Substrate processing apparatus

Abstract

To provide a technique for controlling the thermal resistance of a refrigerant.SOLUTION: The substrate processing apparatus includes a substrate processing chamber, a base, a circulator, and a bubble supplier. The base is disposed within the substrate processing chamber and configured to support a substrate placing unit on which a substrate is placed. The circulation unit is connected to the coolant flow path and circulates the coolant in the coolant flow path. The bubble supply unit supplies bubbles to the coolant in the coolant path.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a substrate processing apparatus. [Background technology]

[0002] Patent Document 1 listed below discloses a plasma processing apparatus comprising: a processing vessel defining a plasma processing space; a mounting table disposed within the processing vessel and on which a substrate to be processed is placed; a gas supply mechanism for introducing a processing gas used in a plasma reaction into the plasma processing space; a plasma generation mechanism for supplying electromagnetic energy for converting the processing gas introduced into the plasma processing space into plasma; a plurality of coolant flow paths formed inside the mounting table; a temperature adjustment unit for controlling the temperature of the coolant circulating through the plurality of coolant flow paths; check valves disposed in some of the plurality of coolant flow paths; and a reversing mechanism for reversing the flow direction of the coolant circulating through the plurality of coolant flow paths. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-11382 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides techniques for controlling the thermal resistance of a refrigerant. [Means for solving the problem]

[0005] A substrate processing apparatus according to one aspect of the present disclosure includes a substrate processing chamber, a base, a circulation unit, and an air bubble supply unit. The base is disposed in the substrate processing chamber and supports a substrate support unit on which a substrate is placed, and a coolant flow path is formed. The circulation unit is connected to the coolant flow path and circulates the coolant through the coolant flow path. The air bubble supply unit supplies air bubbles to the coolant in the coolant flow path.

[0006] According to another aspect of the present disclosure, a substrate processing apparatus includes a substrate processing chamber, a base, a circulation unit, and a controller. The base is disposed within the substrate processing chamber and supports a substrate placement unit on which a substrate is placed, and a coolant flow path is formed. The circulation unit is connected to the coolant flow path and circulates the coolant through the coolant flow path. The controller executes processes including the steps of: setting a heat transfer coefficient between a coolant in the coolant flow path and the coolant flow path to a first value when heating the substrate; setting the heat transfer coefficient between the coolant and the coolant flow path to a second value greater than the first value when processing the substrate; and setting the heat transfer coefficient between the coolant and the coolant flow path to a third value greater than both the first and second values ​​when cooling the substrate. [Effects of the Invention]

[0007] According to the present disclosure, the thermal resistance of the refrigerant can be controlled. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of a plasma processing system. [Figure 2] FIG. 2 is a diagram illustrating an example of the configuration of a capacitively coupled plasma processing apparatus. [Figure 3] FIG. 3 is a diagram illustrating an example of a configuration for adjusting the temperature of the main body according to the embodiment. [Figure 4A] FIG. 4A is a diagram illustrating an example of heat transfer in a main body portion according to an embodiment. [Figure 4B] FIG. 4B is a diagram illustrating an example of heat transfer in the main body portion according to the embodiment. [Figure 5] FIG. 5 is a diagram illustrating an example of the correlation between the Nusselt number and the Reynolds number. [Figure 6A] FIG. 6A is a diagram illustrating an example of the state of a refrigerant flowing through a flow path according to the embodiment. [Figure 6B] FIG. 6B is a diagram illustrating an example of the state of the refrigerant flowing through the flow path according to the embodiment. [Figure 6C] FIG. 6C is a diagram illustrating an example of the state of the refrigerant flowing through the flow path according to the embodiment. [Figure 7] FIG. 7 is a diagram illustrating an example of a flow of substrate processing according to an embodiment. [Figure 8] FIG. 8 is a flowchart showing an example of a control method according to the embodiment. [Figure 9A] FIG. 9A is a cross-sectional view showing an example of a schematic configuration of a bubble removal unit according to an embodiment. [Figure 9B] FIG. 9B is a cross-sectional view showing another example of the schematic configuration of the bubble removal unit according to the embodiment. [Figure 10] FIG. 10 is a diagram showing an example of the surface structure of the wall surface of the flow channel according to the embodiment. [Figure 11] FIG. 11 is a diagram illustrating another example of the configuration for adjusting the temperature of the main body according to the embodiment. [Figure 12A] FIG. 12A is a diagram showing an example of a riblet structure according to an embodiment. [Figure 12B] FIG. 12B is a diagram showing another example of a riblet structure according to the embodiment. [Figure 13A] FIG. 13A is a diagram illustrating the height of a convex portion according to an embodiment. [Figure 13B] FIG. 13B is a diagram illustrating the height of the convex portion according to the embodiment. [Figure 14A] FIG. 14A is a diagram showing an example of a change in the flow velocity of the refrigerant over time. [Figure 14B] FIG. 14B is a diagram showing an example of a thermal boundary layer formed in the flow channel in response to the change in the flow velocity over time shown in FIG. 14A. [Figure 15A] FIG. 15A is a diagram showing an example of a change in the flow velocity of the refrigerant over time. [Figure 15B] FIG. 15B is a diagram showing an example of a thermal boundary layer formed in the flow channel in response to the change in the flow velocity over time shown in FIG. 15A. [Figure 16] FIG. 16 is a diagram illustrating another example of a configuration for adjusting the temperature of the main body according to the embodiment. [Figure 17] FIG. 17 is a diagram illustrating the adjustment of the opening degree of a pipe by a valve according to the embodiment. [Figure 18]FIG. 18 is a diagram illustrating another example of the configuration for adjusting the temperature of the main body according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the substrate processing apparatus disclosed herein will be described in detail below with reference to the accompanying drawings. However, the substrate processing apparatus disclosed herein is not limited to the preferred embodiments.

[0010] A substrate processing apparatus includes a substrate support unit provided in a substrate processing chamber where substrate processing is performed. The substrate support unit is configured by joining an electrostatic chuck and a base. A substrate is placed on the electrostatic chuck. The electrostatic chuck electrostatically attracts the placed substrate.

[0011] The substrate support controls the temperature of the substrate. For example, the base is cooled by flowing a coolant through a flow path formed inside. The electrostatic chuck includes a heater and heats the substrate. The substrate support controls the temperature of the substrate by changing the temperature of the heater while cooling the substrate with the base. For example, when substrate processing is performed, power is supplied to the heater to generate heat and raise the temperature of the substrate to a predetermined processing temperature. Furthermore, when substrate processing is completed, the power supplied to the heater is turned off to cool the substrate.

[0012] By the way, if the substrate support part is configured with low thermal resistance, heat can be easily transferred and the heat removal capacity is increased. This allows the substrate processing apparatus to quickly cool the substrate when the power supply to the heater is turned off, thereby increasing production efficiency.

[0013] However, if the substrate support part is configured with a small thermal resistance, its heat dissipation capacity is high, so that when the substrate temperature is maintained at a predetermined processing temperature or when the substrate temperature is increased, the heater's heat output must be increased, resulting in increased power consumption by the heater, especially when the substrate temperature is increased.

[0014] The heat removal capacity of the substrate support can be changed by changing the thermal resistance of the coolant, so there is hope for a technology that can control the thermal resistance of the coolant.

[0015] [Embodiment] [Device configuration] An example of a substrate processing apparatus according to the present disclosure will be described. In the embodiment described below, the substrate processing apparatus according to the present disclosure is used as a plasma processing system in a system configuration, and plasma processing is performed as substrate processing.

[0016] FIG. 1 is a diagram illustrating an exemplary configuration of a plasma processing system. In one embodiment, the plasma processing system includes a plasma processing apparatus 1 and a control unit 2. The plasma processing system is an example of a substrate processing apparatus according to the present disclosure. The plasma processing apparatus 1 includes a plasma processing chamber 10, a substrate support 11, and a plasma generation unit 12. The plasma processing chamber 10 has a plasma processing space. The plasma processing chamber 10 also has at least one gas supply port for supplying at least one processing gas to the plasma processing space and at least one gas exhaust port for exhausting gas from the plasma processing space. The gas supply port is connected to a gas supply unit 20 (described later), and the gas exhaust port is connected to an exhaust system 40 (described later). The substrate support 11 is disposed in the plasma processing space and has a substrate support surface for supporting a substrate.

[0017] The plasma generating unit 12 is configured to generate plasma from at least one processing gas supplied into the plasma processing space. The plasma formed in the plasma processing space may be capacitively coupled plasma (CCP), inductively coupled plasma (ICP), electron-cyclotron-resonance plasma (ECR plasma), helicon wave plasma (HWP), or surface wave plasma (SWP). Various types of plasma generating units may be used, including alternating current (AC) plasma generating units and direct current (DC) plasma generating units. In one embodiment, the AC signal (AC power) used in the AC plasma generating unit has a frequency in the range of 100 kHz to 10 GHz. Therefore, the AC signal includes a radio frequency (RF) signal and a microwave signal. In one embodiment, the RF signal has a frequency in the range of 100 kHz to 150 MHz.

[0018] The control unit 2 processes computer-executable instructions that cause the plasma processing apparatus 1 to perform various processes described in this disclosure. The control unit 2 may be configured to control each element of the plasma processing apparatus 1 to perform various processes described herein. In one embodiment, part or all of the control unit 2 may be included in the plasma processing apparatus 1. The control unit 2 may include a processing unit 2a1, a storage unit 2a2, and a communication interface 2a3. The control unit 2 may be implemented by, for example, a computer 2a. The processing unit 2a1 may be configured to read a program from the storage unit 2a2 and execute the read program to perform various control operations. The program may be stored in the storage unit 2a2 in advance or may be acquired via a medium when needed. The acquired program is stored in the storage unit 2a2 and read from the storage unit 2a2 by the processing unit 2a1 for execution. The medium may be various storage media readable by the computer 2a or a communication line connected to the communication interface 2a3. The processing unit 2a1 may be a CPU (Central Processing Unit). The storage unit 2a2 may include a random access memory (RAM), a read only memory (ROM), a hard disk drive (HDD), a solid state drive (SSD), or a combination thereof. The communication interface 2a3 may communicate with the plasma processing apparatus 1 via a communication line such as a local area network (LAN).

[0019] The following describes a configuration example of a capacitively coupled plasma processing apparatus as an example of the plasma processing apparatus 1. Fig. 2 is a diagram for explaining a configuration example of a capacitively coupled plasma processing apparatus.

[0020] The capacitively coupled plasma processing apparatus 1 includes a plasma processing chamber 10, a gas supply 20, a power supply 30, and an exhaust system 40. The plasma processing apparatus 1 also includes a substrate support 11 and a gas inlet. The plasma processing chamber 10 is an example of a substrate processing chamber of the present disclosure. The gas inlet is configured to introduce at least one process gas into the plasma processing chamber 10. The gas inlet includes a showerhead 13. The substrate support 11 is disposed within the plasma processing chamber 10. The showerhead 13 is disposed above the substrate support 11. In one embodiment, the showerhead 13 forms at least a portion of the ceiling of the plasma processing chamber 10. The plasma processing chamber 10 has a plasma processing space 10s defined by the showerhead 13, a sidewall 10a of the plasma processing chamber 10, and the substrate support 11. The plasma processing chamber 10 is grounded. The showerhead 13 and the substrate support 11 are electrically insulated from the housing of the plasma processing chamber 10.

[0021] The substrate support 11 includes a main body 111 and a ring assembly 112. The main body 111 has a central region 111a for supporting a substrate W and an annular region 111b for supporting the ring assembly 112. A wafer is an example of a substrate W. The annular region 111b of the main body 111 surrounds the central region 111a of the main body 111 in a plan view. The substrate W is disposed on the central region 111a of the main body 111, and the ring assembly 112 is disposed on the annular region 111b of the main body 111 so as to surround the substrate W on the central region 111a of the main body 111. Therefore, the central region 111a is also called a substrate support surface for supporting the substrate W, and the annular region 111b is also called a ring support surface for supporting the ring assembly 112.

[0022] In one embodiment, the main body 111 includes a base 1110 and an electrostatic chuck 1111. The electrostatic chuck 1111 is an example of a substrate support portion of the present disclosure. The base 1110 includes a conductive member. The conductive member of the base 1110 can function as a lower electrode. The electrostatic chuck 1111 is disposed on the base 1110. The electrostatic chuck 1111 includes a ceramic member 1111a and an electrostatic electrode 1111b disposed within the ceramic member 1111a. The ceramic member 1111a has a central region 111a. In one embodiment, the ceramic member 1111a also has an annular region 111b. Note that the annular region 111b may also be provided by another member surrounding the electrostatic chuck 1111, such as an annular electrostatic chuck or an annular insulating member. In this case, the ring assembly 112 may be disposed on the annular electrostatic chuck or the annular insulating member, or may be disposed on both the electrostatic chuck 1111 and the annular insulating member. Furthermore, at least one RF / DC electrode coupled to an RF power supply 31 and / or a DC power supply 32, which will be described later, may be disposed within the ceramic member 1111a. In this case, the at least one RF / DC electrode functions as a lower electrode. When a bias RF signal and / or a DC signal, which will be described later, is supplied to the at least one RF / DC electrode, the RF / DC electrode is also called a bias electrode. Note that the conductive member of the base 1110 and the at least one RF / DC electrode may function as multiple lower electrodes. Alternatively, the electrostatic electrode 1111b may function as a lower electrode. Therefore, the substrate support 11 includes at least one lower electrode.

[0023] The ring assembly 112 includes one or more annular members. In one embodiment, the one or more annular members include one or more edge rings and at least one cover ring. The edge rings are formed of a conductive or insulating material, and the cover rings are formed of an insulating material.

[0024] The substrate support 11 may also include a temperature adjustment module configured to adjust at least one of the electrostatic chuck 1111, the ring assembly 112, and the substrate to a target temperature. The temperature adjustment module may include a heater, a heat transfer medium, a flow path 1110a, or a combination thereof. The flow path 1110a is an example of a coolant flow path of the present disclosure. A heat transfer fluid such as brine or a gas flows through the flow path 1110a. In one embodiment, the flow path 1110a is formed in the base 1110, and one or more heaters are disposed in the ceramic member 1111a of the electrostatic chuck 1111. The substrate support 11 may also include a heat transfer gas supply unit configured to supply a heat transfer gas to a gap between the back surface of the substrate W and the central region 111a.

[0025] The showerhead 13 is configured to introduce at least one processing gas from the gas supply unit 20 into the plasma processing space 10s. The showerhead 13 has at least one gas supply port 13a, at least one gas diffusion chamber 13b, and multiple gas inlets 13c. The processing gas supplied to the gas supply port 13a passes through the gas diffusion chamber 13b and is introduced into the plasma processing space 10s from the multiple gas inlets 13c. The showerhead 13 also includes at least one upper electrode. In addition to the showerhead 13, the gas introduction unit may also include one or more side gas injectors (SGIs) attached to one or more openings formed in the sidewall 10a.

[0026] The gas supply unit 20 may include at least one gas source 21 and at least one flow controller 22. In one embodiment, the gas supply unit 20 is configured to supply at least one process gas from a corresponding gas source 21 to the showerhead 13 via a corresponding flow controller 22. Each flow controller 22 may include, for example, a mass flow controller or a pressure-controlled flow controller. Additionally, the gas supply unit 20 may include at least one flow modulation device that modulates or pulses the flow rate of the at least one process gas.

[0027] The power supply 30 includes an RF power supply 31 coupled to the plasma processing chamber 10 via at least one impedance matching circuit. The RF power supply 31 is configured to supply at least one RF signal (RF power) to at least one lower electrode and / or at least one upper electrode. This generates a plasma from at least one processing gas supplied to the plasma processing space 10s. Therefore, the RF power supply 31 can function as at least a part of the plasma generation unit 12. Furthermore, by supplying a bias RF signal to the at least one lower electrode, a bias potential is generated on the substrate W, and ion components in the formed plasma can be attracted to the substrate W.

[0028] In one embodiment, the RF power supply 31 includes a first RF generating unit 31a and a second RF generating unit 31b. The first RF generating unit 31a is coupled to at least one lower electrode and / or at least one upper electrode via at least one impedance matching circuit and is configured to generate a source RF signal (source RF power) for plasma generation. In one embodiment, the source RF signal has a frequency in the range of 10 MHz to 150 MHz. In one embodiment, the first RF generating unit 31a may be configured to generate multiple source RF signals having different frequencies. The generated one or more source RF signals are supplied to at least one lower electrode and / or at least one upper electrode.

[0029] The second RF generating unit 31b is coupled to at least one lower electrode via at least one impedance matching circuit and configured to generate a bias RF signal (bias RF power). The frequency of the bias RF signal may be the same as or different from the frequency of the source RF signal. In one embodiment, the bias RF signal has a frequency lower than the frequency of the source RF signal. In one embodiment, the bias RF signal has a frequency in the range of 100 kHz to 60 MHz. In one embodiment, the second RF generating unit 31b may be configured to generate multiple bias RF signals having different frequencies. The generated one or more bias RF signals are supplied to at least one lower electrode. In various embodiments, at least one of the source RF signal and the bias RF signal may be pulsed.

[0030] The power supply 30 may also include a DC power supply 32 coupled to the plasma processing chamber 10. The DC power supply 32 includes a first DC generator 32a and a second DC generator 32b. In one embodiment, the first DC generator 32a is connected to at least one lower electrode and configured to generate a first DC signal. The generated first DC signal is applied to the at least one lower electrode. In one embodiment, the second DC generator 32b is connected to at least one upper electrode and configured to generate a second DC signal. The generated second DC signal is applied to the at least one upper electrode.

[0031] In various embodiments, the first and second DC signals may be pulsed. In this case, a sequence of voltage pulses is applied to at least one lower electrode and / or at least one upper electrode. The voltage pulses may have a rectangular, trapezoidal, triangular, or combination thereof. In one embodiment, a waveform generator for generating a sequence of voltage pulses from the DC signal is connected between the first DC generator 32a and at least one lower electrode. Thus, the first DC generator 32a and the waveform generator constitute a voltage pulse generator. When the second DC generator 32b and the waveform generator constitute a voltage pulse generator, the voltage pulse generator is connected to at least one upper electrode. The voltage pulses may have either positive or negative polarity. Furthermore, the sequence of voltage pulses may include one or more positive voltage pulses and one or more negative voltage pulses within one period. The first and second DC generating units 32a and 32b may be provided in addition to the RF power supply 31, or the first DC generating unit 32a may be provided instead of the second RF generating unit 31b.

[0032] The exhaust system 40 may be connected to, for example, a gas exhaust port 10e provided at the bottom of the plasma processing chamber 10. The exhaust system 40 may include a pressure regulating valve and a vacuum pump. The pressure regulating valve regulates the pressure in the plasma processing space 10s. The vacuum pump may include a turbomolecular pump, a dry pump, or a combination thereof.

[0033] Next, a configuration for adjusting the temperature of the main body 111 according to the embodiment will be described. Fig. 3 is a diagram showing an example of a configuration for adjusting the temperature of the main body 111 according to the embodiment. The main body 111 is formed by joining an electrostatic chuck 1111 and a base 1110.

[0034] The electrostatic chuck 1111 has a central region 111a on which a substrate W is placed. The central region 111a of the electrostatic chuck 1111 is divided into a plurality of areas. The electrostatic chuck 1111 has a heater HT provided in each area. Each heater HT is connected to a heater power supply 60. Each heater HT generates heat when power is supplied from the heater power supply 60.

[0035] The base 1110 is formed with a supply port 1110b and a discharge port 1110c. A flow path 1110a connecting the supply port 1110b and the discharge port 1110c is formed inside the base 1110. A pipe 113a is connected to the supply port 1110b. A pipe 113b is connected to the discharge port 1110c. The pipes 113a and 113b are connected to a chiller unit 114. The chiller unit 114 stores a refrigerant such as brine and supplies the stored refrigerant to the pipe 113a. The refrigerant supplied from the chiller unit 114 is supplied to the flow path 1110a via the pipe 113a, flows from one end to the other end of the flow path 1110a, and returns to the chiller unit 114 via the pipe 113b. The chiller unit 114 is configured to be able to change the temperature of the stored refrigerant. The pipes 113a and 113b and the chiller unit 114 are an example of a circulation unit of the present disclosure.

[0036] The chiller unit 114 changes the temperature of the coolant supplied to the pipe 113a in accordance with control from the control unit 2. The plasma processing apparatus 1 controls the temperature of the substrate W for each area divided into the central region 111a by changing the temperature of each heater HT while circulating the temperature-controlled coolant from the chiller unit 114 through the flow path 1110a to cool the base 1110.

[0037] The plasma processing apparatus 1 includes a bubble supply unit 70. The bubble supply unit 70 is connected to a pipe 113a via a pipe 71. The bubble supply unit 70 supplies bubbles to the pipe 71. The pipe 71 is provided with a valve 72. The valve 72 is configured to be openable and closable. The valve 72 is opened and closed under control of the control unit 2. When supplying bubbles, the valve 72 is opened under control of the control unit 2. The bubble supply unit 70 supplies bubbles to the refrigerant in the pipe 113a via the pipe 71. For example, the bubble supply unit 70 supplies microbubbles with a diameter of 100 μm or less as bubbles. The bubble supply unit 70 supplies bubbles with a void fraction of 1% or less. The void fraction is the volume fraction of the gas phase in a given volume of a gas-liquid two-phase flow. In this embodiment, the void fraction is the volume fraction of bubbles in the fluid flowing through the pipe 113a. For example, the bubble supplying unit 70 supplies microbubbles to the refrigerant in the pipe 113a with a void ratio of 1% or less and 0.1% or more.

[0038] Bubbles supplied to the refrigerant gradually disappear. Therefore, if bubbles are supplied to a position far from flow path 1110a of pipe 113a, the bubbles may not reach flow path 1110a. For this reason, pipe 71 is preferably connected to a position close to supply port 1110b of pipe 113a. However, microbubbles remain in the liquid for a long time. When supplied to the refrigerant, microbubbles circulate through pipe 113a, flow path 1110a, pipe 113b, and chiller unit 114. For this reason, when supplying microbubbles to the refrigerant, pipe 71 may be connected to supply port 1110b of pipe 113a at a position far from the supply port 1110b. Alternatively, pipe 71 may be connected to pipe 113b, and bubbles may be supplied to the refrigerant in pipe 113b.

[0039] Pipe 115 is connected to pipes 113a and 113b. Plasma processing apparatus 1 is configured so that a portion of the coolant flowing through pipe 113a can be made to flow to pipe 113b via pipe 115. Pipe 115 is provided with valve 116. Valve 116 is configured so that its opening is adjustable. The opening of valve 116 is changed under control of control unit 2. Even when the coolant is supplied to pipe 113a at a constant flow rate from chiller unit 114, changing the opening of valve 116 to change the flow rate of the coolant flowing through pipe 115 changes the flow rate of the coolant in flow path 1110a, and the flow velocity of the coolant changes.

[0040] Incidentally, if the main body 111 is configured to have a small thermal resistance in the vertical direction (the direction from the electrostatic chuck 1111 to the base 1110), heat is easily transferred to the refrigerant, and the heat removal capacity is improved. FIGS. 4A and 4B are diagrams illustrating an example of heat transfer in the main body 111 according to the embodiment. FIG. 4A illustrates a case in which the thermal resistance of the main body 111 in the vertical direction is large, for example, by configuring the electrostatic chuck 1111 and the base 1110 using materials with high thermal resistance. FIG. 4B illustrates a case in which the thermal resistance of the main body 111 in the vertical direction is small, for example, by configuring the electrostatic chuck 1111 and the base 1110 using materials with low thermal resistance. Also, in FIGS. 4A and 4B, arrows indicate the flow of heat.

[0041] If the main body 111 has a large thermal resistance in the vertical direction, as shown in FIG. 4A, heat is not easily transferred from the electrostatic chuck 1111 to the base 1110, and little heat is transferred to the refrigerant in the flow path 1110a, resulting in a low heat removal capacity of the refrigerant.

[0042] On the other hand, when the main body 111 has a small thermal resistance in the vertical direction, as shown in FIG. 4B, heat is easily transferred from the electrostatic chuck 1111 to the base 1110, and a large amount of heat is transferred to the refrigerant in the flow path 1110a, thereby increasing the heat removal capacity of the refrigerant.

[0043] However, when the thermal resistance of the main body 111 is small, the heat removal capacity is high, so that when the temperature of the substrate W is maintained at a predetermined processing temperature or when the temperature of the substrate W is increased, the amount of heat generated by the heater HT needs to be increased, which increases the power consumption of the heater HT. In particular, when the temperature of the substrate W is increased, the power consumption of the heater HT increases.

[0044] The heat removal capacity of the main body 111 can be changed by changing the thermal resistance of the refrigerant.

[0045] Here, the thermal resistance of the refrigerant will be explained. The thermal resistance R of the refrigerant can be calculated from the following formula (1) using the heat transfer coefficient h between the refrigerant in the flow path 1110a and the flow path 1110a.

[0046] R = 1 / h (1)

[0047] where: R is the thermal resistance of the refrigerant. h is the heat transfer coefficient between the refrigerant in the flow path 1110a and the flow path 1110a.

[0048] The heat transfer coefficient h between the refrigerant in the flow path 1110a and the flow path 1110a can be calculated from the following formula (2).

[0049] h = (Nu k) / d (2)

[0050] where: Nu is the Nusselt number. k is the thermal conductivity of the refrigerant. d is the hydraulic diameter of the flow channel 1110a.

[0051] The Nusselt number Nu is a dimensionless number that represents the ratio of heat conduction to heat transfer in a convecting fluid. The Nusselt number Nu is correlated to the Reynolds number Re. The Reynolds number is a dimensionless quantity defined as the ratio of the viscous force to the inertial force of a fluid.

[0052] The Reynolds number Re can be calculated from the following equation (3).

[0053] Re = (ρ·U·d) / μ (3)

[0054] where: Re is the Reynolds number. ρ is the density of the refrigerant. U is the flow velocity of the refrigerant. μ is the viscosity of the refrigerant.

[0055] The correlation between the Nusselt number Nu and the Reynolds number Re can be expressed as an equation based on the results of experiments and simulations. Furthermore, when microbubbles are supplied to the refrigerant in the flow path 1110a as in this embodiment, the correlation between the Nusselt number Nu and the Reynolds number Re changes depending on the void fraction of the microbubbles.

[0056] Fig. 5 is a diagram illustrating an example of the correlation between the Nusselt number Nu and the Reynolds number Re. Fig. 5 shows an example of the correlation between the Nusselt number Nu and the Reynolds number Re when the refrigerant is water and the void fraction α of the microbubbles contained in the water is 0%, 0.09%, 0.17%, and 0.25%.

[0057] When the Reynolds number Re is large, the correlation between the Nusselt number Nu and the Reynolds number Re tends to be the same regardless of the void fraction α. ​​On the other hand, when the Reynolds number Re is small, the correlation between the Nusselt number Nu and the Reynolds number Re changes depending on the void fraction α. ​​For example, as shown in Figure 5, when the Reynolds number Re is 15×10 -3 In the following cases, the larger the void fraction α, the smaller the Nusselt number Nu becomes relative to the Reynolds number Re.

[0058] For example, the Nusselt number Nu can be expressed as the following equation (4).

[0059] Nu = 0.0023 Re 0.8 ·Pr 0.3 (4)

[0060] where: Pr is the Prandtl number.

[0061] The Prandtl number Pr is a dimensionless number that represents the ratio of the dynamic viscosity of a fluid to the thermal diffusion coefficient. The Prandtl number Pr can be calculated using the following equation (5):

[0062] Pr = (μ Cp) / k (5)

[0063] where: Cp is the specific heat of the refrigerant.

[0064] The viscosity μ of the refrigerant, the specific heat Cp of the refrigerant, and the thermal conductivity k of the refrigerant are determined depending on the liquid used as the refrigerant, and therefore the Prandtl number Pr is determined depending on the liquid used as the refrigerant.

[0065] The thermal resistance R of the refrigerant changes depending on the heat transfer coefficient h, as shown in formula (1). The smaller the heat transfer coefficient h, the larger the thermal resistance R of the refrigerant.

[0066] As shown in equation (2), the heat transfer coefficient h varies depending on the Nusselt number Nu, the thermal conductivity k of the refrigerant, and the hydraulic diameter d of the flow path 1110a. The thermal conductivity k of the refrigerant is determined depending on the liquid used as the refrigerant. The hydraulic diameter d of the flow path 1110a is determined depending on the flow path 1110a. Therefore, the heat transfer coefficient h varies depending on the Nusselt number Nu.

[0067] As shown in equation (4), the Nusselt number Nu changes depending on the Reynolds number Re and the Prandtl number Pr. The Prandtl number Pr is determined depending on the liquid used as the refrigerant. Therefore, the Nusselt number Nu changes depending on the Reynolds number Re.

[0068] As shown in equation (3), the Reynolds number Re varies depending on the density ρ of the refrigerant, the flow velocity U of the refrigerant, the viscosity μ of the refrigerant, and the hydraulic diameter d of the flow path 1110a. The density ρ of the refrigerant and the viscosity μ of the refrigerant are determined depending on the liquid used as the refrigerant. The hydraulic diameter d of the flow path 1110a is determined depending on the flow path 1110a. Therefore, the Reynolds number Re varies depending on the flow velocity U of the refrigerant.

[0069] Here, the correlation between the Nusselt number Nu and the Reynolds number Re changes by changing the void fraction of the microbubbles contained in the refrigerant, as shown in Figure 5. For example, when the Reynolds number Re is 15 × 10 -3 In the following cases, the higher the void fraction, the smaller the Nusselt number Nu.

[0070] Therefore, the heat transfer coefficient h changes depending on the void fraction of the microbubbles and the flow velocity U of the refrigerant. Therefore, the thermal resistance R of the refrigerant changes depending on the void fraction of the microbubbles and the flow velocity U of the refrigerant.

[0071] 6A to 6C are diagrams illustrating an example of the state of the refrigerant flowing through the flow path 1110a according to the embodiment. When the refrigerant flows through the flow path 1110a, a thermal boundary layer is formed near the wall surface of the flow path 1110a. The thermal boundary layer is a region where the flow of the refrigerant is slower and the temperature of the refrigerant changes rapidly compared to near the center of the flow path 1110a. The slower the flow rate of the refrigerant, the thicker the thermal boundary layer formed. Furthermore, when microbubbles are supplied to the refrigerant, the higher the void fraction, the thicker the thermal boundary layer formed.

[0072] FIG. 6A shows the case where microbubbles are not supplied to the refrigerant (void fraction = 0%) and the flow rate of the refrigerant flowing through the flow path 1110a is 30 [L / min]. In FIG. 6A, a thermal boundary layer is formed up to line L1. FIG. 6B shows the case where microbubbles are not supplied to the refrigerant (void fraction = 0%) and the flow rate of the refrigerant flowing through the flow path 1110a is 3 [L / min]. In FIG. 6B, a thermal boundary layer is formed up to line L2. Note that FIG. 6B also shows line L1 from FIG. 6A to make it easier to compare the thickness of the thermal boundary layer. As shown by line L2 in FIG. 6B, by slowing down the flow of the refrigerant, the thermal boundary layer is formed thicker than line L1.

[0073] Fig. 6C shows the case where microbubbles are supplied to the refrigerant and the flow rate of the refrigerant flowing through the flow path 1110a is set to 3 [L / min]. In Fig. 6C, a thermal boundary layer is formed up to line L3. Note that Fig. 6C also shows line L1 in Fig. 6A and line L2 in Fig. 6B to make it easier to compare the thicknesses of the thermal boundary layer. As shown by line L3 in Fig. 6C, supplying microbubbles to the refrigerant causes the thermal boundary layer to be formed thicker than line L2.

[0074] The thicker the thermal boundary layer, the greater the thermal resistance R of the refrigerant. For example, the thermal resistance R of the refrigerant is greater in Figure 6B than in Figure 6A, and greater in Figure 6C than in Figure 6B.

[0075] The plasma processing apparatus 1 according to this embodiment controls the thermal resistance R of the coolant. For example, the plasma processing apparatus 1 supplies bubbles to the coolant in the pipe 113a using the bubble supply unit 70. For example, the control unit 2 controls the bubble supply unit 70 to supply microbubbles from the bubble supply unit 70 to the coolant in the pipe 113a with a void fraction of 1% or less and 0.1% or more. The plasma processing apparatus 1 also controls the flow rate U of the coolant flowing through the flow path 1110a. For example, when the heater HT generates heat, such as when maintaining or increasing the temperature of the substrate W, the control unit 2 controls the opening of the valve 116 to flow a portion of the coolant into the pipe 115, thereby controlling the flow rate U of the coolant flowing through the flow path 1110a.

[0076] Here, a brief description will be given of a procedure for performing plasma processing such as plasma etching on a substrate W using the plasma processing system according to the embodiment. The substrate W is loaded into the plasma processing chamber 10 through a loading / unloading port (not shown) by a transfer mechanism such as a transfer arm, and placed on the central region 111a of the substrate support 11.

[0077] The plasma processing apparatus 1 evacuates the plasma processing chamber 10 to a predetermined vacuum level using the exhaust system 40. The plasma processing apparatus 1 controls the temperature of the substrate W by changing the temperature of the heater HT while circulating a coolant from the chiller unit 114 through the flow path 1110a to cool the base 1110. The plasma processing apparatus 1 applies a voltage from the power supply 30 to the electrostatic electrode 1111b of the electrostatic chuck 1111 to electrostatically attract the substrate W. The plasma processing apparatus 1 supplies a processing gas from the gas supply unit 20 and introduces the processing gas into the plasma processing chamber 10 through the shower head 13. The plasma processing apparatus 1 then supplies at least one RF signal from the RF power supply 31 to generate plasma in the plasma processing space 10s, and performs plasma processing on the substrate W.

[0078] FIG. 7 is a diagram illustrating an example of a flow of substrate processing according to an embodiment. FIG. 7 shows, in (A) to (D), an example of a flow of performing plasma processing as substrate processing on a substrate W. FIG. 7(A) shows a state before plasma processing in which the substrate W is placed on the central region 111a of the substrate support part 11. FIG. 7(B) shows a state during plasma processing in which the substrate W is etched by plasma. FIG. 7(C) shows a state after plasma processing is completed. FIG. 7(D) shows a state after the substrate W has been unloaded after plasma processing is completed.

[0079] For example, the control unit 2 controls the chiller unit 114 to circulate the refrigerant, the temperature of which is controlled, from the chiller unit 114 through the flow path 1110a. The control unit 2 also controls the bubble supply unit 70 to supply microbubbles from the bubble supply unit 70 to the refrigerant in the pipe 113a with a void ratio of 1% or less and 0.1% or more. For example, the control unit 2 controls the bubble supply unit 70 to supply microbubbles from the bubble supply unit 70 to the refrigerant in the pipe 113a with a void ratio of 1%. As a result, microbubbles are mixed in with the refrigerant circulating through the flow path 1110a.

[0080] As shown in FIG. 7(A), when the substrate W is placed on the central region 111a of the substrate support 11, the control unit 2 controls the heater power supply 60 to supply power to each heater HT, causing each heater HT to generate heat, thereby raising the temperature of the substrate W to a predetermined processing temperature suitable for plasma processing.

[0081] 7(B), heat is input from the plasma to the substrate W. During plasma processing, the control unit 2 controls the power supplied from the heater power supply 60 to each heater HT to maintain the temperature of the substrate W at a predetermined processing temperature.

[0082] 7(C), when the plasma processing on the substrate W is completed, the control unit 2 turns off the power supplied from the heater power supply 60 to each heater HT to cool the substrate W. When the cooling of the substrate W is completed, the substrate W is carried out from the substrate support unit 11 as shown in FIG.

[0083] The control unit 2 controls the chiller unit 114 to supply the coolant from the chiller unit 114 to the pipe 113a at a constant flow rate, thereby circulating the coolant through the flow path 1110a. When performing plasma processing on the substrate W, the control unit 2 controls the opening of the valve 116 to change the flow velocity U of the coolant flowing through the flow path 1110a, thereby changing the Reynolds number Re and thereby controlling the thermal resistance R of the coolant.

[0084] For example, as shown in FIG. 7(A), the control unit 2 changes the flow velocity U of the coolant to control the thermal resistance R of the coolant to be high when the temperature of the substrate W is increased. For example, the control unit 2 changes the flow velocity U of the coolant when the temperature of the substrate W is increased, and sets the heat transfer coefficient h to a first value. For example, the control unit 2 changes the flow velocity U of the coolant when the temperature of the substrate W is increased, and sets the heat transfer coefficient h to a first value. 3 The flow rate U of the refrigerant is controlled so that the temperature is about the same as the temperature of the refrigerant.

[0085] In this way, by increasing the thermal resistance R of the coolant when the temperature of the substrate W is increased, the heat removal capacity of the main body 111 is reduced. This allows the plasma processing apparatus 1 to quickly increase the temperature of the substrate W when the temperature of the substrate W is increased. Furthermore, by reducing the heat removal capacity of the main body 111, the plasma processing apparatus 1 can reduce the amount of heat generated by the heater HT required to increase the temperature of the substrate W. This allows the plasma processing apparatus 1 to reduce the power consumption of the heater HT when the temperature of the substrate W is increased. Furthermore, the plasma processing apparatus 1 can reduce the Reynolds number Re to 2.0×10 while mixing microbubbles in the coolant. 3 By setting the temperature to about this level, the temperature boundary layer in the flow path 1110a becomes thicker, and the thermal resistance R of the refrigerant can be made higher.

[0086] As shown in Fig. 7(B), during plasma processing in which the substrate W is etched by plasma, the control unit 2 increases the flow velocity U of the coolant to control the thermal resistance R of the coolant to be lower than that during temperature increase. For example, during etching of the substrate W, the control unit 2 changes the flow velocity U of the coolant to set the heat transfer coefficient h to a second value greater than the first value. For example, during plasma processing, the control unit 2 increases the flow velocity U of the coolant to set the Reynolds number Re to, for example, 40.0 x 10 3 For example, if the flow rate U during the temperature rise shown in FIG. 7A is Ua, the control unit 2 controls the flow rate U during plasma processing to, for example, five times that during the temperature rise (=5Ua).

[0087] Here, when raising the temperature of the substrate W, it is preferable that the heat removal capacity of the main body 111 is low in order to quickly raise the temperature of the substrate W. On the other hand, during plasma processing, if the heat removal capacity of the main body 111 is excessively low, the temperature of the substrate W will rise due to heat input from the plasma, and the temperature of the substrate W will no longer be controllable by the heater HT.

[0088] Therefore, the control unit 2 controls the thermal resistance R of the coolant to such an extent that the heat input from the plasma can be removed by the main body 111 during plasma processing. As a result, the plasma processing apparatus 1 can remove the heat input from the plasma by the main body 111, and can control the temperature of the substrate W by the heater HT. On the other hand, when raising the temperature of the substrate W, the control unit 2 controls the thermal resistance R of the coolant to be so high that the heat input from the plasma during plasma processing cannot be removed by the main body 111. In other words, the control unit 2 controls the thermal resistance R of the coolant to be higher when raising the temperature of the substrate W than when performing plasma processing. As a result, the plasma processing apparatus 1 can quickly increase the temperature of the substrate W when raising the temperature of the substrate W.

[0089] 7(C), the control unit 2 changes the flow velocity U of the coolant when the temperature of the substrate W is being lowered, thereby controlling the thermal resistance R of the coolant to be lower than when the temperature is being raised and during plasma processing. For example, the control unit 2 changes the flow velocity U of the coolant when the temperature of the substrate W is being lowered, thereby setting it to a third value greater than the first value and the second value. For example, the control unit 2 changes the flow velocity U of the coolant when the temperature of the substrate W is being lowered, thereby setting the Reynolds number Re to, for example, 80.0×10 3 For example, the control unit 2 controls the flow rate U during the temperature drop of the substrate W to be 10 times (=10Ua) that during the temperature rise.

[0090] In this way, by making the thermal resistance R of the coolant lower when the temperature of the substrate W is decreasing than when the temperature is increasing and during plasma processing, the heat removal capacity of the main body 111 is increased compared to when the temperature is increasing and during plasma processing. This allows the plasma processing apparatus 1 to quickly cool the substrate W when the temperature of the substrate W is decreasing.

[0091] [Control method] Fig. 8 is a flowchart showing an example of a control method according to the embodiment. Fig. 8 shows a flow in which the control unit 2 controls the thermal resistance R of the coolant when performing plasma processing on a substrate W. Before the processing of Fig. 8 begins, the control unit 2 controls the chiller unit 114 to circulate the temperature-controlled coolant from the chiller unit 114 through the flow path 1110a. The control unit 2 also controls the bubble supply unit 70 to supply microbubbles from the bubble supply unit 70 to the coolant in the pipe 113a with a void ratio of 1% or less and 0.1% or more. The processing illustrated in Fig. 8 is performed when the substrate W is placed in the central region 111a of the substrate support unit 11 and plasma processing on the substrate W is started.

[0092] The control unit 2 determines whether the temperature of the substrate W is rising (step S10). If the temperature of the substrate W is rising (step S10: Yes), the control unit 2 controls the thermal resistance R of the coolant to be high (step S11). For example, the control unit 2 sets the heat transfer coefficient h to a first value by changing the flow velocity U of the coolant.

[0093] On the other hand, if the substrate W is not being heated (step S10: No), the control unit 2 determines whether plasma processing is currently being performed (step S12). If plasma processing is currently being performed (step S12: Yes), the control unit 2 controls the thermal resistance R of the coolant to be lower than that during temperature heating (step S13). For example, during etching of the substrate W, the control unit 2 changes the flow velocity U of the coolant to set the heat transfer coefficient h to a second value greater than the first value.

[0094] On the other hand, if the substrate W is not being cooled (step S12: No), the control unit 2 determines whether the substrate W is being cooled (step S14). If the substrate W is being cooled (step S14: Yes), the control unit 2 controls the thermal resistance R of the coolant to be lower than when the substrate W is being heated and when the substrate W is being processed (step S15). For example, when the substrate W is being cooled, the control unit 2 changes the flow rate U of the coolant to set it to a third value greater than the first and second values.

[0095] If the temperature of the substrate W is not decreasing (step S14: No), the control unit 2 determines whether or not the plasma processing on the substrate W is completed (step S16). If the plasma processing on the substrate W is completed (step S16: Yes), the processing ends.

[0096] On the other hand, if the plasma processing on the substrate W is not completed (step S16: No), the process proceeds to S10 described above.

[0097] In the above embodiment, the refrigerant is supplied from chiller unit 114 to pipe 113a at a constant flow rate, and the flow rate of the refrigerant flowing through flow path 1110a is changed by changing the opening of valve 116. However, this is not limited to this. For example, the flow rate of the refrigerant supplied from chiller unit 114 may be changed to change the flow rate of the refrigerant flowing through flow path 1110a.

[0098] In the above embodiment, microbubbles are constantly supplied from the bubble supply unit 70 to the coolant in the pipe 113a when plasma processing is performed on the substrate W. However, this is not limiting. The control unit 2 may control the bubble supply unit 70 so that bubbles are supplied to the coolant at least when the substrate W is heated. For example, the control unit 2 may control the bubble supply unit 70 or the valve 72 to supply microbubbles to the coolant when the temperature of the substrate W is rising as shown in FIG. 7(A) and during plasma processing as shown in FIG. 7(B), and stop the supply of microbubbles when the temperature of the substrate W is decreasing as shown in FIG. 7(C). The control unit 2 may also supply microbubbles from the bubble supply unit 70 to the coolant in the pipe 113a when the temperature of the substrate W is rising, and stop the supply of microbubbles to the coolant during plasma processing and when the temperature of the substrate W is decreasing.

[0099] In the above embodiment, the thermal resistance R of the refrigerant is controlled by changing the flow rate of the refrigerant flowing through the flow path 1110a while supplying microbubbles to the refrigerant. However, this is not limiting. The control unit 2 may control the thermal resistance R of the refrigerant by controlling the bubble supply unit 70 or the valve 72 to change whether or not microbubbles are supplied or the void fraction of the microbubbles.

[0100] Furthermore, in the above embodiment, an example has been described in which, when the temperature of the substrate W is rising, the control unit 2 controls the thermal resistance R of the coolant to be so high that the heat input from the plasma during plasma processing cannot be removed by the main body 111. However, this is not limited to this. When the temperature of the substrate W is rising, the control unit 2 may control the thermal resistance R of the coolant to such an extent that the heat input from the plasma can be removed by the main body 111. For example, the control unit 2 may control the thermal resistance R of the coolant to be the same when the temperature of the substrate W is rising and when plasma processing is performed.

[0101] In the above embodiment, a case where a coolant containing microbubbles is constantly circulated through the pipe 113a, the flow path 1110a, the pipe 113b, and the chiller unit 114 has been described as an example. However, this is not limiting. For example, the plasma processing apparatus 1 may include a bubble removal unit that removes microbubbles from the coolant. FIG. 9A is a cross-sectional view showing an example of a schematic configuration of the bubble removal unit 120 according to the embodiment. FIG. 9A shows a case where the bubble removal unit 120 that removes microbubbles from the coolant is provided in the pipe 113b. The bubble removal unit 120 includes a tank 121 and a dry pump 122. The tank 121 is provided in the pipe 113b and stores the coolant flowing through the pipe 113b. The dry pump 122 is connected to the tank 121 via the pipe 123. The pipe 123 is provided with a valve 123a. The valve 123a is configured to be openable and closable. The valve 123a is opened and closed under the control of the control unit 2. The valve 123a is opened under the control of the control unit 2 when removing microbubbles from the refrigerant. The dry pump 122 reduces the pressure inside the tank 121 through the pipe 123. As the pressure inside the tank 121 is reduced, the size of air bubbles mixed in the refrigerant stored in the tank 121 increases, and the air bubbles rise to the surface and collapse at the water surface. This allows the air bubble removal unit 120 to remove microbubbles from the refrigerant stored in the tank 121. FIG. 9B is a cross-sectional view showing another example of the schematic configuration of the air bubble removal unit 120 according to this embodiment. The air bubble removal unit 120 shown in FIG. 9B includes the tank 121 and a heater 124. The heater 124 is provided in the tank 121 and heats the refrigerant stored in the tank 121. As the refrigerant stored in the tank 121 is heated, the size of air bubbles mixed in the refrigerant increases, and the air bubbles rise to the surface and collapse at the water surface. This allows the bubble removing unit 120 to remove microbubbles from the refrigerant stored in the tank 121.

[0102] In the above embodiment, the thermal resistance R of the refrigerant is controlled by changing the heat transfer coefficient h between the refrigerant in the flow path 1110a and the flow path 1110a while supplying microbubbles to the refrigerant and changing the flow rate of the refrigerant flowing through the flow path 1110a. However, this is not limited to this. For example, the thermal resistance R of the refrigerant may be controlled by forming a surface structure with projections and depressions on the wall surface of the flow path 1110a and changing the flow rate of the refrigerant flowing through the flow path 1110a to change the heat transfer coefficient h between the refrigerant in the flow path 1110a and the flow path 1110a. FIG. 10 is a diagram showing an example of the surface structure of the wall surface of the flow path 1110a according to this embodiment. FIG. 10 shows a case where a riblet structure 1113 having multiple linear projections 1113a arranged in parallel is formed on the surface of the wall surface of the flow path 1110a. In FIG. 10, the arrows indicate the direction of refrigerant flow in the flow path 1110a. The linear projections 1113a are each formed in the direction of refrigerant flow. Although FIG. 10 illustrates a case where the riblet structure 1113 is formed on one wall surface of the flow path 1110a having a rectangular cross section, the riblet structure 1113 may be formed on all wall surfaces of the flow path 1110a. FIG. 11 illustrates another example of a configuration for adjusting the temperature of the main body 111 according to the embodiment. In FIG. 11, the riblet structure 1113 is formed on the wall surface of the flow path 1110a facing the electrostatic chuck 1111. FIG. 12A illustrates an example of the riblet structure 1113 according to the embodiment. FIG. 12A illustrates a case where the cross-sectional shape of the convex portions 1113a is triangular. The angle θ of the tip of the convex portions 1113a is preferably 60° or less. The height hi of the convex portions 1113a is preferably 300 μm or less. The spacing s between the convex portions 1113a is preferably equal to or greater than the height hi of the convex portions 1113a. FIG. 12B illustrates another example of the riblet structure 1113 according to the embodiment. 12B shows a case where the cross-sectional shape of the protrusions 1113a is rectangular. The height hi of the protrusions 1113a is preferably 300 μm or less. The distance s between the centers of the protrusions 1113a is preferably equal to or greater than the height hi of the protrusions 1113a. The width t of the protrusions 1113a is preferably less than the distance s between the centers of the protrusions 1113a.

[0103] When a refrigerant flows through the flow path 1110a, a thermal boundary layer is formed near the wall surface of the flow path 1110a. When the height hi of the convex portions 1113a is greater than the thickness of the thermal boundary layer, the riblet structure 1113 can reduce pressure loss (frictional resistance) by moving turbulent vortices near the wall surface away from the wall surface. Furthermore, when the height hi of the convex portions 1113a is greater than the thickness of the thermal boundary layer, the riblet structure 1113 can promote heat transfer with the refrigerant by expanding the heat transfer area. On the other hand, when the height hi of the convex portions 1113a is smaller than the thickness of the thermal boundary layer, the riblet structure 1113 does not function as a rough surface, and the Nusselt number Nu is equivalent to that when the wall surface is smooth. The thickness of the thermal boundary layer varies depending on the Reynolds number Re; it is thin when the Reynolds number Re is large and thick when the Reynolds number Re is small. The Reynolds number Re varies depending on the flow velocity U of the refrigerant, and becomes large when the flow velocity U is fast.

[0104] The height hi of the convex portion 1113a is preferably lower than the thickness of the thermal boundary layer formed near the wall surface of the flow path 1110a when the substrate W is heated, and higher than the thickness of the thermal boundary layer when the temperature of the substrate W is lowered. FIGS. 13A and 13B are diagrams illustrating the height hi of the convex portion 1113a according to an embodiment. FIG. 13A schematically illustrates the state of the flow path 1110a when the temperature of the substrate W is lowered, as shown in FIG. 7C, for example. In FIG. 13A, the flow rate of the coolant is high and the flow velocity U of the coolant is fast, so a thermal boundary layer is formed near the wall surface of the flow path 1110a up to line L4. FIG. 13B schematically illustrates the state of the flow path 1110a when the temperature of the substrate W is raised, as shown in FIG. 7A, for example. In FIG. 13B, the flow rate of the coolant is low and the flow velocity U of the coolant is slow, so a thermal boundary layer is formed near the wall surface of the flow path 1110a up to line L5. The protrusions 1113a are formed so that the height hi is lower than the thickness of the thermal boundary layer when the temperature of the substrate W is rising and higher than the thickness of the thermal boundary layer when the temperature of the substrate W is falling. As a result, when the temperature of the substrate W is rising, the riblet structure 1113 has the protrusions 1113a inside the thermal boundary layer, so that the riblet structure 1113 can maintain heat transfer performance with the refrigerant at the same level as when the wall surface is a smooth surface. Furthermore, when the temperature of the substrate W is falling, the tips of the protrusions 1113a of the riblet structure 1113 are outside the thermal boundary layer, so that the heat transfer performance with the refrigerant can be improved compared to when the wall surface is a smooth surface.

[0105] In the above embodiment, the thermal resistance R of the refrigerant is controlled by changing the flow rate of the refrigerant flowing through the flow path 1110a to change the heat transfer coefficient h between the refrigerant in the flow path 1110a and the flow path 1110a. However, this is not limited to this. For example, the flow velocity U of the refrigerant flowing through the flow path 1110a may be periodically changed over time to change the heat transfer coefficient h between the refrigerant in the flow path 1110a and the flow path 1110a, thereby controlling the thermal resistance R of the refrigerant.

[0106] FIG. 14A is a diagram showing an example of a change in the refrigerant flow velocity U over time. FIG. 14A shows a case where the refrigerant flow velocity U is constant at U1. FIG. 14B is a diagram showing an example of a thermal boundary layer formed in the flow path 1110a as the flow velocity U of FIG. 14A changes over time. In FIG. 14B, a thermal boundary layer is formed up to line L6 near the wall surface of the flow path 1110a. FIG. 15A is a diagram showing an example of a change in the refrigerant flow velocity U over time. FIG. 15A shows a case where the average of the refrigerant flow velocity U is set to U1 and the refrigerant flow velocity U is periodically changed over time. The frequency at which the refrigerant flow velocity U is periodically changed over time is 1 Hz or higher. FIG. 15B is a diagram showing an example of a thermal boundary layer formed in the flow path 1110a as the flow velocity U of FIG. 15A changes over time. In FIG. 15B, a thermal boundary layer is formed up to line L7 near the wall surface of the flow path 1110a. 15A, when the flow velocity U of the refrigerant is periodically changed over time, the vortex structure on the wall surface fluctuates in a complex manner, and the thermal boundary layer becomes thinner. This increases the heat transfer between the wall surface of the flow path 1110a and the refrigerant, and reduces the thermal resistance R of the refrigerant.

[0107] FIG. 16 is a diagram illustrating another example of a configuration for adjusting the temperature of the main body 111 according to the embodiment. In FIG. 16, a valve 117 is provided in the pipe 113a. The valve 117 is configured to have an adjustable opening. The opening of the valve 117 is changed under the control of the control unit 2. FIG. 17 is a diagram illustrating adjustment of the opening of the pipe 113a by the valve 117 according to the embodiment. The valve 117 is adjustable in opening by operating the valve element 117a to change the area S of the flow path through which the refrigerant can pass. For example, the control unit 2 controls the valve 117 to move the valve element 117a of the valve 117 up and down at a frequency of 1 Hz or more. This imparts pulsation to the flow of the refrigerant, causing the flow velocity U of the refrigerant flowing through the flow path 1110a to change over time at a frequency of 1 Hz or more. The heat transfer coefficient h between the refrigerant in the flow path 1110a and the flow path 1110a changes by periodically changing the opening of the valve 117 to periodically change the flow velocity U of the refrigerant flowing through the flow path 1110a. The heat transfer coefficient h changes depending on the frequency and amplitude at which the flow velocity U changes over time.

[0108] The control unit 2 controls the heat transfer coefficient h by periodically changing the opening of the valve 117 at a frequency of 1 Hz or more. For example, the control unit 2 controls the chiller unit 114 to circulate the coolant from the chiller unit 114 through the flow path 1110a at a constant flow rate. The control unit 2 controls the heat transfer coefficient h by changing at least one of the frequency at which the opening of the valve 117 is changed and the width of the change in the opening. For example, as shown in FIG. 7(A), the control unit 2 sets the heat transfer coefficient h to a first value when the temperature of the substrate W is rising. As shown in FIG. 7(B), the control unit 2 sets the heat transfer coefficient h to a second value greater than the first value when the temperature of the substrate W is decreasing. As shown in FIG. 7(C), the control unit 2 sets the heat transfer coefficient h to a third value greater than the first and second values ​​when the temperature of the substrate W is decreasing. This allows the plasma processing apparatus 1 to quickly increase the temperature of the substrate W when the temperature of the substrate W is rising. Furthermore, the plasma processing apparatus 1 can reduce the amount of heat generated by the heater HT required to raise the temperature of the substrate W by reducing the heat removal capacity of the main body 111. This allows the plasma processing apparatus 1 to reduce the power consumption of the heater HT when raising the temperature of the substrate W. Furthermore, the plasma processing apparatus 1 can quickly cool the substrate W when lowering the temperature of the substrate W.

[0109] In the above embodiment, the thermal resistance R of the refrigerant is controlled by changing the flow rate of the refrigerant flowing through the flow path 1110a to change the heat transfer coefficient h between the refrigerant in the flow path 1110a and the flow path 1110a. However, this is not limited to this. For example, the thermal resistance R of the refrigerant may be controlled by using a mixed liquid obtained by mixing multiple liquids with different thermal conductivities as the refrigerant.

[0110] FIG. 18 is a diagram illustrating another example of a configuration for adjusting the temperature of the main body 111 according to the embodiment. The chiller unit 114 separately stores two types of liquids with different specific gravities and thermal conductivities. For example, the chiller unit 114 has two tanks 114a and 114b, and a first liquid and a second liquid are separately stored in the tanks 114a and 114b. The first liquid and the second liquid are preferably liquids that do not dissolve in each other. For example, the first liquid may be a fluorine-based inert liquid such as FC3283 or a high-performance liquid such as Novec7200. The second liquid may be water, ethylene glycol, or silicone oil. The chiller unit 114 is capable of changing the mixing ratio of the two types of liquids stored in the tanks 114a and 114b, and supplies the mixed liquid as a refrigerant. For example, chiller unit 114 has supply ports 114c and 114d that individually supply two types of liquid stored in tanks 114a and 114b. One end of pipe 113a branches and is connected to supply ports 114c and 114d, respectively. The two types of liquid supplied from supply ports 114c and 114d to pipe 113a are mixed by agitation caused by the flow before reaching flow path 1110a from pipe 113a. Chiller unit 114 is capable of changing the flow rates of the two types of liquid supplied from supply ports 114c and 114d, and by changing the flow rates of the two types of liquid, the mixing ratio of the two types of liquid is changed. The mixed liquid supplied from chiller unit 114 passes through pipe 113a, flow path 1110a, and pipe 113b and returns to chiller unit 114. The chiller unit 114 stores the returned mixed liquid in a recovery tank, separates the mixed liquid into two types of liquid based on the difference in specific gravity, and returns them to tanks 114a and 114b, respectively.

[0111] The control unit 2 controls the heat transfer coefficient h by changing the mixture ratio. For example, the control unit 2 controls the chiller unit 114 to change the flow rates of the two types of liquid supplied from the supply ports 114c and 114d, thereby changing the mixture ratio of the mixed liquid and controlling the heat transfer coefficient h. For example, the control unit 2 sets the heat transfer coefficient h to a first value when the temperature of the substrate W is increased, as shown in FIG. 7(A). Furthermore, the control unit 2 sets the heat transfer coefficient h to a second value greater than the first value when the temperature of the substrate W is increased, as shown in FIG. 7(B). Furthermore, the control unit 2 sets the heat transfer coefficient h to a third value greater than the first and second values ​​when the temperature of the substrate W is decreased, as shown in FIG. 7(C). This allows the plasma processing apparatus 1 to quickly increase the temperature of the substrate W when the temperature of the substrate W is increased. Furthermore, the plasma processing apparatus 1 can reduce the heat dissipation capacity of the main body 111, thereby reducing the amount of heat generated by the heater HT required to increase the temperature of the substrate W. This allows the plasma processing apparatus 1 to reduce the power consumption of the heater HT when the temperature of the substrate W is increased. Furthermore, the plasma processing apparatus 1 can quickly cool the substrate W when lowering the temperature of the substrate W. The chiller unit 114 may be capable of changing the mixing ratio of three or more types of liquids having different specific gravities and thermal conductivities, and may circulate the mixed liquid of the three or more types of liquids as a refrigerant through the flow path 1110a. The control unit 2 may control the heat transfer coefficient h by changing the mixing ratio of the three or more types of liquids.

[0112] As described above, the plasma processing system according to the embodiment includes the plasma processing chamber 10 (substrate processing chamber), the base 1110, a circulation unit (pipes 113a, 113b and chiller unit 114), and the bubble supply unit 70. The base 1110 is disposed in the plasma processing chamber 10, supports the electrostatic chuck 1111 (substrate placement unit) on which the substrate W is placed, and has a flow path 1110a (coolant flow path). The circulation unit is connected to the flow path 1110a and circulates the coolant through the flow path 1110a. The bubble supply unit 70 supplies bubbles to the coolant in the flow path 1110a. This allows the plasma processing system to control the thermal resistance R of the coolant.

[0113] Furthermore, the bubble supply unit 70 supplies microbubbles with a diameter of 100 μm or less as the bubbles. This allows the plasma processing system to stably circulate the coolant containing the microbubbles through the flow path 1110a. Furthermore, by circulating the coolant containing the microbubbles through the flow path 1110a, the plasma processing system can change the thickness of the thermal boundary layer formed near the wall surface of the flow path 1110a, thereby controlling the thermal resistance R of the coolant.

[0114] Furthermore, the bubble supply unit 70 supplies bubbles to the coolant in the flow path 1110a with a void ratio of 1% or less, which allows the plasma processing system to change the thickness of the thermal boundary layer formed near the wall surface of the flow path 1110a, thereby controlling the thermal resistance R of the coolant.

[0115] The base 1110 has a supply port 1110b formed at one end of the flow path 1110a, through which a coolant is supplied from the circulation unit, and a discharge port 1110c formed at the other end of the flow path 1110a, through which the coolant is discharged. The bubble supply unit 70 supplies bubbles to the coolant supplied from the circulation unit to the supply port 1110b. This allows the plasma processing system to stably supply the coolant containing bubbles to the flow path 1110a.

[0116] The plasma processing system further includes a bubble removal unit 120 on a path where the coolant returns from the flow path 1110a to the circulation unit. The bubble removal unit 120 removes bubbles from the coolant. This allows the plasma processing system to remove bubbles from the coolant returning from the flow path 1110a to the circulation unit.

[0117] The plasma processing system further includes a controller 2. The controller 2 controls the bubble supplier 70 so that bubbles are supplied to the coolant at least when the substrate W is heated. This allows the plasma processing system to increase the thickness of the thermal boundary layer formed near the wall surface of the flow path 1110a when the substrate W is heated, thereby controlling the thermal resistance R of the coolant.

[0118] Furthermore, the control unit 2 controls the circulation unit so that the flow rate of the coolant flowing through the flow path 1110a is greater when cooling the substrate W than when heating the substrate W. This allows the plasma processing system to make the thickness of the thermal boundary layer formed near the wall surface of the flow path 1110a thinner when cooling the substrate W than when heating the substrate W, thereby improving the heat transfer performance with the coolant. This allows the plasma processing system to quickly cool the substrate W when lowering the temperature of the substrate W.

[0119] The electrostatic chuck 1111 also includes a heater HT. The heater HT heats the substrate W. This allows the plasma processing system to reduce the power consumption of the heater HT when raising the temperature of the substrate W.

[0120] Moreover, the plasma processing system according to the embodiment includes a plasma processing chamber 10 (substrate processing chamber), a base 1110, a circulation unit (pipes 113a, 113b and a chiller unit 114), and a controller 2. The base 1110 is disposed in the plasma processing chamber 10, supports an electrostatic chuck 1111 (substrate placement unit) on which a substrate W is placed, and has a flow path 1110a formed thereon. The circulation unit is connected to the flow path 1110a and circulates a coolant through the flow path 1110a. The controller 2 executes processes including the steps of: setting a heat transfer coefficient h between the coolant in the flow path 1110a and the flow path 1110a to a first value when the temperature of the substrate W is increasing; setting the heat transfer coefficient h between the coolant and the flow path 1110a to a second value greater than the first value when the plasma processing is performed on the substrate W; and setting the heat transfer coefficient h between the coolant and the flow path 1110a to a third value greater than the first and second values ​​when the temperature of the substrate W is decreasing. This allows the plasma processing system to control the thermal resistance R of the coolant. Furthermore, the plasma processing system can increase the thermal resistance R of the coolant when the temperature of the substrate W is increasing, thereby enabling the temperature of the substrate W to be increased quickly. Furthermore, the plasma processing system can decrease the thermal resistance R of the coolant when the temperature of the substrate W is decreasing, thereby enabling the temperature of the substrate W to be decreased quickly.

[0121] The plasma processing system according to the embodiment further includes a bubble supply unit 70. The bubble supply unit 70 supplies bubbles to the coolant in the flow path 1110a. This allows the plasma processing system to increase the thickness of the thermal boundary layer formed near the wall surface of the flow path 1110a, thereby controlling the thermal resistance R of the coolant.

[0122] Furthermore, the flow path 1110a has a plurality of linear convex portions arranged parallel to the surface of the wall. The height hi of the convex portions is smaller than the thickness of the thermal boundary layer formed near the wall surface of the flow path 1110a when the temperature of the substrate W is increasing, and is larger than the thickness of the thermal boundary layer when the temperature of the substrate W is decreasing. This allows the plasma processing system to maintain heat transfer performance with the coolant when the temperature of the substrate W is increasing at the same level as when the wall surface is smooth. Furthermore, when the temperature of the substrate W is decreasing, the heat transfer performance with the coolant can be improved compared to when the wall surface is smooth.

[0123] The plasma processing system further includes valve 117, the opening of which is adjustable, in pipe 113a that supplies a coolant to flow path 1110a. Controller 2 controls the heat transfer coefficient h by periodically changing the opening of valve 117 at a frequency of 1 Hz or more. This allows the plasma processing system to control the thermal resistance R of the coolant.

[0124] The circulation unit can change the mixing ratio of multiple liquids with different thermal conductivities, and circulates the mixed liquid as a coolant through flow path 1110a. Control unit 2 changes the mixing ratio to control the heat transfer coefficient h. This allows the plasma processing system to control the thermal resistance R of the coolant.

[0125] It should be noted that the disclosed embodiments are illustrative in all respects and should not be considered limiting. Indeed, the above-described embodiments may be embodied in various forms. Furthermore, the above-described embodiments may be omitted, substituted, or modified in various forms without departing from the scope and spirit of the appended claims.

[0126] In the above embodiment, the plasma processing is performed on a semiconductor wafer as the substrate W, but the present invention is not limited to this. The substrate W may be a glass substrate or the like.

[0127] In the above embodiment, a plasma processing system has been described as an example of a substrate processing apparatus, but the present invention is not limited to this. The substrate processing apparatus may be any apparatus that supports a substrate support portion on which a substrate is placed and cools the base by circulating a coolant through a flow path formed in the base. For example, the substrate processing apparatus may be a plasma etching apparatus, a film forming apparatus, a modification apparatus, an ashing apparatus, or other heat treatment apparatus.

[0128] In addition, the following supplementary notes are disclosed regarding the above-described embodiment.

[0129] (Appendix 1) a substrate processing chamber; a base disposed in the substrate processing chamber, supporting a substrate placement portion on which a substrate is placed, and having a coolant flow path formed therein; a circulation unit connected to the refrigerant flow path and circulating the refrigerant through the refrigerant flow path; a bubble supply unit that supplies bubbles to the refrigerant in the refrigerant flow path; A substrate processing apparatus comprising:

[0130] (Appendix 2) The bubble supply unit supplies microbubbles having a diameter of 100 μm or less as the bubbles. 10. The substrate processing apparatus according to claim 1.

[0131] (Appendix 3) The bubble supply unit supplies bubbles to the refrigerant in the refrigerant flow path at a void ratio of 1% or less. 3. The substrate processing apparatus according to claim 1 or 2.

[0132] (Appendix 4) the base has a supply port formed at one end of the refrigerant flow path through which the refrigerant is supplied from the circulation unit, and a discharge port formed at the other end of the refrigerant flow path through which the refrigerant is discharged; The bubble supply unit supplies bubbles to the refrigerant supplied from the circulation unit to the supply port. 4. The substrate processing apparatus according to any one of Supplementary Notes 1 to 3.

[0133] (Appendix 5) a bubble removal section for removing the bubbles from the refrigerant, in a path through which the refrigerant returns to the circulation section from the refrigerant flow path; 5. The substrate processing apparatus according to any one of claims 1 to 4, further comprising:

[0134] (Appendix 6) Further comprising a control unit, The control unit controls the bubble supply unit so that the bubbles are supplied to the coolant at least when the substrate is heated. 6. The substrate processing apparatus according to any one of claims 1 to 5, further comprising:

[0135] (Appendix 7) The control unit controls the circulation unit so that the flow rate of the coolant flowing through the coolant flow path is greater when cooling the substrate than when heating the substrate. 7. The substrate processing apparatus according to claim 6.

[0136] (Appendix 8) the substrate placement part includes a heater, The substrate is heated by the heater. 8. The substrate processing apparatus according to claim 6 or 7.

[0137] (Appendix 9) a substrate processing chamber; a base disposed in the substrate processing chamber, supporting a substrate placement portion on which a substrate is placed, and having a coolant flow path formed therein; a circulation unit connected to the refrigerant flow path and circulating the refrigerant through the refrigerant flow path; a control unit, The control unit setting a heat transfer coefficient between the coolant in the coolant flow path and the coolant flow path to a first value when the temperature of the substrate is rising; setting a heat transfer coefficient between the coolant and the coolant flow path to a second value greater than the first value during substrate processing of the substrate; and setting a heat transfer coefficient between the coolant and the coolant flow path to a third value greater than the first value and the second value when the temperature of the substrate is lowered. Substrate processing equipment.

[0138] (Appendix 10) a bubble supply unit that supplies bubbles to the refrigerant in the refrigerant flow path; 10. The substrate processing apparatus according to claim 9, further comprising:

[0139] (Appendix 11) The coolant flow path has a plurality of linear protrusions arranged parallel to each other on the surface of the wall. 11. The substrate processing apparatus according to claim 9 or 10.

[0140] (Appendix 12) The height of the convex portion is smaller than the thickness of a thermal boundary layer formed in the vicinity of the wall surface of the coolant flow path when the temperature of the substrate is increased, and is larger than the thickness of the thermal boundary layer when the temperature of the substrate is decreased. 12. The substrate processing apparatus according to claim 11.

[0141] (Appendix 13) a valve whose opening degree is adjustable in a pipe that supplies a refrigerant to the refrigerant flow path; The control unit controls the heat transfer coefficient by periodically changing the valve opening at a frequency of 1 Hz or more. 10. The substrate processing apparatus according to claim 9.

[0142] (Appendix 14) the circulation unit is capable of changing a mixing ratio of a plurality of liquids having different thermal conductivities, and circulates a mixed liquid obtained by mixing the plurality of liquids as the refrigerant through the refrigerant flow path; The control unit controls the heat transfer coefficient by changing the mixture ratio. 10. The substrate processing apparatus according to claim 9. [Explanation of symbols]

[0143] 1. Plasma processing equipment 2. Control Unit 2a Computer 2a1 Processing section 2a2 Storage section 2a3 communication interface 10 Plasma Processing Chamber 11 Substrate support 12 Plasma generation unit 60 Heater power supply 70 Bubble supply section 71, 113a, 113b, 115, 123 Piping 72, 116, 117, 123a valves 111 Main body 111a Central area 111b Annular region 112 Ring Assembly 114 Chiller unit 114a, 114b, 121 Tank 114c, 114d supply port 117a Valve body 120 Air bubble removal section 122 Dry Pump 124, HT heater 1110 Foundation 1110a flow channel 1110b Supply port 1110c outlet 1111 Electrostatic chuck 1111a Ceramic components 1111b Electrostatic electrode 1113 Riblet structure 1113a Convex part

Claims

1. a substrate processing chamber; a base disposed in the substrate processing chamber, supporting a substrate placement portion on which a substrate is placed, and having a coolant flow path formed therein; a circulation unit connected to the refrigerant flow path and circulating the refrigerant through the refrigerant flow path; a bubble supply unit that supplies bubbles to the refrigerant in the refrigerant flow path; A substrate processing apparatus comprising:

2. The air bubble supply unit supplies microbubbles having a diameter of 100 μm or less as the air bubbles. The substrate processing apparatus according to claim 1 .

3. The bubble supply unit supplies bubbles to the refrigerant in the refrigerant flow path at a void ratio of 1% or less. The substrate processing apparatus according to claim 1 or 2.

4. the base has a supply port formed at one end of the refrigerant flow path through which the refrigerant is supplied from the circulation unit, and a discharge port formed at the other end of the refrigerant flow path through which the refrigerant is discharged, The bubble supply unit supplies bubbles to the refrigerant supplied from the circulation unit to the supply port. The substrate processing apparatus according to claim 1 or 2.

5. a bubble removal section for removing the bubbles from the refrigerant, in a path through which the refrigerant returns to the circulation section from the refrigerant flow path; The substrate processing apparatus according to claim 1 or 2, further comprising:

6. Further comprising a control unit, The control unit controls the bubble supply unit so that the bubbles are supplied to the coolant at least when the substrate is heated. The substrate processing apparatus according to claim 1 or 2, further comprising:

7. The control unit controls the circulation unit so that the flow rate of the coolant flowing through the coolant flow path is greater when cooling the substrate than when heating the substrate. The substrate processing apparatus according to claim 6 .

8. the substrate placement part includes a heater, The substrate is heated by the heater. The substrate processing apparatus according to claim 6 .

9. a substrate processing chamber; a base disposed in the substrate processing chamber, supporting a substrate placement portion on which a substrate is placed, and having a coolant flow path formed therein; a circulation unit connected to the refrigerant flow path and circulating the refrigerant through the refrigerant flow path; a control unit, The control unit setting a heat transfer coefficient between the coolant in the coolant flow path and the coolant flow path to a first value when the temperature of the substrate is rising; setting a heat transfer coefficient between the coolant and the coolant flow path to a second value greater than the first value during substrate processing of the substrate; and setting a heat transfer coefficient between the coolant and the coolant flow path to a third value greater than the first value and the second value when the temperature of the substrate is lowered. Substrate processing equipment.

10. a bubble supply unit that supplies bubbles to the refrigerant in the refrigerant flow path; The substrate processing apparatus of claim 9 further comprising:

11. The coolant flow path has a plurality of linear protrusions arranged parallel to each other on the surface of the wall. The substrate processing apparatus according to claim 9 .

12. The height of the convex portion is smaller than the thickness of a thermal boundary layer formed in the vicinity of the wall surface of the coolant flow path when the temperature of the substrate is increased, and is larger than the thickness of the thermal boundary layer when the temperature of the substrate is decreased. The substrate processing apparatus according to claim 11 .

13. a valve whose opening degree is adjustable in a pipe that supplies a refrigerant to the refrigerant flow path; The control unit controls the heat transfer coefficient by periodically changing the opening of the valve at a frequency of 1 Hz or more. The substrate processing apparatus according to claim 9 .

14. the circulation unit is capable of changing a mixing ratio of a plurality of liquids having different thermal conductivities, and circulates a mixed liquid obtained by mixing the plurality of liquids as the refrigerant through the refrigerant flow path; The control unit controls the heat transfer coefficient by changing the mixture ratio. The substrate processing apparatus according to claim 9 .

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