Substrate processing method and substrate processing apparatus

Abstract

To efficiently irradiate a substrate with electrons.SOLUTION: In one exemplary embodiment, there is provided a substrate processing method for processing a substrate supported by a substrate support in a processing container defining an internal space including a first space and a second space. The substrate processing method includes generating plasma of a first gas in a first space, applying a potential lower than a potential of a substrate support to a mesh member disposed between the first space and a second space and having a plurality of through-holes through which electrons in the plasma generated in the first space are selectively transmitted to the second space, and irradiating a substrate disposed in the second space with the electrons transmitted through the mesh member, and removing negative charges charged on the substrate by irradiating the substrate with the electrons by exposing the substrate to the first gas after stopping the generation of the plasma.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] SUMMARY Exemplary embodiments of the present disclosure relate to a substrate processing method and a substrate processing apparatus. [Background technology]

[0002] There are known techniques for modifying the surface of a substrate or forming a film on the substrate by irradiating it with electrons. For example, Non-Patent Document 1 below describes the formation of a ruthenium thin film on a substrate containing silicon or titanium at a temperature of 160°C or less by using electron-enhanced atomic vapor deposition (EE-ALD) by continuously irradiating the substrate with low-energy electrons. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] Michael A.Collings, Marcel Junige, Andrew S. Cavanagh, Victor Wang, Andrew C. Kummel, andSteven M. George, "Electron-enhanced atomic layer deposition of Ru thin films using Ru(DMBD)(CO)3 and effect of forming gas anneal", Journal of Vacuum Science & Technology A, vol.41, issue 6, 062408, 2023 Summary of the Invention [Problem to be solved by the invention]

[0004] Since electrons are lighter than ions, even if electrons are accelerated with high energy, their momentum is small, and they have the advantage of causing less physical damage to the substrate. Also, compared to using light, using electrons makes it easier to impart high energy to the substrate. On the other hand, the method described in Non-Patent Document 1 mentioned above uses 4cm2 In this method, electrons are irradiated onto a very small area, making it difficult to irradiate a large substrate with electrons uniformly. Furthermore, if electrons are continuously irradiated onto the substrate, the substrate may become negatively charged, reducing the efficiency of electron irradiation onto the substrate.

[0005] Therefore, there is a need to provide a substrate processing method and a substrate processing apparatus that can efficiently irradiate a substrate with electrons. [Means for solving the problem]

[0006] In one exemplary embodiment, a substrate processing method is provided for processing a substrate supported by a substrate support in a processing vessel defining an internal space including a first space and a second space, the substrate processing method including the steps of: generating plasma of a first gas in the first space; applying a potential lower than that of the substrate support to a mesh member disposed between the first space and the second space, the mesh member having a plurality of through-holes for selectively transmitting electrons in the plasma generated in the first space to the second space; and irradiating the substrate disposed in the second space with the electrons that have transmitted through the mesh member; and, after stopping the generation of the plasma, exposing the substrate to the first gas to remove negative charges that have been accumulated on the substrate by the electron irradiation. [Effects of the Invention]

[0007] According to one exemplary embodiment, the substrate can be efficiently irradiated with electrons. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram illustrating a substrate processing apparatus according to an exemplary embodiment; [Figure 2] FIG. 2 is a top view illustrating an exemplary first mesh member. [Figure 3] FIG. 10 is a top view illustrating an exemplary second mesh member. [Figure 4] 10A and 10B are diagrams illustrating an example of the movement of charged particles within the through-holes of the first mesh member. [Figure 5]1 is a diagram illustrating an example of the movement of charged particles in a plasma. [Figure 6] FIG. 4 is a diagram showing an example of a waveform of a pulse voltage. [Figure 7] 1 is a flowchart illustrating a substrate processing method according to an exemplary embodiment. [Figure 8] 1 is a timing chart illustrating a substrate processing method according to an exemplary embodiment. [Figure 9] 1(a), 1(b), and 1(c) are cross-sectional views showing a step of a substrate processing method. [Figure 10] 1(a), 1(b), and 1(c) are cross-sectional views showing a step of a substrate processing method. [Figure 11] FIG. 2 is a cross-sectional view showing a substrate on which a SiC film is formed. [Figure 12] FIG. 10 is a diagram illustrating a schematic view of a substrate processing apparatus according to another exemplary embodiment. [Figure 13] 10 is a timing chart illustrating a substrate processing method according to another exemplary embodiment. [Figure 14] FIG. 1 is a diagram showing a schematic diagram of the plasma ignition process together with the potential distribution. DETAILED DESCRIPTION OF THE INVENTION

[0009] Various exemplary embodiments are described below.

[0010] In one exemplary embodiment, a substrate processing method is provided for processing a substrate supported by a substrate support in a processing vessel defining an internal space including a first space and a second space, the substrate processing method including the steps of: generating plasma of a first gas in the first space; applying a potential lower than that of the substrate support to a mesh member disposed between the first space and the second space, the mesh member having a plurality of through-holes for selectively transmitting electrons in the plasma generated in the first space to the second space; and irradiating the substrate disposed in the second space with the electrons that have transmitted through the mesh member; and, after stopping the generation of the plasma, exposing the substrate to the first gas to remove negative charges that have been accumulated on the substrate by the electron irradiation.

[0011] In the substrate processing method according to the above embodiment, a potential lower than that of the substrate support is applied to the mesh member, and the potential difference between the mesh member and the substrate support is used to accelerate electrons toward the substrate, generating an electron beam, which then irradiates the substrate with electrons that have passed through the mesh member. This method allows large substrates to be irradiated with electrons with high uniformity. Furthermore, in this substrate processing method, negative charges on the substrate are removed by exposing the substrate to the first gas, thereby preventing a decrease in the potential difference between the mesh member and the substrate due to substrate charging. This allows electrons to be efficiently irradiated onto the substrate.

[0012] In one exemplary embodiment, the pressure in the second space during the step of removing negative charges may be higher than the pressure in the second space during the step of irradiating electrons. By making the pressure in the second space relatively higher during the step of removing negative charges, contact between the substrate and the first gas can be promoted. As a result, negative charges can be efficiently removed from the substrate.

[0013] In one exemplary embodiment, the method may further include a step of supplying a second gas into the second space after the step of removing the negative charges. By irradiating the substrate with electrons and removing the negative charges on the substrate, a highly reactive active layer is formed on the surface of the substrate. By supplying the second gas after the step of removing the negative charges, the second gas reacts with the active layer and a film derived from the second gas can be formed on the substrate.

[0014] In one exemplary embodiment, the first gas may include argon and the second gas may include vinylsilane, which may form a SiC film on the substrate.

[0015] In one exemplary embodiment, the method may further include the step of supplying a third gas into the second space before the step of removing the negative charge.

[0016] In one exemplary embodiment, the first gas may include argon, the second gas may include ozone, and the third gas may include disilane. 2 A film can be formed.

[0017] In one exemplary embodiment, during the electron irradiation step, a pulse voltage that periodically varies between a first voltage level and a second voltage level is applied to the mesh member. The first voltage level may be a voltage level for accelerating electrons so that their kinetic energy becomes lower than the ionization energy of the first gas, and the second voltage level may be a voltage level for accelerating electrons so that their kinetic energy becomes higher than the ionization energy of the first gas. In this periodic pulse voltage application, ions are generated from the first gas during the period when the voltage at the second voltage level is applied. If the voltage at the second voltage level continues to be applied, plasma will eventually be ignited. By returning the applied voltage to the first voltage level before plasma ignition, it is possible to irradiate the substrate with electrons only without igniting plasma. Furthermore, by periodically applying a voltage at the second voltage level, which is higher than the first voltage level, to the mesh member, the electric field strength between the mesh member and the substrate support is strengthened, which alleviates the space charge limiting effect and increases the current density (electron density and electron movement velocity) of the electron beam, thereby increasing the number of electrons irradiated to the substrate. Therefore, this substrate processing method can efficiently process the substrate while suppressing damage to the substrate.

[0018] In one exemplary embodiment, the first gas may include argon, the first voltage level may be a voltage level for accelerating electrons so that their kinetic energy becomes lower than 15.8 eV, and the second voltage level may be a voltage level for accelerating electrons so that their kinetic energy becomes higher than 15.8 eV. Since the ionization energy of argon gas is 15.8 eV, when electrons collide with the argon gas at the second voltage level, the argon gas is ionized, generating argon ions. The generated ions are accelerated toward the mesh member by the electric field. If the second voltage level is applied steadily, an electron avalanche occurs, igniting (generating) plasma. However, by applying the second voltage level in a pulsed manner with a pulse width shorter than the time it takes for plasma to ignite, the applied voltage returns to the first voltage level before plasma ignition. When the first voltage level is applied, the electron energy becomes lower than 15.8 eV. Therefore, no ions are generated from the argon gas during the application of the first voltage level. By setting the application time of the first voltage level to be longer than the time required for ions generated by the previous application of the second pulse to reach the mesh, the first and second voltage levels can be periodically varied without igniting plasma. Furthermore, since the second voltage level is relatively higher than the first voltage level, the space charge limitation is alleviated compared to when the first voltage level is applied, allowing for an increase in the current density between the mesh member and the substrate. Therefore, electrons can be efficiently irradiated onto the substrate while suppressing ion irradiation damage to the substrate.

[0019] In one exemplary embodiment, the first gas contains helium, the first voltage level is a voltage level for accelerating electrons so that their kinetic energy is lower than 24.6 eV, and the second voltage level is a voltage level for accelerating electrons so that their kinetic energy is higher than 24.6 eV. When electrons having an energy higher than 24.6 eV are irradiated onto the helium gas, the helium gas is ionized to generate helium ions. Therefore, by setting the first and second voltage levels as described above, it is possible to efficiently irradiate the substrate with electrons while suppressing plasma generation and ion irradiation damage to the substrate.

[0020] In one exemplary embodiment, the pulse voltage may have a pulse width and a duty ratio that prevent plasma of the first gas from being ignited in the second space. By preventing plasma of the first gas from being ignited, ion irradiation damage to the substrate can be more effectively suppressed.

[0021] a mesh member disposed between the first and second spaces and having a plurality of through holes for selectively transmitting electrons in the plasma generated in the first space to the second space; an energy supply unit configured to apply a voltage to the mesh member to supply energy to the electrons in the second space; and a control device. The control device is configured to control the first gas supply unit, the plasma generation unit, and the energy supply unit to perform the following steps: generating plasma of the first gas in the first space; applying a potential to the mesh member that is lower than the potential of the substrate support to irradiate a substrate disposed in the second space with electrons that have transmitted through the mesh member; and exposing the substrate to the first gas after stopping the plasma generation to remove negative charges that have been accumulated on the substrate by irradiating the substrate with electrons.

[0022] According to the substrate processing apparatus of the above embodiment, it is possible to efficiently irradiate electrons onto the substrate.

[0023] According to an exemplary embodiment, the substrate processing apparatus further includes an exhaust device configured to reduce the pressure in the internal space, and the control device may control the exhaust device so that the pressure in the second space during the step of removing negative charges is higher than the pressure in the second space during the step of irradiating with electrons. By relatively increasing the pressure in the second space during the step of removing negative charges, contact between the substrate and the first gas can be promoted, and as a result, negative charges can be efficiently removed from the substrate.

[0024] According to one exemplary embodiment, the substrate processing apparatus further includes a second gas supply unit configured to supply a second gas to the second space, and the control device may control the second gas supply unit to supply the second gas to the second space after negative charges on the substrate are removed. By irradiating the substrate with electrons and removing the negative charges on the substrate, a highly active layer is formed on the surface of the substrate. By supplying the second gas after the step of removing the negative charges, the second gas reacts with the active layer to form a film derived from the second gas on the substrate.

[0025] According to an exemplary embodiment, the substrate processing apparatus may further include an ion collector electrode disposed in the first space and configured to collect ions in the plasma. By collecting ions in the plasma with the ion collector electrode, non-ambipolar diffusion can be generated between the ion collector electrode and the mesh member, and electrons can be extracted from the mesh member to the second space more efficiently.

[0026] In one exemplary embodiment, the energy supplier may apply a potential to the ion collector electrode that is lower than the potential of the mesh member. By relatively increasing the potential of the mesh member, leakage of ions from the first space to the second space can be suppressed. Therefore, leakage of ions from the mesh member to the second space can be suppressed, and ion irradiation damage to the substrate can be suppressed.

[0027] In one exemplary embodiment, the energy supply unit applies a pulse voltage to the mesh member that periodically varies between a first voltage level and a second voltage level, the first voltage level being a voltage level for accelerating electrons so that their kinetic energy becomes lower than the ionization energy of the first gas, and the second voltage level being a voltage level for accelerating electrons so that their kinetic energy becomes higher than the ionization energy of the first gas. As described above, by applying a pulse voltage to the mesh member, it is possible to efficiently process substrates while suppressing damage to the substrates.

[0028] In one exemplary embodiment, the first gas includes argon, the first voltage level is a voltage level for accelerating electrons so that their kinetic energy becomes lower than 15.8 eV, and the second voltage level is a voltage level for accelerating electrons so that their kinetic energy becomes higher than 15.8 eV. In this case, the substrate can be efficiently irradiated with electrons while suppressing ion irradiation damage to the substrate.

[0029] In one exemplary embodiment, the first gas includes helium, the first voltage level is a voltage level for accelerating electrons so that their kinetic energy becomes lower than 24.6 eV, and the second voltage level is a voltage level for accelerating electrons so that their kinetic energy becomes higher than 24.6 eV. In this case, the substrate can be efficiently irradiated with electrons while suppressing ion irradiation damage to the substrate.

[0030] In one exemplary embodiment, the pulse voltage may have a pulse width and a duty ratio that prevent plasma of the first gas from being ignited in the second space. By preventing plasma of the first gas from being ignited, ion irradiation damage to the substrate can be more effectively suppressed.

[0031] According to one exemplary embodiment, the substrate processing apparatus further includes a second mesh member separate from the first mesh member, the second mesh member being disposed between the first mesh member and the substrate support, the energy supply unit including a first DC power supply that applies a voltage to the first mesh member such that the potential of the first mesh member is lower than the potential of the second mesh member, and a second DC power supply that applies a voltage to the second mesh member such that the potential of the second mesh member is lower than the potential of the substrate support, and at least one of the first DC power supply and the second DC power supply may be a variable DC power supply that generates a pulsed voltage. By providing the second mesh member between the first mesh member and the substrate support, it is possible to more effectively suppress ions in the plasma from irradiating the substrate.

[0032] Various exemplary embodiments will be described in detail below with reference to the drawings, in which the same or equivalent parts are designated by the same reference numerals.

[0033] Fig. 1 is a diagram schematically illustrating a substrate processing apparatus according to an exemplary embodiment. The substrate processing apparatus 1 illustrated in Fig. 1 is an inductively coupled substrate processing apparatus. The substrate processing apparatus 1 is an apparatus for processing a substrate by irradiating the substrate with an electron beam.

[0034] As shown in FIG. 1, the substrate processing apparatus 1 includes a processing vessel 10, a plasma generation unit 11, a substrate support 12, a first gas supply unit 13, a second gas supply unit 14, a first mesh member 15, a second mesh member 16, and an energy supply unit 17.

[0035] The processing vessel 10 has a substantially cylindrical shape and defines an internal space 10s therein. The processing vessel 10 includes a dielectric window 101 and a sidewall 102. The sidewall 102 is made of, for example, aluminum. A plasma-resistant and radical-resistant film is formed on the inner surface of the sidewall 102. This film may be a film formed by anodizing or a ceramic film such as a film formed from yttrium oxide.

[0036] The processing vessel 10 is electrically grounded. A passage 10p is formed in the lower part of a sidewall 102 of the processing vessel 10. The substrate W passes through the passage 10p when being transferred between the internal space 10s and the outside of the processing vessel 10. A gate valve 10g is provided along the sidewall of the vessel lower part 10B to open and close the passage 10p.

[0037] The plasma generation unit 11 includes an antenna 20. The antenna 20 is disposed on or above the processing vessel 10 (i.e., on or above the dielectric window 101). The antenna 20 includes one or more coils. In one embodiment, the antenna 20 may include an outer coil and an inner coil arranged coaxially. In this case, the high-frequency power supply 30, which will be described later, may be connected to both the outer coil and the inner coil, or to either the outer coil or the inner coil.

[0038] The substrate processing apparatus 1 includes a gas introduction unit configured to introduce a first gas G1 into the internal space 10s. In one embodiment, the gas introduction unit includes a center gas injector (CGI) 21. The center gas injector 21 is attached to a central opening formed in the dielectric window 101. The center gas injector 21 has a gas supply port 21a, a gas flow path 21b, and a gas inlet port 21c. Note that the gas introduction unit may include one or more side gas injectors (SGI) attached to one or more openings formed in the sidewall 102 in addition to or instead of the center gas injector 21. The first gas supply unit 13 is connected to the gas supply port 21a.

[0039] The first gas supply unit 13 includes a valve 25, a flow rate controller 26, and a gas source 27. The valve 25 switches between supplying and stopping the supply of the first gas G1 to the gas supply port 21a. The flow rate controller 26 is a mass flow controller or a pressure-controlled flow rate controller. The gas source 27 is connected to the gas supply port 21a via the valve 25 and the flow rate controller 26. The gas source 27 supplies the first gas G1 to the gas supply port 21a via the valve 25 and the flow rate controller 26.

[0040] The first gas G1 is a gas for generating plasma. For example, the first gas G1 is an inert gas such as helium gas (He), argon gas (Ar), krypton gas (Kr), or xenon gas (Xe). The first gas G1 may be hydrogen gas or a mixed gas containing an inert gas and hydrogen gas. The first gas G1 supplied from the first gas supply unit 13 is supplied to the plasma generation space S1 via the gas supply port 21a, the gas flow path 21b, and the gas inlet port 21c. As described above, the first gas supply unit 13 can supply the first gas G1 to the plasma generation space S1 at a regulated flow rate.

[0041] The plasma generation unit 11 further includes a high-frequency power supply 30. The high-frequency power supply 30 is connected to the antenna 20 via a matching box 31 and generates power for plasma generation. The high-frequency power supply 30 supplies high-frequency power having a frequency within a range of, for example, 400 kHz to 150 MHz to the antenna 20. In one embodiment, the high-frequency power supply 30 may be configured to generate a plurality of source RF signals having different frequencies. The matching box 31 has a matching circuit for matching the output impedance of the high-frequency power supply 30 with the impedance of the load side (antenna 20). The matching circuit of the matching box 31 may include a capacitor.

[0042] When power is supplied from the high-frequency power supply 30 to the antenna 20, the first gas G1 is excited in the plasma generation space S1, and plasma PL of the first gas G1 is generated. The plasma PL contains charged particles such as positive ions and electrons. For example, if the first gas G1 is argon gas, the plasma PL contains positive argon ions and negative electrons.

[0043] The substrate support 12 is provided at the bottom of the internal space 10s and is configured to support the substrate W placed thereon. The substrate W has, for example, a substantially disk shape. The substrate support 12 is electrically grounded.

[0044] In one embodiment, the substrate support 12 includes a lower electrode 41 and an electrostatic chuck 42. The lower electrode 41 is made of a conductive material such as aluminum and has a substantially disk shape. A flow path 41f may be formed within the lower electrode 41. The flow path 41f is a flow path for a heat exchange medium. As the heat exchange medium, a liquid refrigerant or a refrigerant (e.g., chlorofluorocarbon) that cools the lower electrode 41 by vaporizing is used. A heat exchange medium circulation device (e.g., a chiller unit) is connected to the flow path 41f. This circulation device is installed outside the processing chamber 10. The heat exchange medium is supplied to the flow path 41f from the circulation device via piping (not shown). The heat exchange medium supplied to the flow path 41f is returned to the circulation device via piping (not shown). In another embodiment, the substrate support 12 may include a lower electrode and a heater.

[0045] The electrostatic chuck 42 is provided on the lower electrode 41. When the substrate W is processed in the processing space S2, it is placed on the electrostatic chuck 42 and held by the electrostatic chuck 42. The electrostatic chuck 42 has a body and an electrode. The body of the electrostatic chuck 42 is formed from a dielectric material such as aluminum oxide or aluminum nitride. The body of the electrostatic chuck 42 has a substantially disk shape. The electrostatic chuck 42 includes a substrate mounting region and a focus ring mounting region. The substrate mounting region is a region having a substantially disk shape. The upper surface of the substrate mounting region extends along a horizontal plane. An axis AX that includes the center of the substrate mounting region and extends vertically substantially coincides with the central axis of the processing vessel 10. When the substrate W is processed in the processing vessel 10, it is placed on the upper surface of the substrate mounting region.

[0046] The focus ring mounting region extends in the circumferential direction to surround the substrate mounting region. A focus ring FR is mounted on the upper surface of the focus ring mounting region. The focus ring FR has an annular shape. The substrate W is disposed within the region surrounded by the focus ring FR. That is, the focus ring FR surrounds the edge of the substrate W mounted on the substrate mounting region of the electrostatic chuck 42. The focus ring FR is made of, for example, silicon or silicon carbide.

[0047] The electrodes of the electrostatic chuck 42 are provided within the body of the electrostatic chuck 42. The electrodes of the electrostatic chuck 42 are films formed from a conductor. A DC power supply is electrically connected to the electrodes of the electrostatic chuck 42. When a DC voltage is applied from the DC power supply to the electrodes of the electrostatic chuck 42, an electrostatic attractive force is generated between the electrostatic chuck 42 and the substrate W. The generated electrostatic attractive force attracts the substrate W to the electrostatic chuck 42 and the substrate W is held by the electrostatic chuck 42.

[0048] An exhaust pipe 43 is connected to the bottom of the processing vessel 10 at a position between the substrate support 12 and the sidewall 102 of the processing vessel 10. An exhaust device 44 is connected to the exhaust pipe 43. The exhaust device 44 has a pressure controller such as an automatic pressure control valve and a vacuum pump such as a turbomolecular pump, and can reduce the pressure in the internal space 10s.

[0049] The first mesh member 15 is provided in the processing vessel 10 and divides the internal space 10s into a plasma generation space S1 and a processing space S2. That is, the first mesh member 15 is disposed between the plasma generation space S1 and the processing space S2. The plasma generation space S1 is a space for generating plasma therein, and is formed between the first mesh member 15 and the dielectric window 101. The processing space S2 is a space for processing the substrate W, and is formed between the substrate support 12 and the first mesh member 15. That is, the substrate W is disposed in the processing space S2.

[0050] FIG. 2 is a top view schematically illustrating an exemplary first mesh member 15. As shown in FIG. 2, the first mesh member 15 includes an insulating plate 51 and multiple lattice portions 52. The insulating plate 51 is made of an insulator such as quartz and is formed in a substantially disk shape. The multiple lattice portions 52 are made of a conductive material and are arranged two-dimensionally within the insulating plate 51. Each of the multiple lattice portions 52 has multiple through-holes 15h that penetrate the first mesh member 15 in the thickness direction. The multiple through-holes 15h communicate between the plasma generation space S1 and the processing space S2. The multiple through-holes 15h have an opening width that blocks ions in the plasma PL generated in the plasma generation space S1 and allows electrons in the plasma PL to pass from the plasma generation space S1 to the processing space S2.

[0051] The opening width of the plurality of through holes 15h refers to the width of the opening formed in the first mesh member 15 by each of the through holes 15h. For example, if the planar shape of the through holes 15h is circular, the diameter of the through holes 15h is defined as the opening width of each of the through holes 15h. If the planar shape of the opening is a regular polygon, the diameter of a circle inscribed in the regular polygonal opening is defined as the opening width of each of the through holes 15h. The first mesh member 15 shown in Fig. 2 has a plurality of through holes 15h, each of which has a substantially square planar shape.

[0052] The lattice portion 52 of the first mesh member 15 is connected to the negative electrode of a DC power supply 54 (described later) via a wire WR2. The wire WR2 may be covered with an insulator such as quartz. The plurality of through holes 15h may be formed over substantially the entire surface of the first mesh member 15.

[0053] The second mesh member 16 is disposed between the substrate support 12 and the first mesh member 15 in the processing space S2. In one embodiment, the second mesh member 16 is formed in a disk shape and is made of a metal such as stainless steel or aluminum. The surface of the second mesh member 16 may be coated with a radical-resistant film or may be conductive. The second mesh member 16 is supported on the sidewall 102 of the processing vessel 10 via an insulating member 18. The insulating member 18 is made of ceramic such as quartz. That is, the second mesh member 16 is electrically insulated from the processing vessel 10.

[0054] FIG. 3 is a top view schematically illustrating an exemplary second mesh member 16. As shown in FIG. 3, the second mesh member 16 has an outer peripheral portion 61 and a lattice portion 62. The outer peripheral portion 61 is formed in an annular shape. The lattice portion 62 has a mesh structure, a honeycomb structure, or a multi-hole structure, and is connected to the inner peripheral edge of the outer peripheral portion 61. The lattice portion 62 of the second mesh member 16 has a plurality of through holes 16h formed therein that penetrate the second mesh member 16 in the thickness direction. In one embodiment, the opening width of the plurality of through holes 15h of the first mesh member 15 may be smaller than the opening width of the plurality of through holes 16h of the second mesh member 16.

[0055] The opening width of the plurality of through holes 16h refers to the width of the opening formed by each through hole 16h in the second mesh member 16. For example, if the planar shape of the through hole 16h is circular, the diameter of the circular opening is defined as the opening width of each through hole 16h, and if the planar shape of the opening is a regular polygon, the diameter of a circle inscribed in the regular polygonal opening is defined as the opening width of each through hole 16h.

[0056] In one embodiment, as shown in FIG. 3, a gas diffusion chamber 16a is formed inside the second mesh member 16. The gas diffusion chamber 16a extends in an annular shape along the outer circumferential portion 61 of the second mesh member 16. A lattice-shaped gas passage 16b is connected to the gas diffusion chamber 16a. The lattice-shaped gas passage 16b is formed inside a lattice portion 62. The gas passage 16b may be formed throughout the entire lattice portion 62, or may be formed only in a portion of the lattice portion 62. A plurality of gas discharge holes 16c are formed in the lattice portion 62, communicating with the gas passage 16b and opening toward the processing space S2 (see FIG. 1). The plurality of gas discharge holes 16c are formed so as to face the substrate W placed on the substrate support 12. The plurality of gas discharge holes 16c are connected to the gas diffusion chamber 16a via the gas passage 16b.

[0057] A gas introduction port 63 is connected to the gas diffusion chamber 16a. A gas supply pipe 64 is connected to the gas introduction port 63. A second gas supply unit 14 is connected to the gas supply pipe 64. The second gas supply unit 14 includes a valve 65, a flow rate controller 66, and a gas source 67. The valve 65 has a function of switching between supplying and stopping gas to the gas supply pipe 64. The flow rate controller 66 is a mass flow controller or a pressure-controlled flow rate controller. The gas source 67 is connected to the gas supply pipe 64 via the valve 65 and the flow rate controller 66. The gas source 67 supplies the second gas G2 to the gas supply pipe 64 via the valve 65 and the flow rate controller 66.

[0058] The second gas G2 is, for example, a raw material gas (precursor) for forming a film on the substrate W, and is selected depending on the type of film to be formed on the substrate W. For example, when forming a SiC film on a SiO2 substrate W, the second gas G2 contains vinylsilane (CH2=CH-SiH3). The second gas G2 supplied from the second gas supply unit 14 is supplied to the processing space S2 via the gas supply pipe 64, the gas diffusion chamber 16a, the gas passage 16b, and the plurality of gas outlet holes 16c. As described above, the second gas supply unit 14 can supply the second gas G2 to the processing space S2 at an adjusted flow rate.

[0059] In one embodiment, the substrate processing apparatus 1 may further include an ion collector electrode 80. The ion collector electrode 80 is provided in the plasma generation space S1. The ion collector electrode 80 has a substantially disk shape and is made of a metal such as stainless steel or aluminum. The ion collector electrode 80 has a honeycomb structure or a mesh structure and has a plurality of through-holes 80p penetrating in the thickness direction.

[0060] The ion collector electrode 80 is configured to collect ions in the plasma PL by applying a voltage thereto. Therefore, as described below, a negative voltage lower than the potential of the first mesh member 15 is applied to the ion collector electrode 80. The surface area of ​​the ion collector electrode 80 may be larger than the surface area of ​​the first mesh member 15. For example, the surface area of ​​the ion collector electrode 80 may be 17 times or more, 33 times or more, or 105 times or more the surface area of ​​the first mesh member 15. By making the surface area of ​​the ion collector electrode 80 larger than the surface area of ​​the first mesh member 15, ions flow into the ion collector electrode 80, while electrons are attracted to the first mesh member 15. In other words, a non-ambipolar diffusion flow is formed, and electrons in the plasma PL can be efficiently transported to the first mesh member 15.

[0061] In one embodiment, the energy supply unit 17 includes a variable DC power supply 50, a DC power supply 54, and a DC power supply 55. The variable DC power supply 50 generates a voltage for accelerating electrons that have passed through the plurality of through-holes 15h of the first mesh member 15. The anode of the variable DC power supply 50 is electrically grounded. The negative electrode of the variable DC power supply 50 is electrically coupled to the second mesh member 16 via a wiring WR1. The variable DC power supply 50 applies a negative pulse voltage Vp to the second mesh member 16 so that the potential of the second mesh member is lower than the potential of the substrate support 12.

[0062] The positive electrode of the DC power supply 54 is electrically connected to the second mesh member 16 and the negative electrode of the variable DC power supply 50. The negative electrode of the DC power supply 54 is electrically connected to the first mesh member 15 via a wiring WR2. The DC power supply 54 applies a DC voltage Vc1 between the first mesh member 15 and the second mesh member 16 so that the potential of the first mesh member 15 is lower than the potential of the second mesh member 16.

[0063] The positive electrode of the DC power supply 55 is electrically connected to the first mesh member 15 and the negative electrode of the DC power supply 54. The negative electrode of the DC power supply 55 is electrically connected to the ion collector electrode 80 via a wire WR3. The DC power supply 55 applies a DC voltage Vc2 between the first mesh member 15 and the ion collector electrode 80 so that the potential of the ion collector electrode 80 is lower than the potential of the first mesh member 15. Therefore, the potentials of the ion collector electrode 80, first mesh member 15, second mesh member 16, and substrate support 12 increase in this order.

[0064] As described above, a potential difference occurs between the first mesh member 15 and the substrate support 12, and an electric field E is formed between the first mesh member 15 and the substrate support 12, i.e., in the processing space S2, from the substrate support 12 to the first mesh member 15 (see Figure 4).

[0065] The movement of charged particles in the plasma PL will be described with reference to Figures 4 and 5. In Figures 4 and 5, circles surrounding "+" and circles surrounding "-" represent positive ions and electrons, respectively.

[0066] As shown in FIG. 4, the plasma PL of the first gas G1 generated in the plasma generation space S1 contains positive ions and electrons. Because electrons have a lighter mass and higher mobility than positive ions, a sheath 70 is formed between the first mesh member 15 and the plasma PL, and the first mesh member 15 has a negative potential relative to the potential of the plasma PL. Therefore, when positively charged positive ions in the plasma PL reach the end of the sheath 70, an attractive force acts toward the first mesh member 15 due to the electric field formed within the sheath 70. This attractive force causes the positive ions to be attracted to the first mesh member 15 and collide with it, as shown in FIG. 4. The positive ions that collide with the first mesh member 15 lose their charge and return to an electrically neutral gas. Therefore, the first mesh member 15 functions to block the movement of positive ions in the plasma PL from the plasma generation space S1 to the processing space S2.

[0067] On the other hand, a repulsive force acts between negatively charged electrons and the first mesh member 15. Therefore, as shown in Fig. 4, electrons in the plasma PL move from the plasma generation space S1 to the processing space S2 through the multiple through-holes 15h without colliding with the first mesh member 15. That is, the first mesh member 15 has the function of selectively transmitting electrons out of the positive ions and electrons in the plasma PL. In particular, by making the opening width of the through-holes 15h smaller than twice the sheath width, it becomes possible to selectively move only electrons to the processing space S2.

[0068] 5, electrons that pass through the multiple through-holes 15h of the first mesh member 15 receive energy from the electric field E formed in the processing space S2 and are accelerated. As a result, an electron beam 60 is formed in the processing space S2. At this time, the traveling direction of the electron beam 60 is aligned parallel to the axis AX by the voltage applied to the second mesh member 16. The electron beam 60 is attracted to the substrate support 12, which has a relatively positive potential, and collides with the substrate W supported on the substrate support 12. As a result, the energy of the electrons is supplied to the substrate W, and the surface of the substrate W is processed.

[0069] If electrons are continuously extracted from the plasma PL into the processing space S2 to generate the electron beam 60, the potential of the plasma PL may become positive, which may reduce the electron extraction efficiency. In contrast, in the substrate processing apparatus 1, an ion collector electrode 80 to which a negative voltage is applied is disposed in the plasma generation space S1, so that positively charged ions are drawn into the ion collector electrode 80 as they pass through the multiple through-holes 80p. The ions drawn into the ion collector electrode 80 are captured by the ion collector electrode 80, receive electrons from the ion collector electrode 80, lose their charge, and return to neutral gas. As a result, the potential of the plasma PL is prevented from rising positively, thereby improving the electron extraction efficiency.

[0070] Here, a portion of the first gas G1 may leak from the plasma generation space S1 into the processing space S2. For example, this may occur when the opening width of the through-holes 15h is sufficiently larger than twice the width of the sheath formed on the surface of the first mesh member. Furthermore, if excessive energy is supplied to the first gas G1 leaking into the processing space S2 by irradiation with the electron beam 60, plasma of the first gas G1 may be generated in the processing space S2. Ions in this plasma are accelerated by the potential difference between the ions and the substrate W and collide with the substrate W. The ion collisions cause physical damage (ion irradiation damage) to the surface of the substrate W.

[0071] For example, the ionization energy of argon is 15.8 eV. Therefore, when the first gas G1 is argon gas, argon ions are generated from the argon gas when electrons having an energy of 15.8 eV or more are irradiated onto the argon gas. Furthermore, the ionization energy of helium is 24.6 eV. Therefore, when the first gas G1 is helium gas, helium ions are generated from the helium gas when electrons having an energy of 24.6 eV or more are irradiated onto the helium gas leaked into the processing space S2. These ions are accelerated by the potential difference between the plasma generated in the processing space S2 and the substrate W, and may collide with the substrate W and cause physical damage to the substrate W. To prevent such damage, the energy supply unit 17 supplies a pulsed voltage to the first mesh member 15 to prevent the plasma of the first gas G1 from igniting in the processing space S2.

[0072] FIG. 6 shows an example of the waveform of the pulse voltage Vt applied between the first mesh member 15 and the substrate support 12. This pulse voltage Vt is a composite voltage of the DC voltage Vc1 applied to the first mesh member 15 from the DC power supply 54 and the pulse voltage Vp applied to the second mesh member 16 from the variable DC power supply 50. The waveform shown in FIG. 6 shows the change in the absolute value of the pulse voltage Vt applied to the first mesh member 15. As shown in FIG. 6, the voltage level (potential) of the pulse voltage Vt periodically changes between a first voltage level V1 and a second voltage level V2. Here, the ionization voltage Vion is defined as the voltage level for accelerating electrons so that their kinetic energy reaches an energy threshold (ionization energy) that ionizes the first gas G1. The absolute value of the first voltage level V1 is lower than the ionization voltage Vion. The absolute value of the second voltage level V2 is higher than the ionization voltage Vion.

[0073] As described above, the ionization energy of argon gas is 15.8 eV. Therefore, if the first gas G1 is argon gas and the energy (initial energy) of electrons immediately after moving to the processing space S2 is assumed to be approximately zero, the ionization voltage Vion is 15.8 V. Therefore, when the first gas G1 is argon gas, the first voltage level V1 can be lower than 15.8 V, and the second voltage level V2 can be higher than 15.8 V.

[0074] Moreover, the ionization energy of helium gas is 24.6 eV. That is, if the first gas G1 is helium gas and the energy (initial energy) of electrons immediately after moving to the processing space S2 is assumed to be approximately zero, the ionization voltage Vion is 24.6 V. Therefore, when the first gas G1 is helium gas, the first voltage level V1 can be lower than 24.6 V, and the second voltage level V2 can be higher than 24.6 V.

[0075] During the period τ1 during which the first voltage level V1 is applied, energy is supplied to electrons so that their energy is lower than the ionization energy of the first gas G1, thereby suppressing the generation of ions in the processing space S2. On the other hand, during the period τ2 during which the second voltage level V2 is applied, collisions between the electrons and the first gas G1 generate ions of the first gas G1 in the processing space S2. When the second voltage level V2 is continuously applied, plasma is ignited (generated) in the processing space S2. Here, with reference to FIG. 14, how plasma is generated when a voltage of the second voltage level V2 is steadily applied will be described. FIG. 14 shows the distribution of potential (voltage) relative to the position from the first mesh member 15 to the substrate W. Note that, if a second mesh member 16 is present, it is located between the first and second mesh members. State A1 in FIG. 14 is a state during which a voltage of the first voltage level V1 is steadily applied. The first voltage level V1 is a voltage level that accelerates electrons only to an energy level that does not exceed the ionization energy threshold of the gas, and is therefore in the range of 10 to 30 V, which is a very low level for a typical electron beam acceleration voltage. Unlike plasma, electron beams have only a single charge in the gas phase. Therefore, if the acceleration voltage is low or the number of supplied electrons is excessive, the space charge limiting effect becomes significant, limiting the amount of electron beam that can be extracted. According to the Child-Langmuir law, when space charge limiting occurs, the current density J flowing between the cathode and anode when a voltage is applied between them to generate an electron beam is expressed by the following equation (1). The voltage distribution between the cathode and anode at this time is expressed by the following equation (2).

[0076]

number

[0077]

number

[0078] In equation (1), ε0 represents the dielectric constant of a vacuum, m represents the electron mass, V0 represents the voltage between the cathode and anode, d represents the distance between the cathode and anode, and e represents the elementary charge. In equation (2), z represents the distance from the cathode. As shown in equation (1), the current density J between the cathode and anode is proportional to the 3 / 2 power of the voltage V0 applied between the cathode and anode. Therefore, reducing the voltage level also reduces the amount of electron beam that can be extracted. On the other hand, if excess electrons are supplied from the cathode in this state, a potential valley is formed near the cathode (corresponding to the first mesh member 15 in Figure 14), where electrons accumulate. This region where electrons accumulate is called a virtual cathode. In state A1 in Figure 14, the potential valley near the first mesh member 15 corresponds to the virtual cathode. When the applied voltage is increased stepwise to the second voltage level, the electric field becomes stronger. The electrons accumulated in the virtual cathode are accelerated toward the substrate W, and the potential valley begins to shallow (state A2). Some of the electrons ionize the second gas G2, but the electron supply from the first mesh member 15 is blocked by the (still remaining) potential valley, preventing efficient supply. This prevents plasma ignition (generation). As time passes, almost all of the electrons accumulated in the virtual cathode reach the substrate W, and the potential valley disappears (state A3). Then, electron emission from the cathode (first mesh member 15) becomes active. Since ionization has already begun, the space approaches electrical neutrality, eliminating the space charge limitation. This causes an electron avalanche, resulting in plasma ignition (state A4). Once plasma ignition is complete, the gas becomes more conductive, the potential in the plasma region becomes flat, and a sheath is formed primarily on the first mesh member 15 side (cathode side). It can be defined that plasma ignition occurs when a flat area is formed in the potential distribution and a sheath is formed. When the space is filled with electrons only and space charge is limited, the electron density is approximately 10 8 cm -3 The ion density is approximately 10 6 cm -3 When the plasma is ignited, the electron density and ion density both reach approximately 10 8 cm -3 That's all.

[0079] Next, the effect of applying a pulse voltage Vt that periodically varies between a first voltage level V1 and a second voltage level V2 to the first mesh member 15 will be described. When applying a periodic pulse, the application time τ2 of the pulse voltage at the second voltage level is set shorter than the time required for plasma to ignite, and the period τ1, which is the application time of the pulse voltage at the first voltage level V1, is set longer than the time required for ions generated during application of the second voltage level V2 to reach the first mesh member 15 and disappear. This allows the substrate W to be irradiated with an electron beam by repeatedly applying a pulse voltage without igniting plasma. That is, by appropriately setting the periods τ2 and τ1 (in other words, appropriately setting τ2 and the duty ratio), the substrate W can be processed without igniting plasma. Even if the period τ2 is a time width that prevents plasma ignition, if the ions are not reliably disappeared during the period τ1, the number of ions will cumulatively increase during the repeated application of pulses, leading to plasma ignition.

[0080] Applying a pulse voltage of the second voltage level V2 relaxes the space charge limitation and increases the electron beam current, and the electrons that had accumulated in the virtual cathode when the voltage of the first voltage level was applied are also efficiently irradiated onto the substrate W for processing.

[0081] As described above, in the period τ2, the electron energy becomes higher than the ionization energy, and therefore, if the duty ratio (=τ2 / (τ1+τ2)×100[%]), which is the ratio of the time length of the second voltage level V2 to the cycle of the pulse voltage Vp, becomes high, plasma is generated in the processing space S2. In this case, there is a risk of significant damage to the substrate W. Therefore, the pulse voltage Vt is set to a pulse width and duty ratio of the second voltage level V2 that will not ignite the plasma of the first gas G1.

[0082] The pulse width and duty ratio of the pulse voltage Vt that prevent plasma of the second gas G2 from igniting will be described below. As described above, when a voltage of the second voltage level V2 is applied to the first mesh member 15, ions of the first gas G1 are generated in the processing space S2. However, there is a time lag between the application of the voltage of the second voltage level V2 and the ignition of plasma of the first gas G1. It can be said that plasma ignites when a large amount of electrons are supplied from the first mesh member 15 immediately after the electrons constituting the virtual cathode reach the substrate W and the potential valley disappears (state A3 in FIG. 14). In other words, the time at which plasma ignites can be considered to be the time at which electrons from the virtual cathode reach the substrate W. Hereinafter, this time will be referred to as τp0. Because only a small amount of ionization occurs during the period τ2, the Child-Langmuir law described above applies. That is, the electrons reach the second mesh member 16 while being rate-limited by the space charge limited current Jp (Equation (3) below) determined by the second voltage level V2, and therefore the time τp0 until plasma ignition is expressed by Equation (4) below.

[0083]

number

[0084]

number

[0085] In equation (4), N is the surface density of electrons accumulated in the virtual cathode (virtual cathode width × electron density [m -2 The virtual cathode width is the thickness of the virtual cathode in the direction of electron beam travel.

[0086] On the other hand, while the first voltage level V1 is being applied, ions that were generated during the immediately preceding application of the second voltage level V2 and are present in the processing space S2 are accelerated by the electric field and reach the first mesh. The time τe0 for ions located at the farthest position from the first mesh, i.e., near the substrate W, to reach the first mesh is expressed by the following equation (5):

[0087]

number

[0088] In equation (5), M is the mass of the ion, and the electric field is derived by approximating it as constant at V1 / d regardless of location. In other words, to prevent plasma ignition, it is required that the period τ2 during which the voltage of the second voltage level V2 is applied is equal to or shorter than τp0, and that the period τ1 during which the voltage of the first voltage level V1 is applied is equal to or longer than τe0. The duty ratio in this case is expressed by equation (6) below. Plasma ignition can be avoided by setting the period τ2 to equal to or shorter than τe0, and setting the duty ratio of the pulse voltage Vp to equal to or shorter than the duty ratio D [%] shown in equation (6). This condition is equivalent to setting the period τ1 to equal to or longer than τe0, and setting the duty ratio to equal to or shorter than D.

[0089]

number

[0090] The substrate processing apparatus 1 further includes a control device MC. The control device MC is a computer including a processor, a storage device, an input device, a display device, etc., and controls each part of the substrate processing apparatus 1. Specifically, the control device MC executes a control program stored in the storage device and controls each part of the substrate processing apparatus 1 based on recipe data stored in the storage device. Under the control of the control device MC, a process specified by the recipe data is executed in the substrate processing apparatus 1. Substrate processing methods according to various embodiments are executed by the control of each part of the substrate processing apparatus 1 by the control device MC.

[0091] For example, the control device MC is communicatively connected to the plasma generation unit 11, the first gas supply unit 13, the second gas supply unit 14, the energy supply unit 17, and the exhaust device 44, and controls the operations of the plasma generation unit 11, the first gas supply unit 13, the second gas supply unit 14, the energy supply unit 17, and the exhaust device 44. For example, the control device MC sends a control signal to the high-frequency power supply 30 of the plasma generation unit 11 to control the generation of plasma PL in the plasma generation space S1 and the stop of the generation of plasma PL. The control device MC also sends a control signal to the valve 25 and the flow rate controller 26 of the first gas supply unit 13 to control the supply or stop of the supply of the first gas G1 to the plasma generation space S1. The control device MC also sends a control signal to the valve 65 and the flow rate controller 66 of the second gas supply unit 14 to control the supply or stop of the supply of the first gas G1 to the processing space S2.

[0092] Furthermore, the control device MC sends control signals to the variable DC power supply 50, the DC power supply 54, and the DC power supply 55 to control the supply or stop of voltage to the second mesh member 16, the first mesh member 15, and the ion collector electrode 80. The control device MC also sends a control signal to the exhaust device 44 to control the pressure in the internal space 10s (processing space S2).

[0093] Hereinafter, details of the control of the control device MC will be described with reference to Figures 7 and 8, and a substrate processing method according to one exemplary embodiment will be described. Figure 7 is a flowchart showing a substrate processing method according to one exemplary embodiment. Figure 8 is a timing chart showing the substrate processing method shown in Figure 7 (hereinafter referred to as "method MT"). The method MT is performed using the substrate processing apparatus 1 described above. Below, an example will be described in which a silicon carbide (SiC) film is formed on a substrate W made of SiO2 using atomic layer deposition (ALD).

[0094] As shown in FIG. 7, in the method MT, first, a substrate W is placed on a substrate support 12 (step ST1). The substrate W is, for example, a SiO substrate. The temperature of the substrate W is adjusted to, for example, 35° C. by a heater provided inside the substrate support 12. The substrate W may be washed with a cleaning liquid before being placed on the substrate support 12. When the substrate W is washed with a cleaning liquid, the surface of the substrate W is terminated with OH groups, as shown in FIG. 9(a). The surface of the substrate W may be terminated with OH groups by surface treatment such as plasma treatment.

[0095] Next, the control device MC controls the first gas supply unit 13 to supply the first gas G1 to the plasma generation space S1 (step ST2). The first gas G1 is, for example, an inert gas such as helium gas (He) or argon gas (Ar). As shown in FIG. 8, the first gas G1 is continuously supplied to the plasma generation space S1 during the execution of the method MT.

[0096] Next, the control device MC controls the high frequency power supply 30 of the plasma generating unit 11 to supply power to the antenna 20, thereby generating plasma PL of the first gas G1 in the plasma generating space S1 (step ST3).

[0097] Next, electrons in the plasma PL are drawn from the plasma generation space S1 to the processing space S2, and the electrons are irradiated onto the substrate W (step ST4). In order to draw the electrons in the plasma PL from the plasma generation space S1 to the processing space S2, the control device MC controls the energy supply unit 17 to apply a pulse voltage Vt to the first mesh member 15 so that the potential of the first mesh member 15 is lower than the potential of the substrate support 12. For example, the variable DC power supply 50 applies a negative pulse voltage Vp to the second mesh member 16 with respect to the potential of the substrate support 12, and the DC power supply 54 applies a negative DC voltage Vc1 to the first mesh member 15 with respect to the potential of the second mesh member 16. As a result, the potentials of the first mesh member 15, the second mesh member 16, and the substrate support 12 increase in this order.

[0098] A potential difference is generated between the first mesh member 15 and the substrate support 12, and an electric field E is formed in the processing space S2, directed from the substrate support 12 to the first mesh member 15. Electrons in the plasma PL receive energy from the electric field E and are accelerated to become an electron beam 60, which is then irradiated onto the substrate W. The surface of the substrate W is processed by irradiating the substrate W with the electron beam 60. For example, as shown in FIG. 9(b), the electron beam 60 collides with the surface of the substrate W and ejects terminating elements (e.g., hydrogen atoms) of the substrate W, thereby forming an active layer 91 having high activity, such as dangling bonds, on the surface of the substrate W.

[0099] 8, the irradiation of the substrate W with electrons continues for a time period t1. After the time period t1 has elapsed, the generation of the plasma PL is stopped, and the irradiation of the substrate W with the electron beam 60 is stopped. The time period t1 is, for example, 3 seconds. During the irradiation of the substrate W with electrons, the pressure in the processing space S2 is set to a pressure Pr0.

[0100] In one embodiment, the energy supplier 17 may apply a negative DC voltage Vc2 to the ion collector electrode 80 with respect to the potential of the first mesh member 15 during the generation of the plasma PL. By applying a negative voltage to the ion collector electrode 80, ions in the plasma PL are collected by the ion collector electrode 80. As a result, the potential of the plasma PL is prevented from becoming excessively positive.

[0101] When the substrate W is continuously irradiated with the electron beam 60, negative charges may accumulate on the substrate W, causing the substrate W to become negatively charged, as shown in FIG. 9B. Therefore, in the method MT, after stopping the plasma generation, the negative charges on the substrate W are removed (step ST5). Specifically, the control device MC controls the exhaust device 44 to change the pressure in the processing space S2 to a pressure Pr2 higher than the pressure Pr0. In step ST5, since the plasma generation is stopped, the first gas G1 moves from the plasma generation space S1 to the processing space S2 in an unionized state, and the substrate W is exposed to the first gas G1. When the substrate W is exposed to the first gas G1, which is an inert gas, the negative charges accumulated on the substrate W are removed, and the surface of the active layer 91 becomes closer to electrical neutrality, as shown in FIG. 9C. As shown in FIG. 8, the removal of the negative charges on the substrate W continues for a time period t2. The time period t2 is, for example, 3 seconds.

[0102] Next, the control device MC controls the second gas supply unit 14 to supply the second gas G2 to the processing space S2 (step ST6). The second gas G2 is, for example, vinylsilane (CH2=CH-SiH3). As shown in FIG. 8, in step ST6, the pressure in the processing space S2 may be maintained at pressure Pr2. The supply of the second gas G2 continues for a time period t3. The time period t3 is, for example, one second. After the time period t3 has elapsed, the supply of the second gas G2 is stopped.

[0103] 10(a), when vinylsilane is supplied to the processing space S2, the vinylsilane is adsorbed to the highly active active layer 91. As a result, a monolayer SiC layer 92 is formed on the surface of the substrate W.

[0104] After the supply of the second gas G2 is stopped, the processing space S2 is purged (step ST7). In one embodiment, the control device MC may control the exhaust device 44 to change the pressure of the processing space S2 to a pressure P1 higher than the pressure Pr0 and lower than the pressure Pr2. As a result, the processing space S2 is purged with the first gas G1, and the second gas G2 is removed from the processing space S2. As shown in FIG. 8, the purging of the processing space S2 continues for a time period t4. The time period t4 is, for example, 5 seconds. Note that, in one embodiment, after the supply of the first gas G1 is stopped to reduce the pressure in the processing space S2, the supply of the first gas G1 may be resumed to purge the processing space S2.

[0105] Next, the control device MC determines whether the sequence including steps ST4 to ST7 has been executed a predetermined number of times (step ST8). If it is determined that the sequence has not been executed a predetermined number of times, steps ST4 to ST7 are repeated until the sequence has been executed a predetermined number of times.

[0106] For example, if it is determined that the sequence has not been executed a predetermined number of cycles, the control device MC again generates plasma PL in the plasma generation space S1 and irradiates the substrate W with the electron beam 60 after the formation of the SiC layer 92 (step ST4). As a result, as shown in (b) of Fig. 10, the electron beam 60 collides with the surface of the substrate W and ejects terminating elements (e.g., hydrogen atoms) of the SiC layer 92, thereby forming an active layer 93 having high activity such as dangling bonds on the surface of the SiC layer 92.

[0107] Thereafter, the substrate W is exposed to a first gas G1, which is an inert gas, to remove negative charges on the substrate W (active layer 93) (step ST5). As a result, the surface of the active layer 93 is made closer to electrically neutral, as shown in FIG. 10(c). Next, a second gas G2 is supplied to the processing space S2 (step ST6). As a result, vinylsilane contained in the second gas G2 is adsorbed onto the surface of the active layer 93, and a monolayer SiC layer 92 is further formed on the active layer 93. Thereafter, the processing space S2 is purged (step ST7). As described above, by repeating the sequence including steps ST4 to ST7, a SiC film 95 is formed on the substrate W, as shown in FIG. 11.

[0108] As described above, in method MT, a potential lower than the potential of the substrate support 12 is applied to the first mesh member 15, and electrons that have passed through the first mesh member 15 are irradiated onto the substrate W due to the potential difference between the first mesh member 15 and the substrate support 12. With this configuration, it is possible to irradiate a large substrate W with electrons with high uniformity. Furthermore, in method MT, the negative charge on the substrate W is removed by exposing the substrate W to the first gas G1, so that a decrease in the potential difference between the first mesh member 15 and the substrate W due to charging of the substrate W is suppressed. Therefore, it is possible to continue to irradiate the substrate with electrons efficiently.

[0109] Furthermore, in the method MT, the pulse voltage Vt that periodically changes between the first voltage level V1 and the second voltage level V2 is applied to the first mesh member 15, so that the substrate W can be irradiated with high-energy electrons while suppressing ion irradiation damage to the substrate W. Therefore, the substrate W can be processed efficiently.

[0110] Next, a substrate processing apparatus according to another embodiment will be described with reference to Fig. 12. Fig. 12 is a cross-sectional view schematically showing a substrate processing apparatus 1A according to another embodiment. In the following description, differences from the substrate processing apparatus 1 shown in Fig. 1 will be mainly described, and overlapping descriptions will be omitted.

[0111] As shown in FIG. 12, the substrate processing apparatus 1A further includes a third gas supply unit 82. The third gas supply unit 82 is connected to the gas diffusion chamber 16a of the second mesh member 16. The third gas supply unit 82 includes a valve 83, a flow rate controller 84, and a gas source 85. The valve 83 has a function of switching between supplying and stopping the gas supply. The flow rate controller 84 is a mass flow controller or a pressure-controlled flow rate controller. The gas source 85 is connected to the gas diffusion chamber 16a via a valve 85 and a flow rate controller 66. The gas source 85 supplies a third gas G3 to the gas diffusion chamber 16a via the valve 83 and the flow rate controller 84.

[0112] That is, the substrate processing apparatus 1A is configured to selectively supply the second gas G2 and the third gas G3 to the processing space S2. The second gas G2 is, for example, a reactive gas (reactant), and the third gas G3 is, for example, a precursor gas. The second gas G2 and the third gas G3 are selected depending on the type of film to be formed on the substrate W. For example, when forming a SiO2 film on a silicon (Si) substrate W, the second gas G2 contains ozone (O3), and the third gas G3 contains disilane (Si2H6). The second gas G2 supplied from the second gas supply unit 14 and the third gas G3 supplied from the third gas supply unit 82 are supplied to the processing space S2 via the gas diffusion chamber 16a, the gas passage 16b, and the multiple gas outlet holes 16c. As described above, the substrate processing apparatus 1A can selectively supply the second gas G2 and the third gas G3 to the processing space S2 at adjusted flow rates.

[0113] A substrate processing method according to another embodiment will be described below with reference to Fig. 13. Fig. 13 is a timing chart showing a substrate processing method according to another embodiment. In the following, an example will be described in which an SiO2 film is formed on a silicon (Si) substrate W by atomic layer deposition.

[0114] In the substrate processing method shown in FIG. 13, first, a substrate W is placed on a substrate support 12. The substrate W is, for example, a Si substrate. The temperature of the substrate W is adjusted to, for example, 290°C by a heater provided inside the substrate support 12. Next, the control device MC controls the first gas supply unit 13 to supply a first gas G1 to the plasma generation space S1. The first gas G1 is, for example, an inert gas such as helium gas (He) or argon gas (Ar). The first gas G1 is continuously supplied to the plasma generation space S1 during execution of the substrate processing method shown in FIG. 13.

[0115] Next, the control device MC controls the third gas supply unit 82 to supply a third gas G3 to the processing space S2. The third gas G3 contains disilane (Si2H6) as a precursor. The disilane supplied to the processing space S2 is adsorbed onto the surface of the silicon substrate W. As shown in FIG. 13, the supply of the third gas G3 continues for a time period t11. After the time period t11 has elapsed, the supply of the third gas G3 is stopped. The time period t11 is, for example, one second. The pressure in the processing space S2 during the supply of the third gas G3 is set to, for example, a pressure Pr2.

[0116] After the supply of the third gas G3 is stopped, the control device MC controls the exhaust device 44 to change the pressure in the processing space S2 to pressure Pr1, which is lower than pressure Pr2. As a result, the processing space S2 is purged with the first gas G1, and the third gas G3 is removed from the processing space S2. As shown in FIG. 13, the purging of the processing space S2 continues for a time period t12. The time period t12 is, for example, 5 seconds.

[0117] After purging the processing space S2, the control device MC controls the high-frequency power supply 30 of the plasma generation unit 11 to supply power to the antenna 20, thereby generating a plasma PL of the first gas G1 in the plasma generation space S1. Electrons in the plasma PL receive energy from the electric field E generated in the processing space S2, are accelerated, and are irradiated onto the substrate W as the electron beam 60. The surface of the substrate W is activated by irradiating the substrate W with the electron beam 60. As shown in FIG. 13 , the irradiation of the electron beam 60 continues for a time period t13. The time period t13 is, for example, 3 seconds. The pressure in the processing space S2 during irradiation with the electron beam 60 is set to, for example, a pressure Pr0 lower than the pressure Pr1.

[0118] After the irradiation of the electron beam 60 is stopped, the control device MC controls the exhaust device 44 to change the pressure in the processing space S2 to pressure Pr3, which is higher than pressure Pr2. As a result, the first gas G1 moves from the plasma generation space S1 to the processing space S2 in an unionized state, and the substrate W is exposed to the first gas G1. When the substrate W is exposed to the first gas G1, which is an inert gas, the negative charge accumulated on the substrate W is removed. As shown in FIG. 13, the removal of the negative charge on the substrate W continues for a time period t14. The time period t14 is, for example, 5 seconds.

[0119] After the time period t4 has elapsed, the control device MC controls the second gas supply unit 14 to supply the second gas G2 to the processing space S2. The second gas G2 contains ozone (O3) as a reactant. When the ozone is supplied to the processing space S2, a chemical reaction occurs between the disilane deposited on the substrate W and the ozone, thereby forming a SiO2 film on the substrate W. As shown in FIG. 13, the supply of the second gas G2 continues for a time period t15. The time period t15 is, for example, 2 seconds. The pressure in the processing space S2 during the supply of the second gas G2 is set to, for example, a pressure Pr2.

[0120] After the supply of the second gas G2 is stopped, the control device MC controls the exhaust device 44 to change the pressure of the processing space S2 from pressure Pr2 to pressure Pr1. As a result, the processing space S2 is purged with the first gas G1, and the second gas G2 is removed from the processing space S2. As shown in FIG. 13, the purging of the processing space S2 continues for a time period t16. The time period t16 is, for example, 5 seconds.

[0121] By repeating the above-mentioned sequence including supplying the third gas G3, purging the third gas G3, irradiating the electron beam 60, removing the negative charge from the substrate W, supplying the second gas, and purging the second gas, a SiO2 film is formed on the silicon substrate W.

[0122] Although various exemplary embodiments have been described above, the present invention is not limited to the above-described exemplary embodiments, and various omissions, substitutions, and modifications may be made. Furthermore, elements in different embodiments may be combined to form other embodiments.

[0123] For example, although the substrate processing apparatus 1 is an inductively coupled plasma processing apparatus, the substrate processing apparatus 1 according to another embodiment may be a plasma processing apparatus of another type. Furthermore, the method MT may be performed using any type of plasma processing apparatus other than the substrate processing apparatus 1. For example, the plasma generated in the plasma generation space S1 by the plasma generation unit 11 may be capacitively coupled plasma (CCP), inductively coupled plasma (ICP), electron-cyclotron-resonance plasma (ECR plasma), helicon wave plasma (HWP), or surface wave plasma (SWP). Various types of plasma generation units 11, including alternating current (AC) plasma generation units and direct current (DC) plasma generation units, may be used. Plasma excitation methods based on electrodeless discharge, such as inductively coupled plasma and surface wave plasma, in which no electrodes are inserted into the plasma, allow for the electrical circuitry to be configured independently of the electrical circuitry of the energy supply unit, improving the flexibility of the device configuration.

[0124] In the substrate processing apparatus 1, 1A, the second gas G2 and the third gas G3 are supplied to the processing space S2 through the plurality of gas discharge holes 16c formed in the second mesh member 16, but the supply paths of the second gas G2 and the third gas G3 do not necessarily have to be formed in the second mesh member 16. For example, the supply paths of the second gas G2 and the third gas G3 may be formed in the first mesh member 15, or the second gas G2 and the third gas G3 may be supplied through the sidewall 102 of the processing vessel 10.

[0125] The steps of method MT may be performed simultaneously or in any order, unless inconsistent. The methods described in this disclosure present various steps using an exemplary order and are not limited to the particular order presented.

[0126] Furthermore, in the above-described embodiment, a method for forming a film on the substrate W while irradiating the substrate W with electrons has been described, but it is not necessary to form a film on the substrate W. For example, the substrate processing method may be a method for modifying the surface of the substrate W by removing charge from the substrate W after irradiating the substrate W with electrons.

[0127] In the substrate processing apparatus 1, 1A, a DC voltage Vc1 is applied between the first mesh member 15 and the second mesh member 16, and a pulse voltage Vp is applied between the second mesh member 16 and the ground potential, but in one embodiment, a variable DC power supply may be disposed between the first mesh member 15 and the second mesh member 16 to apply a pulse voltage, and a DC power supply may be disposed between the second mesh member 16 and the ground potential to apply the DC voltage Vc1. Alternatively, a pulsed voltage may be applied between the first mesh member 15 and the second mesh member 16 and between the second mesh member 16 and the ground potential.

[0128] 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.

[0129] [1] A substrate processing method for processing a substrate supported by a substrate support in a processing vessel defining an internal space including a first space and a second space, generating plasma of a first gas in the first space; applying a potential lower than a potential of the substrate support to a mesh member disposed between the first space and the second space, the mesh member having a plurality of through holes for selectively transmitting electrons in the plasma generated in the first space to the second space, and irradiating the substrate disposed in the second space with the electrons that have transmitted through the mesh member; after stopping the generation of the plasma, exposing the substrate to the first gas to remove negative charges that have been charged on the substrate by irradiating the electrons; A substrate processing method comprising:

[0130] [2] The substrate processing method according to [1], wherein the pressure in the second space during the step of removing the negative charges is higher than the pressure in the second space during the step of irradiating the electrons.

[0131] [3] The substrate processing method according to [1] or [2], further comprising the step of supplying a second gas to the second space after the step of removing the negative charge.

[0132] [4] the first gas comprises argon; The substrate processing method according to [3], wherein the second gas contains vinylsilane.

[0133] [5] The substrate processing method according to [3] or [4], further comprising the step of supplying a third gas to the second space before the step of removing the negative charge.

[0134] [6] the first gas comprises argon; the second gas comprises ozone; The substrate processing method according to [5], wherein the third gas contains disilane.

[0135] [7] During the step of irradiating the electrons, a pulse voltage that periodically varies between a first voltage level and a second voltage level is applied to the mesh member; The substrate processing method according to any one of [1] to [6], wherein the first voltage level is a voltage level for accelerating the electrons so that their kinetic energy becomes lower than the ionization energy of the first gas, and the second voltage level is a voltage level for accelerating the electrons so that their kinetic energy becomes higher than the ionization energy of the first gas.

[0136] [8] the first gas comprises argon; [7] The substrate processing method according to [7], wherein the first voltage level is a voltage level for accelerating the electrons so that their kinetic energy becomes lower than 15.8 eV, and the second voltage level is a voltage level for accelerating the electrons so that their kinetic energy becomes higher than 15.8 eV.

[0137] [9] The first gas includes helium; [7] The substrate processing method according to [7], wherein the first voltage level is a voltage level for accelerating the electrons so that their kinetic energy becomes lower than 24.6 eV, and the second voltage level is a voltage level for accelerating the electrons so that their kinetic energy becomes higher than 24.6 eV. Contains argon,

[0138]

[10] The substrate processing method according to any one of [7] to [9], wherein the pulse voltage has a pulse width and a duty ratio that do not ignite plasma of the first gas in the second space.

[0139]

[11] A processing vessel defining an interior space including a first space and a second space; a first gas supply unit configured to supply a first gas to the first space; a plasma generating unit configured to generate plasma of the first gas in the first space; a substrate support disposed in the second space and configured to support a substrate thereon; a mesh member disposed between the first space and the second space, the mesh member having a plurality of through holes for selectively transmitting electrons in the plasma generated in the first space to the second space; an energy supply unit that applies a voltage to the mesh member to supply energy to the electrons in the second space; a control device; Equipped with The control device generating plasma of a first gas in the first space; applying a potential to the mesh member that is lower than a potential of the substrate support, and irradiating the substrate disposed in the second space with the electrons that have passed through the mesh member; after stopping the generation of the plasma, exposing the substrate to the first gas to remove negative charges that have been charged on the substrate by irradiating the electrons; The first gas supply unit, the plasma generation unit, and the energy supply unit are controlled so that the above-mentioned Substrate processing equipment.

[0140]

[12] Further comprising an exhaust device configured to reduce the pressure in the internal space; The substrate processing apparatus according to

[11] , wherein the control device controls the exhaust device so that the pressure in the second space during the process of removing the negative charge is higher than the pressure in the second space during the process of irradiating the electrons.

[0141]

[13] Further comprising a second gas supply unit configured to supply a second gas to the second space; The substrate processing apparatus according to

[11] or

[12] , wherein the control device controls the second gas supply unit so that a second gas is supplied to the second space after negative charges on the substrate are removed.

[0142]

[14] The substrate processing apparatus according to any one of

[11] to

[13] , further comprising an ion collector electrode provided in the first space and configured to collect ions in the plasma.

[0143]

[15] The substrate processing apparatus according to

[14] , wherein the energy supply unit applies a potential to the ion collector electrode that is lower than a potential of the mesh member.

[0144]

[16] The energy supply unit applies a pulse voltage that periodically varies between a first voltage level and a second voltage level to the mesh member, The substrate processing apparatus according to any one of

[11] to

[15] , wherein the first voltage level is a voltage level for accelerating the electrons so that their kinetic energy becomes lower than the ionization energy of the first gas, and the second voltage level is a voltage level for accelerating the electrons so that their kinetic energy becomes higher than the ionization energy of the first gas.

[0145]

[17] the first gas comprises argon;

[16] The substrate processing apparatus according to

[16] , wherein the first voltage level is a voltage level for accelerating the electrons so that their kinetic energy becomes lower than 15.8 eV, and the second voltage level is a voltage level for accelerating the electrons so that their kinetic energy becomes higher than 15.8 eV.

[0146]

[18] the first gas comprises helium;

[16] The substrate processing apparatus according to

[16] , wherein the first voltage level is a voltage level for accelerating the electrons so that their kinetic energy becomes lower than 24.6 eV, and the second voltage level is a voltage level for accelerating the electrons so that their kinetic energy becomes higher than 24.6 eV.

[0147]

[19] The substrate processing apparatus according to any one of

[16] to

[18] , wherein the pulse voltage has a pulse width and a duty ratio that do not ignite plasma of the first gas in the second space.

[0148]

[20] The device further includes a second mesh member separate from the first mesh member, the second mesh member is disposed between the first mesh member and the substrate support; The energy supply unit is a first DC power source that applies a voltage to the first mesh member so that the potential of the first mesh member is lower than the potential of the second mesh member; a second DC power supply that applies a voltage to the second mesh member so that the potential of the second mesh member is lower than the potential of the substrate support; Including, The substrate processing apparatus according to any one of

[11] to

[19] , wherein at least one of the first DC power supply and the second DC power supply is a variable DC power supply that generates a pulsed voltage. [Explanation of symbols]

[0149] 1, 1A...substrate processing apparatus, 10...processing vessel, 10s...internal space, 11...plasma generation section, 12...substrate support, 13...first gas supply section, 14...second gas supply section, 15...first mesh member, 15h...through-hole, 16...second mesh member, 17...energy supply section, 44...exhaust device, 50...variable DC power supply, 80...ion collector electrode, D...duty ratio, G1...first gas, G2...second gas, G3...third gas, MC...control device, PL...plasma, S1...plasma generation space (first space), S2...processing space (second space), V1...first voltage level, V2...second voltage level, Vion...ionization voltage, Vt...pulse voltage, W...substrate.

Claims

1. 1. A substrate processing method for processing a substrate supported by a substrate support in a processing vessel defining an interior space including a first space and a second space, comprising: generating plasma of a first gas in the first space; applying a potential lower than a potential of the substrate support to a mesh member disposed between the first space and the second space, the mesh member having a plurality of through holes for selectively transmitting electrons in the plasma generated in the first space to the second space, and irradiating the substrate disposed in the second space with the electrons that have transmitted through the mesh member; after stopping the generation of the plasma, exposing the substrate to the first gas to remove negative charges that have been charged on the substrate by irradiating the electrons; A substrate processing method comprising:

2. 2. The substrate processing method according to claim 1, wherein the pressure in the second space during the step of removing the negative charges is higher than the pressure in the second space during the step of irradiating the electrons.

3. 2. The substrate processing method according to claim 1, further comprising the step of supplying a second gas to the second space after the step of removing the negative charge.

4. the first gas comprises argon; The method of claim 3 , wherein the second gas comprises vinylsilane.

5. The substrate processing method according to claim 3 , further comprising the step of supplying a third gas to the second space before the step of removing the negative charges.

6. the first gas comprises argon; the second gas includes ozone; The substrate processing method of claim 5 , wherein the third gas includes disilane.

7. applying a pulse voltage that periodically varies between a first voltage level and a second voltage level to the mesh member during the step of irradiating the electrons; 2. The substrate processing method of claim 1, wherein the first voltage level is a voltage level for accelerating the electrons so that their kinetic energy becomes lower than the ionization energy of the first gas, and the second voltage level is a voltage level for accelerating the electrons so that their kinetic energy becomes higher than the ionization energy of the first gas.

8. the first gas comprises argon; 8. The substrate processing method of claim 7, wherein the first voltage level is a voltage level for accelerating the electrons so that their kinetic energy becomes lower than 15.8 eV, and the second voltage level is a voltage level for accelerating the electrons so that their kinetic energy becomes higher than 15.8 eV.

9. the first gas comprises helium; 8. The substrate processing method of claim 7, wherein the first voltage level is a voltage level for accelerating the electrons so that their kinetic energy becomes lower than 24.6 eV, and the second voltage level is a voltage level for accelerating the electrons so that their kinetic energy becomes higher than 24.6 eV. Contains argon,

10. 8. The substrate processing method according to claim 7, wherein the pulse voltage has a pulse width and a duty ratio that do not ignite plasma of the first gas in the second space.

11. a processing vessel defining an interior space including a first space and a second space; a first gas supply unit configured to supply a first gas to the first space; a plasma generating unit configured to generate plasma of the first gas in the first space; a substrate support disposed in the second space and configured to support a substrate thereon; a mesh member disposed between the first space and the second space, the mesh member having a plurality of through holes for selectively transmitting electrons in the plasma generated in the first space to the second space; an energy supply unit that applies a voltage to the mesh member to supply energy to the electrons in the second space; a control device; Equipped with The control device generating plasma of a first gas in the first space; applying a potential to the mesh member that is lower than a potential of the substrate support, and irradiating the substrate disposed in the second space with the electrons that have passed through the mesh member; after stopping the generation of the plasma, exposing the substrate to the first gas to remove negative charges that have been charged on the substrate by irradiating the electrons; The plasma generating unit is configured to control the first gas supply unit, the plasma generating unit, and the energy supply unit so that the above-mentioned Substrate processing equipment.

12. further comprising an exhaust device configured to reduce the pressure in the interior space; 12. The substrate processing apparatus according to claim 11, wherein the control device controls the exhaust device so that the pressure in the second space during the step of removing the negative charge is higher than the pressure in the second space during the step of irradiating the electrons.

13. a second gas supply unit configured to supply a second gas to the second space; The substrate processing apparatus according to claim 11 , wherein the control device controls the second gas supply unit so that the second gas is supplied to the second space after negative charges on the substrate are removed.

14. The substrate processing apparatus according to claim 11 , further comprising an ion collector electrode provided in the first space and configured to collect ions in the plasma.

15. The substrate processing apparatus according to claim 14 , wherein the energy supply unit applies a potential to the ion collector electrode that is lower than a potential of the mesh member.

16. the energy supply unit applies a pulse voltage that periodically fluctuates between a first voltage level and a second voltage level to the mesh member; 12. The substrate processing apparatus of claim 11, wherein the first voltage level is a voltage level for accelerating the electrons so that their kinetic energy becomes lower than the ionization energy of the first gas, and the second voltage level is a voltage level for accelerating the electrons so that their kinetic energy becomes higher than the ionization energy of the first gas.

17. the first gas comprises argon; 17. The substrate processing apparatus of claim 16, wherein the first voltage level is a voltage level for accelerating the electrons so that their kinetic energy becomes lower than 15.8 eV, and the second voltage level is a voltage level for accelerating the electrons so that their kinetic energy becomes higher than 15.8 eV.

18. the first gas comprises helium; 17. The substrate processing apparatus of claim 16, wherein the first voltage level is a voltage level for accelerating the electrons so that their kinetic energy becomes lower than 24.6 eV, and the second voltage level is a voltage level for accelerating the electrons so that their kinetic energy becomes higher than 24.6 eV.

19. The substrate processing apparatus according to claim 16, wherein the pulse voltage has a pulse width and a duty ratio that do not ignite plasma of the first gas in the second space.

20. The mesh member further includes a second mesh member separate from the first mesh member, the second mesh member is disposed between the first mesh member and the substrate support; The energy supply unit is a first DC power source that applies a voltage to the first mesh member so that the potential of the first mesh member is lower than the potential of the second mesh member; a second DC power supply that applies a voltage to the second mesh member so that the potential of the second mesh member is lower than the potential of the substrate support; Including, The substrate processing apparatus according to claim 11 , wherein at least one of the first DC power supply and the second DC power supply is a variable DC power supply that generates a pulsed voltage.

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