Cold machine system

Abstract

The present invention provides a cooling machine system with low cost, space saving, and high withstand voltage performance. The cooling machine system (1) includes an internal circulation path (C1), an external circulation path (C2), and a control device (40). A refrigerant tank (17), an internal circulation pump (11), and a refrigerator (12) are provided in the internal circulation path (C1). The external circulation path (C2) has a supply path (20) and a return path (25), and an external circulation pump (21) and a temperature sensor (23) are provided in the supply path (20). A throttling mechanism (28) is provided in a communication path that communicates between the return path (25) and the refrigerant tank (17). An opening / closing control valve (16) is provided in the internal circulation path (C1). One end of a pressurization path (30) is connected to a position upstream of the opening / closing control valve (16) in the internal circulation path (C1), and the other end of the pressurization path (30) is connected to a position upstream of the throttling mechanism (28) in the communication path. The control device (40) controls the operation of the opening / closing control valve (16) based on the measurement result of the temperature sensor (23).

Description

Technical Field

[0001] The present invention relates to a chiller system, and more particularly to a chiller system that circulates a refrigerant between a wafer mounting stage in an inspection apparatus for electrically inspecting a plurality of chips formed on a wafer. Background Art

[0002] In the semiconductor manufacturing process, an electrical property inspection of chips formed on a wafer is performed using a detector. In order to shorten the inspection time and reduce costs, in recent years, the number of chips inspected simultaneously has been increasing. For example, even in the case of chips with relatively low heat generation such as DRAM (Dynamic Random Access Memory) and flash memory, if the number of chips inspected simultaneously increases, the heat generated from the entire wafer during inspection also increases.

[0003] In addition, chips such as in-vehicle use chips are used in a wide range of applications. In order to ensure that the chips operate normally in a temperature environment corresponding to the application, the range of the temperature environment during inspection has also expanded. Therefore, in a wide temperature environment, the heat generation of the chips during inspection increases.

[0004] Consequently, various techniques for controlling the temperature of the surface of the mounting stage on which the wafer is mounted in the detector have been proposed in the past. For example, in Patent Document 1, a chiller mechanism for controlling the temperature of the wafer chuck (mounting stage) of the detector is disclosed. This chiller mechanism has a cooling path and a coolant cooling path.

[0005] In the cooling path, a tank for holding the coolant is connected to the wafer chuck through a path from the tank to the wafer chuck and a path for returning from the wafer chuck to the tank. By circulating the coolant between the tank and the wafer chuck using a pump provided in the cooling path, the wafer chuck is cooled.

[0006] In the coolant cooling path, the tank is connected to the cooler through a path from the tank to the cooler and a path for returning from the cooler to the tank. The coolant cooled by the cooler returns to the tank by a pump provided in the coolant cooling path. And by adjusting the amount of the circulating coolant using a flow rate adjusting valve provided in the coolant cooling path, the temperature of the coolant held in the tank is adjusted.

[0007] Prior Art Documents

[0008] Patent Documents

[0009] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2008-311492 Summary of the Invention

[0010] Problems to be Solved by the Invention

[0011] In addition, in the case of applying a cooling mechanism such as the technology described in Patent Document 1 to a detector that undergoes electrical inspection at high temperatures, conventionally, a fluorine-based inert liquid with a high boiling point has been used as the coolant.

[0012] This is because when the temperature of the coolant exceeds the boiling point, there may be problems such as abnormal temperature control due to the occurrence of cavitation of the coolant, and damage to the impeller of the circulation pump due to cavitation.

[0013] However, coolants with high boiling points tend to have an increase in kinematic viscosity due to an increase in viscosity at low temperatures. Therefore, there are problems as follows: in the low-temperature region, the flow rate of the coolant decreases due to the increase in kinematic viscosity, and the cooling effect on the wafer mounting stage is reduced compared to coolants with low boiling points. In addition, there is also a problem that, due to the increase in kinematic viscosity, an increase in the necessary shaft power of the circulation pump also occurs and the power consumption increases.

[0014] For these reasons, a system that can use a coolant with a low boiling point to ensure performance in the low-temperature region and can transport the coolant without boiling the coolant even in the high-temperature region is desired. As a method for increasing the boiling point of a coolant with a low boiling point, there is a method described in Patent Document 1 of applying pressure to the path of the cooling mechanism using compressed air or the like to increase the boiling point of the coolant.

[0015] However, in a structure such as the cooling mechanism described in Patent Document 1, it is difficult to locally pressurize only the path from the wafer mounting stage to the suction part of the circulation pump that is particularly desired to be pressurized. Therefore, it is necessary to pressurize the entire path of the cooling mechanism using a tank or the like.

[0016] In this case, it is necessary to improve the pressure resistance performance of the related equipment of the liquid contact part including auxiliary equipment. Since the equipment is composed of stronger components, the degree of freedom in equipment selection is restricted or the equipment becomes larger compared to the past. As a result, there is a problem of an increase in device cost. In addition, along with the enlargement of the equipment, there is also a problem that the cooling mechanism itself on which these equipment are mounted also increases in floor area compared to the past.

[0017] The present invention has been completed in view of such circumstances, and an object thereof is to provide a cooling machine system with low cost, space saving, and high pressure resistance performance.

[0018] Means for Solving the Problems

[0019] To solve the above problems, the following inventions are provided.

[0020] The chiller system of the first solution circulates the refrigerant between the wafer mounting stage and the chiller unit. Among them, the chiller system includes: an internal circulation path that enables the refrigerant to circulate inside the chiller unit; an external circulation path that enables the refrigerant to circulate between the chiller unit and the wafer mounting stage; and a control device that controls the chiller unit. A refrigerant tank, an internal circulation pump, and a refrigerator are provided in the internal circulation path. The external circulation path has a supply path leading from the chiller unit to the wafer mounting stage and a return path leading from the wafer mounting stage back to the chiller unit. An external circulation pump and a temperature sensor are provided in the supply path. The return path has a communication path that connects the return path and the refrigerant tank. A throttling mechanism that restricts the flow rate of the refrigerant flowing into the refrigerant tank is provided in the communication path. In the internal circulation path, an opening and closing control valve is provided at a position upstream of the refrigerant tank. The chiller system has a pressurization path for pressurizing the refrigerant flowing in the return path. One end of the pressurization path is connected to a position upstream of the opening and closing control valve in the internal circulation path, and the other end of the pressurization path is connected to a position upstream of the throttling mechanism in the communication path. The control device controls the operation of the opening and closing control valve based on the temperature set value or the measurement result of the temperature sensor.

[0021] Based on the first solution, in the chiller system of the second solution, when the temperature set value or the temperature measured by the temperature sensor is equal to or higher than the boiling point of the refrigerant, or equal to or higher than the temperature obtained by subtracting a specified margin from the boiling point, the control device closes the opening and closing control valve.

[0022] Based on the second solution, in the chiller system of the third solution, when the temperature set value or the temperature measured by the temperature sensor is lower than the boiling point of the refrigerant, or lower than the temperature obtained by subtracting a specified margin from the boiling point, the control device opens the opening and closing control valve.

[0023] Based on the second or third solution, in the chiller system of the fourth solution, a pressure sensor is provided in the return path. When the temperature set value or the temperature measured by the temperature sensor is equal to or higher than the boiling point of the refrigerant (or the temperature obtained by subtracting a specified margin from the boiling point), the control device performs pressurization control of the return path based on the pressure measured by the pressure sensor.

[0024] Based on the fourth solution, in the chiller system of the fifth solution, the control device controls the operation of the internal circulation pump based on the pressure measured by the pressure sensor as pressurization control.

[0025] Based on the fourth or fifth solution, in the chiller system of the sixth solution, the throttling mechanism is composed of an electrically driven valve capable of adjusting the opening degree of the communication path. The control device controls the opening degree of the electrically driven valve based on the pressure measured by the pressure sensor as pressurization control.

[0026] Based on any one of the first to sixth embodiments, the chiller system of the seventh embodiment has a connection path disposed between the internal circulation path and the external circulation path and sending the refrigerant flowing in the internal circulation path to the external circulation path. A three-way valve is provided at the connection position where the internal circulation path is connected to the connection path, and the control device controls the operation of the three-way valve based on the measurement result of the temperature sensor.

[0027] Based on the seventh embodiment, in the chiller system of the eighth embodiment, when the temperature measured by the temperature sensor is higher than a specified value, the control device opens the connection path by using the three-way valve.

[0028] Based on the eighth embodiment, in the chiller system of the ninth embodiment, when the temperature measured by the temperature sensor is lower than a specified value, the control device closes the connection path by using the three-way valve.

[0029] Based on any one of the first to ninth embodiments, the chiller system of the tenth embodiment is provided with a heater in the supply path, and the control device controls the heating of the refrigerant by the heater based on the temperature measured by the temperature sensor.

[0030] Advantages of the Invention

[0031] According to the present invention, a chiller system with low cost, space saving, and high pressure resistance can be realized. Description of the Drawings

[0032] Figure 1 is a schematic structural diagram of the chiller system of the present embodiment.

[0033] Figure 2 is a functional block diagram of the control device.

[0034] Figure 3 is a flowchart showing the control method of the chiller system. Detailed Embodiments

[0035] Hereinafter, the chiller system of the embodiment of the present invention will be described with reference to the drawings.

[0036] In Figure 1 shows the schematic structure of the chiller system of the present embodiment. As Figure 1 shown, the chiller system 1 of the present embodiment includes a chiller unit 10 that circulates the refrigerant for cooling the wafer mounting stage 24 and a control device 40 that controls the entire chiller system 1.

[0037] Any liquid can be used as the refrigerant, but when the kinematic viscosity is high, the shaft power required for the circulation pump also increases. Therefore, the refrigerant is preferably a liquid with a relatively low viscosity at low temperatures. More specifically, the refrigerant is, for example, a fluorine-based inert liquid. More specifically, as the fluorine-based inert liquid, for example, Novec 7200 (boiling point at atmospheric pressure: 76 °C) manufactured by 3M Company and Galden 135 (boiling point at atmospheric pressure: 135 °C) manufactured by Solvay Company can be cited.

[0038] Refrigerants with relatively low viscosities at low temperatures tend to have low boiling points. Here, a low boiling point means, for example, a boiling point in the range of about 70 °C to about 140 °C. On the contrary, a high boiling point means, for example, a boiling point higher than about 150 °C. The cooling machine system 1 can be appropriately applied to detectors that take advantage of refrigerants with relatively low viscosities at low temperatures and are inspected at high temperatures.

[0039] In the cooling machine system 1, the refrigerant path is generally divided into an internal circulation path C1 and an external circulation path C2. In Figure 1 , the internal circulation path C1 is shown by black arrows, and the external circulation path C2 is shown by white arrows. In addition, the direction of the arrow indicates the direction of the refrigerant flow. In the following description, the base end side of the arrow is set as the upstream side of the refrigerant flow, and the front end side of the arrow is set as the downstream side of the refrigerant flow for explanation.

[0040] The internal circulation path C1 enables the refrigerant to circulate between the refrigerant tank 17 and the refrigerator 12 inside the cooling machine unit 10. The external circulation path C2 enables the refrigerant to circulate between the cooling machine unit 10 and the wafer mounting stage 24. In the case of a detector used for inspection at a relatively high temperature, sometimes the temperature of the refrigerant in the external circulation path C2 becomes a high temperature close to the boiling point of the refrigerant.

[0041] Hereinafter, the structure of the internal circulation path C1 will be described in detail. A refrigerant tank 17, an internal circulation pump 11, and a refrigerator 12 are provided in the internal circulation path C1. The refrigerant tank 17 stores the refrigerant. The internal circulation pump 11 sends the refrigerant supplied from the refrigerant tank 17 to the refrigerator 12. The refrigerator 12 cools the refrigerant to a specified temperature.

[0042] A three-way valve 14 is provided downstream of the refrigerator 12, and the refrigerator 12 and the three-way valve 14 are fluidly connected through a path 13. The three-way valve 14 and the refrigerant tank 17 are fluidly connected through a path 15, and an opening and closing control valve 16 is provided at a position upstream of the refrigerant tank 17 on the path 15. The opening and closing control valve 16 is composed of an electrically driven valve such as a solenoid valve or an electric valve. And, the three-way valve 14 and the suction port of the external circulation pump 21 in the external circulation path C2 are fluidly connected through a connection path 19. That is, the connection path 19 fluidly connects between the internal circulation path C1 and the external circulation path C2.

[0043] In other words, the three-way valve 14 is provided at the connection position where the path 13 starting from the chiller 12, the path 15 for returning the refrigerant to the refrigerant tank 17, and the connection path 19 in the internal circulation path C1 are connected. By operating (controlling) the three-way valve 14, it is possible to switch between a state where the path 13 and the connection path 19 are fluidly connected and the path 15 is closed and a state where the path 13 and the path 15 are fluidly connected and the connection path 19 is closed. The control of the three-way valve 14 will be described in detail later.

[0044] Next, the structure of the external circulation path C2 will be described in detail. The external circulation path C2 is roughly divided into a supply path 20 and a return path 25. The supply path 20 is a path for supplying the refrigerant from the chiller unit 10 to the wafer mounting stage 24. The return path 25 is a path for returning the refrigerant from the wafer mounting stage 24 to the chiller unit 10.

[0045] In the supply path 20, an external circulation pump 21, a heater 22, and a temperature sensor 23 are provided in sequence from the upstream side (chiller unit 10 side) toward the wafer mounting stage 24. The external circulation pump 21 sends out the refrigerant to the wafer mounting stage 24. The heater 22 heats the refrigerant flowing in the supply path 20. The temperature sensor 23 measures the temperature of the refrigerant flowing in the supply path 20.

[0046] The wafer mounting stage 24 has a built-in refrigerant flow path (not shown). The refrigerant flow path is fluidly connected to the supply path 20 and the return path 25. By flowing the refrigerant adjusted to an appropriate temperature in the refrigerant flow path, the temperature of the surface of the wafer mounting stage 24 is controlled to a temperature suitable for inspection by a detector (inspection device). The structure of the wafer mounting stage 24 having the refrigerant flow path is well-known, and thus the detailed description thereof is omitted. The refrigerant that has passed through the refrigerant flow path of the wafer mounting stage 24 returns to the chiller unit 10 via the return path 25.

[0047] The return path 25 branches into a first branch path 29 and a second branch path 27 at a branch point 31 within the chiller unit 10. The first branch path 29 is fluidly connected to the supply path 20 downstream of the three-way valve 14 and upstream of the external circulation pump 21. A pressure sensor 26 for measuring the pressure of the refrigerant in the return path 25 (specifically, in the first branch path 29) is provided on the first branch path 29.

[0048] The second branch path 27 is connected to the refrigerant tank 17, and a throttling mechanism 28 is provided at a position on the upstream side of the refrigerant tank 17 in the second branch path 27. The throttling mechanism 28 is composed of a throttle hole (throttle portion) that narrows the flow path cross-section in the second branch path 27, and the flow rate of the refrigerant flowing in the second branch path 27 is restricted by this throttle hole. It should be noted that the throttling mechanism 28 may also be composed of an electrically driven valve such as a solenoid valve or an electric valve as in the modification example described later. The second branch path 27 corresponds to the "communication path" of the present invention. It should be noted that in the present invention, the "communication path" is not limited to the second branch path 27, but is used in a broad concept that also includes the first branch path 29 that communicates with the refrigerant tank 17 via the second branch path 27 and the return path 25 that is the branch source of the first branch path 29 and the second branch path 27.

[0049] Moreover, a pressurizing path 30 is provided between the internal circulation path C1 and the external circulation path C2 for pressurizing the return path 25. One end (internal circulation path C1 side) of the pressurizing path 30 is located on the path 15 of the internal circulation path C1, more specifically, between the three-way valve 14 and the opening / closing control valve 16 (that is, at a position upstream of the opening / closing control valve 16). The other end (external circulation path C2 side) of the pressurizing path 30 is located on the second branch path 27, more specifically, between the throttling mechanism 28 and the branch point 31 (that is, at a position upstream of the throttling mechanism 28). It should be noted that the other end of the pressurizing path 30 is not limited to the second branch path 27, and may be, for example, on the first branch path 29.

[0050] In addition, a filter 18 is provided in the refrigerant tank 17. Depending on the characteristics of the refrigerant, sometimes if it becomes above the boiling point, the refrigerant in the external circulation path C2 may generate harmful substances such as acid due to thermal decomposition. Therefore, the cold machine system 1 of the present embodiment is provided with a filter 18 that adsorbs harmful substances generated in the refrigerant. This filter 18 is preferably provided at a position where it is difficult to be exposed to high temperatures. Specifically, for example, the filter 18 is provided inside the refrigerant tank 17 (refer to Figure 1 ). However, this example is not intended to limit the position of the filter 18.

[0051] In the chiller system 1, when using a refrigerant with a low boiling point, it is necessary to suppress cavitation of the refrigerant. In the present embodiment, the control device 40 described later controls each part (three-way valve 14, heater 22, on-off control valve 16, internal circulation pump 11) of the chiller system 1 based on the measurement results of the temperature sensor 23 and the pressure sensor 26, so that the return path 25 in the external circulation path C2 can be locally pressurized through the pressurization path 30, the cavitation of the refrigerant can be suppressed, and the chiller system 1 can operate well. Thus, it is possible to avoid an increase in cost required to improve the pressure resistance performance and the enlargement of the device, and a system that can use a refrigerant with a low boiling point to ensure performance in a low temperature region and transport the refrigerant without boiling the refrigerant even in a high temperature region can be realized.

[0052] Next, Figure 2 the functional structure of the control device 40 will be described. As Figure 2 shown, the control device 40 includes a main control unit 43, a temperature control unit 41, and a pressure control unit 42. The main control unit 43 comprehensively controls each part of the chiller system 1.

[0053] The temperature control unit 41 controls the switching of the three-way valve 14 and the heating of the heater 22 so that the refrigerant in the supply path 20 of the external circulation path C2 has a temperature within a specified range based on the temperature of the refrigerant in the supply path 20 of the external circulation path C2 measured by the temperature sensor 23.

[0054] The pressure control unit 42 controls the opening and closing of the on-off control valve 16 based on the temperature of the refrigerant in the supply path 20 of the external circulation path C2 measured by the temperature sensor 23. Further, the pressure control unit 42 controls the operation (rotation speed) of the internal circulation pump 11 based on the pressure in the return path 25 (first branch path 29) of the external circulation path C2 measured by the pressure sensor 26. Thus, the pressure control unit 42 controls the pressure in the return path 25 of the external circulation path C2 so as to suppress cavitation of the refrigerant.

[0055] Each part (main control unit 43, temperature control unit 41, and pressure control unit 42) constituting the control device 40 is implemented by, for example, a personal computer, a workstation, a PLC (Programmable Logic Controller), etc. The control device 40 includes a CPU (Central Processing Unit) that controls the operations of the devices constituting the chiller system 1, a ROM (Read Only Memory), a storage device (e.g., HDD (Hard Disk Drive) or SSD (Solid State Drive), etc.) that stores control programs, and a SDRAM (Synchronous Dynamic Random Access Memory) that can be used as the working area of the CPU.

[0056] Moreover, the control device 40 receives an operation input by the operator via an operation unit (not shown), and sends a control signal corresponding to the operation input to each part constituting the chiller system 1 to control the operations of the devices. The operation unit includes, for example, a keyboard, a mouse, or a touch panel, etc.

[0057] Next, Figure 3 A control method for the chiller system 1 will be described. First, the control device 40 measures the temperature of the refrigerant flowing in the supply path 20 using the temperature sensor 23 (step S1.0). Here, the temperature measured by the temperature sensor 23 shows a temperature substantially equal to the temperature of the refrigerant supplied to the wafer mounting stage 24. Next, the temperature control unit 41 of the control device 40 determines whether the temperature of the refrigerant measured in step S10 is greater than a specified value (step S12).

[0058] When the temperature of the refrigerant is greater than the specified value (step S12: YES), the temperature control unit 41 drives the three-way valve 14 to connect the path 13 on the chiller 12 side to the connection path 19 and closes the path 15 on the refrigerant tank 17 side (step S14). That is, the temperature control unit 41 opens the connection path 19 through the three-way valve 14. After that, the process proceeds to step S22.

[0059] In the internal circulation path C1, the refrigerant cooled by the chiller 12 and maintained at a constant low temperature circulates. When the temperature of the refrigerant measured in step S10 is greater than the specified value (set value), it is necessary to lower the temperature of the refrigerant flowing in the external circulation path C2. The temperature control unit 41 uses the three-way valve 14 to connect the path 13 on the chiller 12 side to the connection path 19 and closes the path 15 on the refrigerant tank 17 side. As a result, the low-temperature refrigerant flowing in the internal circulation path C1 mixes with the high-temperature refrigerant flowing in the external circulation path C2, lowering the temperature of the refrigerant flowing in the external circulation path C2.

[0060] The mixing ratio of the low-temperature refrigerant flowing in the internal circulation path C1 and the high-temperature refrigerant flowing in the external circulation path C2 of the three-way valve 14 is appropriately set by the temperature control unit 41 according to the temperature of the refrigerant measured in step S10.

[0061] On the other hand, when the temperature of the refrigerant measured in step S10 is equal to or lower than a specified value (step S12: No), there is no need to lower the temperature of the refrigerant. Therefore, the temperature control unit 41 uses the three-way valve 14 to connect the path 13 on the chiller 12 side and the path 15 on the refrigerant tank 17 side, and closes the connection path 19 (step S16). As a result, the low-temperature refrigerant flowing in the internal circulation path C1 does not flow into the external circulation path C2 via the connection path 19. During the operation of the chiller system 1, the temperature of the refrigerant measured by the temperature sensor 23 is fed back to the temperature control unit 41, and based on this temperature, the temperature control unit 41 continuously controls the three-way valve 14.

[0062] After step S16, the temperature control unit 41 determines whether the temperature of the refrigerant measured in step S10 is within a specified range, so as to determine whether the refrigerant should be heated (step S18). When the temperature of the refrigerant is not within the specified temperature range (step S18: Yes), the temperature of the refrigerant in the external circulation path C2 is too low, so the refrigerant needs to be heated. Then, the temperature control unit 41 uses the heater 22 to heat the refrigerant (step S20), and proceeds to step S22. On the other hand, when the temperature of the refrigerant is within the specified temperature range (step S18: No), there is no need to heat the refrigerant in the external circulation path C2, so the process of step S20 (heating of the refrigerant by the heater 22) is not performed, and the process proceeds to step S22.

[0063] Next, in step S22, the pressure control unit 42 of the control device 40 determines whether the temperature of the refrigerant or the set temperature of the refrigerant is equal to or higher than the boiling point of the refrigerant in the environment of the external circulation path C2. The temperature of the refrigerant used in this determination is preferably the temperature of the refrigerant measured by the temperature sensor 23 immediately before step S22. It should be noted that the temperature of the refrigerant measured in step S10 can also be used. When the temperature of the refrigerant or the set temperature of the refrigerant is equal to or higher than the boiling point of the refrigerant (step S22: Yes), the pressure control unit 42 closes the on-off control valve 16 (step S24). As a result, the refrigerant flowing in the internal circulation path C1 flows into the second branch path 27 side via the pressurization path 30, and the flow rate of the refrigerant toward the refrigerant tank 17 is restricted by the throttling mechanism 28, so the pressure in the return path 25 of the external circulation path C2 rises.

[0064] Here, when the opening / closing control valve 16 is closed (step S24), the second branch path 27 is narrowed by the throttling mechanism 28. Therefore, the pressure required to press the refrigerant from the internal circulation path C1 side to the path from the wafer mounting stage 24 to the suction port of the external circulation pump 21 (i.e., the return path 25) also increases.

[0065] Then, the pressure control unit 42 increases the driving speed of the internal circulation pump 11 based on the pressure measured by the pressure sensor 26 provided in the first branch path 29, thereby increasing the pressing pressure of the internal circulation pump 11 via the pressurizing path 30 (step S26). It should be noted that the internal circulation pump 11 is preferably composed of an inverter-driven pump.

[0066] By narrowing a part of the path (the second branch path 27) of the refrigerant toward the refrigerant tank 17 using the throttling mechanism 28 and increasing the pressing pressure of the internal circulation pump 11, the pressure in the return path 25 of the external circulation path C2 can be increased to be above the vapor pressure of the refrigerant. Thereby, cavitation of the refrigerant can be suppressed and the refrigerant can circulate well in the external circulation path C2.

[0067] It should be noted that the path from the outlet of the refrigerant flow path in the wafer mounting stage 24 to the suction port of the external circulation pump 21 (i.e., the return path 25) is subject to the above-described pressure control because the pressure is likely to decrease, but the supply path 20 is in a pressurized state from the beginning due to the ejection pressure of the external circulation pump 21. Therefore, no mechanism for preventing pressure reduction is particularly provided for the supply path 20.

[0068] On the other hand, when the temperature of the refrigerant or the set temperature of the refrigerant is less than the boiling point of the refrigerant (step S22: No), the control device 40 opens the opening / closing control valve 16 (step S28). As a result, the refrigerant flowing in the internal circulation path C1 can flow into the refrigerant tank 17 through the path 15 provided with the opening / closing control valve 16. Therefore, the pressurization using the pressing pressure of the internal circulation pump 11 is not performed within the range of the path from the wafer mounting stage 24 to the suction port of the external circulation pump 21 (i.e., within the return path 25 of the external circulation path C2). And since the pressurization using the pressing pressure of the internal circulation pump 11 is not performed, the pressure difference between the inlet and the outlet of the refrigerant flow path in the wafer mounting stage 24 is obtained more greatly. Thus, the cooling effect on the wafer mounting stage 24 due to the increase in the flow rate of the refrigerant flowing in the refrigerant flow path in the wafer mounting stage 24 is obtained more greatly.

[0069] The control device 40 repeatedly performs the processes of step S10 to step S28 during the operation of the chiller system 1 (step S30). Thereby, cavitation of the refrigerant can be suppressed and the chiller system 1 can be operated well.

[0070] In the present embodiment, it has been described that the pressure control unit 42 determines whether to open or close the opening / closing control valve 16 based on whether the temperature of the refrigerant or the set temperature of the refrigerant is equal to or higher than the boiling point of the refrigerant. However, in order to reliably prevent cavitation in the external circulation pump 21, it is necessary to pressurize to a pressure equal to or higher than the saturated vapor pressure of the refrigerant, and it is also necessary to consider the pressure reduction in the suction portion of the external circulation pump 21. Therefore, it is also possible to determine the opening and closing of the opening / closing control valve 16 based on whether the temperature of the refrigerant or the set temperature of the refrigerant is equal to or higher than a value obtained by subtracting a specified margin considering these pressure fluctuations from the boiling point of the refrigerant.

[0071] [Effect]

[0072] As described above, according to the chiller system 1 of the present embodiment, based on the measurement result of the temperature sensor 23 provided in the external circulation path C2, the operation of the opening / closing control valve 16 provided in the internal circulation path C1 is controlled, so that a part (return path 25) of the external circulation path C2 can be locally pressurized by the pressurization path 30, cavitation of the refrigerant can be suppressed, and the chiller system 1 can be operated well. As a result, it is possible to avoid the cost required to improve the pressure resistance performance and the enlargement of the device, and it is possible to realize a system that can use a refrigerant with a low boiling point to ensure performance in a low temperature region and can transport the refrigerant without boiling the refrigerant even in a high temperature region. As a result, it is possible to realize a chiller system with low cost, space saving, and high pressure resistance performance.

[0073] Specifically, when the set temperature of the refrigerant or the temperature measured by the temperature sensor 23 is equal to or higher than the boiling point of the refrigerant, the opening / closing control valve 16 is closed, so that the path from the wafer mounting stage 24 to the suction port of the external circulation pump 21 (that is, within the return path 25 of the external circulation path C2) is pressurized by the pressure of the internal circulation pump 11 using the pressurization path 30. In addition, based on the measurement result of the pressure sensor 26 provided in the external circulation path C2, the driving speed of the internal circulation pump 11 is increased, so that the pressure of the internal circulation pump 11 rises. As a result, the pressure within the return path 25 of the external circulation path C2 can be increased to suppress cavitation of the refrigerant.

[0074] On the other hand, when the set temperature of the refrigerant or the temperature measured by the temperature sensor 23 is lower than the boiling point of the refrigerant, the opening / closing control valve 16 is opened, so that the refrigerant flowing in the internal circulation path C1 can flow into the refrigerant tank 17 through the path 15 provided with the opening / closing control valve 16, and thus pressurization by the pressure of the internal circulation pump 11 is not performed. Therefore, the pressure difference between the inlet and the outlet of the refrigerant flow path in the wafer mounting stage 24 is increased more, so that the cooling effect on the wafer mounting stage 24 due to the increase in the flow rate of the refrigerant flowing in the refrigerant flow path in the wafer mounting stage 24 is increased more.

[0075] In addition, in the chiller system 1 according to the present embodiment, based on the measurement result of the temperature sensor 23 provided in the external circulation path C2, the three-way valve 14 is used to open or close the connection path 19 connecting the internal circulation path C1 and the external circulation path C2, so that the cold refrigerant flowing in the internal circulation path C1 circulates within the internal circulation path C1 or flows into the external circulation path C2. Thereby, the temperature of the refrigerant flowing in the external circulation path C2 can be controlled within a specified range.

[0076] [Modification Example]

[0077] In the above-described embodiment, as a method for increasing the pumping pressure of the internal circulation pump 11, a case where the pressure control unit 42 controls the driving speed of the internal circulation pump 11 based on the pressure measured by the pressure sensor 26 is shown, but it is not limited thereto. For example, it may be configured that a throttle mechanism 28 is constituted by an electric drive valve (such as a solenoid valve or an electric valve) capable of adjusting the opening degree of the second branch path 27, and the opening degree of the electric drive valve is controlled based on the pressure measured by the pressure sensor 26.

[0078] In addition, as a method for increasing the pumping pressure of the internal circulation pump 11, it is also possible to use both a method of controlling the driving speed of the internal circulation pump 11 based on the pressure measured by the pressure sensor 26 and a method of controlling the opening degree of the electric drive valve constituting the throttle mechanism 28.

[0079] The embodiments of the present invention have been described above, but the present invention is not limited to the above examples, and various improvements and modifications can of course be made without departing from the gist of the present invention.

[0080] Description of Reference Numerals

[0081] 1: Chiller system; 10: Chiller unit; 11: Internal circulation pump; 12: Refrigerator; 13, 15: Path; 14: Three-way valve; 16: Opening / closing control valve; 17: Refrigerant tank; 18: Filter; 19: Connection path; 20: Supply path; 21: External circulation pump; 22: Heater; 23: Temperature sensor; 24: Wafer mounting table; 25: Return path; 26: Pressure sensor; 27: Second branch path; 28: Throttle mechanism; 29: First branch path; 30: Pressurization path; 31: Branch point; 40: Control device; C1: Internal circulation path; C2: External circulation path.

Claims

1. A cooling machine system that circulates a refrigerant between a wafer mounting stage and a cooling machine unit, wherein, the cooling machine system includes: an internal circulation path that enables the refrigerant to circulate inside the cooling machine unit; an external circulation path that enables the refrigerant to circulate between the cooling machine unit and the wafer mounting stage; and a control device that controls the cooling machine unit, a refrigerant tank, an internal circulation pump, and a refrigerator are provided in the internal circulation path, the external circulation path has a supply path that leads from the cooling machine unit to the wafer mounting stage and a return path that returns from the wafer mounting stage to the cooling machine unit, an external circulation pump and a temperature sensor are provided in the supply path, the return path has a communication path that connects the return path and the refrigerant tank, a throttling mechanism that restricts the flow rate of the refrigerant flowing into the refrigerant tank is provided in the communication path, an opening / closing control valve is provided in the internal circulation path at a position upstream of the refrigerant tank, the cooling machine system has a pressurization path for pressurizing the refrigerant flowing in the return path, and one end of the pressurization path is connected in the internal circulation path at a position upstream of the opening / closing control valve, and the other end of the pressurization path is connected in the communication path at a position upstream of the throttling mechanism, the control device controls the operation of the opening / closing control valve based on a temperature set value or a measurement result of the temperature sensor.

2. The cooling machine system according to claim 1, wherein, the control device closes the opening / closing control valve when the temperature set value or the temperature measured by the temperature sensor is equal to or higher than the boiling point of the refrigerant, or equal to or higher than the temperature obtained by subtracting a specified margin from the boiling point.

3. The cooling machine system according to claim 2, wherein, the control device opens the opening / closing control valve when the temperature set value or the temperature measured by the temperature sensor is less than the boiling point of the refrigerant, or less than the temperature obtained by subtracting a specified margin from the boiling point.

4. The cooling machine system according to claim 2 or 3, wherein, a pressure sensor is provided in the return path, the control device performs pressurization control of the return path based on the pressure measured by the pressure sensor when the temperature set value or the temperature measured by the temperature sensor is equal to or higher than the boiling point of the refrigerant.

5. The cooling machine system according to claim 4, wherein, the control device controls the operation of the internal circulation pump based on the pressure measured by the pressure sensor as the pressurization control.

6. The cooling machine system according to claim 4, wherein, the throttling mechanism is composed of an electric drive valve capable of adjusting the opening degree of the communication path, the control device controls the opening degree of the electric drive valve based on the pressure measured by the pressure sensor as the pressurization control.

7. The cooling machine system according to any one of claims 1 to 3, wherein, The chiller system has a connection path that is provided between the internal circulation path and the external circulation path and sends the refrigerant flowing in the internal circulation path to the external circulation path. A three-way valve is provided at the connection position where the internal circulation path is connected to the connection path. The control device controls the operation of the three-way valve based on the measurement result of the temperature sensor.

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