Plasma treatment device

Abstract

A plasma treatment device (1) comprises a chamber, a substrate support part, and an upper electrode assembly. Plasma is generated inside the chamber. The substrate support part is provided inside the chamber and supports a substrate. The upper electrode assembly includes an upper electrode (14) that is disposed opposite from the substrate support part and a cooling plate (15) that is provided above the upper electrode (14) and that has formed therein a gas diffusion chamber (16) in which a supplied gas spreads. A plurality of first holes (14c) are formed in the upper electrode (14). A plurality of second holes (15c) that are in communication with the plurality of first holes (14c) are formed in a first surface (14b) of the cooling plate (15) on the upper electrode (14) side of the gas diffusion chamber (16). A third hole (16ad) that reaches the upper electrode (14) is formed in the first surface (14b).

Description

Plasma processing equipment

[0001] The present disclosure relates to a plasma processing apparatus.

[0002] Patent Document 1 listed below discloses "a temperature control method for an upper electrode of a capacitively coupled plasma processing apparatus, comprising a step of cooling the upper electrode and a step of increasing the temperature of the upper electrode, wherein a flow path having an inlet and an outlet is formed in the upper electrode, the upper electrode constituting an evaporator, a compressor, a condenser, and an expansion valve are connected in this order between the outlet and the inlet of the flow path, and a shunt valve is connected between the output of the compressor and the inlet so as to bypass the condenser and the expansion valve, wherein in the step of cooling the upper electrode, a refrigerant is supplied to the flow path via the compressor, the condenser, and the expansion valve, and in the step of increasing the temperature of the upper electrode, the shunt valve is opened and the upper electrode is heated."

[0003] Japanese Patent Application Laid-Open No. 2019-192728

[0004] The present disclosure provides a technique for lowering the temperature of the upper electrode.

[0005] A plasma processing apparatus according to one aspect of the present disclosure includes a chamber, a substrate support, and an upper electrode assembly. The chamber generates plasma therein. The substrate support is provided within the chamber and supports a substrate. The upper electrode assembly includes an upper electrode disposed opposite the substrate support, and a cooling plate provided on the upper electrode and having a gas diffusion chamber formed therein for diffusing a supplied gas. The upper electrode has a plurality of first holes formed therein. The cooling plate has a first surface on the upper electrode side of the gas diffusion chamber formed with a plurality of second holes communicating with the plurality of first holes, and a third hole formed in the first surface reaching the upper electrode.

[0006] According to the present disclosure, the upper electrode can be cooled to a low temperature.

[0007] FIG. 1 is a diagram for explaining an example of the configuration of a capacitively coupled plasma processing apparatus. FIG. 2 is a cross-sectional view showing an example of a schematic configuration of a shower head according to an embodiment. FIG. 3 is a diagram showing an example of a schematic configuration of a gas diffusion chamber of a shower head according to an embodiment. FIG. 4 is a diagram showing another example of a schematic configuration of a gas diffusion chamber of a shower head according to an embodiment. FIG. 5 is a diagram showing another example of a schematic configuration of a gas diffusion chamber of a shower head according to an embodiment. FIG. 6A is a diagram showing an example of a case where the position at which the diameter of a gas hole is changed according to an embodiment is changed. FIG. 6B is a diagram showing an example of a case where the position at which the diameter of a gas hole is changed according to an embodiment is changed. FIG. 7 is a diagram showing an example of a schematic configuration of a gas diffusion chamber of a shower head according to an embodiment. FIG. 8 is a diagram showing an example of a schematic configuration of a gas diffusion chamber of a shower head according to a comparative example.

[0008] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the plasma processing apparatus disclosed in the present application will be described in detail below with reference to the accompanying drawings. However, the plasma processing apparatus disclosed in the present application is not limited to the present embodiments.

[0009] A plasma processing apparatus that generates plasma in a chamber and performs plasma processing has been known. The plasma processing apparatus has an upper electrode assembly at the top of the chamber, the upper electrode assembly including an upper electrode facing the interior of the chamber and a cooling plate for cooling the upper electrode.

[0010] The upper electrode may become so hot due to heat input from the plasma that it may crack, so plasma processing apparatuses cool the upper electrode with a cooling plate.

[0011] However, as the plasma energy increases, it is expected that the upper electrode will reach a high temperature, and therefore, a technology for lowering the temperature of the upper electrode is desired.

[0012] [Embodiment] [Apparatus Configuration] An example of a plasma processing apparatus according to the present disclosure will be described. In the embodiment described below, a case where the plasma processing apparatus according to the present disclosure is used as a plasma processing system having a system configuration will be described as an example.

[0013] An example of the configuration of a plasma processing system will be described below: Fig. 1 is a diagram for explaining an example of the configuration of a capacitively coupled plasma processing apparatus.

[0014] The plasma processing system includes a capacitively coupled plasma processing apparatus 1 and a controller 2. 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 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 has at least one gas inlet for supplying at least one processing gas to the plasma processing space 10s and at least one gas outlet for exhausting gas from the plasma processing space 10s. 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.

[0015] 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.

[0016] In one embodiment, the main body 111 includes a base 1110 and an electrostatic chuck 1111. 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 (Radio Frequency) power supply 31 and / or a DC (Direct Current) power supply 32 (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 (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. Furthermore, the electrostatic electrode 1111b may function as a lower electrode. Therefore, the substrate support 11 includes at least one lower electrode.

[0017] 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.

[0018] 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 passage 1110a, or a combination thereof. A heat transfer fluid such as brine or a gas flows through the flow passage 1110a. In one embodiment, the flow passage 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 configured to supply a heat transfer gas to a gap between the backside of the substrate W and the central region 111a.

[0019] The showerhead 13 is provided on the ceiling wall of the plasma processing chamber 10. The showerhead 13 is supported on the upper part of the plasma processing chamber 10 via an insulating member 12. The showerhead 13 is configured to introduce at least one processing gas from a gas supply unit 20 into the plasma processing space 10s.

[0020] The shower head 13 includes an upper electrode 14 that serves as an electrode plate, and a cooling plate 15. The shower head 13 is an example of an upper electrode assembly of the present disclosure.

[0021] The upper electrode 14 is provided at the top of the plasma processing chamber 10, facing the substrate support 11. The upper electrode 14 is also referred to as a CEL (Cover Electrode). The upper electrode 14 is formed in a disk shape. The upper electrode 14 is preferably made of a low-resistance conductor or semiconductor. Examples of suitable materials for the upper electrode 14 include silicon and SiC. Silicon is a brittle material that breaks with even slight deformation when subjected to external force. For this reason, if the upper electrode 14 is made of silicon, it may break if the allowable stress is exceeded.

[0022] The lower surface 14a of the upper electrode 14 faces the substrate support part 11. A plurality of gas holes 14c penetrating the upper surface 14b and the lower surface 14a are formed in the upper electrode 14. The gas holes 14c are an example of the first holes of the present disclosure.

[0023] The cooling plate 15 is provided on the upper electrode 14. The shower head 13 is formed in a flat cylindrical shape with a diameter larger than that of the upper electrode 14. The cooling plate 15 is placed on the upper surface 14b of the upper electrode 14 and detachably supports the upper electrode 14 from above. The cooling plate 15 is made of a conductive material, for example, aluminum whose surface has been anodized.

[0024] A gas diffusion chamber 16 consisting of a disk-shaped space is formed inside the cooling plate 15. The gas diffusion chamber 16 is partitioned into multiple spaces. For example, the gas diffusion chamber 16 is provided with an annular partition member 17. In the plasma processing apparatus 1 according to this embodiment, the partition member 17 radially partitions the gas diffusion chamber 16 into multiple spaces. For example, the gas diffusion chamber 16 is partitioned into three zones, gas diffusion chambers 16a-16c, corresponding to a center portion, which is the central portion of the substrate W, a middle portion, which is the intermediate portion between the center and the periphery of the substrate W, and an edge portion, which is the periphery of the substrate W. The gas diffusion chamber 16a is a disk-shaped space. The gas diffusion chamber 16b is a ring-shaped space surrounding the gas diffusion chamber 16a. The gas diffusion chamber 16c is a ring-shaped space surrounding the gas diffusion chamber 16b. The cooling plate 15 has multiple gas holes 15c formed below the gas diffusion chambers 16a, 16b, and 16c, respectively. The plurality of gas holes 15c are formed so as to overlap with and communicate with the plurality of gas holes 14c in the upper electrode 14. The gas holes 15c are provided in a one-to-one correspondence with the gas holes 14c in the upper electrode 14. The gas holes 15c are an example of the second holes of the present disclosure.

[0025] The cooling plate 15 is configured to be coolable. For example, the cooling plate 15 has a flow path (not shown) formed therein above the gas diffusion chamber 16. A coolant such as brine or gas flows through the flow path of the cooling plate 15. The cooling plate 15 is configured to be coolable by flowing the coolant through the flow path. Note that the cooling plate 15 may not have an internal flow path, but may be cooled by an air-cooling method using heat exchange with the atmosphere outside the plasma processing chamber 10, or by a water-cooled jacket or Peltier element provided on the upper surface of the cooling plate 15. The cooling plate 15 cools the upper electrode 14.

[0026] The cooling plate 15 is formed with gas supply ports 18a to 18c for introducing process gas into the gas diffusion chambers 16a to 16c.

[0027] A gas pipe 23 is connected to the gas supply unit 20. The gas pipe 23 branches and is connected to the gas supply ports 18a-18c, respectively. The gas supply unit 20 supplies various process gases used in plasma processing to the gas supply ports 18a-18c via the gas pipe 23. The process gases supplied to the gas supply ports 18a-18c flow into the gas diffusion chambers 16a-16c, are diffused in the gas diffusion chambers 16a-16c, and are supplied in a shower-like manner to the plasma processing space 10s via the gas holes 15c and 14c. In addition to the shower head 13, the gas introduction unit may include one or more side gas injectors (SGIs) attached to one or more openings formed in the sidewall 10a.

[0028] 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 a gas line 23 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 one or more flow modulation devices that modulate or pulse the flow rate of the at least one process gas.

[0029] 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 process gas supplied to the plasma processing space 10s. Therefore, the RF power supply 31 can function as at least a part of a plasma generating unit configured to generate a plasma from one or more process gases in the plasma processing chamber 10. Furthermore, by supplying a bias RF signal to the at least one lower electrode, a bias potential is generated on the substrate W, thereby attracting ion components in the formed plasma to the substrate W.

[0030] 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.

[0031] The second RF generator 31b is coupled to at least one lower electrode via at least one impedance matching circuit and is 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 generator 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.

[0032] 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 the at least one lower electrode and configured to generate a first DC signal. The generated first bias DC signal is applied to the at least one lower electrode. In one embodiment, the second DC generator 32b is connected to the 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.

[0033] In various embodiments, at least one of 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 pulse waveform. In one embodiment, a waveform generator for generating the 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.

[0034] 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 in the plasma processing space 10s is regulated by the pressure regulating valve. The vacuum pump may include a turbomolecular pump, a dry pump, or a combination thereof.

[0035] 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. This 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).

[0036] Next, a more detailed configuration of the shower head 13 according to the embodiment will be described. Fig. 2 is a cross-sectional view showing an example of a schematic configuration of the shower head 13 according to the embodiment. In Fig. 2, the central axis of the upper electrode 14 and the cooling plate 15 is indicated as L1.

[0037] The cooling plate 15 is provided on the upper electrode 14 with its central axis aligned with that of the upper electrode 14. Gas diffusion chambers 16a-16c are formed inside the cooling plate 15. Gas flow paths 19a-19c are also formed inside the cooling plate 15 for flowing process gas from the gas supply ports 18a-18c to the gas diffusion chambers 16a-16c. Outlets 16ac-16cc are formed on the upper surfaces 16aa-16ca of the gas diffusion chambers 16a-16c, through which the process gas flows after flowing through the gas flow paths 19a-19c. The outlet 16ac is formed in the center of the upper surface 16aa of the gas diffusion chamber 16a.

[0038] The upper electrode 14 has a plurality of gas holes 14c formed in the area below the gas diffusion chambers 16a to 16c of the cooling plate 15.

[0039] In the cooling plate 15, a plurality of gas holes 15c are formed in the lower surfaces 16ab-16cb of the gas diffusion chambers 16a-16c. The lower surfaces 16ab-16cb are an example of a first surface of the present disclosure. The plurality of gas holes 15c are formed to overlap with the plurality of gas holes 14c of the upper electrode 14, respectively, and are in communication with the plurality of gas holes 14c. In one embodiment, the gas holes 14c and the gas holes 15c are formed in a circular shape with the same diameter. Note that the gas holes 14c and the gas holes 15c may be formed in a circular shape with different diameters. In one embodiment, the diameter of the gas holes 15c is larger than the diameter of the gas holes 14c.

[0040] Furthermore, a hole 16ad is formed in the lower surface 16ab of the gas diffusion chamber 16a of the cooling plate 15, reaching the upper electrode 14. The hole 16ad is formed in the center of the gas diffusion chamber 16a below the outlet 16ac. The hole 16ad is an example of a third hole of the present disclosure.

[0041] In the shower head 13, by forming the holes 16ad in the cooling plate 15 in this manner, the upper surface 14b of the upper electrode 14 is exposed to the gas diffusion chamber 16a through the holes 16ad, and the upper surface 14b is exposed to the process gas. As a result, in the shower head 13 according to the embodiment, heat is exchanged between the upper electrode 14 and the process gas, and the upper electrode 14 is cooled, so that the temperature of the upper electrode 14 can be reduced.

[0042] The center of the upper electrode 14 tends to become hot due to heat input from the plasma. For this reason, the shower head 13 according to the embodiment is configured to form a hole 16ad in the center of the gas diffusion chamber 16a to cool the center of the upper electrode 14. This allows the shower head 13 according to the embodiment to lower the temperature of the center of the upper electrode 14, which tends to become hot.

[0043] 3 is a diagram showing an example of a schematic configuration of the gas diffusion chamber 16a of the shower head 13 according to this embodiment. Fig. 3 shows an enlarged view of the vicinity of the center of the gas diffusion chamber 16a of the shower head 13, which is indicated by the dashed line L2 in Fig. 2 .

[0044] In the shower head 13 according to this embodiment, a gas hole non-penetrating region A1 is formed below the central portion of the gas diffusion chamber 16a, and a gas hole penetrating region A2 is formed below the peripheral portion surrounding the central portion. Gas holes 14c and gas holes 15c are formed in the gas hole penetrating region A2 of the shower head 13. Furthermore, in the gas hole non-penetrating region A1 of the shower head 13, gas holes 14c and gas holes 15c are not formed, and hole 16ad is formed instead.

[0045] The cooling plate 15 has an outlet 16ac formed in the center of the upper surface 16aa of the gas diffusion chamber 16a. A hole 16ad is formed below the outlet 16ac. One hole 16ad is formed, smaller than the size of the gas hole non-penetrating region A1 and larger than the cross-sectional size of the outlet 16ac. The process gas flowing from the outlet 16ac to the gas diffusion chamber 16a flows mainly to the upper surface 14b of the upper electrode 14 exposed by the hole 16ad. As a result, the shower head 13 according to the embodiment increases heat exchange between the upper electrode 14 and the process gas, thereby further cooling the upper electrode 14, thereby enabling the upper electrode 14 to be cooled further.

[0046] In the gas diffusion chamber 16a, the process gas flowing out from the outlet 16ac diffuses, but the pressure near the center where the outlet 16ac is formed becomes high. Figure 3 shows a pattern of the general pressure distribution when the process gas is flowing. When the process gas is flowing, the inside of the gas diffusion chamber 16a becomes a high-pressure region where the pressure is higher near the center.

[0047] The cooling plate 15 has holes 16ad formed below the outlets 16ac, which allows a high-pressure region to contact the upper surface 14b of the upper electrode 14 through the holes 16ad, thereby increasing the pressure of the process gas on the upper surface 14b of the upper electrode 14. As a result, in the shower head 13 according to the embodiment, heat exchange between the upper electrode 14 and the process gas increases, and the upper electrode 14 is further cooled, thereby enabling the upper electrode 14 to be further cooled.

[0048] In the above embodiment, a single hole 16ad is formed in the center of the gas diffusion chamber 16a of the shower head 13. However, this is not limiting. For example, multiple holes 16ad may be formed in the center of the gas diffusion chamber 16a of the shower head 13. FIG. 4 is a diagram showing another example of the schematic configuration of the gas diffusion chamber 16a of the shower head 13 according to the embodiment. FIG. 4 shows a pattern illustrating a general pressure distribution when a process gas is flowing. In the shower head 13, the gas hole non-penetrating region A1 does not have gas holes 14c and gas holes 15c, but instead has multiple holes 16ad. The hole 16ad is circular and has the same diameter as the gas holes 15c. The process gas flowing from the outlet 16ac into the gas diffusion chamber 16a flows mainly onto the upper surface 14b of the upper electrode 14 exposed by the multiple holes 16ad. The upper electrode 14 is cooled by heat exchange with the process gas flowing from the outlet 16ac. Therefore, the shower head 13 according to the embodiment can lower the temperature of the upper electrode 14 even when configured as shown in FIG.

[0049] In the above embodiment, the gas holes 14c and 15c have the same diameter. However, this is not limiting. The diameters of the gas holes 14c and 15c may be changed. FIG. 5 is a diagram showing another example of the schematic configuration of the gas diffusion chamber 16a of the shower head 13 according to the embodiment. FIG. 5 shows a pattern illustrating a general pressure distribution when a process gas is flowing. The diameter of the gas holes 14c on the cooling plate 15 side is smaller than the diameter on the substrate support 11 side. The diameter of the gas holes 15c is the same as the diameter of the gas holes 14c on the cooling plate 15 side. By changing the diameter of the gas holes 14c in this way, the shower head 13 according to the embodiment can increase the pressure difference between the gases flowing through the gas holes 14c and 15c, thereby increasing the pressure in the gas diffusion chamber 16a. As a result, the shower head 13 according to the embodiment can increase heat exchange between the upper electrode 14 and the process gas, thereby further cooling the upper electrode 14, thereby further lowering the temperature of the upper electrode 14.

[0050] Furthermore, when changing the diameters of the gas holes 14c and 15c, the pressure in the gas diffusion chamber 16a can be changed by changing the diameter change position. FIGS. 6A and 6B are diagrams illustrating an example of changing the diameter change position of the gas holes 14c according to the embodiment. FIGS. 6A and 6B show a schematic pressure distribution pattern when a process gas is flowing. In FIG. 6B, the change position for reducing the diameter of the gas holes 14c is located closer to the substrate support 11 than in FIG. 6A. In this case, the conductance of the gas holes 14c and 15c is lower in the configuration of FIG. 6B than in the configuration of FIG. 6A. Therefore, the pressure on the gas diffusion chamber 16a side can be higher in the configuration of FIG. 6B than in the configuration of FIG. 6A. As a result, the configuration of FIG. 6B increases heat exchange between the upper electrode 14 and the process gas, cooling the upper electrode 14 more effectively, thereby lowering the temperature of the upper electrode 14.

[0051] In the above embodiment, the hole 16ad reaching the upper electrode 14 is formed only in the gas diffusion chamber 16a. However, this is not limiting. Holes reaching the upper electrode 14 may be formed in each of the gas diffusion chambers 16a-16c.

[0052] In the above embodiment, the holes 16ad reaching the upper electrode 14 are formed in a portion of the lower surface 16ab of the gas diffusion chamber 16a. However, this is not limiting. Holes reaching the upper electrode 14 may be formed in the entire lower surfaces 16ab-16cb of the gas diffusion chambers 16a-16c. For example, holes reaching the upper electrode 14, gas holes 14c, and gas holes 15c may be formed alternately.

[0053] In the above embodiment, the gas diffusion chamber 16 is divided into three spaces (gas diffusion chambers 16a-16c). However, this is not limitative. The gas diffusion chamber 16 may be a single space without being divided into sections. Furthermore, the number of zones dividing the gas diffusion chamber 16 is not limited to three, but may be two, four, or more.

[0054] Here, an example of the effect of lowering the temperature of the upper electrode 14 will be described. In the following, a case where the gas diffusion chamber 16 is not partitioned but is formed as a single space will be described. FIG. 7 is a diagram showing an example of a schematic configuration of the gas diffusion chamber 16 of the shower head 13 according to the embodiment. FIG. 7 shows a pattern illustrating a general pressure distribution when a process gas is flowed. In the shower head 13 according to the embodiment shown in FIG. 7, holes 16d reaching the upper electrode 14, gas holes 14c, and gas holes 15c are alternately formed across the entire lower surface 16e of the gas diffusion chamber 16. Hole 16e is an example of a first surface according to the present disclosure. Hole 16d is an example of a third hole according to the present disclosure. The gas holes 14c, 15c, and 16d are formed in a circular shape with the same diameter. Hereinafter, the ratio of the number of gas holes 15c to the number of gas holes 15c and holes 16d is referred to as the "gas hole ratio." In FIG. 7, the gas hole ratio is 0.5.

[0055] FIG. 8 is a diagram showing an example of a schematic configuration of the gas diffusion chamber 16 of the shower head 13 according to the comparative example. FIG. 8 shows a pattern of a schematic pressure distribution when a processing gas is flowed. In the shower head 13 according to the comparative example shown in FIG. 8, the hole 16d in FIG. 7 is replaced with gas holes 14c and 15c. In FIG. 8, the hole 16d is replaced with gas hole 15c, so the gas hole ratio is 1.0.

[0056] When plasma processing was performed on the shower head 13 according to the embodiment shown in FIG. 7, the temperature of the upper electrode 14 was reduced by 15° C. compared to the shower head 13 according to the comparative example shown in FIG. 8.

[0057] As described above, the plasma processing apparatus 1 according to the embodiment includes a plasma processing chamber 10, a substrate support 11, and a shower head 13 (upper electrode assembly). Plasma is generated inside the plasma processing chamber 10. The substrate support 11 is provided within the plasma processing chamber 10 and supports a substrate W. The shower head 13 includes an upper electrode 14 disposed opposite the substrate support 11, and a cooling plate 15 provided on the upper electrode 14 and having gas diffusion chambers 16, 16a-16c formed therein for diffusing supplied gas. The upper electrode 14 has a plurality of gas holes 14c (first holes) formed therein. The cooling plate 15 has a plurality of gas holes 15c (second holes) formed in its lower surface 16ab-16cb, 16e (first surface) on the upper electrode 14 side of the gas diffusion chamber 16, which communicates with the plurality of gas holes 14c, and has holes 16ad, 16d (third holes) formed in its lower surface 16ab-16cb, 16e, which reach the upper electrode 14. This allows the plasma processing apparatus 1 to lower the temperature of the upper electrode 14.

[0058] The cooling plate 15 has an outlet 16ac for gas flow formed on an upper surface 16aa (second surface) facing the lower surface 16ab of the gas diffusion chamber 16a, and a hole 16ad formed on the lower surface 16ab in a portion facing the outlet 16ac. This allows the plasma processing apparatus 1 to further lower the temperature of the upper electrode 14.

[0059] Furthermore, in the cooling plate 15, the gas diffusion chamber 16 is formed in a disk shape, and the hole 16ad is formed in the center of the gas diffusion chamber 16. As a result, the shower head 13 according to the embodiment can lower the temperature of the center of the upper electrode 14, which tends to become hot.

[0060] Furthermore, the plurality of gas holes 14c are formed so that the diameter on the cooling plate 15 side is smaller than the diameter on the substrate support part 11 side. This allows the plasma processing apparatus 1 to further lower the temperature of the upper electrode 14.

[0061] 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.

[0062] 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.

[0063] In the above embodiment, the substrate processing is described as being performed on the substrate W by plasma processing such as plasma etching, but is not limited thereto. The substrate processing may be any type of substrate processing that is performed by evacuating the processing vessel and controlling the pressure within the processing vessel. For example, the substrate processing may be a film formation process, a modification process, or a heat treatment such as ashing.

[0064] Furthermore, the following supplementary notes are disclosed regarding the above-described embodiment.

[0065] (Supplementary Note 1) A plasma processing apparatus comprising: a chamber in which plasma is generated; a substrate support section provided in the chamber and supporting a substrate; an upper electrode arranged opposite the substrate support section; and an upper electrode assembly comprising: a cooling plate provided on the upper electrode and having a gas diffusion chamber formed therein for diffusing a supplied gas; wherein the upper electrode has a plurality of first holes formed therein; and the cooling plate has a first surface on the upper electrode side of the gas diffusion chamber formed therein, the second surface communicating with the plurality of first holes, and a third surface formed therein reaching the upper electrode.

[0066] (Supplementary Note 2) The plasma processing apparatus according to Supplementary Note 1, wherein the cooling plate has an outlet through which the gas flows out formed on a second surface opposite the first surface of the gas diffusion chamber, and the third hole is formed on a portion of the first surface opposite the outlet.

[0067] (Supplementary Note 3) The plasma processing apparatus according to Supplementary Note 1 or 2, wherein the gas diffusion chamber of the cooling plate is formed in a disk shape, and the third hole is formed in the center of the gas diffusion chamber.

[0068] (Supplementary Note 4) The plasma processing apparatus according to any one of Supplementary Notes 1 to 3, wherein the plurality of first holes are formed so that the diameter on the cooling plate side is smaller than the diameter on the substrate support part side.

[0069] 1 Plasma processing apparatus 10 Plasma processing chamber 10s Plasma processing space 11 Substrate support 12 Insulating member 13 Shower head 14 Upper electrode 14a Lower surface 14b, 16aa, 16aa-16ca Upper surface 14c, 15c Gas hole 15 Cooling plate 16, 16a-16c Gas diffusion chamber 16ab-16cb, 16e Lower surface 16ac-16cc Outlet 16ad, 16d Hole 17 Partition member 18a-18c Gas supply port 19a-19c Gas flow path 20 Gas supply unit 21 Gas source 22 Flow rate controller 23 Gas piping 30 Power supply 40 Exhaust system 111 Main body 112 Ring assembly 1110 Base 1111 Electrostatic chuck W substrate

Claims

1. A plasma processing apparatus comprising: a chamber in which plasma is generated; a substrate support section provided within the chamber and supporting a substrate; an upper electrode arranged opposite the substrate support section; and an upper electrode assembly comprising: a cooling plate provided on the upper electrode and having a gas diffusion chamber formed therein for diffusing a supplied gas; wherein the upper electrode has a plurality of first holes formed therein; and the cooling plate has a first surface on the upper electrode side of the gas diffusion chamber formed with a plurality of second holes communicating with the plurality of first holes, and a third hole formed in the first surface reaching the upper electrode.

2. The plasma processing apparatus according to claim 1, wherein the cooling plate has an outlet through which the gas flows out formed on a second surface opposite the first surface of the gas diffusion chamber, and the third hole is formed in a portion of the first surface opposite the outlet.

3. The plasma processing apparatus according to claim 1, wherein the gas diffusion chamber of the cooling plate is formed in a disk shape, and the third hole is formed in the center of the gas diffusion chamber.

4. The plasma processing apparatus according to claim 1, wherein the diameter of the plurality of first holes on the cooling plate side is smaller than the diameter on the substrate support part side.

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