Vacuum pumping system and method
By using a multi-pump sharing system, the vacuum pump can be switched between the load-locked chamber and the transfer chamber using control circuits and valve systems, which solves the problem of the limited evacuation speed of the load-locked chamber and improves wafer processing capabilities.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- EDWARDS LTD
- Filing Date
- 2024-07-16
- Publication Date
- 2026-04-14
AI Technical Summary
In existing wafer transfer systems, the evacuation speed of the load-locked chamber limits wafer processing capacity. While increasing the size and capacity of the vacuum pump can solve this problem, it is costly.
A multi-pump sharing system is adopted, which periodically connects a larger vacuum pump to a smaller vacuum chamber through a control circuit system and a valve system to provide additional pumping capacity while maintaining a constant pressure in the larger vacuum chamber.
The increased evacuation speed of the load-locking chamber enhances wafer handling capacity without increasing the cost of a vacuum pump, resulting in more efficient wafer transfer.
Smart Images
Figure CN121866409A_ABST
Abstract
Description
Technical Field
[0001] The field of this invention relates to vacuum evacuation systems, particularly those used for evacuating systems used for transferring wafers to and from processing chambers. Background Technology
[0002] Wafer processing or transfer systems provide a means of introducing and removing wafers from a semiconductor processing chamber without excessively affecting the vacuum within the processing chamber or introducing contaminants into the system. These transfer systems typically include smaller load-locked chambers configured to circulate between atmospheric pressure and a low pressure. These chambers are used to transfer wafers from atmospheric pressure to a wafer transfer chamber maintained at or near the pressure within the semiconductor processing chamber. It may be desirable to increase the number of wafers that a wafer transfer system can process in a given time, and the limiting factor for this number may be the rate at which the load-locked chambers can be evacuated to the desired pressure. This can be addressed by increasing the size and capacity of the vacuum pumps used to evacuate these chambers; however, such solutions incur cost overhead. Summary of the Invention
[0003] A first aspect provides a vacuum pumping system for evacuating a vacuum system, the vacuum system comprising a plurality of vacuum chambers, the plurality of vacuum chambers including: at least one smaller vacuum chamber operable to circulate between a predetermined pressure below atmospheric pressure and atmospheric pressure; and a larger vacuum chamber; the vacuum pumping system comprising: a first vacuum pump; a second vacuum pump; a valve system configured to selectively connect and isolate the first and second vacuum pumps from the plurality of vacuum chambers; and a control circuit system configured to: in response to determining that the pressure in one of the at least one smaller vacuum chambers will drop to the predetermined pressure within a first time period, control the valve system such that the first and second pumps are isolated from the larger vacuum chamber and fluidly connected to the smaller vacuum chamber, thereby causing both the first and second pumps to evacuate the smaller vacuum chamber to the predetermined pressure; and when the smaller vacuum chamber is at the predetermined pressure, control the valve system such that the second vacuum pump is isolated from the smaller vacuum chamber and fluidly connected to the larger vacuum chamber, thereby causing the second vacuum pump to pump air from the larger vacuum chamber.
[0004] Vacuum systems (such as wafer transfer stations) have different pumping load requirements at different times. These systems have: a larger vacuum chamber configured to maintain a substantially constant low pressure; and smaller vacuum chambers that cycle between atmospheric pressure and lower pressures. It is recognized that for a pumping system with multiple vacuum pumps, different load requirements can be effectively met by providing some sharing of the vacuum pumps, and such sharing allows the system to provide increased pumping speed to the smaller vacuum chambers when needed, while still maintaining a substantially constant lower pressure in the larger vacuum chamber. In practice, the pump used to maintain the vacuum in the larger vacuum chamber can be periodically switched to assist in evacuating the smaller vacuum chambers(s), thereby providing increased pumping capacity when needed, while still maintaining the required vacuum in the larger vacuum chamber.
[0005] The evacuation system includes a first vacuum pump and a second vacuum pump, valves, and a control circuit system that controls the valves such that both pumps are connected to the smaller vacuum chamber during at least a portion of the time it is being evacuated from atmospheric pressure to a lower pressure, and the second vacuum pump is connected to the larger vacuum chamber once the smaller vacuum chamber has reached the lower pressure. In practice, the second vacuum pump, typically used to maintain the larger vacuum chamber at its lower pressure, is used to help provide increased evacuation capacity during or at least a portion of the time the smaller vacuum chamber is to be evacuated. This increases the speed of evacuation of the smaller vacuum chamber and has a limited effect on the larger vacuum chamber. In this way, increased evacuation capacity is provided without the need for additional or larger pumps.
[0006] A smaller vacuum chamber is a vacuum chamber smaller than a larger vacuum chamber. It can be slightly smaller, or it can be more than ten times smaller. For example, a larger vacuum chamber can be about 300 liters, while a smaller vacuum chamber can be about 20 liters.
[0007] In some embodiments, the control circuitry is configured to: in response to determining that the smaller vacuum chamber has reached the predetermined pressure, control the valve system to isolate the second vacuum pump from the smaller vacuum chamber and connect the second vacuum pump to the larger vacuum chamber.
[0008] Although additional pumping capacity can be provided for only a portion of the time the smaller vacuum chamber is being evacuated, in some embodiments it is provided for the entire time period, with the second vacuum pump connected to the smaller vacuum chamber in response to detecting the start of the evacuation process and disconnected from it in response to detecting that the desired pressure has been reached.
[0009] In some embodiments, the vacuum system isolates the first vacuum pump from the smaller vacuum chamber when the smaller vacuum chamber is to be restored to atmospheric pressure.
[0010] The control circuitry of the vacuum system controls the valves between the chamber and the pump to connect the pump to the desired chamber during a evacuation cycle. These valves may be part of the vacuum system and may be located near and associated with the chamber. The control circuitry of the evacuation system controls the valve system of the evacuation system so that a second vacuum pump can assist the first vacuum pump in evacuating a smaller vacuum chamber and isolate the second vacuum pump from the larger vacuum chamber during that period.
[0011] In some embodiments, the vacuum system is configured to periodically connect the larger vacuum chamber to the at least one smaller vacuum chamber when the at least one smaller vacuum chamber is at the predetermined pressure.
[0012] In some embodiments, the vacuum system further includes a second smaller vacuum chamber operable to circulate between a second predetermined pressure and atmospheric pressure during a second time period, the second time period not overlapping with the first time period. The vacuum system includes a valve such that the first vacuum pump is in fluid communication with the smaller vacuum chamber during the cycle in which the smaller vacuum chamber is being evacuated to the first predetermined pressure, and is in fluid communication with the second smaller vacuum chamber during the cycle in which the second smaller vacuum chamber is being evacuated to the second predetermined pressure.
[0013] The system being evacuated may include a single smaller vacuum chamber, or multiple smaller chambers may exist. These chambers may circulate between the same or different predetermined pressures within the same or different time periods, and the time periods during which the chambers are evacuated may not overlap, thus allowing a single pump to evacuate each of them at different times.
[0014] In some embodiments, the vacuum system is configured to control valves within the vacuum system such that the first vacuum pump is isolated from the second smaller vacuum chamber during the period when the smaller vacuum chamber is being evacuated to the first predetermined pressure and is also isolated from the smaller vacuum chamber during the period when the second smaller vacuum chamber is being evacuated to the second predetermined pressure.
[0015] If the evacuation cycles of the smaller vacuum chambers do not overlap in time, a first vacuum pump can be used to evacuate each of these chambers at different times. This can be controlled by valves in the vacuum system.
[0016] In some embodiments, when the durations of the first time period and the second time period are substantially the same, the control system is configured to: in response to determining that the pressure in the second smaller vacuum chamber will drop to the second predetermined pressure during the second time period, control the valve system such that the first pump and the second pump are isolated from the larger vacuum chamber and fluidly connected to the second smaller vacuum chamber, thereby causing both the first vacuum pump and the second vacuum pump to evacuate the second smaller vacuum chamber to the second predetermined pressure; and when the second smaller vacuum chamber is at the second predetermined pressure, control the valve system such that the second vacuum pump is isolated from the second smaller vacuum chamber and fluidly connected to the larger vacuum chamber, thereby causing the second vacuum pump to evacuate the larger vacuum chamber.
[0017] When both smaller chambers have the same evacuation time limit, it is possible to use two vacuum pumps to facilitate evacuation for at least a portion of the evacuation cycle in both smaller chambers, and this can be achieved through controllable valves.
[0018] In some embodiments, the duration of the second time period is more than 35% longer than the duration of the first time period, and the control system is configured to: in response to determining that the pressure in the second smaller vacuum chamber will decrease, control the valve system such that the first vacuum pump is in fluid communication with the second smaller vacuum chamber and the second vacuum pump is isolated from the second smaller vacuum chamber and in fluid communication with the larger vacuum chamber.
[0019] If the second smaller vacuum chamber can be evacuated more slowly than the first smaller vacuum chamber, it is possible that it does not require additional pumping capacity, and the second vacuum pump can remain connected to the larger vacuum chamber while the second smaller vacuum chamber is being evacuated.
[0020] In some embodiments, the first predetermined pressure and the second predetermined pressure comprise substantially the same pressure, while in other embodiments they may be slightly different pressures.
[0021] The predetermined pressure reached by evacuating one or more smaller vacuum chambers and the pressure maintained by the larger vacuum chamber can be within 30% of each other. Similar pressures within the chambers mean that when the smaller and larger chambers are coupled together, for example, to move a wafer between them, there is no excessive pressure difference, and only a limited amount of gas is transferred between these chambers. Limiting the airflow helps prevent particles from being agitated and moving between the chambers. In some embodiments, it may be advantageous for the smaller vacuum chamber to be at a lower pressure than the larger vacuum chamber when the smaller and larger vacuum chambers are coupled together, such that any disturbed particles are drawn away from the larger vacuum chamber and into the smaller vacuum chamber, which may be configured to be coupled to a processing chamber. However, in other embodiments, the larger vacuum chamber may be maintained at a lower pressure than the pressure reached by evacuating(s) the smaller vacuum chambers(s). In some cases, periodically reaching the reduced pressure in the smaller vacuum chamber is a time-critical step, and therefore, a very low pressure is not required to reduce the time required for this step. It should be noted that in embodiments where the smaller vacuum chambers are significantly smaller than the larger vacuum chamber, any pressure difference between the two chambers when they are connected together should have a limited effect on the pressure in the larger vacuum chamber.
[0022] In some embodiments, the control circuitry includes a signal input for receiving a signal from the vacuum system, the control circuitry being configured to determine, in response to a control signal received from the vacuum system, that the smaller vacuum chamber will be evacuated from atmospheric pressure.
[0023] In some embodiments, the control circuitry includes a signal input for receiving a signal from the vacuum system, the control circuitry being configured to determine, in response to a control signal received from the vacuum system, that the smaller vacuum chamber has reached the predetermined pressure.
[0024] In some cases, the control circuitry can receive signals from the vacuum system and, in response to these signals, control the valve system to engage or isolate the pump. In other embodiments, the control circuitry can detect changes in the vacuum system by detecting changes in the pumping system (such as pressure changes within or to the pump, or changes in the current used by the pump motor) and can use these changes to trigger valve changes. The latter does not require a signal from the vacuum system but has the disadvantage of a delay between the change and its detection, resulting in potentially slower cycle times and a slightly reduced capacity of the pumped vacuum system.
[0025] In some embodiments, the valve system includes one of a three-way valve or two two-way valves, the valve system being configured to isolate or connect the second vacuum pump to the larger vacuum chamber and to isolate or connect the second vacuum pump to a vacuum line pumped by the first vacuum pump.
[0026] In some embodiments, after the vacuum system is shut down and before the pressure cycle of the at least one smaller vacuum chamber, the control circuitry is configured to control the valve system such that the first and second vacuum pumps are in fluid communication with the larger vacuum chamber and that the first and second vacuum pumps facilitate the evacuation of the larger vacuum chamber from atmospheric pressure to an operating vacuum.
[0027] In addition to increasing the speed at which smaller vacuum chambers (multiple) can be evacuated to a predetermined pressure, two pumps can be connected to the larger vacuum chamber if evacuation may be required after vacuum system maintenance. This allows for faster evacuation of the larger vacuum chamber.
[0028] In some embodiments, the larger vacuum chamber includes a wafer transfer chamber within a semiconductor processing system, and the at least one smaller vacuum chamber includes a load-locking chamber for receiving a wafer into or removing a wafer from the transfer chamber.
[0029] Semiconductor processing systems require the acceptance of wafers into various processing chambers and the use of transfer chambers to facilitate wafer loading and unloading, as well as wafer movement between different processing chambers. Transfer chambers are relatively large and need to be maintained at a relatively constant pressure, and are used to protect the processing chambers from pressure variations and contaminants. Load-lock chambers are used to feed wafers into and remove wafers from the transfer chambers, and are potential sources of contamination and pressure variations. To improve the processing capacity of such systems, it may be desirable to reduce the time required for periodically evacuating the load-lock chamber. A evacuation system according to embodiments for evacuating such wafer transfer systems allows for increased wafer processing capacity without unduly increasing system costs.
[0030] In some embodiments, the vacuum system includes two smaller vacuum chambers, one of which includes a wafer inlet chamber, and the second smaller vacuum chamber includes a wafer removal chamber.
[0031] In some embodiments, the first vacuum pump and the second vacuum pump have different pumping capacities. In some embodiments, the pumping capacity of the first vacuum pump is at least 1.5 times and up to twice that of the second vacuum pump.
[0032] In some embodiments, the first vacuum pump has a depth of between 150 m 3 / h and 250 m 3 The second vacuum pump has a pumping capacity between 80 m / h, while the third vacuum pump has a pumping capacity between 80 m / h. 3 / h and 150 m 3 Their pumping capacity is between 230 m / h. Therefore, when connected together, they provide a pumping capacity between 230 m / h.3 / h and 400 m 3 Pumping capacity is between / h. In this respect, pumping capacity is the capacity at full speed and is specific to the specific pump selected for a specific system and will be a value within that range.
[0033] In other embodiments, the first and second vacuum pumps have the same pumping capacity, thus enabling the use of two identical, smaller vacuum pumps. They may, for example, each have a pumping capacity of 200 m³ / s. 3 The pumping capacity is 400 m³ / h, which is provided when the two are connected together. 3 / h is sufficient to rapidly evacuate a small vacuum chamber.
[0034] A second aspect provides a method for evacuating a vacuum system, the vacuum system comprising a plurality of vacuum chambers, the plurality of vacuum chambers including: at least one smaller vacuum chamber operable to circulate between a predetermined pressure below atmospheric pressure and atmospheric pressure; and a larger vacuum chamber; the method comprising: determining that a pressure within one of the at least one smaller vacuum chambers will drop to the predetermined pressure within a first time period; controlling a valve system such that a first vacuum pump and a second vacuum pump are isolated from the larger vacuum chamber and fluidly connected to the smaller vacuum chamber; evacuating the smaller vacuum chamber to the predetermined pressure using both the first vacuum pump and the second vacuum pump; determining that the smaller vacuum chamber has reached the predetermined pressure; and controlling the valve system such that a second vacuum pump is isolated from the smaller vacuum chamber and fluidly connected to the larger vacuum chamber, thereby causing the second vacuum pump to evacuate the larger vacuum chamber.
[0035] In some embodiments, the determining step includes receiving a signal indicating the condition from the vacuum system.
[0036] In other embodiments, the determining step includes detecting changes in the condition of the pumping system, such as pressure changes or changes in current consumed by the motor.
[0037] Further specific and preferred aspects are set forth in the appended independent and dependent claims. Features of the dependent claims may be combined with features of the independent claims where appropriate, and may be combined in combinations other than those expressly stated in the claims.
[0038] When a device feature is described as operable to provide a function, it will be understood that this includes device features that provide that function or are adapted or constructed to provide that function. Attached Figure Description
[0039] Embodiments of the invention will now be further described with reference to the accompanying drawings, in which: Figure 1A vacuum pumping system according to the prior art is shown; Figure 2 A vacuum pumping system according to an embodiment is shown; and Figure 3 A flowchart illustrating the steps in a method according to an embodiment is shown. Detailed Implementation
[0040] Before discussing the embodiments in any further detail, an overview will first be provided.
[0041] In semiconductor processing systems, wafer transfer stations may exist for inserting and removing wafers into processing chambers. To maintain a vacuum within the processing chambers, these transfer stations typically include wafer transfer chambers that are kept at a low pressure and intermittently communicated with one or more processing chambers. Load-locked chambers also exist, which have a small volume and circulate relatively rapidly between atmospheric and low pressures. To evacuate these chambers to the desired vacuum within a short timeframe, vacuum pumps with relatively high evacuation rates or capacities may be required. Vacuum pumps, typically with lower capacities, are also provided for maintaining larger transfer chambers at the required reduced pressure.
[0042] To reduce the pump size required to provide the desired pressure cycle rate for the load lock chamber, a vacuum system with control circuitry and valves is provided. This system allows the vacuum pump used to maintain the vacuum in the larger wafer transfer chamber to be periodically positioned in fluid communication with the load lock chamber, enabling it to assist in evacuating that chamber. In this way, the desired pumping rate can be achieved using a combination of vacuum pumps that allows for a smaller vacuum pump typically used for evacuating the load lock chamber while still achieving the desired evacuation rate.
[0043] In the example layout, for example, if 350 m is required... 3 A design scheme that uses a pumping speed of / hr to achieve a specific pump down time in a load-locked chamber would require a pump with a power consumption greater than 1 kW under extreme conditions. For example, at a pumping speed of 100 m... 3 At / hr, the pump size required to maintain the transfer chamber at the desired vacuum can be significantly smaller. An embodiment proposes providing a higher required evacuation capacity by using two pumps with a valve system, allowing switching between evacuation of the transfer chamber and evacuation of the load-locked chamber during evacuation cycles using the smaller pump. This operation can be initiated by a signal from the tool, but an alternative solution could be a control circuit system that detects this condition. In this way, relative to a required capacity of 350 m³ / hr, the required pump size can be significantly reduced. 3 A pump with a capacity of / hr and a capacity of 100 m 3A pump with a capacity of, for example, 250 m³ / hr. 3 A pump with a capacity of / hr is acceptable as a larger vacuum pump because, when coupled to a smaller pump, it will provide the desired total capacity. In some embodiments, two pumps with the same capacity may be used, provided that the combined capacity provides the desired pumping rate for evacuating the smaller vacuum chamber. In this example, a pump with a capacity of 200 m³ / hr may be used. 3 Two pumps per hr.
[0044] In some embodiments, where the evacuation and decompression times of the load-locked chambers differ (one or a pair of chambers (possibly the wafer inlet chamber) requires rapid evacuation and decompression, and one or a pair of chambers (e.g., the wafer outlet chamber) allows for slower evacuation and decompression), the switching function of the wafer transfer chamber pump only needs to be used for rapid evacuation and decompression, and a dedicated vacuum pump for the load-locked chamber can be used separately when the slower evacuation and decompression is acceptable to the customer.
[0045] In some embodiments, triggering of the switching valve can be accomplished by detecting a large current in a pump that evacuates the load lock chamber.
[0046] The switching function can be achieved through a 3-way valve or a combination of two 2-way valves.
[0047] Figure 1 A wafer transfer station 5 according to the prior art is shown. The wafer transfer station 5 includes two pairs of load-locking chambers 30, one pair configured to receive a pair of wafers from a cleanroom wafer processing system 2 at atmospheric pressure via a robot 4 at atmospheric pressure and transfer them to a transfer chamber 40 at reduced pressure using a low-pressure robot 4; the other pair is configured to receive wafers from the transfer chamber 40 at reduced pressure and again deliver them to the wafer processing system 2 at atmospheric pressure using a robot 4. The load-locking chambers 30 can be arranged in pairs and receive wafers in parallel.
[0048] The load-locking chamber 30 is evacuated by a larger vacuum pump 10 and circulates between atmospheric pressure and a lower pressure at or near the pressure in the transfer chamber 40. The load-locking chamber 30 is connected to the wafer processing system or the transfer chamber via an open or closed slit valve. The robot 4 performs wafer transfer in each direction.
[0049] When the inlet load-locking chamber 30 is at atmospheric pressure, the vacuum system or tool opens the slit valve connecting to the outside and receives the wafer from the wafer processing system 2. Then, the tool control system closes the slit valve and opens valve V1. A larger vacuum pump 10 then evacuates chamber 30 to a predetermined pressure, and when this pressure is reached, the tool control system opens the slit valve between the load-locking inlet chamber 30 and the transfer chamber 40, and the wafer is moved into the transfer chamber 40. Then, valve V1 is closed, and the inlet load-locking chamber 30 is vented to the atmosphere.
[0050] Once the wafer has been processed by the processing chambers 50, it is returned to the wafer processing system via the lower outlet load lock chamber 30. The vacuum system or tool control valve V2 opens, causing the larger vacuum pump 10 to evacuate the outlet load lock chamber 30. When a wafer is ready to be delivered and the pressure has reached a predetermined level, the slit valve between the load lock chamber 30 and the transfer chamber 40 opens, and the wafer is received in the outlet load lock chamber 30. At this point, V2 closes, the load lock chamber is vented, the inlet slit valve opens, and the wafer is removed.
[0051] The transfer chamber 40 should be kept at a substantially constant low pressure throughout the process and evacuated by a smaller vacuum pump 20 connected to the transfer chamber 40 via valve V5.
[0052] In cases where the wafer transfer chamber needs increased capacity and can handle more wafers, a limiting factor might be the rate at which these load-locked chambers can be evacuated while cycling between atmospheric and low pressure. To increase this cycling rate, a larger vacuum pump 10 could be used, but this would incur a cost overhead. Alternatively, [the following can be done]... Figure 2 The system shown in the embodiment increases the evacuation capacity used to evacuate the load lock chamber 30.
[0053] Figure 2 An air extraction system according to an embodiment is shown, the air extraction system being connected to... Figure 1 The wafer transfer system shown is similar to the wafer transfer system in the diagram. The wafer transfer system is similar to... Figure 1A similar configuration is used to allow the load-locked chamber 30 to circulate between atmospheric pressure and a low pressure, while the transfer chamber 40 remains at a substantially constant low pressure. In this embodiment, valve systems V3 and V4 are provided to provide increased evacuation capacity to the load-locked chamber 30 and accelerate its evacuation, thereby enabling the wafer transfer station to process more wafers in a given time. These valve systems are controlled by control circuitry 25 and are configured to connect vacuum pump 20 to the load-locked chamber during evacuation, such that both vacuum pump 20 and vacuum pump 10 contribute to the evacuation of that chamber. Then, when no pump is needed to assist in evacuating the load-locked chamber 30, the valve systems and control circuitry connect vacuum pump 20 to the transfer chamber 40. In this way, vacuum pump 20 increases the rate at which the smaller load-locked vacuum chamber 30 is evacuated while still providing sufficient evacuation power to maintain a vacuum in the larger transfer chamber 40. In some cases, both the inlet and outlet load-locked vacuum chambers 30 are required to be evacuated at the same time, and both use two pumps for the evacuation process. In other embodiments, one of the load lock chambers (possibly the inlet load lock chamber) has a faster evacuation time requirement than the outlet load lock chamber, and in this case, the control circuit system can control valves V3 and V4 to connect two pumps only to the inlet load lock chamber during evacuation, while the other outlet load lock chamber is evacuated by a single pump.
[0054] In this way, by using a control circuit system and two additional valves instead of requiring an increase in the size of the vacuum pump 10, faster evacuation of the lock-up vacuum chamber for smaller loads and increased wafer processing station capacity can be achieved.
[0055] Figure 3 A flowchart illustrating the steps of a method according to an embodiment is shown. This method can be... Figure 2 The device performs the operation. In the initial step S10, it is determined that the pressure within at least one of the smaller vacuum chambers will drop to a predetermined pressure within a first time period. This can be determined in response to a signal received from the vacuum system (processing tool), or it can be determined by the monitoring circuit system detecting a pressure change or a load change on the pump. In response to this detection, the control circuit system 25 controls... Figure 2 The valve system V3 and V4 isolates both the first and second vacuum pumps from the larger vacuum chamber 40 and allows them to be in fluid communication with the smaller vacuum chamber 30. In practice, valve V3 is closed and valve V4 is open, and thus the two pumps cooperate to evacuate the smaller vacuum chamber 30.
[0056] At step S30, the smaller vacuum chamber is evacuated to a predetermined pressure by both the first vacuum pump 10 and the second vacuum pump 20. At step S40, it is determined that the smaller vacuum chamber has reached the predetermined pressure. This may be done in response to a circuit system associated with the sensing and control circuitry system 25, or it may be done in response to a signal received from the vacuum system. When this is determined, the control valve systems V3 and V4 isolate the second vacuum pump from the smaller vacuum chamber 30 and fluidly communicate it with the larger vacuum chamber 40, evacuating it. Figure 2 In one embodiment, valve V4 is closed and valve V3 is opened.
[0057] Although illustrative embodiments of the invention have been disclosed in detail herein with reference to the accompanying drawings, it should be understood that the invention is not limited to the precise embodiments, and that various changes and modifications can be made therein by those skilled in the art without departing from the scope of the invention as defined by the appended claims and their equivalents.
[0058] Figure Labels 2. Wafer Processing System 4 robots 5 Wafer Transfer Stations 10 First Vacuum Pump 20 Second vacuum pump 25 Control Circuit System 30 Smaller vacuum chamber, load-locking chamber 40 Larger vacuum chambers, wafer transfer vacuum chambers 50 Processing Room V1, V2, V5 Vacuum System Valves V3 and V4 are vacuum system valves.
Claims
1. A vacuum pumping system for evacuating a vacuum system, the vacuum system comprising a plurality of vacuum chambers, the plurality of vacuum chambers comprising: At least one smaller vacuum chamber, operable to circulate between a predetermined pressure below atmospheric pressure and atmospheric pressure; And a larger vacuum chamber; The vacuum pumping system includes: First vacuum pump; Second vacuum pump; A valve system configured to selectively connect and isolate the first vacuum pump and the second vacuum pump from the plurality of vacuum chambers; and The control circuit system is constructed as follows: In response to determining that the pressure within one of the at least one smaller vacuum chambers will drop to the predetermined pressure within a first time period, the valve system is controlled such that the first and second pumps are isolated from the larger vacuum chamber and fluidly communicated with the smaller vacuum chamber, thereby causing both the first and second vacuum pumps to evacuate the smaller vacuum chamber to the predetermined pressure; and When the smaller vacuum chamber is at the predetermined pressure, the valve system is controlled to isolate the second vacuum pump from the smaller vacuum chamber and to fluidly communicate the second vacuum pump with the larger vacuum chamber, thereby causing the second vacuum pump to evacuate the larger vacuum chamber.
2. The vacuum pumping system according to claim 1, wherein, The control circuit system is configured to: in response to determining that the smaller vacuum chamber has reached the predetermined pressure, control the valve system to isolate the second vacuum pump from the smaller vacuum chamber and connect the second vacuum pump to the larger vacuum chamber.
3. The vacuum pumping system according to claim 1 or 2, wherein, The vacuum system further includes a second, smaller vacuum chamber operable to cycle between a second predetermined pressure and atmospheric pressure during a second time period, the second time period not overlapping with the first time period, wherein, when the durations of the first and second time periods are substantially the same, the control system is configured to control the valve system such that: In response to determining that the pressure in the second smaller vacuum chamber will decrease, the valve system is controlled such that the first and second pumps are isolated from the larger vacuum chamber and fluidly communicated with the second smaller vacuum chamber; and When the second smaller vacuum chamber is at the second predetermined pressure, the valve system is controlled to isolate the second vacuum pump from the second smaller vacuum chamber and to fluidly communicate the second vacuum pump with the larger vacuum chamber, thereby causing the second vacuum pump to pump air from the larger vacuum chamber.
4. The vacuum pumping system according to any of the preceding claims, wherein, The vacuum system further includes a second, smaller vacuum chamber operable to cycle between a second predetermined pressure and atmospheric pressure during a second time period, the second time period not overlapping with the first time period, wherein the control system is configured such that, when the duration of the second time period is more than 35% longer than the duration of the first time period: In response to determining that the pressure in the second smaller vacuum chamber will decrease, the valve system is controlled such that the first vacuum pump is in fluid communication with the second smaller vacuum chamber and the second vacuum pump is isolated from the second smaller vacuum chamber and in fluid communication with the larger vacuum chamber.
5. The vacuum pumping system according to claim 3 or 4, wherein the vacuum system causes the first vacuum pump to be in fluid communication with the smaller vacuum chamber during the cycle in which the smaller vacuum chamber is being evacuated to a first predetermined pressure, and to be in fluid communication with the second smaller vacuum chamber during the cycle in which the second smaller vacuum chamber is being evacuated to the second predetermined pressure.
6. The vacuum pumping system of claim 5, wherein the vacuum system isolates the first vacuum pump from the second smaller vacuum chamber during the period when the smaller vacuum chamber is being evacuated to the first predetermined pressure and from the smaller vacuum chamber during the period when the second smaller vacuum chamber is being evacuated to the second predetermined pressure.
7. The vacuum pumping system according to any one of claims 3 to 6, wherein, The first predetermined pressure and the second predetermined pressure comprise substantially the same pressure.
8. The vacuum pumping system according to any of the preceding claims, wherein, The control circuitry includes a signal input for receiving signals from the vacuum system, and the control circuitry is configured to determine, in response to a control signal received from the vacuum system, that a smaller vacuum chamber will be evacuated from atmospheric pressure.
9. The vacuum pumping system according to any one of claims 1 to 7, wherein, The control circuitry is configured to determine, in response to detecting a change in the evacuation system, that the at least one smaller vacuum chamber will be evacuated from atmospheric pressure, the change including a pressure change or a change in the current supplied to the motor of the first vacuum pump.
10. The vacuum pumping system according to any of the preceding claims, wherein the valve system includes one of a three-way valve or two two-way valves, the valve system being configured to isolate or connect the second vacuum pump to the larger vacuum chamber and to isolate or connect the second vacuum pump to a vacuum line pumped by the first vacuum pump.
11. The vacuum pumping system according to any of the preceding claims, wherein, After the vacuum system is shut down and before the pressure cycle of the at least one smaller vacuum chamber, the control circuitry is configured to control the valve system such that the first and second vacuum pumps are in fluid communication with the larger vacuum chamber and that the first and second vacuum pumps facilitate the evacuation of the larger vacuum chamber from atmospheric pressure to an operating vacuum.
12. The vacuum pumping system according to any of the preceding claims, wherein, The vacuum pumping system is used to pump air from the wafer processing system, and the larger vacuum chamber includes a wafer transfer chamber and the at least one smaller vacuum chamber includes a load locking chamber.
13. A method for evacuating a vacuum system, the vacuum system comprising a plurality of vacuum chambers, the plurality of vacuum chambers comprising: At least one smaller vacuum chamber, operable to circulate between a predetermined pressure below atmospheric pressure and atmospheric pressure; And a larger vacuum chamber; The method includes: It is determined that the pressure in one of the at least one smaller vacuum chambers will drop to the predetermined pressure within a first time period; The control valve system isolates the first and second vacuum pumps from the larger vacuum chamber and allows them to be in fluid communication with the smaller vacuum chamber; The smaller vacuum chamber is evacuated to the predetermined pressure using both the first vacuum pump and the second vacuum pump; It was determined that the smaller vacuum chamber had reached the predetermined pressure; and The valve system is controlled to isolate the second vacuum pump from the smaller vacuum chamber and to allow it to be in fluid communication with the larger vacuum chamber, thereby enabling the second vacuum pump to pump air from the larger vacuum chamber.
14. The method according to claim 13, wherein, The determining step includes detecting a change in at least one of pressure or current supplied to the pump motor in the air extraction system.
15. The method according to claim 13 or claim 14, wherein, The determination step includes receiving a signal indicating the status from the vacuum system.