Plasma treatment device

Abstract

A plasma processing device comprises: a vacuum chamber having a plasma processing chamber for performing plasma processing on a substrate and capable of exhausting the interior of the plasma processing chamber into a vacuum; and a microwave power supply unit for supplying microwave power to the vacuum chamber via a circular waveguide. In such a plasma processing device, the vacuum chamber comprises: a parallel plate line unit connected to the circular waveguide and receiving microwave power propagated from the circular waveguide; a ring resonator unit arranged on the periphery of the parallel plate line unit and receiving microwave power propagated from the parallel plate line unit; a cavity unit for receiving microwave power radiated from a slot antenna formed in the ring resonator unit; and a microwave introduction window separating the cavity unit and the plasma processing chamber, wherein the parallel plate line unit is configured to have a phase adjustment unit at a boundary portion with the ring resonator unit for adjusting the phase of microwaves propagated from the parallel plate line unit to the ring resonator unit.

Description

Technical Field

[0001] The present invention relates to a plasma processing device for generating plasma by electromagnetic waves. Background Art

[0002] Plasma processing equipment is used in the production of semiconductor integrated circuit components. The miniaturization of components is constantly being promoted in order to improve the performance of components and reduce costs. In the past, through the two-dimensional miniaturization of components, the number of components that can be manufactured from one processed substrate has increased, and the manufacturing cost of each component has been reduced. At the same time, there are effects such as shortening the wiring length, and performance can also be improved. However, if the size of the semiconductor component becomes nanometer-level, which is close to the size of an atom, the difficulty of two-dimensional miniaturization will increase significantly, and new materials and three-dimensional component structures are being used to deal with it. Through these structural changes, the difficulty of manufacturing increases, and the increase in manufacturing costs has become a serious problem.

[0003] If tiny foreign matter or contaminants are attached to semiconductor integrated circuit components during manufacturing, it will often become a fatal defect. Therefore, semiconductor integrated circuit components are mostly manufactured in a clean room where foreign matter and contaminants are removed and the temperature and humidity are controlled to the best. With the miniaturization of components, the cleanliness of the clean room required for manufacturing becomes higher, and huge costs are required in the construction and maintenance of the clean room. Therefore, it is sought to efficiently utilize the clean room space for production. From this point of view, semiconductor manufacturing equipment strictly pursues miniaturization and low cost.

[0004] In plasma processing devices that generate plasma by electromagnetic waves, devices that apply a static magnetic field to a plasma processing chamber are widely used. This is because, in addition to being able to suppress plasma loss by using a static magnetic field, there is also the advantage of being able to control the distribution of plasma. Furthermore, by using the interaction between electromagnetic waves and static magnetic fields, there is an effect that can be produced even under operating conditions where it is usually difficult to generate plasma. It is particularly known that if microwaves are used as electromagnetic waves for plasma generation, and a static magnetic field is used that makes the period of the cyclotron motion of electrons and the frequency of microwaves consistent, an electron cyclotron resonance (ECR) phenomenon will occur. Since plasma is mainly generated in the area that causes ECR, in addition to being able to control the plasma generation area by adjusting the distribution of the static magnetic field, there is also the effect of being able to more widely ensure the conditions for generating plasma through the ECR phenomenon.

[0005] RF bias technology is being used, in which high frequency is applied to the substrate being processed during plasma processing to attract ions in the plasma to the surface of the substrate being processed, thereby seeking to increase the speed of plasma processing and improve the processing quality. For example, in the case of plasma etching, since ions are vertically incident on the processed surface of the substrate being processed, anisotropic processing is achieved in which etching progresses only in the vertical direction of the substrate being processed.

[0006] As a conventional example corresponding to the above-mentioned problems and technical trends, in the plasma processing device described in Patent Document 1, an electromagnet for applying a static magnetic field around a processing chamber is provided, and a static magnetic field can be applied inside the processing chamber. Furthermore, the electromagnet is composed of a multi-stage electromagnet, and the static magnetic field distribution inside the processing chamber can be adjusted by adjusting the current value supplied to each electromagnet.

[0007] In Patent Document 1, microwaves with a frequency of 2.45 GHz are used as electromagnetic waves for plasma generation, which are circularly polarized by a circular polarization generator and provided to the device using a circular waveguide disposed on the central axis of the device. The output end of the circular waveguide is connected to a branch circuit, which is composed of a plurality of waveguides disposed at equal angles. In an embodiment, a square waveguide having four branches at equal angles every 90 degrees is used as a branch circuit. Furthermore, a ring resonator is excited in the plurality of waveguides of the branch circuit. A slit antenna is provided on the processing chamber side of the ring resonator, and microwaves are radiated from the slit antenna to the processing chamber in accordance with the electromagnetic field formed into a resonant mode in the ring resonator.

[0008] The static magnetic field in the processing chamber of Patent Document 1 is controlled to a desired distribution by the electromagnet, and interacts with the microwaves introduced to generate plasma in the processing chamber. The electromagnet can generate a static magnetic field that causes ECR in the processing chamber, and adjust the distribution to control the diffusion of plasma.

[0009] As described above, circularly polarized microwaves are introduced into the circular waveguide of Patent Document 1, thereby exciting traveling waves in the ring resonator. In the ring resonator, electromagnetic waves of multiple wavelengths are excited in one cycle in the azimuthal direction, but when a standing wave is excited, the unevenness in the azimuthal direction corresponding to the antinodes and nodes of the standing wave exists at fixed positions. By exciting traveling waves in the resonator, electromagnetic waves that are uniform in the azimuthal direction in terms of time are excited.

[0010] Prior art literature

[0011] Patent Literature

[0012] Patent Document 1: Japanese Patent Application Publication No. 2012-190899 Summary of the invention

[0013] Problems to be solved by the invention

[0014] Generally, plasma is lost at the wall surface of the plasma processing chamber, and the density tends to be low near the wall surface and high near the center away from the wall surface. As a result, the plasma density on the substrate being processed tends to be convexly distributed, and the uniformity of plasma processing sometimes becomes a problem.

[0015] Plasma has the property that it is easy to spread in the direction along the magnetic field lines, but its diffusion in the direction perpendicular to the magnetic field lines is suppressed. Furthermore, the position of the ECR surface can be adjusted to control the plasma generation area. In this way, the diffusion and generation area of ​​plasma can be adjusted by the static magnetic field, thereby adjusting the distribution of plasma.

[0016] However, there are cases where a desired adjustment range cannot be obtained only by means of adjusting the plasma density distribution based on the static magnetic field, and further additional adjustment means are desired.

[0017] For example, in the case of etching, the thickness of the film being processed may be thicker in the center of the substrate being processed and thinner on the periphery, or thinner in the center and thicker on the periphery, depending on the characteristics of the film forming device. There are cases where it is desired to correct the unevenness caused by these film forming devices in the etching process so as to perform uniform processing as a whole. In this way, there are cases where it is desired to adjust the plasma density distribution on the substrate being processed to a desired distribution.

[0018] Generally, if the etching rate is uniform, the reaction products are uniformly generated and released from all parts of the processed substrate. As a result, the density of the reaction products becomes higher in the center of the processed substrate, and lower in the periphery. If the reaction products reattach to the processed substrate, it will hinder the etching, thereby reducing the etching rate. The probability of the reaction products reattaching to the processed substrate is affected by many parameters such as the temperature of the processed substrate, the pressure of the processing chamber, and the surface state of the processed substrate. Therefore, in order to obtain uniform etching treatment within the surface of the processed substrate, there is a situation where the plasma density distribution on the processed substrate must be deliberately adjusted to be uneven.

[0019] As described above, a plasma processing apparatus that can easily control the plasma density distribution on a substrate to be processed is desired.

[0020] By using a ring resonator, an electromagnetic field distribution can be obtained that is low near the center and high near the periphery, and a plasma density distribution that is low at the center and high at the periphery can be obtained. If the plasma diffusion is taken into consideration, the density distribution that is too high near the center is likely to be obtained. In order to make a uniform plasma on the substrate to be processed, the plasma generation area must be adjusted to a density distribution that is low at the center and high at the periphery.

[0021] In Patent Document 1, a ring resonator is excited by waveguides arranged evenly in four azimuth directions. However, in this case, the unevenness of the electromagnetic field in the ring resonator caused by the connection parts of the waveguides at four locations and the unevenness of the plasma distribution caused by this may become significant. In addition, since the structure of the branches is complicated, the manufacturing cost and the difference between devices may become problems, and a simple excitation structure is desired.

[0022] The present invention solves the above-mentioned problems of the prior art and provides a plasma processing apparatus capable of uniformly exciting a ring resonator with a simple structure.

[0023] Means for solving problems

[0024] In order to solve the above-mentioned problems, in the present invention, a plasma processing apparatus comprises: a vacuum chamber having a plasma processing chamber for performing plasma processing on a substrate and capable of exhausting the interior of the plasma processing chamber into a vacuum; and a microwave power supply unit for supplying microwave power to the vacuum chamber via a circular waveguide. In the plasma processing apparatus, the vacuum chamber comprises: a parallel plate line unit connected to the circular waveguide and receiving microwave power propagated from the circular waveguide; a ring resonator unit arranged at the periphery of the parallel plate line unit and receiving microwave power propagated from the parallel plate line unit; a cavity unit for receiving microwave power radiated from a slot antenna formed in the ring resonator unit; and a microwave introduction window for separating the cavity unit from the plasma processing chamber, and the parallel plate line unit is provided with a phase adjustment unit for adjusting the phase of microwaves propagated from the parallel plate line unit to the ring resonator unit at a boundary portion with the ring resonator unit.

[0025] In addition, in order to solve the above-mentioned problems, the present invention is constituted by the following elements: a vacuum chamber having a plasma processing chamber for performing plasma processing on a substrate and capable of exhausting the interior of the plasma processing chamber into a vacuum; a circular waveguide which is arranged on the central axis of the vacuum chamber and has a circular cross section; a parallel plate line portion which is connected to the output end of the circular waveguide on one side of the vacuum chamber so that the propagation direction of microwave power propagated from the circular waveguide is perpendicular to the central axis of the vacuum chamber; a ring resonator portion which is connected to the outer periphery of the parallel plate line portion so that the microwave power propagated from the parallel plate line portion resonates with multiple wavelengths in the azimuth direction relative to the central axis of the vacuum chamber and a slit antenna is formed to radiate the resonated microwave power; a cavity portion which receives the microwave power radiated from the slit antenna formed in the ring resonator portion; and a microwave introduction window which separates the cavity portion from the plasma processing chamber.

[0026] Effects of the Invention

[0027] According to the present invention, since the electromagnetic field distribution in the ring resonator can be adjusted to a desired resonance mode with good accuracy using a simple structure, unnecessary electromagnetic field distribution that causes bias in plasma distribution can be suppressed, thereby allowing plasma processing with good uniformity to be performed on a substrate to be processed. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a side cross-sectional view illustrating a schematic structure of the microwave plasma etching device involved in Example 1.

[0029] Figure 2 The microwave plasma etching device according to the first embodiment Figure 1 AA section viewed from the direction of the arrow.

[0030] Figure 3A is a diagram showing a modification of the parallel plate circuit in the microwave plasma etching device according to the first embodiment. Figure 1 The cross-sectional view is taken in the direction of the arrow at section AA.

[0031] Figure 3B is a diagram showing another variation of the parallel plate circuit in the microwave plasma etching device according to the first embodiment. Figure 1 The cross-sectional view is taken in the direction of the arrow at section AA.

[0032] Figure 4 This is a cross-sectional view near the parallel plate circuit of the microwave plasma etching device of Example 2.

[0033] Figure 5 This is a cross-sectional view near the parallel plate circuit of the microwave plasma etching device of Example 3.

[0034] Fig. 6A This is a side cross-sectional view showing the schematic structure of the microwave plasma etching device of Example 4.

[0035] Figure 6B The microwave plasma etching device of Example 4 Fig. 6A BB section viewed in the direction of the arrow.

[0036] Figure 7 This is a longitudinal cross-sectional view near the circular waveguide of a microwave plasma etching device according to a variation of Example 4.

[0037] Figure 8 The microwave plasma etching device of Example 4 is equivalent to Fig. 6A The BB cross section of FIG. 1 is a top view of a conductor plate of a ring resonator according to a modification of the present embodiment, as viewed in the direction of arrows. DETAILED DESCRIPTION

[0038] In the present invention, in a plasma processing apparatus that generates plasma using electromagnetic waves, the distribution of plasma generated in a processing chamber is controlled by adjusting the distribution of microwave power, thereby enabling high-quality plasma processing.

[0039] In the present invention, in a microwave ECR plasma processing device, there is provided: a ring resonator that resonates in a mode having an electromagnetic wave corresponding to m wavelengths in the azimuth direction; a waveguide coaxially arranged with the central axis of the ring resonator; and a parallel plane line that transmits the electromagnetic wave transmitted from the waveguide to the ring resonator, thereby increasing the number of excitation points to uniformly excite the ring resonator, thereby improving the axial symmetry of the generated plasma and reducing microwave power loss. Furthermore, by simplifying the structure, the difference between devices (machine difference) can be reduced.

[0040] By using a ring resonator, the electromagnetic field distribution excited in the processing chamber can be adjusted to a ring-shaped distribution with a low center and a high periphery. Therefore, it is easy to generate plasma in a ring shape in the processing chamber. On the other hand, as mentioned above, due to the effect of plasma loss in the wall surface of the processing chamber and the effect of plasma diffusion, there is also a tendency that the plasma density near the wall surface is reduced and the density distribution near the center is high.

[0041] In contrast, in the present invention, the positional relationship between the ring plasma generation distribution based on the processing chamber wall and the ring resonator can be adjusted to obtain a uniform plasma distribution on the wafer. In addition, in the present invention, there are: a circular waveguide with a circular cross-section arranged on the central axis of a substantially axisymmetric plasma processing device; a plasma processing chamber for performing plasma processing on a substrate to be processed; a parallel plate line connected to the output end of the circular waveguide; a ring resonator in which the microwave propagation direction in the parallel plate line is perpendicular to the central axis and resonates with multiple wavelengths in the azimuth direction; an antenna for radiating electromagnetic waves in the ring resonator to the plasma processing chamber on the plasma processing chamber side of the ring resonator, the output end of the parallel plate line is connected to the ring resonator, and the ring resonator is excited evenly at the connection surface between the parallel plate line and the ring resonator, so that a uniform plasma distribution on the wafer can be obtained.

[0042] The embodiments of the present invention will be described in detail below based on the drawings. In all the drawings for describing the present embodiments, the same reference numerals are given to elements having the same functions, and their repeated descriptions are omitted in principle.

[0043] However, the present invention is not limited to the description of the following embodiments and will be interpreted. As long as a person skilled in the art can easily understand, the specific structure can be changed within the scope of the idea or purpose of the present invention.

[0044] Example 1

[0045] As an example of using the plasma processing apparatus of the present invention, by Figure 1 The microwave plasma etching apparatus 100 will be described.

[0046] Figure 1 FIG. 2 is a longitudinal sectional view showing the entire microwave plasma etching device 100. Figure 1 In the structure shown, 101 is a microwave oscillator (microwave power supply), 102 is an isolator, 103 is an automatic matcher, 1041 is a rectangular waveguide, 104 is a circular-rectangular converter, 105 is a circular polarization generator, 106 is a circular waveguide, 107 is a matching block, 108 is a parallel plate line, 109 is a phase adjustment unit, 110 is a ring resonator, 111 is a slot antenna, 112 is a cavity portion, 121 is an inner cavity portion, 126 is an inner cavity forming portion forming the inner cavity portion 121, 122 is an upper surface portion of the inner cavity forming portion 126, 123 is a side portion of the inner cavity forming portion 126, 124 is an inner edge portion of the inner cavity forming portion 126, and 125 is an outer edge portion of the inner cavity forming portion 126.

[0047] 113 is a static magnetic field generating device, 114 is a microwave introduction window, 115 is a shower plate, 116 is a plasma processing chamber, 117 is a processed substrate, 118 is a substrate electrode, 119 is an automatic matcher, 120 is an RF bias power supply, and 130 is a vacuum chamber.

[0048] exist Figure 1 In the structure shown, the following are omitted: a gas supply system for supplying gas to the plasma processing chamber 116; a vacuum exhaust unit for exhausting the interior of the plasma processing chamber 116 into a vacuum; a control unit for controlling the microwave oscillator 101, the automatic matcher 103, the static magnetic field generating device 113, the RF bias power supply 120, etc.

[0049] In the above structure, microwaves with a frequency of 2.45 GHz outputted from the microwave oscillator 101 are transmitted to the circular-rectangular converter 104 via the isolator 102 and the automatic matching device 103 through the rectangular waveguide 1041. A magnetron is used as the microwave oscillator 101. The circular-rectangular converter 104 also serves as a corner for turning the traveling direction of the microwave by 90 degrees, thereby miniaturizing the entire device.

[0050] A circular polarization generator 105 is connected to the lower part of the circular-rectangular converter 104 to convert the incident microwave with linear polarization into circular polarization. Furthermore, on one side of the plasma processing chamber 116 of the circular polarization generator 105, there is a circular waveguide 106 provided on the substantially central axis of the vacuum chamber 130 constituting the plasma processing chamber 116 to propagate the circularly polarized microwave.

[0051] The parallel plate line 108 formed by being sandwiched between the upper surface portion 122 of the inner cavity forming portion 126 and the upper surface of the vacuum chamber 130, i.e., the upper conductor 131, is connected to the end portion of the circular waveguide 106 via a matching block 107. The circular waveguide 106 and the parallel plate line 108 are orthogonal to each other, and the microwave power propagating from the circular waveguide 106 to the parallel plate line 108 changes its traveling direction.

[0052] The matching block 107 is a block made of metal with high conductivity that has a function of suppressing reflection of microwave power at a connection portion between the circular waveguide 106 and the parallel plate line 108 , and is formed into a conical shape in the present embodiment.

[0053] The parallel plate line 108 is connected to the ring resonator 110 on the upper side of the vacuum chamber 130, and provides the microwave power propagated from the circular waveguide 106 to the ring resonator 110, wherein the ring resonator 110 is formed by a space sandwiched by the side portion 123 of the inner cavity forming portion 126, the inner edge portion 124, and the outer edge portion 125.

[0054] In the parallel plate line 108, a phase adjustment unit 109 is installed near the boundary portion with the ring resonator 110. The phase adjustment unit 109 plays a role in reducing the mismatch of the microwave electromagnetic field distribution at the connection surface between the ring resonator 110 and the parallel plate line 108. By reducing the mismatch of the microwave electromagnetic field distribution at the connection surface between the ring resonator 110 and the parallel plate line 108 by the phase adjustment unit 109, a desired resonance mode can be excited in the ring resonator 110.

[0055] In this embodiment, a dielectric block is used as the phase adjustment unit 109. The phase adjustment unit 109 is not limited thereto, and other structures may be used, such as a structure in which a protruding stub, a groove, or a linear protrusion is provided on the inner surface of the parallel plate line 108.

[0056] A slot antenna 111 is provided as a microwave radiating unit at the bottom of the ring resonator 110, and a cavity 112 is provided at the bottom of the slot antenna 111. The slot antenna 111 is formed by a space sandwiched between the outer peripheral surface of the inner edge 124 of the inner cavity forming portion 126 and the inner peripheral surface of the outer edge 125.

[0057] The microwaves having an electromagnetic field distribution are excited in a desired resonance mode inside the ring resonator 110 and radiated from the slot antenna 111 to the lower cavity 112. An inner cavity 121 formed by the upper surface 122 and the side surface 123 of the inner cavity forming portion 126 is provided inside the ring resonator 110, and together with the cavity 112, it has a function of adjusting the electromagnetic field distribution of the microwaves radiated from the slot antenna 111.

[0058] The lower part of the cavity 112 is divided into a plasma processing chamber 116 by a microwave introduction window 114 and a shower plate 115. The microwave introduction window 114 and the shower plate 115 are made of quartz, which is a material with little microwave loss and is unlikely to adversely affect plasma processing, such as the generation of foreign matter.

[0059] The inner cavity 121 inside the ring resonator 110 has a function of adjusting the electromagnetic field distribution of the microwave radiated from the slot antenna 111 together with the cavity 112. A plasma processing chamber 116 is provided below the shower plate 115, and plasma is generated by the radiated microwave power.

[0060] The plasma processing chamber 116 is connected to a gas supply system (not shown) and a vacuum exhaust system (not shown) and is controlled to a gas atmosphere and pressure suitable for plasma processing. The plasma processing chamber 116 and the cavity 112 are divided by a microwave introduction window 114, and one side of the cavity 112 is in an atmospheric pressure state, and one side of the plasma processing chamber 116 exhausts the interior and maintains a vacuum state.

[0061] The processing gas is supplied from a gas supply system (not shown) to a fine gap (not shown) between the microwave introduction window 114 and the shower plate 115 , and is supplied into the plasma processing chamber 116 through a plurality of fine supply holes (not shown) provided in the shower plate 115 .

[0062] A substrate electrode 118 for placing a substrate 117 to be processed is provided in the plasma processing chamber 116 in an electrically insulated state. An RF bias power supply 120 is connected to the substrate electrode 118 via an automatic matching device 119 so that an RF bias can be applied to the substrate 117 to be processed.

[0063] A static magnetic field generator 113 for applying a static magnetic field is provided around the plasma processing chamber 116. In the present embodiment, the static magnetic field generator 113 is composed of a multi-stage solenoid coil, and the distribution of the static magnetic field applied to the plasma processing chamber 116 can be adjusted by adjusting the DC current supplied by a plurality of DC power supplies (not shown). As a unit for generating a static magnetic field instead of the static magnetic field generator 113 or as a unit for generating a static magnetic field together with the static magnetic field generator 113, a permanent magnet or a magnetic body can be used in combination.

[0064] exist Figure 2 Show Figure 1 The AA cross-section in the figure is viewed in the direction of the arrow, i.e., a cross-sectional view of the vicinity of the parallel flat line 108. As described above, a dielectric block is installed in the parallel flat line 108 as a phase adjustment unit 109. In Patent Document 1, the ring resonator is excited by four square waveguides, but in this embodiment, as shown in FIG. Figure 2As shown in FIG. 1 , the parallel plate circuit 108 having a phase adjustment unit 109 is used for excitation. Figure 2 In the illustrated structure, four phase adjustment units 109 are arranged at equal intervals, and the width of each of the four phase adjustment units 109 in the circumferential direction is formed to be the same size as the width of the interval between adjacent phase adjustment units 109 .

[0065] The electromagnetic field in the ring resonator 110 is the same as described in Patent Document 1, and uses a mode that resonates in the azimuth direction by an amount corresponding to 5 wavelengths (hereinafter referred to as TM51 mode). In addition, the circular waveguide 106 on the central axis is also the same as described in Patent Document 1, and uses the lowest-order mode TE11 mode. The TE11 mode changes phase by 360 degrees in one cycle, 360 degrees, in the azimuth direction. In the TM51 mode of the ring resonator, the phase changes by 360 degrees × 5 wavelengths in one cycle, 360 degrees, in the azimuth direction. Therefore, as described in Patent Document 1 Figure 5 As described, the phases of electromagnetic waves of the TE11 mode and the TM51 mode are aligned at four locations every 90 degrees, and the ring resonator is excited using these four locations.

[0066] In contrast, in this embodiment, the four connecting portions ( Figure 2 In the regions 201, 202, 203, 204 sandwiched by adjacent phase adjustment units 109, the phases of the TE11 mode and the TM51 mode are consistent.

[0067] On the other hand, four dielectric blocks are used as the phase adjustment unit 109, but it is known that the wavelength of electromagnetic waves is generally shortened to 1 / n of the length in a material with a refractive index of n compared to a vacuum or the atmosphere. In this embodiment, quartz is used as the material of the four dielectric blocks as the phase adjustment unit 109. It is known that the refractive index of quartz is about 2, and the wavelength of electromagnetic waves in quartz is shortened to about half.

[0068] The microwaves propagating through the parallel plate line 108 are also shortened in wavelength in the dielectric block serving as the phase adjustment unit 109, and their phases are changed compared to the microwaves that have not passed through the dielectric block. By adjusting the amount of phase change, the connection surface (at the junction of the ring resonator 110 and the parallel plate line 108) between the ring resonator 110 and the parallel plate line 108 is Figure 2 The electromagnetic waves of the TM51 mode and the TE11 mode are roughly consistent, and the TM51 mode of the ring resonator can be excited with good accuracy. In this case, it is equivalent to aligning the phases of the TE11 mode and the TM51 mode at 8 locations, including the 4 connecting locations that include the phase adjustment unit 109, in addition to the 4 connecting locations that do not include the phase adjustment unit 109.

[0069] If the phases are to be aligned at the same eight locations in the waveguide described in Patent Document 1, it is necessary to use eight branched waveguides to adjust the phases respectively, which has the disadvantage of making the structure complicated. In addition, in the method of exciting through four waveguides in Patent Document 1, as described above, there is a disadvantage that the deviation from the desired TM51 mode becomes larger due to unevenness caused by the waveguide connection.

[0070] In contrast, when using Figure 2 In the present embodiment described, an example in which the slot antenna 111 is formed in a circular shape in the azimuth direction is described, but the slot antenna 111 may be replaced with a circular ring. Figure 3A The slot antenna 301 shown in the figure is formed in large numbers radially on the inner edge 124 and the outer edge 125 of the inner cavity forming portion 126, or Figure 3B Antennas of other shapes such as a plurality of arc-shaped slot antennas 302 formed on a plurality of concentric circles at the inner edge 124 and the outer edge 125 of the inner cavity forming portion 126 as shown.

[0071] According to the present embodiment, since the number of excitation points is increased, the inside of the ring resonator 110 can be resonated more evenly, and thus the axial symmetry of the generated plasma can be improved.

[0072] In addition, according to this embodiment, by simplifying the branching structure to a plurality of waveguides described in Patent Document 1 into a parallel plate line 108, it is possible to reduce the loss of microwave power, and to reduce manufacturing costs and differences between devices.

[0073] Furthermore, according to the present embodiment, the ring resonator 110 is excited uniformly at the connection surface between the parallel planar line 108 and the ring resonator 110 , thereby performing uniform excitation of the electromagnetic field distribution within the ring resonator 110 .

[0074] Furthermore, according to this embodiment, by providing phase adjustment unit 109 in parallel plate line 108 , the resonant electromagnetic field in ring resonator 110 and the electromagnetic field at the connection surface with parallel plate line 108 can be made to match with higher accuracy, thereby uniformly exciting ring resonator 110 .

[0075] Furthermore, according to this embodiment, circular polarization is input into the circular waveguide 106 using the circular polarization generator 105 to excite a traveling wave in the ring resonator 110, thereby suppressing the generation of standing waves in the ring resonator 110 and enabling uniform plasma generation.

[0076] Furthermore, according to the present embodiment, by performing phase adjustment by the phase adjustment unit in detail, even when linear polarization is input into the circular waveguide, a traveling wave can be excited in the ring resonator.

[0077] Example 2

[0078] As a second embodiment, as equivalent to Figure 1 AA section arrow direction observation diagram Figure 4 , showing a cross-sectional view of the vicinity of the parallel plate line 108 in which a ridge 401 is added in addition to the phase adjustment unit 109. Figure 1 The first embodiment shown is the same, so the instrument uses Figure 4 Explain the differences.

[0079] exist Figure 4 In the structure near the parallel plate line 108 according to the present embodiment shown, a ridge 401 is added adjacent to each phase adjustment unit 109. The ridge 401 is composed of a conductive column connecting the upper surface portion 122 of the inner cavity forming portion 126 forming the parallel plate line 108 and the upper surface of the vacuum chamber 130, that is, the upper conductor 131.

[0080] If used as a slot antenna, use Figure 2 The annular slot antenna 111 formed between the inner edge 124 of the inner cavity forming portion 126 and the outer edge 125 of the inner cavity forming portion 126 as shown in the figure has the following structure: the inner conductor plate of the slot antenna 111, i.e., the inner edge 124 of the inner cavity forming portion 126, and the outer conductor plate, i.e., the outer edge 125, do not contact each other, and the lower conductor of the parallel plate line 108, i.e., the upper surface portion 122, is fixed to the upper conductor only by the phase adjustment unit 109. By using the ridge 401, the upper and lower conductor plates of the parallel plate line 108 can be stably held.

[0081] Generally, traveling waves can be excited by exciting positions with a path length difference of 1 / 4 wavelength in the waveguide with a phase difference of 90 degrees. Consider the case where this method is used to excite traveling waves in a ring resonator that resonates in a mode corresponding to 5 wavelengths in the azimuth direction, for example, by using a circular waveguide of the TE11 mode provided on the central axis of the ring resonator.

[0082] The azimuth angle difference equivalent to 1 / 4 wavelength in the ring resonator becomes 18 degrees. Since the TE11 mode of the circular waveguide is a mode that shows a 360-degree phase change corresponding to 1 wavelength in the azimuth direction of the waveguide cross section, the phase difference of the TE11 mode of the circular waveguide becomes 18 degrees relative to the azimuth angle difference of 18 degrees. In order to have a 90-degree phase difference in the excitation source with a phase difference of 18 degrees, a phase difference of 72 degrees can be given as a subtraction. A dielectric having a wavelength shortening effect can be used to give this 72-degree phase difference. It can be seen that by giving a 72-degree phase difference every time the azimuth angle increases by 18 degrees, a traveling wave can be excited in the ring resonator.

[0083] According to this embodiment, in addition to the effects described in the first embodiment, by providing a structure using ridges 401 for short-circuiting between conductor plates in parallel plate line 108, parallel plate line 108 can be stably maintained and ring resonator 110 can be uniformly excited.

[0084] Example 3

[0085] As a third embodiment, Figure 5 Only the equivalent Figure 1 The cross-sectional view of the parallel plate circuit 108 is viewed in the direction of the arrow AA in the figure. Figure 5 To illustrate only Figure 1 , 2 The differences from the first embodiment shown.

[0086] As described above, by exciting multiple positions of the ring resonator 110 with a given phase difference, a traveling wave can be excited in the ring resonator L10. In the first and second embodiments, the phase adjustment unit 109 is composed of four dielectric blocks. In contrast, in this embodiment, as the phase adjustment unit 510, Figure 5 As shown, a disk-shaped dielectric having an opening 501 of a special shape inside is used.

[0087] As described above, the wavelength of the electromagnetic wave propagating in the dielectric is shortened according to the refractive index, and the phase is changed according to the path length. The phase adjustment unit 510 involved in this embodiment is set to a hole shape in which the radius from the center of the end face decreases monotonically as the azimuth angle increases, as shown in 511, when the azimuth angle is greater than 0 degrees and less than 90 degrees. Similarly, the hole shape is also set to be a hole shape in which the radius from the center of each end face decreases monotonically as the azimuth angle increases, as shown in 512, 513, and 514, when the azimuth angle is greater than 90 degrees and less than 180 degrees, greater than 180 degrees and less than 270 degrees, and greater than 270 degrees and less than 360 degrees. In addition, the end faces 511, 512, 513, and 514 are formed so that the radius of the position where the azimuth angle is 90 degrees away is the same.

[0088] The microwave excited in the TE11 mode of the circular waveguide 106 and propagating in all azimuth directions of the parallel plate line 108 is phase-controlled by the phase adjustment unit 510 of the above shape and reaches the connection surface with the ring resonator 110. By adjusting the degree of monotonous decrease of the radius, the phase accuracy at the connection surface can be well approximated to the traveling wave corresponding to the TM51 mode of the ring resonator 110. Thus, the traveling wave can be excited in the ring resonator 110. In this case, the circular polarization generator 105 loaded in the circular waveguide 106 can be omitted. In addition, by using the circular polarization generator 105 in combination instead of omitting it, the traveling wave can be generated in a wider range of plasma generation conditions.

[0089] According to this embodiment, the same effects as those described in Embodiment 1 can be obtained. In the above, a ring resonator that resonates in a mode corresponding to five wavelengths in the azimuth direction is described as an example, but a ring resonator that resonates in another resonance mode may also be used.

[0090] Example 4

[0091] As a fourth embodiment, a microwave plasma etching device 600 having a structure in which a conductor plate for removing an unnecessary mode electric field is inserted into the ring resonator 110 is used. FIG. 6A to FIG. 8 , only explains Figure 1 , 2 The differences from the first embodiment described in .

[0092] In this embodiment, FIG. 6A to FIG. 8 The microwave plasma etching device 600 shown in the embodiment 1 is Figures 1 to 3B The same elements as those in the microwave plasma etching apparatus 100 described above are denoted by the same reference numerals, and their description is omitted. Fig. 6A In the microwave plasma etching device 600 shown in FIG. Figure 1 The microwave plasma etching apparatus 100 also omits the exhaust system.

[0093] When the microwave plasma etching apparatus 100 having the structure described in the first embodiment is used to perform experiments by changing the plasma generation conditions such as pressure and microwave power, the etching rate distribution on the wafer may be non-axisymmetric. If the cause is studied, it can be found that the electromagnetic field distribution in the ring resonator contains an unnecessary mode in addition to the desired mode.

[0094] Therefore, the structure of suppressing unnecessary modes was studied, and the resulting structure was Fig. 6A , Figure 6B Shown. Fig. 6A1 is a side cross-sectional view showing a schematic structure of a microwave plasma etching device 600 according to the present embodiment. Figure 6B express Fig. 6A BB section viewed in the direction of the arrow.

[0095] The microwave plasma etching device 600 in this embodiment is characterized by the following structure: Figure 1 A plurality of plates 601 formed of conductor plates for removing an unnecessary mode electric field are radially filled in the ring resonator 110 of the microwave plasma etching device 100 at equal intervals. Fig. 6A As shown, the ring resonator 110 is divided into two parts, an upper resonant chamber 1101 and a lower resonant chamber 1102 , by a plate 601 which is a conductive plate.

[0096] Will Fig. 6A The height direction is set to the thickness of the plate 601. Figure 6B As shown, the plates 601 are arranged radially and evenly spaced relative to the central axis of the ring resonator 110 , and the upper resonant chamber 1101 and the lower resonant chamber 1102 are connected between adjacent plates 601 .

[0097] In addition, the plate 601 as the conductor plate is made of aluminum as a high-conductivity material with low microwave loss. The surface can be plated with silver or gold with high conductivity to further reduce the loss.

[0098] It is known that, generally, if an ideal conductor is placed in an electromagnetic field, the electric field component is perpendicular to the ideal conductor surface. That is, when the ideal conductor surface is placed perpendicular to the original electric field distribution, the original electric field distribution will not be affected. On the other hand, when there is an electric field component parallel to the ideal conductor surface, the electric field component parallel to the surface becomes zero because the electric field component is short-circuited on the surface of the ideal conductor, thereby changing the original electric field distribution.

[0099] By utilizing this property to load an ideal conductor plate perpendicularly to the electric field for a desired electromagnetic field distribution, it is possible to suppress a mode having an electric field component parallel to the ideal conductor plate without affecting the desired electromagnetic field distribution.

[0100] In the case of this embodiment, the electric field of the desired mode inside the ring resonator 110 is Fig. 6A The electric field has only a component in the longitudinal direction. Therefore, if an ideal conductor plate having a surface perpendicular to the ideal conductor plate is loaded into the ring resonator 110, the mode having a component parallel to the surface of the ideal conductor plate can be suppressed (reduced) without affecting the desired mode. The ideal conductor plate is simulated by a high-conductivity material. The higher the conductivity of the material used, the lower the power loss for the desired mode.

[0101] It is also known that under high frequencies such as microwaves, electromagnetic fields cannot penetrate into the interior of materials with high conductivity, and electromagnetic fields exist only on the surface, which is called the skin effect. Therefore, the conductivity of the surface of the plate 601 as a conductor plate is important, and means such as coating only the surface of the plate 601 with a material with high conductivity can be used.

[0102] That is, in this modification, the high-conductivity material made of aluminum is used to form Fig. 6A The plate 601 as a conductor plate in the microwave plasma etching device 600 shown in FIG. Figure 6B As shown in the figure, a structure is set to be arranged with multiple pieces at equal intervals. By setting such a structure, the microwave radiated from the slot antenna 111 at the bottom of the ring resonator 110 to the cavity 112 can be a desired mode. As a result, by generating plasma with a desired distribution inside the plasma processing chamber 116, the uniformity of plasma processing on the substrate 117 to be processed can be improved.

[0103] By setting the microwave plasma etching device 600 to the structure shown in this embodiment, when the microwave power supplied to the ring resonator 110 by the microwave power source 101 oscillating and propagating in the parallel plate line 108 resonates between the upper resonant chamber 1101 and the lower resonant chamber 1102 of the ring resonator 110, the electric field component having a component parallel to the surface of the plate 601 is short-circuited and extinguished on the surface of the plate 601. As a result, the microwave resonating inside the ring resonator 110 becomes a desired mode having mainly an electric field component perpendicular to the plate 601.

[0104] In a state where such an electric field of a desired mode is formed in the ring resonator 110 , microwaves are radiated toward the cavity 112 from the annular slot antenna 111 formed at the lower portion of the ring resonator 110 as described in the first embodiment.

[0105] Alternatively, the slit antenna 111 of the ring resonator 110 may be replaced by using Figure 3A The slot antenna 301 shown or Figure 3B The slot antenna 302 is shown.

[0106] In addition, the structure of the parallel plate line 108 may be the same as that described in the second embodiment. Figure 4 The phase adjustment unit 109 shown in the figure has a structure in which the ridge 401 is added, or the phase adjustment unit 109 is replaced with the structure used in the third embodiment. Figure 5 The structure of the phase adjustment unit 510 is described.

[0107] Here, generally, if there is a discontinuous portion in the transmission path of the microwave, a reflected wave will be generated at the location, thereby reducing the transmitted power. In the microwave plasma etching device 600 of the present embodiment, ideally, it is desired to eliminate the discontinuous portion as much as possible in the transmission path of the microwave power from the microwave power source 101 to the load, that is, the plasma processing chamber 116 forming the plasma generation area, to transmit the microwave power.

[0108] However, there are cases where a discontinuity must be formed for the purpose of controlling the electromagnetic field distribution, such as the plate 601 installed inside the ring resonator 110. When such a discontinuity is provided in the microwave transmission path, there is a concern that the transmission power may be reduced due to the discontinuity. In particular, in the case of a complex structure such as the present embodiment, it becomes important to suppress reflected waves.

[0109] In the suppression of reflected waves, it is effective to cancel the reflected waves by superimposing waves with the same amplitude but inverted phase on the reflected waves, and various structures have been put into practical use. For example, a three-stub matching device is often used in the suppression of reflected waves in a square waveguide system. Three conductor rods called stubs with variable insertion lengths are set in the square waveguide, and the original reflected waves can be canceled by adjusting the insertion length of each stub.

[0110] In this embodiment, when there is a concern about the increase of reflected waves due to the filling plate 601 inside the ring resonator 110, a discontinuous portion for canceling the reflected waves is provided in the waveguide, thereby effectively suppressing the reflected waves. Figure 7 An example in which a discontinuous portion 701 is provided in the middle of the circular waveguide 106 is shown.

[0111] As described in Example 1, the electromagnetic wave propagating in the circular waveguide 106 is circularly polarized by the circular polarization generator 105. The discontinuous portion 701 according to this example is provided in the middle of the circular waveguide 106 and is composed of a circular waveguide having an inner diameter larger than that of the circular waveguide 106.

[0112] By adjusting the inner diameter and length of the discontinuous portion 701 formed by the circular waveguide and the connection position with the circular waveguide 106, the magnitude and phase of the reflected wave generated by the discontinuous portion 701 can be adjusted, thereby canceling the reflected wave caused by the plate 601. In addition, the reflected wave caused by the structure other than the plate 601 (for example, the reflected wave generated by the phase adjustment unit 109) can also be included and canceled.

[0113] The discontinuous portion 701 needs to be a structure without asymmetry so as not to hinder the circular polarization propagating inside the circular waveguide 106. In this embodiment, it is a circular waveguide with a larger inner diameter than the circular waveguide 106. As another structure, a circular waveguide with a smaller inner diameter than the circular waveguide 106 may also be used.

[0114] exist Figure 8 The microwave plasma etching device in this embodiment is equivalent to Fig. 6A A top view of a modified example of the conductor plate of the ring resonator as viewed in the direction of the arrow in the BB cross section. Fig. 6A as well as Figure 6B Elements with the same structure as described in the above are marked with the same part numbers and the description is omitted. Figure 6B The conductor plate 601 described in the specification, but in Figure 8 In order to facilitate understanding of the structure of the plurality of slits 611 and 612, the Figure 6B A display of a conductor plate 601 is illustrated in FIG.

[0115] exist Figure 8 In the present modification shown, Figure 6B The inner edge 124 and the outer edge 125 of the inner cavity forming portion 126 of the ring resonator 110 described in the above are formed with a lower surface portion 610. In this modified example, the lower surface portion 610 is formed by a plurality of inner slits 611 and outer slits 612. Figure 6B A circular ring-shaped slot antenna 111 is formed at the lower portion of the ring resonator 110 described in the figure.

[0116] In this way, it is also possible to replace Figure 6B The circular slot antenna 111 described in Figure 8 As shown, there are multiple inner slits 611 and outer slits 612.

[0117] According to this embodiment, since microwaves formed by an electric field of a desired mode can be radiated from the slot antenna 111 to the cavity portion 112, axially symmetrical plasma can be generated inside the plasma processing chamber 116. Compared with the case where multiple plates 601 are not loaded inside the ring resonator 110, the uniformity of processing the processed substrate 117 can be improved.

[0118] In addition, by providing a discontinuous portion 701 in the circular waveguide 106 connected to the parallel plate line 108 to reduce the structure of the reflected waves caused by the plate 601, the reduction in transmission power due to the reflected waves can be prevented, and the energy efficiency can be prevented from being reduced by filling the plate 601 inside the ring resonator 110.

[0119] In addition, the discontinuous portion 701 described in this embodiment can also be applied to the Figure 1 In this case, the microwave plasma etching device 100 is Figure 1 In the structure shown, a discontinuous portion 701 is installed in the middle portion of the circular waveguide 106. This can reduce the reflected waves generated by the phase adjustment unit 109 and the like.

[0120] The invention made by the inventor is specifically described above based on the embodiments, but the present invention is not limited to the embodiments, and various changes can be made within the scope of the gist. This is self-evident. For example, the above embodiments are described in detail to explain the present invention in an easy-to-understand manner, but are not necessarily limited to all the structures described. In addition, other structures can be added, deleted, or replaced with a part of the structure of each embodiment.

[0121] Description of Reference Numerals

[0122] 100 Microwave plasma etching device

[0123] 101 Microwave Oscillator

[0124] 102 Isolator

[0125] 103 Automatic Matcher

[0126] 104 Circular-rectangular converter

[0127] 105 Circular Polarization Generator

[0128] 106 Circular waveguide

[0129] 107 Matching Block

[0130] 108 Parallel Plate Circuit

[0131] 109 Phase adjustment unit

[0132] 110 Ring Resonator

[0133] 111 Slot Antenna

[0134] 112 Hollow

[0135] 113 Static Magnetic Field Generator

[0136] 114 Microwave introduction window

[0137] 115 Shower Panel

[0138] 116 Plasma treatment chamber

[0139] 117 Processed substrate

[0140] 118 substrate electrode

[0141] 121 Inner cavity

[0142] 130 Vacuum Chamber

[0143] 301 Radiating Slot Antenna

[0144] 302 Arc-shaped slot antenna

[0145] 401 Ridge

[0146] 510 Phase Adjustment Unit

[0147] 601 Board

[0148] 701 Discontinuity.

Claims

1. A plasma processing device, characterized in that: have: a processing chamber that performs plasma treatment on the sample; a high-frequency power source that supplies high-frequency power of microwaves for generating plasma; A ring resonator that resonates the propagating microwaves so that, when m is an integer greater than or equal to 2, the mode of the microwaves propagating through a circular waveguide having a circular cross section becomes a mode of microwaves having m wavelengths in an azimuth direction; and a dielectric window disposed above the processing chamber to allow the propagated microwave to pass through the processing chamber, The circular waveguide propagates the microwave to the ring resonator via the parallel plate line portion. The parallel plate line section includes a phase adjuster whose upper and lower surfaces are circular and which adjusts the phase of the microwave propagating toward the ring resonator to a predetermined phase. The ring resonator includes a plurality of conductor plates arranged along a circumferential direction.

2. A plasma processing device, characterized in that: have: a processing chamber that performs plasma treatment on the sample; a high-frequency power source that supplies high-frequency power of microwaves for generating plasma; A ring resonator that resonates the propagating microwaves so that, when m is an integer greater than or equal to 2, the mode of the microwaves propagating through a circular waveguide having a circular cross section becomes a mode of microwaves having m wavelengths in an azimuth direction; and a dielectric window disposed above the processing chamber to allow the propagated microwave to pass through the processing chamber, The circular waveguide propagates the microwave to the ring resonator via the parallel plate line portion. The parallel plate line section includes a phase adjuster whose upper and lower surfaces are circular and which adjusts the phase of the microwave propagating toward the ring resonator to a predetermined phase. The ring resonator includes: a plurality of plates arranged so that the surfaces are perpendicular to the electric field of the mode having the m wavelengths of microwaves in the azimuth direction; The material of the plate is a material of a given electrical conductivity.

3. The plasma processing device according to claim 1 or 2, characterized in that: The parallel plate circuit portion is one, The phase adjuster is formed of a dielectric.

4. The plasma processing device according to claim 1 or 2, characterized in that: The phase adjuster is disposed at a connection portion between the parallel plate line portion and the ring resonator.

5. The plasma processing device according to claim 4, characterized in that: The number of the phase adjusters is 4.

6. The plasma processing device according to claim 1 or 2, characterized in that: The parallel plate line section includes a metal matching member that suppresses reflection of the microwave propagating from the circular waveguide.

7. The plasma processing device according to claim 1 or 2, characterized in that: A slot antenna having an opening portion for radiating the microwave resonated by the ring resonator is formed in the ring resonator.

8. The plasma processing device according to claim 7, characterized in that: The opening is a circular ring-shaped opening.

9. The plasma processing device according to claim 7, characterized in that: The openings are a plurality of openings arranged radially.

10. The plasma processing device according to claim 7, characterized in that: The openings are a plurality of arc-shaped openings arranged in the circumferential direction.

11. The plasma processing device according to claim 1 or 2, characterized in that: A conductive post for short-circuiting the upper surface of the parallel plate line portion and the lower surface of the parallel plate line portion is disposed next to the phase adjuster.

12. The plasma processing device according to claim 1 or 2, characterized in that: The predetermined phase is a phase that reduces mismatching of electromagnetic field distribution of the microwave at a connection surface between the ring resonator and the parallel plate line portion.

13. The plasma processing device according to claim 5, characterized in that: The plasma processing device further comprises: A magnetic field forming mechanism forms a magnetic field in the processing chamber.

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