Plasma processing apparatus, plasma processing method, and remote plasma source

Abstract

To provide a technique that can generate a high-density remote plasma that can be turned on and off at a high speed to perform plasma processing on a substrate.SOLUTION: A plasma processing apparatus is provided with a chamber, a substrate support part that is provided in the chamber, a remote plasma source that is provided outside the chamber and generates a remote plasma, and a plasma introduction part that introduces the remote plasma generated by the remote plasma source into the chamber. The remote plasma source has a plasma generation container having a ring-shaped space therein, wherein a plasma is generated in the space, a gas supply unit that supplies gas to the plasma generation container, a pair of electrodes opposite to each other and provided in a ring shape along the ring-shaped space of the plasma generation container, a high frequency power source capable of being turned on and off for forming a high frequency electric field between the pair of electrodes, and a coil provided spirally around the plasma generation container and upon supply of high frequency current forming a loop-like magnetic field between the pair of electrodes.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a plasma processing apparatus, a plasma processing method, and a remote plasma source. [Background technology]

[0002] In the manufacturing process of semiconductor devices, plasma processing equipment is used to perform plasma processing on semiconductor wafers, and magnetic plasma processing equipment is known. For example, Patent Document 1 describes a plasma chamber that may be a toroidal loop defined as forming an internal plasma channel with a closed path to maintain plasma current circulation in a closed circuit. Patent Document 2 describes a plasma reactor with an electron beam source without inherent asymmetry, in which capacitively coupled plasma is generated by optimizing the frequencies of multiple power generators and applying them to a space from an upper electrode, while a magnetic field is generated by a coil to enhance plasma density. Patent Document 3 further describes a vertical batch processing system that divides an annular plasma space into multiple zones and discharges and exhausts gases, in which capacitively coupled plasma can be generated in the plasma space, the plasma in the plasma space can be used as remote plasma, and the center of the top plate is made of quartz to allow the magnetic field of the coil to pass through. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2021-530616 [Patent Document 2] Japanese Patent Publication No. 2021-153056 [Patent Document 3] Japanese Patent Application Laid-Open No. 2013-206732 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a technology for generating high-density remote plasma that can be turned on and off quickly to perform plasma processing on a substrate. [Means for solving the problem]

[0005] A plasma processing apparatus according to one embodiment of the present disclosure includes a chamber, a substrate support unit provided within the chamber to support a substrate, a remote plasma source provided outside the chamber to generate remote plasma, and a plasma introduction unit that introduces the remote plasma generated by the remote plasma source into the chamber. The remote plasma source includes a plasma generating vessel having an annular space therein in which plasma is generated, a gas supply unit that supplies gas to the plasma generating vessel, a pair of opposing electrodes provided annularly along the annular space of the plasma generating vessel, a high-frequency power supply that can be turned on and off to form a high-frequency electric field between the pair of electrodes, and a coil that is provided spirally around the plasma generating vessel and to which a high-frequency current is supplied to form a loop-shaped magnetic field between the pair of electrodes. [Effects of the Invention]

[0006] According to the present disclosure, a technology is provided that can generate a high-density remote plasma that can be turned on and off at high speed and perform plasma processing on a substrate. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a cross-sectional view schematically illustrating a plasma processing apparatus according to an embodiment. [Figure 2] 2 is a perspective view showing the appearance of a remote plasma source in the plasma processing apparatus of FIG. 1. FIG. [Figure 3] FIG. 2 is a perspective view for explaining the principle of a remote plasma source in the plasma processing apparatus of FIG. [Figure 4] FIG. 2 is a cross-sectional view for explaining the principle of a remote plasma source in the plasma processing apparatus of FIG. [Figure 5] FIG. 10 is a cross-sectional view showing a modified example of the plasma introduction part. [Figure 6] FIG. 1 is a diagram showing the technique of Patent Document 1 in relation to the remote plasma source of this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments will be described with reference to the accompanying drawings. FIG. 1 is a cross-sectional view showing a schematic diagram of a plasma processing apparatus according to one embodiment, FIG. 2 is a perspective view showing the appearance of a remote plasma source in the plasma processing apparatus of FIG. 1, and FIGS. 3 and 4 are a perspective view and a cross-sectional view for explaining the principle of the remote plasma source in the plasma processing apparatus of FIG. 1.

[0009] The plasma processing apparatus 100 of this embodiment performs plasma processing on a substrate W. The plasma processing is not particularly limited, but a suitable example is a film formation process, particularly PEALD (Plasma Enhanced Atomic Layer Deposition). The substrate W is not particularly limited, but a semiconductor wafer is an example.

[0010] The plasma processing apparatus 100 includes a chamber 10 , a substrate support 20 , a remote plasma source 30 , a plasma introduction unit 40 , and a control unit 50 .

[0011] The chamber 10 is generally cylindrical and made of metal, such as aluminum whose surface has been anodized. An exhaust device 11 is connected to the bottom of the chamber 10 to exhaust the air inside the chamber 10 and adjust the pressure inside the chamber 10 to a desired vacuum atmosphere. A loading / unloading port 12 for loading and unloading the substrate W is formed in the sidewall of the chamber 10, and this loading / unloading port 12 can be opened and closed by a gate valve 13.

[0012] The substrate support part 20 is provided at the bottom of the chamber 10, and the substrate W is supported (placed) on its upper surface. The substrate support part 20 is provided with lifting pins (not shown) that move up and down so as to protrude and sink into the surface of the substrate support part 20 in order to transport the substrate W. The substrate support part 20 may also be provided with a temperature control mechanism such as an electrostatic chuck for electrostatically attracting the substrate W, a heater, or the like.

[0013] The remote plasma source 30 includes a plasma generating chamber 31, a first electrode 32 and a second electrode 33 facing each other, a gas supply unit , a high-frequency power supply 35, and a coil .

[0014] The plasma generating vessel 31 is made of a non-magnetic metal, such as aluminum, and is provided above the chamber 10 in the vicinity of the chamber 10 at a position corresponding to the outer periphery of the substrate W. The plasma generating vessel 31 has an annular space therein, and plasma is generated in this space. When the plasma generating vessel 31 is made of aluminum, its surface may be anodized. A plurality of holes 38 are formed in the bottom of the plasma generating vessel 31.

[0015] The first electrode 32 and the second electrode 33 are arranged annularly along the annular space inside the plasma generating vessel 31, and constitute a pair of electrodes facing each other. In the example of Fig. 1, the first electrode 32 serves as an upper electrode, and the second electrode 33 serves as a lower electrode. An insulating member 37 is provided between the first electrode 32 and the ceiling wall of the plasma generating vessel 31.

[0016] The gas supply unit 34 supplies a plasma gas for generating plasma into the plasma generating vessel 31. The plasma gas is not particularly limited, and for example, any one of Ar gas, H2 gas, N2 gas, and NH3 gas, or a mixture thereof, can be used. A gas other than the plasma gas may be supplied from the gas supply unit 34. Examples of such gases include a pressure adjusting gas, a purge gas, and a processing gas for plasma processing. In this case, the processing gas may or may not be converted into plasma. The plasma gas may also be used as a purge gas. The purge gas and processing gas may be supplied from a gas supply unit separate from the gas supply unit 34.

[0017] High frequency power supply 35 is for forming a high frequency electric field between first electrode 32 and second electrode 33 and can be turned on and off. In Fig. 1, high frequency power is supplied from high frequency power supply 35 to first electrode 32 and second electrode 33 is grounded, but this is not limiting and high frequency power may be supplied to second electrode 33. The frequency of the high frequency power supplied from high frequency power supply 35 may be 450 kHz to 60 MHz.

[0018] As shown in FIG. 2, the coil 36 is wound spirally around the annular plasma generating vessel 31. As shown in FIGS. 3 and 4, a loop-shaped magnetic field B passing through the center of the coil 36 is induced by supplying a high-frequency current I from a high-frequency power supply (not shown). Since the coil 36 is wound around the plasma generating vessel 31, this loop-shaped magnetic field can be formed between and along the first electrode 32 and the second electrode 33 inside the plasma generating vessel 31. By adjusting the arrangement of the coil 36, the position of the loop-shaped magnetic field between the first electrode 32 and the second electrode 33 can be adjusted. The strength of the magnetic field B at this time is not particularly limited and can be set appropriately. For example, it may be 30 G or more.

[0019] Plasma gas is supplied into the plasma generating vessel 31 from a gas supply unit 34. As shown in FIGS. 3 and 4, a loop-shaped magnetic field B is formed between the first electrode 32 and the second electrode 33 by a coil 36, and high-frequency power is supplied from a high-frequency power supply 35. As a result, a high-frequency electric field E is formed between the first electrode 32 and the second electrode 33 in the presence of the loop-shaped magnetic field B, generating capacitively coupled plasma. Then, a plasma current (induced current) flows around the loop-shaped magnetic field B, and electrons in the plasma are concentrated in the plasma space due to E×B drift, generating high-density plasma in the plasma generating vessel 31. The generated plasma is guided downward through a hole 38 in the bottom. The second electrode 33 can be made of punched metal to facilitate the passage of plasma.

[0020] Plasma introduction part 40 Is, The plasma generating vessel 31 has a plasma flow path 41 that is connected to a hole 38 formed in the bottom of the plasma generating vessel 31 and that guides the plasma from the plasma generating vessel 31 toward the chamber 10, and a shower head 42 that guides the plasma from the plasma flow path 41 and discharges the plasma into the processing space S in the chamber 10. The shower head 42 has a diffusion section 43 inside and a plurality of discharge holes 44 formed in the bottom. The plasma generated in the plasma generating vessel 31 contains ions and radicals, but the ions plasma Since the radicals can be suppressed by colliding with the inner walls of the flow path while passing through the flow path 41 and the outlet holes 44 of the shower head 42, mainly radicals are introduced into the processing space S.

[0021] As shown in Figure 5, plasma Instead of the flow path 41, a hole 38' was formed on the side of the plasma generating chamber 31. plasma having a flow path 41' plasma It may also be an introduction portion 40'.

[0022] In the remote plasma source 30, the magnetic field B is constantly formed in the plasma generating vessel 31 by the coil 36, and the plasma in the plasma generating vessel 31 can be turned on and off at high speed by controlling the high frequency power supply 35 on and off in accordance with the gas introduction.

[0023] The control unit 50 controls components of the plasma processing apparatus 100, such as the exhaust unit 11, the gas supply unit 34 of the remote plasma source 30, the high-frequency power supply 35, and a high-frequency power supply (not shown) that supplies high-frequency current to the coil 36. The control unit 50 has a main control unit with a CPU, an input device, an output device, a display device, and a storage device. The processing of the plasma processing apparatus 100 is controlled based on a processing recipe stored in a storage medium of the storage device.

[0024] Next, the operation of the plasma processing apparatus 100 configured as above will be described. First, the substrate W is carried into the chamber 10 and placed on the substrate support part 20. Then, while supplying gas into the chamber 10, the inside of the chamber 10 is evacuated by the exhaust device 11 to adjust the pressure and create a desired vacuum atmosphere.

[0025] Then, plasma is generated by the remote plasma source 30 and introduced into the chamber 10 via the plasma introduction part 40, and plasma processing is performed on the substrate W placed in the chamber 10.

[0026] When generating remote plasma in the remote plasma source 30, a high-frequency current I is supplied to a coil 36 that is wound spirally around the annular plasma generating vessel 31, thereby forming a loop-shaped magnetic field B that passes through the center of the coil 36. This loop-shaped magnetic field B is formed between the first electrode 32 and the second electrode 33.

[0027] In this state, plasma gas is supplied from the gas supply unit 34 into the plasma generating vessel 31, and high-frequency power is supplied from the high-frequency power supply 35 to the first electrode 32 to form a high-frequency electric field E between the first electrode 32 and the second electrode 33. As a result, the plasma gas is excited by the high-frequency electric field E in the plasma generating vessel 31, and capacitively coupled plasma is generated. At this time, an E×B drift occurs due to the loop-shaped magnetic field B formed by the coil 36, and electrons in the plasma concentrate in the plasma space, so that the plasma generated in the plasma generating vessel 31 becomes high density.

[0028] The high-density plasma generated in the plasma generating vessel 31 is guided downward through the hole 38, passes through the plasma flow path 41 and shower head 42 that constitute the plasma introduction section 40, and reaches the processing space S of the chamber 10, where the substrate W is subjected to plasma processing.

[0029] At this time, the ions can be suppressed by colliding with the inner walls of the plasma flow path 41 and the outlet holes 44 of the shower head 42, so that high-density plasma mainly composed of radicals is supplied to the substrate W, and high-efficiency plasma processing is performed on the substrate W with little damage.

[0030] Furthermore, in this embodiment, the plasma in the plasma generating vessel 31 can be turned on and off by turning on and off the high frequency power supply 35 while maintaining the loop-shaped magnetic field formed by the coil 36. Therefore, it is possible to turn on and off the plasma at high speed even though it is a high density plasma that utilizes a magnetic field.

[0031] Patent Document 1 discloses the generation of high-density plasma using a toroidal loop that utilizes magnetism, but in the case of a toroidal loop, plasma is generated using magnetism. FIG. 6 is a diagram showing the technology of Patent Document 1 in conjunction with the remote plasma source of this embodiment. As shown in FIG. 6, by generating a magnetic field H (magnetic field B) that circulates around a pair of annular yokes 91 and 92, an induced current is generated in an annular shape between the yokes 91 and 92, which becomes a plasma current and forms a toroidal loop (toroidal plasma). When plasma is generated using a magnetic field in this way, it is difficult to quickly turn the plasma on and off.

[0032] In contrast to this, in the case of this embodiment, although a high density plasma is produced using a magnetic field, the plasma in the plasma generating vessel 31 can be turned on and off at high speed by turning on and off the high frequency power supply 35 .

[0033] Using this, it is possible to perform two processes: a process of generating plasma in the remote plasma source 30 as described above, introducing the generated plasma into the chamber 10 to perform plasma processing on the substrate W, and a process of supplying a processing gas into the chamber 10 with the plasma turned off to perform processing on the substrate W without using plasma. These processes can be repeated by turning the high-density remote plasma on and off at high speed. An example of a process that uses high-speed on / off of plasma is PEALD.

[0034] PEALD can be performed, for example, using the plasma processing apparatus 100 of this embodiment as follows. That is, with the high-frequency power supply 35 and plasma turned off, a process of introducing a source gas into the processing space S to adsorb it onto the substrate W, and a process of introducing plasma generated by the remote plasma source 30 into the processing space S to react with the source gas adsorbed onto the substrate to form a film are repeated with purging of the chamber in between. When reacting the source gas with plasma, a reactive gas may be introduced as a processing gas from the gas supply unit 34 in addition to the plasma gas.

[0035] To achieve PEALD, the appropriate pressure is 500 mTorr (66.5 Pa) or higher, due to the reactivity and residence time of the source and reactant gases used, and the plasma used is limited to capacitively coupled plasma. In PEALD, it is preferable to use high-density plasma mainly composed of radicals, but to generate radicals more efficiently, not only is it necessary to apply high-frequency power, but technology is also required to maintain the generated capacitively coupled plasma at a high density.

[0036] In this embodiment, when generating remote plasma using capacitively coupled plasma, a ring-shaped magnetic field is formed between a pair of electrodes to concentrate electrons in the plasma space, so that the generated capacitively coupled plasma can be maintained at a high density, making it suitable for PEALD.

[0037] Furthermore, according to this embodiment, the plasma generating vessel 31 of the remote plasma source 30 is positioned close to the chamber 10 in which the substrate W to be processed is placed, so that radicals can be efficiently supplied from the plasma generated in the plasma generating vessel 31 to the processing space S of the chamber 10.

[0038] Although the embodiments have been described above, the disclosed embodiments should be considered to be illustrative and not restrictive in all respects. The above embodiments may be omitted, substituted, or modified in various ways without departing from the scope and spirit of the appended claims.

[0039] For example, in the above embodiment, PEALD was described as an example of plasma processing in which plasma is switched on and off, but this is not limited to this. Furthermore, in the above embodiment, the plasma introduction unit was described as having a plasma flow path and a shower head, but the plasma introduction unit may have a structure that does not use a shower head. Furthermore, in the above embodiment, radicals were mainly supplied to the processing space S, but ions may also be supplied to the processing space S to improve efficiency, such as by promoting etching of the substrate. [Explanation of symbols]

[0040] 10; Chamber 11;Exhaust system 20: Substrate support 30;Remote Plasma Source 31: Plasma generating vessel 32;1st electrode 33;Second electrode 34: Gas supply section 35;High frequency power supply 36; Coil 40: Plasma introduction section 41: Plasma flow channel 42. Shower head 50; control section 100: Plasma treatment device W; substrate S: Processing space

Claims

1. A chamber; a substrate support provided in the chamber and supporting a substrate; a remote plasma source provided outside the chamber for generating a remote plasma; a plasma introduction unit that introduces the remote plasma generated by the remote plasma source into the chamber; Equipped with The remote plasma source comprises: a plasma generating vessel having an annular space therein, in which plasma is generated; a gas supply unit that supplies gas to the plasma generating chamber; a pair of electrodes facing each other and annularly provided along the annular space of the plasma generating vessel; a high-frequency power supply that can be turned on and off to form a high-frequency electric field between the pair of electrodes; a coil that is spirally provided around the plasma generating vessel and that is supplied with a high frequency current to form a loop-shaped magnetic field between the pair of electrodes; A plasma processing apparatus comprising:

2. 2. The plasma processing apparatus according to claim 1, wherein, while supplying plasma gas from the gas supply unit to the plasma generating vessel, the high frequency power supply is turned on to generate plasma between the pair of electrodes while forming the loop-shaped magnetic field between the pair of electrodes by the coil, and the generated plasma is introduced into the chamber to perform plasma processing on the substrate.

3. 3. The plasma processing apparatus according to claim 1, wherein the plasma generating vessel is provided in a position above and in the vicinity of the chamber.

4. 4. The plasma processing apparatus according to claim 3, wherein the plasma introduction unit comprises: a plasma flow path that introduces the plasma from the plasma generating vessel toward the chamber; and a shower head that introduces the plasma from the plasma flow path and discharges the plasma into the chamber.

5. The plasma processing apparatus according to claim 4 , wherein the plasma flow path is connected to a hole formed in a bottom or a side surface of the plasma generating vessel.

6. 6. The plasma processing apparatus according to claim 5, wherein the pair of electrodes includes an upper electrode and a lower electrode, and the lower electrode is made of a punched metal.

7. 3. The plasma processing apparatus according to claim 1, wherein the plasma in the plasma generating chamber is turned on and off at high speed by turning on and off the high frequency power supply at high speed while maintaining the loop-shaped magnetic field formed by the coil.

8. The plasma processing apparatus according to claim 7 , wherein PEALD is performed in the chamber by turning on and off the plasma in the plasma generating vessel at high speed.

9. 3. The plasma processing apparatus according to claim 1, wherein the frequency of the high frequency power source is 450 kHz to 60 MHz, and the strength of the loop magnetic field is 30 G or more.

10. A plasma processing method for performing plasma processing using a plasma processing apparatus including: a chamber; a substrate support unit provided in the chamber for supporting a substrate; a remote plasma source provided outside the chamber for generating remote plasma; and a plasma introduction unit for introducing the remote plasma generated by the remote plasma source into the chamber, the method comprising: The remote plasma source is provided with a plasma generating vessel having an annular space in which plasma is generated, a gas supply unit that supplies gas to the plasma generating vessel, a pair of electrodes that are annularly arranged opposite each other along the annular space of the plasma generating vessel, a high-frequency power supply that can be turned on and off to form a high-frequency electric field between the pair of electrodes, and a coil that is spirally arranged around the plasma generating vessel and to which a high-frequency current is supplied to form a loop-shaped magnetic field between the pair of electrodes; supplying a plasma gas from the gas supply unit to the plasma generating vessel, while forming the loop-shaped magnetic field between the pair of electrodes by the coil, turning on the high frequency power supply to generate plasma between the pair of electrodes, and introducing the generated plasma into the chamber to perform processing on the substrate using the plasma; A plasma processing method comprising:

11. 11. The plasma processing method according to claim 10, further comprising: supplying a processing gas to the chamber while turning off the high frequency power supply to turn off plasma in the plasma generating vessel, and performing a plasma-free process on the substrate.

12. 12. The plasma processing method according to claim 11, wherein the high frequency power supply is turned on and off at high speed while maintaining the loop-shaped magnetic field formed by the coil, thereby turning on and off the plasma in the plasma generating chamber at high speed, and alternately repeating a process without using the plasma and a process using the plasma.

13. In the treatment without using plasma, a source gas is supplied as a processing gas and is adsorbed onto the substrate, and in the treatment with plasma, the source gas adsorbed onto the substrate is reacted to form a film; The plasma processing method according to claim 12 , wherein PEALD is performed by alternately repeating the process without using plasma and the process with using plasma.

14. A remote plasma source that introduces plasma into a chamber in which a substrate is placed, for performing plasma processing on the substrate, a plasma generating vessel having an annular space in which plasma is generated; a gas supply unit that supplies gas to the plasma generating chamber; a pair of electrodes facing each other and annularly provided along the annular space of the plasma generating vessel; a high-frequency power supply that can be turned on and off to form a high-frequency electric field between the pair of electrodes; a coil that is spirally provided around the plasma generating vessel and that is supplied with a high frequency current to form a loop-shaped magnetic field between the pair of electrodes; A remote plasma source having

15. 15. The remote plasma source according to claim 14, wherein the high frequency power supply is turned on to generate plasma between the pair of electrodes while the loop-shaped magnetic field is formed between the pair of electrodes by the coil, while the plasma gas is supplied from the gas supply unit to the plasma generating vessel.

16. 16. The remote plasma source according to claim 14, wherein the plasma generating vessel is provided at a position above and in the vicinity of the chamber.

17. 17. The remote plasma source according to claim 16, wherein the plasma is introduced into the chamber through a hole formed in the bottom or side of the plasma generating vessel.

18. 18. The remote plasma source of claim 17, wherein the pair of electrodes comprises an upper electrode and a lower electrode, the lower electrode being made of a punched metal.

19. 16. The remote plasma source according to claim 14 or 15, wherein the plasma in the plasma generating chamber is turned on and off at high speed by turning on and off the high frequency power supply at high speed while maintaining the loop-shaped magnetic field formed by the coil.

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