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 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, the electrical characteristics of chips formed on a wafer are inspected by a prober. In recent years, in order to shorten the inspection time and reduce costs, the number of chips inspected simultaneously has been increasing. For example, even when the chips are DRAM (Dynamic Random Access Memory) or flash memory with a small heat generation amount, when the number of chips inspected simultaneously increases, the heat generation amount generated from the entire wafer during inspection increases.

[0003] In addition, chips such as in-vehicle chips are used in a wide range of applications, and in order to ensure that the chips operate normally even in a temperature environment according to their applications, the range of the temperature environment during inspection is also expanding. Therefore, the heat generation amount of the chips during inspection is increasing under a wide range of temperature environments.

[0004] Therefore, conventionally, various techniques for controlling the temperature of the surface of a mounting stage on which a wafer is mounted in a prober have been proposed. For example, Patent Document 1 discloses a chiller mechanism for controlling the temperature of a 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 for holding a coolant and a 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 coolant is circulated between the tank and the wafer chuck by a pump provided on the cooling path to cool the wafer chuck.

[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. The coolant cooled by the cooler is returned to the tank by a pump installed in the coolant cooling path. Furthermore, the temperature of the coolant held in the tank is adjusted by controlling the amount of coolant circulating using a flow control valve installed in the coolant cooling path. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2008-311492 [Overview of the project] [Problems that the invention aims to solve]

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

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

[0010] However, coolants with high boiling points tend to increase in viscosity at low temperatures, which in turn increases their kinematic viscosity. Therefore, in the low-temperature range, the increased kinematic viscosity reduces the flow rate of the coolant, resulting in a reduced cooling effect on the wafer mounting platform compared to coolants with low boiling points. In addition, the increased kinematic viscosity also leads to an increase in the required shaft power of the circulation pump, resulting in increased power consumption.

[0011] For these reasons, a system is desired that can ensure performance in low-temperature regions by using a coolant with a low boiling point, while also being able to deliver 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 to apply pressure to the path of the chiller mechanism described in Patent Document 1 using compressed air or the like to raise the boiling point of the coolant.

[0012] However, in a chiller mechanism like the one described in Patent Document 1, it is difficult to locally pressurize only the path from the wafer mounting platform to the suction section of the circulation pump, which is the part that needs to be pressurized. Therefore, it is necessary to pressurize the entire path of the chiller mechanism via a tank or the like.

[0013] In this case, it becomes necessary to improve the pressure resistance of the related equipment, including auxiliary components, in the wetted parts. To construct the equipment using stronger materials, the freedom of equipment selection becomes more limited compared to conventional methods, and the equipment becomes larger. As a result, the equipment cost increases. Furthermore, the increased size of the equipment also leads to an increased footprint for the chiller mechanism itself compared to conventional methods.

[0014] This invention has been made in view of these circumstances, and aims to provide a chiller system that is low-cost, space-saving, and has high pressure resistance performance. [Means for solving the problem]

[0015] To solve the above problems, the following invention is provided.

[0016] The chiller system according to the first embodiment is a chiller system that circulates a refrigerant between a wafer mounting table and a chiller unit, comprising: an internal circulation path that enables the circulation of the refrigerant inside the chiller unit; an external circulation path that enables the circulation of the refrigerant between the chiller unit and the wafer mounting table; and a control device that controls the chiller unit, wherein the internal circulation path is provided with a refrigerant tank, an internal circulation pump, and a chiller, and the external circulation path has a supply path from the chiller unit to the wafer mounting table and a return path that returns from the wafer mounting table to the chiller unit, and the supply path is provided with an external circulation pump A temperature sensor and a return path are provided, the return path has a communication path that connects the return path and the refrigerant tank, the communication path is provided with a throttling means to limit the flow rate of refrigerant into the refrigerant tank, the internal circulation path has an on / off control valve upstream of the refrigerant tank, and a pressurizing path for pressurizing the refrigerant flowing through the return path has a pressurizing path which has 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 set value or the measurement result of the temperature sensor.

[0017] In the chiller system according to the second embodiment, 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 greater than the boiling point of the refrigerant or a temperature obtained by subtracting a predetermined margin from the boiling point.

[0018] In the third embodiment of the chiller system, in the second embodiment, the control device opens the on / off 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 the boiling point minus a predetermined margin.

[0019] In the fourth embodiment of the chiller system, in the second or third embodiment, a pressure sensor is provided in the return path, and the control device performs pressurization control on the return path based on the pressure measured by the pressure sensor if the temperature set value or the temperature measured by the temperature sensor is equal to or greater than the boiling point of the refrigerant or a temperature obtained by subtracting a predetermined margin from the boiling point.

[0020] In the chiller system according to the fifth aspect, in the fourth aspect, as pressure control, the control device controls the operation of the internal circulation pump based on the pressure measured by the pressure sensor.

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

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

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

[0024] In the chiller system according to the ninth aspect, in the eighth aspect, when the temperature measured by the temperature sensor is lower than a predetermined value, the control device closes the connection path by the three-way valve.

[0025] In the chiller system according to the tenth aspect, in any one of the first to ninth aspects, a heater is provided in the feed path, and the control device controls heating the refrigerant by the heater based on the temperature measured by the temperature sensor. [[ID=2,3]]

Advantages of the Invention

[0026] According to the present invention, a chiller system having high pressure resistance performance can be realized at low cost and with space saving.

Brief Description of the Drawings

[0027] [Figure 1] This is a schematic diagram of the chiller system according to this embodiment. [Figure 2] This is a functional block diagram of the control unit. [Figure 3] This flowchart shows the control method for the chiller system. [Modes for carrying out the invention]

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

[0029] Figure 1 shows a schematic configuration of the chiller system according to this embodiment. As shown in Figure 1, the chiller system 1 according to this embodiment includes a chiller unit 10 that circulates a refrigerant to cool the wafer mounting stage 24, and a control device 40 that controls the entire chiller system 1.

[0030] Any liquid can be used as a 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 with relatively low viscosity at low temperatures. More specifically, the refrigerant is, for example, a fluorinated inert liquid. More specifically, examples of fluorinated inert liquids include Novek 7200 from 3M (boiling point 76°C at atmospheric pressure) and Galden 135 from Solvay (boiling point 135°C at atmospheric pressure).

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

[0032] In chiller system 1, the refrigerant path is broadly divided into an internal circulation path C1 and an external circulation path C2. In Figure 1, the internal circulation path C1 is shown by a black arrow, and the external circulation path C2 is shown by a white arrow. The direction of the arrows indicates the direction of refrigerant flow. In the following explanation, the base end of the arrow is considered the upstream side of the refrigerant flow, and the tip end of the arrow is considered 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 chiller 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 stage 24. When the chiller system 1 is used in a prober that performs inspections at relatively high temperatures, the temperature of the refrigerant in the external circulation path C2 may reach high temperatures 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 equipped with a refrigerant tank 17, an internal circulation pump 11, and a chiller 12. The refrigerant tank 17 stores the refrigerant. The internal circulation pump 11 sends the refrigerant supplied from the refrigerant tank 17 to the chiller 12. The chiller 12 cools the refrigerant to a predetermined temperature.

[0035] A three-way valve 14 is provided downstream of the chiller 12, and the chiller 12 and the three-way valve 14 are fluidly connected via a path 13. The three-way valve 14 is fluidly connected to the refrigerant tank 17 via 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 composed of an electrically driven valve such as a solenoid valve or an electric valve. Furthermore, the three-way valve 14 is fluidly connected to the suction port of the external circulation pump 21 of the external circulation path C2 via a connecting path 19. In other words, the connecting 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 installed at the connection point between the internal circulation path C1, the path 13 from the chiller 12, the path 15 that returns 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 path 13 and the connection path 19 are fluidly connected and path 15 is blocked, and a state in which path 13 and path 15 are fluidly connected and the connection path 19 is blocked. The control of the three-way valve 14 will be described in more detail later.

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

[0038] The supply path 20 is equipped with an external circulation pump 21, a heater 22, and a temperature sensor 23, arranged in order from the upstream side (chiller unit 10 side) toward the wafer mounting stage 24. The external circulation pump 21 supplies refrigerant to the wafer mounting stage 24. The heater 22 heats the refrigerant flowing through the supply path 20. The temperature sensor 23 measures the temperature of the refrigerant flowing through the supply path 20.

[0039] The wafer mounting platform 24 incorporates a refrigerant flow path (not shown). The refrigerant flow path is fluidly connected to a supply path 20 and a return path 25. As the refrigerant, adjusted to an appropriate temperature, flows through the refrigerant flow path, the surface temperature of the wafer mounting platform 24 is controlled to a temperature suitable for inspection by the prober (inspection device). The configuration of the wafer mounting platform 24 with a refrigerant flow path is well known, so a detailed explanation is omitted. The refrigerant that has passed through the refrigerant flow path of the wafer mounting platform 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 branching 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 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 composed of an orifice (throttling section) that narrows the cross-section of the flow path in the second branch path 27, and this orifice limits the flow rate of the refrigerant flowing through the second branch path 27. The throttling means 28 may be composed of an electrically driven valve such as a solenoid valve or an electric valve, as shown in the modified example described later. The second branch path 27 corresponds to the "communication path" of the present invention. In the present invention, the term "communication path" is used as a broad concept that includes not only the second branch path 27, but also the first branch path 29 which communicates with the refrigerant tank 17 via the second branch path 27, and the return path 25 which is the source of the branching of the first branch path 29 and the second branch path 27.

[0042] Furthermore, a pressurizing path 30 is provided between the internal circulation path C1 and the external circulation path C2 to pressurize the return path 25. One end of the pressurizing path 30 (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 (the external circulation path C2 side) is located on the second branch path 27, more specifically between the throttling means 28 and the branch point 31 (i.e., upstream of the throttling means 28). Note that the other end of the pressurizing path 30 is not limited to the second branch path 27, but may also be located on the first branch path 29, for example.

[0043] Furthermore, a filter 18 is provided in the refrigerant tank 17. Depending on the characteristics of the refrigerant, if the temperature exceeds the boiling point, the refrigerant in the external circulation path C2 may undergo thermal decomposition, generating harmful substances such as acids. Therefore, the chiller system 1 of this embodiment is provided with a filter 18 that adsorbs harmful substances generated in the refrigerant. It is desirable that this filter 18 be installed in a location that is not easily exposed to high temperatures. Specifically, for example, the filter 18 is installed inside the refrigerant tank 17 (see Figure 1). However, this example is not intended to limit the location of the filter 18.

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

[0045] Next, the functional configuration of the control device 40 will be explained using Figure 2. As shown in Figure 2, the control device 40 comprises 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.

[0046] 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 external circulation path C2 is within a predetermined temperature 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.

[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 supply path 20 of the external circulation path C2, as 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, as 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 to suppress cavitation of the refrigerant.

[0048] Each component of the control device 40 (main control unit 43, temperature control unit 41, and pressure control unit 42) is implemented by, for example, a personal computer, workstation, or PLC (Programmable Logic Controller). The control device 40 includes a CPU (Central Processing Unit) that controls the operation of each device constituting the chiller system 1, ROM (Read Only Memory), a storage device (for example, an HDD (Hard Disk Drive) or SSD (Solid State Drive)) that stores the control program, and SDRAM (Synchronous Dynamic Random Access Memory) that can be used as a workspace for the CPU.

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

[0050] Next, the control method for the chiller system 1 will be explained using Figure 3. First, the control device 40 measures the temperature of the refrigerant flowing through the supply path 20 using the temperature sensor 23 (step S10). Here, the temperature measured by the temperature sensor 23 is approximately (substantially) equal to the temperature of the refrigerant supplied to the wafer mounting stage 24. Subsequently, 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 predetermined value (step S12).

[0051] If the refrigerant temperature is greater than a predetermined 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 with the connection path 19, and closes the path 15 on the refrigerant tank 17 side (step S14). In other words, the temperature control unit 41 opens the connection path 19 with the three-way valve 14. The process then proceeds to step S22.

[0052] In the internal circulation path C1, refrigerant cooled by the chiller 12 and kept at a constant low temperature circulates. If the temperature of the refrigerant measured in step S10 is greater than a predetermined 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 connects the path 13 on the chiller 12 side with the connection path 19 using the three-way valve 14, and closes the path 15 on the refrigerant tank 17 side. This mixes the low-temperature refrigerant flowing in the internal circulation path C1 with the high-temperature refrigerant flowing in the external circulation path C2, thereby lowering the temperature of the refrigerant flowing in 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 appropriately set by the temperature control unit 41 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 below a predetermined value (step S12: NO), there is no need to lower the refrigerant temperature, so the temperature control unit 41 connects the path 13 on the chiller 12 side and the path 15 on the refrigerant tank 17 side using the three-way valve 14 and closes the connection path 19 (step S16). This prevents the low-temperature refrigerant flowing through the internal circulation path C1 from flowing into the external circulation path C2 via the connection path 19. During operation of the chiller system 1, the temperature control unit 41 receives feedback of the refrigerant temperature measured by the temperature sensor 23, and based on this, the temperature control unit 41 continuously controls the three-way valve 14.

[0055] After step S16, the temperature control unit 41 determines whether or not to heat the refrigerant by determining whether or not the refrigerant temperature measured in step S10 is within a predetermined range (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 therefore needs to be heated. In this case, 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), heating the refrigerant temperature in the external circulation path C2 is unnecessary, so the process in step S20 (heating the refrigerant with the 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 temperature of the refrigerant or the set temperature of the refrigerant is equal to or greater than the boiling point of the refrigerant in the environment of the external circulation path C2. Preferably, the temperature of the refrigerant used in this determination is the temperature of the refrigerant measured by the temperature sensor 23 immediately before step S22 is performed. Alternatively, the temperature of the refrigerant measured in step S10 may be used. If the temperature of the refrigerant or the set temperature of the refrigerant is equal to or greater 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 to the second branch path 27 side via the pressurized path 30, and the flow rate of the refrigerant toward the refrigerant tank 17 is restricted by the throttling means 28, so the pressure in the return path 25 of the external circulation path C2 increases.

[0057] In this case, if the on / off control valve 16 is closed (step S24), the second branch path 27 is narrowed by the throttling means 28, and therefore the push pressure required to send refrigerant from the internal circulation path C1 side to the path from the wafer mounting stage 24 to the intake port of the external circulation pump 21 (i.e., the return path 20) also increases.

[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 via the pressurizing path 30 (step S26). It is preferable that the internal circulation pump 11 is configured as an inverter-driven pump.

[0059] By narrowing a portion of the refrigerant path (second branch path 27) leading to the refrigerant tank 17 using the throttling means 28, and by 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 raised to a level above the vapor pressure of the refrigerant. This allows the refrigerant to circulate well within the external circulation path C2 while suppressing cavitation of the refrigerant.

[0060] Although pressure control is performed as described above in the path from the outlet of the refrigerant flow path in the wafer mounting stage 24 to the inlet of the external circulation pump 21 (i.e., the return path 25) because the pressure tends to drop there, the supply path 20 is pressurized from the start because of the discharge pressure of the external circulation pump 21. For this reason, no mechanism is provided in the supply 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 below the boiling point of the refrigerant (step S22: NO), the control device 40 opens the on / off control valve 16 (step S28). As a result, the refrigerant flowing through the internal circulation path C1 can flow into the refrigerant tank 17 via the path 25 where the on / off control valve 16 is provided, so that the internal circulation pump 11 does not pressurize the area within the path from the wafer mounting stage 24 to the inlet of the external circulation pump 21 (i.e., within the return path 25 of the external circulation path C2). And because the internal circulation pump 11 does not pressurize the area, a larger pressure difference is obtained between the inlet and outlet of the refrigerant flow path in the wafer mounting stage 24, and a greater cooling effect on the wafer mounting stage 24 is obtained due to the increased flow rate of the refrigerant flowing through the refrigerant flow path in the wafer mounting stage 24.

[0062] The control device 40 repeats the process from step S10 to step S28 while the chiller system 1 is in operation (step S30). This allows the chiller system 1 to operate smoothly while suppressing cavitation of the refrigerant.

[0063] In this embodiment, the case in which the pressure control unit 42 decides whether to open or close the on / off control valve 16 based on whether the refrigerant temperature or the set temperature of the refrigerant is equal to or greater than the boiling point of the refrigerant has been described. However, in order to ensure that the external circulation pump 21 does not cause cavitation, it is necessary to pressurize the refrigerant to a level above the saturated vapor pressure, and furthermore, it is necessary to consider the depressurization at the suction part of the external circulation pump 21. Therefore, the opening and closing of the on / off control valve 16 may also be decided based on whether the refrigerant temperature or the set temperature of the refrigerant is equal to or greater than the boiling point of the refrigerant minus a predetermined margin that takes these pressure fluctuations into account.

[0064] [effect] As described above, according to the chiller system 1 of this embodiment, 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 external circulation path C1, it is possible to locally pressurize a part of the external circulation path C2 (return path 25) via the pressurization path 30, thereby suppressing cavitation of the refrigerant and enabling smooth operation of the chiller system 1. This makes it possible to realize a system that can deliver refrigerant without boiling it even in the high-temperature range, while ensuring performance in the low-temperature range using a refrigerant with a low boiling point, without incurring the costs and increasing the size of the equipment required to improve pressure resistance. As a result, a chiller system with high pressure resistance can be realized at low cost and in a small space.

[0065] Specifically, if the set temperature of the refrigerant or the temperature measured by the temperature sensor 23 is above the boiling point of the refrigerant, the on / off control valve 16 is closed, thereby pressurizing the area within the path from the wafer mounting stage 24 to the intake 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 via the pressurization path 30. In addition, the driving rotation speed of the internal circulation pump 11 is increased based on the measurement result of the pressure sensor 26 installed in the external circulation path C1, 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, thereby suppressing cavitation of the refrigerant.

[0066] On the other hand, if the set temperature of the refrigerant or the temperature measured by the temperature sensor 23 is below the boiling point of the refrigerant, the on / off control valve 16 is opened, allowing the refrigerant flowing through the internal circulation path C1 to flow into the refrigerant tank 17 via the path 25 where the on / off control valve 16 is located, thus preventing pressurization by the pushing pressure of the internal circulation pump 11. As a result, a larger pressure difference is obtained between the inlet and outlet of the refrigerant flow path in the wafer mounting stage 24, which increases the flow rate of the refrigerant flowing through the refrigerant flow path in the wafer mounting stage 24, thereby providing a greater cooling effect on the wafer mounting stage 24.

[0067] Furthermore, according to the chiller system 1 of this embodiment, based on the measurement results of the temperature sensor 23 provided in the external circulation path C1, the connection path 19 connecting the internal circulation path C1 and the external circulation path C2 is opened or closed by the three-way valve 14, thereby circulating the cold refrigerant flowing through the internal circulation path C1 within the internal circulation path C1 or flowing into the external circulation path C2. This makes it possible to control the temperature of the refrigerant flowing through the external circulation path C2 within a predetermined range.

[0068] [Differentiation] In the above embodiment, a method for increasing the pushing pressure of the internal circulation pump 11 was shown in which 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, the embodiment is not limited to this, and for example, the throttling means 28 may be configured with an electrically driven valve (solenoid valve, electric valve, etc.) that can adjust 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] Furthermore, as a method for increasing the pushing pressure of the internal circulation pump 11, both the driving rotation speed of the internal circulation pump 11 based on the pressure measured by the pressure sensor 26 and the opening degree of the electrically driven valve constituting the throttling means 28 may be used in combination.

[0070] Although 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...Paths, 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 platform, 25...Return path 25, 26...Pressure sensor, 27...Second branch path, 28...Throttling means, 29...First branch path, 30...Pressurization path, 31...Branching 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 throttle 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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