JP4197541B2 - Microwave antenna and microwave plasma processing apparatus - Google Patents

Description

  The present invention relates to an annular tubular portion for propagating microwaves, an introduction port opened on a side surface of the tubular portion for introducing microwaves into the tubular portion, and a micro tube to the annular tubular portion connected to the introduction port. Etching or ashing or the like on a semiconductor substrate or a glass substrate for a liquid crystal display by a microwave antenna having a tubular portion for supplying a wave, and plasma generated using the microwave radiated from the microwave antenna The present invention relates to a microwave plasma processing apparatus that performs the process.

  Plasma generated by applying energy to the reaction gas from the outside is widely used in manufacturing processes such as LSI or LCD. In particular, the use of plasma has become an indispensable basic technology in the dry etching process. Generally, there are a case where a microwave of 2.45 GHz is used as an excitation means for generating plasma and a case where RF (Radio Frequency) of 13.56 MHz is used. The former has advantages in that a higher-density plasma can be obtained than the latter, and no electrode is required for plasma generation, thus preventing contamination from the electrode.

However, in the plasma processing apparatus using microwaves, it is difficult to generate plasma so that the area of the plasma generation region is widened and the density is uniform. However, since the microwave plasma processing apparatus has various advantages as described above, it has been required to realize processing of a large-diameter semiconductor substrate, an LCD glass substrate, and the like by this apparatus.
In order to satisfy this requirement, the present applicant has proposed a microwave plasma processing apparatus using an annular waveguide antenna as shown in the side sectional view of FIG. 16 and the plan view of FIG. Yes.

  In this microwave plasma processing apparatus, a bottomed cylindrical reactor 1 is entirely formed of aluminum. A microwave introduction window is opened at the top of the reactor 1, and this microwave introduction window is sealed in an airtight state by a sealing plate 4. The sealing plate 4 is made of a dielectric material such as quartz glass or alumina that has heat resistance and microwave transparency and has a small dielectric loss.

  A cover member 17 formed by molding a conductive metal into a circular lid shape is fitted on the sealing plate 4, and the cover member 17 is fixed on the reactor 1. An antenna 10 for introducing microwaves into the reactor 1 is provided on the upper surface of the cover member 17. The antenna 10 is fixed to the upper surface of the cover member 17, and includes an annular waveguide type antenna portion 11 formed by annularly forming a member having a U-shaped cross-sectional view. A plurality of openings 15, 15,... Are opened in a portion facing the tube antenna unit 11.

  The annular waveguide antenna unit 11 is provided slightly inside the inner peripheral surface of the reactor 1 and concentrically with the central axis of the reactor 1, and an annular guide is provided around the introduction port provided on the outer peripheral surface. An introduction portion 16 for introducing a microwave into the wave tube antenna portion 11 is connected so as to be in the diameter direction of the annular waveguide antenna portion 11. A dielectric 14 such as a fluorine resin such as Teflon (registered trademark), a polyethylene resin, or a polystyrene resin (preferably Teflon) is fitted in the introduction portion 16 and the annular waveguide antenna portion 11.

  A waveguide 21 extending from the microwave oscillator 20 is connected to the introduction section 16, and the microwave oscillated by the microwave oscillator 20 is incident on the introduction section 16 of the antenna 10 through the waveguide 21. . This incident wave is introduced from the introduction portion 16 to the annular waveguide antenna portion 11. The microwave introduced into the annular waveguide antenna unit 11 travels through the dielectric 14 in the annular waveguide antenna unit 11 as traveling waves traveling in the opposite directions in the annular waveguide antenna unit 11. Both propagating waves propagate and collide at a position facing the inlet of the annular waveguide antenna unit 11 to generate a standing wave. By this standing wave, a current having a maximum value flows at a predetermined interval on the inner surface of the annular waveguide antenna unit 11.

  At this time, according to the microwave frequency of 2.45 GHz, the annular waveguide antenna unit is set so that the microwave mode propagating in the annular waveguide antenna unit 11 is the rectangular TE10 which is the basic propagation mode. 11 dimensions are 27 mm high and 66.2 mm wide. The microwave in this mode propagates through the dielectric 14 in the annular waveguide antenna unit 11 with almost no energy loss.

  Further, when the sealing plate 4 having a diameter of 380 mm is used and Teflon (registered trademark) having εr (relative dielectric constant) = 2.1 is fitted into the annular waveguide antenna portion 11, the annular waveguide antenna The dimension from the center of the section 11 to the center in the width direction of the annular waveguide antenna section 11 is 141 mm. In this case, the circumferential length (approximately 886 mm) of the circle connecting the center in the width direction of the annular waveguide antenna unit 11 is the wavelength of the microwave propagating in the annular waveguide antenna unit 11 (approximately 110 mm). ). Therefore, the microwave resonates in the annular waveguide antenna unit 11, and the above-mentioned standing wave becomes a high voltage / low current at the antinode position and a low voltage / high current at the node position. A Q value of 10 is improved.

The openings 15, 15,... Are formed in the portion of the cover member 17 facing the annular waveguide antenna unit 11 in the diameter direction of the annular waveguide antenna unit 11, that is, inside the annular waveguide antenna unit 11. It is opened in a strip shape so as to be orthogonal to the traveling direction of the propagating microwave. When the annular waveguide antenna unit 11 has the dimensions described above, the length of each opening 15, 15,... Is 50 mm, and the width is 20 mm.
Each of the openings 15, 15,... Is substantially radially provided in the cover member 17, so that the microwaves are uniformly introduced into the entire region in the reactor 1.

  A through hole penetrating the cover member 17 and the sealing plate 4 is formed at the approximate center of the cover member 17, and a required gas is introduced into the processing chamber 2 from the gas introduction pipe 5 fitted into the through hole. be introduced. In the center of the bottom wall of the processing chamber 2, a mounting table 3 on which the sample W is mounted is provided, and a high-frequency power source 7 is connected to the mounting table 3 via a matching box 6. An exhaust port 8 is provided in the bottom wall of the reactor 1, and the inside air of the processing chamber 2 is discharged from the exhaust port 8.

In order to perform an etching process on the surface of the sample W using such a microwave plasma processing apparatus, the processing chamber 2 is evacuated from the exhaust port 8 to a desired pressure, and then the processing chamber 2 is connected to the processing chamber 2. The reaction gas is supplied into 2. Next, a microwave is oscillated from the microwave oscillator 20 and introduced into the antenna 10 through the waveguide 21 to form a standing wave there. This standing wave passes through the openings 15, 15,... Of the antenna 10 and the sealing plate 4 and is introduced into the processing chamber 2, and plasma is generated in the processing chamber 2. Etch.
JP 2000-106359 A Japanese Patent Laid-Open No. 9-289099 JP-A-11-111493 JP-A-6-216073 JP-A-6-204176 JP-A-7-130494 JP 7-153599 A

When the microwave is introduced from the microwave oscillator 20 through the waveguide 21 to the annular waveguide antenna unit 11, the microwave is transmitted at the connection portion between the waveguide 21 and the annular waveguide antenna unit 11. Some are reflected.
The microwave reflection will be described below.
When the antenna (load) side is viewed from the microwave introduction (transmission) side, the impedance Z _{L of the} entire antenna (load) side is connected to the characteristic impedance Z _O on the microwave introduction (transmission) side. The reflection coefficient S _{O at the} connection portion is expressed by the following equation.
S _O = (Z _L −Z _O ) / (Z _L + Z _O )

At this time, if Z _L = Z _O , the reflection coefficient is 0, and this state is called non-reflection, which indicates that matching is achieved.
However, reflection usually occurs because Z _L ≠ Z _O. As the reflection coefficient S _O increases, the microwave power is not efficiently supplied to the antenna (load) side, and returns to the power source side, resulting in a loss.
In the conventional technique using an annular waveguide antenna, a microwave matching unit is usually provided in the portion of the waveguide 21 between the microwave power source and the antenna (load), and reflected by the connecting portion. The electric power is sent back to the antenna (load) side again by the microwave matching unit.

Since the annular waveguide antenna section 11 and the introduction section 16 are greatly different in shape, impedance mismatch at the connecting section between them is extremely large, and the reflection coefficient is extremely high. When the reflection coefficient increases in this way, the microwave is repeatedly reflected (multiple reflection) between the microwave matching unit and the antenna (load), and is propagated to the annular waveguide antenna unit 11. Will be very low.
Therefore, in order to obtain the plasma with the same density, a microwave oscillator with a higher output is required, and the cost of the parts of the apparatus increases. Furthermore, since the electric field strength is increased between the connection portion and the microwave matching device, there arises a disadvantage that it is necessary to increase the power resistance value of the microwave matching device.

Further, when the dielectric 14 is inserted into the annular waveguide antenna unit 11, the electric field strength is increased by the dielectric 14, so that the problem due to the multiple reflection is further increased. Furthermore, it is necessary to design in consideration of the withstand voltage of the dielectric 14 with respect to an increase in electric field strength due to multiple reflection, which increases the cost of parts of the device.
On the other hand, a change in impedance of the annular waveguide antenna unit 11 affects an impedance mismatch at the connection part. In particular, a change in impedance near the opening 15 may be close to plasma and greatly affects the mismatch. This change in impedance is likely to occur when the annular waveguide antenna is removed for assembly or the like and the assembly is restored. Furthermore, the impedance change is likely to occur when the annular waveguide antenna unit 11 expands / contracts due to a temperature change of the device.

This invention is made | formed in view of the above situations, and it aims at providing the microwave antenna which can suppress reflection of the microwave in a connection part in 1st- 3rd invention. .
In the fourth and fifth inventions, an object is to provide a microwave plasma processing apparatus capable of efficiently generating plasma with less incident microwave power.

A microwave antenna according to a first aspect of the present invention is an annular first tubular portion for propagating microwaves, and one or a plurality of openings formed on a side surface of the first tubular portion so as to introduce microwaves into the first tubular portion. An introduction port, a second tubular portion connected to the introduction port for supplying microwaves into the first tubular portion, and opened in the first tubular portion for taking out the microwave from the first tubular portion In the microwave antenna having a plurality of openings, the first tubular portion includes a first side surface in which the opening is formed and two second side surfaces orthogonal to the first side surface and opposed to each other. A third side surface that is molded and perpendicular to the second side surface is detachably attached to the second side surface.

  In this microwave antenna, the first tubular portion is opened on the side surface of the first tubular portion so that the first tubular portion propagates the microwave and one or a plurality of inlets are introduced into the first tubular portion. The second tubular portion is connected to the introduction port and supplies the microwave into the first tubular portion, and a plurality of openings are opened in the first tubular portion, and the microwave is taken out from the first tubular portion. The first tubular portion is formed by integrally forming a first side surface having an opening and two second side surfaces orthogonal to the first side surface and facing each other, and a third side surface orthogonal to the second side surface is a second side surface. Is detachably attached.

  As a result, even when a dielectric is inserted into the first tubular portion, the dielectric can be replaced by attaching and detaching the third side surface, and the mechanical accuracy between the dielectric and the first tubular portion can be increased. Can be improved. In addition, the instability of impedance matching of the connecting portion due to the shift of the impedance of the first tubular portion due to the assembly error between the first side surface and the second side surface where the opening is opened can be removed, and the impedance of the connecting portion can be removed. Good alignment can be obtained.

Microwave antenna according to the second invention, the third aspect, the the wall forming the second side is attached by a plurality of screws, the mounting position of the screw, the first tubular from the center of the thickness of the wall It is close to the inside of the part.

In this microwave antenna, the third side surface is attached to the wall forming the second side surface by a plurality of screws, and the mounting position of the screw is close to the inside of the first tubular portion from the center of the thickness of the wall forming the second side surface. It is.
As a result, the third side surface and the wall forming the second side surface can be firmly connected. Therefore, even if the third side surface is detached or the temperature of the annular waveguide antenna changes, the impedance deviation does not occur. It is suppressed, the instability of impedance matching at the connecting portion can be removed, and impedance matching at the connecting portion can be satisfactorily taken.

Microwave antenna according to the third invention, the a second side wall forming the third side face, to the outside direction of the first tubular portion, characterized in that it has a space for no contact .

In this microwave antenna, the wall forming the second side surface and the third side surface have a space for preventing contact with the outside of the first tubular portion.
As a result, the third side surface and the wall forming the second side surface can be firmly connected. Therefore, even if the third side surface is detached or the temperature of the annular waveguide antenna changes, the impedance deviation does not occur. It is suppressed, the instability of impedance matching at the connecting portion can be removed, and impedance matching at the connecting portion can be satisfactorily taken.

A microwave plasma processing apparatus according to a fourth aspect of the present invention introduces microwaves through a sealing member into a container that is partially sealed with a sealing member, and generates plasma by the microwaves. in the microwave plasma processing apparatus for processing an object to be processed by the generated plasma, comprising a microwave antenna according to any one of claims 1-3, said opening said sealing member of said microwave antenna It is characterized by facing.

In this microwave plasma processing apparatus, a microwave is introduced through a sealing member through a sealing member partially sealed with a sealing member, plasma is generated by the microwave, and the plasma is generated by the generated plasma. Process the processed material. It has been opened in a microwave antenna according to any one of claims 1 to 3 faces the sealing member.
Thereby, it is possible to realize a microwave plasma processing apparatus that can efficiently generate plasma with less incident microwave power.

In the microwave plasma processing apparatus according to a fifth aspect of the present invention, the part of the first side surface where the opening of the microwave antenna is formed should cover the sealing member so that the microwave does not leak to the outside. It is characterized by being.

  In this microwave plasma processing apparatus, the portion forming the first side surface where the opening of the microwave antenna is formed is configured to cover the sealing member so that the microwave does not leak to the outside. The instability of impedance matching of the connecting portion due to the impedance deviation of the first tubular portion due to the assembly error between the first side surface of the first tubular portion and the cover member for covering the sealing member can be removed, In addition, leakage of microwaves to the outside can be prevented.

According to the microwave antenna according to the first invention, even when inserting the dielectric within the first tubular portion, by attaching and detaching the third aspect enables replacement of the dielectric, and further dielectric The mechanical accuracy with the first tubular portion can be improved. In addition, it is possible to remove instability of impedance matching of the connecting portion due to the impedance deviation of the waveguide in the first tubular portion due to the assembly error between the first side surface and the second side surface where the opening is opened, Can be satisfactorily matched.

According to the microwave antennas of the second and third inventions, the third side surface and the wall forming the second side surface can be firmly connected. Therefore, even if the third side surface is attached or detached, the annular waveguide antenna Even if the temperature changes, the impedance shift is suppressed, the instability of the impedance matching of the connecting portion can be removed, and the impedance matching of the connecting portion can be satisfactorily taken.

According to the microwave plasma processing apparatus of the fourth aspect of the invention, it is possible to realize a microwave plasma processing apparatus that can efficiently generate plasma with less incident microwave power.

According to the microwave plasma processing apparatus of the fifth aspect of the present invention, the impedance deviation of the first tubular portion due to the assembly error between the first side surface of the first tubular portion of the microwave antenna and the cover member for covering the sealing member is caused. The instability of impedance matching caused by the connection portion can be removed, and leakage of the microwave to the outside can be prevented.

Embodiments of the present invention will be described below with reference to the drawings showing the embodiments.
Embodiment 1 FIG.
FIG. 1 is a side sectional view showing the structure of a microwave antenna and a microwave plasma processing apparatus according to the present invention, and FIG. 2 is a plan view of the microwave antenna and the microwave plasma processing apparatus shown in FIG. In this microwave plasma processing apparatus, a microwave introduction window is opened on the top of a bottomed cylindrical reactor 1a formed entirely of aluminum, and this microwave introduction window is formed by a sealing plate 4 (sealed). Sealing member) in an airtight state. The sealing plate 4 is made of a dielectric material such as quartz glass or alumina that has heat resistance and microwave transparency and has a low dielectric loss.

An antenna 10 a is attached to the sealing plate 4. The antenna 10a includes a cover portion 17a (first side surface) covering the sealing plate 4, an outer wall portion 12a (second side surface), an inner wall portion 13a (second side surface), and an upper lid 23a (third side surface). The cover portion 17a, the outer wall portion 12a, the inner wall portion 13a, and the upper lid 23a constitute an annular waveguide antenna portion 11a (first tubular portion) capable of propagating microwaves therein.
Among these, the cover part 17a, the outer side wall part 12a, and the inner side wall part 13a are cut out from the aluminum block, and are manufactured integrally.

In the cover portion 17a, a plurality of openings 15a, 15a,... For taking out microwaves from the annular waveguide antenna portion 11a are formed in a strip shape in the diameter direction of the annular waveguide antenna portion 11a. .
The cover portion 17a, the outer wall portion 12a, and the inner wall portion 13a are manufactured as a single unit as described above, and are manufactured separately, so that they are not separated easily such as welding, brazing, and press fitting. The method may be integrated.

  The outer wall portion 12a and the inner wall portion 13a are provided concentrically with the central axis of the reactor 1a, and microwaves are introduced into the annular waveguide antenna portion 11a around the introduction port provided in the outer wall portion 12a. An introduction portion 16a (second tubular portion) is connected so as to be in the diameter direction of the annular waveguide antenna portion 11a. A dielectric 14 such as a fluororesin such as Teflon (registered trademark), a polyethylene resin, or a polystyrene resin (preferably Teflon) is fitted in the introduction portion 16a and the annular waveguide antenna portion 11a.

  FIG. 3A is an enlarged cross-sectional view around the upper lid 23a. The cover portion 17a, the outer wall portion 12a, the inner wall portion 13a, and the upper lid 23a are made of aluminum having good electrical conductivity in order to suppress the loss of microwaves. The upper lid 23a is made of an outer wall portion with a screw 36a. It is attached to 12a and the inner wall part 13a. The screw 36a is made of stainless steel in consideration of durability.

  On the other hand, the temperature of the cover portion 17a, the outer wall portion 12a, the inner wall portion 13a, and the upper lid 23a changes within a considerable range by heating with plasma, heating with a heater (not shown), and cooling with radiation. Therefore, expansion and contraction of each member occurs, but due to the difference in thermal expansion coefficient between aluminum and stainless steel, distortion occurs in the cover portion 17a, the outer wall portion 12a, the inner wall portion 13a, the upper lid 23a, and the screw 36a. Distortion accumulates. When the strain is accumulated, the positional relationship between the outer wall portion 12a and the inner wall portion 13a and the upper lid 23a may be shifted, or a gap may be opened between the two, and the impedance changes accordingly. Such inconveniences occur.

Therefore, the cover portion 17a, the outer wall portion 12a, and the inner wall portion 13a are integrally manufactured, and the upper lid 23a is attached to the screw 36a. However, this brings about the following advantages.
(1) The length of the screw 36a can be shortened, and the distortion caused by the difference in thermal expansion coefficient between aluminum and stainless steel can be reduced.
(2) The screw 36a stop position can be set to the microwave waveguide side from the center of each width of the outer wall portion 12a and the inner wall portion 13a, and the outer wall portion 12a, the inner wall portion 13a, the upper lid 23a, Can be made stronger on the microwave waveguide side, and a change in impedance due to thermal strain can be prevented.

(3) As shown in FIG. 3B, the contact portions between the outer wall portion 12c and the inner wall portion 13c and the upper lid 23a are more microscopic than the centers of the respective widths of the outer wall portion 12c and the inner wall portion 13c. Only the wave waveguide side can be provided, and the coupling between the outer wall portion 12c and the inner wall portion 13c and the upper lid 23a can be strengthened, and a change in impedance due to thermal strain can be prevented.
(4) Since the cover portion 17a, the outer wall portions 12a, c, and the inner wall portions 13a, c are integrated, it is possible to prevent changes in impedance due to thermal distortion, maintenance, and the like.

  On the waveguide deviated plane (E surface) of the connection portion (introduction port) between the annular waveguide antenna portion 11a and the introduction portion 16a, a micro structure having the same waveguide structure as that of the introduction portion 16a. A wave matching device 30 (E tuner) is provided so as to be perpendicular to the introduction portion 16a as shown in a plan view and a side sectional view of the antenna 10a in FIG. 4 (the cover portion 17a is omitted).

The microwave matching unit 30 has a variable position in the waveguide and has a short-circuit plate 31 for adjusting the impedance of the waveguide. The short-circuit plate 31 is connected to a drive unit 33 via a support bar 32. To adjust its position.
As shown in FIG. 5, the movable origin of the short-circuit plate 31 is 26 mm (offset) from the surface of the dielectric 14, and moves in a direction away from the surface of the dielectric 14. The inner cross section of the microwave matching unit 30 has a long side of 96 mm and a short side of 27 mm, the movable range of the short-circuit plate 31 is 0 to 80 mm, and the long side is arranged so as to be orthogonal to the microwave traveling direction.

  A waveguide 21 extending from the microwave oscillator 20 is connected to the introduction portion 16a. A directional coupler 35 is attached to the waveguide 21, and the directional coupler 35 detects the amount of microwave reflection from the connection portion between the annular waveguide antenna portion 11a and the introduction portion 16a. The detection signal is given to the control unit 34. The control unit 34 feedback-controls the driving unit 33 described above based on the given detection signal, and controls the position of the short-circuit plate 31 so that the amount of reflected microwaves is minimized.

  The microwave oscillated by the microwave oscillator 20 is incident on the introduction portion 16a of the antenna 10a through the waveguide 21. This incident wave is introduced from the introduction portion 16a into the annular waveguide antenna portion 11a. The microwaves introduced into the annular waveguide antenna unit 11a travel through the dielectric 14 in the annular waveguide antenna unit 11a as traveling waves traveling in the opposite directions to the annular waveguide antenna unit 11a. Both propagating waves propagate and collide at a position facing the inlet of the annular waveguide antenna portion 11a to generate a standing wave. By this standing wave, a current having a maximum value flows through the inner surface of the annular waveguide antenna portion 11a at a predetermined interval.

  At this time, in order to change the mode of the microwave propagating in the annular waveguide antenna unit 11a to the rectangular TE10 which is the basic propagation mode, the annular waveguide antenna unit 12a according to the microwave frequency of 2.45 GHz. These dimensions are 27 mm in height and 70 mm in width. The microwave in this mode propagates through the dielectric 14 in the annular waveguide antenna portion 11a with almost no energy loss.

  Further, when the sealing plate 4 having a diameter of 400 mm and a thickness of 27 mm is used and Teflon (registered trademark) having a relative dielectric constant εr = 2.1 is fitted into the annular waveguide antenna portion 11a, the annular waveguide type The dimension from the center of the antenna portion 11a to the center in the width direction of the annular waveguide antenna portion 11a is 370 mm. In this case, the circumferential length of the circle connecting the center in the width direction of the annular waveguide antenna portion 11a is substantially an integral multiple of the wavelength of the microwave propagating in the annular waveguide antenna portion 11a. Therefore, the microwave resonates in the annular waveguide antenna unit 11a, and the standing wave described above becomes high voltage / low current at the antinode position and low voltage / high current at the node position, and the antenna 10a. Q value is improved.

  Each of the openings 15a, 15a,... Is located approximately at the center between a plurality of strong electric field strength regions, and a strong electric field strength leaks from each of the openings 15a, 15a,. 4 is introduced into the reactor 1a. That is, a microwave that generates plasma is introduced into the reactor 1a.

A through hole penetrating the side wall is formed in the side wall of the reactor 1a, and a required gas is introduced into the processing chamber 2a of the reactor 1a from the gas inlet 22 fitted in the through hole. In the center of the bottom wall of the processing chamber 2a, a mounting table 3 on which the sample W is mounted is provided, and a high-frequency power source 7 is connected to the mounting table 3 via a matching box 6.
The distance between the mounting table 3 and the sealing plate 4 described above is 120 mm. In addition, an exhaust port 8 is formed in the bottom wall of the reactor 1a, and the inside air of the processing chamber 2 is discharged from the exhaust port 8.

  In order to perform an etching process on the surface of the sample W using such a microwave plasma processing apparatus, the processing chamber 2a is evacuated from the exhaust port 8 to a desired pressure, and then the processing chamber is connected to the processing chamber 2a. A reactive gas is supplied into 2a. Next, a microwave is oscillated from the microwave oscillator 20 and introduced into the antenna 10a through the waveguide 21 to form a standing wave there. This standing wave is introduced into the processing chamber 2a through the openings 15a, 15a,... Of the antenna 10a and the sealing plate 4, and plasma is generated in the processing chamber 2a. Etch.

  At this time, the directional coupler 35 detects the amount of microwave reflection from the connection portion between the annular waveguide antenna portion 11 a and the introduction portion 16 a and gives the detection signal to the control portion 34. The control unit 34 feedback-controls the driving unit 33 based on the given detection signal, and controls the position of the short-circuit plate 31 of the microwave matching unit 30 so that the amount of reflected microwaves is minimized.

6 and 7 are graphs showing the effect of adding the microwave matching device 30 to the connection portion between the annular waveguide antenna portion 11a and the introduction portion 16a. The voltage reflection coefficient | Γ | with respect to the position of the short-circuit plate 31 of the microwave matching device 30 when the process plasma was generated in the processing chamber 2 a was calculated from the detection value of the directional coupler 35.
Here, the plasma generation conditions in FIG. 6 are as follows: the gas type is argon, and the pressure is 5.33 Pa. The microwave power is 1 kW. In FIG. 7, the gas type is a mixed gas of C ₄ F ₈ / CO / O ₂ / Ar, and the pressure is 5.33 Pa.s. The microwave power is 2 kW.

As can be seen from the graph, in the annular antenna with a microwave matching unit (E tuner), the voltage reflection coefficient Γ changes with a minimum value by changing the position of the shorting plate of the microwave matching unit. . In particular, in the case of argon plasma, when the position of the short-circuit plate is 25 mm (the distance from the antenna dielectric surface is 51 mm), the reflection is substantially zero. That is, the reflected power is suppressed, and multiple reflections between the antenna and the microwave oscillator are suppressed.
Therefore, energy loss due to multiple reflection of microwaves can be suppressed as much as possible, and microwaves can be efficiently supplied to the plasma through the aperture while propagating the microwaves in the antenna circumferential direction. On the other hand, in the conventional microwave plasma apparatus, it is difficult to reduce the voltage reflection coefficient even if the microwave matching unit is adjusted.

  In this microwave plasma processing apparatus, matching can be satisfactorily performed without providing a tuner such as a stub between the microwave oscillator and the antenna, unlike the conventional microwave plasma processing apparatus. Of course, by providing a tuner between the microwave oscillator and the antenna, for example, even when the plasma processing conditions are largely changed, matching can be satisfactorily performed over a wider load range.

  In this microwave plasma processing apparatus, the microwave matching unit 30 (E) is disposed on the waveguide deviated plane (E plane) of the connection portion (introduction port) between the annular waveguide antenna portion 11a and the introduction portion 16a. A tuner is provided, but a microwave matching unit may be provided within the range of the length of the inside and outside of one wavelength of the microwave from the connecting portion. Even by providing a microwave matching device within a range of a length corresponding to one wavelength of the microwave from a connection portion having a largely different shape of the waveguide, reflection of the microwave at the connection portion is effectively suppressed. It is possible.

FIG. 8A shows an example of an antenna in which a microwave matching unit 30 (E tuner) is provided on a deviated plane (E plane) of the introduction portion 16a that is one wavelength (λg) away from the connection portion. It is a top view.
FIG. 8B is a plan view showing an example of an antenna in which microwave matching units 30 (E tuners) are provided at two locations on the upper lid 23a that is one wavelength (λg) away from the connection portion.
These antennas can also effectively suppress the reflection of microwaves from the connection portion.

Embodiment 2. FIG.
9 is a side sectional view showing the structure of the microwave antenna and microwave plasma processing apparatus according to the present invention, and FIG. 10 is a plan view of the microwave antenna and microwave plasma processing apparatus shown in FIG. In this microwave plasma processing apparatus, an antenna 10 b is attached to the sealing plate 4. The antenna 10b includes a cover portion 17b (first side surface), an outer wall portion 12b (second side surface), an inner wall portion 13b (second side surface), and an upper lid 23b (third side surface) that cover the sealing plate 4. The cover portion 17b, the outer wall portion 12b, the inner wall portion 13b, and the upper lid 23b constitute an annular waveguide antenna portion 11b (first tubular portion) capable of propagating microwaves therein.

Among these, the cover part 17b, the outer side wall part 12b, and the inner side wall part 13b are cut out from the aluminum block, and are manufactured integrally.
In the cover portion 17b, a plurality of openings 15a, 15a,... For taking out the microwaves from the annular waveguide antenna portion 11b are formed in a strip shape in the diameter direction of the annular waveguide antenna portion 11b. .

  The outer wall portion 12b and the inner wall portion 13b are provided concentrically with the central axis of the reactor 1a, and the microwave is introduced to the annular waveguide antenna portion 11b around the introduction port provided in the outer wall portion 12b. An introduction portion 16b (second tubular portion) is connected so as to be in the diameter direction of the annular waveguide antenna portion 11b. A dielectric 14 such as a fluororesin such as Teflon (registered trademark), a polyethylene resin, or a polystyrene resin (preferably Teflon) is fitted in the introduction portion 16b and the annular waveguide antenna portion 11b.

  The surface (H surface) of the inner side wall portion 13b facing the connection portion (introduction port) between the annular waveguide antenna portion 11b and the introduction portion 16b has a waveguide structure similar in cross section to the introduction portion 16b. A certain microwave matching device 40 (H tuner) is provided so as to be perpendicular to the introduction portion 16b as shown in a plan view and a side sectional view of the antenna 10b in FIG. 11 (the cover member 17b is omitted).

The microwave matching unit 40 has a variable position in the waveguide and has a short-circuit plate 41 for adjusting the impedance of the waveguide. The short-circuit plate 41 is connected to the drive unit 43 via the support rod 42. To adjust its position.
As shown in FIG. 12, the driving origin of the short-circuit plate 41 is 53 mm (offset) from the surface of the dielectric 14, and is movable in a direction away from the surface of the dielectric 14. The inner cross section of the microwave matching unit 40 is 96 mm long and 27 mm short, and the movable range of the short-circuit plate 41 is 0 to 80 mm.

  A waveguide 21 extending from the microwave oscillator 20 is connected to the introduction portion 16b. A directional coupler 35 is attached to the waveguide 21, and the directional coupler 35 detects the amount of microwave reflection from the connection portion between the annular waveguide antenna portion 11 b and the introduction portion 16 b. The detection signal is given to the control unit 44. The controller 44 controls the position of the short-circuit plate 41 so as to minimize the amount of reflected microwaves by feedback-controlling the drive unit 43 described above based on the given detection signal.

  The microwave oscillated by the microwave oscillator 20 is incident on the introduction portion 16b of the antenna 10b through the waveguide 21. This incident wave is introduced from the introduction portion 16b to the annular waveguide antenna portion 11b. The microwaves introduced into the annular waveguide antenna unit 11b travel through the dielectric 14 in the annular waveguide antenna unit 11b as traveling waves traveling in opposite directions to each other through the annular waveguide antenna unit 11b. Both propagating waves propagate and collide at a position facing the introduction port of the annular waveguide antenna portion 11b to generate a standing wave. By this standing wave, a current having a maximum value flows at a predetermined interval on the inner surface of the annular waveguide antenna portion 11b. Since the other structure is the same as the structure of the microwave plasma processing apparatus of the above-described embodiment, the same portions are denoted by the same reference numerals and description thereof is omitted.

  In order to perform an etching process on the surface of the sample W using such a microwave plasma processing apparatus, the processing chamber 2a is evacuated from the exhaust port 8 to a desired pressure, and then the processing chamber is connected to the processing chamber 2a. A reactive gas is supplied into 2a. Next, a microwave is oscillated from the microwave oscillator 20 and introduced into the antenna 10b through the waveguide 21 to form a standing wave there. This standing wave is introduced into the processing chamber 2a through the openings 15a, 15a,... Of the antenna 10b and the sealing plate 4, and plasma is generated in the processing chamber 2a. Etch.

  At this time, the directional coupler 35 detects the amount of microwave reflection from the connection portion between the annular waveguide antenna portion 11 b and the introduction portion 16 b, and gives the detection signal to the control portion 44. The control unit 44 performs feedback control of the driving unit 43 based on the given detection signal, and controls the position of the short-circuit plate 41 of the microwave matching unit 40 so that the amount of reflected microwaves is minimized.

  In this microwave plasma processing apparatus, matching can be satisfactorily performed without providing a tuner such as a stub between the microwave oscillator and the antenna as in the conventional apparatus. Of course, by providing a tuner between the microwave oscillator and the antenna, for example, even when the plasma processing conditions are largely changed, matching can be satisfactorily performed over a wider load range.

  In this microwave plasma processing apparatus, the microwave matching unit 40 (on the surface (H surface) of the inner side wall 13 b facing the connection portion (introduction port) between the annular waveguide antenna portion 11 b and the introduction portion 16 b is provided. (H tuner) is provided, but a microwave matching unit may be provided within the range of the length of the inside and outside of one wavelength of the microwave from the connection portion. Even by providing a microwave matching device within a range of a length corresponding to one wavelength of the microwave from a connection portion having a largely different shape of the waveguide, reflection of the microwave at the connection portion is effectively suppressed. It is possible.

FIG. 13A shows an example of an antenna in which a microwave matching unit 40 (H tuner) is provided on the vertical plane (H plane) of the introduction section 16b that is one wavelength (λg) away from the connection section. It is a top view.
FIG. 13B is a plan view showing an example of an antenna in which microwave matching units 40 (H tuners) are provided at two locations on the inner wall 13b that is one wavelength (λg) away from the connection portion.
These antennas can also effectively suppress the reflection of microwaves from the connection portion.

  In the first and second embodiments, the former uses one microwave matching unit 30 (E tuner) for the annular waveguide antenna unit 11a, and the latter uses the microwave matching unit 40 (H tuner). ) Is used for the annular waveguide antenna portion 11b. As shown in the plan view and the side sectional view of the antenna 10c in FIG. 14, the annular waveguide antenna portion 11c and the introduction portion 16c A microwave matching unit 30 (E tuner) is provided on the waveguide deviated plane (E surface) of the connection part (introduction port) so as to be perpendicular to the introduction part 16c, and introduced into the annular waveguide antenna part 11c. Even if the microwave matching device 40 (H tuner) is provided at a right angle to the introduction portion 13c on the surface (H surface) of the inner wall 13b facing the connection portion (introduction port) with the portion 16c, the same effect is obtained. Can be obtained. Furthermore, the antenna configurations shown in FIGS. 4, 8, 11, 13, and 14 may be freely selected and combined.

Further, when there are a plurality of connection portions (introduction ports) between the annular waveguide antenna portion and the introduction portion, the same effect can be obtained by providing a microwave matching device for each.
In the first and second embodiments described above, the microwave matching unit uses a type in which the position of the short-circuit plate is variable. However, a type in which the insertion amount of the conductor rod into the waveguide is variable is used. However, the same effect can be obtained.

  Further, as shown in FIG. 15, a connection portion (introduction port) between the annular waveguide antenna portion 11d and the introduction portion 16d is provided on the upper lid of the annular waveguide antenna portion 11d, and the introduction portion 16d is provided on the upper lid. Even in the case of being provided vertically, by providing the microwave matching device 50 in the vicinity of the connection portion, reflection of the microwave from the connection portion can be effectively suppressed.

It is a sectional side view which shows the structure of the microwave antenna and microwave plasma processing apparatus which concern on this invention. It is a top view of the microwave antenna and microwave plasma processing apparatus which were shown in FIG. It is an expanded sectional view of the upper cover periphery. It is the top view and side sectional view of an antenna. It is a sectional side view which shows the structure of a microwave matching device. It is a graph which shows the effect by having added the microwave matching device to the connection part of an annular waveguide type antenna part and an introduction part. It is a graph which shows the effect by having added the microwave matching device to the connection part of an annular waveguide type antenna part and an introduction part. It is a top view which shows the example of the antenna which provided the microwave matching device in the position separated 1 wavelength of the microwave from the connection part. It is a sectional side view which shows the structure of the microwave antenna and microwave plasma processing apparatus which concern on this invention. It is a top view of the microwave antenna and microwave plasma processing apparatus which were shown in FIG. It is the top view and side sectional view of an antenna. It is a sectional side view which shows the structure of a microwave matching device. It is a top view which shows the example of the antenna which provided the microwave matching device in the position separated 1 wavelength of the microwave from the connection part. It is the top view and side sectional view of an antenna. FIG. 5 is a side sectional view showing a case where a connecting portion between an annular waveguide antenna portion and an introduction portion is provided on the upper lid of the annular waveguide antenna portion, and the introduction portion is provided perpendicular to the upper lid. It is a sectional side view which shows the structure of the conventional microwave plasma processing apparatus. It is a top view which shows the structure of the conventional microwave plasma processing apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1a Reactor 2a Processing chamber 3 Mounting stand 4 Sealing plate (sealing member)
10a, 10b, 10c Antennas 11a, 11b, 11c, 11d Annular waveguide antenna part (first tubular part)
12a, 12b, 12c Outer side wall (second side surface)
13a, 13b, 13c Inner side wall (second side surface)
14 Dielectric 15a Opening 16a, 16b, 16c, 16d Introduction part (second tubular part)
17a, 17b Cover (first side)
20 Microwave Oscillator 21 Waveguide 22 Gas Inlet 23a, 23b Upper Cover (Third Side)
30 Microwave matcher (E tuner)
31, 41 Short-circuit plate 32, 42 Support rod 33, 43 Drive unit 34, 44 Control unit 35 Directional coupler (detector)
36a Screw 40 Microwave matcher (H tuner)
50 Microwave matcher W Sample

Claims (5)

An annular first tubular portion for propagating microwaves, one or a plurality of introduction ports opened on a side surface of the first tubular portion for introducing microwaves into the first tubular portion, and connected to the introduction port A microwave having a second tubular part for supplying microwaves into the first tubular part, and a plurality of openings provided in the first tubular part for extracting microwaves from the first tubular part In the antenna
The first tubular portion is formed by integrally forming a first side surface in which the opening is formed and two second side surfaces that are orthogonal to the first side surface and that are opposed to each other, and that are orthogonal to the second side surface. Is attached to the second side surface in a detachable manner. The third aspect is attached by a plurality of screws to the walls forming the second aspect, the mounting position of the screw, according to claim 1 wherein the inboard of said first tubular portion from the center of the thickness of the wall Microwave antenna. Wherein the second side face forms a wall between the third side surface, the outside direction of the first tubular portion, the microwave antenna according to claim 1 or 2 wherein has a space for no contact. A microwave that introduces a microwave through a portion of the sealing member that is sealed with a sealing member, generates a plasma with the microwave, and processes an object to be processed with the generated plasma. In wave plasma processing equipment,
Comprising a microwave antenna according to any one of claims 1 to 3, the microwave plasma processing apparatus, wherein the opening of the microwave antenna is opposed to the sealing member. The microwave plasma processing apparatus according to claim 4 , wherein a portion of the microwave antenna that forms the first side surface where the opening is formed is configured to cover the sealing member so that the microwave does not leak to the outside.

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