JP2012190899A - Plasma processing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasma processing apparatus which uses micro waves and improves the uniformity of the plasma processing.SOLUTION: The plasma processing apparatus uses a ring-shaped cavity resonator 204 which comprises an electromagnetic wave introduction path for generating plasma installed concentrically with a central axis of a processing chamber, is connected to an output port of a branch circuit for distributing the electromagnetic wave to a plurality of output ports, and is installed concentrically with the electromagnetic wave introduction path for generating plasma. In the apparatus, the electromagnetic wave introduction path for generating plasma consists of a circular waveguide 201, the branch circuit consists of a plurality of waveguides arranged at equal angles with respect to the central axis the processing chamber, and the circular waveguide 201 has a generation mechanism 602 for generating the circular wave in order to excite a progressive wave inside the resonator.

Description

  The present invention relates to a plasma processing apparatus for plasma processing a substrate to be processed.

  Substrates used in the manufacture of semiconductor devices such as semiconductor memories and logic LSIs tend to be increased in diameter to improve productivity, and the most advanced semiconductor devices such as semiconductor memories use a silicon substrate having a diameter of 300 mm. Has become the mainstream. Furthermore, there is an opinion that a silicon substrate with a diameter of 450 mm is necessary, and it is thought that the trend of increasing the substrate diameter will continue. Although a plasma processing apparatus is used in the manufacturing process of these semiconductor devices, it is necessary to perform uniform plasma processing on the substrate to be processed, and the technical difficulty associated with increasing the diameter of the substrate to be processed tends to increase. .

  In order to perform uniform plasma processing on the substrate to be processed, naturally the distribution of plasma characteristics such as plasma density and temperature near the substrate to be processed is important, and the plasma distribution is optimized from the viewpoint of uniform plasma processing. Technology to do is important.

  Plasma processing equipment that generates plasma using microwave power has features such as being able to generate high-density plasma even under low pressure, and easily controlling the plasma distribution by adjusting the static magnetic field distribution in combination with a static magnetic field. Widely used in manufacturing the semiconductor device. In response to the above-mentioned trend of increasing the substrate diameter, it is important to control the plasma distribution in the microwave plasma processing apparatus.

  However, the wavelength of microwaves is as short as several centimeters to several tens of centimeters, and the microwave distribution is easily changed with dimensions on the same order as the wavelengths. Therefore, it tends to be difficult to optimize the microwave distribution in order to obtain a uniform plasma treatment over a wide range. As a plasma source for generating plasma using a microwave, for example, there are the following conventional techniques.

  Patent Document 1 discloses an example using a cavity resonator in which rectangular waveguides are arranged in a ring shape in order to radiate plasma generation microwaves into a processing chamber. A slot antenna is disposed on the plasma processing chamber side of the cavity resonator, and plasma can be generated by efficiently radiating microwave power to the plasma processing chamber. In order to excite a ring-shaped cavity resonator, a rectangular waveguide is connected to supply microwaves.

  Further, in Patent Document 2, the bias of the electromagnetic field in the cavity resonator is reduced by arranging the coaxial line coaxially with the ring-shaped cavity resonator in order to excite the ring-shaped cavity resonator in Patent Document 1.

JP-A-9-270386 JP 2007-35411 A

Masamitsu Nakajima, Microwave Engineering, Morikita Publishing

  In Patent Documents 1 and 2, the electromagnetic field in the ring-shaped cavity resonator forms a standing wave. FIG. 10 shows an example of the electric field intensity distribution in the ring-shaped cavity resonator. The part where the electric field is high is shown in dark color, and the part where the electric field is low is shown in light color. In the example of FIG. 10, a standing wave of an electric field is formed, and there are eight abdominal portions with strong electric field strength and nodal portions with low electric field strength. The positions of these abdominal nodes were fixed, and it was found that the strength of the electric field strength corresponding to the abdominal nodes in the cavity resonator may also occur in the plasma processing chamber.

  For this reason, plasma generated in the processing chamber may be non-uniform. Due to this non-uniformity, the plasma processing of the dielectric window that transmits microwaves while holding the vacuum processing chamber hermetically increases locally, adversely affects the uniformity of plasma processing applied to the substrate to be processed, etc. It was found that there might be a problem.

  The first problem to be solved by the present invention is to solve the non-uniformity caused by the standing wave generated in the ring-shaped cavity resonator.

  In Patent Document 2, the coaxial line is used for exciting the ring-shaped cavity resonator. However, it has been found that the coaxial line may be heated when high-power microwave power is applied.

  The second problem to be solved by the present invention is to provide a plasma processing apparatus improved from Patent Document 2 so that high-power microwave power can be input.

The present invention can solve the first problem by exciting a traveling wave in the ring-shaped cavity using circularly polarized waves.
Further, the present invention can solve the second problem by using a structure including a circular waveguide and a rectangular waveguide instead of the coaxial line for exciting the ring-shaped cavity resonator.

  The plasma processing apparatus of the present invention includes a processing chamber in which the inside is evacuated, a substrate electrode provided in the processing chamber on which a substrate to be processed is disposed, and plasma generation for generating plasma by plasma generating electromagnetic waves in the processing chamber A plasma processing apparatus having an apparatus, a supply system for supplying a processing gas into the processing chamber, and a vacuum exhaust system for exhausting the processing chamber, wherein the plasma is installed concentrically with the central axis of the processing chamber A branch circuit having a generation electromagnetic wave introduction path and distributing the electromagnetic wave to a plurality of output ports; and a ring-shaped cavity connected to the output port of the branch circuit and disposed concentrically with the introduction path of the plasma generation electromagnetic wave A resonator is provided, and the plasma generating electromagnetic wave introduction path is formed of a circular waveguide.

  The plasma processing apparatus of the present invention is further characterized in that the branch circuit is composed of a plurality of waveguides arranged at equal angles with respect to the central axis of the processing chamber.

  The plasma processing apparatus of the present invention is further characterized in that the circular waveguide is provided with a mechanism for generating circular polarization.

  According to the present invention, exciting a traveling wave in a ring-shaped cavity resonator can prevent a spatial variation in plasma density caused by a standing wave, and can achieve uniform plasma processing. Similarly, local scraping by the plasma of the dielectric window can be prevented.

  In addition, according to the present invention, a microwave power loss can be achieved by using a three-dimensional circuit system mainly composed of a circular waveguide and a rectangular waveguide for excitation of a cavity resonator, compared to an excitation system using a coaxial line. There is an effect of enabling a high output by reducing the voltage and improving the withstand voltage.

  In addition, compared to the conventional technology, the plasma density distribution can be made uniform, the in-plane uniformity of the plasma treatment applied to the substrate to be processed is improved, and local wear due to the plasma nonuniformity of the microwave introduction window is reduced. Can be prevented.

  In addition, high-power microwaves can be input, and the search range for optimum process conditions can be expanded. It also has the effect of reducing energy consumption since the loss of microwave power is reduced.

FIG. 1 is a schematic diagram illustrating the configuration of an etching apparatus using microwaves. FIG. 2 is a top view showing a ring-shaped cavity resonator and a rectangular waveguide and a circular waveguide for exciting the resonator. FIG. 3 is a side view showing a ring-shaped cavity resonator and a rectangular waveguide and a circular waveguide for exciting the resonator. FIG. 4 is an explanatory diagram showing the electric field distribution in the ring-shaped cavity resonator and in the circular waveguide. FIG. 5 is a diagram for explaining the excitation point of the ring-shaped cavity resonator. FIG. 6 is a schematic view for explaining an etching apparatus using the present invention. FIG. 7 is an explanatory view showing the structure of a circularly polarized wave generator. FIG. 8 is a top view showing the circular-rectangular converter. FIG. 9 is a side view showing the circular-rectangular converter. FIG. 10 is a diagram showing a conventional cavity resonator and internal electric field strength distribution.

  Hereinafter, embodiments of the plasma processing apparatus of the present invention will be described with reference to FIGS.

  First, referring to FIG. 1, for example, an etching apparatus described in Patent Document 2 will be briefly described. An electromagnetic wave generated by the high frequency power source 117 is transmitted to the coaxial line 101 by the coaxial waveguide converter 118 via the isolator 121 and the automatic matching machine 120 through the waveguide 119. A magnetron with an oscillation frequency of 2.45 GHz was used as the high frequency power source 117.

  Further, an electromagnetic wave is transmitted through the coaxial line 101, branched into a plurality of short coaxial lines 104 by a branch circuit 111 composed of a conductor 102 and a dielectric plate 103, and brought to a ring-shaped cavity resonator 105. A radial slot antenna 106 is provided below the ring-shaped cavity resonator 105 and is radiated to the processing chamber 114 through the dielectric window 107 and the shower plate 108. Quartz was used as the material for the dielectric window 107 and the shower plate 108.

  The shower plate 108 is not shown so that a processing gas supplied from a processing gas supply system (not shown) can be supplied into the processing chamber 114 in a shower-like manner through a minute gap between the dielectric window 107 and the shower plate 108. Many fine gas supply holes are provided. Further, a vacuum exhaust system (not shown) is connected to the processing chamber 114 and functions to evacuate the processing chamber 114 and maintain the processing chamber at a predetermined pressure suitable for processing.

  A substrate electrode 110 for placing a substrate to be processed 109 is installed in the processing chamber 114. A bias power source 115 is connected to the substrate electrode 110 via an automatic matching machine 116, and a bias potential can be applied to the substrate 109 to be processed. The frequency of the bias power supply 115 is 400 kHz.

  A static magnetic field generating means 112 is provided around the processing chamber 114, and a static magnetic field can be applied to the processing chamber 114. The generation of a static magnetic field (0.0875 Tesla in the case of a frequency of 2.45 GHz) in the processing chamber 114 facilitates the generation of plasma even in a high vacuum region, and enables plasma processing in a wide pressure range. Can be possible. Further, by adjusting the distribution of the static magnetic field, it is possible to adjust the plasma distribution by controlling the position where the electron cyclotron resonance occurs and the diffusion of the plasma.

  Also, a static magnetic field generating means 113 is provided inside the ring of the ring-shaped cavity resonator 105, so that the controllable range of the static magnetic field can be expanded.

Evaluation of the plasma etching apparatus shown in FIG. 1 revealed the following problems.
Problem 1: The coaxial waveguide section may generate heat when a high output is applied.
Problem 2: There may be a case where etching rate non-uniformity corresponding to the pattern of the electric field standing wave generated in the cavity resonator occurs. Similarly, local shaving corresponding to the electric field standing wave pattern may occur in the microwave introduction window.

  In response to Problem 1, the excitation structure of the ring-shaped cavity resonator was reviewed. The structure in which the coaxial waveguide is replaced with a circular waveguide and the branch circuit is configured using a rectangular waveguide was studied. In the examination, the characteristics of known microwave transmission lines such as a coaxial line, a circular waveguide, and a rectangular waveguide were confirmed by Non-Patent Document 1.

  Usually, when a waveguide is used, a frequency that can propagate only in a single mode is often used. For example, in the case of a microwave having a frequency of 2.45 GHz used in this embodiment, a waveguide having a cross section of 109.2 mm × 54.6 mm in WRJ-2 standard is often used. In this case, only the distribution called the TE10 mode of the rectangular waveguide is transmitted as the microwave electromagnetic field in the waveguide, which has the effect of stabilizing the electromagnetic field distribution in the waveguide.

  On the other hand, when a waveguide having a plurality of propagation modes is used, the electromagnetic field in the waveguide is superimposed on the plurality of propagation modes. For example, the mixing ratio of each propagation mode varies depending on the impedance of the load, which makes it difficult to stabilize the electromagnetic field distribution.

  In order to solve the above problem 1, the coaxial waveguide portion is replaced with a circular waveguide. It is known that the fundamental mode of the coaxial waveguide has a radial electric field from the central axis and has an electromagnetic field distribution similar to the TM01 mode of the circular waveguide. Therefore, to replace the coaxial waveguide portion with a circular waveguide, it is easy to use a circular waveguide that operates in the TM01 mode.

  However, since the TM01 mode of the circular waveguide is a high-order mode, the lowest-order TE11 mode is mixed as described above, and the stability of the electromagnetic field distribution may be impaired. Therefore, from the viewpoint of stabilizing the electromagnetic field distribution, a circular waveguide having a size capable of propagating only TE11 which is the lowest order mode in the frequency band of 2.45 GHz is used.

  Further, in the structure shown in FIG. 1, the branch circuit is a structure using a dielectric plate and a conductor plate. However, by replacing this with a rectangular waveguide, the loss of the microwave is reduced, and the high-power microwave is reduced. We examined the structure that enables input.

  A circular waveguide that operates in the TE11 mode is arranged on the central axis, and a method of exciting a ring-shaped cavity resonator using a plurality of rectangular waveguides branched from the circular waveguide has been studied.

  2 and 3 schematically show the structure obtained as a result of the examination. 2 is a top view and FIG. 3 is a side view. A circular waveguide 201 capable of propagating only the TE11 mode is arranged on the central axis of the ring-shaped cavity resonator 204 and is branched to a rectangular waveguide 203 via a matching cone 202.

  Although FIG. 2 shows an example of four branches, the number of rectangular waveguides to be branched is not limited to this. When the number of branches is one, it is difficult to excite the traveling wave in the ring-shaped cavity resonator, and the non-uniformity of the microwave distribution in the ring-shaped cavity resonator 204 may become apparent. is there. If the number of branches is too large, there is a drawback that the structure becomes complicated.

  Therefore, 3 or more and 5 or less are considered desirable. The matching cone 202 is adjusted in height, lower diameter, and upper diameter so as to efficiently transmit the microwave power from the circular waveguide 201 to the rectangular waveguide 203. Further, a matching ridge 205 is provided in the rectangular waveguide 203, and the shape is adjusted so that the microwave power from the rectangular waveguide 203 is efficiently transmitted to the ring-shaped cavity resonator 204.

  As a material for the circular waveguide, the rectangular waveguide, the matching ridge, and the matching cone, it is desirable to use a metal having high conductivity in order to reduce the microwave loss. In this embodiment, aluminum is used. Further, the inner surface exposed to the microwave electromagnetic field may be covered with a material having high conductivity such as silver.

  In the circular waveguide 201, a microwave that is circularly polarized by a mechanism described later is introduced. The polarization plane of the microwave circularly polarized in the circular waveguide 201 (a plane composed of the traveling direction of the microwave and the direction of the electric field vector on the central axis) rotates once in one period of the microwave. Each rectangular waveguide 203 branched into four is arranged at a position obtained by dividing one rotation of 360 degrees into four equal parts every 90 degrees in the θ direction shown in FIG.

  Since each rectangular waveguide 203 has the same length and structure, microwaves having phases different from each other by 90 degrees are excited at the connection portion with the ring-shaped cavity resonator 204. The four connecting portions of each rectangular waveguide 203 and the ring-shaped cavity resonator 204 are at positions that are 90 degrees apart from each other in the θ direction of the ring-shaped cavity resonator 204, and microwaves that are 90 degrees out of phase from each position. You will be excited.

  The matching ridge 205 and the matching cone 202 may be omitted when the degree of microwave mismatch is not significant or when the reflected wave can be suppressed by the microwave automatic matching machine. Further, the matching ridge may be omitted, and the reflected wave from the branch circuit and the ring-shaped cavity resonator excitation unit may be suppressed only by the matching cone. Further, other known matching means such as inserting a conductive rod into the waveguide portion may be used.

  Although FIG. 2 shows an example using the quadrangular rectangular waveguide 203, the electromagnetic field distribution, the number of branches, and the position in the ring-shaped cavity resonator will be described. FIG. 4 shows a diagram describing the electric field vectors of each part such as a ring-shaped cavity resonator. The electric field vector 403 in the circular waveguide is the circular waveguide TE11 mode as described above. The electric fields 401 and 402 in the ring-shaped cavity resonator indicate that the directions are different by 180 degrees in the direction perpendicular to the paper surface of FIG. In the ring-shaped cavity resonator, the dimensions are such that microwaves for five wavelengths enter in the θ direction of FIG. It is known that the electric field 403 of the circular waveguide TE11 mode can be expressed by the following equation (1).

  From equation (1), it can be seen that the electric field also changes sinusoidally for one period when the angle θ is in the range of 0 to 360 degrees. On the other hand, in the ring-shaped cavity resonator, microwaves for five wavelengths exist in the range of the angle θ from 0 to 360 degrees, and therefore, a sinusoidal change for five cycles is performed in this range.

  FIG. 5 shows a graph illustrating the above phase relationship. The horizontal axis represents the angle θ, and the vertical axis represents the phase of the microwave. In the ring-shaped cavity resonator, there are five straight lines corresponding to the phase change of five wavelengths when the angle θ is between 0 and 360 degrees.

  Similarly, in the circular waveguide, there is a single straight line corresponding to a phase change for one cycle of the sine wave when the angle θ is between 0 and 360 degrees. The intersections of these straight lines are four points with angles θ of 0, 90, 180, and 270 degrees. Since the phase of the wave in the circular waveguide coincides with the phase of the wave in the ring-shaped cavity at these intersections, electromagnetic field mismatch at each connection portion does not occur, which is desirable as an excitation point. Four rectangular waveguides corresponding to these intersections were connected to the ring-shaped cavity resonator at angles θ of 0, 90, 180, and 270 degrees to form excitation points.

  Similarly, when a mode that resonates with microwaves for four wavelengths is used as a ring-shaped cavity, the phase of the wave in the circular waveguide and the ring-shaped cavity resonance at three angles θ of 0, 120, and 240 degrees. Since the phases in the chamber match, it is desirable to excite at these three points. The excitation point can be similarly determined when other resonance modes of the ring-shaped cavity resonator are used.

  By arranging the rectangular waveguides for excitation equally in the θ direction, it is possible to minimize the nonuniformity of the microwave power distribution in the ring-shaped cavity resonator. That is, in the case of three rectangular waveguides, it is desirable that the interval be 120 degrees, if four are 90 degrees, and if five are 72 degrees. When more waveguides are used, nonuniformity due to the excitation point in the ring-shaped cavity resonator is reduced, but there is a disadvantage that the structure becomes complicated. The same effect can be obtained even if the waveguide used for exciting the ring cavity resonator has a structure other than the rectangular waveguide. For example, a circular waveguide, a coaxial waveguide, a microstrip line, or the like may be used.

  As a case where the number of branches does not satisfy the above principle, a case where a ring-shaped cavity resonator resonating with microwaves for five wavelengths is excited by three rectangular waveguides arranged at intervals of 120 degrees was examined. It was found that traveling waves corresponding to four wavelengths were mixed and excited in the ring-shaped cavity resonator corresponding to the three excitation points. The ring-shaped cavity is electromagnetically coupled to the outside of the cavity by means of a slot antenna or an exciting rectangular waveguide. If there is no significant deviation from the desired mode, circular polarization and excitation at multiple locations Thus, it was found that a traveling wave can be excited in the ring-shaped cavity resonator.

  Next, as a modification of the structure shown in FIG. 4, the case where excitation was performed by two rectangular waveguides at intervals of 180 degrees was examined. In this case, the traveling wave could not be excited in the ring-shaped cavity resonator and became a standing wave. In general, when a clockwise traveling wave and a counterclockwise traveling wave exist with equal amplitude, a complete standing wave is generated, and when a deviation occurs in the amplitude, a traveling wave component is generated. When excitation is performed by two rectangular waveguides at intervals of 180 degrees, excitation is performed at a position where θ is different by 180 degrees with a phase difference of 180 degrees. The structure is substantially symmetrical with respect to each rectangular waveguide, and clockwise and counterclockwise traveling waves are generated with equal amplitude from each rectangular waveguide. In such a structure, it is impossible to cancel either the clockwise traveling wave or the counterclockwise traveling wave, and the traveling wave cannot be excited because both exist with equal amplitude.

  FIG. 6 shows an improved plasma processing apparatus. Descriptions of portions overlapping with the plasma processing apparatus shown in FIG. 1 will be omitted, and description will be made mainly focusing on the differences. In FIG. 1, microwaves are transmitted to the ring-shaped cavity resonator by the coaxial line 101, but are changed to the circular waveguide 201. Along with this, the coaxial waveguide converter 118 is changed to a circular rectangular converter 601.

  The circular-rectangular converter 601 has a rectangular waveguide as an input port and a circular waveguide as an output port, and efficiently converts a microwave generated from the rectangular waveguide into a TE11 mode of the circular waveguide. Have a job.

  A circularly polarized wave generator 602 is disposed between the circular rectangular converter 601 and the circular waveguide 201. The circularly polarized wave generator 602 has a function to circularly polarize a microwave input as a linearly polarized wave of the circular waveguide TE11 mode. The circularly polarized microwave is transmitted from the circular waveguide 201 to the ring-shaped cavity resonator 204 through the rectangular waveguide 203 described with reference to FIG. As a ring-shaped cavity resonator, the dimensions were such that microwaves for five wavelengths entered the range of 360 degrees in the θ direction shown in FIG.

  A radial slot antenna 106 is provided on the processing chamber side of the ring-shaped cavity resonator, and microwaves in the ring-shaped cavity resonator are emitted to the processing chamber side to generate plasma in the processing chamber. A cavity 603 is provided between the radial slot antenna 106 and the dielectric window 107. In general, the locational non-uniformity of the microwave power is large just below the slot antenna due to the positional relationship with the antenna opening, but the provision of the cavity 603 has the effect of alleviating the non-uniformity due to the slot antenna arrangement. .

  In addition, there is an effect that the reflection and distribution of the microwave can be adjusted by adjusting the height of the hollow portion 603 (distance between the slot antenna 106 and the dielectric window 107). The cavity 603 may be omitted when there is no significant local unevenness due to the slot antenna.

  Various known structures can be used as the circularly polarized wave generator. In this example, a known structure shown in FIG. 7 was used. The circular waveguide 701 is loaded with a dielectric plate 703. The electric field vector of the circular waveguide TE11 mode at the input port is schematically shown. The microwave incident from the input port is linearly polarized wave, and as shown in FIG. 7, the dielectric plate 703 and the microwave electric field vector are arranged so as to intersect at an angle of 45 degrees on the central axis. As the dielectric plate 703, a dielectric having a small loss with respect to the microwave 702 can be used. In this embodiment, quartz is used. By adjusting the thickness and length of the dielectric plate 703, the microwave at the output port can be circularly polarized.

  8 and 9 show the structure of the circular rectangle converter. FIG. 8 shows a top view and FIG. 9 shows a side view. A rectangular waveguide portion 801 whose input side section is a rectangular waveguide and a circular waveguide section 802 whose output side section is a circular waveguide are connected. Furthermore, it also has a function of bending the microwave traveling direction by 90 degrees, contributing to the miniaturization of the apparatus. The TE11 mode electric field distribution of the circular waveguide portion is also shown. The dielectric plate of the circularly polarized wave generator shown in FIG. 7 was installed with an inclination of 45 degrees with respect to the circular waveguide TE11 mode electric field.

  The present invention is not limited to the plasma etching apparatus shown in the drawings, but can be applied to plasma etching apparatuses using other plasma generation methods. Further, for example, plasma CVD and plasma ashing can be applied as other plasma processing.

DESCRIPTION OF SYMBOLS 101 Coaxial line 102 Conductor 103 Dielectric board 104 Short coaxial line 105 Ring-shaped cavity resonator 106 Slot antenna 107 Dielectric window 108 Shower plate 109 Substrate 110 Substrate electrode 111 Branch circuit 112 Static magnetic field generating means 113 Static magnetic field generation Generation means 114 Processing chamber 115 Bias power supply 116 Automatic matching machine 117 High-frequency power supply 118 Coaxial waveguide converter 120 Automatic matching machine 119 Waveguide 121 Isolator 201 Circular waveguide 202 Matching cone 203 Rectangular waveguide 204 Ring-shaped cavity Resonator 205 Matching ridge 401 Electric field in ring cavity resonator 402 Electric field in ring cavity resonator 403 Electric field vector in circular waveguide 601 Circular rectangular converter 602 Circular polarization generator 603 Cavity 701 Circular waveguide 702 microwave 703 Dielectric plate 801 Rectangular waveguide portion 802 Circular waveguide portion

Claims (3)

A processing chamber in which the inside is evacuated,
A substrate electrode provided in the processing chamber and on which a substrate to be processed is disposed;
A plasma generator for generating plasma by plasma generating electromagnetic waves in the processing chamber;
A supply system for supplying a processing gas into the processing chamber;
In a plasma processing apparatus having a vacuum exhaust system for exhausting the processing chamber,
An electromagnetic wave introduction path for generating a plasma installed concentrically with the central axis of the processing chamber;
A branch circuit for distributing the electromagnetic wave to a plurality of output ports;
A ring-shaped cavity resonator connected to the output port of the branch circuit and disposed concentrically with the introduction path of the plasma generating electromagnetic wave;
A plasma processing apparatus, wherein the plasma generating electromagnetic wave introduction path is constituted by a circular waveguide. The plasma processing apparatus according to claim 1,
The plasma processing apparatus, wherein the branch circuit includes a plurality of waveguides arranged at equal angles with respect to the central axis of the processing chamber. The plasma processing apparatus according to claim 1 or 2,
A plasma processing apparatus comprising a circularly polarized wave generating mechanism in the circular waveguide.

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