JP2023054909A - Plasma processing apparatus and plasma processing method - Google Patents

Abstract

To provide a technique capable of effectively generating an OH radical.SOLUTION: A plasma processing apparatus according to an embodiment of a present disclosure, comprises: a plasma generation mechanism for generating a plasma in a processing container; a flow channel of an ion liquid, provided so as to be contacted to the plasma generated in the processing container; and an OH containing liquid supply part that adds an OH containing liquid to the ion liquid.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to a plasma processing apparatus and a plasma processing method.

A technique of using OH radicals for oxidation treatment is known (see, for example, Patent Document 1).

JP 2006-190877 A

The present disclosure provides a technique capable of efficiently generating OH radicals.

A plasma processing apparatus according to an aspect of the present disclosure includes a plasma generating mechanism for generating plasma within a processing container, an ionic liquid flow path provided in contact with the plasma generated within the processing container, and an OH-containing liquid supply unit for adding an OH-containing liquid to the ionic liquid.

According to the present disclosure, OH radicals can be efficiently generated.

1 is a schematic sectional view showing a plasma processing apparatus of a first embodiment; FIG. A plan view showing an example of a shower plate Cross-sectional view taken along line III-III in FIG. IV-IV line cross-sectional view of FIG. The side view which shows the 1st modification of a shower plate The side view which shows the 2nd modification of a shower plate The top view which shows the 3rd modification of a shower plate VIII-VIII line cross-sectional view of FIG. IX-IX line cross-sectional view of FIG. Schematic cross-sectional view showing a plasma processing apparatus of a first modification of the first embodiment Schematic cross-sectional view showing a plasma processing apparatus of a second modification of the first embodiment Schematic cross-sectional view showing a plasma processing apparatus of a third modification of the first embodiment Schematic diagram showing a plasma processing apparatus of a second embodiment Schematic diagram showing a plasma processing apparatus of a third embodiment

Non-limiting exemplary embodiments of the present disclosure will now be described with reference to the accompanying drawings. In all the attached drawings, the same or corresponding members or parts are denoted by the same or corresponding reference numerals, and overlapping descriptions are omitted.

[First embodiment]
A plasma processing apparatus according to a first embodiment will be described with reference to FIGS. 1 to 9. FIG. The plasma processing apparatus 1 of the first embodiment can be suitably used for a process (plasma processing method) of forming an oxide film by oxidation treatment at a low temperature of 500° C. or less, for example. Examples of oxide films include silicon dioxide (SiO ₂ ). Examples of oxide films include aluminum oxide (Al ₂ O ₃ ), zirconium oxide (ZrO ₂ ), hafnium oxide (HfO ₂ ), strontium titanate (STO; SrTiO ₃ ), and barium titanate (BTO; BaTiO _{3 )} . ) and other high dielectric films (High-k films).

The plasma processing apparatus 1 includes a chamber 10 , a stage 20 , a microwave introduction mechanism 30 , a gas supply section 40 , a shower plate 50 , a liquid circulation section 60 , an OH-containing liquid supply section 70 , an exhaust section 80 and a control section 90 .

The chamber 10 is formed in a substantially cylindrical shape. An opening 12 is formed in a substantially central portion of a bottom wall 11 of the chamber 10 . The bottom wall 11 is provided with an exhaust chamber 13 that communicates with the opening 12 and protrudes downward. A loading/unloading port 15 through which the substrate W passes is formed in the side wall 14 of the chamber 10 . The loading/unloading port 15 is opened and closed by a gate valve 16 . The chamber 10 constitutes a processing container capable of decompressing the inside together with a part of the microwave introducing mechanism 30 . A substrate W is accommodated inside the processing container.

The stage 20 is a mounting table on which the substrate W to be processed is mounted. The stage 20 has a substantially disk shape. The stage 20 is made of ceramics such as aluminum nitride (AlN). The stage 20 is supported by a substantially cylindrical column 21 made of ceramic such as AlN and extending upward from substantially the center of the bottom of the exhaust chamber 13 .

The microwave introduction mechanism 30 constitutes a plasma generation mechanism and is provided above the chamber 10 . A microwave introduction mechanism 30 supplies microwaves into the chamber 10 . The microwave introduction mechanism 30 includes a microwave output section, a microwave transmission section, a microwave radiation section, and the like. Microwaves are output by the microwave output section and introduced into the interior of the chamber 10 through the microwave transmission section and the microwave radiation section. The frequency of microwaves is, for example, 300 MHz to 10 GHz.

The gas supply unit 40 supplies plasma excitation gas to the plasma excitation space A<b>1 located below the ceiling wall 17 of the chamber 10 and above the shower plate 50 . Gas supply 40 may be, for example, a gas nozzle penetrating sidewall 14 of chamber 10 . A plasma excitation gas is supplied from the gas supply unit 40 to the plasma excitation space A1, and the plasma excitation gas is excited by microwaves to generate plasma P. As shown in FIG. Rare gases such as argon (Ar), krypton (Kr), and xenon (Xe) are examples of plasma excitation gases.

The shower plate 50 partitions the inside of the chamber 10 into a plasma excitation space A1 in which plasma P is generated and a process space A2 in which the stage 20 is provided. Shower plate 50 is made of a metal material such as stainless steel or aluminum. The shower plate 50 is a flat plate having a circular planar shape (FIG. 2). The shower plate 50 has an outer frame 51, plasma passages 52 and grooves 53 (FIG. 2).

The outer frame 51 has an annular shape with an outer diameter approximately equal to the inner diameter of the chamber 10 . The outer frame 51 is attached to the inner wall of the chamber 10 .

The plasma passage portion 52 is positioned inside the outer frame 51 . The plasma passage portion 52 has a plurality of stripes 52a that intersect at approximately 90 degrees to form a lattice. The plurality of streaks 52a are provided at intervals of 10 cm or less, for example. Plasma P generated in plasma excitation space A1 passes through openings 52b defined by a plurality of streaks 52a and is supplied to process space A2.

The grooves 53 are formed on the shower plate 50, that is, on the outer frame 51 and the stripes 52a. The grooves 53 form channels (hereinafter also referred to as “liquid channels”) through which the ionic liquid IL flows on the shower plate 50 . The groove 53 includes a liquid receiving portion 53a, a liquid discharging portion 53b, and a flow path forming portion 53c.

The liquid receiver 53 a is provided on the outer frame 51 . However, the liquid receiver 53a may be provided on the streak 52a. An ionic liquid IL containing an OH-containing liquid is dropped onto the liquid receiver 53a.

The liquid discharge portion 53b is provided, for example, on the outer frame 51 on the side opposite to the liquid receiving portion 53a with the center O of the shower plate 50 interposed therebetween. However, the liquid discharge portion 53b may be provided on the streak 52a. The liquid discharge part 53b discharges the ionic liquid IL from above the shower plate 50 . The ionic liquid IL discharged from the liquid discharge portion 53b flows to the bottom wall 11 along the inner surface of the side wall 14, for example.

The flow path forming portion 53c is formed on the outer frame 51 and the stripes 52a. One end of the flow path forming portion 53c communicates with the liquid receiving portion 53a, and the other end communicates with the liquid discharging portion 53b. The flow path forming portion 53c transports the ionic liquid IL dripped onto the liquid receiving portion 53a toward the liquid discharging portion 53b. The ionic liquid IL flowing through the flow path forming portion 53c contacts the plasma P generated in the plasma excitation space A1. Thereby, the ionic liquid IL is heated by the plasma P, and the OH-containing liquid contained in the ionic liquid IL evaporates. Furthermore, the evaporated OH-containing liquid is excited by the plasma P to generate OH radicals. The generated OH radicals are supplied to the process space A2 through the openings 52b of the shower plate 50. As shown in FIG. Thereby, the substrate W is oxidized. As shown in FIG. 2, the flow path forming portion 53c is preferably formed to zigzag from the liquid receiving portion 53a toward the liquid discharging portion 53b. This increases the amount of the ionic liquid IL in contact with the plasma P on the shower plate 50, thereby increasing the amount of OH radicals generated.

The height position of the upstream portion U of the flow path forming portion 53c is preferably higher than the height position of the downstream portion D thereof. As a result, the ionic liquid IL flows from the upstream portion U toward the downstream portion D under its own weight. The upstream portion U is in the vicinity of the position communicating with the liquid receiving portion 53a. The downstream portion D is in the vicinity of the position communicating with the liquid discharge portion 53b. For example, as shown in FIG. 5, by inclining the shower plate 50 with respect to the horizontal plane H so that the upstream portion U is higher than the downstream portion D, the height position of the upstream portion U is changed to the height of the downstream portion D. It can be higher than the horizontal position. Further, as shown in FIG. 6, for example, by forming the shower plate 50 so that the thickness of the shower plate 50 in the upstream portion U is thicker than the thickness of the shower plate 50 in the downstream portion D, the thickness of the shower plate 50 in the upstream portion U The height position can be higher than the height position of the downstream portion D.

As shown in FIG. 7, the flow path forming portion 53c may have an exposed portion V1 exposed to the plasma excitation space A1 and a non-exposed portion V2 not exposed to the plasma excitation space A1. The exposed portion V1 is a region in which the upper opening of the groove 53 is not closed by the lid 54 . The non-exposed portion V2 is formed by covering the upper opening of the groove 53 with the lid 54. As shown in FIG. Since evaporation of H ₂ O is suppressed in the non-exposed portion V2, the amount of the OH-containing liquid contained in the ionic liquid IL in the downstream portion D can be ensured. As a result, the density difference between the OH radicals generated in the upstream portion U and the OH radicals generated in the downstream portion D can be reduced. Although the number and size of the lids 54 are not limited, it is preferable to arrange more lids 54 in the upstream portion U than in the downstream portion D, for example. As a result, the evaporation amount of the OH-containing liquid in the upstream portion U is selectively suppressed, so that the amount of the OH-containing liquid contained in the ionic liquid IL in the downstream portion D can be ensured. Further, it is preferable that the lid 54 arranged in the upstream portion U is longer than the lid 54 arranged in the downstream portion D in the direction along the liquid flow path. As a result, the evaporation amount of the OH-containing liquid in the upstream portion U can be suppressed more than the evaporation amount of the OH-containing liquid in the downstream portion D, so that the amount of the OH-containing liquid contained in the ionic liquid IL in the downstream portion D can be secured. Further, as shown in FIG. 8, side grooves 55 may be provided on both sides of the groove 53 to allow the ionic liquid IL overflowing from the groove 53 to flow. The depth of the side groove 55 may be shallower than the depth of the groove 53, for example. The side groove 55 may be provided only on one side of the groove 53 . Moreover, as shown in FIG. 9, it is preferable to flow the ionic liquid IL so as to cover the upper surface of the lid 54 . Since this prevents the lid 54 from being exposed to the plasma P, plasma damage to the lid 54 is suppressed.

The liquid circulation unit 60 recovers the ionic liquid IL from the chamber 10 and supplies the recovered ionic liquid IL to the grooves 53 on the shower plate 50 . The liquid circulation section 60 includes a storage tank 61 , a recovery port 62 , a temperature controller 63 , a viscosity pump 64 , a supply pipe 65 and a flow rate controller 66 .

The storage tank 61 stores the ionic liquid IL. Examples of the ionic liquid IL include 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-n-octylpyridinium bis(trifluoromethanesulfonyl)imide, 1-n-butyl-1-methylpiperidinium Bis(trifluoromethanesulfonyl)imide, 1,1,1-tri-n-butyl-1-n-dodecylphosphonium bis(trifluoromethanesulfonyl)imide, tributylhexadecylphosphonium 3-trimethylsilyl-1-propanesulfonate (BHDP・DSS), N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium tetrafluoroborate (DEME BF4), N-(2-methoxyethyl)-N-methylpyrrolidinium bis(trifluoro romethanesulfonyl)imide (MEMP-TFSI), 1-ethyl-3-methylimidazolium acetate (EMI-AcO), choline chloride urea. Note that the ionic liquid IL is not limited to this, and another ionic liquid IL may be used as long as it has the property of absorbing the OH-containing liquid. When H ₂ O is used as the OH-containing liquid, DEME·BF4 is suitable as the ionic liquid IL from the viewpoint of easily absorbing H ₂ O.

The recovery port 62 includes a discharge groove 62a and a discharge hole 62b. The discharge groove 62 a is formed in an annular shape on the bottom wall 11 . The discharge groove 62a guides the ionic liquid IL reaching the bottom wall 11 to the discharge hole 62b. The discharge hole 62b is formed in the bottom surface of the discharge groove 62a and penetrates the bottom wall 11. As shown in FIG. The ionic liquid IL that has reached the discharge groove 62a flows into the storage tank 61 through the discharge hole 62b.

The temperature controller 63 includes a heater, a temperature sensor (none of which are shown), and the like. The temperature controller 63 adjusts the temperature of the ionic liquid IL in the storage tank 61 by controlling the heater based on the detected value of the temperature sensor.

A viscous pump 64 is connected to the reservoir tank 61 . The viscous pump 64 is positioned vertically below the storage tank 61, for example. The viscous pump 64 feeds the ionic liquid IL from inside the storage tank 61 to the supply pipe 65 .

The supply pipe 65 has one end connected to the viscous pump 64 and the other end passing through the side wall 14 and positioned in the plasma excitation space A1. The supply pipe 65 drips the ionic liquid IL into the groove 53 from above the shower plate 50 . The ionic liquid IL dripped into the groove 53 flows from the liquid receiving portion 53 a through the flow path forming portion 53 c to the liquid discharging portion 53 b and then along the inner surface of the side wall 14 to the bottom wall 11 .

A flow controller 66 is interposed in the supply pipe 65 . A flow controller 66 controls the flow rate of the ionic liquid IL flowing through the supply pipe 65 . Flow controller 66 is, for example, a liquid mass flow controller.

The OH-containing liquid supply unit 70 adds the OH-containing liquid to the ionic liquid IL. The OH-containing liquid supply section 70 includes a supply source 71 , a supply pipe 72 and a flow controller 73 .

Source 71 is a source of OH-containing liquid. OH-containing liquids include, for example, water (H ₂ O), heavy water (D ₂ O), and alcohols.

One end of the supply pipe 72 is connected to the supply source 71 . The other end of the supply pipe 72 is connected to the supply pipe 65 outside the chamber 10 and adds the OH-containing liquid to the ionic liquid IL flowing through the supply pipe 65 outside the chamber 10 . However, the other end of the supply pipe 72 may be connected to the supply pipe 65 inside the chamber 10 and the OH-containing liquid may be added to the ionic liquid IL flowing through the supply pipe 65 inside the chamber 10 . Moreover, the supply pipe 72 passes through the side wall 14 and is positioned above the shower plate 50 without being connected to the supply pipe 65 at the other end, and drips the OH-containing liquid into the groove 53 from above the shower plate 50 . It may be configured as In this case, the OH-containing liquid is dropped onto the grooves 53 separately from the ionic liquid IL, and the OH-containing liquid is added to the ionic liquid IL within the grooves 53 . Thus, the supply pipe 72 supplies the OH-containing liquid to the ionic liquid IL on the downstream side of the viscous pump 64 .

A flow rate controller 73 controls the flow rate of the OH-containing liquid flowing through the supply pipe 72 . The flow rate controller 73 adjusts the flow rate of the OH-containing liquid to, for example, 0.1% to 3.0% of the flow rate of the ionic liquid IL. Flow controller 73 is, for example, a liquid mass flow controller.

The exhaust section 80 includes an exhaust pipe 81 and an exhaust device 82 . The exhaust pipe 81 is provided on the bottom wall of the exhaust chamber 13 . The exhaust device 82 is connected to the exhaust pipe 81 . The evacuation device 82 includes a vacuum pump, a pressure control valve, etc., and evacuates the inside of the chamber 10 through the evacuation pipe 81 to reduce the pressure.

The control unit 90 has a memory, a processor, an input/output interface, and the like. The memory stores programs executed by the processor and recipes including conditions for each process. The processor executes a program read from the memory and controls each part of the plasma processing apparatus 1 through the input/output interface based on the recipe stored in the memory.

As described above, the plasma processing apparatus 1 includes the shower plate 50 including the liquid flow path provided so as to be in contact with the plasma P generated in the chamber 10, and the OH-containing liquid for adding the OH-containing liquid to the ionic liquid IL. and a liquid supply unit 70 . As a result, the ionic liquid IL added with the OH-containing liquid can flow through the liquid flow path formed on the shower plate 50 . Since the ionic liquid IL flowing through the liquid channel is in contact with the plasma P, the ionic liquid IL is heated by the plasma P, the OH-containing liquid contained in the ionic liquid IL evaporates, and OH radicals are generated. Since the OH-containing liquid is supplied to the vicinity of the source of plasma P in this manner, OH radicals can be efficiently generated. In addition, since OH radicals are generated by the ionic liquid IL flowing through the liquid channels formed on the shower plate 50, water vapor (H ₂ O) is separately supplied into the chamber 10 in order to generate OH radicals. You don't have to. Therefore, a water vapor supply nozzle for supplying water vapor into the chamber 10 becomes unnecessary.

In addition, according to the plasma processing apparatus 1 , the liquid channel is prevented from being exposed to the plasma P by causing the ionic liquid IL to flow through the liquid channel formed on the shower plate 50 . As a result, plasma damage to the shower plate 50 is reduced, and contamination such as metal contamination in the chamber 10 can be suppressed.

Further, according to the plasma processing apparatus 1, by adjusting the temperature of the ionic liquid IL flowing through the liquid channel, the ionic liquid IL can function as a temperature control fluid. For example, when plasma processing is performed in the chamber 10, the shower plate 50 is exposed to the plasma P and becomes hot. Therefore, by flowing the low-temperature ionic liquid IL through the liquid flow channel, the shower plate 50 can be cooled and the temperature of the shower plate 50 can be suppressed.

Next, referring to FIG. 10, a plasma processing apparatus according to a first modified example of the first embodiment will be described. As shown in FIG. 10, in the plasma processing apparatus 1A of the first modified example, guide grooves 14a are formed in the inner surface of the side wall 14 to allow the ionic liquid to flow along the circumferential direction of the chamber 10. As shown in FIG. The guide groove 14a has a spiral shape extending along the circumferential direction of the inner surface of the side wall 14, for example. Thereby, the path from the liquid discharge portion 53b to the recovery port 62 can be determined. Other configurations are the same as those of the plasma processing apparatus 1 . Effects similar to those of the plasma processing apparatus 1 can also be obtained by the plasma processing apparatus 1A of the first modified example.

Next, with reference to FIG. 11, a plasma processing apparatus according to a second modification of the first embodiment will be described. As shown in FIG. 11, the plasma processing apparatus 1B of the second modification has a second gas supply section 42. As shown in FIG. The second gas supply unit 42 supplies process gas to the process space A2. The second gas supply 42 may be, for example, a gas nozzle penetrating the side wall 14 of the chamber 10 . Examples of process gases include silicon-containing gases and metal-containing gases. Other configurations are the same as those of the plasma processing apparatus 1 . Effects similar to those of the plasma processing apparatus 1 can also be obtained by the plasma processing apparatus 1B of the second modification.

Next, with reference to FIG. 12, a plasma processing apparatus according to a third modification of the first embodiment will be described. As shown in FIG. 12, the plasma processing apparatus 1C of the third modified example has a third gas supply section 43. As shown in FIG. The third gas supply section 43 has a supply source 43a, a flow path 43b, and ejection holes 43c. The supply source 43a is a process gas supply source. Examples of process gases include silicon-containing gases and metal-containing gases. Flow path 43 b is formed in shower plate 50 . The ejection hole 43c opens below the shower plate 50 from the flow path 43b. The third gas supply unit 43 supplies the process gas from the supply source 43a to the process space A2 through the flow path 43b and the ejection holes 43c. Other configurations are the same as those of the plasma processing apparatus 1 . Effects similar to those of the plasma processing apparatus 1 can also be obtained by the plasma processing apparatus 1C of the third modification.

Also, two or more of the first to third modifications may be combined. That is, the plasma processing apparatus may have two or more of the guide groove 14a, the second gas supply section 42, and the third gas supply section 43. FIG.

[Second embodiment]
An example of the plasma processing apparatus according to the second embodiment will be described with reference to FIG. As shown in FIG. 13, the plasma processing apparatus 2 of the second embodiment does not have the shower plate 50, but has the liquid supply member 100 fixed to the side walls 14 and the ceiling wall 17. As shown in FIG. Other configurations are the same as those of the plasma processing apparatus 1 .

The liquid supply member 100 is provided along the circumferential direction of the chamber 10 . A first channel 101 and a second channel 102 are formed in the liquid supply member 100 . The first channel 101 is formed along the circumferential direction of the chamber 10 inside the liquid supply member 100 . The first channel 101 has an annular shape. The ionic liquid IL is supplied to the first channel 101 from the supply pipe 65 . One end of the second channel 102 communicates with the first channel 101 and the other end communicates with the inside of the chamber 10 . The other end of the second flow path 102 is provided so as to contact the plasma P generated within the chamber 10 . It is preferable that a plurality of second flow paths 102 be provided at intervals in the circumferential direction of the chamber 10 . As a result, the ionic liquid IL can be supplied to a wide range of the side wall 14, so the amount of the ionic liquid IL in contact with the plasma P increases. As a result, the amount of evaporation of the OH-containing liquid increases and the amount of OH radicals generated increases.

The ionic liquid IL supplied to the first channel 101 is supplied into the chamber 10 via the second channel 102 and flows along the inner surface of the side wall 14 to the bottom wall 11 . At this time, the ionic liquid IL contacts the plasma P generated within the chamber 10 . Thereby, the ionic liquid IL is heated by the plasma P, and the OH-containing liquid contained in the ionic liquid IL evaporates. Furthermore, the evaporated OH-containing liquid is excited by the plasma P to generate OH radicals. Further, grooves (not shown) for flowing the ionic liquid along the circumferential direction of the chamber 10 may be formed on the inner surface of the side wall 14 . In addition, a transmission window (not shown) formed of quartz or the like is provided in a part of the side wall 14, and the ionic liquid IL containing the OH-containing liquid flowing on the inner surface of the side wall 14 through the transmission window is irradiated with ultraviolet light. A source (not shown) may be provided. By irradiating the ionic liquid IL containing the OH-containing liquid with ultraviolet light from the irradiation source, the amount of OH radicals generated increases.

Effects similar to those of the plasma processing apparatus 1 can also be obtained by the plasma processing apparatus 2 of the second embodiment.

[Third embodiment]
An example of the plasma processing apparatus according to the third embodiment will be described with reference to FIG. As shown in FIG. 14, the plasma processing apparatus 3 of the third embodiment does not have a microwave introduction mechanism 30, but has an inductively coupled plasma generation mechanism 31. As shown in FIG. Other configurations are the same as those of the plasma processing apparatus 2 .

The inductively coupled plasma generation mechanism 31 constitutes a plasma generation mechanism and is provided above the chamber 10 . The inductively coupled plasma generation mechanism 31 has a high frequency power source, a coil, and the like. A high-frequency current is supplied from the high-frequency power source to the coil, thereby exciting the plasma excitation gas supplied into the chamber 10 and generating plasma P. As shown in FIG.

Effects similar to those of the plasma processing apparatus 1 can also be obtained by the plasma processing apparatus 3 of the third embodiment. The plasma processing apparatus may have a capacitively coupled plasma generating mechanism instead of the inductively coupled plasma generating mechanism 31 .

In the above embodiments, the shower plate 50 is an example of a partition member, the plasma excitation space A1 is an example of a first space, and the process space A2 is an example of a second space.

It should be considered that the embodiments disclosed this time are illustrative in all respects and not restrictive. The above-described embodiments may be omitted, substituted or modified in various ways without departing from the scope and spirit of the appended claims.

1, 1A to 1C, 2, 3 plasma processing apparatus 10 chamber 30 microwave introduction mechanism 31 inductively coupled plasma generation mechanism 53 groove 70 OH-containing liquid supply unit

Claims (7)

a plasma generating mechanism for generating plasma within the processing vessel;
an ionic liquid flow path provided in contact with the plasma generated in the processing container;
an OH-containing liquid supply unit that adds an OH-containing liquid to the ionic liquid;
A plasma processing apparatus comprising: a mounting table provided in the processing container;
a partition member that partitions the inside of the processing container into a first space in which the plasma is generated and a second space in which the mounting table is provided;
with
wherein the channel is formed in the partition member,
The plasma processing apparatus according to claim 1. The flow path is
an exposed portion exposed to the first space;
and a non-exposed portion that is not exposed to the first space,
The plasma processing apparatus according to claim 2. The height position of the upstream portion of the flow channel is higher than the height position of the downstream portion,
4. The plasma processing apparatus according to claim 2 or 3. The OH-containing liquid supply unit drips the OH-containing liquid into the channel from a position higher than the height position of the upstream part.
The plasma processing apparatus according to claim 4. the OH-containing liquid is _H2O ;
The plasma processing apparatus according to any one of claims 1 to 5. housing the substrate in a processing vessel;
supplying an ionic liquid into the processing vessel;
adding an OH-containing liquid to the ionic liquid;
exposing the ionic liquid to which the OH-containing liquid is added to plasma to generate OH radicals;
performing an oxidation treatment on the substrate with the generated OH radicals;
A plasma processing method comprising:

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