Chiller System

Abstract

To provide a cost- and space-saving chiller system that has high withstand voltage performance.SOLUTION: A chiller system 1 includes an internal circulation pathway C1, an external circulation pathway C2, and a control device 40. A refrigerant tank 17, an internal circulation pump 11, and a refrigerator 12 are provided to the internal circulation pathway C1. The external circulation pathway C2 has a feeding pathway 20 and a return pathway 25. An external circulation pump 21 and a temperature sensor 23 are provided to the feeding pathway 20. Throttling means 28 is provided to a communication pathway 27 creating communication between the return pathway 25 and the refrigerant tank 17. An on-off control valve 16 is provided to the internal circulation pathway C1. A pressurization pathway 30 has one end connected further upstream than the on-off control valve 16 in the internal circulation pathway C1 and the other end connected further upstream than the throttling means 28 in the communication pathway 27. The control device 40 controls operation of the on-off control valve 16 on the basis of a measurement result of the temperature sensor 23.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a chiller system, and more particularly to a chiller system that circulates a coolant between a wafer mounting stage in an inspection device that electrically inspects a plurality of chips formed on a wafer. [Background technology]

[0002] In the semiconductor manufacturing process, a prober is used to test the electrical characteristics of chips formed on a wafer. In recent years, the number of chips tested simultaneously has been increasing in order to shorten the testing time and reduce costs. Even if the chips are dynamic random access memories (DRAMs) or flash memories, which generate little heat, the amount of heat generated by the entire wafer during testing increases as the number of chips tested simultaneously increases.

[0003] Furthermore, chips are used in a wide range of applications, such as automotive chips, and the range of temperature environments during testing is expanding to ensure that chips function properly in the temperature environments required for those applications. As a result, the amount of heat generated by chips during testing increases in a wide range of temperature environments.

[0004] Therefore, various techniques have been proposed for controlling the temperature of the surface of the wafer mounting stage in a prober. For example, Patent Document 1 discloses a chiller mechanism for controlling the temperature of the wafer chuck (mounting stage) of a prober. This chiller mechanism has a cooling path and a coolant cooling path.

[0005] In the cooling path, a tank holding the cooling liquid and the wafer chuck are connected by a path from the tank to the wafer chuck and a path from the wafer chuck back to the tank, and the wafer chuck is cooled by circulating the cooling liquid between the tank and the wafer chuck using a pump installed on the cooling path.

[0006] In the coolant cooling path, the tank and the cooler are connected by a path from the tank to the cooler and a path from the cooler back to the tank, and the coolant cooled by the cooler is returned to the tank by a pump provided on the coolant cooling path. Furthermore, the temperature of the coolant held in the tank is adjusted by adjusting the amount of coolant circulating with a flow control valve provided on the coolant cooling path. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-311492 Summary of the Invention [Problem to be solved by the invention]

[0008] Incidentally, when a chiller mechanism such as the technique described in Patent Document 1 is applied to a prober that performs electrical testing at high temperatures, a fluorine-based inert liquid with a high boiling point has conventionally been used as the coolant.

[0009] This is because if the temperature of the coolant exceeds its boiling point, problems such as cavitation of the coolant may occur, making it impossible to control the temperature properly, or the impeller of the circulation pump may be damaged by the cavitation.

[0010] However, coolants with high boiling points tend to have higher kinetic viscosities at low temperatures due to their increased viscosity. This increases the flow rate of the coolant at low temperatures, resulting in a lower cooling effect on the wafer stage compared to coolants with low boiling points. Furthermore, the increased kinetic viscosity also increases the required shaft power of the circulation pump, resulting in increased power consumption.

[0011] For these reasons, a system is desired that can use a coolant with a low boiling point to ensure performance in low-temperature regions while delivering the coolant without boiling it even in high-temperature regions.One method for raising the boiling point of a coolant with a low boiling point is described in Patent Document 1, which applies pressure to the path of a chiller mechanism using compressed air or the like to raise the boiling point of the coolant.

[0012] However, with a configuration such as the chiller mechanism described in Patent Document 1, it is difficult to locally pressurize only the path from the wafer mounting table to the suction part of the circulation pump, which is the area that needs to be pressurized, so it is necessary to pressurize the entire path of the chiller mechanism via a tank or the like.

[0013] In this case, it is necessary to improve the pressure resistance of related equipment in the wetted parts, including auxiliary equipment. Because the equipment used must be constructed from stronger materials, the freedom in equipment selection is limited and the equipment becomes larger than before. This results in problems such as increased equipment costs. Furthermore, as the equipment becomes larger, the footprint of the chiller mechanism itself that houses this equipment also becomes larger than before.

[0014] The present invention has been made in view of the above circumstances, and has an object to provide a chiller system that is low cost, space-saving, and has high pressure resistance. [Means for solving the problem]

[0015] In order to solve the above problems, the following inventions are provided.

[0016] A chiller system according to a first aspect is a chiller system that circulates a coolant between a wafer mounting table and a chiller unit, and includes an internal circulation path that allows the coolant to circulate inside the chiller unit, an external circulation path that allows the coolant to circulate between the chiller unit and the wafer mounting table, and a control device that controls the chiller unit. The internal circulation path is provided with a coolant tank, an internal circulation pump, and a refrigerator. The external circulation path has a feed path from the chiller unit to the wafer mounting table and a return path from the wafer mounting table back to the chiller unit. The feed path is provided with an external circulation pump. and a temperature sensor, the return path has a communication path that connects the return path and the refrigerant tank, and the communication path is provided with a throttling means that limits the flow rate of refrigerant flowing into the refrigerant tank, the internal circulation path is provided with an on / off control valve upstream of the refrigerant tank, and a pressurization path for pressurizing the refrigerant flowing through the return path has a pressurization path having one end connected upstream of the on / off control valve in the internal circulation path and the other end connected upstream of the throttling means in the communication path, and the control device controls the operation of the on / off control valve based on the temperature setting value or the measurement result of the temperature sensor.

[0017] In the chiller system of the second aspect, in the first aspect, the control device closes the on-off 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 a temperature equal to or higher than the boiling point minus a predetermined margin.

[0018] A chiller system according to a third aspect is the second aspect, wherein the control device opens the on-off control valve when the temperature setpoint or the temperature measured by the temperature sensor is less than the boiling point of the refrigerant or a temperature less than the boiling point minus a predetermined margin.

[0019] A chiller system according to a fourth aspect is the chiller system of the second or third aspect, wherein a pressure sensor is provided in the return path, and the control device is configured to determine whether the temperature setpoint or the temperature measured by the temperature sensor is equal to or exceeds the boiling point of the refrigerant. ( Or, the boiling point minus a certain margin )If the pressure is equal to or greater than the pressure measured by the pressure sensor, pressure control is performed on the return path.

[0020] A chiller system according to a fifth aspect is the chiller system of the fourth aspect, 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.

[0021] A chiller system according to a sixth aspect is the chiller system of the fourth or fifth aspect, wherein the throttling means is constituted by an electrically driven valve capable of adjusting the opening of the communication path, and the control device controls the opening of the electrically driven valve based on the pressure measured by the pressure sensor as pressurization control.

[0022] A chiller system according to a seventh aspect is any one of the first to sixth aspects, and has a connection path provided between an internal circulation path and an external circulation path, and for sending refrigerant flowing through the internal circulation path to the external circulation path, a three-way valve provided at the connection point between the internal circulation path and the connection path, and a control device controls the operation of the three-way valve based on the measurement results of the temperature sensor.

[0023] An eighth aspect of the present invention provides a chiller system according to the seventh aspect, wherein the control device opens the connection path by the three-way valve when the temperature measured by the temperature sensor is higher than a predetermined value.

[0024] A ninth aspect of the present invention relates to the chiller system of the eighth aspect, wherein the control device closes the connection path with the three-way valve when the temperature measured by the temperature sensor is lower than a predetermined value.

[0025] The chiller system according to the tenth aspect is any one of the first to ninth aspects, in which a heater is provided in the feed path, and the control device controls the heater to heat the refrigerant based on the temperature measured by the temperature sensor. [Effects of the Invention]

[0026] According to the present invention, a chiller system having high pressure resistance can be realized at low cost and in a small space. [Brief explanation of the drawings]

[0027] [Figure 1] 1 is a schematic configuration diagram of a chiller system according to an embodiment of the present invention. [Figure 2] FIG. 2 is a functional block diagram of a control device. [Figure 3] 1 is a flowchart illustrating a control method for a chiller system. DETAILED DESCRIPTION OF THE INVENTION

[0028] Hereinafter, a chiller system according to an embodiment of the present invention will be described with reference to the accompanying drawings.

[0029] The schematic configuration of the chiller system according to this embodiment is shown in Fig. 1. As shown in Fig. 1, the chiller system 1 according to this embodiment includes a chiller unit 10 that circulates a refrigerant that cools the wafer mounting table 24, and a control device 40 that controls the entire chiller system 1.

[0030] Any liquid can be used as the refrigerant, but since a high kinematic viscosity increases the shaft power required for the circulation pump, it is preferable that the refrigerant be a liquid that has a relatively low viscosity at low temperatures. More specifically, the refrigerant is, for example, a fluorine-based inert liquid. More specific examples of fluorine-based inert liquids include Novec 7200 (boiling point 76°C at atmospheric pressure) manufactured by 3M and Galden 135 (boiling point 135°C at atmospheric pressure) manufactured by Solvay.

[0031] Refrigerants with relatively low viscosity at low temperatures tend to have low boiling points. Here, a low boiling point refers to a boiling point of, for example, about 70°C to about 140°C. Conversely, a high boiling point refers to a boiling point higher than, for example, about 150°C. Chiller system 1 can be suitably applied to probers that perform testing at high temperatures while taking advantage of the benefits of refrigerants with relatively low viscosity at low temperatures.

[0032] In the chiller system 1, the refrigerant paths are broadly divided into an internal circulation path C1 and an external circulation path C2. In FIG. 1, the internal circulation path C1 is indicated by a black arrow, and the external circulation path C2 is indicated by a white arrow. The direction of the arrow indicates the direction in which the refrigerant flows. In the following explanation, the base end of the arrow is defined as the upstream side of the refrigerant flow, and the tip end of the arrow is defined as the downstream side of the refrigerant flow.

[0033] The internal circulation path C1 allows the refrigerant to circulate between the refrigerant tank 17 and the refrigerator 12 inside the chiller unit 10. The external circulation path C2 allows the refrigerant to circulate between the chiller unit 10 and the wafer mounting table 24. When the chiller system 1 is used in a prober that performs testing at relatively high temperatures, the temperature of the refrigerant in the external circulation path C2 may reach a high temperature close to the boiling point of the refrigerant.

[0034] The configuration of the internal circulation path C1 will be described in detail below. The internal circulation path C1 is provided with a refrigerant tank 17, an internal circulation pump 11, and a refrigerator 12. 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 predetermined temperature.

[0035] A three-way valve 14 is provided downstream of the refrigerator 12, and the refrigerator 12 is fluidly connected to the three-way valve 14 by a path 13. The three-way valve 14 is fluidly connected to a refrigerant tank 17 by a path 15, and an on-off control valve 16 is provided on the path 15 upstream of the refrigerant tank 17. The on-off control valve 16 is an electrically driven valve such as a solenoid valve or an electric valve. Furthermore, a connection path 19 fluidly connects the three-way valve 14 to the suction port of the external circulation pump 21 of the external circulation path C2. In other words, the connection path 19 fluidly connects the internal circulation path C1 and the external circulation path C2.

[0036] In other words, the three-way valve 14 is provided at a connection position of the internal circulation path C1 between the path 13 from the refrigerator 12, the path 15 for returning the refrigerant to the refrigerant tank 17, and the connection path 19. By operating (controlling) the three-way valve 14, it is possible to switch between a state in which the path 13 and the connection path 19 are fluidly connected and the path 15 is closed, and a state in which the path 13 and the path 15 are fluidly connected and the connection path 19 is closed. Control of the three-way valve 14 will be described in detail later.

[0037] Next, the configuration of the external circulation path C2 will be described in detail. The external circulation path C2 is broadly divided into a feed path 20 and a return path 25. The feed path 20 is a path that supplies the refrigerant from the chiller unit 10 to the wafer mounting table 24. The return path 25 is a path that returns the refrigerant from the wafer mounting table 24 to the chiller unit 10.

[0038] An external circulation pump 21, a heater 22, and a temperature sensor 23 are provided in the feed path 20 in this order from the upstream side (the chiller unit 10 side) toward the wafer mounting table 24. The external circulation pump 21 sends out the coolant to the wafer mounting table 24. The heater 22 heats the coolant flowing through the feed path 20. The temperature sensor 23 measures the temperature of the coolant flowing through the feed path 20.

[0039] The wafer mounting stage 24 incorporates a coolant flow path (not shown). The coolant flow path is fluidly connected to the feed path 20 and the return path 25. As the coolant adjusted to an appropriate temperature flows through the coolant flow path, the surface temperature of the wafer mounting stage 24 is controlled to a temperature suitable for inspection by a prober (inspection device). The configuration of the wafer mounting stage 24 with a coolant flow path is well known, so a detailed explanation will be omitted. The coolant that passes through the coolant flow path of the wafer mounting stage 24 returns to the chiller unit 10 via the return path 25.

[0040] The return path 25 branches into a first branch path 29 and a second branch path 27 at a branch point 31 in the chiller unit 10. The first branch path 29 is fluidly connected to the feed path 20 downstream of the three-way valve 14 and upstream of the external circulation pump 21. A pressure sensor 26 is provided on the first branch path 29 to measure the pressure of the refrigerant in the return path 25 (specifically, in the first branch path 29).

[0041] The second branch path 27 is connected to the refrigerant tank 17, and a throttling means 28 is provided on the second branch path 27 upstream of the refrigerant tank 17. The throttling means 28 is configured with an orifice (throttling portion) that narrows the flow path cross section in the second branch path 27, and this orifice limits the flow rate of the refrigerant flowing through the second branch path 27. Note that the throttling means 28 may be configured with an electrically driven valve such as a solenoid valve or an electric valve, as in a modified example described below. The second branch path 27 corresponds to the "communication path" of the present invention. Note that in the present invention, the "communication path" is used in a broad sense to include not only the second branch path 27 but also the first branch path 29 that communicates with the refrigerant tank 17 via the second branch path 27 and the return path 25 from which the first branch path 29 and the second branch path 27 branch.

[0042] Furthermore, a pressurizing path 30 for pressurizing the return path 25 is provided between the internal circulation path C1 and the external circulation path C2. One end of the pressurizing path 30 (on the internal circulation path C1 side) is located on the path 15 of the internal circulation path C1, more specifically, between the three-way valve 14 and the on / off control valve 16 (i.e., upstream of the on / off control valve 16). The other end of the pressurizing path 30 (on the external circulation path C2 side) is located on the second branch path 27, more specifically, between the throttle means 28 and the branch point 31 (i.e., upstream of the throttle means 28). The other end of the pressurizing path 30 is not limited to being located on the second branch path 27, and may be located on the first branch path 29, for example.

[0043] Additionally, a filter 18 is provided in the refrigerant tank 17. Depending on the characteristics of the refrigerant, when the temperature rises above the boiling point, the refrigerant in the external circulation path C2 may thermally decompose, producing hazardous substances such as acids. Therefore, the chiller system 1 of this embodiment is provided with a filter 18 that adsorbs hazardous substances produced in the refrigerant. It is desirable to provide this filter 18 in a position that is not easily exposed to high temperatures. Specifically, for example, the filter 18 is provided inside the refrigerant tank 17 (see FIG. 1). However, this example is not intended to limit the position of the filter 18.

[0044] When a low-boiling-point refrigerant is used in the chiller system 1, it is necessary to suppress cavitation of the refrigerant. In this embodiment, the control device 40 (described later) controls each component of the chiller system 1 (the three-way valve 14, the heater 22, the on-off control valve 16, and the internal circulation pump 11) based on the measurement results of the temperature sensor 23 and the pressure sensor 26. This allows the return path 25 of the external circulation path C2 to be locally pressurized via the pressurization path 30, thereby suppressing refrigerant cavitation and enabling the chiller system 1 to operate satisfactorily. This allows for the realization of a system that can deliver a refrigerant without boiling even in high-temperature regions while ensuring performance in low-temperature regions using a refrigerant with a low boiling point, without incurring the cost and increasing the size of the device required to improve pressure resistance.

[0045] Next, the functional configuration of the control device 40 will be described using Fig. 2. As shown in Fig. 2, 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 unit of the chiller system 1.

[0046] The temperature control unit 41 controls the switching of the three-way valve 14 and the heating of the heater 22 based on the temperature of the refrigerant in the feed path 20 of the external circulation path C2 measured by the temperature sensor 23 so that the refrigerant in the external circulation path C2 has a temperature within a predetermined range.

[0047] 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 feed path 20 of the external circulation path C2 measured by the temperature sensor 23. Furthermore, 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. In this way, 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.

[0048] Each component (main control unit 43, temperature control unit 41, and pressure control unit 42) constituting control device 40 is realized by, for example, a personal computer, a workstation, or a programmable logic controller (PLC). Control device 40 includes a central processing unit (CPU) that controls the operation of each device constituting chiller system 1, a read-only memory (ROM), a storage device (for example, a hard disk drive (HDD) or a solid state drive (SSD)) that stores a control program, and a synchronous dynamic random access memory (SDRAM) that can be used as a working area for the CPU.

[0049] Furthermore, the control device 40 receives operation input from an operator via an operation unit (not shown) and controls the operation of each device by transmitting control signals corresponding to the operation input to each component of the chiller system 1. The operation unit includes, for example, a keyboard, a mouse, or a touch panel.

[0050] Next, a control method for chiller system 1 will be described with reference to Fig. 3. First, control device 40 uses temperature sensor 23 to measure the temperature of the coolant flowing through feed path 20 (step S10). Here, the temperature measured by temperature sensor 23 indicates a temperature that is approximately (substantially) equal to the temperature of the coolant supplied to wafer mounting table 24. Next, temperature control unit 41 of control device 40 determines whether the coolant temperature measured in step S10 is greater than a predetermined value (step S12).

[0051] If the temperature of the refrigerant is higher than the predetermined value (step S12: YES), temperature control unit 41 drives three-way valve 14 to connect path 13 on the refrigerator 12 side with connection path 19 and closes path 15 on the refrigerant tank 17 side (step S14). That is, temperature control unit 41 opens connection path 19 using three-way valve 14. Thereafter, the process proceeds to step S22.

[0052] In the internal circulation path C1, a refrigerant cooled by the refrigerator 12 and maintained at a constant low temperature circulates. If the temperature of the refrigerant measured in step S10 is higher than a predetermined value (set value), the temperature of the refrigerant flowing through the external circulation path C2 needs to be lowered. The temperature control unit 41 uses the three-way valve 14 to connect the path 13 on the refrigerator 12 side with the connection path 19, and closes the path 15 on the refrigerant tank 17 side. This mixes the low-temperature refrigerant flowing through the internal circulation path C1 with the high-temperature refrigerant flowing through the external circulation path C2, lowering the temperature of the refrigerant flowing through the external circulation path C2.

[0053] The mixing ratio of the low-temperature refrigerant flowing through the internal circulation path C1 and the high-temperature refrigerant flowing through the external circulation path C2 in the three-way valve 14 is set by the temperature control unit 41 appropriately according to the temperature of the refrigerant measured in step S10.

[0054] On the other hand, if the refrigerant temperature measured in step S10 is equal to or lower than the predetermined value (step S12: NO), there is no need to lower the refrigerant temperature, so temperature control unit 41 uses three-way valve 14 to connect path 13 on the chiller 12 side with path 15 on the refrigerant tank 17 side, and closes connecting path 19 (step S16). This prevents the low-temperature refrigerant flowing through internal circulation path C1 from flowing into external circulation path C2 via connecting path 19. While chiller system 1 is operating, the refrigerant temperature measured by temperature sensor 23 is fed back to temperature control unit 41, and temperature control unit 41 continuously controls three-way valve 14 based on this feedback.

[0055] After step S16, the temperature control unit 41 determines whether the refrigerant temperature measured in step S10 is within a predetermined range, thereby determining whether the refrigerant should be heated (step S18). If the refrigerant temperature is not within the predetermined temperature range (step S18: YES), the refrigerant temperature in the external circulation path C2 is too low and the refrigerant needs to be heated. Therefore, the temperature control unit 41 heats the refrigerant using the heater 22 (step S20) and proceeds to step S22. On the other hand, if the refrigerant temperature is within the predetermined temperature range (step S18: NO), the refrigerant temperature in the external circulation path C2 is too low and the refrigerant needs to be heated. Addition Since heat is not required, the process of step S20 (heating of the refrigerant by heater 22) is not performed and the process proceeds to step S22.

[0056] Next, in step S22, the pressure control unit 42 of the control device 40 determines whether the refrigerant temperature or the set refrigerant temperature is equal to or higher than the boiling point of the refrigerant in the environment of the external circulation path C2. The refrigerant temperature used in this determination is preferably the refrigerant temperature measured by the temperature sensor 23 immediately before step S22 is performed. The refrigerant temperature measured in step S10 may also be used. If the refrigerant temperature or the set refrigerant temperature 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 through the internal circulation path C1 flows into the second branch path 27 via the pressurizing path 30, and the flow rate of the refrigerant toward the refrigerant tank 17 is restricted by the throttling means 28, so that the pressure in the return path 25 of the external circulation path C2 increases.

[0057] Here, when the on-off control valve 16 is closed (step S24), the second branch path 27 is narrowed by the throttle means 28, so the path from the wafer mounting table 24 to the suction port of the external circulation pump 21 (i.e., the return path 2) is narrowed. 5 ) also increases the pushing pressure required to send the refrigerant from the internal circulation path C1 side.

[0058] Therefore, the pressure control unit 42 increases the driving rotation 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 pushing pressure of the internal circulation pump 11, which is performed via the pressurizing path 30 (step S26). Note that the internal circulation pump 11 is preferably configured as an inverter-driven pump.

[0059] By narrowing a portion of the refrigerant path (second branch path 27) toward the refrigerant tank 17 using the throttle means 28 and increasing the pushing pressure of the internal circulation pump 11, the pressure in the return path 25 of the external circulation path C2 can be increased to or above the vapor pressure of the refrigerant. This allows the refrigerant to circulate well in the external circulation path C2 while suppressing cavitation of the refrigerant.

[0060] The pressure control described above is performed on the path from the outlet of the coolant flow path in the wafer mounting table 24 to the suction port of the external circulation pump 21 (i.e., the return path 25) because the pressure is prone to drop, but the feed path 20 is pressurized from the beginning because it is subjected to the discharge pressure of the external circulation pump 21. Therefore, no special mechanism is provided for the feed path 20 to prevent pressure drop.

[0061] On the other hand, if the temperature of the refrigerant or the set temperature of the refrigerant is lower than the boiling point of the refrigerant (step S22: NO), the control device 40 opens the on-off control valve 16 (step S28). 1 5 and into the coolant tank 17, no pressure is applied by the compression pressure of the internal circulation pump 11 within the range of the path from the wafer mounting table 24 to the suction port of the external circulation pump 21 (i.e., within the return path 25 of the external circulation path C2). Since no pressure is applied by the compression pressure of the internal circulation pump 11, a larger pressure difference can be obtained between the inlet and outlet of the coolant flow path in the wafer mounting table 24, and therefore a larger cooling effect on the wafer mounting table 24 can be obtained by increasing the flow rate of the coolant flowing through the coolant flow path in the wafer mounting table 24.

[0062] The control device 40 repeats the processes of steps S10 to S28 (step S30) while the chiller system 1 is operating. This allows the chiller system 1 to operate satisfactorily while suppressing cavitation of the refrigerant.

[0063] In this embodiment, the pressure control unit 42 determines whether to open or close the on-off control valve 16 based on whether the refrigerant temperature or the set refrigerant temperature is equal to or higher than the boiling point of the refrigerant. However, to ensure that the external circulation pump 21 does not cause cavitation, the refrigerant must be pressurized to a value equal to or higher than the saturated vapor pressure of the refrigerant, and it is also necessary to consider the reduced pressure at the suction part of the external circulation pump 21. Therefore, it is also possible to determine whether to open or close the on-off control valve 16 based on whether the refrigerant temperature or the set refrigerant temperature is equal to or higher than the boiling point of the refrigerant minus a predetermined margin that takes these pressure fluctuations into consideration.

[0064] [effect] As described above, according to the chiller system 1 of this embodiment, the external circulation path C 2 By controlling the operation of the on-off control valve 16 provided in the internal circulation path C1 based on the measurement results of the temperature sensor 23 provided in the internal circulation path C1, it becomes possible to locally pressurize a portion of the external circulation path C2 (return path 25) via the pressurization path 30, thereby suppressing refrigerant cavitation and enabling the chiller system 1 to operate satisfactorily. This makes it possible to realize a system that can use a refrigerant with a low boiling point to ensure performance in low-temperature ranges while sending the refrigerant without boiling even in high-temperature ranges, without incurring the costs and increased size of the device that would be required to improve pressure-resistant performance. As a result, a chiller system with high pressure-resistant performance can be realized at low cost and in a small space.

[0065] Specifically, when the set temperature of the coolant or the temperature measured by the temperature sensor 23 is equal to or higher than the boiling point of the coolant, the on-off control valve 16 is closed, and the pressure path 30 applies pressure to the area within the path from the wafer mounting table 24 to the intake port of the external circulation pump 21 (i.e., within the return path 25 of the external circulation path C2) by the pushing pressure of the internal circulation pump 11. 2 The driving rotation speed of the internal circulation pump 11 is increased based on the measurement result of the pressure sensor 26 provided in the internal circulation path C2, thereby increasing the pushing pressure of the internal circulation pump 11. This increases the pressure in the return path 25 of the external circulation path C2, making it possible to suppress cavitation of the refrigerant.

[0066] 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 on-off control valve 16 is opened, so that the refrigerant flowing through the internal circulation path C1 is circulated through the path in which the on-off control valve 16 is provided. 1 5 and flows into the coolant tank 17, so that pressurization by the pushing pressure of the internal circulation pump 11 is not performed. Therefore, a larger pressure difference can be obtained between the inlet and outlet of the coolant flow path in the wafer mounting table 24, and the flow rate of the coolant flowing through the coolant flow path in the wafer mounting table 24 increases, thereby achieving a greater cooling effect on the wafer mounting table 24.

[0067] Furthermore, according to the chiller system 1 of this embodiment, the external circulation path C 2 Based on the measurement results of the temperature sensor 23 provided in the refrigerant coolant coolant coolant flowing through the internal circulation path C1 is circulated within the internal circulation path C1 or is caused to flow into the external circulation path C2 by opening or closing the connection path 19 connecting the internal circulation path C1 and the external circulation path C2 using the three-way valve 14. This makes it possible to control the temperature of the refrigerant flowing through the external circulation path C2 within a predetermined range.

[0068] [Variations] In the above embodiment, the method of increasing the pumping pressure of the internal circulation pump 11 is described as a case where the pressure control unit 42 controls the drive rotation speed of the internal circulation pump 11 based on the pressure measured by the pressure sensor 26. However, this is not limited to this. For example, the throttling means 28 may be configured as an electrically driven valve (solenoid valve, electric valve, etc.) capable of adjusting the opening degree of the second branch path 27, and the opening degree of the electrically driven valve may be controlled based on the pressure measured by the pressure sensor 26.

[0069] In addition, as a method for increasing the pushing pressure of the internal circulation pump 11, it is possible to use both a combination of controlling the driving rotation speed of the internal circulation pump 11 based on the pressure measured by the pressure sensor 26 and controlling the opening degree of the electrically driven valve that constitutes the throttling means 28.

[0070] Although the embodiments of the present invention have been described above, the present invention is not limited to the above examples, and various improvements and modifications may be made without departing from the spirit of the present invention. [Explanation of symbols]

[0071] 1...chiller system, 10...chiller unit, 11...internal circulation pump, 12...refrigerator, 13, 15...path, 14...three-way valve, 16...on / off control valve, 17...refrigerant tank, 18...filter, 19...connection path, 20...feed path, 21...external circulation pump, 22...heater, 23...temperature sensor, 24...wafer mounting table, 25...return path road, 26...pressure sensor, 27...second branch path, 28...throttling means, 29...first branch path, 30...pressurizing path, 31...branch point, 40...control device, C1...internal circulation path, C2...external circulation path

Claims

1. A chiller system that circulates a coolant between a wafer mounting table and a chiller unit, an internal circulation path that allows the refrigerant to circulate inside the chiller unit; an external circulation path that allows the coolant to circulate between the chiller unit and the wafer mounting table; a control device that controls the chiller unit; Equipped with The internal circulation path is provided with a refrigerant tank, an internal circulation pump, and a refrigerator, the external circulation path includes a feed path from the chiller unit to the wafer mounting table and a return path from the wafer mounting table back to the chiller unit; The feed path is provided with an external circulation pump and a temperature sensor, the return path has a communication path that communicates between the return path and the refrigerant tank, a throttle means for restricting the flow rate of the refrigerant flowing into the refrigerant tank is provided in the communication path; an on-off control valve is provided in the internal circulation path upstream of the refrigerant tank; a pressurization path for pressurizing the refrigerant flowing through the return path, the pressurization path having one end connected to the internal circulation path upstream of the on-off control valve and the other end connected to the communication path upstream of the throttling means; the control device controls the operation of the on-off control valve based on a temperature setting value or a measurement result of the temperature sensor. Chiller system.

2. The control device closes the on-off control valve when the temperature setting value or the temperature measured by the temperature sensor is equal to or higher than the boiling point of the refrigerant or a temperature obtained by subtracting a predetermined margin from the boiling point. The chiller system of claim 1 .

3. The control device opens the on-off control valve when the temperature setting value or the temperature measured by the temperature sensor is lower than the boiling point of the refrigerant or a temperature obtained by subtracting a predetermined margin from the boiling point. The chiller system of claim 2 .

4. a pressure sensor is provided in the return path; When the temperature setting value or the temperature measured by the temperature sensor is equal to or higher than the boiling point of the refrigerant, the control device executes pressurization control for the return path based on the pressure measured by the pressure sensor. The chiller system according to claim 2 or 3.

5. The control device controls the operation of the internal circulation pump based on the pressure measured by the pressure sensor as the pressurization control. The chiller system of claim 4.

6. the throttle means is configured by 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 the pressurization control. The chiller system according to claim 4 or 5.

7. a connection path provided between the internal circulation path and the external circulation path, for sending the refrigerant flowing through the internal circulation path to the external circulation path; a three-way valve is provided at a connection position between the internal circulation path and the connection path; The control device controls the operation of the three-way valve based on the measurement result of the temperature sensor. The chiller system according to any one of claims 1 to 6.

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