Temperature control method and plasma processing device

Abstract

The present invention provides a temperature control method and a plasma processing device. The temperature control method includes a switching process, an ignition process, a calculation process, a first control process, and a second control process. In the switching process, the heat medium supplied to the flow path inside the mounting table is switched from a heat medium at a first temperature supplied by a first temperature control unit when an etching process is performed to a heat medium at a second temperature supplied by a second temperature control unit when a cleaning process is performed. In the ignition process, the supply of cleaning gas is started and the plasma is ignited. In the slope calculation process, the slope of the temperature change of the heat medium is calculated based on the temperature of the heat medium on the outlet side of the flow path. In the first control process, the second temperature control unit is controlled until the temperature of the heat medium on the outlet side of the flow path is stabilized at a third temperature. In the second control process, the second temperature control unit is controlled so that the temperature of the heat medium on the outlet side of the flow path becomes a set value.

Description

Technical Field

[0001] The present disclosure relates to a temperature control method and a plasma processing apparatus. Background Art

[0002] Plasma etching is known to be performed on substrates such as semiconductor wafers in plasma processing equipment. During the etching process, reaction products sometimes adhere to the periphery of the substrate or the periphery of the mounting surface of a substrate-supporting table. Reaction products adhering to the periphery of the mounting surface (hereinafter referred to as deposits) can sometimes hinder adsorption between the mounting surface and the substrate. To address this issue, a method has been proposed for removing deposits by irradiating the mounting table with a plasma generated from a mixture of O2 gas and a fluorine-containing gas.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2011-054825 Summary of the Invention

[0006] Problems to be solved by the invention

[0007] The present disclosure provides a temperature control method and a plasma processing apparatus capable of shortening cleaning time.

[0008] Solutions for solving problems

[0009] A temperature control method according to one embodiment of the present disclosure includes a switching step, an ignition step, a calculation step, a first control step, and a second control step. In the switching step, a heat medium supplied to a flow path disposed within a mounting table, which is disposed within a processing vessel of a plasma processing apparatus and is used to mount a substrate, is switched from a heat medium at a first temperature to a heat medium at a second temperature. The first temperature is supplied by a first temperature control unit when etching the substrate, and the second temperature is supplied by a second temperature control unit when cleaning the substrate after removal from the processing vessel to remove reaction products adhered to an electrostatic chuck disposed above the mounting table. In the ignition step, a cleaning gas is started to be supplied to the processing vessel, and plasma is ignited. In the slope calculation step, a slope of a temperature change of the heat medium is calculated based on the temperature of the heat medium at the outlet of the flow path. In the first control step, the second temperature control unit is controlled until the temperature of the heat medium at the outlet of the flow path stabilizes at a third temperature lower than a preset set value. In the second control step, the second temperature control unit is controlled so that the temperature of the heat medium at the outlet of the flow path reaches the set value.

[0010] Effects of the Invention

[0011] According to the present disclosure, cleaning time can be shortened. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a schematic cross-sectional view showing an example of a plasma processing apparatus according to one embodiment of the present disclosure.

[0013] Figure 2 This is a diagram showing an example of a location where sediment is deposited.

[0014] Figure 3 This is a graph showing an example of the temperature dependence of the etching rate of an organic film.

[0015] Figure 4 This is a diagram showing an example of the operating temperature range of the heat medium.

[0016] Figure 5 This is a diagram showing an example of a temperature control device in this embodiment.

[0017] Figure 6 This is a diagram showing an example of a state in which the heat medium is supplied from the first temperature control unit.

[0018] Figure 7 This is a diagram showing an example of a state in which the heat medium is supplied from the second temperature control unit.

[0019] Figure 8 This is a diagram showing an example of a temperature control map when the temperature of the heat medium is equal to or lower than a set value in this embodiment.

[0020] Figure 9 This is a diagram showing an example of a temperature control map when the temperature of the heat medium exceeds a set value in this embodiment.

[0021] Figure 10 This is a flowchart showing an example of the temperature control process in this embodiment.

[0022] Figure 11 This is a flowchart showing an example of the slope calculation process in this embodiment.

[0023] Figure 12 This is a flowchart showing an example of the first control process in this embodiment.

[0024] Figure 13 This is a flowchart showing an example of the second control process in this embodiment.

[0025] Figure 14 It is a diagram showing an example of a temperature control device in a modified example.

[0026] Description of Reference Numerals

[0027] 1: Plasma processing device; 10: Device body; 11: Control device; 12: Processing container; 15: Flow path; 16a: Piping; 16b: Piping; 20, 20a: Temperature control device; 101, 102: Deposition (reaction product); 103: BSP (reaction product); 200, 200a: First switching unit; 2000: First supply valve; 2001: Second supply valve; 2002: Supply valve; 2010: First return valve; 2011: Second return valve; 2012: Return valve; 201, 201a: Second switching unit; 204: First bypass valve; 205: Second bypass valve; 206: First temperature control unit; 207: Second temperature control unit; ESC: Electrostatic chuck; LE: Lower electrode; PD: Supporting table; W: Wafer. DETAILED DESCRIPTION

[0028] Hereinafter, embodiments of the disclosed temperature control method and plasma processing apparatus will be described in detail with reference to the accompanying drawings.

[0029] When etching a stacked film of SiO and SiN (hereinafter referred to as an ON stacked film) formed on a substrate (hereinafter also referred to as a wafer), a cooled liquid heat medium is supplied to a flow path provided inside the stage to set the temperature of the wafer to an extremely low temperature, for example, about -40°C to -80°C, thereby achieving an improvement in the etching rate and the mask selectivity. In such etching, organic deposits (reaction products) such as CF-based polymers will adhere to the shoulder and edge ring of the electrostatic chuck provided on the mounting surface of the stage during the etching process. Therefore, in between etching processes of the substrate, WLDC (Wafer Less Dry Cleaning) is performed using O2 gas to remove the attached deposits. However, when the temperature of the wafer is set to an extremely low temperature, the amount of attached deposits increases, and the removal rate based on WLDC becomes very slow, so the time spent on WLDC becomes very long, resulting in poor production capacity. Therefore, it is proposed to increase the removal rate by setting the temperature of the stage to a high temperature when performing WLDC. However, when the temperature is too high, the heat medium flowing through the flow path inside the mounting table vaporizes from its liquid state, reducing heat transfer efficiency. Furthermore, the volume of the vaporized heat medium expands, causing pressure within the flow path to rise, thus posing a risk of device failure from a structural perspective. On the other hand, if there is a margin above the heat medium's vaporization temperature, the temperature will be correspondingly low, extending the WLDC time. Therefore, it is desirable to shorten cleaning time by controlling the temperature to the maximum possible temperature without vaporizing the heat medium.

[0030] [Structure of Plasma Processing Apparatus 1]

[0031] Figure 1 This is a schematic cross-sectional view showing an example of a plasma processing apparatus according to one embodiment of the present disclosure. Plasma processing apparatus 1 is, for example, a plasma etching apparatus equipped with parallel plate electrodes. Plasma processing apparatus 1 includes an apparatus body 10 and a control unit 11. Apparatus body 10 is constructed of a material such as aluminum and includes a processing vessel 12, which is, for example, substantially cylindrical. The inner wall surface of processing vessel 12 is anodized. Processing vessel 12 is securely grounded.

[0032] A substantially cylindrical support portion 14 made of an insulating material such as quartz is provided on the bottom of the processing chamber 12. The support portion 14 extends vertically from the bottom of the processing chamber 12 (eg, toward the upper electrode 30).

[0033] A loading table PD is provided within the processing container 12. The loading table PD is supported by a support portion 14. A wafer W is held on the upper surface of the loading table PD. Wafer W is an example of a temperature-controlled object. The loading table PD includes an electrostatic chuck ESC and a lower electrode LE. The lower electrode LE is made of a metal material such as aluminum and has a substantially disk-like shape. The electrostatic chuck ESC is disposed on the lower electrode LE. The lower electrode LE is an example of a heat exchange member that exchanges heat with the temperature-controlled object.

[0034] The electrostatic chuck ESC has a structure in which an electrode EL, which is a conductive film, is disposed between a pair of insulating layers or a pair of insulating sheets. Electrode EL is electrically connected to a DC power supply 17 via a switch SW. The electrostatic chuck ESC uses electrostatic force, such as Coulomb force, generated by the DC voltage supplied from the DC power supply 17 to hold a wafer W on the upper surface of the electrostatic chuck ESC. This allows the electrostatic chuck ESC to hold the wafer W.

[0035] A heat transfer gas, such as He gas, is supplied to the electrostatic chuck ESC via a pipe 19. The heat transfer gas supplied via the pipe 19 is supplied between the electrostatic chuck ESC and the wafer W. By adjusting the pressure of the heat transfer gas supplied between the electrostatic chuck ESC and the wafer W, the thermal conductivity between the electrostatic chuck ESC and the wafer W can be adjusted.

[0036] Furthermore, a heater HT serving as a heating element is provided within the electrostatic chuck ESC. The heater HT is connected to a heater power supply HP. By supplying power from the heater power supply HP to the heater HT, the wafer W on the electrostatic chuck ESC can be heated via the electrostatic chuck ESC. The temperature of the wafer W placed on the electrostatic chuck ESC is adjusted by the lower electrode LE and the heater HT. Alternatively, the heater HT may be positioned between the electrostatic chuck ESC and the lower electrode LE.

[0037] An edge ring ER is arranged around the electrostatic chuck ESC to surround the edge of the wafer W and the electrostatic chuck ESC. The edge ring ER is sometimes also called a focus ring. The edge ring ER can improve the in-plane uniformity of processing on the wafer W. The edge ring ER is made of a material appropriately selected based on the material of the film being etched, for example, quartz.

[0038] A flow path 15 is formed inside the lower electrode LE, through which a heat medium such as Galden (registered trademark) flows as an insulating fluid. The heat medium is sometimes referred to as salt water. The flow path 15 is connected to a temperature control device 20 via pipes 16a and 16b. The temperature control device 20 controls the temperature of the heat medium flowing within the flow path 15 of the lower electrode LE. The heat medium, whose temperature is controlled by the temperature control device 20, is supplied to the flow path 15 of the lower electrode LE via pipe 16a. The heat medium flowing through the flow path 15 returns to the temperature control device 20 via pipe 16b.

[0039] The temperature control device 20 switches between a heat medium at a first temperature and a heat medium at a second temperature, and supplies the switched heat medium to the flow path 15 of the lower electrode LE. By switching between the heat medium at the first temperature and the heat medium at the second temperature and supplying the switched heat medium to the flow path 15 of the lower electrode LE, the temperature of the lower electrode LE is switched between the first temperature and the second temperature. The first temperature is, for example, a temperature below 0°C, and the second temperature is, for example, a temperature above room temperature. Hereinafter, the heat medium at the first temperature is referred to as the first heat medium, and the heat medium at the second temperature is referred to as the second heat medium. The first heat medium and the second heat medium are fluids of the same material but at different temperatures. The temperature control device 20 and the control device 11 are examples of heat medium control devices.

[0040] The lower surface of the lower electrode LE is electrically connected to a power supply tube 69 for supplying high frequency power to the lower electrode LE. The power supply tube 69 is made of metal. Figure 1 Although not shown in the figure, lift pins and their driving mechanism for transferring the wafer W on the electrostatic chuck ESC are arranged in the space between the lower electrode LE and the bottom of the processing container 12.

[0041] The power supply tube 69 is connected to the first high-frequency power supply 64 via a matching device 68. The first high-frequency power supply 64 generates high-frequency power, or high-frequency bias power, for attracting ions toward the wafer W. For example, the high-frequency bias power generates a frequency of 400 kHz to 40.68 MHz, or in one example, a frequency of 13.56 MHz. The matching device 68 is a circuit for matching the output impedance of the first high-frequency power supply 64 with the input impedance of the load (lower electrode LE). The high-frequency bias power generated by the first high-frequency power supply 64 is supplied to the lower electrode LE via the matching device 68 and the power supply tube 69.

[0042] An upper electrode 30 is provided above and facing the mounting table PD. The lower electrode LE and upper electrode 30 are arranged substantially parallel to each other. Plasma is generated in the space between the upper electrode 30 and the lower electrode LE, and the generated plasma performs plasma processing such as etching on the wafer W held on the upper surface of the electrostatic chuck ESC. The space between the upper electrode 30 and the lower electrode LE is referred to as the processing space PS.

[0043] The upper electrode 30 is supported on the upper portion of the processing chamber 12 via an insulating shielding member 32 made of, for example, quartz. The upper electrode 30 includes an electrode plate 34 and an electrode support 36. The lower surface of the electrode plate 34 faces the processing space PS. A plurality of gas ejection ports 34a are formed in the electrode plate 34. The electrode plate 34 is made of, for example, a material containing silicon.

[0044] The electrode support 36 is made of a conductive material such as aluminum, and supports the electrode plate 34 from above in a detachable manner. The electrode support 36 can have a water-cooling structure (not shown). A diffusion chamber 36a is formed inside the electrode support 36. A plurality of gas flow ports 36b extend downward (toward the mounting table PD) from the diffusion chamber 36a and are connected to the gas outlet 34a of the electrode plate 34. A gas inlet 36c for guiding the processing gas into the diffusion chamber 36a is provided on the electrode support 36, and the gas inlet 36c is connected to the pipe 38.

[0045] Piping 38 is connected to a gas source assembly 40 via a valve assembly 42 and a flow controller assembly 44. Gas source assembly 40 includes multiple gas sources. Valve assembly 42 includes multiple valves, and flow controller assembly 44 includes multiple flow controllers such as mass flow controllers. Each gas source in gas source assembly 40 is connected to piping 38 via a corresponding valve in valve assembly 42 and a corresponding flow controller in flow controller assembly 44.

[0046] Thus, the apparatus body 10 can supply processing gas from one or more gas sources selected from the gas source group 40 at individually adjusted flow rates to the diffusion chamber 36a within the electrode support 36. The processing gas supplied to the diffusion chamber 36a diffuses within the diffusion chamber 36a and is supplied in a spray-like manner into the processing space PS through the gas flow ports 36b and the gas ejection ports 34a.

[0047] The electrode support 36 is connected to the second high-frequency power supply 62 via a matching box 66. The second high-frequency power supply 62 is a power supply that generates high-frequency power for generating plasma, for example, high-frequency power with a frequency of 27 MHz to 100 MHz, and in one example, high-frequency power with a frequency of 60 MHz. The matching box 66 is a circuit for matching the output impedance of the second high-frequency power supply 62 with the input impedance of the load (upper electrode 30). The high-frequency power generated by the second high-frequency power supply 62 is supplied to the upper electrode 30 via the matching box 66. The second high-frequency power supply 62 may also be connected to the lower electrode LE via the matching box 66.

[0048] Sediment shields 46 are detachably mounted on the inner wall of the processing container 12 and the outer surface of the support portion 14. Sediment shields 46 are made of, for example, aluminum coated with Y2O3, quartz, or the like. Sediment shields 46 prevent etching byproducts (sediments) from adhering to the processing container 12 and the support portion 14.

[0049] An exhaust plate 48, made of aluminum or the like coated with Y2O3, quartz, or the like, is installed between the outer wall of the support portion 14 and the inner wall of the processing container 12, and on the bottom side of the processing container 12 (the side where the support portion 14 is installed). An exhaust port 12e is provided below the exhaust plate 48. The exhaust port 12e is connected to an exhaust device 50 via an exhaust pipe 52.

[0050] The exhaust device 50 includes a vacuum pump such as a turbomolecular pump and can reduce the pressure in the processing container 12 to a desired vacuum level. An opening 12g for loading and unloading wafers W is provided on the side wall of the processing container 12 and can be opened and closed by a gate valve 54 .

[0051] The control device 11 includes a processor, memory, and an input / output interface. The memory stores programs executed by the processor and recipes including conditions for each process. The processor executes the programs read from the memory and controls the various components of the apparatus body 10 via the input / output interface based on the recipes stored in the memory, thereby performing predetermined processes such as etching on the wafer W. The control device 11 is an example of a control unit.

[0052] [Sediment attachment site]

[0053] Here, use Figure 2 To illustrate where the sediment is attached. Figure 2 This is a diagram showing an example of where sediment is deposited. Figure 2 As shown, when wafer W is processed using plasma P while being held on the upper surface of the electrostatic chuck ESC, deposits 101 adhere to the shoulder of the electrostatic chuck ESC, near the boundary between the electrostatic chuck ESC and the edge ring ER. Furthermore, between the outer periphery of wafer W and the edge ring ER, deposits 102 adhere to the upper surface of the edge ring ER, and backside polymer (BSP) 103 adheres to the backside of the outer periphery of wafer W. The lower the temperature or the longer the plasma treatment time on wafer W, the greater the amount of deposits 101, 102, and BSP 103. When multiple wafers W are continuously plasma-treated, BSP 103 is removed along with the processed wafers W, but deposits 101 and 102 continue to adhere, further increasing the amount of deposits. When the deposits 101 and 102 increase, the deposits 101 and 102 may interfere with the next wafer W being transferred, or the deposits 101 and 102 may peel off and be placed on the upper surface of the electrostatic chuck ESC, thereby causing poor suction of the wafer W. In the following description, the deposits 101 and 102 may be collectively referred to as shoulder deposits.

[0054] [Temperature dependence of removal rate]

[0055] Next, use Figure 3 To illustrate the temperature dependence of the deposit removal rate. Figure 3 This is a graph showing an example of the temperature dependence of the etching rate of an organic film. Figure 3 FIG. 1 shows the temperature dependence of the etching rate of the organic film corresponding to the removal rate of the deposit when an organic film (photoresist) is used instead of the waste deposit. Figure 3 As shown in the graph 110, the relationship between the etching rate of the organic film and the temperature is that the higher the temperature, the higher the etching rate. Accordingly, it can also be said that in the extremely low temperature region 111 where the etching of the ON stacked film is performed, the removal rate of the shoulder deposits is very low, and a considerable amount of time is required to remove the shoulder deposits. Therefore, by repeating the low-temperature etching step and the high-temperature WLDC step, the time taken to remove the shoulder deposits can be shortened, thereby improving production capacity. In this case, the temperature is greatly adjusted between the low-temperature step and the high-temperature step. In addition, in the following description, such temperature adjustment is also referred to as inter-step temperature adjustment. Alternatively, after the low-temperature etching step, the low-temperature cleaning step consisting of a combination of low-temperature WWDC (Wafer With Dry Cleaning: wafer dry cleaning) and low-temperature WLDC performed using a wafer dummy is repeated multiple times, and then the high-temperature WLDC step is performed.

[0056] In inter-step temperature control, since the temperature range to be adjusted is wide, it is necessary to consider the operating temperature range of the heat medium. Figure 4 This is a diagram showing an example of the operating temperature range of the heat medium. Figure 4 Graph 112 shows the recommended operating temperature ranges for various heat media H1 to H5. As shown in Graph 112, heat media H5, which can be used in the extremely low-temperature range of -80°C to -40°C, also has a low vaporization temperature. To maximize the performance of low-temperature etching, it is preferable to use a heat media that prioritizes low temperatures. Therefore, control is required to prevent vaporization during temperature adjustment to the high-temperature side, while also maximizing the removal rate of shoulder deposits. The temperature control device 20 that performs this temperature control will now be described in detail.

[0057] [Structure of Temperature Control Device 20]

[0058] Figure 5 1 is a diagram showing an example of a temperature control device in this embodiment. The temperature control device 20 includes a first switching unit 200 , a second switching unit 201 , a first bypass valve 204 , a second bypass valve 205 , a first temperature control unit 206 , and a second temperature control unit 207 .

[0059] The first temperature control unit 206 is connected to the pipe 16a via the pipe 223 and the pipe 222. In addition, the first temperature control unit 206 is connected to the pipe 16b via the pipe 221 and the pipe 220. In this embodiment, the first temperature control unit 206 controls the temperature of the first heat medium on the low temperature side. The first temperature control unit 206 supplies the temperature-controlled first heat medium to the flow path 15 of the lower electrode LE via the pipe 223, the pipe 222, and the pipe 16a. Moreover, the heat medium supplied to the flow path 15 of the lower electrode LE returns to the first temperature control unit 206 via the pipe 16b, the pipe 220, and the pipe 221. The pipe consisting of the pipe 223, the pipe 222, and the pipe 16a is an example of a supply pipe or a first supply pipe. In addition, the pipe consisting of the pipe 16b, the pipe 220, and the pipe 221 is an example of a return pipe or a first return pipe.

[0060] The second temperature control unit 207 is connected to the pipe 16a and the pipe 222 at connection point A via the pipe 226 and the pipe 225. Furthermore, the second temperature control unit 207 is connected to the pipe 16b and the pipe 220 at connection point B via the pipe 228 and the pipe 227. In this embodiment, the second temperature control unit 207 controls the temperature of the second heat medium on the high-temperature side. The second temperature control unit 207 supplies the temperature-controlled second heat medium to the flow path 15 of the lower electrode LE via the pipe 226, the pipe 225, and the pipe 16a. Furthermore, the heat medium supplied to the flow path 15 of the lower electrode LE returns to the second temperature control unit 207 via the pipe 16b, the pipe 227, and the pipe 228. The pipes formed by the pipe 226 and the pipe 225 are an example of the second supply pipe. Furthermore, the pipes formed by the pipe 227 and the pipe 228 are an example of the second return pipe.

[0061] The first temperature control unit 206 and the second temperature control unit 207 are connected by a pipe 208. The pipe 208 is used to adjust the liquid level of the tank storing the first heat medium in the first temperature control unit 206 and the liquid level of the tank storing the second heat medium in the second temperature control unit 207. This prevents leakage of the heat medium.

[0062] The first switching unit 200 is provided at the connection between the pipe 16a and the pipe 225 and the pipe 222, and switches the heat medium flowing in the flow path 15 of the lower electrode LE to the first heat medium or the second heat medium. The first switching unit 200 includes a first supply valve 2000 and a second supply valve 2001.

[0063] The second switching unit 201 is provided at the connection between the pipe 16b and the pipe 227 and the pipe 220, and switches the output destination of the heat medium flowing out of the flow path 15 of the lower electrode LE to the first temperature control unit 206 or the second temperature control unit 207. The second switching unit 201 includes a first return valve 2010 and a second return valve 2011. In this embodiment, the first supply valve 2000, the second supply valve 2001, the first return valve 2010, and the second return valve 2011 are all two-way valves.

[0064] A pipe 224 is provided between a connection point D between the pipes 220 and 221 and a connection point C between the pipes 222 and 223. The pipe 224 is an example of a bypass pipe. The first bypass valve 204 is provided on the pipe 224.

[0065] A pipe 229 is provided between a connection point F between the pipes 227 and 228 and a connection point E between the pipes 225 and 226. The pipe 229 is an example of a bypass pipe. The second bypass valve 205 is provided on the pipe 229.

[0066] A thermometer 210 for measuring the temperature on the inlet side of the flow path 15 is provided on the piping 16a within the temperature control device 20. Furthermore, a thermometer 211 for measuring the temperature on the outlet side of the flow path 15 is provided on the piping 16b within the temperature control device 20. The thermometers 210 and 211 may also be provided outside the temperature control device 20. For example, the thermometers 210 and 211 may be provided directly below the lower electrode LE, for example, at the connection between the piping 16a and the flow path 15 and at the connection between the flow path 15 and the piping 16b, or may be provided at a location intermediate between the lower electrode LE and the temperature control device 20.

[0067] The opening and closing of the first supply valve 2000 , the second supply valve 2001 , the first return valve 2010 , the second return valve 2011 , the first bypass valve 204 , and the second bypass valve 205 are controlled by the control device 11 .

[0068] [Operation of Temperature Control Device 20]

[0069] Figure 6 This is a diagram showing an example of a state in which the heat medium is supplied from the first temperature control unit. Figure 6 The state in which the first heat medium at the low temperature side is supplied to the flow path 15 from the first temperature control unit 206 during etching is shown. In the following drawings, various valves are indicated by white background when they are open, and by black background when they are closed.

[0070] like Figure 6 As shown, the first temperature control unit 206 is set at a flow rate Q L The first heat medium is supplied to the pipe 223. Since the first bypass valve 204 is closed, the first heat medium passes through the connection point C at a flow rate Q. L Flows to the pipe 222. Since the first supply valve 2000 is closed and the second supply valve 2001 is open, the first heat medium flows through the second supply valve 2001 and the connection point A at a flow rate Q. L The liquid flows into the pipe 16 a on the inlet side and is supplied to the flow path 15 in the lower electrode LE.

[0071] After flowing through the flow path 15, the first heat medium passes through the outlet pipe 16b at a flow rate Q L Flows to the connection point B. Since the first return valve 2010 is closed, the first heat medium flows from the pipe 16b through the connection point B and the second return valve 2011 at a flow rate Q L Flows to the pipe 220. Since the first bypass valve 204 is closed, the first heat medium passes through the connection point D at a flow rate Q L The heat medium flows to the pipe 221 and returns to the first temperature control unit 206. At this time, the temperature of the first heat medium is controlled based on the measurement value of the thermometer 210.

[0072] On the other hand, the second heat medium on the high temperature side supplied from the second temperature control unit 207 is supplied at a flow rate Q H is supplied to the pipe 226. Since the first supply valve 2000 and the first return valve 2010 are closed and the second bypass valve 205 is open, the second heat medium flows at a flow rate Q H The liquid flows through the pipe 226 , the connection point E, the pipe 229 , the second bypass valve 205 , the connection point F, and the pipe 228 , and returns to the second temperature control unit 207 .

[0073] Figure 7 This is a diagram showing an example of a state in which the heat medium is supplied from the second temperature control unit. Figure 7 The figure shows a state where the second heat medium on the high temperature side is supplied from the second temperature control unit 207 to the flow path 15 when the cleaning process (WLDC) is being performed.

[0074] like Figure 7 As shown, the second temperature control unit 207 is set at a flow rate Q H The second heat medium is supplied to the pipe 226. Since the second bypass valve 205 is closed, the second heat medium passes through the connection point E at a flow rate Q. H Flows to the pipe 225. Since the first supply valve 2000 is open and the second supply valve 2001 is closed, the second heat medium flows through the first supply valve 2000 and the connection point A at a flow rate Q. H The liquid flows into the pipe 16 a on the inlet side and is supplied to the flow path 15 in the lower electrode LE.

[0075] After flowing through the flow path 15, the second heat medium passes through the pipe 16b on the outlet side at a flow rate Q H Flows to the connection point B. Since the second return valve 2011 is closed, the second heat medium flows from the pipe 16b through the connection point B and the first return valve 2010 at a flow rate Q H Flows to pipe 227. Since the second bypass valve 205 is closed, the second heat medium passes through the connection point F at a flow rate Q H The heat medium flows to the pipe 228 and returns to the second temperature control unit 207. At this time, the temperature of the second heat medium is controlled based on the measurement value of the thermometer 211.

[0076] On the other hand, the first heat medium on the low temperature side supplied from the first temperature control unit 206 is supplied at a flow rate Q L is supplied to the pipe 223. Since the second supply valve 2001 and the second return valve 2011 are closed and the first bypass valve 204 is open, the first heat medium flows at a flow rate Q L The liquid flows through the pipe 223 , the connection point C, the first bypass valve 204 , the pipe 224 , the connection point D, and the pipe 221 , and returns to the first temperature control unit 206 .

[0077] [Switching of heat medium]

[0078] When the etching process is completed and the process shifts to WLDC, the control device 11 switches the heat medium supplied to the flow path 15 in the lower electrode LE from Figure 6 The status shown is switched to Figure 7 The state shown is maintained to quickly switch the temperature of the mounting table PD. Specifically, the control device 11 switches the first heat medium (on the low-temperature side) supplied by the first temperature control unit 206 to the second heat medium (on the high-temperature side) supplied by the second temperature control unit 207. In the following description, the temperature of the first heat medium (on the low-temperature side) is set to, for example, -50°C, and the temperature of the second heat medium (on the high-temperature side) is set to, for example, 50°C.

[0079] use Figure 8 and Figure 9 A transient state when switching the heat medium in this manner will be described. Figure 8 This is a diagram showing an example of a temperature control graph when the temperature of the heat medium is equal to or lower than a set value in this embodiment. Figure 9 This is a diagram showing an example of a temperature control curve diagram when the temperature of the heat medium in this embodiment exceeds the set value. Figure 8 The graph 120 and Figure 9 The graph 130 shown shows the measured value of the thermometer 211 on the outlet side of the flow path 15, that is, the return side temperature T r transition state.

[0080] The control device 11 performs different controls in the interval 121 of rapid temperature change, the interval 122 in which the temperature change is stabilized, and the interval 123 in which the temperature after stabilization is gradually increased to the set value, as shown in the graph 120. Similarly, the control device 11 performs different controls in the interval 131 of rapid temperature change, the interval 132 in which the temperature change is stabilized, and the interval 133 in which the temperature after stabilization is gradually increased to the set value, as shown in the graph 130.

[0081] The control device 11 performs the following control in the intervals 121 and 131. First, the control device 11 controls the valves of the temperature control device 20 to switch the heat medium supplied to the flow path 15 from the first heat medium on the first temperature control unit 206 side to the second heat medium on the second temperature control unit 207 side. At this time, the control device 11 can return the temperature T r The set temperature of the second temperature control unit 207 when it is stabilized at the set value T3 is reflected as the set temperature of the second temperature control unit 207 at the start time of the current intervals 121 and 131.

[0082] After waiting for a predetermined time, the control device 11 starts supplying the cleaning gas into the processing container 12 and ignites the plasma. In addition, O2 gas can be used as the cleaning gas. In the graphs 120 and 130, the ignition time of the plasma is t0, and the return side temperature at that time is T r Assume T0. T0 is -50°C, for example. In the lower electrode LE, the temperature rises due to the heat input from the plasma. In addition, the first heat medium in the flow path 15 is squeezed out by the second heat medium, so the temperature also rises due to the second heat medium. In addition, the return side temperature T r The control device 11 calculates the slope of the temperature change based on an arbitrary time between time t0 and t1. The arbitrary time can be, for example, the time from switching the heat medium to the time when a fixed time has passed, or the time from switching the heat medium to the time when the specified temperature is reached. In addition, the return side temperature T at time t1 is r Let T1 be T1. T1 can be set to 30°C to 40°C, for example.

[0083] The control device 11 determines whether the calculated slope of the temperature change is greater than or equal to the threshold value m1. If the control device 11 determines that the slope of the temperature change is greater than or equal to the threshold value m1 (that is, in the case of the graph 130), the control device 11 lowers the set temperature of the second temperature control unit 207. If the control device 11 determines that the slope of the temperature change is less than the threshold value m1 (that is, in the case of the graph 120), the control device 11 does not change the set temperature of the second temperature control unit 207. At time t1, the control device 11 switches to control in the intervals 122 and 132. Note that the threshold value m1 is determined in advance through experiments, etc., but may also be set to reflect the results of the previous temperature control process.

[0084] The control device 11 performs the following control in the intervals 122 and 132. The control device 11 determines the return side temperature T r Whether it exceeds the set value T3. In addition, the set value T3 is a temperature as high as possible lower than the vaporization temperature of the second heat medium, for example, a temperature such as the vaporization temperature T4-5°C. For example, when the vaporization temperature T4 is set to 55°C, the set value T3 can be set to 50°C. In addition, the set value T3 can be set to a temperature close to the vaporization temperature T4, for example, a value such as 54.5°C. At the return side temperature T r If the return side temperature T does not exceed the set value T3, the control device 11 determines that the return side temperature T r The control device 11 determines whether the return side temperature T r If the change m of is less than the threshold value m2, the temperature change of the second heat medium is considered to be stable, and the control is switched to the intervals 123 and 133. On the other hand, when the control device 11 determines that the return side temperature T rWhen the change m is greater than the threshold value m2, the return side temperature T r Determination of whether the set value T3 is exceeded. The threshold value m2 is a value obtained in advance through experiments or the like.

[0085] The control device 11 determines that the return side temperature T r When the set value T3 is exceeded (i.e., when the curve 130 is reached), the heat medium supplied to the flow path 15 is switched to the first temperature control unit 206. In addition, the control device 11 lowers the set temperature of the second temperature control unit 207. That is, the control device 11 controls the temperature of the heat medium supplied to the flow path 15 by combining the switching of the heat medium with a fast response speed and the change of the set temperature of the second temperature control unit 207 with a slow response speed. After waiting for a predetermined time, the control device 11 determines whether the return side temperature T r Is the return side temperature T4 or higher? r If the temperature is equal to or higher than the vaporization temperature T4, an error is notified and the temperature control process and the cleaning process are stopped.

[0086] The control device 11 determines that the return side temperature T r If the return side temperature is lower than the vaporization temperature T4, the return side temperature T r Is it lower than the set value T3? The control device 11 determines that the return side temperature T r When the temperature is higher than the set value T3, the temperature returns to the return side temperature T after waiting for a predetermined time. r The control device 11 determines whether the return side temperature T4 is above the vaporization temperature. r If the temperature is lower than the set value T3, the heat medium supplied to the flow path 15 is switched to the second heat medium on the second temperature control unit 207 side, and the return side temperature is returned to T r In addition, the control device 11 may also switch the heat medium supplied to the flow path 15 to the second heat medium on the second temperature control unit 207 side after a predetermined time, instead of determining whether the return side temperature T r Is it lower than the set value T3?

[0087] Here, the temperature change in the intervals 122 and 132 will be described. As shown in the graph 120, when the temperature of the second heat medium does not exceed the set value T3, the return side temperature T r The temperature T1 at time t1 is raised to the steady-state temperature T2 without overshoot. In this case, the steady-state temperature T2 is, for example, 45°C. On the other hand, as shown in the graph 130, when the temperature of the second heat medium exceeds the set value T3, the temperature T2 is raised from the time t1 at which the temperature exceeds the set value T3. AFrom the time t until the time when the value becomes less than the set value T3 B During the period, the heat medium is temporarily switched to the first heat medium at the low temperature side. Then, the return side temperature T r After falling below the steady-state temperature T2, it turns to rise again and gradually rises to the steady-state temperature T2. In this case, the steady-state temperature T2 is, for example, 49°C. That is, the return side temperature T r The time t2 at which the temperature T2 in the steady state is reached varies depending on the temperature of the second heat medium. Note that the temperature T2 in the steady state is an example of the third temperature.

[0088] The control device 11 performs the following control in the intervals 123 and 133. The control device 11 adjusts the set temperature of the second temperature control unit 207 so that the return side temperature T r The control device 11 waits for a predetermined time and then determines the return side temperature T r Is it stable at the set value T3? r If the set value T3 is not stabilized, the control device 11 continues to adjust the set temperature of the second temperature control unit 207. r When the set value T3 is exceeded, the control device 11 can perform the same control as that in the intervals 122 and 132. r When the temperature on the return side is stabilized at the set value T3, the control device 11 sets the return side temperature T r The set value T3 is maintained until WLDC is completed. WLDC ends when the time for shoulder deposit removal, estimated from the shoulder deposit removal rate at the set value T3, has passed, or when the EPD (End-Point Detector) determines that shoulder deposit removal is complete.

[0089] [Temperature control method]

[0090] Next, the temperature control method according to this embodiment will be described. Figure 10 This is a flowchart showing an example of the temperature control process in this embodiment.

[0091] The control device 11 first executes a slope calculation process of calculating the slope of the temperature change when the heat medium is switched from the low temperature side to the high temperature side (step S1 ).

[0092] Here, use Figure 11 The slope calculation process will be described. Figure 11 This is a flowchart showing an example of the slope calculation process in this embodiment.

[0093] The controller 11 controls the valves of the temperature control device 20 to switch the heat medium supplied to the flow path 15 to the second heat medium on the second temperature control unit 207 side (step S11). At this time, the controller 11 switches the temperature-related input value from the value measured by the thermometer 210 to the value measured by the thermometer 211. The controller 11 waits for a predetermined time (step S12), starts supplying the cleaning gas into the processing container 12, and ignites the plasma (step S13). The controller 11 calculates the slope of the temperature change based on an arbitrary time between time t0 and time t1 (step S14).

[0094] The control device 11 determines whether the calculated slope of the temperature change is greater than or equal to the threshold value m1 (step S15). If the control device 11 determines that the slope of the temperature change is greater than or equal to the threshold value m1 (step S15: "Yes"), it lowers the set temperature of the second temperature control unit 207 (step S16), terminates the slope calculation process, and returns to the temperature control process. If the control device 11 determines that the slope of the temperature change is less than the threshold value m1 (step S15: "No"), it does not change the set temperature of the second temperature control unit 207, terminates the slope calculation process, and returns to the temperature control process. Thus, the control device 11 can calculate the slope of the temperature change.

[0095] Next, the control device 11 executes a first control process that performs control until the temperature change of the second heat medium stabilizes (step S2 ).

[0096] Here, use Figure 12 The first control process will be described. Figure 12 This is a flowchart showing an example of the first control process in this embodiment.

[0097] The control device 11 determines the return side temperature T r Whether it exceeds the set value T3 (step S21). r If the return side temperature T does not exceed the set value T3 (step S21: No), the control device 11 determines whether the return side temperature T r The control device 11 determines whether the change m of the return side temperature T is greater than the threshold value m2 (step S22). r If the change m is less than the threshold value m2 (step S22: No), it is considered that the return side temperature T r The first control process is terminated and the temperature control process is returned to the stable state temperature T2. On the other hand, the control device 11 determines that the return side temperature T r When the amount of change m is greater than or equal to the threshold value m2 (step S22: Yes), the process returns to step S21.

[0098] The control device 11 determines that the return side temperature T rIf the set value T3 is exceeded (step S21: Yes), the first heat medium on the first temperature control unit 206 side is switched (step S23). In addition, the control device 11 lowers the set temperature of the second temperature control unit 207 (step S24). The control device 11 waits for a predetermined time (step S25) and determines the return side temperature T r Is the return side temperature T4 or higher (step S26)? r If the temperature is equal to or higher than the vaporization temperature T4 (step S26: YES), an error is notified and the temperature control process and WLDC are stopped.

[0099] The control device 11 determines that the return side temperature T r If the return side temperature is lower than the vaporization temperature T4 (step S26: No), the return side temperature T r Is it less than the set value T3 (step S27)? The control device 11 determines that the return side temperature T r If the return side temperature T is greater than or equal to the set value T3 (step S27: No), the process returns to step S25. r If the return side temperature T is less than the set value T3 (step S27: Yes), the second heat medium on the second temperature control unit 207 side is switched (step S28), and the process returns to step S21. r Stablize.

[0100] When the first control process is completed, the control device 11 executes a second control process of gradually increasing the stabilized temperature to a set value (step S3 ).

[0101] Here, use Figure 13 The second control process will be described. Figure 13 This is a flowchart showing an example of the second control process in this embodiment.

[0102] The control device 11 adjusts the set temperature of the second temperature control unit 207 so that the return side temperature T r The control device 11 waits for a predetermined time (step S32) and determines the return side temperature T r Is it stable at the set value T3 (step S33). r If the return side temperature T is not stabilized at the set value T3 (step S33: No), the control device 11 returns to step S31. r When the temperature stabilizes at the set value T3 (step S33: YES), the control device 11 ends the second control process, returns to the temperature control process, and ends the temperature control process. rThe temperature stabilizes at the set value T3. Specifically, when transitioning from low-temperature etching to WLDC, control is performed to maximize the temperature without vaporizing the heat medium. This increases the removal rate of shoulder deposits and shortens the cleaning time. Furthermore, poor wafer adsorption due to shoulder deposits can be suppressed, enabling stable operation of the plasma processing apparatus 1. Furthermore, since cleaning time can be shortened, wafer productivity can be improved. Furthermore, differences in cleaning time between apparatuses due to piping length can be eliminated.

[0103] [Modification]

[0104] In the above embodiment, the first switching unit 200 is implemented by the first supply valve 2000 and the second supply valve 2001, which are two-way valves, and the second switching unit 201 is implemented by the first return valve 2010 and the second return valve 2011, which are two-way valves. Alternatively, the first switching unit 200 and the second switching unit 201 may each be implemented by a three-way valve. Figure 14 1 is a diagram showing an example of a temperature control device in a modified example. Compared with the temperature control device 20 of the above embodiment, Figure 14 The illustrated temperature control device 20 a includes a first switching portion 200 a and a second switching portion 201 a instead of the first switching portion 200 and the second switching portion 201 .

[0105] The first switching unit 200a is implemented by a three-way valve, a supply valve 2002. The supply valve 2002 corresponds to the first supply valve 2000 and the second supply valve 2001 of the first switching unit 200. Similar to the first switching unit 200, the first switching unit 200a switches the heat medium flowing in the flow path 15 of the lower electrode LE between the first heat medium and the second heat medium.

[0106] The second switching unit 201a is implemented by a return valve 2012, which is a three-way valve. The return valve 2012 corresponds to the first return valve 2010 and the second return valve 2011 of the second switching unit 201. Similar to the second switching unit 201, the second switching unit 201a switches the output destination of the heat medium flowing out of the flow path 15 of the lower electrode LE to the first temperature control unit 206 or the second temperature control unit 207. Using a three-way valve instead of a two-way valve in this manner also enables switching between the first and second heat media.

[0107] According to the present embodiment described above, the control device 11 switches the heat medium supplied to the flow path 15 provided inside the carrier PD from a heat medium at a first temperature to a heat medium at a second temperature. The carrier PD is arranged in the processing container 12 of the plasma processing device 1. Since the substrate is placed thereon, the heat medium at the first temperature is the heat medium supplied from the first temperature control unit 206 when etching the substrate, and the heat medium at the second temperature is the heat medium supplied from the second temperature control unit 207 when cleaning the reaction products attached to the electrostatic chuck ESC provided on the upper portion of the carrier PD after the substrate is unloaded from the processing container 12. In addition, the control device 11 starts supplying a cleaning gas into the processing container 12 and ignites the plasma. In addition, the control device 11 calculates the slope of the temperature change of the heat medium based on the temperature of the heat medium on the outlet side of the flow path 15. In addition, the control device 11 controls the second temperature control unit 207 until the temperature of the heat medium on the outlet side of the flow path 15 (T r ) is stabilized to a third temperature (T2) lower than a preset set value T3. In addition, the control device 11 controls the second temperature control unit 207 so that the temperature of the heat medium at the outlet side of the flow path 15 (T r ) becomes the set value T3. As a result, when switching from low-temperature etching to WLDC, control is performed so as to reach as high a temperature as possible without vaporizing the heat medium, thereby shortening the cleaning time.

[0108] According to the present embodiment, the temperature of the heat medium at the outlet side of the flow path 15 (T r ) exceeds the set value T3, the control device 11 switches the supply source of the heat medium to the flow path 15 to the first temperature control unit 206. As a result, the temperature of the heat medium (T r ) reaches the vaporization temperature T4.

[0109] Furthermore, according to this embodiment, after a predetermined time has passed, the control device 11 switches the supply source of the heat medium to the flow path 15 to the second temperature control unit. As a result, the temperature of the heat medium (T r ) drops significantly from the set value T3.

[0110] According to the present embodiment, the temperature of the heat medium at the outlet side of the flow path 15 (T r ) is lower than the set value T3, the control device 11 switches the supply source of the heat medium to the flow path 15 to the second temperature control unit 207. As a result, the temperature of the heat medium (T r ) drops significantly from the set value T3.

[0111] According to this embodiment, when the calculated slope of the temperature change is greater than the threshold, the control device 11 controls the second temperature control unit 207 to lower the second temperature. As a result, the temperature of the heat medium (T r ) reaches the vaporization temperature T4.

[0112] Furthermore, according to this embodiment, the control device 11 sets the set temperature of the second temperature control unit 207 to the second temperature (the temperature of the second heat medium) when the temperature of the heat medium at the outlet of the flow path 15 reaches the set value T3 in the previous second control step (second control process). As a result, the WLDC processing temperature can be reached and stabilized more quickly.

[0113] In addition, according to this embodiment, the setting value T3 is a temperature lower than the vaporization temperature T4 of the heat medium. As a result, the temperature of the heat medium (T r ) reaches the vaporization temperature T4.

[0114] In addition, in the above embodiment, O2 gas is used as the cleaning gas, but it is not limited to the disclosed technology. For example, the cleaning gas may also be other oxygen-containing gases such as CO gas, CO2 gas, and O3 gas.

[0115] In addition, in the above-mentioned embodiment, the deposits (reaction products) attached to the shoulder and edge ring of the electrostatic chuck are organic deposits such as CF-based polymers, but the disclosed technology is not limited to this. Depending on the type of the etched film on the substrate and the conditions used for etching, inorganic substances such as silicon and metals other than CF-based polymers are sometimes contained. In such a case, a halogen-containing gas, for example, may also be added to the O2 gas used as a cleaning gas. Regarding the halogen-containing gas, for example, fluorine-based gases such as CF4 gas and NF3 gas are listed. In addition, the halogen-containing gas may also be a chlorine-based gas such as Cl2 gas, or a bromine-based gas such as HBr gas. In addition, in the case where the deposits (reaction products) contain inorganic substances such as silicon and metals, the removal rate can also be increased by setting the temperature of the carrier during cleaning to a high temperature.

[0116] In the above embodiment, a capacitively coupled plasma (CCP) is used as an example of a plasma source, but the disclosed technology is not limited thereto. For example, an inductively coupled plasma (ICP), a microwave-excited surface wave plasma (SWP), an electron cyclotron resonance plasma (ECP), or a helicon excited plasma (HWP) may also be used as a plasma source.

[0117] In the above embodiment, a plasma etching apparatus is used as an example of the plasma processing apparatus 1. However, the disclosed technology is not limited thereto. The disclosed technology can also be applied to apparatuses other than etching apparatuses that use a temperature-controlled heat medium to control the temperature of a temperature-controlled object such as a wafer W, such as a film forming apparatus, a modifying apparatus, or a cleaning apparatus.

[0118] The embodiments disclosed herein are to be considered in all respects as illustrative and non-restrictive, and the embodiments described above may be omitted, replaced, or modified in various ways without departing from the scope of the appended claims and the spirit thereof.

Claims

1. A temperature control method comprising the following steps: a switching step of switching a heat medium supplied to a flow path provided inside a mounting table from a heat medium at a first temperature to a heat medium at a second temperature, the mounting table being disposed in a processing container of a plasma processing apparatus and configured to mount a substrate thereon, the heat medium at the first temperature being supplied by a first temperature control unit when performing an etching process on the substrate, and the heat medium at the second temperature being supplied by a second temperature control unit when performing a cleaning process to remove reaction products attached to an electrostatic chuck provided on an upper portion of the mounting table after the substrate is unloaded from the processing container; an ignition step of starting to supply a cleaning gas into the processing container and igniting the plasma; a slope calculation step of calculating a slope of a temperature change of the heat medium based on a temperature of the heat medium at an outlet side of the flow path; a first control step of controlling the second temperature control unit until the temperature of the heat medium at the outlet side of the flow path stabilizes at a third temperature lower than a preset set value, wherein the set value is a temperature lower than a vaporization temperature of the heat medium; as well as The second control step controls the second temperature control unit so that the temperature of the heat medium at the outlet side of the flow path becomes the set value.

2. The temperature control method according to claim 1, characterized in that: In the first control step, when the temperature of the heat medium at the outlet side of the flow path exceeds the set value, the supply source of the heat medium to the flow path is switched to the first temperature control unit.

3. The temperature control method according to claim 2, characterized in that: In the first control step, after a predetermined time has elapsed, the supply source of the heat medium to the flow path is switched to the second temperature control unit.

4. The temperature control method according to claim 2, characterized in that: In the first control step, when the temperature of the heat medium at the outlet side of the flow path is lower than the set value, the supply source of the heat medium to the flow path is switched to the second temperature control unit.

5. The temperature control method according to any one of claims 1 to 4, characterized in that: In the slope calculation step, when the calculated slope of the temperature change is equal to or greater than a threshold value, the second temperature control unit is controlled to lower the second temperature.

6. The temperature control method according to any one of claims 1 to 4, characterized in that: In the switching step, the set temperature of the second temperature control unit when the temperature of the heat medium at the outlet side of the flow path in the previous second control step reaches the set value is set to the second temperature.

7. A plasma processing apparatus comprising: Processing containers; a mounting table, disposed in the processing container and used for mounting a substrate; a first temperature control unit that supplies a heat medium at a first temperature to a flow path provided inside the mounting table; a second temperature control unit configured to supply the heat medium at a second temperature to the flow path; as well as Control Department, The control unit is configured to control the plasma processing apparatus so as to switch the heat medium supplied to the flow path from the heat medium at the first temperature to the heat medium at the second temperature, wherein the heat medium at the first temperature is the heat medium supplied when etching the substrate, and the heat medium at the second temperature is the heat medium supplied when cleaning the substrate after it is unloaded from the processing container to remove reaction products attached to an electrostatic chuck provided on an upper portion of the mounting table. The control unit is configured to control the plasma processing apparatus to start supplying the cleaning gas into the processing container and ignite the plasma. The control unit is configured to control the plasma processing apparatus so as to calculate a slope of a temperature change of the heat medium based on a temperature of the heat medium at an outlet side of the flow path. The control unit is configured to control the plasma processing apparatus to control the second temperature control unit until the temperature of the heat medium at the outlet side of the flow path stabilizes at a third temperature lower than a preset set value, wherein the set value is a temperature lower than a vaporization temperature of the heat medium. The control unit is configured to control the plasma processing apparatus to control the second temperature control unit so that the temperature of the heat medium at the outlet side of the flow path becomes the set value.

Images