Substrate processing method and substrate processing device

Abstract

Provided is a substrate processing method for processing a substrate in a processing space including a first space and a second space. This substrate processing method comprises: a step for generating plasma of a first gas in a first space; a step for supplying a second gas to a second space; a step for transferring electrons in the plasma from the first space to the second space; a step for generating an electron beam by supplying, to the electrons, energy lower than the energy for ionizing atoms of the second gas, and generating radicals from the second gas by irradiating the second gas with the electron beam; and a step for processing a substrate using the radicals.

Description

Substrate processing method and substrate processing apparatus

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

[0002] Highly active radicals are used in various substrate surface treatments such as film formation, cleaning, defect repair, and hydrophobic treatment of semiconductor substrates. For example, Patent Document 1 listed below describes a technology in which a catalyst is irradiated with an electron beam while a gas is being supplied to generate gaseous radicals, and the radicals are reacted with deposits to decompose and remove the deposits.

[0003] Patent Document 2 listed below describes a technique for depositing and growing silicon on a substrate by irradiating a gas containing hydrogen gas with an electron beam to generate gas plasma in a chamber, passing a silicon vapor flow through the plasma, and then supplying the silicon vapor flow to the substrate surface. In this technique, the silicon vapor flow is passed through the plasma, and silicon molecules or silicon clusters in the silicon vapor flow are reduced by hydrogen radicals in the plasma, thereby improving the quality of the silicon film deposited on the substrate.

[0004] JP 2012-151304 A JP 2001-332497 A

[0005] When a gas plasma is generated as in the technology described in Patent Document 2, positively charged ions are generated in the plasma. These ions are accelerated by the potential difference relative to the plasma and collide with the substrate. This can cause physical damage (ion irradiation damage) to the film-forming surface of the substrate, deteriorating the quality of the substrate film.

[0006] Therefore, there is a need to provide a substrate processing method and a substrate processing apparatus that can process a substrate using radicals while suppressing damage to the substrate.

[0007] In one exemplary embodiment, a substrate processing method for processing a substrate in a processing space including a first space and a second space is provided, the substrate processing method includes the steps of generating plasma of a first gas in the first space, supplying a second gas to the second space, transferring electrons in the plasma from the first space to the second space, supplying energy to the electrons so that the electron energy is lower than the energy required to ionize the second gas to generate an electron beam, irradiating the second gas with the electron beam to generate radicals from the second gas, and processing the substrate using the radicals.

[0008] According to one exemplary embodiment, it becomes possible to process a substrate using radicals while suppressing damage to the substrate.

[0009] FIG. 1 is a diagram schematically illustrating a substrate processing apparatus according to an exemplary embodiment; FIG. 2 is a top view schematically illustrating an exemplary first partition; FIG. 3 is a diagram illustrating an example of the movement of charged particles within an opening of the first partition; FIG. 4 is a diagram illustrating a reaction that occurs when electrons collide with hydrogen atoms (radicals) or hydrogen molecules, and the electron energy threshold at which the reaction occurs; FIG. 5 is a diagram illustrating an example of the movement of charged particles within an opening of the first partition; FIG. 6 is a plan view illustrating an opening of the exemplary first partition; and FIG. 7 is a graph illustrating simulation results of ion and electron transmittance. FIG. 7 is a diagram schematically illustrating a substrate processing apparatus according to another exemplary embodiment; and FIG. 8 is a top view schematically illustrating an exemplary first partition. (a) shows an exemplary LC parallel resonant circuit, and (b) shows an exemplary LC low-pass filter. FIG. 8 is a flowchart illustrating a substrate processing method according to an exemplary embodiment.

[0010] Various exemplary embodiments are described below.

[0011] In one exemplary embodiment, a substrate processing method for processing a substrate in a processing space including a first space and a second space is provided, the substrate processing method includes the steps of generating plasma of a first gas in the first space, supplying a second gas to the second space, transferring electrons in the plasma from the first space to the second space, supplying energy to the electrons so that the electron energy is lower than the energy required to ionize the second gas to generate an electron beam, irradiating the second gas with the electron beam to generate radicals from the second gas, and processing the substrate using the radicals.

[0012] In the substrate processing method according to the above embodiment, energy is supplied to electrons that have moved from the first space to the second space to generate an electron beam, and the electron beam is then irradiated onto the second gas. Here, if the electron energy required to dissociate the molecules of the second gas and generate radicals is lower than the electron energy required to ionize the second gas, the electron beam energy can be set lower than the energy required to ionize the second gas, thereby generating radicals from the second gas without ionizing the second gas. By using the radicals generated in this manner, the substrate can be appropriately processed while suppressing physical damage to the substrate caused by ions.

[0013] In one exemplary embodiment, in the step of generating radicals, energy may be supplied to the electrons so that the energy of the electrons is higher than a threshold energy for exciting ground-state radicals generated from the second gas. Excited-state radicals can be generated by irradiating atoms of the second gas with an electron beam of electrons having energy higher than the threshold energy for exciting ground-state radicals generated from the second gas. Because excited-state radicals have higher activity than ground-state radicals, the use of excited-state radicals allows for efficient processing of substrates.

[0014] In one exemplary embodiment, the first gas may be a noble gas.

[0015] In one exemplary embodiment, the second gas may be hydrogen gas.

[0016] In one exemplary embodiment, in the step of generating radicals, energy may be supplied to electrons so that their energy is 8.8 eV or more and 13.8 eV or less. The electron energy threshold for dissociating hydrogen molecules to generate hydrogen radicals is 8.8 eV. On the other hand, the electron energy threshold for ionizing hydrogen radicals is 13.8 eV. The electron energy threshold for dissociating hydrogen molecules is even higher, at 15.4 eV (ionization of hydrogen molecules) or 15.6 eV (dissociation and ionization of hydrogen molecules). Therefore, by generating an electron beam having an energy of 8.8 eV or more and 13.8 eV or less and irradiating the electron beam onto hydrogen gas, it is possible to selectively generate hydrogen radicals while suppressing the generation of hydrogen ions.

[0017] In one exemplary embodiment, in the step of generating radicals, energy may be supplied to the electrons so that their energy is 10.2 eV or more and 13.8 eV or less. The electron energy threshold for exciting hydrogen atoms is 10.2 eV. By irradiating hydrogen gas with an electron beam having an energy of 10.2 eV or more and 13.8 eV or less, highly active excited hydrogen radicals can be generated while suppressing the generation of hydrogen ions.

[0018] In one exemplary embodiment, the processing vessel includes a first portion defining a first space and a second portion electrically insulated from the first portion and defining a second space. The step of transferring electrons from the first space to the second space may further include applying a negative voltage to a partition wall having a plurality of openings and dividing the internal space into the first space and the second space, and to the first portion with respect to the second portion. Applying a negative voltage to the partition wall dividing the first space and the second space generates an attractive force between positively charged ions and the partition wall. Due to this attractive force, ions in the plasma generated in the first space are attracted to the first partition wall, collide with the first partition wall, lose their charge, and return to an electrically neutral gas. Meanwhile, a repulsive force acts between negatively charged electrons and the first partition wall. Therefore, electrons in the plasma generated in the first space transfer from the first space to the second space through the plurality of openings without colliding with the first partition wall. Therefore, electrons in the plasma can be selectively transferred from the first space to the second space.

[0019] According to one exemplary embodiment, the substrate processing method may further include applying a potential lower than the potential of the partition wall to an ion collector electrode disposed in the first space to draw ions in the plasma to the ion collector electrode. By drawing ions in the plasma to the ion collector electrode, the plasma is prevented from being excessively positively charged. As a result, it is possible to prevent the movement of electrons from the first space to the second space from being inhibited.

[0020] According to another exemplary embodiment, a substrate processing apparatus includes a processing vessel defining an internal space, a first partition wall dividing the internal space into a first space and a second space, a first gas supply unit configured to supply a first gas to the first space, a second gas supply unit configured to supply a second gas to the second space, a plasma generation unit configured to generate plasma of the first gas in the first space, a substrate support provided in the second space, and an energy supply unit, wherein the first partition wall is configured to selectively transmit electrons in the plasma generated in the first space to the second space, and the energy supply unit supplies energy to electrons in the second space to generate an electron beam such that the energy of the electrons is lower than the energy required to ionize the second gas, and irradiates the second gas with the electron beam to generate radicals from the second gas for substrate processing.

[0021] In the substrate processing apparatus according to the above embodiment, the energy supply unit supplies energy to the electrons that have moved from the first space to the second space so that the energy of the electrons is lower than the energy required to ionize atoms of the second gas. Therefore, radicals can be generated without ionizing the second gas. By using the radicals generated in this manner, the substrate can be appropriately processed while suppressing physical damage to the substrate caused by ions.

[0022] In one exemplary embodiment, the energy supplier may supply energy to the electrons so that the energy of the electrons is higher than a threshold energy that excites ground-state radicals generated from the second gas.

[0023] In one exemplary embodiment, the first gas may be a noble gas.

[0024] In one exemplary embodiment, the second gas may be hydrogen gas.

[0025] In one exemplary embodiment, the energy supplier may supply energy to the electrons so that the energy of the electrons is equal to or greater than 8.8 eV and equal to or less than 13.8 eV.

[0026] In one exemplary embodiment, the energy supplier may supply energy to the electrons so that the energy of the electrons is equal to or greater than 10.2 eV and equal to or less than 13.8 eV.

[0027] In one exemplary embodiment, the plasma generating device may have a plurality of openings communicating the first space and the second space, and the opening width of the openings may be equal to or less than twice the thickness of a sheath formed between the plasma and the first partition wall. By setting the opening width of the openings equal to or less than twice the thickness of the sheath, positively charged ions are accelerated by the sheath electric field and collide with the first partition wall, resulting in their disappearance. Therefore, the ions are restricted from passing through the first partition wall. On the other hand, negatively charged electrons are not attracted to the first partition wall by the sheath voltage and can pass through the openings. Therefore, by setting the opening width of the openings equal to or less than twice the thickness of the sheath, electrons in the plasma can be selectively extracted.

[0028] According to one exemplary embodiment, the substrate processing apparatus may further include a second partition disposed between the first partition and the substrate support, and the energy supply unit may be configured to apply a voltage between the first partition and the second partition such that the potential of the first partition is lower than the potential of the second partition. By relatively increasing the potential of the second partition, electrons that have moved to the second space receive energy according to the potential difference between the first partition and the second partition and are accelerated. This generates an electron beam having a predetermined energy.

[0029] In one exemplary embodiment, the second partition has a plurality of openings that allow radicals to pass through, and the opening width of each opening of the first partition may be smaller than the opening width of each opening of the second partition.

[0030] According to an exemplary embodiment, the substrate processing apparatus may further include an ion collector electrode provided in the first space and having a potential lower than that of the first partition. By drawing ions in the plasma into the ion collector electrode, the plasma can be prevented from being excessively positively charged. As a result, the movement of electrons from the first space to the second space can be prevented from being impeded.

[0031] In one exemplary embodiment, the ion collector electrode may have a honeycomb shape with a plurality of through holes penetrating the thickness of the ion collector electrode, which allows ions in the plasma to be efficiently drawn into the ion collector electrode.

[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] 1 is a diagram schematically illustrating a substrate processing apparatus according to an exemplary embodiment. The substrate processing apparatus 1 is an apparatus for generating radicals and processing a substrate using the radicals. In this specification, a radical refers to an electrically neutral atom or molecule having an unpaired electron.

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

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

[0036] The processing vessel 10 includes an upper vessel portion (first portion) 10A and a lower vessel portion (second portion) 10B. The upper vessel portion 10A is supported on the lower vessel portion 10B via an insulating member 18. The insulating member 18 is provided on the lower vessel portion 10B and is made of an insulating material. The insulating member 18 is made of ceramic, such as quartz. The upper vessel portion 10A defines an upper space (first space) S1 therein for generating plasma. The lower vessel portion 10B defines a lower space (second space) S2 therein for processing a substrate. That is, the internal space 10s includes the upper space S1 and the lower space S2.

[0037] The lower vessel part 10B is electrically grounded. A passage 10p is formed in the sidewall of the lower vessel part 10B. 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 lower vessel part 10B to open and close the passage 10p.

[0038] The plasma generating unit 11 includes an upper electrode 20. The upper electrode 20 closes the upper opening of the processing vessel 10 together with an insulating member 21. The insulating member 21 has insulating properties. The upper electrode 20 is supported on the upper vessel upper part 10A via the insulating member 21.

[0039] In one embodiment, the upper electrode 20 includes a top plate 22 and a support 23. The lower surface of the top plate 22 defines the internal space 10s. The top plate 22 has a plurality of gas discharge holes 22a formed therein. Each of the plurality of gas discharge holes 22a penetrates the top plate 22 in the thickness direction (vertical direction). The top plate 22 is made of, for example, silicon. The top plate 22 may have a structure in which a plasma-resistant film is provided on the surface of an aluminum member. This film may be a ceramic film, such as a film formed by anodizing or a film formed from yttrium oxide.

[0040] The support 23 detachably supports the top plate 22. The support 23 is made of a conductive material such as aluminum. A first gas diffusion chamber 23a is formed inside the support 23. A plurality of gas holes 23b extend downward from the first gas diffusion chamber 23a. The plurality of gas holes 23b are respectively connected to the plurality of gas discharge holes 22a. A first gas introduction port 23c is formed in the support 23. The first gas introduction port 23c is connected to the first gas diffusion chamber 23a.

[0041] A first gas supply pipe 24 is connected to the first gas introduction port 23c. A first gas supply unit 13 is connected to the first gas supply pipe 24. 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 first gas supply pipe 24. 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 first gas supply pipe 24 via the valve 25 and the flow rate controller 26. The gas source 27 supplies the first gas G1 to the first gas supply pipe 24 via the valve 25 and the flow rate controller 26.

[0042] The first gas G1 is a gas for generating plasma. For example, the first gas G1 includes a rare gas such as argon gas (Ar), krypton gas (Kr), or xenon gas (Xe). The first gas G1 may be hydrogen gas or a mixed gas containing a rare gas and hydrogen gas. The first gas G1 supplied from the first gas supply unit 13 is supplied to the upper space S1 via the first gas supply pipe 24, the first gas diffusion chamber 23a, the plurality of gas holes 23b, and the plurality of gas discharge holes 22a. As described above, the first gas supply unit 13 can supply the first gas G1 to the upper space S1 at a regulated flow rate.

[0043] The plasma generation unit 11 further includes a power supply 30. The power supply 30 is connected to the upper electrode 20 via a matching box 31 and generates power for plasma generation. The power supply 30 supplies high-frequency power having a frequency within a range of, for example, 400 kHz to 100 MHz, for example, a frequency of 400 kHz or 13.56 MHz, to the upper electrode 20. The matching box 31 has a matching circuit for matching the output impedance of the power supply 30 with the impedance of the load side (upper electrode 20). The matching circuit of the matching box 31 may include a capacitor.

[0044] When power is supplied from the power supply 30 to the upper electrode 20, the first gas G1 is excited in the upper 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, when the first gas G1 is argon gas, the plasma PL contains positive argon ions and negative electrons.

[0045] The substrate support 12 is provided in the lower space S2 and is configured to support the substrate W placed thereon. The substrate W has a substantially disk shape.

[0046] 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 generally disk-like 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. The heat exchange medium may be a liquid refrigerant or a refrigerant (e.g., chlorofluorocarbon) that cools the lower electrode 41 by vaporizing. A heat exchange medium circulation device (e.g., a chiller unit) is connected to the flow path 41f. This circulation device is provided 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.

[0047] In one embodiment, the substrate processing apparatus 1 may further include a power supply unit 45. The power supply unit 45 is configured to generate a DC voltage to be applied to the lower electrode 41. The power supply unit 45 is electrically connected to the lower electrode 41. In one embodiment, the power supply unit 45 supplies a negative DC voltage and a positive DC voltage to the lower electrode 41 via a low-pass filter 46.

[0048] The electrostatic chuck 42 is provided on the lower electrode 41. When the substrate W is processed in the lower 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.

[0049] 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 placed on the substrate mounting region of the electrostatic chuck 42. The focus ring FR is made of, for example, silicon or silicon carbide.

[0050] 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.

[0051] 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 of the vessel lower portion 10B. 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.

[0052] The first partition 15 is provided in the processing vessel 10 and is disposed between the upper space S1 and the lower space S2. That is, the first partition 15 divides the internal space 10s into the upper space S1 and the lower space S2. The upper space S1 is formed between the first partition 15 and the upper electrode 20. The lower space S2 is formed between the substrate support 12 and the first partition 15. In one embodiment, the first partition 15 is formed in a disk shape and is made of a metal such as stainless steel or aluminum. The surface of the first partition 15 may be covered with a dielectric. The first partition 15 is electrically connected to the vessel upper portion 10A.

[0053] FIG. 2 is a top view schematically illustrating an exemplary first partition wall 15. As shown in FIG. 2, the first partition wall 15 has an outer peripheral portion 51 and a lattice portion 52. The outer peripheral portion 51 is formed in an annular shape. The lattice portion 52 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 51. The lattice portion 52 of the first partition wall 15 has a plurality of openings 15h that penetrate the first partition wall 15 in the thickness direction. The plurality of openings 15h are through-holes that communicate between the upper space S1 and the lower space S2. The plurality of openings 15h have an opening width that blocks ions in the plasma PL generated in the upper space S1 and allows electrons in the plasma PL to pass from the upper space S1 to the lower space S2.

[0054] The opening width of each of the openings 15h refers to the width of the opening formed in the first partition wall 15 by each of the openings 15h. For example, if the opening 15h has a circular planar shape, the diameter of the circular shape is defined as the opening width of each of the openings 15h. If the opening has a regular polygonal planar shape, the diameter of a circle inscribed in the regular polygonal opening is defined as the opening width of each of the openings 15h. The first partition wall 15 shown in FIG. 2 has a plurality of openings 15h, each of which has a substantially square planar shape.

[0055] As shown in FIG. 2 , a second gas diffusion chamber 15a is provided inside the first partition wall 15. The second gas diffusion chamber 15a extends in an annular shape along the outer periphery 51 of the first partition wall 15. A lattice-shaped gas passage 15b is connected to the second gas diffusion chamber 15a. The lattice-shaped gas passage 15b is formed inside the lattice portion 52. The lattice portion 52 has a plurality of gas discharge holes 15c formed therein (see FIG. 1 ), which communicate with the gas passage 15b and open toward the lower space S2 (electron extraction space S21, described later). The gas discharge holes 15c extend obliquely downward (toward the substrate support 12) with respect to the axis AX. The gas discharge holes 15c communicate with the second gas diffusion chamber 15a via the gas passage 15b.

[0056] A second gas introduction port 53 is connected to the second gas diffusion chamber 15a. A second gas supply pipe 54 is connected to the second gas introduction port 53. A second gas supply unit 14 is connected to the second gas supply pipe 54. The second gas supply unit 14 includes a valve 55, a flow rate controller 56, and a gas source 57. The valve 55 has a function of switching between supplying and stopping the gas supply to the second gas supply pipe 54. The flow rate controller 56 is a mass flow controller or a pressure-controlled flow rate controller. The gas source 57 is connected to the second gas supply pipe 54 via the valve 55 and the flow rate controller 56. The gas source 57 supplies the second gas G2 to the second gas supply pipe 54 via the valve 55 and the flow rate controller 56.

[0057] The second gas G2 is a source gas for generating radicals for substrate processing. The second gas G2 is, for example, hydrogen gas (H ２ ), nitrogen gas (N ２ ), oxygen gas (O ２ ), ammonia gas (NH ３ ) or a mixed gas thereof. The second gas G2 supplied from the second gas supply unit 14 is supplied to the lower space S2 via the second gas supply pipe 54, the second gas diffusion chamber 15a, the gas passage 15b, and the plurality of gas discharge holes 15c. As described above, the second gas supply unit 14 can supply the second gas G2 to the lower space S2 at a regulated flow rate.

[0058] In one embodiment, the processing vessel 10 further includes a second partition 17. The second partition 17 is disposed between the first partition 15 and the substrate support 12 and divides the lower space S2 into an electron extraction space S21 and a processing space S22. That is, the lower space S2 includes the electron extraction space S21 and the processing space S22. The electron extraction space S21 is formed between the first partition 15 and the second partition 17. The processing space S22 is formed between the substrate support 12 and the second partition 17. The substrate W is disposed in the processing space S22.

[0059] In one embodiment, the second partition 17 is formed in a disk shape and is made of a metal such as stainless steel or aluminum. The surface of the second partition 17 may be coated with a radical-resistant film or may be conductive. The second partition 17 is supported by and electrically connected to the container lower portion 10B. Therefore, the second partition 17 is electrically grounded via the container lower portion 10B.

[0060] The second partition 17 has a mesh structure, a honeycomb structure, or a multi-hole structure. That is, the second partition 17 has a plurality of openings 17h formed therein, penetrating in the thickness direction of the second partition 17. Each opening 17h extends parallel to the axis AX and is a through-hole that communicates between the electron extraction space S21 and the processing space S22.

[0061] The opening width of each of the openings 17h refers to the width of the opening formed in the second partition wall 17 by each of the openings 17h. For example, if the planar shape of each opening 17h is circular, the diameter of the circular opening is defined as the opening width of each of the openings 17h. If the planar shape of each opening 17h 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 openings 17h. In one embodiment, the opening width of each of the openings 15h in the first partition wall 15 may be smaller than the opening width of each of the openings 17h in the second partition wall 17.

[0062] The energy supply unit 16 includes a DC power supply 50. The DC power supply 50 is configured to generate a voltage for supplying energy to electrons that have passed through the multiple openings 15h of the first partition 15. The positive electrode of the DC power supply 50 is electrically grounded. The negative electrode of the DC power supply 50 is electrically connected to the power supply 30 and supplies a negative bias voltage to the power supply 30. The negative electrode of the DC power supply 50 is also electrically connected to the first partition 15 via the upper vessel portion 10A. Therefore, the potential of the first partition 15 is equal to the potential of the upper vessel portion 10A. The DC power supply 50 generates a potential difference (voltage Ve) between the first partition 15 and the second partition 17 so that the potential of the first partition 15 is lower than the potential of the second partition 17. That is, a negative voltage Ve is applied to the upper vessel portion 10A and the first partition 15 relative to the lower vessel portion 10B. As a result, an electric field E is formed between the first partition 15 and the second partition 17, that is, in the electron extraction space S21, from the second partition 17 to the first partition 15 (see FIG. 4).

[0063] The movement of charged particles in the plasma PL will be described with reference to Figures 3 and 4. In Figures 3 and 4, a circle surrounding a "+", a circle surrounding a "-", a circle surrounding a "*", and a circle surrounding a "*" represent positive ions, electrons, and radicals, respectively.

[0064] As shown in Fig. 3, the plasma PL of the first gas G1 generated in the upper space S1 contains positive ions and electrons. As described above, the first partition 15 has a negative potential relative to the potential of the plasma PL, so an attractive force acts between the positively charged positive ions and the first partition 15. This attractive force causes the positive ions to be attracted to the first partition 15, as shown in Fig. 3, and collide with the first partition 15, thereby losing their charge and returning to an electrically neutral gas. Therefore, the first partition 15 has the function of blocking the movement of positive ions in the plasma PL from the upper space S1 to the lower space S2 (electron extraction space S21).

[0065] On the other hand, a repulsive force acts between negatively charged electrons and the first partition 15. Therefore, as shown in Fig. 3, electrons in the plasma PL move from the upper space S1 to the lower space S2 through the multiple openings 15h without colliding with the first partition 15. In other words, the first partition 15 has the function of selectively transmitting electrons out of the positive ions and electrons in the plasma PL.

[0066] As shown in FIG. 4 , electrons passing through the multiple openings 15 h of the first partition 15 receive energy from the electric field E formed in the electron extraction space S21 and are accelerated. As a result, an electron beam 60 is formed in the electron extraction space S21. This electron beam 60 is irradiated onto the second gas G2 supplied to the electron extraction space S21 through the multiple gas ejection holes 15 c. As a result, the electrons constituting the electron beam 60 collide with molecules of the second gas G2, dissociating the molecules and generating radicals. The substrate W placed in the processing space S22 is processed by the radicals generated in the electron extraction space S21. Meanwhile, the electrons constituting the electron beam 60 are attracted to the second partition 17, which has a relatively high potential, and are collected.

[0067] Here, when the electron beam 60 is irradiated onto the second gas G2, the reaction occurring in the molecules or atoms of the second gas G2 varies depending on the energy of the electron beam 60. For example, if excessive energy is supplied to the molecules of the second gas G2 by irradiation with the electron beam 60, plasma of the second gas G2 is formed in the electron extraction space S21. Once plasma is generated in the electron extraction space S21, it easily diffuses into the processing space S22. 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. To avoid such damage, the energy supplier 16 supplies energy to the electrons so that the electron energy is lower than the energy required to ionize the atoms of the second gas G2.

[0068] Figure 5 shows the reactions that occur when electrons collide with hydrogen molecules or hydrogen atoms (radicals), as well as the electron energy threshold at which these reactions occur. As shown in Figure 5, when hydrogen molecules are irradiated with electrons having an energy of 8.8 eV or more, the hydrogen molecules dissociate and hydrogen radicals are generated. Hydrogen radicals are electrically neutral hydrogen atoms with one unpaired electron. On the other hand, when hydrogen radicals are irradiated with electrons having an energy of 13.6 eV or more, the hydrogen radicals are ionized and hydrogen ions are generated.

[0069] When hydrogen ions are formed in the lower space S2 (electron extraction space S21), the hydrogen ions are accelerated by the potential difference between the plasma PL and the substrate W and collide with the substrate W. As a result, physical damage may occur to the substrate W. Therefore, the DC power supply 50 supplies energy to the electrons to generate the electron beam 60 so that the energy of the electrons is higher than the energy that dissociates the second gas G2 and lower than the energy that ionizes atoms of the second gas G2.

[0070] For example, when the second gas G2 is hydrogen gas, the voltage Ve is set to 8.8 V or more and 13.6 V or less when the energy (initial energy) of the electrons immediately after moving to the lower space S2 is approximately zero. By setting the voltage Ve to 8.8 V or more and 13.6 V or less, the energy of the electrons in the electron extraction space S21 becomes 8.8 eV or more and 13.6 eV or less. By colliding these electrons with atoms of the second gas G2, hydrogen radicals can be selectively generated without generating hydrogen ions. Note that if the electrons immediately after moving to the lower space S2 have initial energy, the sum of the initial energy and the energy supplied to the electrons becomes the final energy of the electrons in the lower space S2. For example, when the initial energy of the electrons is 1 eV, setting the voltage Ve to 7.8 V or more and 12.6 V or less will result in the electron energy becoming 8.8 eV or more and 13.6 eV or less.

[0071] In one embodiment, the energy supplier 16 may supply energy to the electrons so that the energy of the electrons is higher than a threshold energy at which ground-state radicals generated from the second gas G2 are excited. Since excited-state radicals have higher activity than ground-state radicals, the substrate W can be processed with higher reactivity by using the excited-state radicals.

[0072] For example, as shown in Figure 5, when electron energy of 10.2 eV or more is supplied to hydrogen atoms (hydrogen radicals), the hydrogen radicals transition from the ground state to an excited state. Therefore, when the second gas G2 is hydrogen gas, in order to generate excited hydrogen radicals, the voltage Ve can be set to 10.2 V or more and 13.6 V or less when the initial energy of the electrons is approximately zero. In this case, the energy of the electrons in the electron extraction space S21 is set to 10.2 eV or more and 13.6 eV or less. By irradiating the second gas G2 with electrons having such energy, excited hydrogen radicals can be generated.

[0073] The substrate processing apparatus 1 may further include a controller MC. The controller 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 controller 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 controller MC, a process specified by the recipe data is executed in the substrate processing apparatus 1. Etching methods according to various embodiments can be executed in the substrate processing apparatus 1 under the control of each part of the substrate processing apparatus 1 by the controller MC.

[0074] Next, the opening width of each opening 15h in the first partition wall 15 will be described in more detail. As described above, the openings 15h have opening widths that block ions in the plasma PL generated in the upper space S1 and selectively transmit electrons in the plasma PL from the upper space S1 to the lower space S2. Specifically, to selectively transmit electrons, the opening width a of each opening 15h may be less than twice the thickness d of a sheath 70 (hereinafter referred to as the "sheath thickness") formed between the plasma PL and the first partition wall 15 (see FIG. 6). The sheath 70 is a potential barrier formed between the plasma PL and the first partition wall 15 due to the difference in mobility between electrons and ions.

[0075] The sheath thickness d is given by the following formula (1).

[0076]

[0077] V in formula (1) ０ [V] is the potential difference between the plasma PL and the first partition wall 15, and T ｅ [eV] is the electron temperature of the plasma PL. Ｄ [mm] is the Debye length, which is given by the following formula (2).

[0078] n in formula (2) ｅ [cm －３ ] is the electron density of the plasma PL. Based on equations (1) and (2), the sheath thickness [mm] is given by the following equation (3).

[0079]

[0080] 3, ions that reach the inside of the sheath 70 are accelerated by the sheath electric field and collide with the first partition 15, where they are annihilated. On the other hand, a repulsive force is generated between the electrons and the first partition 15, so the electrons pass through the multiple openings 15h without being attracted to the first partition 15. In other words, positively charged ions cannot pass through the sheath 70, but negatively charged electrons can pass through the sheath 70.

[0081] 6, when the opening width a of each opening 15h is equal to or less than twice the sheath thickness d, a sheath 70 is formed over the entire opening 15h, preventing ions in the plasma PL from leaking into the electron extraction space S21. Meanwhile, electrons in the plasma PL are subjected to electrostatic force from the electric field E and are extracted into the electron extraction space S21 through the sheath 70. That is, by setting the opening width a of each opening 15h equal to or less than twice the sheath thickness d, it is possible to block ions in the plasma PL and selectively move electrons in the plasma PL from the upper space S1 to the lower space S2.

[0082] The amount of plasma that can pass through the opening 15h is shown below. The ratio of the amount of plasma that has passed through the opening 15h to the amount of plasma before passing through is called the transmittance T ＴＲ The geometric aperture ratio of the opening 15h when viewed from above is defined as aperture ratio T ＯＰ The rate at which light disappears on the side wall of the opening 15h before reaching the surface opposite the opening 15h is defined as the transmission rate T ＰＳ In this case, the transmittance T ＴＲ =Aperture ratio T ＯＰ × Passage rate T ＰＳ It can be expressed as: Transmittance T ＴＲ indicates the ratio of ions or electrons that pass through the opening 15h and move to the electron extraction space S21 among the ions or electrons in the upper space S1.

[0083] 7 is a plan view showing the opening 15h of the first partition wall 15. The opening region 40 shown in FIG. 6 indicates the region along the center line of the lattice portion 52 surrounding the opening 15h. As described above, positively charged ions cannot pass through the sheath 70, so the ion aperture ratio T ＯＰ is expressed as the ratio of the area of ​​the non-sheath region 72 where the sheath 70 is not formed to the area of ​​the opening region 40 (including the lattice unit region). On the other hand, since electrons having a negative charge can pass through the sheath 70, the electron aperture ratio T ＯＰ is expressed as the ratio of the area of ​​the opening 15h to the area of ​​the opening region 40.

[0084] When the opening width of the opening 15h is a and the thickness of the lattice portion 52 defining the opening 15h is h, the transmittance T ＰＳ is given by the following formula (4): In the case of ions, a in formula (4) is replaced with a−2×sheath thickness d, that is, the length of one side of the non-sheath region 72.

[0085]

[0086] FIG. 8 shows the transmittance T of ions and electrons under the following simulation conditions: ＴＲ The simulation results are shown in Fig. 8. １ indicates the electron density directly below the lattice portion 52.

[0087] (Simulation conditions) Electron temperature Te of plasma PL: 3 [eV] Potential difference V between plasma PL and first partition wall 15 ０ : 35 [V] Electron density ne directly above the lattice portion 52 ０ :1 x e １０ [cm －３ ] Sheath thickness d: 0.83 [mm] Lattice width w of lattice portion 52: 1.2 [mm] Thickness h of lattice portion 52: 0.5 [mm]

[0088] Under the above simulation conditions, as shown in FIG. 8, when the opening width of the opening 15h is set to 1.66 mm, the ion transmittance T ＴＲ becomes almost zero, and the electron transmittance becomes about 16%. That is, by making the opening width a of the opening 15h twice the sheath thickness d, the electron transmittance becomes 1.6×e9 [cm －３ ] can be selectively transmitted.

[0089] As described above, in the substrate processing apparatus 1 according to the above embodiment, energy is supplied to electrons that have passed through the opening 15h of the first partition 15 and moved to the electron extraction space S21 to generate the electron beam 60, and the electron beam 60 is irradiated onto the second gas G2. Here, the electron energy required to dissociate the molecules of the second gas to generate radicals is smaller than the electron energy required to ionize the atoms of the second gas G2. Therefore, by supplying electrons with energy lower than the energy required to ionize the atoms of the second gas G2, radicals can be generated without ionizing the atoms of the second gas G2. Therefore, the substrate W can be processed using the generated radicals while suppressing physical damage to the substrate W caused by ions.

[0090] Next, a substrate processing apparatus according to another embodiment will be described. Fig. 9 is a cross-sectional view 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.

[0091] As shown in FIG. 9 , the substrate processing apparatus 1A includes a first partition 15A instead of the first partition 15. FIG. 10 is a top view schematically illustrating an exemplary first partition 15A. As shown in FIG. 10 , the first partition 15A includes an insulating plate 151 and a lattice portion 152. The insulating plate 151 is made of an insulator such as quartz and is formed in a substantially disk shape. The insulating plate 151 has one or more through holes 151h penetrating the insulating plate 151 in the thickness direction. The lattice portion 152 is provided inside each of the one or more through holes 151h. The lattice portion 152 has a mesh structure, a honeycomb structure, or a multi-hole structure and is connected to the insulating plate 151. The lattice portion 152 of the first partition 15A has a plurality of openings 152h penetrating the lattice portion 152 in the thickness direction. The plurality of openings 152h are through holes that connect the upper space S1 and the lower space S2. The plurality of openings 152h have an opening width that blocks ions in the plasma PL generated in the upper space S1 and allows electrons in the plasma PL to pass from the upper space S1 to the lower space S2.

[0092] The lattice portion 152 of the first partition wall 15A is electrically connected to the negative electrode of the DC power supply 50 via a wiring WR. The lattice portion 152 may also be electrically connected to the upper portion 10A of the container via the wiring WR. The wiring WR may be covered with an insulator such as quartz.

[0093] The substrate processing apparatus 1A further includes an ion collector electrode 80. The ion collector electrode 80 is disposed between the first partition wall 15A and the upper electrode 20, and is provided in the upper space S1. The ion collector electrode 80 has a generally 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 its thickness direction.

[0094] The energy supply unit 16 of the substrate processing apparatus 1A further includes a DC power supply 81 in addition to the DC power supply 50. The negative electrode of the DC power supply 50 is coupled to the vessel upper portion 10A, the first partition 15A, and the plasma generation power supply 30. The DC power supply 81 is connected in series with the DC power supply 50. More specifically, the positive electrode of the DC power supply 81 is electrically coupled to the negative electrode of the DC power supply 81. The negative electrode of the DC power supply 81 is electrically coupled to the ion collector electrode 80. The DC power supply 81 generates a potential difference (voltage Vc) between the ion collector electrode 80 and the first partition 15A so that the potential of the ion collector electrode 80 is lower than the potential of the first partition 15A. The voltage Vc is, for example, 10 V to 100 V. That is, a negative potential is applied to the ion collector electrode 80 relative to the potential of the first partition 15A. Therefore, the potentials of the ion collector electrode 80, the first partition 15A, and the second partition 17 increase in this order.

[0095] 9 , in the substrate processing apparatus 1A, a second gas diffusion chamber 15 a, a gas passage 15 b, and a plurality of gas ejection holes 15 c are formed in the second partition wall 17. The second gas G2 supplied from the second gas supply unit 14 is injected from the plurality of gas ejection holes 15 c via the second gas supply pipe 54, the second gas diffusion chamber 15 a, and the gas passage 15 b. The plurality of gas ejection holes 15 c extend obliquely upward (toward the first partition wall 15) with respect to the axis AX, and supply the second gas G2 supplied from the second gas supply unit 14 to the electron extraction space S21.

[0096] The second gas G2 supplied to the electron extraction space S21 is irradiated with the electron beam 60, and radicals are generated from the second gas G2. The substrate W placed in the processing space S22 is processed by the radicals generated in the electron extraction space S21.

[0097] If electrons are continuously extracted from the plasma PL into the electron extraction space S21 to generate the electron beam 60, the potential of the plasma PL may tend to lean toward a positive polarity, resulting in a decrease in electron extraction efficiency. In contrast, in the substrate processing apparatus 1A, an ion collector electrode 80 to which a negative potential is applied is disposed in the upper 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 increasing the electron extraction efficiency.

[0098] The surface area of ​​the ion collector electrode 80 may be larger than the surface area of ​​the first partition 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 partition 15. By making the surface area of ​​the ion collector electrode 80 larger than the surface area of ​​the first partition 15, ions flow into the ion collector electrode 80 and electrons are attracted to the first partition 15. In other words, a non-ambipolar diffusion flow is formed, and ions in the plasma PL can be efficiently attracted.

[0099] In one embodiment, the inner wall surface of the upper vessel portion 10A may be covered with an insulator 19. The insulator 19 is made of, for example, quartz. If the potential of the side wall of the upper space S1 becomes higher than the potential of the first partition wall 15, electrons in the plasma PL may easily reach the side wall of the upper space S1, which may reduce the electron extraction efficiency. In response to this, covering the inner wall surface of the upper vessel portion 10A with the insulator 19 can suppress the reduction in electron extraction efficiency.

[0100] In one embodiment, the substrate processing apparatus 1A may further include an RF filter 82. The RF filter 82 is provided between the ion collector electrode 80 and the DC power supply 81. If the ion collector electrode 80 is disposed within the plasma PL, RF (radio frequency) power is supplied to the wiring connecting the ion collector electrode 80 and the DC power supply 81, which may damage the DC power supply 81, generate noise due to RF power leakage, or reduce the efficiency of excitation of the plasma PL. By providing the RF filter 82 between the ion collector electrode 80 and the DC power supply 81 and blocking the RF power, the occurrence of these problems can be suppressed.

[0101] The RF filter 82 may be, for example, an LC parallel resonant circuit as shown in FIG. 11( a). The LC parallel resonant circuit has an extremely large impedance at the resonant frequency f0, so it can selectively pass frequencies other than the resonant frequency f0. For example, by adjusting the inductance (L) and capacitance (C) of the LC parallel resonant circuit to match the resonant frequency f0 with the frequency of the plasma excitation power, it is possible to prevent RF power from leaking to the DC power supply 81 side while allowing ions that have flowed into the ion collector electrode 80 to flow as DC current. The resonant frequency f0 of the LC parallel resonant circuit is given by the following equation (5):

[0102]

[0103] The RF filter 82 may be, for example, an LC low-pass filter as shown in FIG. 11B. The LC low-pass filter is capable of cutting off frequencies higher than the cutoff frequency f1 and passing frequencies lower than the cutoff frequency f1. By setting the cutoff frequency f1 lower than the frequency of the plasma excitation power, it is possible to prevent RF power from leaking to the DC power supply 81 side, while allowing ions that have flowed into the ion collector electrode 80 to flow as DC current. The cutoff frequency f1 of the LC low-pass filter is given by the following equation (6):

[0104]

[0105] A substrate processing method according to one exemplary embodiment will be described below with reference to Fig. 12. Fig. 12 is a flowchart showing the substrate processing method according to one exemplary embodiment. The substrate processing method MT shown in Fig. 12 is performed using the substrate processing apparatus 1 or 1A described above.

[0106] 12 , in the substrate processing method MT, a substrate W is first placed on a substrate support 12 (step ST1). Next, a first gas G1 is supplied from a first gas supply unit 13 to the upper space S1 (step ST2). The first gas G1 is, for example, a rare gas such as argon gas (Ar). The first gas G1 may be continuously supplied to the upper space S1 during the execution of the substrate processing method MT.

[0107] Next, the second gas G2 is supplied from the second gas supply unit 14 to the electron extraction space S21 (step ST3). The second gas G2 is, for example, hydrogen gas. The second gas G2 may be continuously supplied to the electron extraction space S21 during the execution of the substrate processing method MT.

[0108] Next, power is supplied from the power supply 30 to the upper electrode 20, and a plasma PL of the first gas G1 is generated in the upper space S1 (step ST4). The power may be continuously supplied from the power supply 30 to the upper electrode 20 during execution of the substrate processing method MT.

[0109] In one embodiment, in order to attract positively charged ions in the plasma PL to the ion collector electrode 80 disposed in the upper space S1, a negative voltage Vc is applied from the DC power supply 81 to the ion collector electrode 80 (step ST5). At this time, the DC power supply 81 applies the voltage Vc between the first partition 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 partition 15. For example, the voltage Vc is set to 10 V. By applying a negative potential to the ion collector electrode 80 with respect to the first partition 15, the ions in the plasma PL generated in the upper space S1 are attracted to and captured by the ion collector electrode 80.

[0110] Next, in order to move negatively charged electrons in the plasma PL from the upper space S1 to the electron extraction space S21, the DC power supply 50 applies a voltage Ve between the first partition 15 and the second partition 17 so that the potential of the first partition 15 is lower than the potential of the second partition 17 (step ST6). That is, when DC voltages are applied from the DC power supplies 50 and 81 to the first partition 15, the second partition 17, and the ion collector electrode 80, the potential of the first partition 15 becomes higher than the potential of the ion collector electrode 80 and lower than the potential of the second partition 17. As a result, electrons in the plasma PL are attracted to the second partition 17, which has a relatively high potential, and move to the electron extraction space S21. That is, electrons in the plasma PL are selectively extracted to the electron extraction space S21.

[0111] At this time, the voltage Ve is set to a voltage that supplies energy to the electrons so that the electron energy is higher than the energy required to dissociate the molecules of the second gas G2 but lower than the energy required to ionize the second gas G2. For example, when the initial energy of the electrons is approximately zero and the second gas G2 is hydrogen gas, the voltage Ve is set to 8.8 V or more and 13.6 V or less. By applying the voltage Ve of 8.8 V or more and 13.6 V or less between the first partition 15 and the second partition 17, an electron beam 60 having an energy of 8.8 eV or more and 13.6 eV or less is generated in the electron extraction space S21.

[0112] Next, the generated electron beam 60 is irradiated onto the second gas G2 to generate radicals from the second gas G2 (step ST7). For example, if the second gas G2 is hydrogen gas, the electron beam 60 collides with hydrogen molecules, dissociating the hydrogen molecules and generating hydrogen radicals. At this time, the electrons are supplied with energy lower than the energy required to ionize the second gas G2. Therefore, irradiation with the electron beam 60 does not generate plasma (ionization) of the second gas G2, and instead, radicals are selectively generated.

[0113] Next, the substrate W placed in the processing space S22 is exposed to the radicals and processed (step ST8). At this time, since no plasma of the second gas G2 is generated in the lower space S2, it is possible to prevent ions from colliding with the substrate W and causing damage to the substrate W.

[0114] In one embodiment, in step ST6, the voltage Ve applied between the first partition 15 and the second partition 17 may be set to a voltage that supplies energy to the electrons so that the electron energy is higher than the threshold energy required to excite ground-state radicals generated from the second gas G2. For example, when the initial energy of the electrons is approximately zero and the second gas G2 is hydrogen gas, the voltage Ve is set to 10.2 V or more and 13.6 V or less. By applying a voltage Ve of 10.2 V or more and 13.6 V or less between the first partition 15 and the second partition 17, an electron beam 60 having an electron energy of 10.2 eV or more and 13.6 eV or less is generated. By irradiating the second gas G2 with this electron beam 60, hydrogen radicals transition from the ground state to an excited state, generating highly reactive excited-state hydrogen radicals. By using these excited-state hydrogen radicals, the substrate W can be processed more efficiently.

[0115] As described above, in the substrate processing method MT, energy is supplied to electrons that have moved from the upper space S1 to the lower space S2 to generate the electron beam 60, and the electron beam 60 is irradiated onto the second gas G2. Here, the electron energy required to dissociate the molecules of the second gas G2 and generate radicals is lower than the electron energy required to ionize the atoms of the second gas G2. Therefore, by supplying electrons with energy lower than the energy required to ionize the atoms of the second gas G2, radicals can be generated without ionizing the atoms of the second gas G2. Therefore, according to the substrate processing method MT, it is possible to process the substrate W using radicals while suppressing physical damage to the substrate W caused by ions.

[0116] It should be noted that step ST5 does not necessarily have to be performed in the substrate processing method MT. Even if ions are not attracted to the ion collector electrode 80, radicals can be generated without ionizing atoms of the second gas G2, thereby suppressing damage to the substrate W during substrate processing.

[0117] 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.

[0118] For example, although the substrate processing apparatus 1 is a capacitively coupled plasma processing apparatus, the substrate processing apparatus 1 according to another embodiment may be a plasma processing apparatus of another type. Furthermore, the substrate processing method MT may be performed using any type of plasma processing apparatus other than the substrate processing apparatus 1. For example, the plasma formed in the upper space S1 by the plasma generating unit 11 may be capacitively coupled plasma (CCP), inductively coupled plasma (ICP), electron-cyclotron-resonance plasma (ECR plasma), helicon wave plasma (HWP), surface wave plasma (SWP), or the like. Also, various types of plasma generating units 11, including alternating current (AC) plasma generating units and direct current (DC) plasma generating units, may be used. If the plasma excitation method is an electrodeless discharge method in which electrodes are not inserted into the plasma, such as inductively coupled plasma or surface wave plasma, it becomes possible to configure an electric circuit independently of the electric circuit system of the energy supply unit, improving the degree of freedom in the device configuration.

[0119] In one embodiment, the substrate processing apparatus 1 does not need to include the second partition 17. Even if the substrate processing apparatus 1 does not include the second partition 17, electrons in the plasma PL move to the electron extraction space S21 due to the potential difference between the plasma PL and the substrate W. The electrons that have moved to the electron extraction space S21 are accelerated by the voltage Ve supplied from the DC power supply 50 and are irradiated onto the substrate W. In this case, the voltage of the substrate W temporarily fluctuates due to the irradiation of electrons, but once the potential of the substrate W becomes constant due to the emission of secondary electrons from the substrate W, the substrate W can be processed.

[0120] 1 and 9, the second gas G2 is supplied to the electron extracting space S21 from a plurality of gas discharge holes 15c formed in the first partition 15 or the second partition 17. However, the supply path of the second gas G2 does not necessarily have to be formed in the first partition 15 or the second partition 17. For example, the second gas G2 may be supplied through the sidewall of the lower portion 10B of the container.

[0121] The steps of the substrate processing method MT may be performed simultaneously or in any order, unless inconsistent. The methods described in this disclosure present the various steps using an exemplary order and are not limited to the particular order presented.

[0122] 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.

[0123] [1] A substrate processing method for processing a substrate in a processing vessel defining an internal space including a first space and a second space, the substrate processing method comprising: generating plasma of a first gas in the first space; supplying a second gas to the second space; moving electrons in the plasma from the first space to the second space; generating an electron beam by supplying energy to the electrons so that the energy of the electrons is lower than the energy that ionizes the second gas, and irradiating the second gas with the electron beam to generate radicals from the second gas; and processing the substrate using the radicals.

[0124] [2] The substrate processing method according to [1], wherein in the step of generating radicals, energy is supplied to the electrons so that the energy of the electrons is higher than a threshold energy that excites ground-state radicals generated from the second gas.

[0125] [3] The substrate processing method according to [1] or [2], wherein the first gas contains a rare gas.

[0126] [4] The substrate processing method according to any one of [1] to [3], wherein the second gas contains hydrogen gas.

[0127] [5] The substrate processing method according to [4], wherein in the step of generating radicals, energy is supplied to the electrons so that their energy is 8.8 eV or more and 13.8 eV or less.

[0128] [6] The substrate processing method according to [4] or [5], wherein in the step of generating radicals, energy is supplied to the electrons so that their energy is 10.2 eV or more and 13.8 eV or less.

[0129] [7] The substrate processing method according to any one of [1] to [6], wherein the processing vessel includes a first portion that defines the first space and a second portion that is electrically insulated from the first portion and defines the second space, and the step of moving the electrons from the first space to the second space further includes the step of applying a negative voltage to the first portion and a partition wall that has a plurality of openings and that divides the internal space into the first space and the second space.

[0130] [8] The substrate processing method according to any one of [1] to [7], further comprising the step of applying a potential lower than a potential of the first partition to an ion collector electrode disposed in the first space, thereby attracting ions in the plasma to the ion collector electrode.

[0131] a first partition wall dividing the internal space into a first space and a second space; a first gas supply unit configured to supply a first gas to the first space; a second gas supply unit configured to supply a second gas to the second space; a plasma generation unit configured to generate plasma of the first gas in the first space; a substrate support provided in the second space; and an energy supply unit, wherein the first partition wall is configured to selectively transmit electrons in the plasma generated in the first space to the second space, and the energy supply unit supplies energy to the electrons in the second space to generate an electron beam such that the energy of the electrons is lower than the energy that ionizes the second gas, and irradiates the second gas with the electron beam to generate radicals for substrate processing from the second gas.

[0132]

[10] The substrate processing apparatus according to [9], wherein the energy supplying unit supplies energy to the electrons so that the energy of the electrons is higher than a threshold energy that excites ground-state radicals generated from the second gas.

[0133]

[11] The substrate processing apparatus according to [9] or

[10] , wherein the first gas contains a rare gas.

[0134]

[12] The substrate processing apparatus according to any one of [9] to

[11] , wherein the second gas contains hydrogen gas.

[0135]

[13] The substrate processing apparatus according to

[12] , wherein the energy supplying unit supplies energy to the electrons so that the energy of the electrons is 8.8 eV or more and 13.8 eV or less.

[0136]

[14] The substrate processing apparatus according to

[12] or

[13] , wherein the energy supplying unit supplies energy to the electrons so that the energy of the electrons is 10.2 eV or more and 13.8 eV or less.

[0137]

[15] The substrate processing apparatus according to any one of [9] to

[14] , wherein the first partition has a plurality of openings that communicate with the first space and the second space, and the opening width of the openings is not more than twice the thickness of a sheath formed between the plasma and the first partition.

[0138]

[16] The substrate processing apparatus according to any one of [9] to

[15] , further comprising a second partition disposed between the first partition and the substrate support, wherein the energy supply unit is configured to apply a voltage between the first partition and the second partition so that a potential of the first partition is lower than a potential of the second partition.

[0139]

[17] The substrate processing apparatus according to

[16] , wherein the second partition has a plurality of openings that allow the radicals to pass through, and the opening width of each of the openings in the first partition is smaller than the opening width of each of the openings in the second partition.

[0140]

[18] The substrate processing apparatus according to any one of [9] to

[17] , further comprising an ion collector electrode provided in the first space and having a potential lower than a potential of the first partition wall.

[0141]

[19] The substrate processing apparatus according to

[18] , wherein the ion collector electrode has a honeycomb shape with a plurality of through-holes penetrating the ion collector electrode in the thickness direction thereof.

[0142] 1, 1A...substrate processing apparatus, 10...processing vessel, 10A...upper vessel (first part), 10B...lower vessel (second part), 10s...internal space, 11...plasma generation section, 12...substrate support, 13...first gas supply section, 14...second gas supply section, 15, 15A...first partition wall, 15h, 152h...openings of first partition wall, 16...energy supply section, 17...second partition wall, 17h...respective openings of second partition wall, 60...electron beam, 70...sheath, 80...ion collector electrode, 80p...through hole, G1...first gas, G2...second gas, MT...substrate processing method, PL...plasma, S1...upper space (first space), S2...lower space (second space), W...substrate.

Claims

1. A substrate processing method for processing a substrate in a processing vessel defining an internal space including a first space and a second space, comprising: generating plasma of a first gas in the first space; supplying a second gas to the second space; moving electrons in the plasma from the first space to the second space; generating an electron beam by supplying energy to the electrons so that the energy of the electrons is lower than the energy that ionizes the second gas, and irradiating the second gas with the electron beam to generate radicals from the second gas; and processing the substrate using the radicals.

2. A substrate processing method as described in claim 1, wherein in the step of generating radicals, energy is supplied to the electrons so that the energy of the electrons is higher than the threshold energy that excites ground-state radicals generated from the second gas.

3. The substrate processing method of claim 1, wherein the first gas comprises a noble gas.

4. The substrate processing method of claim 1, wherein the second gas comprises hydrogen gas.

5. The substrate processing method according to claim 4, wherein in the step of generating radicals, energy is supplied to the electrons so that their energy is 8.8 eV or more and 13.8 eV or less.

6. The substrate processing method according to claim 4, wherein in the step of generating radicals, energy is supplied to the electrons so that their energy is 10.2 eV or more and 13.8 eV or less.

7. The substrate processing method of claim 1, wherein the processing vessel includes a first portion defining the first space and a second portion electrically insulated from the first portion and defining the second space, and the step of moving the electrons from the first space to the second space further includes the step of applying a negative voltage to the first portion and a partition wall having a plurality of openings that divides the internal space into the first space and the second space.

8. The substrate processing method according to claim 7, further comprising the step of applying a potential lower than the potential of said partition to an ion collector electrode disposed in said first space, thereby attracting ions in said plasma to said ion collector electrode.

9. A substrate processing apparatus comprising: a processing vessel defining an internal space; a first partition dividing the internal space into a first space and a second space; a first gas supply unit configured to supply a first gas to the first space; a second gas supply unit configured to supply a second gas to the second space; a plasma generation unit configured to generate plasma of the first gas in the first space; a substrate support provided in the second space; and an energy supply unit, wherein the first partition is configured to selectively transmit electrons in the plasma generated in the first space to the second space, and the energy supply unit supplies energy to the electrons in the second space to generate an electron beam such that the energy of the electrons is lower than the energy that ionizes the second gas, and irradiates the second gas with the electron beam to generate radicals for substrate processing from the second gas.

10. The substrate processing apparatus according to claim 9, wherein the energy supplying unit supplies energy to the electrons so that the energy of the electrons is higher than a threshold energy that excites ground-state radicals generated from the second gas.

11. The substrate processing apparatus of claim 9, wherein the first gas comprises a noble gas.

12. The substrate processing apparatus of claim 9, wherein the second gas comprises hydrogen gas.

13. The substrate processing apparatus according to claim 12, wherein the energy supplying unit supplies energy to the electrons so that the energy of the electrons is 8.8 eV or more and 13.8 eV or less.

14. The substrate processing apparatus according to claim 12, wherein the energy supplying unit supplies energy to the electrons so that the energy of the electrons is 10.2 eV or more and 13.8 eV or less.

15. A substrate processing apparatus as described in claim 9, wherein the first partition has a plurality of openings that connect the first space and the second space, and the opening width of the openings is not more than twice the thickness of a sheath formed between the plasma and the first partition.

16. The substrate processing apparatus according to claim 9, further comprising a second partition disposed between the first partition and the substrate support, wherein the energy supply unit is configured to apply a voltage between the first partition and the second partition so that the potential of the first partition is lower than the potential of the second partition.

17. The substrate processing apparatus according to claim 16, wherein the second partition has a plurality of openings that allow the radicals to pass through, and the opening width of each of the openings in the first partition is smaller than the opening width of each of the openings in the second partition.

18. The substrate processing apparatus according to claim 9, further comprising an ion collector electrode provided in the first space and having a potential lower than a potential of the first partition wall.

19. The substrate processing apparatus according to claim 18, wherein the ion collector electrode has a honeycomb shape with a plurality of through-holes penetrating the ion collector electrode in the thickness direction thereof.

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