Plasma treatment unit

Abstract

[Problem] To provide a plasma processing device that utilizes microwaves, which can suppress reflected waves and radiate circularly polarized waves with a high axial ratio, and can selectively change the radiation pattern of polarization. [Solution] It has: 2n solid-state microwave sources (2); 2n coaxial waveguide transducers (3) connected to the solid-state microwave sources respectively, converting microwave power from TEM mode to TE10 mode; and a polarization synthesis antenna, which has 2n cutoff waveguides (4) "connected to the circular waveguide every 180° / n on the same plane perpendicular to the axial direction of the circular waveguide (5), the 2n cutoff waveguides are connected to the 2n coaxial waveguide transducers in a one-to-one relationship, in which the microwave power of TE10 mode is blocked and excites a faded field towards the circular waveguide.

Description

Plasma processing apparatus The present invention relates to an ECR (Electron Cyclotron Resonance) plasma processing apparatus using microwaves. In recent years, with the increase in the integration density of semiconductor elements, there has been a demand for improvement in microfabrication, that is, processing accuracy, and it has become more stringent to improve the uniformity of the etching rate and the in-wafer uniformity of the CD value (Critical Dimension) in the processing size. Also, the material to be etched has changed from a single-layer film to a multi-layer film, and in the processing of each multi-layer film, multi-step etching with changing etching conditions is mostly used. In this case, the factors affecting the uniformity of etching, etc., are different for each step, and therefore, it is difficult to obtain the uniformity and axial symmetry of the etching rate at the time point when the etching of each multi-layer film is completed. One of the microfabrication etching techniques in the semiconductor field is dry etching technology, and in particular, dry etching processing using plasma is often used. Plasma excites the molecules or atoms of the processing gas by colliding with electrons and the molecules or atoms of the processing gas, generating ions and free radicals. The plasma processing apparatus achieves anisotropic etching by ions and isotropic etching by free radicals. As a plasma source, there is electron cyclotron resonance ECR (ECR: Electron Cyclotron Resonance). Since ECR can generate high-density plasma, it is used to improve the breakdown voltage of DRAM of semiconductor elements or to form high-capacity capacitors, etc. Fig. 8 shows the configuration of a conventional ECR etching apparatus. The 2.45 GHz microwave emitted from the magnetron 72 propagates in the form of the TE10 mode in the order of the isolator 73, the rectangular waveguide 74, and the three-stub tuner 75, and its propagation form (or mode) is converted into the TE11 mode by the circular-rectangular waveguide converter 76. The circular-rectangular waveguide converter 76 has a diameter of φ90 mm in such a way that the 2.45 GHz microwave can propagate through the basic TE11 mode propagation form. In order to form an axially symmetric radiation of the microwave, a dielectric 1 / 4 wavelength plate 8 made of quartz is used to form a circularly polarized wave, and by rotating the microwave in the TE11 mode propagation form temporally, the electric field distribution of the microwave becomes axially symmetric and is radiated into the cavity 6. In order to propagate the microwave as a circularly polarized wave in the circular waveguide 5, the 1 / 4 wavelength plate 8 is inserted into the circular waveguide 5 at an angle of 45 degrees with respect to the polarization plane of the linearly polarized wave in the TE11 mode. The circularly polarized wave of the microwave incident on the cavity 6 is introduced into the processing chamber 1 through the quartz window 13 and the shower plate 14 located above the processing chamber 1 covered by the "upper electromagnetic coil 9, middle electromagnetic coil 10, and lower electromagnetic coil 11". By the electric field caused by the microwave and the magnetic field formed in the vertical direction relative to it, electron cyclotron motion is carried out. When the frequency of the microwave is 2.45 GHz, since the electrons perpendicular to the magnetic field will have their traveling directions bent due to the Lorentz force, the electrons will gradually perform circular motion. The magnetic flux density B at this time is obtained from the formula: fc = eB / 2πme (e is the electron charge amount of 1.6 × 10 -19 C, me is the electron mass of 9.1 × 10 -31 Kg, fc is 2.45 GHz). When it is set to 875 G, electron cyclotron resonance will occur, and the collision probability between the electrons and the gas molecules in the processing chamber 1 increases. Therefore, even at low pressures, high-density plasma can be generated. The pressure in the processing chamber 1 during etching is reduced to around 1 Pa by the vacuum pump 17, and high-density plasma of 10 11 cm -3 or more can be obtained in this pressure region. Also, since the plasma formation and the independent ion energy can be controlled by applying the RF power supply 16 to the substrate stage 15 to be processed, precise shape control can be performed. Moreover, in order to improve the in-plane uniformity of the substrate w to be processed, a quarter-wave plate 8 is used to input a circularly polarized wave into the processing chamber 1. Since the axial ratio of the circularly polarized wave caused by the quarter-wave plate 8 of the conventional technology does not consider the reflection from the processing chamber 1, when the plasma density in the processing chamber 1 becomes a fixed value, a reflected wave is generated from the processing chamber 1. Since this reflected wave forms an incident wave and a standing wave, it will hinder the rotation of the TE11 mode electric field in the circular waveguide 5 and cause the axial ratio of the circularly polarized wave to be input into the processing chamber 1 to decrease. In addition, the axial ratio is defined as the true circularity of the circularly polarized wave, and 1 represents the highest true circularity. In order to apply uniform plasma processing to the substrate w to be processed, of course, the distribution of plasma characteristics such as the density or temperature of the plasma near the substrate w to be processed is important. From the viewpoint of plasma processing homogenization, the technology of optimizing the plasma distribution is important. A plasma processing device that generates plasma by microwave power has characteristics such as "being able to generate high-density plasma even at low pressures and being able to easily control the plasma distribution by adjusting the static magnetic field distribution in combination with the static magnetic field", and is widely used in the manufacture of semiconductor processing devices, etc. In response to the trend of increasing substrate diameter, in a microwave plasma processing device, the control of plasma distribution is also important. However, microwaves have a short wavelength of about several cm to several tens of cm, and the electric field distribution of microwaves on a semiconductor substrate with dimensions of the same order as the wavelength is likely to change. In order to obtain uniform plasma processing in a wide range, optimizing the microwave distribution becomes a problem. As a conventional technique of "using circularly polarized microwaves in a plasma source that generates plasma using microwaves", for example, there are the following prior art documents. [Prior art documents] [Patent documents] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-192750 [Patent Document 2] Japanese Patent Application Laid-Open No. 2003-188152 [Patent Document 3] Japanese Patent Application Laid-Open No. 2006-339547 [Non-Patent Document] [Non-Patent Document 1] Michael A. Lieberman et. al, “Principles of Plasma Discharges and Materials Processing” John Wiley & Sons, Inc. (2005) [Problems to be Solved by the Present Invention] The etching of the structural pattern of semiconductor elements, especially the shape accuracy and the uniformity of the etching rate of the gate processing that dominates the operating characteristics of semiconductor elements, have become increasingly stringent. In order to solve the above problems, many distribution control techniques of ECR plasma used in dry etching have been proposed. As a conventional technique, in Patent Document 1, a single-mode microwave such as TE10 is inserted from a rectangular waveguide connected to a magnetron, and a wavelength plate of 1 / 4λg (where λg shown here is the wavelength of the electromagnetic wave in a φ90mm circular waveguide at 2.45 GHz) is inserted into the circular waveguide connected to the rectangular waveguide to form a rotating electric field of the TE11 mode in the circular waveguide and radiate it to the processing chamber of the plasma processing device. Thereby, the uniformity of high etching rate is achieved. However, the phase plate of Patent Document 1 has an angle of 45° clockwise with respect to the main polarization plane, and in the etching process, it can only radiate electromagnetic waves that rotate to the right (hereinafter, electromagnetic waves that rotate to the right are referred to as R waves, and electromagnetic waves that rotate to the left are referred to as L waves). As shown in Non-Patent Document 1, since the electromagnetic wave energy of the R wave continuously accelerates electrons wound around the magnetic field lines by the Lorentz force in an environment with a magnetic field B, the energy of the microwave is easily absorbed by the electrons and the electron temperature Te increases. As a result, an electron shielding effect is brought about above the fine patterns such as FinFETs in the semiconductor device structure. Since the ion trajectories of the walls of the fins in the dense and sparse parts of the device patterns incident on the substrate are bent by the negative electric field of the electron shielding effect, cuts of different degrees are formed at the roots of the fins of the FinFET. In Patent Document 2, in order to radiate the rotating TE11 mode electromagnetic wave into the circular waveguide, a cross slot is used at the connection part of the rectangular waveguide and the circular waveguide. However, similar to Patent Document 1, in the plasma processing process, only one of the R wave or the L wave can be radiated and the size and angle of the cross slot are designed according to the determined process conditions. Therefore, when the impedance in the processing chamber changes, the axial ratio of the circularly polarized wave that sometimes cannot follow and be radiated will decrease. Also, when the R wave is selected, as the input microwave power increases, the electron temperature Te becomes too high. When the L wave is selected, there is a problem that it is difficult to ignite the plasma. In Patent Document 3, two rectangular waveguides are connected to form an L shape, and a reflection suppression part for the circular waveguide is provided at the right angle part of the L shape. At the incident ends of the two rectangular waveguides, by connecting to different magnetrons, circularly polarized waves are synthesized in the synthesis chamber connected to the right angle part of the aforementioned L shape. In Patent Document 3, although it is not described that the L wave is radiated into the reactor of the plasma processing apparatus, it is considered that the R wave or the L wave can be provided by adjusting the output phases of the two magnetrons. However, since the two rectangular waveguides forming the L shape propagate the microwave of the single mode TE10, the reflected wave caused by the plasma load in the processing chamber of the plasma processing apparatus can also be propagated. In order to maintain the axial ratio of the circularly polarized wave, a three stub tuner needs to be prepared in the rectangular waveguide part. Since the TE10 mode propagates, the reflected wave from the reactor also propagates in the aforementioned rectangular waveguide, and the axial ratio of the circularly polarized wave radiated into the reactor changes according to the process conditions of the plasma processing apparatus. [Means for Solving the Problem] A plasma processing apparatus according to an embodiment of the present invention includes: a processing chamber for performing plasma processing; a circular waveguide connected to the cavity of the processing chamber and capable of propagating microwave power in the TE11 mode; 2n solid-state element microwave sources, where n is a natural number greater than or equal to 2; a phase controller for controlling the phases of the microwave powers output from the solid-state element microwave sources respectively; 2n coaxial waveguide converters respectively connected to the solid-state element microwave sources for converting the microwave power from the TEM mode to the TE10 mode; and a polarization synthesis antenna having 2n cutoff waveguides "connected to the circular waveguide in the same plane perpendicular to the axial direction of the circular waveguide", the angle formed by the axial directions of adjacent cutoff waveguides is set to 180° / n, and the 2n cutoff waveguides are connected to the 2n coaxial waveguide converters in a one-to-one relationship. In the cutoff waveguides, the microwave power in the TE10 mode is blocked, and an evanescent field is excited toward the circular waveguide. [Effects of the Invention] According to the present invention, a plasma processing apparatus using microwaves can be provided. The microwaves can suppress reflected waves and radiate circularly polarized waves with a high axial ratio, and can selectively change the radiation pattern of polarization. Other problems and novel features can be clearly understood from the description of this specification and the attached drawings. Hereinafter, embodiments of the present invention will be described with reference to the drawings. [Embodiment 1] Using FIGS. 1 to 4, the configuration of Embodiment 1 will be described. FIG. 1 shows the overall configuration of the ECR plasma processing apparatus of Embodiment 1. In addition, the same reference numerals are given to the components common to FIG. 8, and repeated descriptions are omitted. The processing chamber 1 is a high-vacuum container that is evacuated to about 0.1 to 1 Pa by a vacuum pump 17. In this embodiment, a phase controller 7 is provided to control the output phase and the ON / OFF operation of the power of a plurality of solid-state element microwave sources 2. The plurality of solid-state element microwave sources 2 are respectively connected to coaxial waveguide converters 3, and the coaxial waveguide converters 3 are respectively connected to cutoff waveguides 4. The microwave power from the solid-state element microwave sources 2 is introduced from the coaxial waveguide converters 3 into the cutoff waveguides 4. In order to radiate microwaves into the cavity 6, here, a circular waveguide 5 with a diameter of 90 mm capable of propagating microwaves in the TE11 mode at 2.45 GHz is connected to a plurality of cutoff waveguides 4. Since the output frequency of the solid-state element microwave sources 2 is 2.45 GHz, the width of the cutoff waveguide 4 is set to 60 mm so as to block the microwaves in the TE10 mode, and the length up to the outermost circumference r = 45 mm of the circular waveguide 5 is set to 42.5 mm. The number of connections of the cutoff waveguides 4 is set to 2n (where n is a natural number greater than or equal to 2). A polarization synthesis antenna is formed at the connection portion between the circular waveguide 5 and the plurality of cutoff waveguides 4. The cutoff waveguide 4 is assumed to be a rectangular waveguide, but it can also be a circular waveguide. Figure 2 shows a horizontal cross-sectional view of the polarization synthesis antenna of Embodiment 1 (corresponding to the A-A cross-section shown in FIG. 1). The cutoff waveguide 4 of the polarization synthesis antenna shown in FIG. 2 is composed of n = 2, that is, four, and is connected in the same plane perpendicular to the axial direction of the circular waveguide 5 at azimuths of 0°, 90°, 180°, and 270°. Hereinafter, the cutoff waveguide 4 at the 0° azimuth is denoted as 4#1, the cutoff waveguide 4 at the 90° azimuth is denoted as 4#2, the cutoff waveguide 4 at the 180° azimuth is denoted as 4#3, and the cutoff waveguide 4 at the 270° azimuth is denoted as 4#4. Also, the four cutoff waveguides 4#1, 4#2, 4#3, and 4#4 and the parts connected to the coaxial waveguide converter 3 are respectively set as ports 1, 2, 3, and 4. In addition, when n ≥ 3, the cutoff waveguides are also connected in the same plane perpendicular to the axial direction of the circular waveguide 5 such that the angle formed by the axial directions of adjacent cutoff waveguides is 180° / n. Four coaxial waveguide converters 3 and solid element microwave sources 2 shown in FIG. 1 are respectively provided corresponding to the four cutoff waveguides 4. The output phases of the four solid element microwave sources 2 are controlled to 0π, 1 / 2π, π, and 3 / 2π as shown in FIG. 3A, for example, and are introduced into the coaxial waveguide converter 3, and are converted from the TEM mode to the TE10 mode. Since the microwave in the TE10 mode is in the form of an electromagnetic wave, it does not propagate in the cutoff waveguide 4, but the microwave power excites an evanescent field toward the circular waveguide 5 within a fixed distance of the cutoff waveguide 4. The excited evanescent field re-radiates the electromagnetic wave to the circular waveguide 5 by the method of "forming an electric field at the connection part of the cutoff waveguide 4 and the circular waveguide 5 of the polarization synthesis antenna". The electromagnetic wave radiated at this time becomes the TE11 mode propagating in the circular waveguide 5. Since the electromagnetic wave of the TE11 mode from the circular waveguide 5 has the same frequency as the electric field forming the evanescent field, which is 2.45 GHz, the electromagnetic wave of the TE11 mode propagating in the circular waveguide 5 also becomes 2.45 GHz. As described above, although the TE11 mode microwave is radiated from the circular waveguide 5 of the polarization synthesis antenna toward the cavity 6 as a result, the electromagnetic wave propagation from the microwave power source (wave source) is not directly utilized. The microwave power source (solid element microwave source 2) of this embodiment is only used to excite the evanescent field at the connection part of the cutoff waveguide 4 and the circular waveguide 5. FIG. 3A to FIG. 3C are explanatory diagrams of the R-wave coupling principle for phase control of a solid element microwave source according to the present invention. In FIG. 3A, it is an example of "controlling four solid element microwave sources 2 respectively by a phase controller 7 and setting the phases to the four cutoff waveguides 4#1, 4#2, 4#3, 4#4 to 0°, 90°, 180°, 270° respectively". As shown in FIG. 3B, at time O1, an electric field in the -Ex direction is coupled by the output phases of port 1 and port 3. Similarly, as shown in FIG. 3C, at time O2, an electric field in the +Ey direction is coupled by the output phases of port 2 and port 4. By controlling the difference between the phase at time O1 and the phase at time O2 to be 1 / 2π, a circularly polarized wave is radiated in the circular waveguide 5. The one-period timing diagram of FIG. 3A is an example of "synthesizing a circularly polarized wave of an R-wave by phase control of the output power from the solid element microwave source 2". In addition, if the timing diagram of FIG. 3A is reversed, that is, if the supply power phases to the cutoff waveguides 4#1, 4#2, 4#3, 4#4 are set to 270°, 180°, 90°, 0° respectively, a circularly polarized wave of an L-wave is formed in the circular waveguide 5. Furthermore, in FIG. 3A, although port 1 and port 3, port 2 and port 4 respectively excite evanescent fields at the same time point, even for the phase combinations of port 1 and port 4, port 2 and port 3, a rotating electric field, that is, a right-handed circularly polarized wave (R-wave), can be coupled in the circular waveguide 5. However, in this case, compared with the phase combinations of port 1 and port 3, port 2 and port 4 shown in FIG. 3A, the radiated power becomes 1 / 2. FIG. 4 shows the electromagnetic field simulation results of the electric field intensity distribution in the circular waveguide caused by the combination of the output phases of the solid element microwave source. As shown in FIG. 4, by controlling the microwave radiation phases of the solid element microwave sources 2 in the four cutoff waveguides 4 connected to the four directions of the circular waveguide 5, a circularly polarized wave of an R-wave and an L-wave, and elliptically polarized waves of -45°, 45°, 90°, 0° in the +Ey direction (where the clockwise direction of +Ey is positive and the counterclockwise direction is negative) are radiated in the circular waveguide 5 and can be radiated to the processing chamber 1 through the cavity 6. In this way, if the spatial configuration of the four cutoff waveguides 4 of the polarization synthesis antenna in FIG. 2 and the phase control in FIG. 3 are used to control the output phases of the solid element microwave sources 2 by the phase controller 7, the circularly polarized waves, elliptically polarized waves, and power of the electromagnetic waves radiated to the processing chamber 1 can be adjusted as shown in FIG. 4. The electromagnetic wave radiated from the circular waveguide 5 resonates in the cavity 6 of the plasma processing apparatus of the present embodiment while supplying electromagnetic wave power to the processing chamber 1 through the quartz window 13 and the shower plate 14. At this time, a static magnetic field B (not shown) in the processing chamber 1 is formed by the upper electromagnetic coil 9, the intermediate electromagnetic coil 10, and the lower electromagnetic coil 11, and the process gas G is supplied from the gas holes of the shower plate 14. The electrons wound around the magnetic field lines of the static magnetic field B are accelerated by the supplied electromagnetic wave to cause electron cyclotron resonance, and as a result, absorb the electromagnetic wave power, and an ECR surface (resonance point) of plasma is formed at a portion where the magnetic flux density is 875 G in the evacuated vacuum container of the processing chamber 1, and the plasma diffuses and is generated over time. [Embodiment 2] Using FIGS. 1, 2, and 5, the configuration of Embodiment 2 will be described. In Embodiment 1, since the cutoff waveguide 4 of the polarization synthesis antenna is directly connected to the circular waveguide 5, from the formation mechanism of the R wave, at the connection portion with the circular waveguide 5, the evanescent fields excited from port 1 and port 3 form electric fields in the ±Ex directions. On the other hand, at ports 2 and 4, electric fields in the ±Ey directions are formed. Therefore, a TE11 mode in which the electric field rotates can be radiated from the circular waveguide 5. As shown in FIGS. 3B and 3C, since the evanescent field excited in the cutoff waveguide 4 forms a linearly polarized wave in the circular waveguide 5, there is no necessity to specifically limit the connection portion between the cutoff waveguide 4 and the circular waveguide 5 to be circular. Therefore, in Embodiment 2, as shown in FIG. 5, the connection portions with the cutoff waveguides 4 in four directions are made into rectangles that are easy to manufacture and are connected to the circular waveguide 5. The microwave propagating in the rectangular coupling portion 501 in FIG. 5 is of the TE10 mode, but since it is similar in attitude to the TE11 mode that "propagates in the circular waveguide 5 connected to the lower part of the rectangular coupling portion 501", there is no excessive reflection. Therefore, even if the rectangular coupling portion 501 in FIG. 5 is provided, as in Embodiment 1, by controlling the phase of the solid-state element microwave source 2, microwaves capable of adjusting the circularly polarized wave, elliptically polarized wave, and power as shown in FIG. 4 can be radiated to the processing chamber 1. In view of the above, since the coupling electric fields caused by the evanescent field form linearly polarized waves in the ±Ex directions and the ±Ey directions respectively, as long as the above-mentioned linearly polarized waves can be propagated, the rectangular coupling portion 501 in FIG. 5 can also be of any shape. [Embodiment 3] With reference to FIGS. 1 and 6, the configuration of Example 3 will be described. In the method of radiating a conventional circularly polarized wave to a plasma processing apparatus, since the incident wave and the reflected wave are in the form of electromagnetic waves, the circular polarizer is designed for the configuration with the highest axial ratio of the circularly polarized wave in the plasma processing conditions or for each target process. Therefore, there is no selectivity of the circularly polarized wave to be radiated, and from the viewpoints of ignition and plasma density, the apparatus is generally designed for the circularly polarized wave of the R wave. In contrast, the axial ratio of the circularly polarized wave that can be provided by the plasma processing apparatus of this embodiment is such that, as long as it hardly depends on the process conditions and the output phase of the solid element microwave source 2 is controlled, an R wave, an L wave, and an elliptical circularly polarized wave can be selectively formed in the circular waveguide 5. Utilizing the aforementioned characteristics, in this Example 3, for example, at the fixed time t0 in FIG. 6, the output phase or the ON / OFF combination of the four solid element microwave sources 2 is controlled by the phase controller 7, and various microwave radiation forms of R wave radiation, L wave radiation, or elliptical circularly polarized wave can be radiated at the desired time point. FIG. 7 shows the simulation (HFSS (High Frequency Simulation Software)) results regarding "the change in the axial ratio in the circular waveguide due to the difference in the reflection coefficient of the processing apparatus for the circularly polarized wave generation apparatus based on a 1 / 4 phase plate as a comparative example (refer to FIG. 8) and the circularly polarized wave generation apparatus of this embodiment (refer to FIG. 1)". In this embodiment, the electromagnetic wave of the solid element microwave source 2 is not directly radiated from the circular waveguide 5 of the polarization synthesis antenna, but the circularly polarized wave is indirectly introduced into the circular waveguide 5 through the evanescent field caused by the cutoff waveguide 4. Therefore, as shown in FIG. 7, since it is difficult to receive the reflected wave from the processing chamber 1 due to the variation of the plasma load caused by the plasma etching process or the processing conditions of film formation such as the material gas G and the pressure, even if there is a variation in the plasma load, a circularly polarized wave with a high axial ratio can be radiated to the processing chamber 1. As shown in FIG. 7, in the configuration of this embodiment, different from the conventional 1 / 4 phase plate microwave plasma processing apparatus, and even without a reflection wave control device, i.e., a three stub tuner, in the waveguide path, the reflected wave can be suppressed (since the reflected wave is in the form of an electromagnetic wave, it cannot pass through the cutoff waveguide 4), so a circularly polarized wave with a high axial ratio can be radiated. Furthermore, through a phase combination as shown in FIG. 4, not only circularly polarized waves but also elliptically polarized waves with different azimuths can be emitted by controlling the output phase of the solid-state element microwave source 2, and the polarization emission pattern can be selectively changed by the film distribution or etching rate on the substrate w to be processed. As described above, since the R wave can continuously accelerate electrons in the magnetic field direction formed in the processing chamber 1, a high plasma density can be obtained. On the other hand, since the electron temperature Te increases as the microwave supply power increases, negative charges accumulate at the upper end of the fin of the FinFET, and precise control of the gate shape becomes difficult due to the electron shielding effect. In contrast, in the plasma processing apparatus according to this embodiment, the R wave and the L wave are selectively switched by the phase controller 7. Thereby, the electron temperature Te can be controlled, and the gate shape of the semiconductor element can be precisely processed. Also, since the absorption power of the plasma can be adjusted globally or regionally in the plasma region formed in the processing chamber 1 by selectively switching the R wave and the L wave, a uniform etching rate of the substrate w to be processed can of course be controlled to obtain a desired etching rate distribution according to applications such as the temperature distribution of the substrate stage to be processed. Here, although an example of etching has been described, the same applies to the case of film formation. In addition, the present invention is not limited to the above embodiments and also includes various modifications. For example, the above embodiments have been described in detail for easy understanding of the present invention and are not necessarily limited to having all the configurations described previously. Also, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, addition, deletion, or replacement of other configurations can be made to a part of the configuration of each embodiment. 1: Processing chamber 2: Solid-state element microwave source 3: Coaxial waveguide converter 4: Cutoff waveguide 5: Circular waveguide 6: Cavity 7: Phase controller 9: Upper electromagnetic coil 10: Intermediate electromagnetic coil 11: Lower electromagnetic coil 12: Yoke 13: Quartz window 14: Shower plate 15: Substrate stage to be processed 16: RF power supply 17: Vacuum pump w: Substrate to be processed G: Material gas 501: Rectangular coupling part [Fig. 1] Configuration diagram of an ECR plasma processing apparatus. [Fig. 2] Horizontal sectional view of the polarization synthesis antenna of Example 1. [Fig. 3A] Explanation diagram of the R-wave coupling principle according to the phase control of a solid-state element microwave source. [Fig. 3B] Explanation diagram of the R-wave coupling principle according to the phase control of a solid-state element microwave source. [Fig. 3C] Explanation diagram of the R-wave coupling principle according to the phase control of a solid-state element microwave source. [Fig. 4] Diagram of the electromagnetic field simulation results of the electric field intensity distribution in a circular waveguide caused by the combination of the output phases of a solid-state element microwave source. [Fig. 5] Horizontal sectional view of the polarization synthesis antenna of Example 2. [Fig. 6] Example of the combination of polarizations radiated at an arbitrary fixed time. [Fig. 7] Simulation results of the change in the axial ratio in a circular waveguide due to different reflection coefficients of the processing apparatus. [Fig. 8] Configuration diagram of a conventional ECR plasma processing apparatus. 1: Processing chamber 2: Solid-state element microwave source 3: Coaxial waveguide converter 4: Cutoff waveguide 5: Circular waveguide 6: Cavity 7: Phase controller 9: Upper electromagnetic coil 10: Intermediate electromagnetic coil 11: Lower electromagnetic coil 12: Yoke 13: Quartz window 14: Shower plate 15: Substrate stage to be processed 16: RF power supply 17: Vacuum pump G: Material gas w: Substrate to be processed

Claims

1. A plasma processing apparatus, characterized by comprising: a processing chamber for performing plasma processing; a circular waveguide connected to a cavity of the processing chamber for propagating microwave power in TE11 mode; 2n solid-state microwave sources, where n is a natural number greater than or equal to 2; a phase controller for controlling the phase of the microwave power output by each of the aforementioned solid-state microwave sources; 2n coaxial waveguide transducers connected to the aforementioned solid-state microwave sources respectively, for converting the microwave power generated by the aforementioned solid-state microwave sources from TEM mode to TE10 mode; and a polarization synthesized antenna comprising 2n cutoff waveguides connected to the aforementioned circular waveguides in the same plane perpendicular to the axial direction of the aforementioned circular waveguides, and a connection portion between the aforementioned cutoff waveguides and the aforementioned circular waveguides, wherein the angle between the axial directions of adjacent aforementioned cutoff waveguides is set to 180° / n, and the aforementioned 2n cutoff waveguides are connected to the aforementioned 2n coaxial waveguide transducers in a one-to-one relationship. In the aforementioned cutoff waveguide, the propagation of the microwaves in the TE10 mode is blocked, and the evanescent field is excited towards the aforementioned circular waveguide by the microwave power.

2. The plasma treatment apparatus as claimed in claim 1, wherein, The aforementioned evanescent field is an electric field formed at the connection between the aforementioned cutoff waveguide and the aforementioned circular waveguide, which radiates microwave power in TE11 mode to the aforementioned circular waveguide.

3. The plasma treatment apparatus as claimed in claim 1, wherein, The aforementioned 2n cutoff waveguides include a first cutoff waveguide and a second cutoff waveguide that are connected to the aforementioned circular waveguide in an opposite manner. The aforementioned 2n solid-state microwave sources include a first solid-state microwave source and a second solid-state microwave source. The aforementioned phase controller generates microwaves that are in the opposite phase to the microwaves generated by the first solid-state microwave source connected to the first cutoff waveguide. The second solid-state microwave source is connected to the aforementioned second cutoff waveguide.

4. The plasma treatment apparatus as described in claim 3, wherein, Assuming n=2, the aforementioned 2n cutoff waveguides include a third cutoff waveguide and a fourth cutoff waveguide that are connected to the aforementioned circular waveguide in an opposing manner. The aforementioned 2n solid-state microwave sources include a third solid-state microwave source and a fourth solid-state microwave source. The aforementioned phase controller generates microwaves whose phase is offset by 1 / 2π from the microwaves generated in the aforementioned first solid-state microwave source when connected to the aforementioned third cutoff waveguide, and generates microwaves whose phase is offset by 3 / 2π from the microwaves generated in the aforementioned first solid-state microwave source when connected to the aforementioned fourth cutoff waveguide.

5. The plasma treatment apparatus as claimed in claim 1, wherein, Let n=2, the connection between the aforementioned 2n cutoff waveguides and the aforementioned circular waveguides in the aforementioned polarization synthesized antenna is set to a rectangle.

6. The plasma treatment apparatus as claimed in claim 1, wherein, The aforementioned phase controller switches the phase of the microwaves generated by the aforementioned 2n solid-state microwave sources and / or the output of the aforementioned 2n solid-state microwave sources to ON / OFF, thereby switching the microwave emission mode of the microwaves propagating in the aforementioned circular waveguide and being emitted to the aforementioned processing chamber.

7. The plasma treatment apparatus as claimed in claim 6, wherein, The aforementioned phase controller switches the phase of the microwaves generated by the aforementioned 2n solid-state microwave sources and / or the output of the aforementioned 2n solid-state microwave sources to ON / OFF, thereby coupling any one of the right-hand circularly polarized microwave waves, the left-hand circularly polarized microwave waves, or the microwaves of elliptical polarized waves in a predetermined orientation contained in the same plane perpendicular to the axial direction of the aforementioned circular waveguide into the aforementioned circular waveguide.

8. The plasma treatment apparatus as claimed in claim 7, wherein, During plasma treatment in the aforementioned processing chamber, the microwave emission mode of the microwaves radiated into the aforementioned processing chamber is switched.

9. The plasma treatment apparatus as claimed in claim 8, wherein, The plasma treatment in the aforementioned processing chamber is either plasma etching or film formation.

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