Plasma source device, substrate processing apparatus, and control method

Abstract

Provided are a plasma source device that suppresses damage to a gas supply path, a substrate processing apparatus, and a control method.　This plasma source device comprises a gas supply path to which a processing gas is supplied from a gas supply unit and which has an internal flow path through which the processing gas flows, and a plasma generation unit that magnetically excites the processing gas in the gas supply path to generate plasma, wherein the plasma generation unit has: a dielectric core that surrounds the gas supply path; and a helical resonance antenna that is wound around the dielectric core along the gas supply path, and one end of which is connected to power supply wiring to which high-frequency power is supplied from a high-frequency power source and ground wiring to be installed, and the other end of which is open.

Description

Plasma source device, substrate processing device, and control method

[0001] This disclosure relates to a plasma source device, a substrate processing device, and a control method.

[0002] Patent Document 1 discloses a plasma processing apparatus that generates plasma using a helical antenna.

[0003] Japanese Patent Publication No. 2021-77451

[0004] In one aspect, this disclosure provides a plasma source device, a substrate processing device, and a control method that suppress damage to the gas supply path.

[0005] To solve the above problems, according to one embodiment, a plasma source device is provided comprising: a gas supply path having an internal flow path through which a processing gas is supplied from a gas supply unit; and a plasma generation unit that generates plasma by magnetically exciting the processing gas in the gas supply path, wherein the plasma generation unit comprises a dielectric core surrounding the gas supply path and a helical resonant antenna wound around the dielectric core along the gas supply path, one end of which is connected to a power supply wiring that receives high-frequency power from a high-frequency power supply and to an installed grounding wiring, and the other end which is open.

[0006] In one aspect, this disclosure can provide a plasma source device, a substrate processing device, and a control method that suppress damage to the gas supply path.

[0007] An example of a schematic diagram showing the configuration of a substrate processing apparatus. An example of a perspective view of a plasma source apparatus. An example of a perspective view of a plasma source apparatus seen through a shield. An example of a perspective view with a dielectric core cut. An example of a cross-sectional view of a plasma source apparatus. An example of another cross-sectional view of a plasma source apparatus. A diagram showing an example of the electromagnetic field distribution of a plasma source apparatus. An example of a graph showing the relationship between high-frequency power frequency and reflectivity. Electron density n ０ and plasma absorption power P ａｂｓ An example of a graph showing the relationship between the frequency f of high-frequency power and the plasma skin depth δ. ｃ An example of a graph showing the relationship.

[0008] The following describes embodiments for implementing this disclosure with reference to the drawings. In each drawing, the same reference numerals are used for identical components, and redundant explanations may be omitted.

[0009] [Substrate Processing Apparatus] An example of the substrate processing apparatus 1 will be explained using Figure 1. Figure 1 is an example of a schematic diagram showing an example of the configuration of the substrate processing apparatus 1. The substrate processing apparatus 1 is a device that, for example, supplies remote plasma into a processing container 2 under reduced pressure to perform a desired process (film deposition, etching, cleaning, etc.).

[0010] The substrate processing apparatus 1 includes a processing container 2, a mounting table 3, an exhaust unit 4, a plasma source device 5, a gas supply unit 6, a high-frequency power supply 7, and a control unit 8.

[0011] The processing container 2 houses the mounting table 3 and forms a processing space 2s inside it. The mounting table 3 supports the substrate W to be processed. The exhaust unit 4 is connected to a gas outlet 2e provided in the processing container 2 and exhausts the gas inside the processing container 2. The exhaust unit 4 also has a pressure regulating valve, a vacuum pump, etc., to adjust the pressure inside the processing space 2s.

[0012] The plasma source device 5 is a device that receives processing gas from the gas supply unit 6 and high-frequency power for plasma generation from the high-frequency power supply 7 to generate inductively coupled plasma (ICP) of the processing gas, and supplies the generated plasma of the processing gas to the processing space 2s in the processing container 2. Details of the plasma source device 5 will be described later with reference to Figure 2, etc.

[0013] The gas supply unit 6 includes a gas supply source 61 for storing the processed gas and a flow rate controller 62. The gas supply unit 6 supplies the processed gas, whose flow rate has been adjusted by the flow rate controller 62, to the gas supply path 51 of the plasma source device 5 (see Figure 3, etc., described later).

[0014] The high-frequency power supply 7 supplies high-frequency power for plasma generation to the helical resonant antenna 53 of the plasma source device 5 (see Figure 3, etc., described later).

[0015] The control unit 8 is, for example, a computer and includes a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), auxiliary storage device, etc. The CPU operates based on a program stored in the ROM or auxiliary storage device and controls the operation of the substrate processing device 1. The control unit 8 may be located inside or outside the substrate processing device 1. If the control unit 8 is located outside the substrate processing device 1, the control unit 8 can control the substrate processing device 1 by communication means such as wired or wireless.

[0016] For example, the control unit 8 adjusts the processing space 2s to a predetermined pressure by controlling the exhaust unit 4 (pressure regulating valve, vacuum pump). The control unit 8 also supplies the plasma of the processing gas from the plasma source device 5 to the processing space 2s by controlling the flow rate controller 62 and the high-frequency power supply 7 of the gas supply unit 6.

[0017] The plasma source device 5 supplies a plasma (remote plasma) of a processing gas to the processing space 2s for performing a desired treatment (film deposition, etching, etc.) on the substrate W. However, the plasma source device 5 is not limited to this; for example, it also supplies a plasma (remote plasma) of a cleaning gas to the processing space 2s for cleaning the inside of the processing container 2.

[0018] [Plasma Source Device 5] Next, the plasma source device 5 will be described using Figures 2 to 6. Figure 2 is an example of a perspective view of the plasma source device 5. Figure 3 is an example of a perspective view of the plasma source device 5 after passing through the shield 54. Figure 4 is an example of a perspective view of the dielectric core 52 cut in half. Figure 5 is an example of a cross-sectional view of the plasma source device 5. Figure 6 is an example of another cross-sectional view of the plasma source device 5. Note that in Figure 3, the passed shield 54 is shown with a dashed line. Also, Figures 4 and 5 are views cut at the position of the dashed line in Figure 3. Also, Figure 6 is a view cut at the position of the double dashed line in Figure 3.

[0019] The plasma source device 5 includes a gas supply path 51, a dielectric core 52, a helical resonant antenna 53, and a shield 54. The dielectric core 52 and the helical resonant antenna 53 constitute a plasma generation unit that generates plasma by magnetically exciting a processing gas in the gas supply path 51.

[0020] The gas supply passage 51 is composed of pipes 511 to 513, each having an internal flow path 51a (see Figures 5 and 6) through which the processing gas flows. The gas supply passage 51 also has a plasma excitation section 51b (see Figures 5 and 6) in the portion covered by the dielectric core 52. The internal flow path 51a of the plasma excitation section 51b functions as a reactor (reaction chamber) that generates plasma. In the example shown in Figures 5 and 6, the gas supply passage 51 includes pipes 511 to 513, which are connected in series.

[0021] Furthermore, the plasma excitation section 51b of the gas supply passage 51 has gaps (magnetic field transmission spaces) 514 and 515 having a predetermined width. In the example shown in Figures 5 and 6, an annular gap 514 is formed between pipe 511 and pipe 512, communicating from the outer circumference to the inner circumference of the gas supply passage 51. The gap 514 is formed over the entire circumference of the gas supply passage 51. Also, an annular gap 515 is formed between pipe 512 and pipe 513, communicating from the outer circumference to the inner circumference of the gas supply passage 51. The gap 515 is formed over the entire circumference of the gas supply passage 51. Note that in the example shown in Figures 5 and 6, the case in which two gaps 514 and 515 are provided in the plasma excitation section 51b of the gas supply passage 51 is described as an example, but it is not limited to this. It is sufficient to have one or more gaps (514, 515) provided in the plasma excitation section 51b of the gas supply passage 51.

[0022] Here, the pipes 511 to 513 of the gas supply line 51 are made of a non-magnetic metal material such as aluminum. This shields the pipes 511 to 513 so as not to allow the electric field of the helical resonant antenna 53 to pass through the internal flow path 51a. The gas supply line 51 may also be grounded.

[0023] Furthermore, the gaps (magnetic field transmission spaces) 514 and 515 provided in the gas supply passage 51 transmit the magnetic fields of the helical resonant antenna 53 and the dielectric core 52 to the internal flow path 51a. In addition, the magnetic fields (magnetic flux) from the helical resonant antenna 53 and the dielectric core 52 are transmitted from the outer circumference side to the inner circumference side of the internal flow path 51a of the gas supply passage 51, forming a magnetic field in the internal flow path 51a, and the structure also shields the electric field from the helical resonant antenna 53.

[0024] For example, gaps 514 and 515 have a stepped structure. Specifically, gaps 514 and 515 have a structure in which the opening positions on the outer circumference and the opening positions on the inner circumference are located at different positions in the axial direction (direction of flow of the processed gas) of the gas supply passage 51. Also, in the example shown in Figures 5 and 6, gaps 514 and 515 have a crank shape. Gap 514 has a first gap 514a formed radially inward from the opening position on the outer circumference of the gas supply passage 51, a second gap 514b formed radially outward from the opening position on the inner circumference of the gas supply passage 51, and a third gap 514c formed in the axial direction of the gas supply passage 51, connecting the first gap 514a and the second gap 514b. The gap 515 has a first gap 515a formed from the outer circumference opening towards the radially inward side of the gas supply passage 51, a second gap 515b formed from the inner circumference opening towards the radially outward side of the gas supply passage 51, and a third gap 515c formed in the axial direction of the gas supply passage 51, connecting the first gap 515a and the second gap 515b. The outer circumference opening of the gap 514 is located upstream of the gas supply passage 51 compared to the inner circumference opening. The outer circumference opening of the gap 515 is located downstream of the gas supply passage 51 compared to the inner circumference opening. The orientation of the stepped structure is not limited to these, and may be reversed.

[0025] Furthermore, the gas supply passage 51 has a structure that prevents the processing gas flowing through the gas supply passage 51 from leaking out of the gaps 514 and 515. Specifically, dielectric rings 55 and 56 are interposed in the gaps 514 and 515. The dielectric rings 55 and 56 have an annular shape (washer shape) and are made of a dielectric material such as alumina. Dielectric ring 55 is sandwiched between pipes 511 and 512, sealing the gap 514 to prevent processing gas leakage, while allowing the magnetic field (magnetic flux) from the helical resonant antenna 53 and dielectric core 52 to pass through. Dielectric ring 56 is sandwiched between pipes 512 and 513, sealing the gap 515 to prevent processing gas leakage, while allowing the magnetic field (magnetic flux) from the helical resonant antenna 53 and dielectric core 52 to pass through. Although the dielectric ring 55 has been described as being placed in the second gap 514b on the inner circumference side, it is not limited to this and may be placed in any of the gaps 514. Similarly, although the dielectric ring 56 has been described as being placed in the second gap 515b on the inner circumference side, it is not limited to this and may be placed in any of the gaps 515.

[0026] The dielectric core 52 is made of a dielectric material such as alumina or quartz, and is formed in an annular shape with a through hole in the center. A gas supply passage 51 is inserted through the through hole in the dielectric core 52. In other words, the dielectric core 52 is formed in an annular shape so as to surround the gas supply passage 51. Furthermore, the dielectric core 52 is formed in an annular shape so as to surround the plasma excitation section 51b where the gaps 514, 515 of the gas supply passage 51 are formed. The dielectric core 52 is formed in a rectangular annular shape, for example, with wall portions 521, 522, 523, 524. However, the shape of the dielectric core 52 is not limited to this, and it may be formed in a circular annular shape.

[0027] The gas supply passage 51 has two opposing planar sections 51S. The wall section 522 is positioned to contact one of the planar sections 51S of the gas supply passage 51. The wall section 524 is positioned to contact the other planar section 51S of the gas supply passage 51. In other words, a heat transfer section is formed between the gas supply passage 51 and the dielectric core 52. Furthermore, positioning is made easier by bringing the gas supply passage 51 and the dielectric core 52 into contact at the planar sections 51S. Note that the wall section 521 is positioned so as not to contact the gas supply passage 51. The wall section 523 may or may not be in contact with the gas supply passage 51.

[0028] By forming a flat portion 51S in the gas supply passage 51 and bringing it into contact with the wall portions 522 and 524 of the dielectric core 52, the distance between the internal flow path 51a of the gas supply passage 51 and the dielectric core 52 can be reduced, thereby enabling optimal plasma excitation.

[0029] Furthermore, by bringing the gas supply path 51 into contact with the dielectric core 52, the heat transfer between the gas supply path 51 and the dielectric core 52 can be improved. In other words, the heat generated by the helical resonant antenna 53 and the dielectric core 52 when high-frequency power is supplied to the helical resonant antenna 53 can be dissipated to the gas supply path 51.

[0030] The helical resonant antenna 53 is formed by winding it around the wall portion 521 of the dielectric core 52. One end 53a of the helical resonant antenna 53 is connected to the feed wiring 531 and the ground wiring 532. The other end 53b of the helical resonant antenna 53 is open. The feed wiring 531 is connected to the high-frequency power supply 7. The ground wiring 532 is grounded by being connected to the grounded shield 54. The helical resonant antenna 53 is made of a conductive material such as copper. The frequency of the high-frequency power supplied from the high-frequency power supply 7 to the helical resonant antenna 53 is preferably in the UHF band (within the range of 300 MHz to 3 GHz) or the microwave band (within the range of 300 MHz to 300 GHz). The higher the frequency, the higher the excitation density of the induced magnetic field, so the plasma source device 5 can be made smaller.

[0031] The helical resonant antenna 53 may be formed in a spiral shape (toroidal type) by moving the winding position along the wall portion 521 in the lateral direction (direction of the central axis of the wound helical resonant antenna 53), as shown in Figure 4. Alternatively, the helical resonant antenna 53 may be formed so that the coil wires (antenna wires) overlap at the same position on the wall portion 521 (spiral type). Furthermore, the helical resonant antenna 53 may be wound entirely or partially in a toroidal manner, entirely or partially in a spiral manner, or a combination of toroidal and spiral winding. In order to supply a magnetic field to the internal flow path 51a, the winding direction of the helical resonant antenna 53 (the direction in which the wiring of the helical resonant antenna 53 on the side close to the gas supply path 51 extends) is perpendicular to the gaps 154 and 155. Since gaps 154 and 155 and the internal flow path 51a are perpendicular to each other, the winding direction of the helical resonant antenna 53 and the direction of the internal flow path 51a (the axial direction of the internal flow path 51a) are the same. That is, the helical resonant antenna 53 is wound in a direction along the internal flow path 51a.

[0032] Furthermore, by having a structure with a high Q-factor (Quality Factor), the helical resonant antenna 53 can achieve impedance matching with the plasma without the need for a matching circuit. The Q-factor of the helical resonant antenna 53 can be increased by increasing the number of turns and narrowing the pitch.

[0033] The shield 54 is formed to surround the dielectric core 52. The shield 54 shields against electric and magnetic fields from the helical resonant antenna 53 and the dielectric core 52. The shield 54 is made of a non-magnetic metal material such as aluminum. The shield 54 is grounded. The shield 54 may also be electrically connected to the gas supply line 51.

[0034] Figure 7 shows an example of the electromagnetic field distribution of the plasma source device 5. Here, the electromagnetic field strength is indicated by the density of the dots. Figure 7 shows an example of the electromagnetic field distribution in a plane cut at the position of the dashed line in Figure 3.

[0035] The control unit 8 controls the gas supply unit 6 to supply the processing gas to the gas supply path 51, and controls the high-frequency power supply 7 to supply high-frequency power to the helical resonance antenna 53. By supplying high-frequency power from the high-frequency power supply 7 to the helical resonance antenna 53, a circular magnetic flux is formed in the dielectric core 52. The magnetic flux (magnetic field) formed in the dielectric core 52 forms a magnetic field in the internal flow path 51a of the plasma excitation unit 51b through the gaps (magnetic field transmission spaces) 514 and 515 (see FIG. 7).

[0036] This magnetic field generates an axial plasma current of the gas supply path 51 in the internal flow path 51a. This plasma current ignites and excites the plasma of the processing gas in the internal flow path 51a.

[0037] FIG. 8 is an example of a graph showing the relationship between the frequency of the high-frequency power and the reflectivity. The horizontal axis indicates the frequency of the high-frequency power supplied to the helical resonance antenna 53. The vertical axis indicates the reflectivity.

[0038] The length of the helical resonance antenna 53 (the length from one end 53a to which the power supply wiring 531 and the ground wiring 532 are connected to the other end 53b that is open) is set to "odd multiple of λ / 4" where λ is the wavelength of the high-frequency power, so that resonance occurs. In the example shown in FIG. 8, the reflectivity decreases at 725 MHz, and power can be efficiently supplied to the plasma.

[0039] The length of the helical resonance antenna 53 is preferably within the range from "odd multiple of λ / 4 - α" to "odd multiple of λ / 4 + α". α is an allowable value, and for example, it is preferably within the range of "λ / 20 ≤ α ≤ λ / 10".

[0040] Here, the plasma source device according to the reference example will be described. In the plasma source device according to the reference example, a coil is directly wound around the outside of the dielectric pipe through which the processing gas flows, and by supplying high-frequency power to the coil, an inductively coupled plasma (ICP) of the processing gas is generated in the internal flow path of the dielectric pipe.

[0041] In the plasma source device according to the reference example, high-voltage high-frequency power is supplied to the coil not only during plasma ignition but also during plasma lighting. Therefore, when the plasma of the processing gas generated in the internal flow path of the dielectric pipe and the coil electric field are combined, ions are accelerated from the plasma toward the inner wall surface of the dielectric pipe, and the accelerated ions collide with the inner wall surface of the dielectric pipe, damaging the inner wall surface of the dielectric pipe. In particular, when a reducing gas such as NF ３ gas is used as the processing gas, the inner wall surface of the dielectric pipe is consumed by reactive ion etching.

[0042] On the other hand, in the plasma source device 5 shown in FIGS. 2 to 7, by coupling the magnetic field (magnetic flux) of the dielectric core 52 and the plasma from the gaps (magnetic field transmission spaces) 514 and 515, an axial plasma current of the gas supply path 51 is generated in the internal flow path 51a, and the plasma is ignited and excited in the internal flow path 51a of the plasma excitation unit 51b by the magnetic field.

[0043] Further, in the plasma source device 5, the electric field is shielded by the pipes 511 to 513 made of a non-magnetic metal material such as aluminum, and the electric field is shielded by the structure (step structure, crank shape) of the gaps (magnetic field transmission spaces) 514 and 515, so that the coil electric field is shielded from entering the internal flow path 51a. That is, it prevents the plasma of the processing gas generated in the internal flow path 51a of the gas supply path 51 (pipes 511 to 513) from being combined with the coil electric field, suppresses the acceleration of ions from the plasma toward the inner wall surface of the dielectric pipe, suppresses the collision of the accelerated ions with the inner wall surface of the gas supply path 51 (pipes 511 to 513), and suppresses the damage to the inner wall surface of the gas supply path 51 (pipes 511 to 513). That is, the replacement frequency of the gas supply path 51 can be reduced.

[0044] FIG. 9 is an example of a graph showing the relationship between the electron density n ０ and the plasma absorption power P ａｂｓ and FIG. 10 is an example of a graph showing the relationship between the frequency f of the high-frequency power and the plasma skin depth δ ｃ and.

[0045] As shown in FIG. 9, if the radius R of the internal flow path 51a of the gas supply path 51 is considered, the plasma absorption power P ａｂｓ The plasma skin depth δ at which becomes maximum ｃ is approximately 0.57R. That is, when the radius R is within the range of, for example, 2 to 20 mm, the plasma skin depth δ ｃ is within the range of 1 to 11 mm.

[0046] As shown in FIG. 10, when the plasma skin depth δ ｃ is within the range of 1 to 11 mm, the frequency f of the high-frequency power is preferably a high frequency (for example, UHF band, microwave band).

[0047] Here, in the plasma source device according to another reference example, a coil is wound around a ferrite core, and plasma is generated by supplying high-frequency power to the coil. In the plasma source device according to this reference example, when high-frequency power of a high frequency (for example, UHF band, microwave band) is used, magnetic loss may occur in the ferrite core, and the power efficiency may decrease.

[0048] On the other hand, in the plasma source device 5 shown in FIGS. 2 to 7, as shown in FIG. 7, magnetic loss does not occur inside the dielectric core 52. Therefore, even when high-frequency power of a high frequency (for example, UHF band, microwave band) is used, the power efficiency can be improved.

[0049] Further, in the plasma excitation part 51b of the gas supply path 51 covered with the dielectric core 52, it is preferable that the gas supply path 51 is composed of a single gas supply path 51 that does not branch. Thereby, the residence time of the plasma is shortened, and damage to the inner wall surface of the gas supply path 51 (pipes 5××××××) is suppressed.

[0050] As described above, the substrate processing apparatus 1 including the plasma source device 5 has been described. However, the present disclosure is not limited to the above-described embodiments and the like, and various modifications and improvements are possible within the scope of the gist of the present disclosure described in the claims.

[0051] This application claims priority based on Japanese Patent Application No. 2024-189151 filed on October 28, 2024, and the entire contents of these Japanese patent applications are incorporated herein by reference.

[0052] W Substrate 1 Substrate processing device 2 Processing container 3 Mounting platform 4 Exhaust section 5, 5A Plasma source device 6 Gas supply section 7 High-frequency power supply 8 Control section 51 Gas supply path 51a Internal flow path 51b Plasma excitation section 51S Planar section 52 Dielectric core 53 Helical resonant antenna 54 Shield 55, 56 Dielectric ring 511-513 Piping 514, 515 Gap (magnetic field transmission space) 521, 522, 523, 524 Wall section 531 Power supply wiring 532 Grounding wiring

Claims

1. A plasma source device comprising: a gas supply path having an internal channel through which a processing gas is supplied from a gas supply unit; and a plasma generation unit generating plasma by magnetically exciting the processing gas in the gas supply path, wherein the plasma generation unit comprises: a dielectric core surrounding the gas supply path; and a helical resonant antenna wound around the dielectric core along the gas supply path, with one end connected to a power supply wiring that receives high-frequency power from a high-frequency power supply and to an installed grounding wiring, and the other end being open.

2. The plasma source device according to claim 1, wherein the gas supply path has a plasma excitation section in the portion covered by the dielectric core.

3. The plasma source apparatus according to claim 2, wherein the plasma excitation section has a predetermined width and a magnetic field transmission space for transmitting a magnetic field to the internal channel.

4. The plasma source apparatus according to claim 3, wherein the magnetic field transmission space has a structure in which the opening position on the outer circumference side of the gas supply path and the opening position on the inner circumference side of the gas supply path are provided at different positions in the axial direction of the gas supply path.

5. The plasma source apparatus according to claim 3, further comprising a dielectric ring in the magnetic field transmission space.

6. The plasma source device according to claim 1, wherein the length of the helical resonant antenna wound around the dielectric core from one end to the other is within the range of λ / 4 × odd multiple - α to λ / 4 × odd multiple + α, where λ / 20 ≤ α ≤ λ / 10, with respect to the wavelength λ of the high-frequency power.

7. The plasma source device according to claim 1, further comprising a heat transfer section between the gas supply path and the dielectric core.

8. The plasma source device according to claim 1, wherein the dielectric core is formed in an annular shape having a through hole, and the gas supply passage is inserted through the through hole of the dielectric core.

9. The plasma source apparatus according to claim 1, wherein the helical resonant antenna is wound in whole or in part on the dielectric core in a spiral or toroidal manner.

10. A substrate processing apparatus comprising: a processing container; a gas supply unit for supplying a processing gas; a high-frequency power supply for supplying high-frequency power; and a plasma source device for supplying plasma of the processing gas to the processing container, wherein the plasma source device comprises: a gas supply path having an internal flow path through which the processing gas is supplied from the gas supply unit; and a plasma generation unit generating plasma by magnetically exciting the processing gas in the gas supply path, wherein the plasma generation unit comprises: a dielectric core surrounding the gas supply path; and a helical resonant antenna wound around the dielectric core along the gas supply path, with one end connected to a power supply wiring that receives high-frequency power from the high-frequency power supply and an installed grounding wiring, and the other end being open.

11. A control method for a plasma source device comprising: a gas supply path having an internal channel through which a processing gas is supplied from a gas supply unit; a dielectric core surrounding the gas supply path; and a helical resonant antenna wound around the dielectric core along the gas supply path, with one end connected to a power supply wiring that receives high-frequency power from a high-frequency power source and an installed grounding wiring, and the other end open, wherein the control method involves supplying the high-frequency power to the helical resonant antenna and generating plasma by magnetically exciting the processing gas in the gas supply path.

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