JP2013109875A - Micro wave plasma processing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a micro wave plasma processing apparatus which can easily perform a predetermined modification treatment regardless of the geometry of a target face of an object to be processed.SOLUTION: The micro wave plasma processing apparatus 1 comprises: an inner cylindrical part 30; an outer cylindrical part 31; a waveguide 33 disposed between the inner and outer cylindrical parts 30 and 31; a slit 36 which communicates to the waveguide 33, and is narrower in width than the waveguide 33 in a direction perpendicular to an axis of the cylindrical part; and a gas supply part 35 for supplying a plasma-generation gas to the slit 36.

Description

  The present invention relates to a microwave plasma processing apparatus that generates a plasma by a microwave under a substantially atmospheric pressure condition and performs a predetermined surface modification process on a processing object by the plasma.

  Patent Document 1 discloses a microwave plasma processing apparatus capable of modifying the outer peripheral surface of a processing object. The microwave plasma processing apparatus described in the document includes an outer cylinder and two inner cylinders. The two inner cylinders are arranged in series in the axial direction via a ring-shaped slit. The outer cylinder is disposed on the radially outer side of the two inner cylinders. Plasma is generated near the slit. On the other hand, the processing object passes in the axial direction on the radially inner side of the two inner cylinders. When the processing object passes through the inside of the slit in the radial direction, the outer peripheral surface of the processing object is irradiated with plasma. A predetermined modification process is performed on the outer peripheral surface by plasma irradiation.

  According to the microwave plasma processing apparatus described in this document, it is easy to perform a modification process on the outer peripheral surface of a cylindrical or columnar processing target. However, it is difficult to perform the modification treatment on the planar surface of the film-like or plate-like treatment object.

  In this regard, Patent Document 2 discloses a plasma processing apparatus having a cylindrical discharge space. The plasma processing apparatus described in the document includes a columnar first electrode, a cylindrical second electrode, and a cylindrical dielectric member. The dielectric member is wrapped around the outer peripheral surface of the first electrode. The second electrodes are arranged on the outer side in the radial direction of the dielectric member and spaced apart by a predetermined interval. A discharge space is defined between the dielectric member and the second electrode. Plasma is generated in the discharge space. A process gas is supplied to the discharge space. In the discharge space, the process gas is activated by the plasma. The activated process gas (hereinafter referred to as “active gas”) is ejected in the axial direction from the tip of the plasma processing apparatus. On the other hand, the plate-like processing object is disposed to face the tip of the plasma processing apparatus. A predetermined modification process is performed on the surface of the object to be processed by the active gas sprayed from the tip.

  According to the plasma processing apparatus described in the document, it is easy to perform a modification process on a planar surface of a film-like or plate-like treatment object. However, it is difficult to perform the reforming process on the outer peripheral surface of the cylindrical or columnar processing target.

JP 2010-129327 A JP 2009-272165 A

  Thus, the microwave plasma processing apparatus of Patent Document 1 is dedicated to the outer peripheral surface, and the plasma processing apparatus of Patent Document 2 is dedicated to the planar surface. For this reason, both are lacking in versatility.

  Even if a combination of the microwave plasma processing apparatus disclosed in Patent Document 1 and the plasma processing apparatus disclosed in Patent Document 2 is attempted, the processing methods of both plasma processing apparatuses are fundamentally different. That is, the microwave plasma processing apparatus of Patent Document 1 performs surface modification processing on a processing target by irradiating the processing target with plasma itself. On the other hand, the plasma processing apparatus of Patent Document 2 performs a surface modification process on a processing object by irradiating the processing object with an active gas activated by plasma. Thus, the microwave plasma processing apparatus of Patent Document 1 uses plasma “directly” for processing, whereas the plasma processing apparatus of Patent Document 2 uses plasma “indirectly” for processing. For this reason, it is difficult to combine both plasma processing apparatuses. Note that the plasma processing apparatus of Patent Document 2 is less likely to obtain a high surface modification effect by the amount not directly using plasma.

  The microwave plasma processing apparatus of the present invention has been completed in view of the above problems. An object of this invention is to provide the microwave plasma processing apparatus which is easy to perform a predetermined | prescribed modification process irrespective of the shape of the process target surface of a process target object.

  (1) In order to solve the above-described problems, a microwave plasma processing apparatus of the present invention includes an inner cylinder part, an outer cylinder part arranged on the axially outer side of the inner cylinder part, the inner cylinder part and the outer cylinder part. A waveguide path that is disposed between the cylindrical portion and in which microwaves propagate in the axial direction, and is disposed between one axial end of the inner cylindrical portion and one axial end of the outer cylindrical portion; And a gas supply section that supplies a plasma generating gas to the slit, and the microwave and the plasma are generated under substantially atmospheric pressure conditions. By passing the working gas through the slit, the electric field of the microwave is concentrated to form a high electric field in the vicinity of the slit, the plasma generating gas is ionized by the high electric field to generate plasma, and the plasma is irradiated By performing a predetermined reforming process on the processing target surface of the processing target And characterized by applying. Here, the “axial direction” refers to a direction substantially orthogonal to the axial direction.

  According to the microwave plasma processing apparatus of the present invention, the slit is disposed between the one axial end of the inner cylindrical portion and the one axial end of the outer cylindrical portion. Plasma is generated near the slit. For this reason, by arranging the processing target surface of the processing target in the vicinity of the slit and irradiating the processing target surface with plasma, the processing target surface can be subjected to a predetermined modification process.

  Moreover, according to the microwave plasma processing apparatus of the present invention, the plasma irradiation direction is adjusted by adjusting the axial positional relationship between the axial end of the inner cylindrical portion and the axial end of the outer cylindrical portion. Can do.

  That is, when the axial end of the inner cylinder part and the axial end of the outer cylinder part are aligned in the axial direction when viewed from the axially outer side or the axially inner side, the slit faces only the axially outer side. . For this reason, the plasma irradiation direction can be directed outward in the axial direction. Therefore, by disposing the processing target surface of the processing target object on the outer side in the axial direction of the slit, the processing target surface can be subjected to a predetermined modification process.

  Further, when one axial end of the inner cylinder portion is disposed on the inner side in the axial direction with respect to one axial end of the outer cylinder portion when viewed from the axially outer side or the axial direction inner side, the slits are axially outer and axially straight. Turn inward. For this reason, the plasma irradiation direction can be directed to the outside in the axial direction and the inside in the axial direction. Therefore, a predetermined modification process can be performed on the processing target surface by disposing the processing target surface of the processing target on the axially outer side and the axially straight side of the slit. In addition, the plasma irradiation direction can be finely adjusted by adjusting the amount of deviation between the axial end of the inner cylinder and the axial end of the outer cylinder.

  On the other hand, when one axial end of the inner cylinder portion is disposed on the axial outer side with respect to the axial one end of the outer cylinder portion when viewed from the axially outer side or the axially inner side, Directly outward. For this reason, the direction of plasma irradiation can be directed outward in the axial direction and outward in the axial direction. Therefore, by arranging the processing target surface of the processing target object on the outer side in the axial direction and the outer side in the axial direction of the slit, it is possible to perform a predetermined reforming process on the processing target surface. In addition, the plasma irradiation direction can be finely adjusted by adjusting the amount of deviation between the axial end of the inner cylinder and the axial end of the outer cylinder.

  As described above, according to the microwave plasma processing apparatus of the present invention, the plasma irradiation direction can be freely adjusted by adjusting the axial positional relationship between the axial end of the inner cylindrical portion and the axial end of the outer cylindrical portion. Can be adjusted. For this reason, it is easy to perform a predetermined reforming process regardless of the shape of the processing target surface of the processing target.

  Further, according to the microwave plasma processing apparatus of the present invention, plasma is not accelerated by an electric field or the like during plasma irradiation. For this reason, it is difficult for plasma to roughen the surface to be processed.

  In addition, according to the microwave plasma processing apparatus of the present invention, the slit has a narrower axial width than the waveguide. For this reason, when the microwave is introduced from the waveguide path into the slit, the cross-sectional area of the path is reduced. Accordingly, the electric field strength of the microwave can be increased in the vicinity of the slit. Therefore, the plasma generating gas can be reliably ionized even under reduced pressure conditions, in other words, under substantially atmospheric pressure conditions. Thus, according to the microwave plasma processing apparatus of the present invention, a vacuum facility is unnecessary. For this reason, the equipment structure is simple.

  Further, according to the microwave plasma processing apparatus of the present invention, the microwave propagates through the waveguide (space) instead of the dielectric substrate. For this reason, a dielectric substrate is unnecessary. Therefore, according to the microwave plasma processing apparatus of the present invention, the equipment structure is simplified.

  In addition, according to the microwave plasma processing apparatus of the present invention, it is not necessary to align (align) the two inner cylinders as compared with the microwave plasma processing apparatus of Patent Document 1. Also in this respect, the equipment structure is simplified.

  (1-1) Preferably, in the configuration of the above (1), the slit is arranged in a portion corresponding to a multiple of the wavelength of the microwave (including 1/2 wavelength and 1/4 wavelength). Is better.

  According to this configuration, the slit is arranged at a portion where the resonance phenomenon due to the standing wave occurs. For this reason, the electric field strength of the microwave can be further increased. Further, plasma can be generated even when the input power of the microwave is small.

  Moreover, according to this structure, compared with the microwave plasma processing apparatus of patent document 1, the position of a slit can be adjusted by adjusting the axial direction length of an inner cylinder part and an outer cylinder part. This simplifies the equipment structure.

  (1-2) Preferably, in the configuration of the above (1), the outer cylinder portion may have a tapered portion that decreases in diameter toward the slit. According to this configuration, the microwave irradiation area can be reduced.

  (1-3) Preferably, in the configuration of the above (1), the inner cylinder portion may have a reverse taper portion whose diameter increases toward the slit. According to this configuration, the microwave irradiation area can be increased.

  (2) Preferably, in the configuration of the above (1), the processing target surface is movable relative to the slit, and the slit extends in an endless annular shape in the circumferential direction. Is better. According to this configuration, it is possible to perform processing at a time on a portion occupying a large area in the processing target surface. For this reason, the processing efficiency is improved.

  (3) Preferably, in the configuration of (1) or (2) above, the inner cylindrical portion and the outer cylindrical portion are substantially similar to each other in outer shape in a cross section perpendicular to the axis, and are arranged substantially coaxially. It is better to have a configuration. According to this configuration, the waveguides can be arranged substantially evenly between the inner cylinder part and the outer cylinder part. For this reason, it can suppress that plasma becomes non-uniform | heterogenous by the position of a slit.

  ADVANTAGE OF THE INVENTION According to this invention, the microwave plasma processing apparatus which is easy to perform a predetermined | prescribed modification process can be provided irrespective of the shape of the process target surface of a process target object.

It is a permeation | transmission perspective view of the microwave plasma processing apparatus of 1st embodiment. It is sectional drawing of the front-back direction of the same microwave plasma processing apparatus. FIG. 3 is an enlarged view in a frame III in FIG. 2. It is an expanded sectional view near the slit of the microwave plasma processing apparatus of a second embodiment. It is an expanded sectional view near the slit of the microwave plasma processing apparatus of a third embodiment. It is an expanded sectional view near the slit of the microwave plasma processing apparatus of a fourth embodiment.

  Hereinafter, embodiments of the microwave plasma processing apparatus of the present invention will be described.

<First embodiment>
[Configuration of microwave plasma processing equipment]
First, the configuration of the microwave plasma processing apparatus of this embodiment will be described. The microwave plasma processing apparatus of the present embodiment performs a reforming process on a planar processing target surface of a processing target under a substantially atmospheric pressure (= 1.013 × 10 ⁵ Pa or pressure near the pressure) condition. It is something to apply.

  FIG. 1 is a transparent perspective view of the microwave plasma processing apparatus of this embodiment. FIG. 2 shows a cross-sectional view in the front-rear direction of the microwave plasma processing apparatus. As shown in FIGS. 1 and 2, the microwave plasma processing apparatus 1 according to the present embodiment includes a first waveguide 2 and a second waveguide 3.

  The first waveguide 2 includes a rectangular tube part 20, a plunger 21, a holding part 22, and a first waveguide path 23. The rectangular tube portion 20 is made of metal. The rectangular tube portion 20 extends in the front-rear direction. An inner cylinder holding hole 200 is formed in the lower wall of the rectangular cylinder 20. An outer cylinder part mounting hole 201 is formed in the upper wall of the square cylinder part 20. The inner cylinder part holding hole 200 and the outer cylinder part mounting hole 201 are opposed to each other in the vertical direction. The plunger 21 is made of metal and is inserted into the rectangular tube portion 20 from the front. The plunger 21 is movable in the front-rear direction. A first waveguide 23 is defined inside the rectangular tube portion 20. The length of the first waveguide path 23 in the front-rear direction can be adjusted by the plunger 21.

  As shown in FIG. 2, the microwave power source 90 generates microwaves. The pulse generator 95 modulates the output of the microwave. Specifically, the duty ratio of the output of the microwave power supply 90 is changed. Microwaves propagate through the first waveguide 23 from the microwave power source 90 through the incident side power monitor 91 → isolator 92 → reflection side power monitor 93 → matching unit 94.

  The holding | maintenance part 22 is metal, Comprising: The taper cylinder shape which sharpens toward the upper direction from the downward direction is exhibited. The holding portion 22 is erected from the upper surface (inner surface) of the lower wall of the rectangular tube portion 20. The holding part 22 is disposed at the mouth edge of the inner cylinder part holding hole 200.

  The second waveguide 3 includes an inner cylinder part 30, an outer cylinder part 31, a second waveguide path 33, a spacer 34, a gas supply part 35, and a slit 36. The second waveguide 33 is included in the concept of the “waveguide” of the present invention. The second waveguide 3 is connected to the first waveguide 2 at a substantially right angle.

  The inner cylinder portion 30 is made of metal and has a cylindrical shape. The inner cylinder part 30 is extended in the up-down direction. The lower end of the inner cylinder part 30 penetrates the outer cylinder part mounting hole 201 and the inner cylinder part holding hole 200 of the square cylinder part 20. That is, the lower end of the inner cylinder part 30 protrudes downward from the square cylinder part 20. The outer peripheral surface near the lower end of the inner cylinder part 30 is fixed by the inner peripheral edge of the inner cylinder part holding hole 200 and the holding part 22. Thus, the inner cylinder part 30 is fixed to the lower wall of the square cylinder part 20.

  The outer cylinder portion 31 is made of metal and has a cylindrical shape. The outer cylinder part 31 is disposed on the outer side in the radial direction (axial direction) of the inner cylinder part 30. The outer cylinder part 31 and the inner cylinder part 30 are arrange | positioned substantially coaxially. The lower end of the outer cylinder part 31 is attached to the rim of the outer cylinder part attachment hole 201 of the square cylinder part 20. That is, the outer cylinder part 31 is fixed to the upper wall of the square cylinder part 20. A gas supply part attachment hole 310 is formed in the outer cylinder part 31. A tapered portion 311 that is pointed from below to above is formed at the upper portion of the outer cylinder portion 31.

  The spacer 34 is made of a dielectric (for example, quartz, alumina, etc.) and has a ring shape. The spacer 34 is interposed between the outer peripheral surface of the inner cylindrical portion 30 and the inner peripheral surface of the outer cylindrical portion 31. The spacer 34 aligns the inner cylinder part 30 and the outer cylinder part 31 substantially coaxially.

  The gas supply unit 35 is made of stainless steel and has a tubular shape. The gas supply part 35 is attached to the edge of the gas supply part attachment hole 310 of the outer cylinder part 31. Helium gas flows inside the gas supply unit 35. Helium gas is included in the concept of “plasma generating gas” of the present invention.

  The second waveguide 33 is defined between the inner peripheral surface of the outer cylindrical portion 31 and the outer peripheral surface of the inner cylindrical portion 30. That is, the space that forms the second waveguide 33 has a cylindrical shape. The second waveguide 33 is connected to the first waveguide 23 at a substantially right angle via the outer tube portion mounting hole 201.

  FIG. 3 shows an enlarged view in the frame III of FIG. As shown in FIG. 3, the slit 36 is disposed between the upper end (one axial end) of the inner cylindrical portion 30 and the upper end (one axial end) of the outer cylindrical portion 31 (specifically, the tapered portion 311). Has been. The slit 36 communicates with the second waveguide 33. The slit 36 is disposed in a portion corresponding to a multiple of the microwave wavelength (including ½ wavelength and ¼ wavelength). The slit 36 has a ring shape extending in the circumferential direction. The radial width A1 of the slit 36 is smaller than the radial width A2 of the second waveguide 33. When viewed from the radially outer side or the radially inner side, the upper end of the inner cylinder part 30 is shifted downward (inward in the axial direction) from the upper end of the outer cylinder part 31 by a deviation amount A3. For this reason, the slit 36 faces upward and radially inward. Above the slit 36 and radially inward, a ring-shaped plasma P is generated as shown by dotted line hatching in FIG.

  The processing object 80 has a film shape. The processing target surface 800 has a planar shape. The processing target surface 800 is disposed above the slit 36. As shown in FIG. 2, the processing object 80 is movable in the horizontal direction with respect to the slit 36.

[Movement of microwave plasma processing equipment]
Next, the movement at the time of performing the surface modification process of the microwave plasma processing apparatus 1 of the present embodiment will be described. First, as shown in FIG. 2, the microwave power source 90 is turned on to generate microwaves. The microwave output is appropriately modulated by the pulse generator 95. The microwave is introduced into the first waveguide 23 through the incident-side power monitor 91 → isolator 92 → reflection-side power monitor 93 → matching device 94.

  At this time, the output of the generated microwave is monitored by the power monitor 91 on the incident side. Further, the output of the reflected microwave is monitored by the power monitor 93 on the reflection side. Further, the output of the reflected microwave is attenuated by the isolator 92. Further, the matching unit 94 adjusts the amount of reflected microwaves.

  Next, the microwave is introduced from the first waveguide 23 into the second waveguide 33. The introduced microwave propagates through the second waveguide 33 from the bottom to the top while penetrating the spacer 34. Subsequently, the microwave enters the slit 36. Here, the passage cross-sectional area (radial direction cross-sectional area) of the slit 36 is extremely smaller than the passage cross-sectional area (radial direction cross-sectional area) of the second waveguide 33. For this reason, when entering the slit 36 from the second waveguide 33, the electric field strength of the microwave becomes extremely high.

  On the other hand, helium gas is supplied from the gas supply unit 35 to the second waveguide 33 through the gas supply unit attachment hole 310. The helium gas enters the slit 36 together with the microwave. When passing through the slit 36, the helium gas is ionized by the high electric field of the microwave formed in the vicinity of the slit 36. Then, plasma P is generated above the slit 36 and radially inside.

  Then, while moving the processing object 80 in the horizontal direction, the processing target surface 800 is continuously irradiated with the plasma P as if it were scanned. In this way, the modification process is performed on the processing target surface 800.

[Function and effect]
Next, the effect of the microwave plasma processing apparatus 1 of this embodiment is demonstrated. According to the microwave plasma processing apparatus 1 of the present embodiment, the slit 36 is disposed between one axial end of the inner cylindrical portion 30 and one axial end of the outer cylindrical portion 31. The plasma P is generated near the slit 36. For this reason, the processing target surface 800 of the processing target 80 is disposed in the vicinity of the slit 36 and the processing target surface 800 is irradiated with the plasma P, whereby the processing target surface 800 can be subjected to a predetermined modification process.

  In addition, according to the microwave plasma processing apparatus 1 of the present embodiment, the irradiation of the plasma P is performed by adjusting the axial positional relationship between the axial end of the inner cylindrical portion 30 and the axial end of the outer cylindrical portion 31. The direction can be adjusted. Moreover, the irradiation direction of the plasma P can be finely adjusted by adjusting the amount of deviation A3 between the one axial end of the inner cylindrical portion 30 and the one axial end of the outer cylindrical portion 31. Thus, according to the microwave plasma processing apparatus 1 of the present embodiment, the plasma P is adjusted by adjusting the axial positional relationship between the axial end of the inner cylindrical portion 30 and the axial end of the outer cylindrical portion 31. The irradiation direction can be freely adjusted. For this reason, a predetermined modification process can be performed regardless of the shape of the processing target surface 800 of the processing target 80.

  Further, according to the microwave plasma processing apparatus 1 of the present embodiment, the plasma P is not accelerated by an electric field or the like during plasma irradiation. For this reason, it is difficult for the plasma P to roughen the processing target surface 800.

  Further, according to the microwave plasma processing apparatus 1 of the present embodiment, the radial width A1 of the slit 36 is smaller than the radial width A2 of the second waveguide 33. For this reason, when the microwave is introduced from the second waveguide 33 into the slit 36, the cross-sectional area of the passage is reduced. Therefore, the electric field strength of the microwave can be increased in the vicinity of the slit 36. Therefore, the plasma generating gas can be reliably ionized even under reduced pressure conditions, in other words, under substantially atmospheric pressure conditions. Thus, according to the microwave plasma processing apparatus 1 of this embodiment, a vacuum facility is unnecessary. For this reason, the equipment structure is simple.

  Further, according to the microwave plasma processing apparatus 1 of the present embodiment, the microwave propagates through the second waveguide 33 (space) instead of the dielectric substrate. For this reason, a dielectric substrate is unnecessary. Therefore, according to the microwave plasma processing apparatus 1 of the present embodiment, the equipment structure is simplified.

  The slit 36 is disposed at a portion corresponding to a multiple of the wavelength of the microwave (including a half wavelength and a quarter wavelength). That is, the slit 36 is arranged at a portion where the resonance phenomenon due to the standing wave occurs. For this reason, the electric field strength of the microwave can be further increased. Further, the plasma P can be generated even when the input power of the microwave is small.

  Moreover, according to the microwave plasma processing apparatus 1 of this embodiment, compared with the microwave plasma processing apparatus of patent document 1, by adjusting the axial direction length of the inner cylinder part 30 and the outer cylinder part 31, it is a slit. The position of 36 can be adjusted. This simplifies the equipment structure.

  In addition, according to the microwave plasma processing apparatus 1 of the present embodiment, the outer cylindrical portion 31 includes the tapered portion 311 that decreases in diameter toward the slit 36. For this reason, the microwave irradiation region can be reduced.

  Further, according to the microwave plasma processing apparatus 1 of the present embodiment, the processing target surface 800 can be moved relative to the slit 36. In addition, the slit 36 extends in an endless annular shape. For this reason, the reforming process can be performed at once on the portion of the processing target surface 800 that occupies a large area. For this reason, the efficiency of the reforming process is improved.

  Further, according to the microwave plasma processing apparatus 1 of the present embodiment, the inner cylinder part 30 and the outer cylinder part 31 are substantially similar in outer shape in radial cross section and are arranged substantially coaxially. For this reason, the second waveguide path 33 can be arranged substantially evenly between the inner cylinder part 30 and the outer cylinder part 31. Therefore, it is possible to suppress the plasma P from becoming nonuniform due to the circumferential position of the slit 36.

<Second embodiment>
The difference between the microwave plasma processing apparatus of the present embodiment and the microwave plasma processing apparatus of the first embodiment is that the object to be processed has a long-axis cylindrical shape. Here, only differences will be described.

  FIG. 4 shows an enlarged cross-sectional view near the slit of the microwave plasma processing apparatus of the present embodiment. In addition, about the site | part corresponding to FIG. 3, it shows with the same code | symbol. As shown in FIG. 4, the processing object 80 has a long-axis cylindrical shape. The processing object 80 passes from the lower side to the upper side through the radially inner side of the inner cylinder part 30. When the processing object 80 passes inside the slit 36 in the radial direction, the processing target surface 800 is irradiated with the plasma P. At this time, the reforming process is simultaneously performed on the entire processing target surface 800 on the entire circumference.

  The microwave plasma processing apparatus according to the present embodiment and the microwave plasma processing apparatus according to the first embodiment have the same operational effects with respect to the parts having the same configuration. As in the present embodiment, a long-axis cylindrical (or long-axis columnar) processing object 80 is inserted into the inner side of the inner cylinder portion 30 in the radial direction, and the processing target surface 800 that is the outer peripheral surface is continuously modified. A quality treatment may be applied.

<Third embodiment>
The difference between the microwave plasma processing apparatus of the present embodiment and the microwave plasma processing apparatus of the first embodiment is that the outer tube portion has a straight tube shape. And the inner cylinder part is a point provided with the reverse taper part. Here, only differences will be described.

  FIG. 5 shows an enlarged cross-sectional view near the slit of the microwave plasma processing apparatus of the present embodiment. In addition, about the site | part corresponding to FIG. 3, it shows with the same code | symbol. As shown in FIG. 5, the outer cylinder portion 31 has a straight tubular shape. In addition, an inverted tapered portion 301 is formed at the upper portion of the inner cylinder portion 30 so as to expand from below to above.

  The slit 36 is disposed between the upper end (one axial end) of the inner cylindrical portion 30 (specifically, the reverse tapered portion 301) and the upper end (one axial end) of the outer cylindrical portion 31. The slit 36 communicates with the second waveguide 33. The slit 36 has a ring shape extending in the circumferential direction. The radial width A1 of the slit 36 is smaller than the radial width A2 of the second waveguide 33. When viewed from the radially outer side or the radially inner side, the upper end of the inner cylinder part 30 is displaced upward (in the axially outer direction) from the upper end of the outer cylinder part 31 by a deviation amount A3. For this reason, the slit 36 faces upward and radially outward. Ring-shaped plasma P is generated above the slit 36 and outside in the radial direction, as indicated by dotted hatching in FIG.

  The microwave plasma processing apparatus according to the present embodiment and the microwave plasma processing apparatus according to the first embodiment have the same operational effects with respect to the parts having the same configuration. Further, according to the microwave plasma processing apparatus of the present embodiment, the inner cylindrical portion 30 includes the reverse tapered portion 301 whose diameter increases toward the slit 36. For this reason, the microwave irradiation area | region can be enlarged. In addition, the microwave irradiation region can be directed upward and radially outward.

<Fourth embodiment>
The difference between the microwave plasma processing apparatus of the present embodiment and the microwave plasma processing apparatus of the first embodiment is that the inner cylinder portion includes a reverse taper portion. Here, only differences will be described.

  FIG. 6 shows an enlarged cross-sectional view near the slit of the microwave plasma processing apparatus of the present embodiment. In addition, about the site | part corresponding to FIG. 3, it shows with the same code | symbol. As shown in FIG. 6, a tapered portion 311 that narrows from the bottom to the top is formed at the top of the outer cylinder portion 31. In addition, an inverted tapered portion 301 is formed at the upper portion of the inner cylinder portion 30 so as to expand from below to above.

  The slit 36 includes an upper end (one axial end) of the inner cylindrical portion 30 (specifically, the reverse tapered portion 301) and an upper end (one axial end) of the outer cylindrical portion 31 (specifically, the tapered portion 311). Arranged between. The slit 36 communicates with the second waveguide 33. The slit 36 has a ring shape extending in the circumferential direction. The radial width A1 of the slit 36 is smaller than the radial width A2 of the second waveguide 33. When viewed from the radially outer side or the radially inner side, the upper end of the inner cylinder part 30 and the upper end of the outer cylinder part 31 are substantially flush with each other. For this reason, the slit 36 faces upward. Above the slit 36, a ring-shaped plasma P is generated, as indicated by dotted line hatching in FIG.

  The microwave plasma processing apparatus according to the present embodiment and the microwave plasma processing apparatus according to the first embodiment have the same operational effects with respect to the parts having the same configuration. Moreover, according to the microwave plasma processing apparatus of the present embodiment, the microwave irradiation region can be directed upward.

<Others>
The embodiment of the microwave plasma processing apparatus of the present invention has been described above. However, the embodiment is not particularly limited to the above embodiment. Various modifications and improvements that can be made by those skilled in the art are also possible.

  The frequency of the microwave is not particularly limited. For example, what is necessary is just 300 MHz or more and 3 THz or less. For example, it may be 2.45 GHz or 915 MHz. When a microwave with a low frequency (for example, a 915 MHz microwave) is used, the ring diameter of the plasma P can be increased. For this reason, the area which the microwave plasma processing apparatus 1 can process at once becomes wide. For the microwave oscillation, a magnetron, klystron, traveling wave tube, gyrotron, Gunn diode, or the like may be used. The duty ratio of the microwave output is not particularly limited.

  Further, as the first waveguide 2, a coaxial cable-like flexible waveguide may be used. In this case, the processing may be performed by moving the second waveguide 3 in a scanning manner like a spray gun with respect to the fixed processing target surface 800.

  Moreover, you may arrange | position the inner cylinder part 30 and the outer cylinder part 31 so that relative displacement is possible. In this way, the deviation amount A3 can be freely adjusted. That is, the direction of the slit 36 (the generation position of the plasma P) can be adjusted freely.

  Moreover, the inner cylinder part 30 and the outer cylinder part 31 may be rectangular cylinders such as a triangular cylinder, a quadrangular cylinder, and a pentagonal cylinder other than a cylindrical shape. Moreover, the inner cylinder part 30 and the outer cylinder part 31 do not need to be arrange | positioned substantially coaxially.

  Further, it is preferable that the rectangular tube portion 20 and the plunger 21 are made of stainless steel or aluminum in order to maintain strength. In order to reduce the reflection of microwaves, the inner surface of the rectangular tube portion 20 may be plated with copper, silver, or the like having high conductivity. Similarly, in order to reduce the reflection of the microwave, the surface of the plunger 21 that is exposed to the microwave may be plated with copper, silver, or the like having high conductivity. The holding part 22, the inner cylinder part 30, and the outer cylinder part 31 are preferably made of copper or aluminum having high conductivity.

  In the above embodiment, helium gas is used as the plasma generating gas. However, the type of gas is not particularly limited. For example, one or more kinds of gases are appropriately selected from rare gases composed of argon, neon, krypton, and xenon, and molecular gases composed of hydrogen, nitrogen, oxygen, etc., and the selected gas is used for plasma generation. Gas may be used. Further, in order to stabilize the generated plasma, an organic solvent such as acetone may be vaporized and mixed in addition to the plasma generating gas.

  Further, the flow rate of the plasma generating gas is not particularly limited. Any flow rate may be used as long as the plasma P is stably generated. Moreover, the irradiation time of the plasma P with respect to the process target surface 800 of the process target object 80 is not specifically limited, either. For example, the irradiation time may be 1 second or more and 30 seconds or less.

1: microwave plasma processing apparatus, 2: first waveguide, 3: second waveguide.
20: Square cylinder part, 21: Plunger, 22: Holding part, 23: First waveguide path, 30: Inner cylinder part, 31: Outer cylinder part, 33: Second waveguide path (waveguide path), 34 : Spacer, 35: gas supply unit, 36: slit, 80: object to be processed, 90: microwave power source, 91: power monitor, 92: isolator, 93: power monitor, 94: matching unit, 95: pulse generator.
200: inner cylinder holding hole, 201: outer cylinder mounting hole, 301: reverse taper part, 310: gas supply part mounting hole, 311: taper part, 800: treatment target surface.
A1: radial width, A2: radial width, A3: deviation, P: plasma.

Claims (3)

An inner cylinder,
An outer cylinder disposed on the outer side in the axial direction of the inner cylinder; and
A waveguide path disposed between the inner cylinder part and the outer cylinder part, in which microwaves propagate in the axial direction;
A slit that is disposed between one axial end of the inner cylindrical portion and one axial end of the outer cylindrical portion, communicates with the waveguide, and has a narrower axial width than the waveguide.
A gas supply unit for supplying a plasma generating gas to the slit;
With
Under substantially atmospheric pressure conditions, the microwave and the plasma generating gas are passed through the slit to concentrate the microwave electric field to form a high electric field near the slit, and the high electric field generates the plasma. A microwave plasma processing apparatus that ionizes a working gas to generate plasma, and irradiates the plasma to perform a predetermined modification process on a processing target surface of a processing target. The processing target surface is movable relative to the slit,
The microwave plasma processing apparatus according to claim 1, wherein the slit extends in an endless annular shape in the circumferential direction.   3. The microwave plasma processing apparatus according to claim 1, wherein the inner cylinder part and the outer cylinder part are substantially similar to each other in outer shape in a cross section in the axial direction, and are arranged on substantially the same axis. .

Images