JP2010277971A - Plasma processing device and power feeding method for the plasma processing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To supply microwaves to a treatment chamber from an electrode disposed at a desired position in a desired shape using a rectangular waveguide for a transmission line. <P>SOLUTION: A microwave plasma processing drive 100 includes microwave sources 40 which output the microwaves, a power feeding waveguide 30 coupled to the microwave sources, a plurality of reflecting waveguides 31 each of which is coupled to the power feeding waveguide 30 and has an inner space communicating with the inner space of the power feeding waveguide 30, and a plurality of metal slot antennas 32 each of which is provided adjacent to the reflecting waveguide 31 and has a slot group 32ag, including two or more reflecting slots 32a, formed at equal intervals for every multiple of the in-tube wavelength λg/2 of the microwaves transmitted through the reflecting waveguide 31. The plasma processing device also supplies the microwaves transmitted from the power feeding waveguide 30 to the plurality of the reflecting waveguides 31 into the treatment chamber through the slot groups 32ag, and propagates them along metal surfaces of the slot antennas 32 forming the inner wall of the treatment chamber. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a transmission line for supplying electromagnetic waves to a plasma processing apparatus and a power feeding method using the transmission line.

  A transmission line for transmitting electromagnetic waves such as microwaves is assembled outside the plasma processing apparatus. The transmission line connects the electromagnetic wave source and the plasma processing apparatus. The electromagnetic wave output from the electromagnetic wave source is transmitted through the transmission line and supplied into the processing chamber from the electrode provided in the plasma processing apparatus. The supplied microwave becomes a surface wave and propagates through the boundary between the inner surface of the processing chamber and the plasma, and a part of the energy is used for plasma generation during the propagation.

  For the transmission line, a coaxial waveguide and a rectangular waveguide are mainly used. In Patent Document 1, a coaxial waveguide is used as a transmission line.

JP 2008-305736 A

  However, in the case of feeding by a coaxial waveguide, the design of the manufacturing size greatly affects the transmission performance as compared with the rectangular waveguide. As shown in FIG. 11, when a transmission line is configured by connecting a plurality of coaxial waveguides 90, it is necessary to design a large number of branch circuits 90a in the transmission line according to the substrate size (the size of the chamber 92). In the first place, the design is difficult, and the influence of the design tolerance on the transmission performance becomes large.

  As a result, the impedance adjustment of the coaxial waveguide line becomes complicated, and when the electromagnetic wave is transmitted while being branched in many ways and supplied from the respective electrodes 94 to the processing chamber, the electric field strength of the electromagnetic waves supplied to the respective electrodes 94 is not good. It becomes uniform and the uniform generation of plasma is prevented. Further, in the coaxial waveguide, since the configuration of the entire transmission line is complicated as shown in FIG. 11, not only manufacturing and assembly, but also maintenance is required, and the cost is increased.

  In order to solve the above problems, the present invention provides a plasma processing apparatus for supplying electromagnetic waves to a processing chamber by using a power feeding waveguide and a radiation waveguide for a transmission line, and a plasma processing apparatus using the transmission line. Provide a method for supplying power to

  That is, in order to solve the above-described problem, according to an aspect of the present invention, there is provided a plasma processing apparatus that generates plasma by exciting a gas by energy of electromagnetic waves and performs plasma processing on an object to be processed in a processing chamber. An electromagnetic wave source for outputting an electromagnetic wave, a power supply waveguide connected to the electromagnetic wave source, and a plurality of internal spaces connected to the internal space of the power supply waveguide connected to the power supply waveguide And an in-tube wavelength λg / 2 of an electromagnetic wave that is provided adjacent to the plurality of radiation waveguides and includes a group of two or more radiation slots and that transmits the radiation waveguide. A plurality of metal slot antennas formed at equal intervals every integer multiple of, and electromagnetic waves transmitted from the feeding waveguide to the plurality of radiating waveguides are formed at the same intervals. Through the slots and into the process chamber Feeding to said processing chamber said plasma processing apparatus to propagate along the metal surface of the slot antenna for forming the inner wall is provided.

  According to such a configuration, the electromagnetic wave transmitted through the feeding waveguide is distributed to each of the plurality of radiating waveguides and transmitted through the radiating waveguides. It is passed through a slot group formed at equal intervals every integral multiple of λg / 2 and supplied to the processing chamber. The supplied electromagnetic wave propagates as a surface wave on the boundary surface between the metal surface of the slot antenna forming the inner wall of the processing chamber and the plasma. During propagation, part of the surface wave is absorbed by the plasma as an evanescent wave, and its electric field energy is used to generate and maintain the plasma. Hereinafter, the surface wave propagating along the boundary surface between the metal surface of the slot antenna and the plasma is also referred to as a metal surface wave (Metal Surface Wave). The slot may have an in-slot dielectric member and an O-ring for sealing the vacuum of the processing chamber from the atmosphere of the waveguide. As a result, the microwave is supplied to the processing chamber that is transmitted through the in-slot dielectric member and maintained in a desired vacuum state.

  According to this, only a rectangular waveguide (feeding waveguide and radiating waveguide) is used for the transmission line, and no coaxial waveguide is used. In rectangular waveguides, electromagnetic waves are transmitted through rectangular waveguides, so complicated design is not required as in coaxial waveguides, and the influence of design tolerances on transmission performance is not affected by coaxial waveguides. Smaller than that. As a result, the electromagnetic wave is transmitted to the plurality of radiation waveguides while being branched into multiple branches, and is emitted from each electrode when supplied to the processing chamber through a plurality of slot groups provided at an equal pitch on the ceiling surface. The electric field intensity of the electromagnetic wave becomes uniform, and uniform plasma can be generated. In addition, since all the transmission lines are formed of rectangular waveguides, high-power feeding can be realized as compared with coaxial waveguides. Further, the rectangular waveguide can be constructed simply as compared with the coaxial waveguide, so that labor can be saved not only in manufacturing and assembly but also in maintenance.

  The feeding waveguide and the plurality of radiation waveguides are adjacent to each other on the long side surface, and the feeding waveguide and the plurality of radiation waveguides are adjacent to each other on the adjacent surfaces. A plurality of power supply slots that communicate with the internal space of the tube may be formed.

  The slot group of the slot antenna may be formed on either the surface of the radiating waveguide where the feeding slot is formed or the surface facing the surface where the feeding slot is formed.

  The plurality of power supply slots may be formed to be inclined with respect to the longitudinal direction of the power supply waveguide and the longitudinal direction of each of the radiation waveguides.

  The adjacent feeding slots may be formed so as to be inclined by the same angle in the opposite direction with respect to the longitudinal direction of each radiation waveguide.

  The feeding waveguide may be vertically adjacent to the plurality of radiation waveguides in the vicinity of the end portions of the plurality of radiation waveguides.

  Two power supply waveguides are provided, and each of the two power supply waveguides is perpendicular to the plurality of radiation waveguides in the vicinity of both ends of the plurality of radiation waveguides. May be adjacent to

  The feeding waveguide may be vertically adjacent to the plurality of radiation waveguides at the center of the plurality of radiation waveguides.

In each slot group of the slot antenna, 2 ⁿ (n = 1, 2, 3) slots are formed, and all the slots formed in the plurality of slot groups are the length of the waveguide for radiation. It may be formed parallel or perpendicular to the direction, or may be inclined with respect to the longitudinal direction of the radiation waveguide.

  One end of the in-slot dielectric member may protrude from the metal surface of the slot antenna toward the processing chamber.

  The protruding portion of the in-slot dielectric member may be chamfered.

  In order to solve the above problems, according to another aspect of the present invention, there is provided a power supply method for a plasma processing apparatus for supplying an electromagnetic wave to a processing chamber in which plasma processing is performed, the step of outputting the electromagnetic wave from an electromagnetic wave source A step of transmitting the output electromagnetic wave to a power supply waveguide connected to the electromagnetic wave source; and a plurality of electromagnetic waves transmitted through the power supply waveguide to the power supply waveguide. Transmitting to the radiating waveguide; and electromagnetic waves transmitted through the plurality of radiating waveguides every integral multiple of an in-tube wavelength λg / 2 of the electromagnetic waves transmitted through the radiating waveguide in a metal slot antenna. And entering the processing chamber from a slot group including two or more slots formed at equal intervals along the metal surface of the slot antenna forming the inner wall of the processing chamber. Feeding method for a plasma processing apparatus including a step of transportable, it is provided.

  As described above, according to the present invention, the entire transmission line is configured simply by using a feeding waveguide and a radiating waveguide for the transmission line, and the electric field strength of the electromagnetic wave emitted from each electrode is reduced. By making it uniform, uniform plasma can be stably generated.

It is a longitudinal cross-sectional view (2-2 cross section of FIG. 2) of the plasma processing apparatus which concerns on the 1st-3rd embodiment of this invention. It is the figure which showed the ceiling surface (1-1 cross section of FIG. 1) of the plasma processing apparatus containing the transmission line which concerns on 1st Embodiment. It is the perspective view which expanded the connection part of the transmission line which concerns on 1st Embodiment. It is a figure for demonstrating transmission of the microwave in the transmission line which concerns on 1st Embodiment. FIGS. 5A and 5B are diagrams for explaining the propagation of microwaves and the distribution of energy in the transmission line according to the first embodiment. It is a figure for demonstrating the transmission state of the microwave in the transmission line which concerns on the modification 1 of 1st Embodiment. It is the figure which showed the ceiling surface of the plasma processing apparatus containing the transmission line which concerns on the modification 2 of 1st Embodiment. It is the figure which showed the ceiling surface of the plasma processing apparatus containing the transmission line which concerns on the modification 3 of 1st Embodiment. It is the perspective view which expanded the connection part of the transmission line which concerns on 2nd Embodiment. It is the perspective view which expanded the connection part of the transmission line which concerns on 3rd Embodiment. It is the figure which showed the prior art example of the transmission line using a coaxial waveguide.

  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In the present specification and drawings, elements having substantially the same configuration are denoted by the same reference numerals, and redundant description is omitted.

<First Embodiment>
First, a microwave plasma processing apparatus according to a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a longitudinal sectional view (cross section 2-2 in FIG. 2) of the microwave plasma processing apparatus according to the present embodiment. FIG. 2 is a view (cross section 1-1 in FIG. 1) showing a ceiling surface of the microwave plasma processing apparatus.

  The microwave plasma processing apparatus 100 according to the present embodiment is an example of a plasma processing apparatus that generates a plasma by exciting a gas with the energy of electromagnetic waves and performs a plasma process on an object to be processed in a processing chamber. The plasma process includes a process for finely processing the substrate G by the action of plasma, such as a film forming process or an etching process.

(Configuration of microwave plasma processing equipment)
The microwave plasma processing apparatus 100 includes a processing container 10 and a lid 20. The processing container 10 has a bottomed cubic shape whose upper part is opened. The processing chamber U is defined by the processing container 10 and the lid 20. An O-ring 21 is provided on the contact surface between the processing container 10 and the lid 20. Thereby, the airtightness of the processing chamber U is maintained. The processing container 10 and the lid 20 are made of a metal such as aluminum, for example, and are electrically grounded.

  A susceptor 11 (mounting table) is provided at the center of the processing container 10, and a substrate G is placed on the susceptor 11. The susceptor 11 is made of, for example, aluminum nitride, and a power feeding unit 11a and a heater 11b are provided therein.

  A high frequency power source 12b is connected to the power supply unit 11a via a matching unit 12a (for example, a capacitor). In addition, a high-voltage DC power supply 13b is connected to the power supply unit 11a via a coil 13a. The high frequency power supply 12b and the high voltage DC power supply 13b are grounded.

  The power feeding unit 11a applies a predetermined bias voltage to the inside of the processing container 10 by the high frequency power output from the high frequency power source 12b. In addition, the power feeding unit 11a electrostatically attracts the substrate G with a DC voltage output from the high-voltage DC power supply 13b. An AC power supply 14 provided outside the processing container 10 is connected to the heater 11b, and the substrate G is held at a predetermined temperature by an AC voltage output from the AC power supply 14.

  The bottom surface of the processing container 10 is opened in a cylindrical shape, and one end of a bellows 15 is attached to the outer peripheral edge thereof. The other end of the bellows 15 is fixed to the elevating plate 16. In this way, the opening at the bottom of the processing container 10 is sealed by the bellows 15 and the lifting plate 16.

  The susceptor 11 is supported by a cylinder 17 installed on the elevating plate 16 and moves up and down integrally with the elevating plate 16 and the cylinder 17, thereby raising the susceptor 11 to a height corresponding to the processing process. It comes to adjust. A baffle plate 18 for controlling the gas flow in the processing chamber U to a preferable state is provided around the susceptor 11.

  A vacuum pump (not shown) provided outside the processing container 10 is provided at the bottom of the processing container 10. The vacuum pump discharges the gas in the processing container 10 through the gas discharge pipe 19 to reduce the pressure in the processing chamber U to a desired degree of vacuum.

  As shown in FIG. 2, the lid 20 has a feeding waveguide 30 directly connected to the microwave source 40, six radiation waveguides 31 connected to the feeding waveguide 30, and slots. An antenna 32 (see FIG. 1) is embedded.

  The feeding waveguide 30 is connected perpendicularly to each of the radiation waveguides 31 in the vicinity of the ends of the plurality of radiation waveguides 31. The six radiation waveguides 31 are provided side by side at equal intervals. One feeding waveguide 30 and six radiating waveguides 31 are transmission lines for transmitting microwaves output from the microwave source 40, and are composed of only rectangular waveguides, and are coaxial waveguides. Is not used. The number of the power feeding waveguide 30 and the radiation waveguide 31 is not limited to this.

Returning to FIG. 1, the inside of the radiating waveguide 31 is filled with a dielectric member 33 such as fluororesin (for example, Teflon (registered trademark)), alumina (Al ₂ O ₃ ), quartz, or the like. The dielectric member 33 controls the in-tube wavelength λg ₁ of the microwave that is transmitted through each radiation waveguide 31 according to the equation λg ₁ = λc / (ε ₁ ) ^1/2 . Here, λc is the wavelength of free space, and ε ₁ is the dielectric constant of the dielectric member 33.

The slot antenna 32 is configured integrally with the lid 20 at the lower portion of the radiation waveguide 31. The slot antenna 32 is made of a metal that is a nonmagnetic material such as aluminum. In the slot antenna 32, a slot group 32 ag formed of the four radiation slots 32 a (openings) shown in FIG. 2 is formed on the lower surface of each radiation waveguide 31. Adjacent slot groups 32ag are arranged at equal intervals. The pitch may be a length that is an integral multiple of the in-tube wavelength λg _1/2 of the microwave that is transmitted through each radiation waveguide 31. In the present embodiment, the pitch of the slot group 32ag is λg _1/2 .

As shown in FIG. 1, the inside of each radiation slot 32a is filled with an in-slot dielectric member 36 made of a dielectric material such as fluororesin, alumina (Al ₂ O ₃ ), quartz, etc. The slot 32a is closed. During manufacturing, the in-slot dielectric member 36 and the slot antenna 32 are integrally fired at a predetermined temperature. According to this, the in-slot dielectric member 36 and the slot antenna 32 are brought into close contact with each other by integral firing. As a result, the radiation waveguide 31 and the like communicating with the atmosphere and the inside of the processing chamber in a vacuum state can be shut off.

  FIG. 3 is a perspective view of a connecting portion between the power feeding waveguide 30 and the radiation waveguide 31. The feeding waveguide 30 and the six radiating waveguides are adjacent to each other on their long side surfaces (H surfaces) and are vertically connected. On the adjacent surface, a feeding slot 30 a that communicates the internal space of the feeding waveguide 30 and the radiating waveguide 31 is formed for each radiating waveguide 31. Each of the feeding slots 30 a is formed to be inclined by 45 degrees with respect to the longitudinal direction of the feeding waveguide 30 and the longitudinal direction of each radiation waveguide 31. Adjacent feeding slots 30 a are inclined at the same angle in the opposite direction with respect to the longitudinal direction of each radiation waveguide 31. However, the inclination angle of the power supply slot 30a is not limited to 45 degrees, and any angle can be used as long as it generates circularly polarized waves that evenly distribute the microwave energy. The slot antenna 32 is also provided with a radiation slot 32 a on the long side surface of the radiation waveguide 31.

With this configuration, the microwaves are transmitted through the power feeding waveguides 30, passed through the power feeding slots 30 a, and transmitted through the six radiation waveguides 31 while being branched. Are incident from the radiation slots 32a of the plurality of slot groups 32ag provided in the substrate, and are transmitted through the plurality of in-slot dielectric members 36 and supplied to the processing chamber. At that time, the in-slot dielectric member 36 controls the in-tube wavelength λg ₂ of the microwave transmitted through each radiation slot 32a in accordance with the equation of λg ₂ = λc / (ε ₂ ) ^1/2 . Here, ε ₂ is the dielectric constant of the in-slot dielectric member 36.

  In the microwave plasma processing apparatus 100 according to the present embodiment, the dielectric for propagating the surface wave of the microwave is not provided on the lower surface of the slot antenna 32. Therefore, the metal surface of the slot antenna 32 is exposed on the ceiling surface of the present apparatus shown in FIG. Accordingly, the microwave supplied into the processing chamber propagates along the metal surface of the slot antenna 32 that forms a metal surface wave and forms the inner wall of the processing chamber. The end portion of the in-slot dielectric member 36 protrudes from the radiation slot 32a to the processing chamber side by about 1 mm to 5 mm. As a result, microwaves are easily emitted from the in-slot dielectric member 36.

  The gas supply source 42 shown in FIG. 1 is connected to the gas line Lin. As shown in the ceiling surface of FIG. 2, the gas line Lin is connected to a plurality of gas introduction pipes 43 provided at equal intervals. The gas supplied from the gas supply source 42 is introduced into the processing chamber while being diverted to the respective gas introduction pipes 43 via the gas line Lin.

  The cooling water pipe 44 is embedded in the lid 20 and is connected to the refrigerant supply source 45. The cooling water supplied from the refrigerant supply source 45 circulates in the cooling water pipe 44 and returns to the refrigerant supply source 45, so that the lid 20 is maintained at a desired temperature.

  With the configuration described above, the gas supplied from the gas supply source 42 is excited by the electric field energy of the incident microwave, thereby generating a plasma above the substrate G and performing a plasma treatment on the substrate G. Is done.

(Microwave transmission / propagation)
Next, microwave transmission on the transmission line will be described with reference to FIGS. 4 and 5. 4 shows microwave transmission in the power feeding waveguide 30 and the radiation waveguide 31, and FIGS. 5A and 5B show microwave propagation in the vicinity of the slot antenna.

  As described above, the feeding waveguide 30 is in close contact with and connected to each of the radiating waveguides 31 in the vicinity of the end portions of the six radiating waveguides 31. ) Are coupled to each other by feeding slots 30a inclined at an angle of 45 degrees. Thus, by forming the slot 32a on the long side surface of the radiation waveguide 31, the slot 32a that can be formed in one radiation waveguide 31 can be formed rather than forming the slot on the short side surface. You can increase the number. Thereby, the number of the radiation waveguides 31 required can be reduced.

  In general, an electric field E is generated perpendicularly to the longitudinal direction of the rectangular waveguide on the short side surface of the rectangular waveguide, and a current flows along the electric field E. On the other hand, on the surface on the long side of the rectangular waveguide, an annular magnetic field pattern is generated for each in-tube wavelength λg / 2, and an electric field E is generated from outside to inside or from inside to outside of the annular magnetic field pattern. A current flows along.

  In FIG. 4, one state of an electric field and a magnetic field generated in the power supply waveguide 30 when microwaves are transmitted through the power supply waveguide 30 is indicated by a broken line and a solid line. The electric field generated when the microwave current is passed through the feeding slot 30a is perpendicular to the longitudinal direction of the feeding slot 30a. On the other hand, the magnetic field generated at this time is all parallel to the conductor surface of the power supply waveguide 30, and the magnetic field and the electric field interact with each other while being always orthogonal. Therefore, the magnetic field generated when the microwave current is passed through the power supply slot 30a is parallel to the longitudinal direction of the power supply slot 30a, and the magnetic field lines of the component parallel to the power supply slot 30a pass through the power supply slot 30a. Can do. In FIG. 4, the magnetic field lines passing through the power supply slot 30a are indicated by solid lines.

  Since the feeding slot 30a is inclined, the microwave passes through the feeding slot 30a while being circularly polarized. For this reason, the magnetic field lines that have just passed through the power supply slot 30a are elliptical in an oblique direction. However, when the microwave is transmitted through the radiating waveguide 31 in the right direction on the drawing sheet, the magnetic lines of force become circular or elliptical with no inclination. This is because only the fundamental mode magnetic field lines are transmitted to the radiation waveguide 31.

  The upper view of FIG. 5 shows a 3-3 cross section of FIG. As shown in FIG. 5, in the radiating waveguide 31, the slot group 32ag is cut at a pitch of λg / 2. Therefore, at the position of each radiating slot 32a in the plurality of slot groups 32ag, the radiating guide is provided. The absolute value of the amplitude of the standing wave of the microwave formed in the internal space of the wave tube 31 is equal. Accordingly, the absolute values of the amplitudes of the microwaves supplied from the radiation slots 32a to the processing chamber among the microwaves transmitted through the radiation waveguide 31 become equal. Therefore, the electric field strength of the microwaves supplied from each of the radiating slots 32a is substantially the same, and propagates on the boundary surface between the metal surface of the slot antenna 32 and the plasma as a metal surface wave MSW (Metal Surface Wave). During propagation, a uniform plasma is generated in the vicinity of the ceiling surface due to the electric field energy of the metal surface wave MSW evenly distributed.

(Relationship between metal surface wave propagation and frequency)
The dielectric constant (ε _r ′ −jε _r ″) of the plasma is expressed by the following equation (1).

The propagation characteristics when microwaves are incident on the plasma are expressed by the following equation (2).
Here, k is the wave number, k ₀ is the wave number in vacuum, ω is the frequency of the metal surface wave, ν _c is the electron collision frequency, and ω _pe is the electron plasma frequency represented by the following equation (3).

Here, e is the elementary charge, n _e the electron density of the plasma, epsilon ₀ is the dielectric constant, m _e in a vacuum is the electron mass.

The distance that the microwave has entered before the electric field intensity E of the microwave has attenuated to 1 / e of the electric field intensity E ₀ at the boundary surface of the plasma is the penetration length δ. The approach length δ is expressed by the following equation (4).
δ = −1 / Im (k) (4)
k is the wave number.

When the electron density n _e is higher than the cut-off density n _c represented by the following formula (5), the microwave is reflected in the vicinity of the plasma surface, it propagates the inner surface of the processing chamber as the surface waves.
n _c = ε ₀ m _e ω ² / e ² (5)

  According to Equation (5), when microwaves having a low frequency of about 1 to 2 GHz are supplied, the microwaves supplied to the processing chamber propagate along the metal surface of the slot antenna 32 exposed to the ceiling surface and the plasma boundary surface. It becomes easy to do.

  In the microwave plasma processing apparatus 100 according to the present embodiment, as shown in FIGS. 1 and 2, a substantially rectangular groove 50 is formed on the metal surface in the vicinity of the outer periphery of the slot antenna 32 that forms the ceiling surface. The propagation of the metal surface wave MSW is inhibited by the groove 50 so that the metal surface wave MSW does not propagate more than necessary.

(Projection of dielectric member in slot)
As shown in the lower view of FIG. 5 in which the portion Ex in the upper view of FIG. 5 is enlarged, in the present embodiment, one end of the in-slot dielectric member 36 is exposed to the lower surface of the slot antenna 32 (that is, to the processing chamber side). Projecting from the metal surface of the slot antenna 32) to the processing chamber side. As a result, microwaves are easily emitted from the in-slot dielectric member 36. The protruding portion of the in-slot dielectric member 36 is chamfered. The width in the short direction of the outer chamfered portion OC is 5 mm with respect to the width in the short direction of the inner chamfered portion IC of 0.2 mm. According to the simulation performed by the inventor, this allows the energy of the microwave output from the outer chamfered portion OC to be distributed to about twice the energy of the microwave output from the inner chamfered portion IC. it can. As a result, uniform plasma can be generated.

  As described above, according to the microwave plasma processing apparatus 100 according to the present embodiment, the transmission line is configured by only rectangular waveguides (the feeding waveguide 30 and the radiating waveguide 31), and is coaxial. Do not use waveguide lines for transmission lines. According to this, the microwave is transmitted only in the internal space of the rectangular waveguide. As a result, the required circuit design is limited to the internal space of the rectangular waveguide, and no complicated design is required unlike the coaxial waveguide, and the effect of design tolerances on transmission performance is reduced compared to the coaxial waveguide. can do. As a result, the electric field strength of the microwave supplied to the processing chamber through the plurality of slot groups can be made uniform, and uniform plasma can be generated. In addition, since the transmission line and the periphery of the electrode can be simply configured, there is an advantage in the manufacture, assembly, and maintenance of the transmission line. In addition, higher power feeding than a coaxial waveguide can be realized.

(Modification 1 of the first embodiment)
Next, the transmission line of the microwave plasma processing apparatus 100 according to the first modification of the first embodiment will be described with reference to FIG. In the first modification, the four radiation slots 32a forming the slot group 32ag are formed in a rhombus shape so as to face each other at a position inclined by 45 degrees with respect to the longitudinal direction of the radiation waveguide 31. ing. By arranging the radiation slots 32a to be inclined in this manner, the microwaves supplied from the radiation slots 32a to the processing chambers are supplied to the processing chambers while being circularly polarized. In the case of circular polarization, the generated electromagnetic field leaks from the four radiation slots 32a while rotating and is transmitted more uniformly into the processing vessel 10.

  Further, since the radiating slots 32 a 1 to 32 a 4 are disposed at an angle of 45 degrees with respect to the longitudinal direction of the radiating waveguide 31, the metal surface wave MSW propagating on the ceiling surface is generated in the longitudinal direction of the radiating waveguide 31. It propagates radially toward the direction of 45 degrees diagonally. As a result, since the metal surface wave MSW easily propagates in the angular direction of the ceiling surface of the processing chamber together with the chamfering effect of the in-slot dielectric member 36, more uniform plasma can be generated.

(Modification 2 of the first embodiment)
Next, the transmission line of the microwave plasma processing apparatus 100 according to the second modification of the first embodiment will be described. FIG. 7 shows a transmission line according to the second modification. In the second modification, two feeding waveguides 30 are vertically connected in the vicinity of both end portions of the six radiating waveguides 31. A microwave source 40 is connected to each power supply waveguide 30. The cost may be reduced by connecting one microwave source 40 to each of the power supply waveguides 30. The feeding slots 30a provided on both sides of the radiation waveguide 31 are inclined at the same angle in the opposite direction. Thereby, the microwave is transmitted to each radiation waveguide 31 with the same amplitude from both ends of each radiation waveguide 31. According to this, even when the longitudinal direction of the radiating waveguide 31 becomes longer as the apparatus becomes larger, microwaves can be more evenly supplied from the slot groups 32ag into the processing chamber. As a result, more uniform plasma can be generated over a wide area on the large substrate.

(Modification 3 of the first embodiment)
Next, a transmission line of the microwave plasma processing apparatus 100 according to Modification 3 of the first embodiment will be described. FIG. 8 shows a transmission line according to the third modification. In the third modification, one feeding waveguide 30 is vertically connected to the central portion of the six radiating waveguides 31. A microwave source 40 is connected to the power supply waveguide 30. Thus, the microwaves are transmitted with the same amplitude from the central side of each radiation waveguide 31 toward both ends of each radiation waveguide 31. Thereby, even when the longitudinal direction of the radiating waveguide 31 becomes longer with the increase in the size of the apparatus, the microwaves can be supplied more uniformly from the respective slot groups 32ag into the processing chamber. Plasma can be generated.

<Second Embodiment>
Next, the transmission line of the microwave plasma processing apparatus 100 according to the second embodiment will be briefly described. FIG. 9 shows a transmission line according to the second embodiment. In the second embodiment, the three microwave sources 40 are respectively connected to the two radiation waveguides 31 via Y branch tubes 41 (Y-branched feeding waveguides). The four radiation slots 32 a are formed in a diamond shape at a position inclined by 45 degrees with respect to the longitudinal direction of the radiation waveguide 31. Of course, each radiation slot 32a of each slot group 32ag may be parallel or perpendicular to the longitudinal direction of the radiation waveguide as shown in the first embodiment.

  Thereby, the microwave is transmitted to the six radiating waveguides 31 in the lid 20 while being Y-branched by the Y-branch tube 41. The microwave transmitted through the radiation waveguide 31 is incident from the radiation slot 32a and supplied into the processing chamber. Also by this, uniform plasma can be generated by the electric field energy of the microwave supplied uniformly. However, in the case of this embodiment, the transmission line tends to be larger than that in the first embodiment.

<Third Embodiment>
Next, the transmission line of the microwave plasma processing apparatus 100 according to the third embodiment will be described. FIG. 10 shows a transmission line according to the third embodiment. In the third embodiment, one microwave source 40 is π-branched by a feeding waveguide 52 and connected to six radiation waveguides 31, respectively. The slot group 32ag formed in the radiation waveguide 31 is the same as that in the second embodiment. Of course, it may be parallel or perpendicular to the longitudinal direction of each radiation slot 32a of each slot group 32ag and the radiation waveguide.

  Thus, the microwaves are transmitted to the six radiating waveguides 31 while being π-branched in the feeding waveguide 52. The microwave transmitted through the radiation waveguide 31 is incident from the radiation slot 32a and supplied into the processing chamber. Also by this, uniform plasma can be generated by the electric field energy of the microwave supplied uniformly. However, in the case of this embodiment, the transmission line tends to be larger than that in the first embodiment.

  As described above, according to the microwave plasma processing apparatus 100 according to each embodiment, only a rectangular waveguide is used for the transmission line. Thereby, the microwave of the same energy can be emitted into the processing chamber from the radiation slots arranged evenly on the ceiling surface without complicating impedance adjustment. As a result, uniform plasma can be generated.

  In the above description, the slot group is formed on the long side surface (H surface) of the waveguide. However, a rectangular slot may be formed on the short side surface (E surface) of the waveguide. Good. The slot interval is an integral multiple of the guide wavelength λg / 2.

  In the above embodiment, the operations of the respective units are related to each other, and can be replaced as a series of operations and a series of processes in consideration of the mutual relations. Thereby, embodiment of a plasma processing apparatus can be made into embodiment of the electric power feeding method of a plasma processing apparatus.

  Accordingly, there is provided a power supply method for a plasma processing apparatus for supplying an electromagnetic wave to a processing chamber in which a plasma treatment is performed, the step of outputting the electromagnetic wave from an electromagnetic wave source, and the output electromagnetic wave is coupled to the electromagnetic wave source Transmitting to the power supply waveguide, transmitting the electromagnetic wave transmitted through the power supply waveguide to a plurality of radiation waveguides connected to the power supply waveguide, and the plurality of radiations A group of slots including two or more slots formed at equal intervals for every integral multiple of the in-tube wavelength λg / 2 of the electromagnetic wave transmitted through the radiating waveguide in the metal slot antenna. And a step of propagating the incident electromagnetic wave along the metal surface of the slot antenna that forms the inner wall of the processing chamber. It is possible to provide a power supply method.

  As mentioned above, although preferred embodiment of this invention was described in detail, referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to this example. It is obvious that a person having ordinary knowledge in the technical field to which the present invention pertains can come up with various changes or modifications within the scope of the technical idea described in the claims. Of course, it is understood that these also belong to the technical scope of the present invention.

  For example, the slot group of the slot antenna may be formed on the same side as the long side surface where the feeding slot of the radiating waveguide is formed, and the long side side where the feeding slot is formed. You may form in the surface (surface of a long side) facing a surface.

  In addition, for example, a Y-branch or π-branch feeding waveguide may be coupled to one end of each radiation waveguide, or may be coupled to both ends of a plurality of radiation waveguides.

  Further, in the in-slot dielectric member and the slot antenna according to the present invention, a sealing material such as an O-ring is provided on the contact surface between the in-slot dielectric member and the slot antenna instead of integrally firing the in-slot dielectric member and the slot antenna. Thus, the airtightness in the processing chamber may be maintained.

  The microwave output from the microwave source according to the present invention may be 896 MHz, 915 MHz, 922 MHz, 2.45 GHz, or the like. The microwave source is an example of an electromagnetic wave source that outputs an electromagnetic wave for exciting plasma, and includes a magnetron and a high frequency power source as long as the electromagnetic wave source outputs an electromagnetic wave of 100 MHz or higher.

Note that the size of the substrate G (glass substrate) may be 720 mm × 720 mm or more. For example, the G3 substrate size is 720 mm × 720 mm (dimension in the chamber: 400 mm × 500 mm), and the G4.5 substrate size is 730 mm × 920 mm. (Dimension in chamber: 1000 mm × 1190 mm), 1100 mm × 1300 mm in G5 substrate size (dimension in chamber: 1470 mm × 1590 mm). A microwave having a power of 1 to 8 W / cm ² is supplied into the processing chamber having the above size.

  Further, in the present invention, it is preferable to provide the in-slot dielectric member inside the slot because the electric field strength of the microwave can be controlled. However, the in-slot dielectric member need not necessarily be provided inside the slot.

  The plasma processing apparatus according to the present invention is not limited to the microwave plasma processing apparatus described in the above embodiment, and can be used for all plasma processing apparatuses that supply power using rectangular waveguides and slots.

DESCRIPTION OF SYMBOLS 100 Microwave plasma processing apparatus 10 Processing container 20 Cover body 30,52 Feeding waveguide 30a Feeding slot 31 Radiation waveguide 32 Slot antenna 32a Radiation slot 32ag Slot group 36 In-slot dielectric member 40 Microwave source 41 Y Branch pipe 43 Gas introduction pipe 50 Groove MSW Metal surface wave

Claims (13)

A plasma processing apparatus that excites a gas by energy of electromagnetic waves to generate plasma, and performs plasma processing on an object to be processed in a processing chamber,
An electromagnetic wave source that outputs electromagnetic waves;
A feeding waveguide coupled to the electromagnetic wave source;
A plurality of radiation waveguides connected to the power supply waveguide and having an internal space communicating with the internal space of the power supply waveguide;
A slot group including two or more radiating slots provided adjacent to the plurality of radiating waveguides is set at every integral multiple of an in-tube wavelength λg / 2 of an electromagnetic wave transmitted through the plurality of radiating waveguides. A plurality of metal slot antennas formed at intervals, and
The slot antenna for supplying an electromagnetic wave transmitted from the feeding waveguide to the plurality of radiating waveguides through the slot groups formed at equal intervals into the processing chamber to form an inner wall of the processing chamber Plasma processing apparatus that propagates along the metal surface of   The feeding waveguide and the plurality of radiating waveguides are adjacent to each other on the long side surface, and the feeding waveguide and the plurality of waveguides on the adjacent long side surface. The plasma processing apparatus according to claim 1, wherein a plurality of power supply slots communicating with the internal space with the radiation waveguide are formed.   3. The slot group of the slot antenna is formed on either a surface of the radiating waveguide where the feeding slot is formed or a surface facing the surface where the feeding slot is formed. Plasma processing equipment.   The plasma processing apparatus according to claim 3, wherein the plurality of power supply slots are formed to be inclined with respect to a longitudinal direction of the power supply waveguide and a longitudinal direction of each of the radiation waveguides.   The plasma processing apparatus according to claim 4, wherein the adjacent power supply slots are formed so as to be inclined by the same angle in the opposite direction with respect to the longitudinal direction of each radiation waveguide.   The plasma processing according to any one of claims 1 to 5, wherein the power supply waveguide is adjacent to the plurality of radiation waveguides in the vicinity of ends of the plurality of radiation waveguides. apparatus. Two power supply waveguides,
6. Each of the two power supply waveguides is adjacent to the plurality of radiation waveguides in the vicinity of both end portions of the plurality of radiation waveguides. 7. The plasma processing apparatus according to 1.   The plasma processing apparatus according to claim 1, wherein the power supply waveguide is vertically adjacent to the plurality of radiation waveguides at a center of the plurality of radiation waveguides. In each slot group of the slot antenna, 2 ⁿ (n = 1, 2, 3) slots are formed,
All the slots formed in the plurality of slot groups are formed parallel or perpendicular to the longitudinal direction of the radiation waveguide, or inclined with respect to the longitudinal direction of the radiation waveguide. The plasma processing apparatus as described in any one of Claims 1-8 formed.   The plasma processing apparatus according to any one of claims 1 to 9, further comprising two or more in-slot dielectric members that respectively close the insides of the slots of the slot group.   The plasma processing apparatus according to claim 10, wherein one end of the in-slot dielectric member protrudes toward the processing chamber from a metal surface of the slot antenna.   The plasma processing apparatus according to claim 11, wherein the protruding portion of the in-slot dielectric member is chamfered. A power supply method for a plasma processing apparatus for supplying electromagnetic waves to a processing chamber in which plasma processing is performed,
Outputting electromagnetic waves from an electromagnetic wave source;
Transmitting the output electromagnetic wave to a power supply waveguide connected to the electromagnetic wave source;
Transmitting the electromagnetic wave transmitted through the power supply waveguide to a plurality of radiation waveguides connected to the power supply waveguide; and
Two or more slots formed at equal intervals at every integral multiple of the in-tube wavelength λg / 2 of the electromagnetic wave transmitted through the radiation waveguide in a metal slot antenna. Entering the processing chamber from a slot group including:
Propagating the incident electromagnetic wave along the metal surface of the slot antenna that forms the inner wall of the processing chamber.