe 16, which takes the process gas from all the chambers and exits the cleanroom via an outlet on the cleanroom floor 45, thereby directing the process gas to a backing pump 20 in the sub-fab. In this embodiment, there is also a back-up backing pump 22.

[0054] In addition to the branch and shared process gas lines 14 and 16, there are also pump-down lines from each chamber for use during pump-down after the chambers have been vented. These are shown as branch pump-down line 30 and shared pump-down line 32. With respect to the process gas lines, they exit the clean room through a single point and connect to a dry pump 40 for pump-down in the sub-fab. Because the pump-down pump 40 is used to pump-down chambers that have been vented to atmosphere, these lines 30, 32 can be significantly smaller than the process gas lines 14, 16, which operate at a higher vacuum. Furthermore, because they do not carry process gas, they do not require heating, which process gas lines may require to avoid material deposition. Thus, while there is some overhead in providing a separate exhaust system for pump-down, this overhead is not as great as if a separate process gas exhaust system were provided, which has the advantage of isolating most of the pressure spikes that occur during pump-down from the shared process line 16.

[0055] Valves are provided in both the pump down lines 30, 32 and the process gas lines 14, 16 to control the evacuation of the different chambers. Downstream of the exhaust of each turbomolecular pump is a valve 18 that allows both the turbomolecular pump 12 and the chamber to be isolated from the process gas vacuum line 14. This can be used when maintenance is required for the chamber and the turbomolecular pump. Also, in each branch 30 of the pump down line, the pump down line has a valve 38 that isolates the chamber from the pump down line when the pump chamber is not being pumped down. In some embodiments, there is also a line between the pump down branch 30 and the process gas branch 14, this connecting line can have its own valve 37. This valve allows the chamber and the turbomolecular pump to be pumped down together, where the turbomolecular pump is vented in case of maintenance being required. In this regard, there is also a chamber valve between the chamber and the turbomolecular pump that is used when venting the chamber. Venting the chamber is more commonly performed than venting the turbomolecular pump.

[0056] In this embodiment, there is a vacuum control module 50 that is used to provide central control of the vacuum system. The vacuum control module 50 provides pressure control to maintain a uniform pressure in the shared process gas line 16 and reduce any pressure fluctuations.

[0057] To provide pressure control, the control module 50 can control a purge gas supply 54 that allows a controllable flow of purge gas into the shared line 16. The control module 50 can also be configured to control pumps and valves in the various systems. In some cases, there can be controllable restrictions in at least some of the piping to control the conductance of the piping, which can also be controlled by the central control module 50.

[0058] In some embodiments, the control module 50 receives signals from the chamber to provide visibility of activity in the chamber. These signals can come from sensors associated with the chamber or from control circuitry for controlling the process in the chamber. In some embodiments, the central control module 50 can include control circuitry for controlling the vacuum pumping system in addition to control circuitry for controlling the process in the chamber. The central control module 50 can also be configured to control the dry pumps 20, 40 in the sub-fab.

[0059] In some embodiments, the vacuum control module 50 controls the pressure in the shared line 16 by monitoring the pressure therein using a pressure sensor 52. In response to a detected change in the monitored pressure, the control module 50 sends a control signal to the purge gas supply 54 to vary the amount of purge gas supplied to the shared line to compensate for any detected pressure changes. Alternatively and / or additionally, the vacuum control module 50 can play a more preventative predictive role, identifying the various processes being performed from signals received from the chamber, predicting changes in gas flow rates therefrom, and controlling the purge gas supply 54 in advance of or in sync with these predicted changes. The control module 50 also controls the valves and pumps itself in response to signals received, such that the speed of the pumps can be varied depending on the process step being performed, and valves can be opened or closed if maintenance or venting of the chamber is required.

[0060] In some embodiments, the vacuum control module 50 may also receive signals from sensors associated with the pump that provide indications of the health of the pump, such as the current used to drive the turbomolecular pump 12 or vibrations the pump generates within the sub-fab. For example, if there is a large change in the current required to drive the turbomolecular pump, this indicates that the pump requires maintenance. Similarly, vibration sensors associated with the dry pumps 40, 20 may indicate that they require maintenance. If the dry pump 20 has a backup pump 22, a valve (not shown) may be used to isolate the pump 20 from the system and use the backup pump as the system's pump.

[0061] FIG. 2 shows an alternative embodiment similar to that of FIG. 1, but additionally including an abatement system 60, 62 attached to the process pump for abatement of process gases and reaction product gases exiting the vacuum system. This abatement system 60 can also be controlled by the vacuum control module 50, and the amount of abatement gas sent to the abatement system can vary depending on the amount and type of gas currently exiting the vacuum system. This can be determined by the central control module receiving signals indicative of the current and / or future activity of the chamber. In this way, a more efficient and environmentally friendly abatement system is provided. The abatement system 60 can have a backup abatement system 62 for use, for example, while the system 60 is being maintained.

[0062] 3 is a flow diagram showing steps S10-S110 of a method for evacuating multiple vacuum chambers according to an embodiment. In step S10, a process gas exhaust manifold with multiple branch lines leading to a shared line is connected to the corresponding multiple vacuum chambers. In step S20, a pump-down exhaust manifold with multiple branch lines leading to the shared line is connected to the corresponding multiple vacuum chambers. Then, in step S30, at least some of the chambers are evacuated through the process gas line, and the exhausted gases leave the clean room through the shared process gas line and pass through a shared pump operating in the viscous flow region located in the sub-fab. In some embodiments, each chamber has a turbomolecular pump between the process branch line and the vacuum chamber.

[0063] In step S40, a controlled amount of purge gas is supplied to the shared process gas line to maintain a substantially constant pressure therein. In step S50, a pressure sensor is used to monitor the pressure in the shared process line, and if a change is detected in step S60, the amount of purge gas supplied is altered in step S70 to offset the detected change. If no change is detected, or step S70 is followed by step S80, which determines whether a signal has been received indicating a change in activity in one or more chambers. Such a change in activity may mean that the amount and / or type of gas exhausted from the chambers is changing, and thus, if so determined in step S90, a control signal is generated in step S100 to alter the amount of purge gas to offset the change in gas flow from the chambers and maintain a substantially steady pressure in the shared process gas line.

[0064] In addition, such signals can be used to control the abatement system in step S110; for example, if a signal is sent in step S90 to change the amount and possibly the type of gas exhausted by the chamber, the amount of abatement gas required will also change, and these signals can therefore be used to control the abatement system in step S110, and in particular, the amount of gas used in the abatement system, thereby making the abatement system more efficient.

[0065] In summary, the embodiments provide vacuum chambers where each chamber is matched and wafers in different chambers experience substantially the same vacuum environment. In the embodiments, symmetrical plumbing, i.e., plumbing with the same effective conductance, is fully integrated. By providing shared process lines and shared pumps, matching occurs somewhat automatically, and by providing a pressure control system and separate backup lines, pressure fluctuations that may occur with different processes in different chambers are mitigated.

[0066] By using a central control system to control the vacuum system, the treatment system and the exhaust gas treatment system, the abatement system can be adjusted to the current conditions rather than having to be adjusted to maximum all the time, which means a more efficient system.

[0067] The central control module can receive signals from the chambers, allowing it to predict, rather than simply detect, changes in gas flow so that it can respond in advance of pressure changes occurring in the shared lines, allowing for more efficient pressure control and reduced pressure fluctuations.

[0068] In some embodiments, there is also a communication and control link between the abatement system and the vacuum control module that allows the emission management control system to be integrated into a general process control system.

[0069] Although exemplary embodiments of the present invention are disclosed in detail herein with reference to the accompanying drawings, it should be understood that the present invention is not limited to the detailed embodiments, and various changes and modifications may be made by those skilled in the art without departing from the scope of the present invention as defined by the claims and their equivalents. [Explanation of symbols]

[0070] 10 Vacuum chamber 12 Turbomolecular pump 14 Process gas branch line 16 Shared process gas lines 18,37,38 Valve 20 Dry Pump 22 Backup dry pump 30 Branch pump down line 32 Shared pump-down line 40 Pump Down Pump 45 Clean Room Floor 50 Control Module 52 Purge gas supply unit 54 Pressure Sensor 60 Abatement Module 62 Backup abatement module

Claims

1. 1. A vacuum pumping system for evacuating a plurality of chambers arranged in a clean room, comprising: a plurality of branched process gas lines, each configured to connect to a corresponding chamber; a shared process line formed from the junction of the branching process gas lines and configured to provide a shared fluid communication path for process gas from each of the chambers to flow from the clean room to a process line external to the clean room; a plurality of branched pump-down lines, each configured to connect to a corresponding chamber; a shared pump-down line formed from a junction of the branch pump-down lines and configured to provide a fluid communication path for fluid to flow from the cleanroom to a pump-down line external to the cleanroom upon pump-down of at least one of the chambers. The vacuum pumping system further comprises a control module, the control module comprising a pressure control circuit configured to generate a control signal to control pressure in the shared process line; the pressure control circuit is configured to receive a signal indicative of future activity in at least one of the chambers, the pressure control circuit being configured to generate at least one of the control signals in response to the received signal indicative of the future activity. A vacuum pumping system comprising:

2. the vacuum exhaust system further comprising a plurality of vacuum pumps for evacuating the plurality of chambers, the plurality of vacuum pumps being configured to connect to the corresponding plurality of vacuum chambers, and the plurality of branched process gas lines being connected to corresponding exhaust ports of the plurality of vacuum pumps.

2. The vacuum pumping system of claim 1.

3. the plurality of vacuum pumps being comprised of a plurality of high vacuum pumps configured to operate in a molecular flow region of the gas being pumped; 3. The vacuum pumping system of claim 2.

4. The vacuum pumping system includes: a downstream vacuum pump configured to operate in a viscous flow region of the gas being pumped and connected to the process line located outside the cleanroom; a pump-down vacuum pump configured to operate in a viscous flow region of the gas and connected to the pump-down line located outside the cleanroom; Equipped with 4. A vacuum pumping system according to claim 1.

5. the plurality of branched process gas lines are configured such that an effective conductance of each of the branched process gas lines is substantially the same, the effective conductance varying by less than 20% between each of the branched process gas lines; 5. A vacuum pumping system according to claim 1.

6. the vacuum pumping system further comprising a pressure sensor for monitoring pressure in the shared process line; the pressure control circuit is configured to receive signals from the pressure sensors and generate at least one of the control signals in response to at least one of the received signals to reduce fluctuations in the monitored pressure.

6. A vacuum pumping system according to claim 1.

7. the pressure control circuit is configured to receive signals indicative of an activity in at least one of the chambers, the pressure control circuit being configured to generate at least one of the control signals in response to at least one of the received signals indicative of the activity.

7. A vacuum pumping system according to claim 1.

8. The vacuum pumping system includes: a plurality of vacuum pumps for evacuating the plurality of chambers, the plurality of vacuum pumps being configured to connect to the corresponding plurality of vacuum chambers, the plurality of branched process gas lines being connected to corresponding exhaust ports of the plurality of vacuum pumps; a process downstream vacuum pump configured to operate in a viscous flow region of the gas being pumped, said process downstream vacuum pump being connected to the process line located outside of the cleanroom; and At least one of the control signals generated by the pressure control circuit is a control signal for controlling a pumping speed of at least one of the vacuum pumps.

8. A vacuum pumping system according to claim 1.

9. the vacuum pumping system further comprising a purge gas inlet for supplying a controlled flow of purge gas to the shared process line; At least one of the control signals generated by the pressure control circuit is a control signal for controlling the flow of the purge gas.

9. A vacuum pumping system according to any one of claims 1 to 8.

10. The vacuum pumping system includes a plurality of valves, the plurality of valves including: a plurality of process valves for isolating or connecting the plurality of chambers to a corresponding plurality of branch process lines; a plurality of pump-down valves for isolating or connecting the plurality of chambers to the corresponding plurality of branch pump-down lines; 10. A vacuum pumping system according to claim 1.

11. At least one of the control signals generated by the pressure control circuit is a control signal for controlling at least one of the plurality of valves.

11. A vacuum pumping system according to claim 10 when dependent on any one of claims 1 to 10.

12. the control module further comprising a pump monitoring circuit for monitoring signals received from sensors associated with the vacuum pump, the signals received from the sensors including at least one of an indication of a current supplied to a motor for driving the vacuum pump and a signal from a vibration sensor indicative of vibrations generated by the vacuum pump.

9. A vacuum pumping system according to claim 2, 3 or 8.

13. the vacuum pumping system further comprises a process vacuum pump configured to operate in a viscous flow region of the gas being pumped and connected to the process line located outside the cleanroom; and an abatement module configured to receive a flow of gas from the process vacuum pump, the control module configured to send a signal to the abatement module indicative of an amount of abatement gas to be supplied to the abatement module.

13. A vacuum pumping system according to any one of claims 1 to 12.

14. A vacuum system comprising a plurality of chambers connected to a vacuum pumping system according to any one of claims 1 to 13.

15. 1. A method for evacuating a plurality of vacuum chambers in a clean room, comprising: connecting a process gas exhaust manifold to the plurality of vacuum chambers such that a plurality of process gas branch lines connect the plurality of vacuum chambers to a shared process gas line within the clean room; connecting a pump-down gas exhaust manifold to the plurality of vacuum chambers such that a plurality of pump-down branch lines connect the plurality of vacuum chambers to a common pump-down line within the clean room; evacuating the plurality of vacuum chambers through the shared process gas line using a vacuum pump located outside the clean room and connected to the shared process gas line; monitoring the pressure of the shared process gas line; generating a control signal to control pressure in the shared process gas line to reduce fluctuations in the monitored pressure; receiving a signal indicative of future activity in at least one of the vacuum chambers; generating at least one control signal in response to at least one of the received signals for controlling pressure in the shared process gas line to reduce fluctuations in the monitored pressure predicted to occur due to the future activity. A method comprising:

16. The method comprises: receiving a signal indicative of activity in at least one of the vacuum chambers; generating at least one control signal in response to at least one of the received signals for controlling pressure in the shared process gas line to reduce fluctuations in the monitored pressure due to the activity. The method of claim 15.

17. the control signal comprises a signal for controlling a flow of purge gas to the shared process gas line, the method comprising controlling the flow of the purge gas in response to the control signal.

17. The method according to claim 15 or 16.

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