Plasma Processing Equipment

Abstract

To provide a technique of uniformly generating plasma in a peripheral direction in a plasma generation space by using an electromagnetic wave introduced into a waveguide without using a coaxial line extended on a center axis line.SOLUTION: In a disclosed plasma processing apparatus, an upper shower head is provided above a substrate processing space in a chamber. A lower shower plate is provided below the upper shower head and above the substrate processing space. The lower shower plate and the upper shower head form a plasma generation space between them. An electromagnetic wave introduction part surrounds the plasma generation space. A waveguide surrounds the upper shower head and the electromagnetic wave introduction part, and is connected to the electromagnetic wave introduction part. The waveguide and the plasma generation space construct a resonator. A co-axial line is connected to the waveguide at a position separated from a center axial line.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] An exemplary embodiment of the present disclosure relates to a plasma processing apparatus. [Background technology]

[0002] Plasma processing apparatuses are used in the manufacture of electronic devices. One type of plasma processing apparatus is described in Patent Document 1. The plasma processing apparatus described in Patent Document 1 includes a processing vessel, a stage, an upper electrode, an introduction section, a waveguide section, a high-frequency power supply, a dielectric plate, and a gas supply section.

[0003] The stage is provided in the processing vessel. The upper electrode is provided above the space in the processing vessel. The introduction portion is a high-frequency introduction portion. The high-frequency wave is a VHF wave or a UHF wave. The introduction portion is provided at a lateral end of the space in the processing vessel and extends in a circumferential direction around the central axis of the processing vessel. The waveguide portion is configured to supply a high-frequency wave to the introduction portion. The waveguide portion includes a resonator providing a waveguide. The waveguide of the resonator extends in a circumferential direction around the central axis, extends in a direction in which the central axis extends, and is connected to the introduction portion. The waveguide portion further includes a first coaxial waveguide and a plurality of second coaxial waveguides. The high-frequency power source is connected to the waveguide of the resonator via the first coaxial waveguide and the plurality of second coaxial waveguides. The first coaxial waveguide extends on the central axis of the processing vessel, and the plurality of second coaxial waveguides extend in a radial direction from the first coaxial waveguide.

[0004] The dielectric plate is provided below the upper electrode to form a gap between the upper electrode and the dielectric plate. The dielectric plate constitutes a gas shower plate. The gas supply unit is connected to the gap provided between the upper electrode and the dielectric plate via a pipe. The pipe extends away from the central axis of the processing vessel. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2020-92031 A Summary of the Invention [Problem to be solved by the invention]

[0006] The present disclosure provides a technique for generating plasma uniformly in the circumferential direction within a plasma generation space by using electromagnetic waves introduced into a waveguide without using a coaxial line extending on a central axis. [Means for solving the problem]

[0007] In one exemplary embodiment, a plasma processing apparatus is provided. The plasma processing apparatus includes a chamber, an upper shower head, a lower shower plate, an electromagnetic wave introduction portion, a waveguide, and a coaxial line. The chamber provides a substrate processing space therein. The upper shower head is conductive, provides a plurality of gas holes, and is provided above the substrate processing space. The lower shower plate is conductive, provides a plurality of through holes connecting to the substrate processing space, and is provided below the upper shower head and above the substrate processing space. The lower shower plate forms a plasma generation space between the lower shower plate and the upper shower head, in which plasma of a gas supplied through the plurality of gas holes is generated. The electromagnetic wave introduction portion is made of a dielectric material, is provided between the upper shower head and the lower shower plate, and extends in a circumferential direction with respect to the central axis so as to surround the plasma generation space. The waveguide extends in a circumferential direction with respect to the central axis so as to surround the upper shower head and the electromagnetic wave introduction portion, and is connected to the electromagnetic wave introduction portion. The waveguide and the plasma generation space form a resonator. The coaxial line has a center conductor and an outer conductor and is configured to supply electromagnetic waves to the waveguide, the coaxial line extending away from the central axis, the center conductor being connected to a wall defining the waveguide at a location away from the central axis. Effect of the Invention

[0008] According to one exemplary embodiment, it is possible to generate plasma uniformly in the circumferential direction in a plasma generation space by using electromagnetic waves introduced into a waveguide without using a coaxial line extending on a central axis. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic diagram illustrating a plasma processing apparatus according to an exemplary embodiment; [Diagram 2] 1 is a partially cutaway view of a lower shower plate of a plasma processing apparatus according to an exemplary embodiment. [Diagram 3] FIG. 13 is a schematic diagram of a plasma processing apparatus according to another exemplary embodiment. [Figure 4] FIG. 13 is a schematic diagram of a plasma processing apparatus according to yet another exemplary embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Various exemplary embodiments are described below.

[0011] In one exemplary embodiment, a plasma processing apparatus is provided. The plasma processing apparatus includes a chamber, an upper shower head, a lower shower plate, an electromagnetic wave introduction portion, a waveguide, and a coaxial line. The chamber provides a substrate processing space therein. The upper shower head is conductive, provides a plurality of gas holes, and is provided above the substrate processing space. The lower shower plate is conductive, provides a plurality of through holes connecting to the substrate processing space, and is provided below the upper shower head and above the substrate processing space. The lower shower plate forms a plasma generation space between the lower shower plate and the upper shower head, in which plasma of a gas supplied through the plurality of gas holes is generated. The electromagnetic wave introduction portion is made of a dielectric material, is provided between the upper shower head and the lower shower plate, and extends in a circumferential direction with respect to the central axis so as to surround the plasma generation space. The waveguide extends in a circumferential direction with respect to the central axis so as to surround the upper shower head and the electromagnetic wave introduction portion, and is connected to the electromagnetic wave introduction portion. The waveguide and the plasma generation space form a resonator. The coaxial line has a center conductor and an outer conductor and is configured to supply electromagnetic waves to the waveguide, the coaxial line extending away from the central axis, the center conductor being connected to a wall defining the waveguide at a location away from the central axis.

[0012] In the above embodiment, the electromagnetic wave is introduced into the waveguide without using a coaxial line extending on the central axis. Furthermore, the waveguide and the plasma generation space form a resonator. Therefore, the wavelength of the electromagnetic wave propagating in the circumferential direction through the waveguide becomes infinite. As a result, a uniform electric field is generated in the circumferential direction within the resonator. Therefore, according to the above embodiment, it is possible to generate plasma uniformly in the circumferential direction within the plasma generation space.

[0013] In one exemplary embodiment, each of the plurality of through holes of the lower shower plate includes a lower portion on the side of the substrate processing space. The diameter of the lower portion of the through hole provided closer to the center of the lower shower plate than the other through holes among the plurality of through holes may be smaller than the diameter of the lower portion of the other through holes. In this embodiment, even if the density of the plasma in the plasma generating space decreases according to the distance from the central axis in the radial direction, the uniformity of the density of the radicals supplied to the substrate processing space is improved.

[0014] In one exemplary embodiment, the density of the through holes in the lower shower plate may increase with increasing distance from the center of the lower shower plate, which improves the uniformity of the density of the radicals supplied to the substrate processing space even if the plasma density in the plasma generating space decreases with the radial distance from the central axis.

[0015] In one exemplary embodiment, each of the plurality of through holes of the lower shower plate includes an upper portion on a side of the plasma generation space. The upper portion of each of the plurality of through holes may have a hollow cathode structure.

[0016] In one exemplary embodiment, the distance between the upper shower head and the lower shower plate may be 10 mm or less. In this embodiment, the distance between the upper shower head and the lower shower plate is smaller than the skin depth of the plasma. Therefore, the wavelength of the standing wave in the plasma generation space becomes longer. Therefore, the uniformity of the radial density of the plasma generated in the plasma generation space is increased. The distance between the upper shower head and the lower shower plate may be 5 mm or less.

[0017] In one exemplary embodiment, the plasma processing apparatus may further include a high frequency power source. The high frequency power source is configured to generate high frequency power having a variable frequency and is connected to the coaxial line. In this embodiment, the frequency of the high frequency power can be adjusted to maintain a resonant state of the electromagnetic wave in the resonator.

[0018] In one exemplary embodiment, the plasma processing apparatus may further include a first electric field antenna, a first detector, a second electric field antenna, a second detector, and a controller. The first electric field antenna is provided to receive the electromagnetic wave in a first region of the waveguide. The first detector is configured to output a first signal representing a first electric field intensity of the electromagnetic wave received by the first electric field antenna. The second electric field antenna is provided to receive the electromagnetic wave in a second region of the waveguide. The second detector is configured to output a second signal representing a second electric field intensity of the electromagnetic wave received by the second electric field antenna. The controller is configured to adjust the frequency of the high frequency power according to the first signal and the second signal so as to reduce the difference between the first electric field intensity and the second electric field intensity. The coaxial line is connected to introduce the electromagnetic wave from the first region to the waveguide. The direction in which the second region is located with respect to the central axis is opposite to the direction in which the first region is located with respect to the central axis. In this embodiment, it is possible to adjust the frequency of the high frequency power according to the first signal and the second signal so as to ensure uniformity of the electric field intensity along the circumferential direction in the waveguide.

[0019] In one exemplary embodiment, the plasma processing apparatus may further include a movable part configured to adjust the length of the waveguide to cause resonance of the electromagnetic wave in the resonator.

[0020] In one exemplary embodiment, the upper showerhead may include an upper shower plate and an upper wall. The upper shower plate provides the above-mentioned multiple gas holes. The upper wall is provided on the upper shower plate. The upper wall and the upper shower plate form a gas diffusion space therebetween that communicates with the multiple gas holes. The upper wall may provide a gas introduction port connected to the gas diffusion space on the central axis.

[0021] In one exemplary embodiment, the plasma processing apparatus may further include a source of cleaning gas connected to the gas inlet port via a pipe extending on the central axis.

[0022] In one exemplary embodiment, the plasma processing apparatus may further include a gas source of a deposition gas connected to the gas introduction port via the above-mentioned piping.

[0023] In one exemplary embodiment, the lower shower plate can have a ground potential.

[0024] In one exemplary embodiment, the wall surface to which the central conductor of the coaxial line is connected may be the side surface or the top surface of the upper showerhead.

[0025] Various exemplary embodiments will now be described in detail with reference to the drawings, in which the same or corresponding parts are designated by the same reference numerals.

[0026] Fig. 1 is a schematic diagram of a plasma processing apparatus according to an exemplary embodiment. The plasma processing apparatus 1 shown in Fig. 1 includes a chamber 10, a substrate support 12, an upper shower head 14, a lower shower plate 16, an electromagnetic wave introduction section 18, a waveguide 20, and a coaxial line 22.

[0027] The chamber 10 provides a substrate processing space 10s therein. The chamber 10 is made of a metal such as aluminum and is grounded. The chamber 10 may have a generally cylindrical shape with an opening at its upper end. The central axis of each of the chamber 10 and the substrate processing space 10s is an axis AX. The chamber 10 may have a corrosion-resistant film on its surface. The corrosion-resistant film may be a ceramic film containing an yttrium oxide film, an yttrium oxide fluoride film, an yttrium fluoride film, an yttrium oxide, or an yttrium fluoride film.

[0028] The bottom of the chamber 10 provides an exhaust port 10e. An exhaust system is connected to the exhaust port 10e. The exhaust system may include a vacuum pump, such as a dry pump and / or a turbomolecular pump, and an automatic pressure control valve.

[0029] The substrate support 12 is provided in the substrate processing space 10s. The substrate support 12 is configured to support the substrate W placed on its upper surface in an approximately horizontal manner. The substrate support 12 has an approximately disk shape. The central axis of the substrate support 12 is an axis AX.

[0030] The upper showerhead 14 is electrically conductive. The upper showerhead 14 is made of a metal such as aluminum. The upper showerhead 14 is provided above the substrate processing space 10s. The upper showerhead 14 provides a plurality of gas holes 14h. The diameter of the plurality of gas holes 14h may be about 0.3 mm.

[0031] In one embodiment, the upper shower head 14 may include an upper shower plate 24 and an upper wall 26. The upper shower plate 24 is electrically conductive. The upper shower plate 24 is made of a metal such as aluminum. The upper shower plate 24 has a substantially disk shape. The central axis of the upper shower plate 24 is an axis AX. The upper shower plate 24 provides a plurality of gas holes 14h. The plurality of gas holes 14h penetrate the upper shower plate 24 in the plate thickness direction.

[0032] The upper wall 26 is provided on the upper shower plate 24. The upper wall 26 is electrically conductive. The upper wall 26 is formed of a metal such as aluminum. The upper wall 26 has a substantially disk shape. The central axis of the upper wall 26 is the axis AX. The peripheral portion of the lower surface of the upper wall 26 is in contact with the upper shower plate 24. Therefore, the upper wall 26 is electrically connected to the upper shower plate 24. The lower surface of the upper wall 26 is separated from the upper shower plate 24 on the inner side of the peripheral portion. The position of the lower surface of the upper wall 26 in the height direction may be formed to become lower as the radial distance from the axis AX increases.

[0033] The upper wall 26 and the upper shower plate 24 form a gas diffusion space 14s therebetween. A plurality of gas holes 14h extend downward from the gas diffusion space 14s. The upper wall 26 provides a gas inlet port 14p. The gas inlet port 14p extends downward on the axis AX from the upper surface of the upper wall 26 and connects to the gas diffusion space 14s.

[0034] In an embodiment, the plasma processing apparatus 1 may further include a gas supply unit 28. The gas supply unit 28 may include a gas source 281 and a gas source 282. The gas source 281 is a source of a processing gas used in processing the substrate W. The processing gas may be a film forming gas. The gas source 282 is a source of a cleaning gas. The cleaning gas is used in cleaning the wall surface in the chamber 10. The gas source 281 and the gas source 282 are connected to the gas introduction port 14p via a pipe 30. The pipe 30 extends on the axis AX.

[0035] The lower shower plate 16 is provided below the upper shower head 14 and above the substrate processing space 10s. The lower shower plate 16 closes the upper end opening of the chamber 10. The peripheral portion of the lower shower plate 16 may be disposed on the top of the chamber 10.

[0036] The lower shower plate 16 is conductive. The lower shower plate 16 is made of a metal such as aluminum. The lower shower plate 16 is grounded and has a ground potential. The lower shower plate 16 has a substantially disk shape. The central axis of the lower shower plate 16 is an axis AX.

[0037] The lower shower plate 16 provides a plurality of through holes 16h. The plurality of through holes 16h penetrate the lower shower plate 16 in the plate thickness direction. The plurality of through holes 16h are connected to the substrate processing space 10s. The lower shower plate 16 and the upper shower plate 24 of the upper showerhead 14 form a plasma generation space 32 therebetween. The plasma generation space 32 is a space in which plasma of gas supplied through the plurality of gas holes 14h is generated.

[0038] In one embodiment, the distance between the upper shower plate 24 and the lower shower plate 16 of the upper showerhead 14, i.e., the vertical length of the plasma generation space 32, may be 10 mm or less. The distance between the upper shower plate 24 and the lower shower plate 16 of the upper showerhead 14 may be 5 mm or less.

[0039] The electromagnetic wave introduction part 18 is formed of a dielectric material such as quartz, aluminum nitride, or aluminum oxide. The electromagnetic wave introduction part 18 is provided between the upper shower plate 24 and the lower shower plate 16 of the upper shower head 14. The electromagnetic wave introduction part 18 surrounds the plasma generation space 32. The central axis of the electromagnetic wave introduction part 18 is the axis AX. The electromagnetic wave introduction part 18 extends in the circumferential direction about the axis AX. The electromagnetic wave introduction part 18 has a substantially ring shape. The electromagnetic wave introduction part 18 introduces the electromagnetic wave propagating from the waveguide 20 into the plasma generation space 32. The electromagnetic wave is a high frequency wave such as a VHF wave or a UHF wave, and is generated by a high frequency power source described later.

[0040] The waveguide 20 extends in the circumferential direction with respect to the axis AX so as to surround the upper showerhead 14 and the electromagnetic wave introduction part 18. The waveguide 20 has a substantially cylindrical shape. The waveguide 20 is connected to the electromagnetic wave introduction part 18. The waveguide 20 and the plasma generation space 32 form a resonator 34. The length of the waveguide 20 (the vertical length of the waveguide 20 in the plasma processing apparatus 1) is set so that the electromagnetic wave resonates in the resonator 34. That is, the length of the waveguide 20 is set so that the inductance when the waveguide 20 is seen from the electromagnetic wave introduction part 18 and the capacitance when the plasma generation space 32 is seen from the electromagnetic wave introduction part 18 cause the electromagnetic wave to resonate.

[0041] The waveguide 20 may be defined by an inner wall 20i, an outer wall 20o, and an upper wall 20t. The inner wall 20i, the outer wall 20o, and the upper wall 20t are formed of a conductor. The inner wall 20i, the outer wall 20o, and the upper wall 20t are formed of a metal such as aluminum. Each of the inner wall 20i and the outer wall 20o has a substantially cylindrical shape. The central axis of each of the inner wall 20i and the outer wall 20o is the axis AX. The inner wall 20i is provided inside the outer wall 20o. The lower end of the inner wall 20i is in contact with the upper surface of the peripheral portion of the upper wall 26 of the upper shower head 14. The lower end of the outer wall 20o is in contact with the upper surface of the peripheral portion of the lower shower plate 16. The upper wall 20t has a ring shape and closes an opening between the upper end of the inner wall 20i and the upper end of the outer wall 20o.

[0042] The coaxial line 22 has a center conductor 22i and an outer conductor 22o. The coaxial line 22 extends away from an axis AX. The coaxial line 22 is provided to supply electromagnetic waves to the waveguide 20. The coaxial line 22 is connected between a high frequency power source 36 and the waveguide 20. The high frequency power source 36 is a power source that generates high frequency power. In one embodiment, the high frequency power source 36 may be configured to generate high frequency power whose frequency is variable. The high frequency power generated by the high frequency power source 36 is supplied to the waveguide 20 as an electromagnetic wave via a matching device 38 through the coaxial line 22. The matching device 38 includes a matching circuit for matching the impedance of the load of the high frequency power source 36 to the output impedance of the high frequency power source 36.

[0043] The outer conductor 22o has a substantially cylindrical shape. The central conductor 22i is provided inside the outer conductor 22o. The central conductor 22i is provided coaxially with the outer conductor 22o. The coaxial line 22 extends from the outside of the waveguide 20, i.e., from the outside of the outer wall 20o toward the waveguide 20. An end of the outer conductor 22o is connected to the outer wall 20o. An end of the central conductor 22i is connected to a wall surface that defines the waveguide 20 at a position away from the axis AX. In the plasma processing apparatus 1, the central conductor 22i is connected to the upper shower head 14 at a position away from the axis AX. Specifically, an end of the central conductor 22i is connected to a side surface of the upper wall 26 of the upper shower head 14.

[0044] In the plasma processing apparatus 1, the electromagnetic wave is introduced into the waveguide 20 without using a coaxial line extending on the axis AX. The waveguide 20 and the plasma generation space 32 form a resonator 34. Therefore, the wavelength of the electromagnetic wave propagating in the circumferential direction through the waveguide 20 becomes infinite. As a result, a uniform electric field is generated in the circumferential direction in the resonator 34. Therefore, the plasma processing apparatus 1 can generate plasma uniformly in the circumferential direction in the plasma generation space 32.

[0045] In addition, in the plasma processing apparatus 1, the plasma generating space 32 is formed between the upper shower head 14 and the lower shower plate 16, so the volume of the plasma generating space 32 is small. Therefore, the electromagnetic wave is less likely to be absorbed in the plasma generating space 32, and the Q value of the resonator 34 is high. Therefore, even if the electromagnetic wave is introduced into the waveguide 20 from a single point away from the axis AX, a uniform electromagnetic field distribution in the circumferential direction can be obtained in the resonator 34, and plasma having a uniform density in the circumferential direction can be obtained.

[0046] As described above, the distance between the upper shower plate 24 and the lower shower plate 16 of the upper shower head 14, i.e., the vertical length of the plasma generation space 32, may be 10 mm or less. In this case, the distance between the upper shower head 14 and the lower shower plate 16 is smaller than the skin depth of the plasma. When the distance between the upper shower plate 24 and the lower shower plate 16 is smaller than the skin depth of the plasma, the electromagnetic wave propagates in the plasma generation space 32 in the TEM mode. On the other hand, when the distance between the upper shower head 14 and the lower shower plate 16 is sufficiently larger than the skin depth of the plasma, the electromagnetic wave propagates in the plasma generation space 32 in the surface wave mode. The wavelength of the electromagnetic wave in the TEM mode is longer than the wavelength of the electromagnetic wave in the surface wave mode. Therefore, in the plasma processing apparatus 1, the wavelength of the standing wave in the plasma generation space 32 becomes longer. Therefore, the uniformity of the density of the plasma generated in the plasma generation space 32 in the radial direction is increased. As described above, the distance between the upper shower plate 24 and the lower shower plate 16 of the upper showerhead 14 may be 5 mm or less.

[0047] Furthermore, in the plasma processing apparatus 1, the gas from the gas supply unit 28 can be supplied into the chamber 10 through the piping 30 extending on the axis line AX. This makes it possible to perform a uniform process on the substrate W. Furthermore, it becomes possible to perform uniform cleaning of the wall surface in the chamber 10.

[0048] In addition, since the lower shower plate 16 is grounded, the substrate processing space 10s is shielded from electromagnetic waves. Therefore, the influence of standing waves on the substrate processing space 10s side can be ignored, and the distance between the lower shower plate 16 and the substrate support 12 can be shortened. Furthermore, the lower shower plate 16 suppresses diffusion of plasma into the substrate processing space 10s. Therefore, the amount of ions incident on the substrate W and the energy of the ions incident on the substrate W can be suppressed, and good processing of the substrate W by radicals can be performed.

[0049] As described above, the high frequency power supply 36 may be configured to generate high frequency power whose frequency is variable. In this case, it is possible to maintain the resonant state of the electromagnetic wave in the resonator 34 by adjusting the frequency of the high frequency power.

[0050] Reference is now made to FIG. 2. FIG. 2 is a partially cutaway view of a lower shower plate of a plasma processing apparatus according to an exemplary embodiment. As shown in FIG. 2, each of the plurality of through holes 16h of the lower shower plate 16 may include a lower portion 16b on the side of the substrate processing space 10s and an upper portion 16u on the side of the plasma generating space 32. In each of the plurality of through holes 16h, the lower portion 16b is a portion that opens toward the substrate processing space 10s. In each of the plurality of through holes 16h, the upper portion 16u extends upward from the lower portion 16b and opens toward the plasma generating space 32.

[0051] The diameter of the lower portion 16b of the through hole 16h that is closer to the center of the lower shower plate 16 than the other through holes may be smaller than the diameter of the lower portion 16b of the other through holes. For example, the lower portion 16b of each of the through holes 16h may have a diameter that increases with increasing distance from the axis AX. In this case, even if the density of the plasma in the plasma generating space 32 decreases with the distance from the axis AX in the radial direction, the uniformity of the density of the radicals supplied to the substrate processing space 10s is improved.

[0052] In one embodiment, the upper portion 16u of each of the plurality of through holes 16h may have a hollow cathode structure. In order to generate hollow cathode plasma in the upper portion 16u of each of the plurality of through holes 16h, the product of the diameter of the upper portion 16u and the gas pressure may be about 1.5 mm·Torr. For example, when the gas pressure is 0.3 Torr, the diameter of the upper portion 16u of each of the plurality of through holes 16h may be 5 mm. In this way, when the upper portion 16u of each of the plurality of through holes 16h has a hollow cathode structure, active species required for the process are efficiently generated by high-density plasma.

[0053] Hereinafter, a plasma processing apparatus according to another exemplary embodiment will be described with reference to Fig. 3. Fig. 3 is a schematic diagram of a plasma processing apparatus according to another exemplary embodiment. Hereinafter, the plasma processing apparatus 1B will be described from the viewpoint of differences between the plasma processing apparatus 1B shown in Fig. 3 and the plasma processing apparatus 1.

[0054] In the plasma processing apparatus 1B, the waveguide 20 extends in the circumferential direction around the axis AX so as to surround the electromagnetic wave introducing part 18 and the upper shower head 14. The waveguide 20 is bent along the upper shower head 14, and its upper portion extends toward the axis AX. In the plasma processing apparatus 1B, the lower end of the inner wall 20i contacts the upper surface of the upper wall 26.

[0055] The plasma processing apparatus 1B may further include a first electric field antenna 41, a first wave detector 51, a second electric field antenna 42, a second wave detector 52, and a controller 56.

[0056] The first electric field antenna 41 is provided to receive the electromagnetic wave in the first region 201 of the waveguide 20. The coaxial line 22 is connected to introduce the electromagnetic wave from the first region 201 to the waveguide 20. The first electric field antenna 41 is provided in an opening formed in the upper wall 20t. The opening may be sealed with a resin such as polytetrafluoroethylene. The first electric field antenna 41 is connected to a first detector 51 via the coaxial line. The first detector 51 is configured to output a first signal. The first signal represents a first electric field intensity of the electromagnetic wave received by the first electric field antenna 41.

[0057] The second electric field antenna 42 is provided to receive the electromagnetic wave in the second region 202 of the waveguide 20. The direction in which the second region 202 is located with respect to the axis AX is opposite to the direction in which the first region 201 is located with respect to the axis AX. The second electric field antenna 42 is provided in an opening formed in the upper wall 20t. This opening may be sealed with a resin such as polytetrafluoroethylene. The second electric field antenna 42 is connected to the second detector 52 via a coaxial line. The second detector 52 is configured to output a second signal. The second signal represents a second electric field intensity of the electromagnetic wave received by the second electric field antenna 42.

[0058] The controller 56 is configured to adjust the frequency of the radio frequency power generated by the radio frequency power supply 36 in response to the first signal and the second signal so as to reduce the difference between the first electric field intensity and the second electric field intensity. In one embodiment, the controller 56 may be configured to adjust the frequency of the radio frequency power generated by the radio frequency power supply 36 in response to the signal generated by the differential amplifier 54. The differential amplifier 54 outputs a signal generated by amplifying the difference signal between the first signal and the second signal to the controller 56.

[0059] According to the plasma processing apparatus 1B, it is possible to adjust the frequency of the high-frequency power in response to the first signal and the second signal so as to ensure uniformity of the electric field intensity along the circumferential direction within the waveguide 20.

[0060] Hereinafter, a plasma processing apparatus according to still another exemplary embodiment will be described with reference to Fig. 4. Fig. 4 is a schematic diagram of a plasma processing apparatus according to still another exemplary embodiment. Hereinafter, the plasma processing apparatus 1C will be described from the viewpoint of differences between the plasma processing apparatus 1C shown in Fig. 4 and the plasma processing apparatus 1.

[0061] The plasma processing apparatus 1C further includes a movable part 60. The movable part 60 is formed of a conductor. The movable part 60 has a ring shape and extends in the circumferential direction inside the waveguide 20. The movable part 60 is configured to adjust the length of the waveguide 20 to cause resonance of the electromagnetic wave in the resonator 34. The movable part 60 may be connected to a driving device 64 via one or more shafts 62. The driving device 64 is configured to generate power for moving the movable part 60 up and down via the shafts 62.

[0062] Although various exemplary embodiments have been described above, the present invention is not limited to the above-described exemplary embodiments, and various additions, omissions, substitutions, and modifications may be made. In addition, elements in different embodiments can be combined to form other embodiments.

[0063] For example, in each of the plasma processing apparatuses 1 and 1C, the end of the central conductor 22i of the coaxial line 22 may be connected to the inner wall 20i. Also, in the plasma processing apparatus 1B, the end of the central conductor 22i of the coaxial line 22 may be connected to the upper surface of the upper wall 26 that defines the waveguide 20.

[0064] Furthermore, the density of the through holes 16h in the lower shower plate 16 may increase with increasing distance from the center of the lower shower plate 16. In this case, the diameters of the through holes 16h may be the same. In this case, even if the density of the plasma in the plasma generating space 32 decreases with increasing distance from the axis AX in the radial direction, the uniformity of the density of the radicals supplied to the substrate processing space 10s is improved.

[0065] Furthermore, each of the plasma processing apparatus 1 and the plasma processing apparatus 1C may include the first electric field antenna 41, the first detector 51, the second electric field antenna 42, the second detector 52, the differential amplifier 54, and the controller 56 described above.

[0066] From the foregoing, it will be understood that various embodiments of the present disclosure have been described herein for purposes of illustration, and that various modifications may be made without departing from the scope and spirit of the present disclosure. Accordingly, the various embodiments disclosed herein are not intended to be limiting, with the true scope and spirit being indicated by the appended claims. [Explanation of symbols]

[0067] Reference Signs List 1: plasma processing apparatus, 10: chamber, 10s: substrate processing space, 14: upper shower head, 16: lower shower plate, 18: electromagnetic wave introduction section, 20: waveguide, 22: coaxial line, 32: plasma generation space, 34: resonator.

Claims

1. a chamber providing a substrate processing space therein; an upper showerhead having electrical conductivity and providing a plurality of gas holes, the upper showerhead being disposed above the substrate processing space; a lower shower plate having electrical conductivity and providing a plurality of through holes connected to the substrate processing space, the lower shower plate being disposed below the upper showerhead and above the substrate processing space, the lower shower plate forming a plasma generation space between the lower shower plate and the upper showerhead, in which plasma of a gas supplied through the plurality of gas holes is generated; an electromagnetic wave introduction section that is made of a dielectric material and is provided between the upper shower head and the lower shower plate, and that extends in a circumferential direction about a central axis so as to surround the plasma generation space; a waveguide extending in the circumferential direction with respect to the central axis so as to surround the upper showerhead and the electromagnetic wave introducing part and connected to the electromagnetic wave introducing part, the waveguide and the plasma generation space constituting a resonator; a coaxial line having a center conductor and an outer conductor, the coaxial line being configured to supply electromagnetic waves to the waveguide, the coaxial line extending away from the center axis, the center conductor being connected to a wall defining the waveguide at a position away from the center axis; A plasma processing apparatus comprising:

2. each of the plurality of through holes includes a lower portion on a side of the substrate processing space; a diameter of the lower portion of a through hole provided closer to the center of the lower shower plate relative to other through holes among the plurality of through holes is smaller than a diameter of the lower portion of the other through holes; The plasma processing apparatus according to claim 1 .

3. The plasma processing apparatus of claim 1 , wherein a density of the plurality of through holes increases with increasing distance from a center of the lower shower plate.

4. Each of the plurality of through holes includes an upper portion on a side of the plasma generation space, The upper portion of each of the plurality of through holes has a hollow cathode structure. The plasma processing apparatus according to any one of claims 1 to 3.

5. 5. The plasma processing apparatus according to claim 1, wherein a distance between the upper shower head and the lower shower plate is 10 mm or less.

6. 5. The plasma processing apparatus according to claim 1, wherein a distance between the upper shower head and the lower shower plate is 5 mm or less.

7. 7. The plasma processing apparatus according to claim 1, further comprising a high frequency power source configured to generate high frequency power whose frequency is variable and connected to the coaxial line.

8. a first electric field antenna configured to receive electromagnetic waves at a first region of the waveguide; a first detector configured to output a first signal representative of a first electric field strength of an electromagnetic wave received by the first electric field antenna; a second electric field antenna configured to receive electromagnetic waves at a second region of the waveguide; a second detector configured to output a second signal representative of a second electric field strength of the electromagnetic wave received by the second electric field antenna; a controller configured to adjust the frequency of the radio frequency power in response to the first signal and the second signal to reduce a difference between the first electric field strength and the second electric field strength; Further comprising: the coaxial line is connected to introduce the electromagnetic wave from the first region to the waveguide; A direction in which the second region is located with respect to the central axis is opposite to a direction in which the first region is located with respect to the central axis. The plasma processing apparatus according to claim 7 .

9. 9. The plasma processing apparatus according to claim 1, further comprising a movable part configured to adjust a length of the waveguide to cause resonance of the electromagnetic wave in the resonator.

10. The upper shower head includes: an upper shower plate providing the plurality of gas holes; an upper wall provided on the upper shower plate; Including, the upper wall and the upper shower plate form a gas diffusion space therebetween that communicates with the plurality of gas holes, The upper wall provides a gas inlet port connected to the gas diffusion space on the central axis. The plasma processing apparatus according to any one of claims 1 to 9.

11. 11. The plasma processing apparatus according to claim 10, further comprising a gas source of a cleaning gas connected to the gas inlet port via a pipe extending on the central axis.

12. The plasma processing apparatus according to claim 11 , further comprising a gas source of a film forming gas connected to the gas inlet port via the piping.

13. 13. The plasma processing apparatus according to claim 1, wherein the lower shower plate has a ground potential.

14. 14. The plasma processing apparatus according to claim 1, wherein the wall surface to which the central conductor is connected is a side surface or an upper surface of the upper showerhead.

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