Plasma generating device and plasma processing method

Abstract

To provide a plasma generator capable of efficiency generating a long plasma even in the case of using high frequency power of 1 MHz or less, or in a depression state, and provide a plasma processing method.SOLUTION: A plasma generator comprises: a chamber; and a gas flow pipe of which an open end on both sides is communicated with the chamber. The gas flow pipe has an open end at an end part of a first straight line part, a second straight line part connected to both sides of the first straight line part via a bent part at predetermined connection angles θ1 and θ2 at an inner side direction, and a third straight line, and includes a pair of air core coils which is oppositely arranged on both side surfaces of the gas flow pipe and a high frequency power supply that generates a dielectric heat plasm in a state where a plasma generation gas is flowed in the gas flow pipe by supplying the high frequency power to the air core coils, in which both of the connection angles θ1 and θ2 are 45±10 degrees.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a plasma generating apparatus, and more particularly to a high-frequency induction thermal plasma generating apparatus and a plasma processing method using the same. [Background technology]

[0002] High-frequency induction thermal plasma can form a high-temperature, highly reactive thermal plasma space without electrodes, which prevents the introduction of impurities caused by melting of electrode metals, and is therefore widely used as a variety of surface treatment methods and film formation methods.

[0003] Conventional high-frequency induction thermal plasma devices have a configuration in which an induction coil is wound around the outer periphery of a cylindrical plasma torch. Plasma is ignited by applying a high voltage to the inside of the plasma torch to generate a discharge while flowing an inert gas such as argon gas inside the plasma torch and supplying high-frequency power to the induction coil. After that, various chemical reactions can be carried out by supplying raw materials into the plasma torch.

[0004] In an apparatus using such a cylindrical plasma torch, it has been difficult to expand the area to be processed by plasma in response to the recent increase in size of semiconductor wafers and liquid crystal displays. That is, when the diameter of the cylindrical plasma torch is increased, it becomes necessary to increase the high frequency power supplied to the induction coil and improve the cooling efficiency, which places a limit on the expansion of the treatment area.

[0005] Therefore, with the aim of expanding the area of ​​plasma processing, for example, Patent Document 1 discloses a technology in which plasma is injected into a vacuum chamber from a gas flow pipe having a shape in which a pair of open ends are formed by cutting out a portion of an annular loop tube surrounding a central axis. Although this technology is effective in achieving a certain degree of area widening, when attempting to increase the length of the plasma irradiated onto the substrate in order to process a large substrate, it is necessary to increase the size of the circular loop. As a result, the plasma that does not directly act on the substrate, i.e., does not contribute to the processing of the substrate, becomes very long, which may result in a large waste of the components that make up the device and the high-frequency power used to generate the plasma, and there is room for further improvement.

[0006] Furthermore, Non-Patent Document 1 and Patent Document 2 disclose technology using a racetrack-shaped chamber, but while this device (both report and illustrate operation at 13.56 MHz and atmospheric pressure) eliminates waste of components and high-frequency power, it has the problem of being unable to generate plasma using high-frequency power of 1 MHz or less, which is relatively easy to handle, and in particular unable to generate plasma under reduced pressure rather than atmospheric pressure. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-215942 [Patent Document 2] International Publication No. 2014 / 045547 [Non-patent literature]

[0008] [Non-Patent Document 1] Tomohiro Okumura et al., Annealing performance improvement of elongated inductively coupled plasma torch and its application to recovery of plasma-induced Si substrate damage, Japanese Journal of Applied Physics, Vol.53, No.3S2(2014) Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention has been made to solve these conventional problems, and aims to provide a plasma generating apparatus and a plasma processing method that can efficiently generate long plasma even when using high frequency power of 1 MHz or less or even under reduced pressure. [Means for solving the problem]

[0010] A plasma generation apparatus according to the present invention comprises a chamber and a gas flow pipe having both open ends connected to the chamber, the gas flow pipe having a first straight section and second and third straight sections connected to either side of the first straight section via bends at predetermined inward connection angles θ1 and θ2, the open ends being at the ends of the first and third straight sections, a pair of air-core coils arranged opposite each other on both sides of the gas flow pipe, and a high-frequency power supply that supplies high-frequency power to the air-core coils to generate induction thermal plasma while a plasma generating gas is flowing through the gas flow pipe, and the connection angles θ1 and θ2 are 45±10 degrees.

[0011] Here, the distance between the open ends of the second and third straight portions on both sides that communicate with the chamber can be adjusted by adjusting the length of the first straight portion, and can be made longer than in conventional loop structures. Therefore, the lengths of the second and third straight portions are shorter than the length of the first straight portion. Alternatively, an inlet for the plasma generating gas may be provided in the first straight section, and an inlet for introducing the source material directly into the chamber. In this case, the source material is not contained in the gas flow pipe, so the induction thermal plasma state is stable.

[0012] In the present invention, it is preferable to have a pressure reducing means for reducing the pressure inside the chamber.

[0013] In the present invention, the high frequency power supply preferably has an output frequency of 1 MHz or less.

[0014] When the above-described plasma generating device is used, the plasma region in the chamber is wide, and the plasma processing method can be applied to a long base material (substrate). Therefore, the plasma processing method according to the present invention includes a chamber and a gas flow pipe having both open ends connected to the chamber, the gas flow pipe having a first straight section and second and third straight sections connected to either side of the first straight section via bends at predetermined inward connection angles θ1 and θ2, the gas flow pipe having the open ends at the ends of the first straight section and third straight sections, the second and third straight sections being connected to either side of the first straight section via bends at predetermined inward connection angles θ1 and θ2, the gas flow pipe having a pair of air-core coils arranged opposite each other on both sides of the gas flow pipe, and a high-frequency power supply that supplies high-frequency power to the air-core coils to generate induction thermal plasma while a plasma generating gas is flowing through the gas flow pipe, the connection angles θ1 and θ2 being 45±10 degrees. Here, the plasma processing method according to the present invention preferably includes a pressure reducing means for reducing the pressure inside the chamber, and the high frequency power source preferably has an output frequency of 1 MHz or less. [Effects of the Invention]

[0015] The plasma generation apparatus according to the present invention comprises a chamber and a gas flow pipe whose open ends communicate with the chamber, the gas flow pipe having a first straight section and second and third straight sections which are connected to both sides of the first straight section via bends at predetermined inward connection angles θ1 and θ2, the open ends being at the ends of the first and third straight sections, a pair of air-core coils arranged opposite each other on both sides of the gas flow pipe, and a high-frequency power supply which supplies high-frequency power to the air-core coils to generate induction thermal plasma while a plasma generating gas is flowing through the gas flow pipe, the connection angles θ1 and θ2 being 45±10 degrees, so that the thermal plasmas injected from the open ends on both sides overlap on the surface of a substrate held in the chamber, and a uniform plasma region is formed on the surface of the substrate. The reason for setting the connection angles θ1 and θ2 will be explained in detail in the embodiment. [Brief explanation of the drawings]

[0016] [Figure 1] 1 shows a schematic diagram of the overall configuration of a plasma generation device according to a first embodiment of the present invention. [Figure 2] 1 shows a cross-sectional view of a gas distribution pipe and a chamber when induction thermal plasma is generated inside the gas distribution pipe and a substrate is placed directly below the gas distribution pipe. [Figure 3] 1 shows a side view of an air-core coil used in the plasma generation device of the first embodiment. [Figure 4] 10A and 10B are diagrams illustrating the influence of the connection angle between the second straight portion and the third straight portion. [Figure 5] 1 shows an example of the configuration of a plasma generation device according to a second embodiment. [Figure 6] Ar / N2ICTP emission pattern. [Figure 7] The x-direction distribution of the N atom spectrum is shown. DETAILED DESCRIPTION OF THE INVENTION

[0017] A first embodiment of the present invention will now be described with reference to the accompanying drawings. FIG. 1 shows a schematic diagram of the plasma device, FIG. 2 shows a cross-sectional view of the gas flow pipe and the chamber, and FIG. 3 shows a side view of the air-core coil. The plasma generation device according to the present invention includes a chamber 1 and a gas flow pipe 2 whose open ends (2a, 2b) on both sides communicate with the chamber 1. The gas flow pipe 2 has a first straight section 2C, a second straight section 2D connected to both sides of the first straight section via bends (first bend 2F, second bend 2G) at predetermined connection angles θ1 and θ2 in the inward direction, and open ends (2a, 2b) at the end of the third straight section 2E. The gas generation device also includes a pair of air-core coils 3 arranged opposite each other on both sides of the gas flow pipe 2, and a high-frequency power source 6 that supplies high-frequency power to the air-core coils 3 to generate induction thermal plasma while a plasma-generating gas is flowing through the gas flow pipe 2, and the connection angles θ1 and θ2 are 45±10 degrees. The configuration of the plasma generating device will be specifically described below.

[0018] The plasma generating device has a chamber 1 to which a gas flow pipe 2 is connected. The gas flow pipe 2 is connected to the chamber 1 at a pair of open ends (2a, 2b). Furthermore, an air-core coil 3 having a pair of winding portions is disposed on both sides near the gas flow pipe 2 . Furthermore, a plasma generating gas inlet 4 is formed in the middle of the gas flow pipe 2 , and a source material inlet 5 is formed in the chamber 1 .

[0019] The air-core coil 3 has a pair of winding portions 31 and 32, which are arranged facing each other so as to sandwich the gas flow pipe 2 from both side surfaces. The pair of winding portions 31 and 32 are wound along both sides of the gas flow pipe 2, and each have a first end 31a and 32a close to the gas flow pipe 2 and a second end 31b and 32b away from the gas flow pipe 2 along the central axis C. A high-frequency power supply 6 is connected between the first ends 31a and 32a of both winding portions 31 and 32, and the second ends 31b and 32b of both winding portions 31 and 32 are short-circuited to each other via a short-circuit portion 33.

[0020] Furthermore, a plasma generating gas supply unit 7 is connected to the plasma generating gas inlet 4 , and a raw material supply unit 8 is connected to the raw material inlet 5 . In this embodiment, the plasma generating gas inlet 4 is disposed in the middle of the gas flow pipe 2, which is the farthest from the chamber 1, and the raw material inlet 5 is disposed in the center of the pair of open ends (2 a, 2 b) of the gas flow pipe 2 connected to the chamber 1.

[0021] As shown in FIG. 2, the gas flow pipe 2 has a first straight portion 2C with a length L1 parallel to the longitudinal direction of the substrate S placed in the chamber 1, and second straight portion 2D and third straight portion 2E on either side of the first straight portion 2C, each with a length L2 shorter than that of the first straight portion 2C. The gas flow pipe 2 is made up of a first bent portion 2F that connects the first straight portion 2C and the second straight portion 2D at a predetermined inward connecting angle θ1, and a second bent portion 2G that connects the first straight portion 2C and the third straight portion 2E at a predetermined inward connecting angle θ2, and has a pair of open ends, consisting of an open end 2a provided on the second straight portion 2D and an open end 2b provided on the third straight portion 2E. Therefore, the connection angles θ1 and θ2 correspond to the outer connection angles of the second straight portion 2D and the third straight portion 2E with respect to the chamber 1. The inside of gas flow pipe 2 communicates with the inside of chamber 1 via these open ends 2a and 2b. Furthermore, the source material inlet 5 communicates with the inside of the chamber 1 between the pair of open ends 2a and 2b.

[0022] In this embodiment, the connection angles θ1 and θ2 are both in the range of 45°±10°.

[0023] Furthermore, within the chamber 1, a substrate holder 9 is disposed for holding a base material (substrate) S to be subjected to plasma treatment. The substrate holding part 9 holds the substrate S so that the surface of the substrate S is positioned between the pair of opening ends 2a and 2b of the gas flow pipe 2 and the point P where the center lines T1 and T2 extending along the central axes of the second straight section 2D and the third straight section 2E intersect.

[0024] The chamber 1 also has a pressure reducing means for reducing the pressure inside, specifically an exhaust port 10, to which a vacuum exhaust unit 11 consisting of a vacuum pump or the like is connected.

[0025] As shown in Figure 3, the pair of winding portions 31 and 32 of the air-core coil 3 are wound in the same direction, and the second ends 31b and 32b, which are farther from the gas flow pipe 2 in the direction of the central axis C, are short-circuited to each other via the short-circuit portion 33. Therefore, when high-frequency power is supplied from the high-frequency power source 6 to the first ends 31a and 32a, which are close to the gas flow pipe 2, a magnetic field B, a so-called alternating magnetic field, whose magnitude and direction change with time along the central axis C that passes through the center of the air-core coil 3, is formed. The high frequency power supply 6 preferably has an output frequency of 1 MHz or less.

[0026] Furthermore, since high-frequency power is supplied from the high-frequency power source 6 to the first ends 31a and 32a adjacent to the gas flow pipe 2, an electric field E whose magnitude and direction change over time is formed between the first end 31a of the winding portion 31 and the first end 32a of the winding portion 32, which face each other. Here, since the windings 31 and 32 are arranged along the side surface of the gas flow pipe 2, an electric field E parallel to the central axis C is formed at all points of the gas flow pipe 2.

[0027] Next, the operation of the plasma generating device according to the first embodiment will be described. First, the pressure inside the chamber 1 is reduced in the vacuum exhaust section 11, and then a plasma generating gas is injected from the plasma generating gas supply section 7 into the gas flow pipe 2 through the plasma generating gas inlet 4. Since the plasma generating gas inlet 4 is located in the middle of the first straight section 2C, the plasma generating gas branches into two directions inside the gas flow pipe 2 and flows through the gas flow pipe 2 in two directions. One direction passes through the first bent section 2F and the second straight section 2D and is injected from the opening end 2a of the gas flow pipe 2 along the center line T1 into the chamber 1, and the other direction passes through the second bent section 2G and the third straight section 2E and is injected from the opening end 2b of the gas flow pipe 2 along the center line T2 into the chamber 1.

[0028] In this state, high-frequency power is supplied from the high-frequency power supply 6 between the first ends 31a and 32a of the air-core coil 3 to form an alternating magnetic field along the central axis C, and a high voltage is applied to the gas flow pipe 2 by a high-voltage application device (not shown) to generate a discharge, thereby igniting plasma within the gas flow pipe 2. At this time, due to the high-frequency power supplied from the high-frequency power source 6 between the first ends 31a and 32a of the air-core coil 3, an electric field E parallel to the central axis C is formed inside the gas flow pipe 2 located between the pair of winding portions 31 and 32 of the air-core coil 3, making it easier to generate electrostatic plasma and to ignite the plasma.

[0029] The ignited plasma cannot follow the changes in the high-frequency electromagnetic field and behaves as if it were a conductive metal pillar. Electromagnetic induction causes eddy currents to flow in the plasma, and Joule heat generated by these eddy currents generates induction thermal plasma.

[0030] The induction thermal plasma Z thus generated is injected into the chamber 1 along the center lines T1 and T2 from the pair of open ends 2a and 2b of the gas flow pipe 2 in response to the flow of the plasma generating gas, as shown in FIG. 2. As shown in FIG. 2, when the substrate S is held by the substrate holder 9 and the surface of the substrate S is positioned between the point P where the center lines T1 and T2 at the opening ends 2a and 2b of the gas flow pipe 2 intersect and these opening ends 2a and 2b, the induction thermal plasmas Z that have been injected into the chamber 1 from the opening ends 2a and 2b extend and overlap each other on the surface of the substrate S so as to face each other. As a result, a closed-circuit plasma current is formed that passes through the inside of the gas flow pipe 2, along the center lines T1 and T2 extending from the pair of open ends 2a and 2b to the surface of the substrate S, and on the surface of the substrate S. As a result, the linear region connecting points A and B where center lines T1 and T2 intersect with the surface of substrate S is directly irradiated with uniform induction thermal plasma Z, making it possible to perform heat treatment on the surface of substrate S.

[0031] At this time, the raw material inlet 5, which is disposed between the pair of opening ends 2a and 2b, is located directly above the line connecting points A and B on the surface of the substrate S. Therefore, when the raw material is injected from the raw material supply unit 8 into the chamber 1 through the raw material inlet 5, the raw material is introduced into the induction thermal plasma Z formed on the surface of the substrate S and undergoes a chemical reaction, so that the surface of the substrate S is subjected to a process corresponding to the raw material.

[0032] The raw material supplied from the raw material supply unit 8 can be any of various materials such as solid, liquid, gas, or a mixture of these. Specifically, solid substances such as titanium powder and graphite powder, liquid substances such as benzene and ethanol, and gas substances such as nitrogen, oxygen and hydrogen are used depending on the purpose of each treatment. For example, by supplying nitrogen gas as a source material, a nitriding treatment can be performed on the surface of the substrate S, and by supplying oxygen gas as a source material, an oxidation treatment can be performed on the surface of the substrate S. Furthermore, by supplying various raw materials, it is also possible to form a film on the surface of the substrate S.

[0033] In addition, by modulating the amplitude of the high-frequency current supplied from the high-frequency power supply 6 between the first ends 31a and 32a of the air-core coil 3, it is possible to control the heat flux and radical flux from the induction thermal plasma Z to the substrate S in the chamber 1, which is the object to be processed.

[0034] For example, by alternately supplying two types of high-frequency currents with different amplitudes to the air-core coil 3, it is possible to maintain the surface temperature of the substrate S within a predetermined range in which the substrate S is not thermally damaged, while alternately performing two treatments with different amounts of radicals in the induction thermal plasma Z, thereby efficiently performing surface treatment of the substrate S.

[0035] As the plasma generating gas for generating the induction thermal plasma, an inert gas such as argon gas can be used.

[0036] In this embodiment 1, induction thermal plasma is generated while a plasma generating gas is flowing inside the gas flow pipe 2, and raw material is introduced into the induction thermal plasma injected into the chamber 1 from the pair of opening ends 2a and 2b of the gas flow pipe 2. Therefore, only the plasma generating gas is present inside the gas flow pipe 2, and it is possible to obtain an extremely stable induction thermal plasma even when raw material is supplied.

[0037] Here, an experiment on the generation of induction thermal plasma, which was carried out using an actual plasma generating device, will be described.

[0038] The plasma generating device was manufactured with the length L1 of the first straight portion 2C set to 100 mm, the length L2 of the second straight portion 2D and the third straight portion 2E set to 20 mm, and the connection angles θ1 and θ2 set to 45 degrees. The distance between the pair of open ends 2a and 2b is approximately 80 mm.

[0039] First, the inside of the chamber 1 is depressurized by the vacuum exhaust unit 11 to a pressure of 1330 Pa (N / m 2 ) and the plasma generating gas flow rate was 1 liter / min (1.667 x 10 -5 m 3 Argon gas at a flow rate of 1000 s / sec was supplied from plasma generating gas inlet 4 into gas flow pipe 2, and high frequency power of 6 kW and 295 kHz was supplied from high frequency power supply 6 to air-core coil 3 to generate plasma. From the light emission state of the argon gas, it was confirmed that stable induction thermal plasma Z had been formed inside gas flow pipe 2 and on center lines T1 and T2 extending from the pair of open ends 2a and 2b.

[0040] Furthermore, by placing the substrate S close to the pair of open ends 2a and 2b, it was possible to irradiate the induction thermal plasma Z onto the surface of the substrate S over a linear area of ​​approximately 80 mm x 10 mm. However, the plasma generating device produced in the above experiment is merely an example. For example, if the length L1 of the first straight section 2C of the gas flow pipe 2 is set to about 250 mm, the induction thermal plasma Z can be irradiated onto the surface of the substrate S over an area of ​​about 200 mm x 10 mm. That is, by lengthening the first straight portion 2C of the gas flow pipe 2 and widening the gap between the pair of open ends 2a and 2b, it is possible to make the irradiation area of ​​the substrate S with the induction thermal plasma Z longer.

[0041] Since an air-core coil 3 without a core is used, a raw material inlet 5 can be placed between a pair of winding portions 31 and 32 of the air-core coil 3, and the raw material can be directly injected into the chamber 1 from the raw material inlet 5. Therefore, even if the source material contains short-lived active species that would disappear before reaching chamber 1 if injected through plasma generating gas inlet 4 located in the middle of gas flow pipe 2, it can be reliably introduced into induction thermal plasma in chamber 1.

[0042] Furthermore, since no core is used, there is no need to consider the problems of magnetic saturation and iron loss, and furthermore, cooling of the core is not required, thereby realizing a plasma generating device with a simple configuration.

[0043] The chamber 1 and the gas flow pipe 2 are preferably made of a material with excellent heat resistance, such as quartz or ceramics.

[0044] The outer periphery of the air-core coil 3, particularly the outer periphery of the winding portions 31 and 32, is preferably coated with an anti-discharge coating to prevent discharge between adjacent windings.

[0045] Furthermore, it is preferable to use a coil having a structure that allows cooling by circulating cooling water inside. Alternatively, a structure may be adopted in which the chamber 1, the gas flow pipe 2, and the air-core coil 3 are cooled by being exposed to flowing water in a water-cooled tank.

[0046] In addition, high-temperature induction thermal plasma is also formed inside the gas flow pipe 2, but by increasing the flow rate of the plasma generating gas injected from the plasma generating gas inlet 4, it is possible to prevent the induction thermal plasma from coming into contact with the inner wall of the gas flow pipe 2.

[0047] Furthermore, although the case where the connection angle θ1 and the connection angle θ2 are both 45 degrees has been exemplified, it is preferable that the connection angle θ1 and the connection angle θ2 are both 45±10 degrees. If the angle is less than 35 degrees, as shown in FIG. 4, the induction thermal plasma Z is likely to move away from the substrate S and come into contact with the upper surface of the rectangular parallelepiped portion of the chamber 1 near the center. It is presumed that this is probably because the gas flows ejected from the open ends 2a and 2b collide with each other near the center of the substrate S.

[0048] Conversely, if the connection angle θ1 and the connection angle θ2 are greater than 55 degrees, the induction thermal plasma cannot be generated stably. In the device described in Patent Document 2, the connection angles θ1 and θ2 are approximately 90 degrees, while in the device described in Non-Patent Document 1, the connection angles θ1 and θ2 are approximately 60 degrees, but it is said that induction thermal plasma can be generated stably. The difference is likely due to the operating pressure and driving frequency of the device. When plasma is generated in a state where the apparatus is depressurized, more specifically, when plasma is generated in a state where the pressure in the chamber is depressurized to 10,000 Pa or less, and / or when the frequency of the high frequency power is 1 MHz or less, more specifically, when the frequency of the high frequency power is 100 kHz or more and 1 MHz or less, the connection angle θ1 and the connection angle θ2 should both be 45±10 degrees.

[0049] Furthermore, the chamber 1 may be configured so that the substrate holder 9 can move together with the substrate S relative to the pair of opening ends 2a and 2b of the gas flow pipe 2, and linear induction thermal plasma may be irradiated successively to all parts of the substrate S, thereby enabling plasma processing to be performed on the entire surface of the substrate S.

[0050] Next, a second embodiment (example 2) will be described. The configuration of the second embodiment is shown in FIG. Ar (flow rate: 1.0 slpm) was injected from a plasma generating gas inlet provided in the center of the upper part of the gas flow pipe 2 . In this Example 2, two inlets for introducing raw materials were provided in the chamber, and the raw materials were sprayed onto the substrate through a porous ceramic. The source materials were Ar / N2 with a flow rate of 0.6 / 0.1 slpm. In Example 2, a three-pattern coil was used as the air-core coil 3, and Ar / N2 plasma was generated and maintained with an input power of 6 kW and a chamber pressure of 10 Torr.

[0051] The light emission pattern of the Ar / N2 induction thermal plasma (ICTP) in this state is shown in Figure 6. A short, purplish light emission was observed in the space above the substrate holder. This is N 2+ This is thought to be due to the emission spectrum (355 to 430 nm) of Spectroscopic observation also confirmed the emission spectra of N atoms at 747.3 and 821.1 nm. Figure 7 shows the distribution of the N atomic spectrum (821.1 nm) in the x direction at 21 points spaced 1 mm apart on the substrate holder. It can also be seen from the x-direction distribution diagram of the N atom spectrum (821.1 nm) in FIG. 7 that the spectral intensity distribution of the plasma generator according to the present invention is uniform. [Explanation of symbols]

[0052] 1 chamber 2 Gas distribution pipes 2a,2b Open end 3 Air-core coil 4. Plasma generating gas inlet 5 Raw material inlet 6 High frequency power supply 7. Plasma generating gas supply unit 8 Raw material supply section 9 Board holding part 10 exhaust port 11 Vacuum exhaust section 31,32 Winding section 31a, 32a First end 31b, 32b Second end 33 Short circuit C center axis 2C First straight section 2D second straight section 2E Third straight section 2F First bending section 2G Second bending part θ1 Connection angle between the first straight portion and the second straight portion θ2 Connection angle between the first straight section and the third straight section T1,T2 center line P: Point where the center lines intersect S board B magnetic field E electric field Z induction thermal plasma A,B The point where the center line intersects with the board surface

Claims

1. a chamber; a gas flow pipe having open ends on both sides communicating with the chamber, the gas flow pipe has a first straight portion, and second and third straight portions that are connected to both sides of the first straight portion via bends at predetermined connection angles θ1 and θ2 inward, and the open ends are located at the ends of the second and third straight portions, a pair of air-core coils disposed opposite each other on both sides of the gas flow pipe; a high frequency power source that supplies high frequency power to the air-core coil to generate induction thermal plasma while a plasma generating gas is flowing through the gas flow pipe; The plasma generating device is characterized in that the connection angles θ1 and θ2 are 45±10 degrees.

2. 2. The plasma generating apparatus according to claim 1, further comprising a pressure reducing means for reducing the pressure inside the chamber.

3. 2. The plasma generating device according to claim 1, wherein the high frequency power source has an output frequency of 1 MHz or less.

4. A method for plasma treating a substrate, characterized by using the plasma generator according to any one of claims 1 to 3.

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