Plasma Processing Equipment

Abstract

To attain an improvement in uniformity of a plasma process.SOLUTION: A plasma processing apparatus 1 comprises: a processing container 10 including a substrate support part 18 thereinside; a shower head 20 which supplies active species of a first gas into the processing container; a first dissociation space 30b configured to supply the active species of the first gas to the shower head; and a resonator configured to supply electromagnetic waves of a VHF band or higher to the first dissociation space. The resonator includes: a cylindrical body 40 configuring a housing of the resonator; a gas pipe 22 which passes the inside of the cylindrical body, is provided along a central axis direction of the cylindrical body, includes a plurality of gas holes in an end portion and is configured to supply the first gas in a shower state through the plurality of gas holes to the first dissociation space; and a dielectric window 21 that allows an end of the gas pipe to penetrate in a central part, seals the gap between the gas pipe and the cylindrical body, and is configured to transmit the electromagnetic waves to the first dissociation space.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] Patent Document 1 proposes a plasma CVD apparatus having a plasma generation chamber sandwiched between a high-frequency application electrode and an intermediate mesh plate electrode for plasma separation, which are parallel to each other, and a counter electrode located outside the plasma generation chamber and on which a substrate is placed parallel to the intermediate mesh plate electrode. In Patent Document 1, the intermediate mesh plate electrode is movable in both directions, toward the counter electrode side and the high-frequency application electrode side, and a high frequency can be applied to the counter electrode.

[0003] Patent Document 2 proposes a plasma processing apparatus that introduces VHF waves and generates plasma from gas by the VHF waves. In Patent Document 2, an upper electrode and a lower electrode have recesses on their mutually facing surfaces, an upper dielectric and a lower dielectric are provided in the recesses of the upper electrode and the lower electrode, respectively, and an introduction portion for the VHF waves is provided at the lateral end of the space between the upper dielectric and the lower dielectric.

[0004] Patent Document 3 proposes a plasma processing apparatus that introduces microwaves and generates plasma from a gas by the microwaves. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 11-162957 [Patent Document 2] JP 2020-92033 A [Patent Document 3] Japanese Patent Application Publication No. 11-204295 Summary of the Invention [Problem to be solved by the invention]

[0006] The present disclosure provides a technique that can improve the uniformity of a plasma process. [Means for solving the problem]

[0007] According to one aspect of the present disclosure, there is provided a plasma processing apparatus including: a processing vessel having a substrate support therein; a showerhead that supplies activated species of a first gas into the processing vessel; a first dissociation space configured to supply the activated species of the first gas to the showerhead; and a resonator configured to supply electromagnetic waves in the VHF band or higher to the first dissociation space, wherein the resonator includes a cylindrical body that constitutes a housing of the resonator; a gas pipe that passes through the inside of the cylindrical body and is arranged along a central axial direction of the cylindrical body, the gas pipe having a plurality of gas holes at an end thereof and configured to supply the first dissociation space in a shower-like manner via the plurality of gas holes; and a dielectric window through which an end of the gas pipe passes at a center portion, sealing a space between the gas pipe and the cylindrical body, and configured to transmit the electromagnetic waves to the first dissociation space. Effect of the Invention

[0008] According to one aspect, the uniformity of the plasma process can be improved. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic cross-sectional view showing an example of a plasma processing apparatus according to an embodiment; [Diagram 2] FIG. 2 is a schematic cross-sectional view showing an example of a resonator unit according to the embodiment. [Diagram 3] FIG. 2 is a cross-sectional view taken along line AA in FIG. 1. [Figure 4] FIG. 4 is a diagram showing an example of plasma density. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and duplicated descriptions may be omitted.

[0011] [Plasma processing equipment] Hereinafter, the plasma processing apparatus according to the embodiment will be described in detail with reference to the drawings. One way to improve the performance of the plasma processing apparatus is to increase the frequency. In this case, it is possible to use electromagnetic waves in the VHF band or higher, which are higher than the frequency of a general high frequency (for example, 13.56 MHz). For example, the frequency of electromagnetic waves in the VHF band is 30 MHz to 300 MHz, and the frequency of electromagnetic waves in the UHF band is 300 MHz to 3 GHz. Since electromagnetic waves in the VHF band and UHF band have higher frequencies than general high frequencies, dissociation of gases that are difficult to dissociate with normal high frequencies can be controlled to be highly dissociated, and the performance of the plasma processing apparatus 1 can be improved. However, when electromagnetic waves in the VHF band and UHF band are applied to the inside of the chamber, the wavelengths of these electromagnetic waves are shorter than those of normal high frequencies, which may result in poor plasma uniformity and non-uniform processes such as film formation and etching.

[0012] In the plasma processing apparatus described below, as shown in FIG. 1, a first dissociation space 30b is provided in the gas activation unit 2 in addition to the second dissociation space 30e, which is a process space in the chamber 10. The first dissociation space 30b and the second dissociation space 30e are both plasma generation spaces. As a result, the first gas supplied to the first dissociation space 30b is dissociated using electromagnetic waves in the VHF band or higher, the activated species of the first gas are supplied into the chamber 10, and the activated species of the first gas are further turned into plasma in the second dissociation space 30e. As a result, even when electromagnetic waves in the VHF band and UHF band are used, the use of the gas activation unit 2 can ensure uniformity of the plasma. The chamber 10 is an example of a processing vessel.

[0013] A plasma processing apparatus 1 according to an embodiment will be described with reference to Fig. 1 to Fig. 3. Fig. 1 is a schematic cross-sectional view showing an example of a plasma processing apparatus according to an embodiment. Fig. 2 is a schematic cross-sectional view showing an example of a resonator unit according to an embodiment. Fig. 3 is a cross-sectional view taken along line AA in Fig. 1.

[0014] The plasma processing apparatus 1 shown in FIG. 1 includes a chamber 10 and a gas activation unit 2. The plasma processing apparatus 1 is configured to generate plasma from gas in the gas activation unit 2 by electromagnetic waves in the VHF band or higher. The plasma processing apparatus 1 is also configured to generate plasma from gas in the chamber 10 by high-frequency waves having a lower frequency than the frequencies of the electromagnetic waves in the VHF band or higher. The electromagnetic waves may be in the VHF band or higher, but are preferably in the UHF band or higher, and the upper limit of the electromagnetic waves may be the same as the upper limit of the UHF band. The chamber 10 has an axis AX as its central axis. The axis AX is an axis extending in the vertical direction. A substrate W is processed in the chamber 10.

[0015] In one embodiment, the chamber 10 may include a chamber body 12. The chamber body 12 has a cylindrical shape and provides side and bottom walls of the chamber 10, and is open at the top. The chamber body 12 is formed from a metal, such as aluminum. The chamber body 12 is grounded.

[0016] The sidewall of the chamber body 12 provides a passage 12p. The substrate W passes through the passage 12p when being transferred between the inside and the outside of the chamber 10. The passage 12p can be opened and closed by a gate valve 12v. The gate valve 12v is provided along the sidewall of the chamber body 12.

[0017] The chamber 10 may further include an upper wall 14. The upper wall 14 is made of a metal such as aluminum. The upper wall 14 is disk-shaped and closes an opening at the top of the chamber body 12. The upper wall 14 and the chamber body 12 are grounded.

[0018] The bottom wall of the chamber 10 provides an exhaust port 16a. The exhaust port 16a is connected to an exhaust system 16. The exhaust system 16 includes a pressure controller, such as an automatic pressure control valve, and a vacuum pump, such as a turbomolecular pump.

[0019] The plasma processing apparatus 1 further includes a substrate support 18. The substrate support 18 is provided in the chamber 10. The substrate support 18 is configured to support a substrate W placed thereon. The substrate W is placed on the substrate support 18 in a substantially horizontal state. The substrate support 18 may be supported by a support member 19. The support member 19 extends upward from the bottom of the chamber 10. The substrate support 18 and the support member 19 may be formed from a dielectric material such as aluminum nitride.

[0020] The plasma processing apparatus 1 further includes a showerhead 20. The showerhead 20 is made of a metal such as aluminum. The showerhead 20 has a substantially disk shape and a hollow structure. The showerhead 20 shares an axis AX as its central axis. The showerhead 20 is provided above the substrate support 18 and below the upper wall 14. The showerhead 20 constitutes a ceiling portion that defines the internal space of the chamber 10, and the upper wall 14 is provided above the upper portion of the showerhead 20.

[0021] The showerhead 20 provides a diffusion chamber 30d therein. A plurality of gas holes 20i are formed in the showerhead 20, which penetrate vertically from the diffusion chamber 30d. The plurality of gas holes 20i open to the lower surface of the showerhead 20 and introduce gas toward a second dissociation space 30e between the showerhead 20 and the substrate support 18 in the chamber 10.

[0022] As a result, the shower head 20 introduces activated species of a first gas, which will be described later, from the diffusion chamber 30d through the multiple gas holes 20i into the second dissociation space 30e. The shower head 20 also introduces a second gas, which will be described later, from the diffusion chamber 30d through the multiple gas holes 20i into the second dissociation space 30e.

[0023] It is preferable that the diameter of each gas hole 20i of the shower head 20 is about 1 mm. If the diameter is less than 1 mm, the frequency of collisions between activated species of the first gas in the gas hole 20i increases. On the other hand, by setting the diameter of each gas hole 20i to about 1 mm, it is possible to reduce the probability that the activated species of the first gas return to the first gas before reaching the second dissociation space 30e.

[0024] The periphery of the showerhead 20 is covered with a dielectric member 33 such as ceramics. The periphery of the substrate support 18 is covered with a dielectric member 34 such as ceramics. If no high frequency is applied to the showerhead 20, the dielectric member 33 does not have to be provided. However, it is preferable to provide the dielectric member 33 in order to define the area of ​​the showerhead 20 that functions as a counter electrode for the substrate support 18. It is also preferable to provide the dielectric member 33 in order to make the ratio of anodes and cathodes of the electrodes as equal as possible.

[0025] A high frequency power supply 60 is connected to the substrate support 18 via a matching device 61. The matching device 61 has an impedance matching circuit. The impedance matching circuit is configured to match the impedance of the load of the high frequency power supply 60 to the output impedance of the high frequency power supply 60. The frequency of the high frequency supplied from the high frequency power supply 60 is lower than the frequency of the VHF wave supplied from the power supply 50, and is a frequency of 60 MHz or less. An example of the high frequency frequency is 13.56 MHz. The high frequency power supply 60 may apply a high frequency to the shower head 20.

[0026] The control unit (control device) 90 may be a computer having a processor 91 and a memory 92. The control unit 90 includes an arithmetic unit, a storage unit, an input device, a display device, a signal input / output interface, and the like. The control unit 90 controls each unit of the plasma processing device 1 including the gas activation unit 2. In the control unit 90, an operator can use the input device to input commands and the like to manage the plasma processing device 1. In addition, the control unit 90 can visualize and display the operating status of the plasma processing device 1 using the display device. Furthermore, the memory 92 of the control unit 90 stores a control program and recipe data. The control program is executed by the processor 91 of the control unit 90 to execute various processes in the plasma processing device 1. The processor 91 executes the control program and controls each unit of the plasma processing device 1 according to the recipe data, whereby various processes, for example, a plasma processing method, are executed in the plasma processing device 1.

[0027] The gas activation section 2 includes a resonator 100 and a first dissociation space 30b.

[0028] (Resonator: cylindrical body) The resonator 100 has a cylindrical body 40 that constitutes the housing of the resonator 100. The cylindrical body 40 is made of a metal such as aluminum and has a hollow structure. The cylindrical body 40 shares an axis AX as its central axis. The lower end of the gas activation unit 2 is fixed to an insulating member 35 on the upper wall 14 of the chamber 10. The insulating member 35 is made of ceramics such as aluminum nitride and has a hollow structure. It is inserted into a hole formed in the center of the upper wall 14, abuts against the upper surface around a through hole that penetrates the upper center of the shower head 20, and communicates with the diffusion chamber 30d. This insulates the gas activation unit 2 from the chamber 10.

[0029] The upper end of the cylindrical body 40 is closed by a disk-shaped cover conductor 44 having the same diameter as the outer diameter of the cylindrical body 40. The cover conductor 44 is made of a metal such as aluminum.

[0030] (Resonator: Gas piping) The resonator 100 further includes a gas pipe 22. The gas pipe 22 is a cylindrical tube. The gas pipe 22 passes through the inside of the cylindrical body 40, is provided along the central axis of the cylindrical body 40, and has a plurality of gas holes 23a at the end. The gas pipe 22 has a vertical portion 22a and a flange portion 22f. The vertical portion 22a and the flange portion 22f are formed of a metal such as aluminum. The vertical portion 22a penetrates the cover conductor 44 and is disposed in the center of the resonator 100. In other words, the vertical portion 22a and the cylindrical body 40 share an axis AX as the central axis of both, and are disposed so that the vertical portion 22a is wrapped by the cylindrical body 40. 2 and 3, which is a cross-sectional view taken along line AA in FIG. 1, flange portion 22f is a flange-shaped annular member provided perpendicularly to vertical portion 22a around the side surface of vertical portion 22a at the same height as inner conductor 36a of electromagnetic wave supply path 36. Supply path 36 has inner conductor 36a and outer conductor 36b. Outer conductor 36b of supply path 36 is connected to the side wall of cylindrical body 40. Inner conductor 36a is connected to flange portion 22f.

[0031] 1 to 3, the end of gas pipe 22 (vertical portion 22a) constitutes a small showerhead 23 having multiple gas holes 23a. Small showerhead 23 is configured to supply a first gas in a shower-like manner to first dissociation space 30b via the multiple gas holes 23a. In Fig. 3, gas hole 23a is arranged at equal intervals, with one in the center and six on the periphery, but the number and arrangement of gas holes 23a are not limited to this.

[0032] Since the wavelength of the surface wave of the UHF wave in the plasma is about 4 mm to 10 mm, the diameter of the plurality of gas holes 23a is 1 / 16 or less of the effective wavelength λg, for example, 0.6 mm or less. This makes it possible to prevent the plasma formed in the first dissociation space 30b from returning from the gas holes 23a to the inside of the gas piping 22, thereby preventing unnecessary energy consumption.

[0033] 1 is provided opposite a gas inlet 33a at the center of the upper part of the showerhead 20. The gas inlet 33a is connected to a diffusion chamber 30d.

[0034] (Gas source) In the embodiment, the plasma processing apparatus 1 has an N2 gas source 24a, an NF3 gas source 24b, and a SiH4 gas source 25. The N2 gas source 24a is connected to the upper part of the gas pipe 22. The N2 gas source 24a is a gas source of a reducing gas. The N2 gas is an example of a first gas. The NF3 gas source 24b is connected to the upper part of the gas pipe 22. The NF3 gas source 24b is a gas source of a cleaning gas. The cleaning gas is an example of a first gas. The cleaning gas may contain a halogen-containing gas. The halogen-containing gas contains, for example, NF3 and / or Cl2. In the present embodiment, the cleaning gas is NF3 gas, but may further contain other gases. The cleaning gas may further contain a rare gas such as Ar. The N2 gas source 24a is connected to the gas pipe 22 via a valve 29a. The NF3 gas source 24b is connected to the gas pipe 22 via a valve 29b.

[0035] The SiH4 gas source 25 is a gas source of a process gas such as a film-forming gas that directly supplies the second gas to the first dissociation space 30b. The side gas pipe 28 penetrates the side wall of the cylindrical body 40. The SiH4 gas source 25 supplies the second gas to the first dissociation space 30b from the gas hole 28a provided in the side wall of the cylindrical body 40 via the side gas pipe 28. SiH4 gas is an example of the second gas. When the second gas is a film-forming gas, it may contain a silicon-containing gas. The silicon-containing gas may further contain other gases in addition to, for example, silane gas (SiH4). For example, the film-forming gas may further contain a rare gas such as NH3 gas, N2 gas, or Ar. The film-forming gas such as SiH4 gas is a gas that should not be dissociated excessively. Therefore, the second gas may be directly supplied to the shower head 20. On the other hand, the first gas, such as reducing gas (N2 gas) or NF3 gas, is a gas that is desired to be sufficiently dissociated in the first dissociation space 30b so that the activated species of the first gas are supplied into the chamber 10. Therefore, the first gas is supplied from the upper part of the gas pipe 22 through the gas flow path 29 and the small shower head 23 to the first dissociation space 30b. This allows the first gas to be highly dissociated. The reason for this will be described later.

[0036] (1st dissociation space) Usually, in a vacuum space, in order to prevent the formation of electromagnetic wave nodes in the radial direction of the cylindrical body 40, the diameter R of the inner wall of the cylindrical body 40 must be set to 1 / 2 or less of the effective wavelength λg of the surface wave of the electromagnetic wave in a vacuum. In contrast, the effective wavelength of electromagnetic waves (VHF waves, UHF waves) is reduced to about 1 / 3 of λg in plasma. Since the first dissociation space 30b is a plasma generation space, in order to prevent the formation of electromagnetic wave nodes in the radial direction in the first dissociation space 30b, the diameter R of the inner wall of the cylindrical body 40 is set to 1 / 3 of (λg / 2), that is, smaller than λg / 6. This allows the energy of the electromagnetic wave to be efficiently transmitted while eliminating the effects of antinodes or nodes.

[0037] In the first dissociation space 30b, plasma of the first gas is generated by the electric field of the electromagnetic wave. During film formation, N2 gas and SiH4 gas are supplied to the first dissociation space 30b. The N2 gas is decomposed by the high electric field energy of the electromagnetic wave directly under the small shower head 23, and plasma of the first gas is generated. The SiH4 gas is directly supplied to the region of the first dissociation space 30b where the electric field energy of the electromagnetic wave is low. This makes it possible to suppress dissociation of the gas compared to N2 gas. During film formation, the valve 29b is closed and the valve 29a is opened to supply the N2 gas, which is a reducing gas, to the gas pipe 22, and the second gas is directly supplied to the first dissociation space 30b. During cleaning, the valve 29a is closed and the valve 29b is opened to supply the NF3 gas, which is a cleaning gas, to the gas pipe 22. During cleaning, the second gas is not supplied.

[0038] (Resonator: Dielectric window) The resonator 100 further has a dielectric window 21 made of ceramics or the like. The dielectric window 21 is annular with a hole in the center, through which the end of the gas pipe 22 passes. The inner circumference of the dielectric window 21 is adjacent to the side wall of the end of the gas pipe 22, and the outer circumference is adjacent to the inner wall of the cylindrical body 40. Thus, the dielectric window 21 is configured to seal the gap between the gas pipe 22 and the cylindrical body 40, to separate the resonator 100 from the first dissociation space 30b, and to transmit electromagnetic waves into the first dissociation space 30b.

[0039] A seal member 38 such as an O-ring is provided on the side wall of the gas pipe 22 on the inside of the upper surface of the dielectric window 21, and a seal member 39 such as an O-ring is provided on the side wall of the cylindrical body 40 on the outside of the lower surface of the dielectric window 21. This seals the first dissociation space 30b, which is a vacuum space, from the space 26 in the resonator 100, which is the atmospheric space, and keeps the first dissociation space 30b, which is a vacuum space, airtight.

[0040] (Resonator: internal structure and power supply connection structure) The base end of the supply path 36 of the resonator 100 is connected to the power source 50 via a matching device 41. The power source 50 is an electromagnetic wave generator and is configured to supply electromagnetic waves in the VHF band or higher. The matching device 41 has an impedance matching circuit. The impedance matching circuit is configured to match the impedance of the load of the power source 50 to the output impedance of the power source 50. The impedance matching circuit has a variable impedance. The impedance matching circuit is, for example, a π-type circuit. The electromagnetic waves introduced from the electromagnetic wave supply path 36 to the gas activation section 2 resonate in the resonator 100 and are supplied to the first dissociation space 30b below the resonator 100 with high energy efficiency.

[0041] A dielectric 31 is embedded in at least a part of the inside of the resonator 100. In this embodiment, the inside of the resonator 100 is filled with the dielectric 31 except for the space 26 in the resonator 100. Specifically, the dielectric 31 is filled from just below the cover conductor 44 at the top of the resonator 100 to the flange portion 22f, and between the inner conductor 36a and the outer conductor 36b of the electromagnetic wave supply path 36. The dielectric 31 is provided to shorten the wavelength of the electromagnetic wave. The resonator 100 is configured to supply electromagnetic waves in the VHF band or higher to the first dissociation space. The dielectric 31 is, for example, polytetrafluoroethylene (PTFE: Poly Tetra Fluoro Ethylene).

[0042] The lower end of the dielectric 31 may be located at the same position as the lower surface of the flange portion 22f in the vertical direction. In addition, the space 26 may also be filled with the dielectric 31.

[0043] [Gas activation section details] The configuration of the gas activation section 2 will be further described with reference to Fig. 2 and Fig. 3 in addition to Fig. 1. A dielectric window 21 is provided below the flange section 22f to separate the resonator 100 from the first dissociation space 30b. Below the dielectric window 21 is the first dissociation space 30b. The space above the dielectric window 21 is at atmospheric pressure, and the space below the dielectric window 21 is at vacuum pressure. In other words, the inside of the resonator 100 is at atmospheric pressure, and the inside of the first dissociation space 30b is at vacuum pressure.

[0044] The first dissociation space 30b has a cylindrical cross-sectional shape, and has a diameter substantially equal to the inner diameter of the resonator 100.

[0045] 2, electromagnetic waves (for example, UHF waves of 500 MHz) propagate from supply line 36 through resonator 100. The propagating electromagnetic waves resonate within resonator 100, transmit through dielectric window 21, and propagate to first dissociation space 30b, where they function as energy that dissociates the gas immediately below dielectric window 21, generating plasma of the gas supplied to first dissociation space 30b.

[0046] The electric field E is shown in Fig. 2. The cylindrical body 40 is configured so that the electric field E of the electromagnetic wave is minimum (0 [V]) at the bottom surface of the cover conductor 44 in the resonator 100 and maximum (Max [V]) at the top surface of the dielectric window 21. In other words, the electromagnetic wave becomes a node at the bottom surface of the cover conductor 44 and becomes an antinode at the top surface of the dielectric window 21. In this way, maximizing the electric field at the top surface of the dielectric window 21 improves the plasma ignition ability inside the first dissociation space 30b and creates a state in which energy efficiency is high.

[0047] That is, since the electric field E is maximized on the upper surface of the dielectric window 21, the electromagnetic wave resonating in the resonator 100 is supplied to the first dissociation space 30b with high energy efficiency. The small showerhead 23 is formed in a shower shape at the tip of the center of the gas pipe 22, and is configured to be able to generate plasma P with high electron density at the outlet of the gas hole 23a of the small showerhead 23. The first gas is made into plasma in the central region of the first dissociation space 30b below the small showerhead 23, thereby generating plasma P of the first gas in a highly dissociated state in the first dissociation space 30b.

[0048] The plasma tends to become non-uniform when electromagnetic waves with a short wavelength are directly supplied to the shower head 20 and the gas is dissociated within the shower head 20. In contrast, in this embodiment, the first dissociation space 30b is used as a plasma generation space, surface wave plasma is generated in the first dissociation space 30b, and the first gas is highly dissociated by the electric field of the electromagnetic waves.

[0049] According to this, first dissociation space 30b functions as a plasma generation space, and the first gas is dissociated efficiently and sufficiently before being supplied to shower head 20, and then activated species of the first gas are introduced into shower head 20.

[0050] The second dissociation space 30e is a process space in which the first gas highly dissociated in the first dissociation space 30b and the second gas less dissociated (or not dissociated) are joined together to generate plasma of these gases. In the second dissociation space 30e, the first gas and the second gas are dissociated by high frequency waves supplied from the high frequency power supply 60.

[0051] Fig. 4 is a diagram showing an example of plasma electron density. The horizontal axis of Fig. 4 indicates the radius (distance) from the center of the dielectric window, with the center being set as 0, and the vertical axis indicates the plasma electron density generated in first dissociation space 30b. The power of the electromagnetic wave supplied to first dissociation space 30b is set to 100W, 200W, and 400W.

[0052] Fig. 4(a) shows the plasma electron density (Ne) generated below the dielectric window 21 when the shape of the dielectric window 21 according to this embodiment is annular and gas is supplied from the center. Fig. 4(b) shows the plasma electron density (Ne) generated below the dielectric window when the shape of the dielectric window according to the reference example is disk-shaped.

[0053] In the case of the ring-shaped dielectric window 21, a plasma sheath is also formed in the metal part of the lower surface (the surface where the gas holes 23a open) of the small shower head 23 arranged in the center. This allows surface waves of electromagnetic waves to propagate within the plasma sheath of the metal part. In this state, electromagnetic waves are concentrated from the dielectric windows 21 arranged around the periphery to the lower surface of the small shower head 23 in the center. As a result, energy is concentrated in the center of the ring-shaped dielectric window 21, and the electric field becomes strong.

[0054] As a result, when plasma is generated below the ring-shaped dielectric window 21, the plasma electron density (Ne) is highest at the center of the dielectric window 21, as shown in Fig. 4(a). On the other hand, when plasma is generated below a disk-shaped dielectric window, the energy is dispersed over the entire surface of the dielectric window. For this reason, as shown in Fig. 4(b), the plasma electron density at the center of the dielectric window is lower than in the present embodiment shown in Fig. 4(a), and the top of the plasma electron density becomes flat.

[0055] Therefore, according to the shape of the dielectric window 21 in this embodiment, the first gas can be caused to flow from the small shower head 23 to the center of the first dissociation space 30b, and the gas can be turned into plasma in the center where energy is high, thereby efficiently dissociating the first gas to a high degree.

[0056] Returning to Fig. 2, the surface (lower surface) of the dielectric window 21 exposed to the first dissociation space 30b has an annular recess 21a. By reducing the thickness of the dielectric window 21, it becomes difficult for the electromagnetic waves to pass through the recess 21a. This makes it possible to strengthen the electric field when the surface waves of the electromagnetic waves pass through the sheath of the metal part of the small showerhead 23, and to generate plasma with a higher plasma density. However, the recess 21a may not be provided on the lower surface of the dielectric window 21, and the shape of the lower surface may be made flat.

[0057] In order to prevent an electric field from being transmitted to the metal portion of the side surface of the small showerhead 23, the side surface 21b of the recess 21a is provided along the small showerhead 23 up to the end of the small showerhead 23 so as to protect the side wall of the small showerhead 23. The side surface 21c of the recess 21a is provided along the protrusion 40a of the cylindrical body 40 up to the end of the protrusion 40a so as to protect the protrusion 40a of the cylindrical body 40.

[0058] In the plasma processing apparatus 1 described above, a first dissociation space 30b is provided as a plasma generation space upstream of the shower head 20. The first gas is dissociated in the first dissociation space 30b, and the generated active species of gas, such as radicals, are supplied to the second dissociation space 30e through the shower head 20. The first gas that reaches the second dissociation space 30e is in a recombination excited state, and can be easily redissociated by high-frequency energy having a lower frequency than electromagnetic waves in the VHF band or higher. This makes it possible to improve the uniformity of the plasma process by utilizing the highly efficient radical generation ability, which is a characteristic of electromagnetic waves in the VHF band or higher, while avoiding non-uniformity in the plasma process due to the short wavelength of electromagnetic waves in the VHF band or higher.

[0059] As described above, according to the plasma processing apparatus of this embodiment, it is possible to improve the uniformity of the plasma process.

[0060] The plasma processing apparatus according to the embodiments disclosed herein should be considered as illustrative and not restrictive in all respects. The embodiments can be modified and improved in various ways without departing from the scope and spirit of the appended claims. The matters described in the above embodiments can be configured in other ways as long as they are not inconsistent, and can be combined as long as they are not inconsistent. [Explanation of symbols]

[0061] 1...Plasma processing device 2…Gas activation section 10. Chamber 18...Substrate support part 20…Shower head 21...Dielectric window 22...Gas piping 23. Small shower head 30b…first dissociation space 30d…Diffusion chamber 30e…Second dissociation space 40...Cylindrical body 100...Resonator

Claims

1. a processing vessel having a substrate support therein; a shower head for supplying activated species of a first gas into the processing vessel; a first dissociation space configured to supply activated species of the first gas to the showerhead; a resonator configured to supply electromagnetic waves of VHF or higher to the first dissociation space, The resonator comprises: A cylindrical body constituting a housing of the resonator; a gas pipe that passes through the inside of the cylindrical body, is provided along a central axis direction of the cylindrical body, has a plurality of gas holes at an end thereof, and is configured to supply the first gas in a shower-like manner to the first dissociation space via the plurality of gas holes; a dielectric window configured to pass through an end of the gas pipe at a central portion, seal the space between the gas pipe and the cylindrical body, and transmit the electromagnetic wave to the first dissociation space.

2. The electromagnetic waves are in the UHF band or higher. The plasma processing apparatus according to claim 1 .

3. applying a high frequency to at least one of the shower head and the substrate support to generate plasma of a gas containing activated species of the first gas supplied into the processing chamber; 3. The plasma processing apparatus according to claim 1 or 2.

4. a surface of the dielectric window exposed to the first dissociation space has an annular recess; The plasma processing apparatus according to any one of claims 1 to 3.

5. The first dissociation space is cylindrical, and the diameter of the first dissociation space is smaller than 1 / 6 of the wavelength λg of the surface wave of the electromagnetic wave. The plasma processing apparatus according to any one of claims 1 to 4.

6. The diameter of the plurality of gas holes is 1 / 16 or less of the wavelength λg of the surface wave of the electromagnetic wave. The plasma processing apparatus according to any one of claims 1 to 5.

7. The gas pipe passes through the resonator. The plasma processing apparatus according to any one of claims 1 to 6.

8. a side gas pipe provided in the cylindrical body and supplying a second gas from a side wall of the side gas pipe to the first dissociation space; The plasma processing apparatus according to any one of claims 1 to 7.

9. The inside of the resonator is at atmospheric pressure, and the first dissociation space is at vacuum pressure. The plasma processing apparatus according to any one of claims 1 to 8.

10. The first dissociation space is provided between the resonator and the shower head and is a space for generating plasma. The plasma processing apparatus according to any one of claims 1 to 9.

11. At least a portion of the resonator is embedded with a dielectric. The plasma processing apparatus according to any one of claims 1 to 10.

12. A node of the electric field of the electromagnetic wave is located at an upper end of the resonator, so that the electric field of the electromagnetic wave at the upper end of the resonator is minimized, and the gas pipe for supplying the first gas passes through the upper end of the resonator. The plasma processing apparatus according to any one of claims 1 to 11.

13. A configuration in which an antinode of the electric field of the electromagnetic wave is located on an upper surface of the dielectric window, so that the electric field of the electromagnetic wave on the upper surface of the dielectric window is maximized. The plasma processing apparatus according to any one of claims 1 to 12.

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