Plasma processing device

Abstract

Provided is a plasma processing device using microwaves, capable of suppressing a reflected wave and emitting a circularly polarized wave having a high axial ratio, and also capable of selectively changing the mode of emission of the polarized wave. This plasma processing device comprises: 2n solid-state element microwave sources 2; 2n coaxial waveguide converters 3 that are respectively connected to the solid-state element microwave sources and that convert microwave power from a TEM mode to a TE10 mode; and a polarization synthesis antenna provided with 2n cut-off waveguides 4 that are connected to a circular waveguide at every 180° / n on the same plane perpendicular to the axial direction of the circular waveguide 5. The 2n cut-off waveguides are connected with the 2n coaxial waveguide converters in a one-to-one relationship, TE10-mode microwave power is cut off in the cut-off waveguides, and an evanescent field is excited toward the circular waveguide.

Description

Plasma processing equipment

[0001] The present invention relates to an ECR (Electron Cyclotron Resonance) plasma processing apparatus using microwaves.

[0002] In recent years, the integration density of semiconductor devices has increased, requiring finer processing, i.e., improved processing accuracy. At the same time, it has become increasingly important to improve the uniformity of the etching rate and the CD (Critical Dimension) value within the wafer surface. Furthermore, the materials to be etched have changed from single-layer films to multilayer films, and multi-step etching, in which the etching conditions are changed during the processing of each multilayer film, has become common. In this case, factors affecting the etching uniformity vary from step to step, making it difficult to achieve uniformity of the etching rate and axial symmetry at the completion of etching of each multilayer film.

[0003] Dry etching is one of the micro-etching techniques used in the semiconductor industry, and plasma-based dry etching is particularly common. Plasma uses collisions between electrons and the molecules or atoms of the process gas to excite them, generating ions and radicals. Plasma processing equipment achieves anisotropic etching with ions and isotropic etching with radicals. Electron cyclotron resonance (ECR) is one plasma source. Because ECR can generate high-density plasma, it is used to improve the withstand voltage of DRAM in semiconductor devices and to create high-capacity capacitors.

[0004] 8 shows the configuration of a conventional ECR etching apparatus. A 2.45 GHz microwave emitted from a magnetron 72 propagates through an isolator 73, a rectangular waveguide 74, and a three-stub tuner 75 in the TE10 mode, and then the propagation mode (or mode) is converted to the TE11 mode by a circular-to-rectangular waveguide converter 76. The circular-to-rectangular waveguide converter 76 has a diameter of 90 mm so that the 2.45 GHz microwave can pass through in the fundamental TE11 mode propagation mode. To generate axially symmetric microwave radiation, a quartz dielectric quarter-wave plate 8 is used to form a circularly polarized wave. By rotating the microwave in the TE11 mode propagation mode over time, the microwave's electric field distribution becomes axially symmetric and is radiated into the cavity 6. In order to propagate the microwave as a circularly polarized wave within the circular waveguide 5, the aforementioned quarter-wave plate 8 is inserted into the circular waveguide 5 at an angle of 45 degrees to the plane of polarization of the linearly polarized wave in the TE11 mode.

[0005] The circularly polarized microwaves incident on the cavity 6 are introduced into the processing chamber 1 through the quartz window 13 and shower plate 14 located at the top of the processing chamber 1, which is covered by the upper electromagnetic coil 9, middle electromagnetic coil 10, and lower electromagnetic coil 11. The electric field caused by the microwave and the magnetic field formed perpendicular to it cause electron cyclotron motion. When the microwave frequency is 2.45 GHz, electrons perpendicular to the magnetic field have their direction of travel bent by the Lorentz force, and the electrons gradually begin to move in circles. The magnetic flux density B at this time is calculated using the formula: fc = eB / 2πme (e is the electron charge, 1.6 × 10 －１９ C, me is the electron mass 9.1 × 10 －３１ Kg, fc is 2.45 GHz), electron cyclotron resonance occurs when the power is set to 875 G, increasing the probability of collision between electrons and gas molecules in the processing chamber 1, making it possible to generate high-density plasma even under low pressure.

[0006] The pressure in the processing chamber 1 is reduced to about 1 Pa by the vacuum pump 17 during the etching process. １１ cm －３The above-mentioned high-density plasma can be obtained. Furthermore, the plasma formation and independent ion energy can be controlled by the RF power supply 16 applied to the substrate stage 15, enabling precise shape control. Furthermore, to improve the in-plane uniformity of the substrate w to be processed, a circularly polarized wave is introduced into the processing chamber 1 using a quarter-wave plate 8.

[0007] The axial ratio of the circularly polarized wave generated by the quarter-wave plate 8 of the prior art does not take into account reflection from the processing chamber 1, and therefore, when the plasma density in the processing chamber 1 reaches a certain value, a reflected wave is generated from the processing chamber 1. This reflected wave forms a standing wave with the incident wave, which hinders the rotation of the TE11 mode electric field in the circular waveguide 5 and reduces the axial ratio of the circularly polarized wave to be input into the processing chamber 1. The axial ratio is defined as the circularity of the circularly polarized wave, with 1 being the highest circularity ratio.

[0008] In order to perform uniform plasma processing on the substrate w to be processed, it goes without saying that the distribution of plasma characteristics such as plasma density and temperature near the substrate w to be processed is important, and technology for optimizing the plasma distribution from the perspective of uniform plasma processing is important.

[0009] Plasma processing equipment that generates plasma using microwave power has the advantage of being able to generate high-density plasma even under low pressure, and when used in combination with a static magnetic field, the plasma distribution can be easily controlled by adjusting the static magnetic field distribution. This makes them widely used in the manufacturing of semiconductor processing equipment. In response to the trend toward larger substrate diameters, controlling the plasma distribution is also important in microwave plasma processing equipment. However, microwave wavelengths are short, ranging from a few centimeters to several dozen centimeters, and the microwave electric field distribution on semiconductor substrates with dimensions on the same order as the wavelength is easily variable. Therefore, optimizing the microwave distribution to achieve uniform plasma processing over a wide area presents a challenge.

[0010] In a plasma source that generates plasma using microwaves, the following prior art documents, for example, are known as conventional techniques that use circularly polarized microwaves.

[0011] JP 2010-192750 A JP 2003-188152 A JP 2006-339547 A

[0012] Michael A. Lieberman et. al, “Principles of Plasma Discharges and Materials Processing”John Wiley & Sons, Inc. (2005)

[0013] The requirements for the etching of structural patterns in semiconductor devices, particularly the shape accuracy and uniformity of etching rates in gate processing, which govern the operating characteristics of semiconductor devices, are becoming increasingly stringent. To solve the aforementioned problems, many techniques for controlling the distribution of ECR ​​plasma used in dry etching have been proposed.

[0014] In the prior art disclosed in Patent Document 1, a single-mode microwave such as TE10 is transmitted from a rectangular waveguide connected to a magnetron by inserting a ¼λg wave plate (λg shown here is the wavelength of the electromagnetic wave in a φ90 mm circular waveguide at 2.45 GHz) into a circular waveguide connected to the rectangular waveguide, forming a rotating electric field in TE11 mode within the circular waveguide, and radiating it into the processing chamber of a plasma processing apparatus, thereby achieving a high uniformity in etching rate. However, the phase plate in Patent Document 1 forms an angle of 45° clockwise with the main polarization plane, and therefore can only radiate right-handed electromagnetic waves (hereinafter, right-handed electromagnetic waves will be referred to as R-waves and left-handed electromagnetic waves as L-waves) during the etching process.

[0015] As shown in Non-Patent Document 1, in an environment with a magnetic field B, the electromagnetic energy of R waves is continuously accelerated by the Lorentz force into electrons wrapped around the magnetic field lines, so that the microwave energy is easily absorbed by the electrons, increasing the electron temperature Te. This causes an electron shelling effect on the top of fine patterns such as FinFETs in semiconductor device structures, and as a result, the ion trajectories incident on the wall surfaces of the fins in the dense and sparse portions of the device pattern on the substrate are bent by the negative electric field of the electron shelling effect, resulting in the formation of notches of varying degrees at the base of the fins of the FinFETs.

[0016] In Patent Document 2, a cross slot is used at the connection between the rectangular waveguide and the circular waveguide in order to radiate rotational TE11 mode electromagnetic waves into the circular waveguide, but like Patent Document 1, Patent Document 2 can only radiate either R-waves or L-waves during the plasma processing process, and because the dimensions and angle of the cross slot are designed according to fixed process conditions, it cannot follow changes in impedance within the processing chamber, which can result in a decrease in the axial ratio of the radiated circularly polarized waves. Furthermore, when R-waves are selected, the electron temperature Te becomes too high as the input microwave power increases, and when L-waves are selected, there is the problem of difficulty in plasma ignition.

[0017] Patent Document 3 connects two rectangular waveguides in an L shape, with a reflection suppression section at the right angle of the L shape, connecting them to a circular waveguide. By connecting different magnetrons to the input ends of the two rectangular waveguides, circularly polarized waves are combined in a combining chamber connected to the right angle of the L shape. Patent Document 3 does not describe radiating L waves into the reactor of a plasma processing device, but it is believed that adjusting the output phase of the two magnetrons can provide R waves or L waves. However, since the two L-shaped rectangular waveguides can propagate single-mode TE10 microwaves, reflected waves due to the plasma load in the processing chamber of the plasma processing device can also propagate. To maintain the axial ratio of the circularly polarized waves, a three-stub tuner must be provided in the rectangular waveguide section. Furthermore, since the TE10 mode propagates, reflected waves from the reactor also propagate within the rectangular waveguide. Therefore, the axial ratio of the circularly polarized waves radiated into the reactor changes depending on the process conditions of the plasma processing device.

[0018] A plasma processing apparatus according to one embodiment of the present invention includes a processing chamber for performing plasma processing, a circular waveguide coupled to a cavity of the processing chamber and capable of propagating microwave power in TE11 mode, 2n solid-state microwave sources, where n is a natural number of 2 or greater, a phase controller for controlling the phase of the microwave power output by each of the solid-state microwave sources, 2n coaxial-waveguide converters connected to each of the solid-state microwave sources and converting the microwave power from TEM mode to TE10 mode, and a polarization combining antenna having 2n cutoff waveguides connected to the circular waveguides on the same plane perpendicular to the axial direction of the circular waveguides, the angle between adjacent cutoff waveguides in the axial direction being 180° / n, and the 2n cutoff waveguides are connected to the 2n coaxial-waveguide converters in a one-to-one relationship, and the TE10 mode microwave power is blocked in the cutoff waveguides and an evanescent field is excited toward the circular waveguides.

[0019] According to the present invention, it is possible to provide a plasma processing apparatus that uses microwaves, which can radiate circularly polarized waves with a high axial ratio by suppressing reflected waves, and can selectively change the radiation form of the polarized waves. Other objects and novel features will become apparent from the description of this specification and the accompanying drawings.

[0020] FIG. 1 is a configuration diagram of an ECR plasma processing apparatus. FIG. 2 is a horizontal cross-sectional view of a polarization combining antenna of Example 1. FIG. 3 is an explanatory diagram of the principle of R-wave coupling by phase control of a solid-state microwave source. FIG. 4 is an explanatory diagram of the principle of R-wave coupling by phase control of a solid-state microwave source. FIG. 5 is an explanatory diagram of the principle of R-wave coupling by phase control of a solid-state microwave source. FIG. 6 is a diagram of the electromagnetic field simulation results of the electric field strength distribution in a circular waveguide by combinations of solid-state microwave source output phases. FIG. 7 is a horizontal cross-sectional view of a polarization combining antenna of Example 2. FIG. 8 is an example of combinations of polarizations radiated within an arbitrary fixed time. FIG. 9 is a simulation result of changes in the axial ratio in a circular waveguide due to differences in the reflection coefficient of the processing apparatus. FIG. 10 is a configuration diagram of a conventional ECR plasma processing apparatus.

[0021] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0022] The configuration of Example 1 will be described using Figures 1 to 4. Figure 1 shows the overall configuration of an ECR plasma processing apparatus of Example 1. Components common to those in Figure 8 are assigned the same reference numerals, and duplicated descriptions will be omitted. The processing chamber 1 is a high-vacuum vessel depressurized to approximately 0.1 to 1 Pa by a vacuum pump 17. In this example, a phase controller 7 is provided, which can control the output phase and ON / OFF operation of the power of multiple solid-state microwave sources 2. Each of the multiple solid-state microwave sources 2 is connected to a coaxial-waveguide converter 3, and each of the coaxial-waveguide converters 3 is connected to a cutoff waveguide 4, and microwave power from the solid-state microwave source 2 is introduced from the coaxial-waveguide converter 3 to the cutoff waveguide 4.

[0023] In order to radiate microwaves into the cavity 6, a circular waveguide 5 having a diameter of 90 mm, capable of propagating microwaves in the TE11 mode at 2.45 GHz, is connected to multiple cutoff waveguides 4. Since the output frequency of the solid-state microwave source 2 is 2.45 GHz, the width of the cutoff waveguide 4 is set to 60 mm, and the length up to the outermost periphery r = 45 mm of the circular waveguide 5 is set to 42.5 mm, so that microwaves in the TE10 mode can be blocked. The number of connected cutoff waveguides 4 is set to 2n (where n is a natural number greater than or equal to 2). A polarization combining antenna is formed at the connection between the circular waveguide 5 and the multiple cutoff waveguides 4. Although the cutoff waveguide 4 is assumed to be a rectangular waveguide, it may also be a circular waveguide.

[0024] Figure 2 shows a horizontal cross section of the polarization combining antenna of Example 1 (corresponding to the A-A cross section shown in Figure 1). The polarization combining antenna shown in Figure 2 has n=2, i.e., four cutoff waveguides 4, which are connected at 0°, 90°, 180°, and 270° angles on the same plane perpendicular to the axial direction of the circular waveguide 5. Depending on the angle, the cutoff waveguide 4 at 0° angle will be referred to as 4#1, the cutoff waveguide 4 at 90° angle as 4#2, the cutoff waveguide 4 at 180° angle as 4#3, and the cutoff waveguide 4 at 270° angle as 4#4. The points where the four cutoff waveguides 4#1, 4#2, 4#3, and 4#4 are connected to the coaxial-waveguide converter 3 will be referred to as port 1, port 2, port 3, and port 4, respectively. Even when n≧3, the cutoff waveguides are connected on the same plane perpendicular to the axial direction of the circular waveguide 5 so that the angle between the axial directions of adjacent cutoff waveguides is 180° / n.

[0025] Four coaxial-waveguide converters 3 and four solid-state microwave sources 2 shown in FIG. 1 are provided corresponding to the four cutoff waveguides 4. The output phases of the four solid-state microwave sources 2 are controlled to, for example, 0π, 1 / 2π, π, and 3 / 2π as shown in FIG. 3A , and are introduced into the coaxial-waveguide converter 3, where they are converted from TEM mode to TE10 mode. Because TE10 mode microwaves are in the form of electromagnetic waves, they do not propagate within the cutoff waveguide 4. Instead, their microwave power excites an evanescent field toward the circular waveguide 5 within a certain distance of the cutoff waveguide 4. The excited evanescent field forms an electric field at the junction between the cutoff waveguide 4 and the circular waveguide 5 of the polarization combining antenna, thereby radiating an electromagnetic wave again to the circular waveguide 5. The radiated electromagnetic wave is in TE11 mode and propagates within the circular waveguide 5. The TE11 mode electromagnetic wave from the circular waveguide 5 has a frequency of 2.45 GHz, which is the same frequency as the frequency at which the electric field of the evanescent field is formed, and therefore the TE11 mode electromagnetic wave propagating through the circular waveguide 5 also has a frequency of 2.45 GHz.

[0026] As explained above, microwaves in TE11 mode are ultimately radiated from the circular waveguide 5 of the polarization combining antenna toward the cavity 6, but electromagnetic wave propagation from the microwave power supply (wave source) is not directly utilized. The microwave power supply (solid-state microwave source 2) of this embodiment is used solely to excite an evanescent field at the junction between the cutoff waveguide 4 and the circular waveguide 5.

[0027] Figures 3A-3C are diagrams illustrating the principle of R-wave coupling by phase control of solid-state microwave sources according to the present invention. Figure 3A shows an example in which four solid-state microwave sources 2 are each controlled by a phase controller 7, with the phases of the four cutoff waveguides 4#1, 4#2, 4#3, and 4#4 set to 0°, 90°, 180°, and 270°, respectively. As shown in Figure 3B, at time O1, an electric field in the -Ex direction is coupled by the output phases of ports 1 and 3. Similarly, as shown in Figure 3C, at time O2, an electric field in the +Ey direction is coupled by the output phases of ports 2 and 4. By controlling the phase difference between time O1 and time O2 to 1 / 2π, a circularly polarized wave is radiated into the circular waveguide 5. The timing chart for one period in Figure 3A shows an example in which a circularly polarized R-wave is synthesized by phase control of the output power from the solid-state microwave sources 2.

[0028] 3A is reversed, i.e., the phases of the power supplied to cutoff waveguides 4#1, 4#2, 4#3, and 4#4 are set to 270°, 180°, 90°, and 0°, respectively, and L-wave circularly polarized waves are formed in circular waveguide 5. Furthermore, in FIG. 3A, ports 1 and 3, and ports 2 and 4 excite evanescent fields at the same timing, but even with the phase combinations of ports 1 and 4 and ports 2 and 3, a rotating electric field, i.e., right-handed circularly polarized waves (R-waves), can be coupled to circular waveguide 5. However, in this case, the radiated power is half that of the phase combinations of ports 1 and 3 and ports 2 and 4 shown in FIG. 3A.

[0029] Figure 4 shows the results of an electromagnetic field simulation of the electric field intensity distribution within the circular waveguide depending on the combination of the output phase of the solid-state microwave source. As shown in Figure 4, by controlling the microwave radiation phase of the solid-state microwave source 2 to the cutoff waveguides 4 connected to the four corners of the circular waveguide 5, circularly polarized R-waves and L-waves, and elliptically polarized waves at -45°, 45°, 90°, and 0° in the +Ey direction (clockwise around +Ey is positive, and counterclockwise around +Ey is negative), are radiated into the circular waveguide 5, which then travels through the cavity 6 and is radiated into the processing chamber 1. In this way, by controlling the spatial arrangement of the four cutoff waveguides 4 of the polarization combining antenna shown in Figure 2 and the output phase of the solid-state microwave source 2 using the phase controller 7 and the phase control shown in Figure 3, it is possible to adjust the circular polarization, elliptically polarized waves, and power of the electromagnetic waves radiated into the processing chamber 1, as shown in Figure 4.

[0030] The electromagnetic waves emitted from the circular waveguide 5 resonate in the cavity 6 of the plasma processing apparatus of this embodiment, passing through the quartz window 13 and shower plate 14, and supplying electromagnetic power to the processing chamber 1. At this time, a static magnetic field B (not shown) is formed in the processing chamber 1 by the upper electromagnetic coil 9, middle electromagnetic coil 10, and lower electromagnetic coil 11, and a process gas G is supplied through the gas holes in the shower plate 14. Electrons wrapped around the magnetic field lines of the static magnetic field B are accelerated by the supplied electromagnetic waves, causing electron cyclotron resonance, which ultimately absorbs the electromagnetic wave power, forming a plasma ECR surface (resonance point) at a location where the magnetic flux density is 875 G within the reduced-pressure vacuum vessel of the processing chamber 1, and the plasma expands and is generated over time.

[0031] The configuration of Example 2 will be described using Figures 1, 2, and 5. In Example 1, the cutoff waveguide 4 of the polarization combining antenna is directly connected to the circular waveguide 5, so in terms of the R-wave formation mechanism, at the connection with the circular waveguide 5, the evanescent fields excited from ports 1 and 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, it is possible to radiate the TE11 mode, in which the electric field rotates, from the circular waveguide 5. As can be seen in Figures 3B and 3C, the evanescent field excited in the cutoff waveguide 4 forms linearly polarized waves within the circular waveguide 5, so the connection between the cutoff waveguide 4 and the circular waveguide 5 does not necessarily have to be circular.

[0032] For this reason, in the second embodiment, the connection portion with the four-way cutoff waveguide 4 is formed as a rectangle for ease of manufacture, as shown in Fig. 5, and is connected to the circular waveguide 5. The microwaves propagating through the rectangular coupling portion 501 in Fig. 5 are in the TE10 mode, but this closely resembles the TE11 mode propagating through the circular waveguide 5 connected to the lower part of the rectangular coupling portion 501, so there is no unnecessary reflection. For this reason, even when the rectangular coupling portion 501 in Fig. 5 is provided, by controlling the phase of the solid-state microwave source 2 as in the first embodiment, it is possible to radiate circularly polarized waves, elliptically polarized waves, and microwaves with adjustable power to the processing chamber 1, as shown in Fig. 4.

[0033] In view of the above, since the coupled electric field due to the evanescent field forms linearly polarized waves in the ±Ex and ±Ey directions, the rectangular coupling portion 501 in FIG. 5 may have any shape as long as the linearly polarized waves can be propagated.

[0034] The configuration of Example 3 will be described using Figures 1 and 6. In conventional methods for radiating circularly polarized waves to a plasma processing apparatus, the incident and reflected waves are in the form of electromagnetic waves, so the circular polarizer has been designed for the configuration with the highest circular polarization axial ratio among the plasma processing conditions, or for each target process. As a result, there is no selectivity for the circular polarization that can be radiated, and the apparatus is generally designed to radiate R-wave circular polarization from the standpoints of ignition ability and plasma density. In contrast, the axial ratio of the circular polarization that can be provided by the plasma processing apparatus of this example is almost independent of the process conditions, and by controlling the output phase of the solid-state microwave source 2, R-wave, L-wave, and elliptical circular polarization can be selectively formed within the circular waveguide 5. By utilizing the above-described characteristics, Example 3 uses the phase controller 7 to control the output phase and ON / OFF combinations of the four solid-state microwave sources 2 during a certain time period t0, for example, as shown in Figure 6, and can radiate a wide variety of microwave radiation forms, including R-wave radiation, L-wave radiation, and elliptical circular polarization, at the desired timing.

[0035] Figure 7 shows the results of a simulation (using HFSS (High Frequency Simulation Software)) of the change in axial ratio within the circular waveguide due to differences in the reflection coefficient of the processing equipment for a comparative circularly polarized wave generator using a quarter-wave plate (see Figure 8) and the circularly polarized wave generator of this embodiment (see Figure 1). In this embodiment, the electromagnetic waves from the solid-state microwave source 2 are not directly emitted from the circular waveguide 5 of the polarization combining antenna, but the circularly polarized waves are indirectly introduced into the circular waveguide 5 by the evanescent field of the cutoff waveguide 4. Therefore, as shown in Figure 7, the reflected waves from the processing chamber 1 due to fluctuations in the plasma load caused by processing conditions such as the material gas G and pressure during the plasma etching process or film formation are less likely to be received, and a circularly polarized wave with a high axial ratio can be radiated into the processing chamber 1 even if the plasma load fluctuates. As shown in FIG. 7, in the configuration of this embodiment, unlike the conventional quarter-phase plate microwave plasma processing apparatus, reflected waves can be suppressed without providing the waveguide with a three-stub tuner, which is a reflected wave control device (reflected waves are in the form of electromagnetic waves and cannot pass through the cutoff waveguide 4), and circularly polarized waves with a high axial ratio can be radiated.

[0036] 4, it is possible to radiate not only circularly polarized waves but also elliptically polarized waves of different directions by controlling the output phase of the solid-state microwave source 2, and the form of polarization radiation can be selectively changed depending on the film distribution and etching rate on the substrate to be processed w. As mentioned above, the R-wave can continuously accelerate electrons in the direction of the magnetic field formed in the processing chamber 1, thereby obtaining a high plasma density. However, as the microwave supply power increases, the electron temperature Te increases, which causes negative charge to accumulate at the top end of the fin of the FinFET, and the electron shielding effect makes it difficult to precisely control the gate shape.

[0037] In contrast, with the plasma processing apparatus of this embodiment, the electron temperature Te can be controlled by selectively switching between R and L waves using the phase controller 7, making it possible to precisely process the gate shape of a semiconductor device. Furthermore, by selectively switching between R and L waves, the plasma absorption power of the entire plasma region formed in the processing chamber 1 or a specific region can be adjusted, making it possible to control not only a uniform etching rate for the substrate w to be processed, but also a desired etching rate distribution depending on the application, such as the temperature distribution of the substrate support. While an example of etching has been described here, the same applies to film formation.

[0038] The present invention is not limited to the above-described embodiments, but includes various modifications. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with other configurations.

[0039] 1...Processing chamber 2...Solid-state microwave source 3...Coaxial waveguide converter 4...Cutoff waveguide 5...Circular waveguide 6...Cavity 7...Phase controller 9...Upper electromagnetic coil 10...Middle electromagnetic coil 11...Lower electromagnetic coil 12...Yoke 13...Quartz window 14...Shower plate 15...Substrate to be processed stage 16...RF power supply 17...Vacuum pump w...Substrate to be processed G...Material gas 501...Rectangular coupling section.

Claims

1. A plasma processing apparatus comprising: a processing chamber for performing plasma processing; a circular waveguide connected to a cavity of the processing chamber and capable of propagating microwave power in TE11 mode; 2n solid-state microwave sources, where n is a natural number of 2 or more; a phase controller for controlling the phase of the microwave power output by each of the solid-state microwave sources; 2n coaxial-waveguide converters connected to each of the solid-state microwave sources and converting the microwave power from TEM mode to TE10 mode; and a polarization combining antenna having 2n cutoff waveguides connected to the circular waveguide on the same plane perpendicular to the axial direction of the circular waveguide, wherein the angle between adjacent cutoff waveguides in the axial direction is 180° / n, wherein the 2n cutoff waveguides are connected in a one-to-one relationship to the 2n coaxial-waveguide converters, and in the cutoff waveguides, the microwave power in TE10 mode is cut off and an evanescent field is excited toward the circular waveguide.

2. A plasma processing apparatus according to claim 1, wherein the evanescent field forms an electric field at a connection between the cutoff waveguide and the circular waveguide, and radiates microwave power in TE11 mode to the circular waveguide.

3. A plasma processing apparatus according to claim 1, wherein the 2n cutoff waveguides include a first cutoff waveguide and a second cutoff waveguide connected to the circular waveguide so as to face each other, the 2n solid-state microwave sources include a first solid-state microwave source and a second solid-state microwave source, and the phase controller causes the first solid-state microwave source connected to the first cutoff waveguide to generate microwaves that have an opposite phase to microwaves generated by the second solid-state microwave source connected to the second cutoff waveguide.

4. A plasma processing apparatus as claimed in claim 3, wherein n=2, the 2n cutoff waveguides include a third cutoff waveguide and a fourth cutoff waveguide connected to the circular waveguide so as to face each other, the 2n solid-state microwave sources include a third solid-state microwave source and a fourth solid-state microwave source, and the phase controller causes the third solid-state microwave source connected to the third cutoff waveguide to generate microwaves having a phase shift of 1 / 2π from the microwaves generated by the first solid-state microwave source, and causes the fourth solid-state microwave source connected to the fourth cutoff waveguide to generate microwaves having a phase shift of 4 / 2π from the microwaves generated by the first solid-state microwave source.

5. A plasma processing apparatus according to claim 1, wherein n=2, and the connection portion between the 2n cutoff waveguides and the circular waveguide in the polarized wave combining antenna is rectangular.

6. A plasma processing apparatus as claimed in claim 1, wherein the phase controller switches ON / OFF the phase of the microwaves generated by the 2n solid-state microwave sources and / or the output of the 2n solid-state microwave sources, thereby making it possible to switch the microwave radiation form of the microwaves propagating through the circular waveguide and radiated into the processing chamber.

7. A plasma processing apparatus as claimed in claim 6, wherein the phase controller switches ON / OFF the phases of the microwaves generated by the 2n solid-state microwave sources and / or the outputs of the 2n solid-state microwave sources, thereby coupling into the circular waveguide any of right-handed circularly polarized microwaves, left-handed circularly polarized microwaves, and elliptically polarized microwaves of a specified direction contained in the same plane perpendicular to the axial direction of the circular waveguide.

8. A plasma processing apparatus according to claim 7, wherein the microwave radiation form of the microwaves radiated into said processing chamber is switched during a plasma processing period in said processing chamber.

9. The plasma processing apparatus according to claim 8, wherein the plasma processing in the processing chamber is a plasma etching process or a film forming process.

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