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

Abstract

The purpose of the present invention is to provide: a microwave plasma generation device that can increase the amount of microwaves transmitted into a discharge space inside a cylindrical container and improve the energy utilization efficiency of the microwaves; and a microwave plasma processing device that uses the microwave plasma generation device. A microwave plasma generation device according to the present invention comprises a cylindrical container that comprises a dielectric, a cylindrical chamber that is provided outside the cylindrical container so as to cover the cylindrical container, a gas supply port that supplies a gas into the cylindrical container, and a microwave introduction port that is provided in the side of the cylindrical chamber. The microwave plasma generation device is for generating plasma along the inside surface of the cylindrical container and is characterized in that the space between the cylindrical container and the cylindrical chamber is filled with a dielectric material.

Description

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

[0001] The present invention relates to a microwave plasma generating device that generates plasma using microwaves, a microwave plasma processing apparatus using the same, and a method for performing microwave plasma processing using the microwave plasma processing apparatus or the like.

[0002] In semiconductor manufacturing processes, plasma processing is often used for etching semiconductor substrates, film deposition, etc. As a plasma processing apparatus for performing such plasma processing, microwave plasma processing apparatuses that can uniformly generate high-density, low-electron-temperature plasma have attracted attention.

[0003] A microwave plasma processing apparatus has a microwave excitation type plasma source that excites plasma using microwaves with a wavelength of several hundred MHz to several tens of GHz, and because the plasma potential is lower than that of a high-frequency plasma source, it is widely used for damage-free resist ashing, anisotropic etching with an applied bias voltage, and the like.

[0004] Patent Document 1 (Japanese Patent Laid-Open No. 2003-38951) discloses a plasma generating device that includes a vacuum chamber, a waveguide that guides microwaves, a cylindrical microwave introduction part made of a dielectric that introduces the microwaves guided by the waveguide into the vacuum chamber, and a discharge space surrounded by the microwave introduction part, wherein the waveguide is arranged to surround the periphery of the cylindrical microwave introduction part, and that is capable of generating plasma of a reactive gas supplied into the discharge space by microwaves introduced into the discharge space via the microwave introduction part.

[0005] However, in the case of the plasma generator having the configuration described in Patent Document 1, there is a problem in that the transmission of microwaves into the discharge space is reduced due to the cylindrical microwave introduction section made of a dielectric material that is arranged between the microwave waveguide and the plasma generation region in the discharge space, and therefore a configuration that can utilize microwave energy more efficiently is desired.

[0006] Patent Document 2 (JP 2008-177131 A) discloses a plasma generator that includes an inlet waveguide for introducing microwaves, a dielectric (discharge tube) that separates a reduced-pressure space from an atmospheric-pressure space, and a plasma expansion member having a dielectric constant lower than that of the dielectric, and that introduces microwaves into the dielectric from the atmospheric-pressure space side to generate plasma on the reduced-pressure space side. Patent Document 2 describes that by providing a member (plasma expansion member) with a lower dielectric constant than the discharge tube, the propagation range of the microwaves can be expanded and the plasma generation range can also be expanded, thereby suppressing concentrated plasma generation.

[0007] However, in the plasma generator described in Patent Document 2, a microwave passage having a passage width W [a value greater than half the wavelength (λ / 2) of the microwave and smaller than one wavelength (λ)] is provided between the plasma extension member and the introduction waveguide, and a gap is provided between the inner peripheral surface of the plasma extension member and the outer peripheral surface of the discharge tube. This causes problems such as reduced microwave transmission from this microwave passage (air) to the plasma extension member and reduced microwave transmission from the gap to the discharge tube, and leaves room for improvement in terms of energy efficiency.

[0008] JP 2003-38951 A JP 2008-177131 A

[0009] Therefore, an object of the present invention is to provide a microwave plasma generator that increases the amount of microwaves transmitted into a discharge space inside a cylindrical container and improves the efficiency of microwave energy utilization, as well as a microwave plasma processing apparatus using the microwave plasma generator and a method for performing microwave plasma processing using the microwave plasma processing apparatus.

[0010] In view of the above object, the inventors discovered that by filling the microwave propagation region on the outer periphery of a cylindrical container made of a dielectric with a dielectric material having a dielectric constant different from that of the cylindrical container, the amount of microwave transmission into the discharge space inside the cylindrical container can be increased, and thus arrived at the present invention.

[0011] That is, the microwave plasma generator of the present invention comprises a cylindrical container made of a dielectric, a cylindrical chamber arranged on the outside of the cylindrical container so as to cover the cylindrical container, a gas supply port for supplying gas into the cylindrical container, and a microwave inlet port provided on the side of the cylindrical chamber, and is a microwave plasma generator for generating plasma along the inner surface of the cylindrical container, and between the cylindrical container and the cylindrical chamber, a dielectric material having a dielectric constant equal to or higher than the dielectric constant of the cylindrical container is arranged so as to cover the cylindrical container.

[0012] The microwave plasma generator of the present invention can increase the amount of microwaves transmitted into the discharge space inside the cylindrical container, thereby improving the efficiency of microwave energy utilization. Furthermore, by arranging a dielectric material with a higher dielectric constant outside the cylindrical container, the microwave wavelength can be effectively shortened, allowing the microwave plasma generator to be made smaller. Therefore, the microwave plasma generator is particularly suitable for small-sized microwave plasma processing apparatuses and processing methods using the same.

[0013] The microwave plasma processing method of the present invention is a method for processing the workpiece using the microwave plasma processing apparatus, and is characterized in that gas is supplied from the gas supply port provided in the cylindrical container of the microwave plasma generating device, microwaves are introduced from the microwave inlet port provided on the side of the cylindrical chamber, plasma is generated inside the cylindrical container, the plasma is supplied to the sample processing chamber connected to the cylindrical container, and gas containing the supplied gas and the plasma after processing is exhausted from the gas exhaust port provided in the sample processing chamber, thereby irradiating the plasma to the workpiece held on the holding table in the sample processing chamber and processing the workpiece.

[0014] The microwave plasma processing method of the present invention is a method for processing a workpiece using a microwave plasma generator including a cylindrical container made of a dielectric and a cylindrical chamber arranged outside the cylindrical container so as to cover the cylindrical container, wherein the microwave plasma generator includes a gas supply port for supplying gas into the cylindrical container and a microwave inlet provided on the side of the cylindrical chamber, and a dielectric material having a dielectric constant equal to or higher than that of the cylindrical container is arranged between the cylindrical container and the cylindrical chamber so as to cover the cylindrical container, and gas is supplied from the gas supply port and microwaves are introduced from the microwave inlet provided on the side of the cylindrical chamber to generate plasma inside the cylindrical container and release a reaction gas produced by a reaction between the gas and the plasma from the cylindrical container.

[0015] Fig. 1a is a schematic cross-sectional view showing an example of a microwave plasma processing apparatus of the present invention. Fig. 1b is a cross-sectional view taken along the line A-A in Fig. 1a. Fig. 2a is a schematic cross-sectional view showing an example of a configuration using two types of dielectric materials. Fig. 2b is a schematic cross-sectional view showing another example of a configuration using two types of dielectric materials. Fig. 2c is a schematic cross-sectional view showing yet another example of a configuration using two types of dielectric materials.

[0016] [1] Microwave Plasma Processing Apparatus FIGS. 1a and 1b show an example of a microwave plasma generating apparatus 100 of the present invention. The microwave plasma processing apparatus 100 of the present invention is a microwave plasma processing apparatus 100 comprising a microwave plasma generator 101 that generates plasma by microwaves, and a sample processing chamber 102 that is connected to the microwave plasma generator 101 and arranged so as to be supplied with the plasma generated by the microwave plasma generator 101, wherein the microwave plasma generator 101 comprises a cylindrical container 103 made of a dielectric, a cylindrical chamber 109 that is arranged on the outside of the cylindrical container 103 so as to cover the cylindrical container, a gas supply port 104 that supplies gas into the cylindrical container 103, and a microwave inlet 105 that is provided on the side of the cylindrical chamber 109, and is a microwave plasma generating apparatus 101 for generating plasma along the inner surface of the cylindrical container 103, and is characterized in that a layer of dielectric material 110 that covers the cylindrical chamber 109 is arranged between the cylindrical container 103 and the cylindrical chamber 109. The dielectric material 110 has a dielectric constant different from that of the cylindrical container 103 and has a dielectric constant portion having a dielectric constant equal to or higher than that of the cylindrical container 103. In other words, the space between the cylindrical container 103 and the cylindrical chamber 109 may be entirely filled with a dielectric material having the same or higher dielectric constant, or a dielectric material having the same or higher dielectric constant may be arranged cylindrically on the outside of the cylindrical container 103, and a dielectric material portion having a dielectric constant relatively lower than that of the cylindrical container 103 may be provided on the outside or inside of the cylindrical container 103.

[0017] (1) Microwave Plasma Generator The microwave plasma generator 101 of the present invention is a device for generating plasma using microwaves, and when microwaves M are introduced from a microwave inlet 105 provided on the side of a cylindrical chamber 109 while a gas G (e.g., hydrogen gas) is supplied from a gas supply port 104 into a cylindrical container 103 maintained under reduced pressure, the microwaves generate standing waves using the surface of the cylindrical container 103 as a transmission path, and plasma of the gas G is generated inside the cylindrical container 103 by the microwaves that have transmitted through the cylindrical container 103. At this time, by filling the gap between the cylindrical container 103 and the cylindrical chamber 109 with a dielectric material 110 or by arranging the dielectric material 110 so as to cover the cylindrical container 103, microwave reflection at the interface between the cylindrical container 103 and air is suppressed, and microwaves are sufficiently transmitted inside the cylindrical container 103, improving plasma generation efficiency and, as a result, increasing processing efficiency.

[0018] When a material having a dielectric constant equal to or higher than that of the cylindrical container 103 is used as the dielectric material 110, the wavelength decreases due to an increase in the refractive index, thereby enabling the device dimensions to be reduced, thereby further improving the processing efficiency. Furthermore, when a material having a dielectric constant equal to or higher than that of the cylindrical container 103 is used as the dielectric material 110, if there is a gap between the cylindrical container 103 and the dielectric material 110, or if the dielectric constant of the dielectric material 110 is higher than that of the cylindrical container 103, components of the microwaves M incident on the surface of the cylindrical container 103 from the outside of the cylindrical container 103 that satisfy the total reflection condition are reflected. The microwaves M reflected on the surface of the cylindrical container 103 propagate through the gap space between the cylindrical container 103 and the chamber 109, gradually pass through the surface of the cylindrical container 103, and enter the interior of the cylindrical container 103. As a result, the microwaves M are uniformly supplied from the periphery into the cylindrical container 103, and plasma is efficiently generated within the cylindrical container 103. The dielectric constant of the dielectric material 110 is preferably more than 1 time, and more preferably 1.1 to 10 times, the dielectric constant of the cylindrical container 103. A dielectric material having the same or higher dielectric constant may be used only in part. This provides the effects of reducing the size of the device and efficiently supplying microwaves.

[0019] The dielectric material 110 disposed in the gap between the cylindrical container 103 and the cylindrical chamber 109 may be composed of one type of dielectric material, or two or more types of dielectric materials. For example, when composed of two types of dielectric materials, the two types of dielectric materials 110a, 110b may be divided and arranged in layers in the radial direction (i.e., concentrically with the cylindrical container) as shown in FIG. 2a, or divided and arranged alternately in the circumferential direction as shown in FIG. 2b, or may be arranged in a mosaic pattern by combining divisions in the radial direction and divisions in the circumferential direction as shown in FIG. 2c. The radial width and layer width when dividing each dielectric material may be selected appropriately. The same applies to a case where three or more types of dielectric materials are used.

[0020] The dielectric material 110 filling the gap between the cylindrical container 103 and the cylindrical chamber 109 may be configured by arranging materials with different dielectric constants in the axial direction. For example, a dielectric material with an axial length (height) of 90 mm (millimeters) may have a dielectric constant of 3 for a 30 mm length at one end (upper portion) and a 30 mm length at the other end (lower portion), and a dielectric constant of 6 for a 30 mm length in the central portion. With such a configuration, plasma is concentrated in the central portion, and a high effect can be expected.

[0021] When two or more types of dielectric materials (specifically, dielectric materials 110a and 110b) are arranged in layers in the radial direction (i.e., concentrically with the cylindrical container), that is, when the dielectric material 110 is made of two or more layers of dielectric material provided so as to cover the cylindrical container, it is preferable that the dielectric material 110a closest to the cylindrical container 103 has a dielectric constant equal to or higher than the dielectric constant of the cylindrical container 103. In this case, the dielectric constant of the dielectric material 110b farther from the cylindrical container 103 may be higher or lower than that of the cylindrical container 103, and may be higher or lower than that of the dielectric material 110a closest to the cylindrical container 103. It is preferable that the volume-averaged dielectric constant of the two dielectric materials is higher than 1.

[0022] The cylindrical container 103 is preferably made of a material that has excellent corrosion resistance against plasma, such as an amorphous material made of quartz (relative dielectric constant: 3.9), alumina (relative dielectric constant: 9.0), boron nitride (relative dielectric constant: 4), or aluminum nitride (relative dielectric constant: 8.5).

[0023] Examples of materials that can be used as the dielectric material 110 include mica (6-8), acrylic resin (2.7-4.5), urethane (6.5-7.1), glass (3.7-10.0), glass-epoxy laminate (4.5-5.2), silicone resin (3.5-5), styrene-butadiene rubber (3.0-7.0), quartz glass (3.5-4.0), nylon (3.5-5.0), neoprene (6.0-9.0), fluororesin (4.0-8.0), unsaturated polyester resin (2.8-5.2), polyester resin (2.8-8.1), phenolic resin (3.0-12.0), polyurethane (5.0-5.3), polymethyl acrylate (4.0), melamine resin (4.7-10.2), and wood (2.0-6.0). The numbers in parentheses after each dielectric material indicate the relative permittivity. The glass mentioned above refers to various inorganic glasses including silicate glass, borosilicate glass, quartz glass, etc. When the cylindrical container 103 is made of quartz glass, ceramics such as alumina, boron nitride, and aluminum nitride can be used as the dielectric material 110. The state of the dielectric material 110 is not particularly limited, and may be, for example, a solid, liquid, or bead form.

[0024] The dielectric material 110 is preferably solid. When the dielectric material 110 is solid, it is possible to prevent the dielectric material 110 from leaking out from the space between the cylindrical container 103 and the cylindrical chamber 109. Furthermore, when the dielectric material 110 is solid, even when the dielectric material 110 is heated by the microwaves M, convection does not occur, and therefore the dielectric material 110 is maintained in a stable state.

[0025] In order to ensure that the dielectric constant of the dielectric material 110 is sufficiently higher than that of the cylindrical container 103, if the cylindrical container 103 is formed of quartz glass, it is desirable to use mica, glass, fluorine, alumina, boron nitride, or aluminum nitride.

[0026] In the case where two types of dielectric material 110 are arranged in two layers in the gap between cylindrical container 103 and cylindrical chamber 109 and are arranged to cover cylindrical container 103, if cylindrical container 103 is formed of, for example, quartz glass, inner dielectric material 110a may be a cylindrical layer made of, for example, quartz glass, and outer dielectric material 110b may be a cylindrical layer made of, for example, mica. In this case, the dielectric constant of inner dielectric material 110a is equal to that of cylindrical container 103, and the dielectric constant of outer dielectric material 110b is higher than that of cylindrical container 103, based on the dielectric constant of cylindrical container 103. Generalizing this, it can be said that dielectric material 110b, having a dielectric constant equal to or higher than that of cylindrical container 103, is arranged to cover cylindrical container 103. That is, as long as the dielectric material 110b having a dielectric constant equal to or higher than that of the cylindrical container 103 is arranged so as to cover the cylindrical container 103, a layer having the same dielectric constant as that of the cylindrical container 103 (a layer made of the same material as the cylindrical container 103) or a layer having a dielectric constant lower than that of the cylindrical container 103 (for example, an air layer) may be arranged as the layer of the inner dielectric material 110a between the outer layer of the dielectric material 110b and the cylindrical container 103. Furthermore, a layer of a dielectric material having a dielectric constant equal to or lower than that of the cylindrical container 103 may be arranged outside the dielectric material 110b having a dielectric constant equal to or higher than that of the cylindrical container 103 (in this case, the dielectric material 110a may be omitted).

[0027] The dielectric material 110 is preferably disposed in close contact with the cylindrical container 103 and the cylindrical chamber 109 so that no gaps are formed between the cylindrical container 103 and the cylindrical chamber 109. If gaps are formed between the cylindrical container 103 and the cylindrical chamber 109, an interface between the air and the dielectric material 110 is formed, causing microwave reflection at the interface and tending to reduce the microwaves transmitted to the inside of the cylindrical container 103.

[0028] The cylindrical container 103 preferably has an inner diameter of 10 to 300 mm and a thickness of 5 to 100 mm, more preferably an inner diameter of 20 to 100 mm and a thickness of 10 to 50 mm, and most preferably an inner diameter of 30 to 80 mm and a thickness of 15 to 30 mm. The present invention is suitable for such a relatively small microwave plasma generator.

[0029] The microwave inlet 105 of the microwave plasma generator 101 is preferably provided with a microwave anti-reflection structure 111 at the portion connecting to the cylindrical chamber 109 to prevent microwaves from being reflected when irradiated almost perpendicularly onto the dielectric material 110 and the cylindrical container 103, thereby reducing the utilization efficiency of the microwaves. The anti-reflection structure 111 may be, for example, a structure having a number of nano-level minute protrusions arranged at regular intervals, i.e., a moth-eye structure. Alternatively, a layer of a low-dielectric-constant material may be provided.

[0030] (2) Sample Processing Chamber The sample processing chamber 102 is connected to the microwave plasma generator 101 and is arranged so that the plasma generated by the microwave plasma generator 101 is supplied to the sample processing chamber 102. The sample processing chamber 102 includes a holder 107 for holding the workpiece 106 so that the workpiece 106 is irradiated with the plasma generated by the microwave plasma generator 101, and a gas exhaust port 108 for exhausting the supplied gas and gas containing the plasma after processing. The holder 107 is rotatable about a predetermined rotation axis R, and it is preferable that the rotation axis R and the central axis C of the cylindrical container 103 are not on the same line. Alternatively, the rotation axis R and the central axis C of the cylindrical container 103 may be arranged so as to be inclined at a predetermined angle. The holder 107 is preferably equipped with a temperature control function.

[0031] The location of the gas exhaust port 108 is not particularly limited, but it is preferably downstream of the holding table 107, that is, behind the holding table 107 as viewed from the microwave plasma generator 101. In particular, it is preferably provided on the side of the holding table 107 opposite to the side on which the workpiece 106 is placed.

[0032] [2] Microwave Plasma Processing Method The microwave plasma processing method of the present invention is performed using a microwave plasma processing apparatus 100 (e.g., the apparatus shown in FIGS. 1a and 1b ) including the microwave plasma generator 101 described above 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, microwaves M are introduced from a microwave inlet 105 provided on a side of a cylindrical chamber 109, plasma is generated inside the cylindrical container 103, the plasma is supplied to the sample processing chamber 102 connected to the cylindrical container 103, and a gas containing the supplied gas G and the plasma after processing is exhausted from a gas exhaust port 108 provided in the sample processing chamber 102, thereby irradiating the workpiece 106 held on a holding table 107 in the sample processing chamber 102 with a plasma-containing gas (also referred to as a “reactive gas”), thereby processing the workpiece 106.

[0033] The microwave plasma treatment is carried out by supplying a gas G (e.g., hydrogen gas) at a flow rate of 0.1 to 10 sccm (standard cubic centimeter per minute) from a gas supply port 104 into a cylindrical container 103 maintained at a pressure of 1 Torr or less, while supplying a microwave with an output of 100 to 2000 watts (W) (e.g., 2450 MHz and 800 watts per square centimeter (W / cm)) from a microwave inlet 105. ２ )) microwaves M are introduced into the cylindrical container 103, and a cylindrical reactive gas G is generated inside the cylindrical container 103 by the microwaves in a standing wave state. Ａ The object to be treated 106 was kept at 0 to 400° C., and the support table 107 was rotated while the density of the object to be treated was 5×10 １４ pieces / cm ３ Reactive gas G containing the above radicals Ａ This results in the product of the irradiation time and density of radicals reaching 25×10 on the workpiece 106. １４ Minutes / pieces / cm ３ The reactive gas G ＡThe potential difference between the reactive gas G and the surface of the workpiece 106 is preferably 10 V or less. Ａ The excess gas G is exhausted from a gas exhaust port 108. The radical irradiation density can be determined by a known method (T. Arai et al. (2016) "Selective Heating of Transition Metal Using Hydrogen 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).

[0034] In the above, the microwave M introduced from the microwave inlet 105 may be supplied continuously or may be supplied in a pulsed manner.

[0035] As the gas G, hydrogen gas is used from the viewpoint of generating hydrogen radicals, but gases other than hydrogen gas, such as nitrogen, oxygen, carbon dioxide, ammonia, and rare gases (helium, neon, argon, etc.), can also be used depending on the purpose of the treatment. ２ When forming a film, hydrogen gas, oxygen gas, etc. are used to generate radicals of hydrogen, oxygen, etc., and when etching Si, for example, CF ４ , C.F. ６ Fluorine radicals are generated using fluorine gas. When ashing a resist, oxygen gas radicals are generated.

[0036] The pressure inside the cylindrical container 103, or inside the cylindrical container 103 and the cylindrical chamber 109, is preferably kept at 10 Torr or less, more preferably at 1 mTorr to 10 Torr, and most preferably at 10 mTorr to 1 Torr.

[0037] 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 will not increase, and if it is more than 100 sccm, the exhaust will not keep up and the pressure will become unstable.

[0038] The gas pumping speed is preferably 1 to 10,000 liters / minute (L / min), more preferably 10 to 2,000 L / min, and even more preferably 50 to 1,000 L / min. If the gas pumping speed is less than 1 L / min, it takes a long time to pump the gas, and if it is more than 10,000 L / min, it is too costly.

[0039] Microwave output: 10 to 10,000 W / cm ２ It is preferable to set the range to 100 to 1000 W / cm ２ More preferably, it is 200 to 700 W / cm ２ It is most preferable to set the irradiance to 10 W / cm. ２ Smaller values ​​result in less reactive gas generation, and 10,000 W / cm ２ Anything larger would be too costly.

[0040] The treatment time is preferably 0.001 to 100 minutes, more preferably 0.01 to 50 minutes, and even more preferably 0.05 to 20 minutes. If the treatment time is shorter than 0.001 minute, the effect is reduced, and if it is longer than 100 minutes, productivity is reduced.

[0041] The rotation speed of the support table 107 is preferably 0.1 to 10,000 rpm, more preferably 1 to 1,000 rpm, and even more preferably 10 to 200 rpm. If the rotation speed is slower than 0.1 rpm, unevenness will occur, and if it is faster than 10,000 rpm, mechanical durability will decrease.

[0042] The present invention will be described in more detail by the following examples, but the present invention is not limited thereto.

[0043] Comparative Example 1: A model of a microwave plasma generator was created, which consisted of a cylindrical vessel made of quartz glass (dielectric constant: 3.9) with an inner diameter of 80 mm, an outer diameter of 100 mm, and an axial length of 100 mm, and a cylindrical chamber (made of stainless steel) with an inner diameter of 180 mm, an outer diameter of 200 mm, and an axial length of 100 mm, both of which were concentrically arranged and covered with stainless steel metal plates at the top and bottom. In this model, the steady state of the electromagnetic waves was calculated using OpenFDTD (manufactured by EEM Corporation), and the maximum plasma intensity inside the cylindrical vessel was determined.

[0044] [Examples 1 to 3] As shown in Table 1, models of Examples 1 to 3 were prepared by filling the space between the cylindrical container and the cylindrical chamber with mica (relative dielectric constant: 6 to 8), quartz glass, and polyethylene (relative dielectric constant: 2.3 to 2.4), respectively, and the maximum plasma intensity inside the cylindrical container was determined in the same manner as in Comparative Example 1. The dielectric material faced the outer peripheral surface of the cylindrical container via a thin layer of air. Polyethylene has a dielectric constant substantially equivalent to that of quartz glass, but is inferior to quartz glass.

[0045] [Comparative Examples 2 and 3] As shown in Table 1, models of Comparative Examples 2 and 3 were prepared in which quartz glass and polyethylene were placed as dielectric materials on the outer periphery of a cylindrical container (within a range of 100 to 120 mm from the center), with air filling the spaces between these dielectric materials and the cylindrical chamber, and the maximum plasma intensity inside the cylindrical container was determined in the same manner as in Comparative Example 1. Comparative Example 2 is an example, but no significant effect was obtained.

[0046] Example 4 As shown in Table 1, a model of Example 4 was prepared in which mica was arranged as a dielectric material on the outer periphery of a cylindrical container (within a range of 100 to 120 mm from the center) and quartz glass was arranged as a dielectric material between the mica and the cylindrical chamber. The maximum plasma intensity inside the cylindrical container was determined in the same manner as in Comparative Example 1.

[0047] Example 5 As shown in Table 1, a model of Example 5 was produced in which mica was arranged as a dielectric material on the outer periphery of a cylindrical container (within a range of 100 to 120 mm from the center), quartz glass was arranged as a dielectric material on the outer periphery of that (within a range of 120 to 140 mm from the center), mica was arranged as a dielectric material on the outer periphery of that (within a range of 140 to 160 mm from the center), and quartz glass was arranged as a dielectric material on the outer periphery of that (within a range of 160 to 180 mm from the center). The maximum plasma intensity inside the cylindrical container was determined in the same manner as in Comparative Example 1.

[0048] Table 1 shows the maximum plasma intensity of each sample as a relative value, with the maximum plasma intensity of Comparative Example 1 being set to 1.0. These results show that the microwave plasma generator of the present invention, which is configured by disposing a dielectric material between the cylindrical container and the cylindrical chamber, can obtain a higher plasma intensity than one without a dielectric material.

[0049] Note (1): Relative value with the maximum plasma intensity value of Comparative Example 1 set to 1.0

[0050] Although the present invention has been described above based on the embodiments, the present invention is not limited to the above embodiments.

[0051] Microwave plasma processing apparatuses are not limited to those performing film formation, etching, and ashing processes, but may also perform reduction or other reaction processes on target gases. In the microwave plasma processing apparatus 100 shown in FIG. 1a, a medium, such as a reduction catalyst, is placed in the sample processing chamber 102 instead of the support stage 107 and the workpiece 106. The gas outlet 108 serves as a port for releasing reduced gases and other processed or reactive gases and for recovering the processed gases. The processed gas supplied to each container 103 under reduced pressure is, for example, carbon dioxide gas, which is converted to carbon monoxide gas, a reduced gas. However, since the processed gas undergoes a reduction reaction with hydrogen radicals, a predetermined ratio of hydrogen gas to carbon dioxide gas is used. In other words, the gas G supplied to each container 103 is a mixture of hydrogen gas and carbon dioxide gas, with the hydrogen gas supply rate typically being 1 to 100 sccm, and the carbon dioxide gas supply rate typically being 1 to 100 sccm. The amount of hydrogen gas supplied is preferably 1 to 100 times the amount of carbon dioxide gas supplied, and more preferably 1 to 10 times the amount of carbon dioxide gas supplied. The reduction catalyst may contain one or more metal elements from the fourth period of the periodic table or later, and specific examples include titanium, vanadium, chromium, iron, cobalt, nickel, copper, zinc, gallium, zirconium, molybdenum, ruthenium, palladium, tantalum, tungsten, platinum, and gadolinium. The reduction catalyst is maintained at a temperature of, for example, 200°C or higher and 800°C or lower by a heater (not shown) during the reduction reaction.

[0052] The microwave plasma processing apparatus 100 may also be configured to cause a reduction reaction without using a reduction catalyst. In this case, the sample processing chamber 102 collects carbon monoxide gas discharged from each container 103 in a single unit. The sample processing chamber 102 may be provided with a separation membrane filter that separates carbon monoxide gas from oxygen simultaneously generated. Such a separation membrane may be made of, for example, a porous material (see https: / / www.jst.go.jp / pr / announce / 20131213-2 / index.html). Each container 103 in which a reduction reaction occurs has an inner diameter of, for example, 10 to 200 mm, preferably 20 to 100 mm, and more preferably 30 to 80 mm. The ratio L1 / R1 of the axial length L1 to the inner diameter R1 of each container 103 is 0.5 or greater, preferably 2 or greater. The pressure inside each vessel 103 is usually set to 0.01 to 1000 Pa, preferably 0.1 to 200 Pa, and more preferably 1 to 50 Pa.

[0053] The microwave plasma processing apparatus can be used as an apparatus for performing activation or other pretreatment on the surfaces of the objects to be bonded in order to perform surface treatment on the objects to be bonded when bonding dissimilar materials.

Claims

1. A microwave plasma generating device for generating plasma along an inner surface of the cylindrical container, comprising: a cylindrical container made of a dielectric material; a cylindrical chamber arranged on the outside of the cylindrical container so as to cover the cylindrical container; a gas supply port for supplying gas into the cylindrical container; and a microwave inlet port provided on the side of the cylindrical chamber, wherein a dielectric material having a dielectric constant equal to or greater than the dielectric constant of the cylindrical container is arranged between the cylindrical container and the cylindrical chamber so as to cover the cylindrical container.

2. A microwave plasma generating apparatus as described in claim 1, wherein the dielectric material is made of two or more layers of dielectric material arranged to cover the cylindrical container, and the dielectric material furthest from the cylindrical container has a dielectric constant equal to or greater than the dielectric constant of the cylindrical container.

3. A microwave plasma generating apparatus as claimed in claim 2, wherein the dielectric material closest to said cylindrical container has a dielectric constant equal to or greater than the dielectric constant of said cylindrical container.

4. A microwave plasma generating device according to claim 1, characterized in that the microwave inlet is provided with a microwave anti-reflection structure.

5. The microwave plasma generating device according to claim 1, wherein the cylindrical container has an inner diameter of 10 to 300 mm and a thickness of 5 to 100 mm.

6. A microwave plasma processing apparatus comprising: the microwave plasma generating device according to claim 1; and a sample processing chamber connected to said microwave plasma generating device and arranged so that the plasma generated by said microwave plasma generating device is supplied thereto.

7. A microwave plasma processing apparatus as described in claim 6, characterized in that the sample processing chamber is provided with a holding stage for holding the workpiece so that the plasma can be irradiated onto the workpiece, and a gas exhaust port for exhausting the supplied gas and gas containing the plasma after processing.

8. A method for processing an object to be processed using a microwave plasma processing apparatus including a microwave plasma generating apparatus having a cylindrical container made of a dielectric material and a cylindrical chamber arranged on the outside of the cylindrical container so as to cover the cylindrical container, and a sample processing chamber arranged in connection with the microwave plasma generating apparatus so as to be supplied with plasma generated by the microwave plasma generating apparatus, wherein the microwave plasma generating apparatus has a gas supply port for supplying gas into the cylindrical container and a microwave inlet provided on the side of the cylindrical chamber, the sample processing chamber has a holding table and a gas exhaust port, a dielectric material having a dielectric constant equal to or higher than the dielectric constant of the cylindrical container is arranged between the cylindrical container and the cylindrical chamber so as to cover the cylindrical container, gas is supplied from the gas supply port and microwaves are introduced from the microwave inlet to generate plasma inside the cylindrical container, A microwave plasma processing method in which plasma is supplied to the sample processing chamber connected to the cylindrical container, and the supplied gas and gas containing the plasma after processing are exhausted from the gas exhaust port provided in the sample processing chamber, while the workpiece held on the holding stage in the sample processing chamber is processed by irradiating the plasma to the workpiece.

9. The microwave plasma processing method according to claim 8, wherein the inside of the cylindrical container, or the inside of the cylindrical container and the cylindrical chamber, is maintained at a pressure of 10 Torr or less.

10. The microwave plasma processing method according to claim 8, wherein the flow rate of the gas supplied into the cylindrical container is 0.01 sccm or more and 1000 sccm or less.

11. The microwave plasma processing method according to claim 8, wherein the output of the supplied microwave is 10 to 10,000 W / cm ２ 2. A microwave plasma processing method comprising:

12. A method for treating an object to be treated using a microwave plasma generating device comprising a cylindrical container made of a dielectric material and a cylindrical chamber arranged outside the cylindrical container so as to cover the cylindrical container, wherein the microwave plasma generating device comprises a gas supply port for supplying gas into the cylindrical container and a microwave inlet port provided on the side of the cylindrical chamber, a dielectric material having a dielectric constant equal to or greater than the dielectric constant of the cylindrical container is arranged between the cylindrical container and the cylindrical chamber so as to cover the cylindrical container, a gas is supplied from the gas supply port and microwaves are introduced from the microwave inlet port provided on the side of the cylindrical chamber to generate plasma inside the cylindrical container, and a reaction gas generated by a reaction between the gas and the plasma is released from the cylindrical container.

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