Microwave plasma generating device, microwave plasma processing device, and microwave plasma processing method

Abstract

Provided is a microwave plasma generation device capable of generating uniform plasma without causing microwave interference between plasma generators, and without destroying other microwave generation sources. The microwave plasma generating device is provided with a plurality of microwave plasma generators. Each of the microwave plasma generators is provided with a cylindrical container formed from a dielectric, a cylindrical chamber disposed so as to cover the cylindrical container, a gas supply port provided at one end of the cylindrical container, and a microwave guide inlet provided at the side of the cylindrical chamber. A metal tube is arranged at the other end of the cylindrical container, the metal tube is used for discharging reactive gas generated by the reaction of the gas and the plasma, the inner diameter of the metal tube is more than 0.1 mm and less than half of the wavelength of the used microwave, and the ratio L2 / R2 of the axial length L2 and the inner diameter R2 of the metal tube is more than 0.5.

Description

Technical Field

[0001] The present invention relates to a microwave plasma generator for generating plasma using microwaves, a microwave plasma processing device using the microwave plasma generator, and a method for performing microwave plasma processing. Background Art

[0002] In semiconductor manufacturing processes, plasma processing is often used for etching of semiconductor substrates, film formation, etc. As a plasma processing apparatus for performing such plasma processing, attention has been paid to microwave plasma processing apparatuses that can uniformly form high-density and low-temperature electrons.

[0003] The microwave plasma processing device has a microwave excitation plasma source that excites plasma with microwaves of a wavelength of several hundred MHz to several tens of GHz. Compared with a high-frequency plasma source, etc., the plasma potential is lower, so it is widely used for lossless resist ashing, anisotropic etching with applied bias voltage, etc.

[0004] In order to perform plasma treatment on a large-area wafer, for example, it is necessary to make the plasma source larger. Patent document 1 (JPH07-332165A) discloses a plasma processing device. In the plasma processing device, a cylindrical container has an inner diameter capable of accommodating a large-diameter wafer of more than 8 inches and is formed of a conductive material capable of transmitting microwaves. The interior of the cylindrical container is divided by a disc-shaped microwave transmission component, so that one side of the cylindrical container is a reduced-pressure atmosphere, and the other side of the cylindrical container is connected to a microwave waveguide. The surface of the reduced-pressure atmosphere side of the microwave transmission component is located near the distance within n / 2 times the wavelength of the microwave in the tube from the end face of the cylindrical container connected to the microwave waveguide. Patent document 1 states that the plasma processing device can cope with large-diameter samples of more than 8 inches, and can improve the speed and uniformity of sample processing.

[0005] However, the plasma processing device described in Patent Document 1 needs to be equipped with a plasma generator that can generate plasma using a high-frequency source with huge power. The plasma generator driven by such huge power has a problem of poor energy efficiency and thus significantly reduced production efficiency. In addition, due to the high power, the electric field leakage is large, which may cause damage to the processed substrate.

[0006] As a microwave plasma generator with a simple structure, Patent Document 2 (WO03 / 096769A1) discloses a microwave plasma generator, which introduces microwaves from the side into a cylindrical single-layer container formed of a dielectric material, so that the cylindrical container forms a dielectric line with an infinite length and suppresses the reflection of the introduced microwaves, thereby eliminating the need for an impedance matcher. The cylindrical microwave plasma generator described in Patent Document 2 has a high plasma density, can shorten the processing time, and is inexpensive due to its simple structure.

[0007] When a large-area wafer is to be subjected to plasma treatment using the microwave plasma generator described in Patent Document 2, a plurality of microwave plasma generators can be arranged side by side. However, when such a plurality of plasma generators are arranged side by side, interference occurs between the plurality of microwave generators included in each plasma generator, and a uniform plasma cannot be generated. In addition, there is a case where microwaves generated from one microwave source destroy another microwave source.

[0008] Prior art literature

[0009] Patent Literature

[0010] Patent Document 1: JPH07-332165A

[0011] Patent document 2: WO03 / 096769A1 Summary of the invention

[0012] Therefore, an object of the present invention is to provide a microwave plasma generator in which microwave interference does not occur between plasma generators, a uniform plasma can be generated, and other microwave generating sources are not damaged. Also, an object of the present invention is to provide a microwave plasma processing device using the microwave plasma generator and a method for performing microwave plasma processing using the microwave plasma processing device.

[0013] In view of the above-mentioned purpose, the inventors of the present application conducted in-depth research and found that by providing a metal tube with the same diameter as the end of the cylindrical container or an inner diameter smaller than the inner diameter of the cylindrical container at the front section of the cylindrical container formed by a dielectric, it is possible to reduce the leakage of microwaves to the processed object, generate uniform plasma, and prevent damage to other microwave generating sources, thereby conceiving of the present invention.

[0014] That is, the microwave plasma generating device of the present invention comprises a plurality of microwave plasma generators, each of which comprises: a cylindrical container formed of a dielectric; a cylindrical chamber arranged on the outer side of the cylindrical container in a manner covering the cylindrical container; a gas supply port provided at one end of the cylindrical container for supplying gas into the cylindrical container; and a microwave introduction port provided on the side of the cylindrical chamber; each microwave plasma generator generates plasma along the inner surface of the cylindrical container, and the microwave plasma generating device is characterized in that it comprises a discharge portion connected to the other end of the cylindrical container for discharging a reactive gas generated by a reaction between the gas and the plasma, and the discharge portion comprises a conductive tube on the inner side, and the conductive tube has a reduced diameter compared to the other end of the cylindrical container.

[0015] More specifically, the conductive tube of the discharge portion is formed by a metal tube connected to the other end of the cylindrical container and satisfies any of the following conditions:

[0016] (1) The inner diameter of the metal tube is 0.1 mm or more and less than half the wavelength of the microwave used, and the ratio L2 / R2 of the axial length L2 of the metal tube to the inner diameter R2 is 0.5 or more;

[0017] (2) the inner diameter of the metal tube is less than the inner diameter of the cylindrical container, and the ratio L2 / R2 of the axial length L2 of the metal tube to the inner diameter R2 is greater than 0.5; or

[0018] (3) The inner diameter of the metal tube is 0.1 mm or more and 65% or less of the inner diameter of the cylindrical container.

[0019] The microwave plasma generator of the present invention can uniformly perform plasma treatment on a processed object such as a large-area substrate, and has a small and simple unit structure, so that the energy of microwaves can be used efficiently. In addition, the damage caused by plasma to the processed object (substrate, etc.) can be reduced. Therefore, the microwave plasma generator of the present invention, the microwave plasma processing device using the microwave plasma generator, and the microwave plasma processing method are particularly suitable for etching treatment, film forming treatment, etc. of semiconductor substrates.

[0020] The microwave plasma processing apparatus of the present invention is characterized by comprising: the microwave plasma generator; and a sample processing chamber connected to the microwave plasma generator and supplied with the reactive gas generated in the microwave plasma generator.

[0021] The microwave plasma processing method of the present invention is a method for processing the object to be processed using the microwave plasma processing device, characterized in that: gas is supplied from the gas supply port set in the cylindrical container of the microwave plasma generating device equipped with the multiple microwave plasma generators, and microwaves are introduced from the microwave introduction port set on the side of the cylindrical chamber, plasma is generated inside the cylindrical container, reactive gas generated by the reaction of the gas and the plasma is supplied to the sample processing chamber connected to the cylindrical container, and the supplied gas and the processed reactive gas are discharged from the gas exhaust port set in the sample processing chamber, and the object to be processed held on the holding table in the sample processing chamber is irradiated with the reactive gas, thereby processing the object to be processed.

[0022] The microwave plasma treatment method of the present invention is a method for treating the object to be treated using a microwave plasma treatment device, wherein the microwave plasma treatment device includes a microwave plasma generator, and the microwave plasma generator includes a plurality of microwave plasma generators. The microwave plasma treatment method is characterized in that the microwave plasma generator includes a cylindrical container formed of a dielectric, a cylindrical chamber arranged in a manner to cover the cylindrical container from the outside, a gas supply port provided at one end of the cylindrical container and supplying gas into the cylindrical container, a microwave introduction port provided on the side of the cylindrical chamber, a discharge portion connected to the other end of the cylindrical container and discharging a reactive gas generated by a reaction between the gas and the plasma includes a conductive tube on the inside, the conductive tube has a reduced diameter compared to the other end of the cylindrical container, gas is supplied from the gas supply port provided in the cylindrical container of the microwave plasma generator including the plurality of microwave plasma generators, and microwaves are introduced from the microwave introduction port provided on the side of the cylindrical chamber, plasma is generated inside the cylindrical container, and the reactive gas is discharged from the cylindrical container. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a perspective view schematically showing an example of the microwave plasma processing apparatus of the present invention.

[0024] Figure 2a yes Figure 1 A-A cross-sectional view of a microwave plasma processing device, Figure 2b yes Figure 2a B-B section view.

[0025] Figure 3 yes Figure 1 Top view of a microwave plasma processing device.

[0026] Figure 4a This is a schematic diagram showing an example of a plurality of microwave plasma generators arranged in the microwave plasma generating device of the present invention as viewed along the axial direction. Figure 4b This is a schematic diagram showing another example of a plurality of microwave plasma generators arranged in the microwave plasma generating apparatus of the present invention as viewed along the axial direction. Figure 4c This is a schematic diagram showing another example of a plurality of microwave plasma generators arranged in the microwave plasma generating device of the present invention as viewed along the axial direction.

[0027] Figure 5 It is a graph showing the electric field on the surface of the object to be processed when the inner diameter and the axial length of the metal tube are changed in the microwave plasma processing apparatus of the present invention.

[0028] Figure 6 It is a cross-sectional view for explaining a microwave plasma processing apparatus according to a modified example. DETAILED DESCRIPTION

[0029] [1] Microwave plasma processing equipment

[0030] Figure 1 , Figure 2a and Figure 2b An example of the microwave plasma processing device 100 of the present invention is shown, and the microwave plasma processing device 100 is composed of the microwave plasma generating device 101 of the present invention and the sample processing chamber 102, and the sample processing chamber 102 is connected to the microwave plasma generating device 101 and is configured in a manner of being supplied with the reactive gas GA generated in the microwave plasma generating device 101. It should be noted that, Figure 1 The microwave plasma generator 101 a is shown only by the cylindrical container 103 , the cylindrical chamber 109 , and the microwave introduction port 105 , and the holding table 107 and the like in the sample processing chamber 102 are omitted.

[0031] Figure 3 Yes means Figure 1 The top view of the microwave plasma generator 101 shown in FIG. 1 includes a magnetron 50 and the like attached to the microwave plasma generator 101 a .

[0032] (1) Microwave plasma generator

[0033] The microwave plasma generating device 101 is characterized in that it has a plurality of ( Figure 1There are three microwave plasma generators 101a, each of which uses microwaves to generate plasma along the inner surface of the cylindrical container 103. The microwave plasma generator 101a includes: a cylindrical container 103, which is formed of a dielectric; a cylindrical chamber 109, which is arranged on the outside of the cylindrical container 103 in a manner covering the cylindrical container 103; a gas supply port 104, which is provided at one end 103a of the cylindrical container 103 and supplies gas into the cylindrical container 103; a microwave introduction port 105, which is provided on the side of the cylindrical chamber 109; the microwave plasma generator 101 has a microwave inlet 105 at the other end 103b of the cylindrical container 103 for releasing reactive gas generated by the reaction of the gas G with the plasma. The gas GA discharge portion 112 is formed by a metal tube 112a connected to the other end 103b of the cylindrical container 103, and is characterized in that it satisfies any one of the following conditions 1: (i) the inner diameter R2 of the metal tube 112a is greater than 0.1 millimeters (mm), less than half the wavelength of the microwave used, or less than the inner diameter of the cylindrical container 103, and the ratio L2 / R2 of the axial length L2 of the metal tube 112a to the inner diameter R2 is greater than 0.5, or (ii) the inner diameter R2 of the metal tube 112a is greater than 0.1 mm and less than 65% of the inner diameter of the cylindrical container 103.

[0034] like Figure 3 As shown, a magnetron 50 is connected to the microwave introduction port 105 of each microwave plasma generator 101a. These magnetrons 50 operate under the control of the power supply control device 80. With respect to the center C of the microwave plasma generator 101, the reference axes X1 to X3 where the chamber 109 or the container 103 is arranged are evenly arranged around the center C, and the angles α1 to α3 are equal, and the distance from the center C to the container 103 is also equal. In the example shown in the figure, the direction in which the microwave introduction port 105 extends from the container 103 is parallel to the reference axes X1 to X3, but from the viewpoint of sufficiently ensuring the space for arranging the magnetron 50 by avoiding interference, the direction in which the microwave introduction port 105 extends relative to the reference axes X1 to X3 in a plan view may be within a predetermined angle range β. Here, when the number of microwave plasma generators 101a evenly arranged around the center C is n, the angle range β is set to, for example, 360° / n, preferably 360° / 2n, but is not limited thereto.

[0035] In the microwave plasma generator 101a, gas G (for example, hydrogen) is supplied from the gas supply port 104 to the cylindrical container 103 maintained in a reduced pressure state, and microwaves M are introduced from the microwave introduction port 105 provided on the side of the cylindrical chamber 109. The microwaves use the surface of the cylindrical container 103 as a transmission path to generate standing waves, and the microwaves that penetrate the cylindrical container 103 generate plasma of the gas G in the cylindrical container 103. The generated plasma and / or the reactive gas GA (plasma of the gas G, free radicals, etc.) generated by the reaction with the plasma are discharged from the metal tube 112a of the discharge portion 112 provided at the other end 103b along the flow of the supplied gas G, and are introduced into the sample processing chamber 102 connected thereto. Here, the metal tube 112a is a conductive tube CT whose inner diameter is reduced compared to the other end 103b of the cylindrical container 103. That is, when the cylindrical container 103 is a perfect circle, the inner diameter of the conductive tube CT, that is, the metal tube 112a, is smaller than the inner diameter of the other end 103b. In addition, the axial length of the conductive tube CT is more than half of the inner diameter of the metal tube 112a.

[0036] (a) Overall composition

[0037] like Figure 2a As shown, the microwave plasma generator 101a is configured so that the discharge portion 112 provided at the other end 103b is opposite to the object to be processed 106 in the sample processing chamber 102 at the interface between the microwave plasma generator 101 and the sample processing chamber 102. In the accompanying drawings, each microwave plasma generator 101a is configured so that the axial direction of the cylindrical container 103 is orthogonal to the interface, but it is not necessary to configure it in this way. It can be configured with an inclination of more than 30° and less than 90° based on the direction parallel to the interface. The inclination angles of each microwave plasma generator 101a can be the same or different. By configuring the microwave plasma generator 101a in an inclined manner in this way, when the reactive gas is irradiated on the object to be processed 106 arranged in the sample processing chamber 102, the reactive gas can be irradiated in a wider range because the shape of the reactive gas is diffused in the inclined direction.

[0038] The axial directions of the cylindrical containers 103 of the plurality of microwave plasma generators 101a may be parallel to each other or may not be parallel to each other. In particular, when the microwave plasma generators 101a are arranged to be tilted relative to the interface, it is preferred that the tilt angles of the microwave plasma generators 101a are consistent but the tilt directions are different, or the tilt angles of the microwave plasma generators 101a are different and the directions are also dispersed. Figure 2a In the embodiment, the cylindrical container 103 and the cylindrical chamber 109 are partially connected to the sample processing chamber 102 , but the opening of the metal tube 112 a may be connected to the sample processing chamber 102 .

[0039] Each microwave plasma generator 101a may have the same structure or different structures. For example, the inner diameter, wall thickness or length of the cylindrical container 103, the position of the microwave inlet 105, the output power of the microwave generator (especially the magnetron 50), the shape of the discharge portion 112, the diameter or length of the metal tube 112a, etc. may be different. In addition, the number of microwave plasma generators 101a is not particularly limited and may be more than two. Although there is no upper limit, it is preferred that the number of microwave plasma generators 101a is 100 cm2 per 100 cm2 according to the treatment surface. 2 The number is ten or less, more preferably five or less, and even more preferably two or less.

[0040] Figures 4a to 4c The plurality of microwave plasma generators 101a and 101b arranged in the microwave plasma generating device 101 are schematically shown when viewed along the axial direction. Figures 4a to 4c In the figure, each microwave plasma generator 101a, 101b is simply represented by a circle. Figure 4a The structure shown is a configuration of four microwave plasma generators 101a of the same diameter (large diameter). Figure 4b 1 shows a structure in which four large-diameter microwave plasma generators 101a and three small-diameter microwave plasma generators 101b are configured. Figure 4c The structure shown is that twelve microwave plasma generators 101b having the same diameter (small diameter) are arranged.

[0041] As shown in these examples, by arranging a plurality of microwave plasma generators side by side, the generated plasma can be uniformly irradiated onto a wide range of objects to be processed. The arrangement pattern of the plurality of microwave plasma generators arranged in the microwave plasma generating device 101 is not limited to these examples, as long as the generated plasma can be uniformly irradiated onto the object to be processed.

[0042] (b) Structure of the discharge section

[0043] The discharge portion 112 is formed by a metal tube 112a connected to the other end 103b of the cylindrical container 103. The inner diameter of the metal tube 112a as the conductor tube CT is smaller than the inner diameter of the other end 103b of the cylindrical container 103. More specifically, the inner diameter R2 of the metal tube 112a satisfies any of the following conditions:

[0044] (i) the inner diameter R2 of the metal tube 112a is 0.1 mm (millimeter) or more and less than half the wavelength of the microwave used or less than the inner diameter of the cylindrical container 103, and the ratio L2 / R2 of the axial length L2 of the metal tube 112a to the inner diameter R2 is 0.5 or more; or

[0045] (ii) The inner diameter R2 of the metal tube 112 a is not less than 0.1 mm and not more than 65% of the inner diameter of the cylindrical container 103 .

[0046] Regarding condition (i), the inner diameter R2 of the metal tube 112a is greater than 0.1 mm and less than half the wavelength of the microwave used or less than the inner diameter of the cylindrical container 103. For example, when a microwave with a frequency of 2.45 GHz (wavelength = about 122 mm) is used, the inner diameter R2 of the metal tube 112a is less than 61 mm. In the case where the inner diameter of the cylindrical container 103 is greater than half the wavelength of the microwave used, the upper limit of the inner diameter R2 of the metal tube 112a is the inner diameter of the cylindrical container 103. In addition, the ratio L2 / R2 of the axial length L2 of the metal tube 112a to the inner diameter R2 is greater than 0.5. By adopting such a structure, microwave interference will not occur between the plasma generating devices, uniform plasma can be generated, and damage to other microwave generating sources can be prevented. The ratio L2 / R2 is more preferably greater than 1, further preferably greater than 1.5, and most preferably greater than 2.

[0047] When the ratio L2 / R2 is 0.5 or more, the inner diameter R2 of the metal tube 112a is preferably 2 to 100% of the inner diameter of the cylindrical container 103, more preferably 10 to 90%, further preferably 20 to 80%, and further preferably 30 to 70%. In particular, in consideration of (ii) described later, the inner diameter R2 of the metal tube 112a is preferably greater than 65% of the inner diameter of the cylindrical container 103. Furthermore, the axial length L1 of the cylindrical container 103 is preferably 4 to 1000% of the inner diameter R1 of the cylindrical container 103, more preferably 20 to 500%, further preferably 40 to 300%, and most preferably 60 to 200%.

[0048] Regarding condition (ii), regardless of the value of the above ratio L2 / R2, the inner diameter R2 of the metal tube 112a is greater than 0.1 mm and less than 65% of the inner diameter of the cylindrical container 103. By adopting such a configuration, microwave interference will not occur between the plasma generating devices, uniform plasma can be generated, and damage to other microwave generating sources can be prevented. The inner diameter R2 of the metal tube 112a is preferably less than 60% of the inner diameter of the cylindrical container 103, more preferably less than 55%, and most preferably less than 50%. In addition, the lower limit of the inner diameter R2 of the metal tube 112a is preferably 2% of the inner diameter of the cylindrical container 103, more preferably 10%, further preferably 20%, and most preferably 30%.

[0049] It is sufficient for the above conditions (i) and (ii) to be satisfied, but it is also possible for both conditions to be satisfied.

[0050] When the inner diameter R2 of the metal tube 112a is smaller than the inner diameter R1 of the cylindrical container 103, the metal tube 112a is connected to the other end 103b of the cylindrical container 103 via the connecting member 112b. The connecting member 112b covers the other end 103b of the cylindrical container 103 and has a hole in the center thereof to which the metal tube 112a is connected. The connecting member 112b preferably has a disk shape or a conical shape.

[0051] The metal tube 112a is preferably made of at least one selected from stainless steel, aluminum, and aluminum alloy.

[0052] (c)Tubular container

[0053] The cylindrical container 103 is preferably made of a material having excellent corrosion resistance to plasma, for example, quartz glass (relative dielectric constant 3.9), alumina (relative dielectric constant 9.0), boron nitride (relative dielectric constant 14), or aluminum nitride (relative dielectric constant 8.5).

[0054] The cylindrical container preferably has an inner diameter of 10 to 300 mm and a thickness of 1 to 100 mm, more preferably has an inner diameter of 20 to 100 mm and a thickness of 10 to 50 mm, and most preferably has an inner diameter of 30 to 80 mm and a thickness of 15 to 30 mm. The present invention is applicable to such a relatively small microwave plasma generator.

[0055] (d) Cylindrical chamber

[0056] The cylindrical chamber is preferably made of at least one selected from stainless steel, aluminum, and aluminum alloy.

[0057] (e) Others

[0058] The gap 110 between the cylindrical container 103 and the cylindrical chamber 109 may be a void (vacuum), but is preferably filled with a dielectric material. The dielectric material contains air. By filling the gap 110 with the dielectric material, it is possible to suppress the reflection of microwaves at the interface between the cylindrical container 103 and the external air, etc., and the microwaves can be fully transmitted to the inside of the cylindrical container 103, and the plasma generation efficiency is improved, and as a result, the processing efficiency can be improved.

[0059] At the microwave introduction port 105 of the microwave plasma generator 101, the microwave is irradiated almost vertically to the dielectric material 110 and the cylindrical container 103 and is reflected, so the utilization efficiency of the microwave is reduced. In order to prevent such a reduction in utilization efficiency, it is preferred to set a microwave anti-reflection structure 113 at the portion where the microwave introduction port 105 is connected to the cylindrical chamber 109. As the anti-reflection structure 113, for example, a structure in which nano-scale micro-protrusions are arranged in large quantities at constant intervals, a so-called moth-eye structure, can be used. In addition, a low dielectric constant material layer can be provided.

[0060] (2) Sample processing room

[0061] The sample processing chamber 102 is connected to the microwave plasma generator 101 and is supplied with the reactive gas GA generated in each microwave plasma generator 101a. The sample processing chamber 102 is provided with: a holding table 107 for holding the object to be processed 106 arranged in a manner that the reactive gas GA generated in the microwave plasma generator 101 can be irradiated; and a gas discharge port 108, which discharges the supplied gas G and the processed reactive gas GA. The holding table 107 is rotatably arranged around a predetermined rotation axis R. The rotation axis R and the central axis C of the cylindrical container 103 can be tilted at a predetermined angle. The holding table 107 preferably has a temperature control function.

[0062] The position of the gas outlet 108 is not particularly limited, but is preferably located downstream of the holding table 107, that is, behind the holding table 107 when viewed from the microwave plasma generator 101. In particular, it is preferably located on the side of the holding table 107 opposite to the side where the workpiece 106 is disposed.

[0063] The inner surface of the processing chamber is preferably treated with hard aluminate to prevent corrosion by reactive gases.

[0064] [2] Microwave plasma treatment method

[0065] The microwave plasma processing method of the present invention uses a microwave plasma processing device 100 (for example Figure 1 , Figure 2a , Figure 2b The microwave plasma processing method of the present invention is carried out by using a microwave plasma processing device 100 having the microwave plasma generator 101 and a sample processing chamber 102 connected thereto. That is, the microwave plasma processing method of the present invention is characterized in that a gas G is supplied from a gas supply port 104 provided in a cylindrical container 103 of the microwave plasma generator 101 having a plurality of microwave plasma generators 101a, and microwaves M are introduced from a microwave introduction port 105 provided on the side of a cylindrical chamber 109, plasma is generated inside the cylindrical container 103, a reactive gas GA generated by a reaction between the gas G and the plasma is supplied to the sample processing chamber 102 connected to the cylindrical container 103, and the supplied gas G and the processed reactive gas GA are exhausted from an exhaust port 108 provided in the sample processing chamber 102, and the processing of the processing object 106 is performed by irradiating the reactive gas GA onto the processing object 106 held on a holding table 107 in the sample processing chamber 102.

[0066] The microwave plasma treatment is performed, for example, in the following manner: a gas G (e.g., hydrogen) is supplied from a gas supply port 104 to a cylindrical container 103 maintained at a pressure of 1 Torr or less at a flow rate of 0.1 to 10 sccm (standard cubic centimeter per minute), and a microwave M with an output power of 100 to 2000 W (watts) (e.g., 2450 MHz and 800 W) is introduced from a microwave inlet 105, and a cylindrical reactive gas GA is generated in the cylindrical container 103 by the microwaves in a standing wave state in the cylindrical container 103, and a holding table 107 is rotated while irradiating a workpiece 106 maintained at 0 to 400° C. for 1 to 20 minutes with a density of 5×10 14 Pieces / cm 3 The above-mentioned free radical reactive gas GA. Thus, the product of the irradiation time and the density of the free radicals on the processed object 106 can be made 25×10 14 Points·pieces / cm 3 The potential difference between the reactive gas GA and the surface of the treated object 106 is preferably 10 V or less. The treated reactive gas GA and the residual gas G are discharged from the gas outlet 108. It should be noted that the irradiation density of the free radicals can be determined by a known method (T.Arai et al. (2016) "Selective Heating of Transition Metal UsingsHydrogen Plasma and Its Application to Formation of Nickel Silicide Electrodes for Silicon Ultralarge-Scale Integration Devices" Journal of Materials Science and Chemical Engineering, 2016, 4, 29-33).

[0067] In the above description, the microwaves M introduced from the microwave introduction port 105 may be supplied continuously or in pulses. When the microwaves M are supplied in pulses, the microwaves M may be supplied sequentially to the three cylindrical containers 103 at a predetermined time difference, and at this time, the pulses sequentially supplied at a predetermined time difference may or may not overlap each other in time.

[0068] The specific processing performed by the microwave plasma processing device 100 includes film formation, etching, and ashing. For example, in the case of forming a SiO2 film or ashing a resist, oxygen is used as the processing gas G, for example, from the viewpoint of generating oxygen radicals. Depending on the purpose of the processing, a gas other than oxygen (for example, nitrogen, hydrogen, carbon dioxide, ammonia, a rare gas (helium, neon, argon, etc.) can be used as the processing gas G. For example, in the case of etching Si, CF4 and CF6 are used to generate fluorine radicals.

[0069] The pressure in the cylindrical container, or in the cylindrical container and the cylindrical chamber is preferably maintained at 10 Torr or less, more preferably maintained at 1 mTorr to 10 Torr, and most preferably maintained at 10 mTorr to 1 Torr.

[0070] The gas supply rate is preferably 0.01 to 1000 sccm, more preferably 0.1 to 500 sccm, and most preferably 0.5 to 5 sccm. If the gas supply rate is less than 0.01 sccm, the reactive gas concentration cannot be increased, and if the gas supply rate is greater than 100 sccm, the exhaust rate is insufficient and the pressure becomes unstable.

[0071] The gas exhaust rate is preferably 1 to 10,000 L / min (liters / minute), more preferably 10 to 2,000 L / min, and further preferably 50 to 1,000 L / min. If the gas exhaust rate is less than 1 L / min, the exhaust time is too long, and if the gas exhaust rate is greater than 10,000 L / min, the cost is too high.

[0072] The microwave output power is preferably 10 to 10,000 W, more preferably 100 to 1,000 W, and most preferably 200 to 700 W. If the microwave output power is less than 10 W, the reactive gas generation becomes too small, and if the microwave output power is greater than 10,000 W, the cost is too high.

[0073] The treatment time is preferably 0.001 to 100 minutes, more preferably 0.01 to 50 minutes, and further preferably 0.05 to 20 minutes. If the treatment time is shorter than 0.001 minutes, the effect becomes too small, and if the treatment time is longer than 100 minutes, the productivity decreases.

[0074] The rotation speed of the holding table is preferably 0.1 to 10000 rpm, more preferably 1 to 1000 rpm, and even more preferably 10 to 200 rpm. If the rotation speed is slower than 0.1 rpm, unevenness occurs, and if the rotation speed is faster than 10000 rpm, mechanical durability decreases.

[0075] Example

[0076] The present invention is described in more detail by the following examples, but the present invention is not limited thereto.

[0077] [Example 1]

[0078] like Figure 1 As shown in FIG. 1 , a model of a microwave plasma processing device having three microwave plasma generators was constructed to calculate the amount of electromagnetic waves leaking to a workpiece disposed in a sample processing chamber. The structure of the microwave plasma generating device is as follows.

[0079] ●Microwave plasma generator (all three are of the same shape)

[0080] <Tubular container>

[0081] Material: quartz glass; outer diameter: 50mm; inner diameter: 46mm; axial length: 200mm.

[0082] <Cylindrical Chamber>

[0083] Material: stainless steel; outer diameter: 100mm; inner diameter: 80mm; axial length: 250mm.

[0084] <Metal pipe>

[0085] Material: stainless steel; inner diameter and axial length: listed in Table 1.

[0086] <Configuration of microwave plasma generator>

[0087] Center distance: 120 mm (arrangement of vertices of an equilateral triangle with a side of 120 mm)

[0088] ●Processing conditions:

[0089] Distance from metal tube to the object to be processed: 50mm;

[0090] Pressure in the cylindrical chamber: 200mTorr;

[0091] Gas: hydrogen; gas flow rate: 10sccm;

[0092] Microwave frequency: 2.45GHz (wavelength: about 122mm); output power: 500W.

[0093] Using this model and changing the inner diameter and axial length of the metal tube as shown in Table 1, the electric field on the surface of the treated object was obtained. The results are shown in Tables 1 and Figure 5 shown.

[0094] [Table 1]

[0095]

[0096] According to Table 1, it is clear that (i-1) when the inner diameter of the metal tube is less than half the wavelength of the microwave used (122 mm), and the ratio L2 / R2 of the axial length L2 of the metal tube to the inner diameter R2 is greater than 0.5, (i-2) when the inner diameter of the metal tube is less than the inner diameter of the cylindrical container, and the ratio L2 / R2 of the axial length L2 of the metal tube to the inner diameter R2 is greater than 0.5, or (ii) when the inner diameter R2 of the metal tube is greater than 0.1 mm and less than 65% of the inner diameter of the cylindrical container, the electric field on the substrate surface is significantly reduced. Therefore, it is expected that microwave interference between the plasma generating devices does not occur, uniform plasma can be generated, and other microwave generating sources are not destroyed.

[0097] As mentioned above, although this invention was demonstrated based on embodiment, this invention is not limited to the said embodiment.

[0098] The microwave plasma processing device is not limited to performing film forming, etching and ashing processes, but can also perform reduction and other reaction processes on the target gas. Figure 6 In the case of the microwave plasma processing apparatus 100 shown, a medium such as a reducing catalyst is arranged in the sample processing chamber 102 instead of the holding table 107 and the object to be processed 106. In addition, the gas outlet 108 serves as a channel for recovering the reducing gas and other processed gases. The processed gas supplied to each container 103 under reduced pressure is, for example, carbon dioxide gas, which becomes a plasma state through microwaves and is converted into a reduced body, namely carbon monoxide. However, since the processed gas undergoes a reduction reaction due to hydrogen radicals, a gas to which hydrogen is added at a prescribed ratio relative to the carbon dioxide gas is used. That is, the gas G supplied to each container 103 is hydrogen mixed with carbon dioxide gas, and the supply amount of hydrogen is usually 1 to 100 sccm, and the supply amount of carbon dioxide gas is usually 1 to 100 sccm. The supply amount of hydrogen is preferably 1 to 100 times the supply amount of carbon dioxide gas, and more preferably 1 to 10 times the supply amount of carbon dioxide gas. As the reduction catalyst, one or more metal elements from the fourth period onwards of the periodic table, specifically, titanium, vanadium, chromium, iron, cobalt, nickel, copper, zinc, gallium, zirconium, molybdenum, ruthenium, palladium, tungsten, platinum, gadolinium, etc. can be used. During the reduction reaction, the reduction catalyst is maintained at a temperature of, for example, 200° C. or higher and 800° C. or lower, for example, by using a heater (not shown).

[0099] The microwave plasma processing device 100 can cause a reduction reaction to occur without using a reduction catalyst. In this case, the sample processing chamber 102 recovers the carbon monoxide gas discharged from each container 103. The sample processing chamber 102 may be provided with a separation membrane that separates the carbon monoxide gas from the oxygen produced at the same time. As such a separation membrane, for example, a porous material can be used (see https: / / www.jst.go.jp / pr / announce / 20131213-2 / index.html). Each container 103 that produces a reduction reaction has an inner diameter of, for example, 10 to 200 mm, preferably an inner diameter of 20 to 100 mm, and more preferably an inner diameter of 30 to 80 mm. The ratio L1 / R1 of the axial length L1 of each container 103 to the inner diameter R1 is 0.5 or more, preferably 2 or more. The pressure in each container 103 is usually 0.01 to 1000 Pa, preferably 0.1 to 200 Pa, and more preferably 1 to 50 Pa.

[0100] The microwave plasma processing apparatus may be used as an apparatus for performing activation or other pre-treatment on the surface of a bonding target in order to process the surface of the bonding target when bonding different materials.

[0101] It should be noted that this application claims priority based on Japanese application with application number 2022-119771, filed on July 27, 2022, and all disclosed contents are cited herein.

Claims

1. A microwave plasma generating device, comprising a plurality of microwave plasma generators, each microwave plasma generator comprising: a cylindrical container formed of a dielectric body; a cylindrical chamber arranged outside the cylindrical container so as to cover the cylindrical container; a gas supply port, which is disposed at one end of the cylindrical container and supplies gas into the cylindrical container; A microwave introduction port, which is arranged on the side of the cylindrical chamber; Each microwave plasma generator generates plasma along the inner surface of the cylindrical container. The microwave plasma generating device is characterized in that: A discharge portion is provided, the discharge portion being connected to the other end of the cylindrical container and discharging a reactive gas generated by a reaction between the gas and the plasma, The discharge portion includes a conductive tube inside, and the conductive tube has a reduced diameter than the other end of the cylindrical container.

2. The microwave plasma generating device according to claim 1, wherein: The conductive tube of the discharge portion is formed by a metal tube connected to the other end of the cylindrical container and satisfies any of the following conditions: (1) The inner diameter of the metal tube is 0.1 mm or more and less than half the wavelength of the microwave used, and the ratio L2 / R2 of the axial length L2 of the metal tube to the inner diameter R2 is 0.5 or more; (2) the inner diameter of the metal tube is less than the inner diameter of the cylindrical container, and the ratio L2 / R2 of the axial length L2 of the metal tube to the inner diameter R2 is greater than 0.5; or (3) The inner diameter of the metal tube is 0.1 mm or more and 65% or less of the inner diameter of the cylindrical container.

3. The microwave plasma generating device according to claim 1, wherein: The metal pipe is connected to the other end of the cylindrical container via a connecting member.

4. The microwave plasma generating device according to claim 3, wherein: The connecting member covers the other end of the cylindrical container and has a hole at the center thereof to which the metal pipe is connected.

5. The microwave plasma generating device according to claim 4, wherein: The connecting member has a disc shape or a cone shape.

6. The microwave plasma generating device according to claim 1, wherein: The cylindrical container has an inner diameter of 10 mm or more and 300 mm or less and a thickness of 1 mm or more and 100 mm or less.

7. The microwave plasma generating device according to claim 1, wherein: The metal tube is made of at least one selected from stainless steel, aluminum and aluminum alloy.

8. The microwave plasma generating device according to claim 1, wherein: The cylindrical chamber is at least one selected from stainless steel, aluminum, and aluminum alloy.

9. A microwave plasma processing device, comprising: The microwave plasma generating device according to claim 1; A sample processing chamber is connected to the microwave plasma generator and is supplied with the reactive gas generated in the microwave plasma generator.

10. The microwave plasma processing device according to claim 9, wherein: The sample processing chamber comprises: a holding table for holding the object to be processed arranged in such a manner that the reactive gas can be irradiated thereon; A gas exhaust port exhausts the supplied gas and the processed reactive gas.

11. A microwave plasma processing method, using a microwave plasma processing device to process a workpiece, the microwave plasma processing device comprising: a microwave plasma generating device, which has a plurality of microwave plasma generators; a sample processing chamber, which is connected to the microwave plasma generating device and is configured in a manner to be supplied with a reactive gas generated in the microwave plasma generating device, The microwave plasma treatment method is characterized in that The microwave plasma generator comprises a cylindrical container formed of a dielectric, a cylindrical chamber arranged to cover the cylindrical container from the outside, a gas supply port provided at one end of the cylindrical container and supplying gas into the cylindrical container, and a microwave introduction port provided on the side of the cylindrical chamber. The sample processing chamber has a holding table and a gas exhaust port. The discharge portion connected to the other end of the cylindrical container and discharging the reactive gas generated by the reaction between the gas and the plasma includes a conductive tube inside, and the conductive tube has a reduced diameter compared to the other end of the cylindrical container. Gas is supplied from the gas supply port, and microwaves are introduced from the microwave introduction port to generate plasma inside the cylindrical container. The reactive gas generated by the reaction between the gas and the plasma is supplied to the sample processing chamber connected to the cylindrical container, and the supplied gas and the processed reactive gas are discharged from the gas exhaust port provided in the sample processing chamber, and at the same time, the processed object held on the holding table in the sample processing chamber is irradiated with the reactive gas, thereby processing the processed object.

12. The microwave plasma processing method according to claim 11, wherein: The pressure in the cylindrical container, or in the cylindrical container and the cylindrical chamber is maintained at 10 Torr or less.

13. The microwave plasma processing method according to claim 12, wherein: The pressure in the cylindrical container or in the cylindrical container and the cylindrical chamber is maintained at 1 mTorr or more and 10 Torr or less.

14. The microwave plasma processing method according to claim 11, wherein: The flow rate of the gas supplied into the cylindrical container is greater than or equal to 0.01 sccm and less than or equal to 1000 sccm.

15. The microwave plasma processing method according to claim 14, wherein: The flow rate of the gas supplied into the cylindrical container is greater than or equal to 0.01 sccm and less than or equal to 500 sccm.

16. The microwave plasma processing method according to claim 11, wherein: The output power of the supplied microwaves is 10 W or more and 10000 W or less.

17. A microwave plasma treatment method, comprising treating an object to be treated using a microwave plasma treatment device, wherein the microwave plasma treatment device comprises a microwave plasma generator, wherein the microwave plasma generator comprises a plurality of microwave plasma generators, The microwave plasma treatment method is characterized in that The microwave plasma generator comprises a cylindrical container formed of a dielectric, a cylindrical chamber arranged to cover the cylindrical container from the outside, a gas supply port provided at one end of the cylindrical container and supplying gas into the cylindrical container, and a microwave introduction port provided on the side of the cylindrical chamber. The discharge portion connected to the other end of the cylindrical container and discharging the reactive gas generated by the reaction between the gas and the plasma includes a conductive tube inside, and the conductive tube has a reduced diameter compared to the other end of the cylindrical container. Gas is supplied from the gas supply port, and microwaves are introduced from the microwave introduction port to generate plasma inside the cylindrical container. The reactive gas is exhausted from the cylindrical container.

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