JP2017010792A - Plasma generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasma generator having a plasma torch having excellent durability.SOLUTION: A plasma generator 10 of the invention comprises: an electrode part 84 for receiving an excitation voltage; an exterior part 82 housing the electrode part 84 and having an internal space 80 through which a plasma gas passes; and an opening 88 disposed in the exterior part 82 and allowing the internal space 80 to communicate with the outside. Irregularities 98 are formed on a surface forming the internal space 80.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a plasma generator.

  Under pressure conditions near atmospheric pressure, the plasma is generated by filling the gap between one application electrode serving as the counter electrode and the other ground electrode with a plasma generating gas and applying a high frequency excitation voltage to the application electrode. A plasma generator that performs a cleaning process by discharging the plasma onto an object to be processed is known. In the plasma, ions, electrons, radicals, and ultraviolet rays exist, and these are subjected to an etching (shaving in micro units) action or an ashing (combustion, peeling) action on the object to be processed to remove dirt and the like. .

  Patent Document 1 discloses a plasma cutting apparatus that discharges plasma from a nozzle of a plasma torch in which a counter electrode that generates plasma is cylindrical, and cuts an object to be processed. Since the counter electrode and nozzle of the plasma torch are directly exposed to a high temperature plasma arc, it is necessary to suppress wear due to high heat. Therefore, the counter electrode and the nozzle are cooled by forming a water channel through which the cooling water flows around the counter electrode and the nozzle, and the counter electrode cooling water channel and the nozzle cooling water channel are separated from each other, thereby causing wear due to electric corrosion. It is suppressed and the durability of the plasma torch is improved.

JP 2008-119746 A

  However, the plasma cutting device (plasma generating device) described in Patent Document 1 is very effective in suppressing wear due to high temperature and electric corrosion of the plasma torch, but the cooling water channel for the counter electrode and the cooling for the nozzle. There is a problem in that the structure of the plasma torch is complicated in order to separate the water channel.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

  Application Example 1 A plasma generator according to this application example includes an electrode part that receives an excitation voltage, an exterior part that contains the electrode part and has an internal space through which a plasma gas passes, And an opening that is disposed in the exterior portion and communicates the internal space with the outside, and has a surface that forms the internal space and is uneven.

  According to this application example, since the surface forming the internal space through which the plasma gas passes is uneven, the contact area between the plasma gas inserted from the opening and the surface forming the internal space is small. The electrode portion and the exterior portion can be efficiently cooled by the plasma gas. Therefore, a plasma generator having a plasma torch with excellent durability can be obtained with a simple configuration in which irregularities are formed on the surface constituting the internal space of the plasma torch.

  Application Example 2 In the plasma generator according to the application example described above, it is preferable that the unevenness is disposed on a surface of the internal space on the electrode part side.

  According to this application example, by arranging the unevenness on the surface on the electrode part side, which becomes high temperature by generating plasma in the internal space, cooling by the plasma gas is made more efficient, and wear due to high heat of the plasma torch is reduced. It can be suppressed more.

  Application Example 3 In the plasma generator according to the application example described above, it is preferable that the unevenness is arranged in a periodic manner.

  According to this application example, since the periodic unevenness can be easily processed by repeatedly performing grooving with a lathe device or the like, a plasma generator having a plasma torch having a simple structure and excellent durability is provided. Can be obtained.

  Application Example 4 In the plasma generator according to the application example described above, it is preferable that the unevenness is spiral.

  According to this application example, since the spiral irregularities can be easily machined by threading with a lathe device or the like, a plasma generator having a plasma torch with excellent durability with a simple configuration is obtained. Can do.

  Application Example 5 In the plasma generator according to the application example, it is preferable that the unevenness surrounds the electrode portion.

  According to this application example, since the unevenness is formed so as to surround the electrode part, the contact area with the plasma gas is increased, and the electrode part that becomes high temperature is cooled more efficiently by generating plasma. can do.

  Application Example 6 In the plasma generation apparatus according to the application example described above, it is preferable that the unevenness is a spiral arranged on the outer surface of the electrode portion.

  According to this application example, by forming a spiral (female screw) on the outer surface of the electrode unit, the spiral becomes an internal space having irregularities, and the electrode unit is cooled by allowing the plasma gas to pass through the spiral. be able to.

  Application Example 7 In the plasma generator according to the application example described above, it is preferable that the unevenness is formed by taps.

  According to this application example, since the tap can easily form a spiral, an internal space having spiral irregularities inside the spiral can be easily processed.

  Application Example 8 In the plasma generator according to the application example described above, the exterior portion includes discharge holes for plasma discharge, and the discharge holes are arranged in a direction in which the electrode portions and the discharge holes are aligned. It is preferable that it is arranged close to the side.

  According to this application example, since the opening for supplying the plasma gas is disposed near the discharge hole, the plasma gas supplied from the opening is an internal space formed by a surface having irregularities. And reach the electrode part where plasma is generated. Therefore, the contact area between the plasma gas and the uneven surface can be made long and large. Therefore, it is possible to cool the electrode portion more efficiently through the unevenness.

  Application Example 9 In the plasma generating apparatus according to the application example described above, it is preferable that the electrode portion includes a cylindrical external electrode and an internal electrode disposed inside the external electrode. .

  According to this application example, since the internal electrode is arranged inside the cylindrical external electrode, by applying an excitation voltage to either the external electrode or the internal electrode, Plasma can be generated between them.

  Application Example 10 In the plasma generation apparatus according to the application example described above, it is preferable that a gap between the external electrode and the internal electrode communicates with the internal space.

  According to this application example, since the gap between the external electrode and the internal electrode communicates with the internal space, the plasma gas that has passed through the internal space can be put into the gap between the external electrode and the internal electrode. Therefore, plasma can be generated by filling the gap between the external electrode and the internal electrode with a plasma gas and applying an excitation voltage.

  Application Example 11 In the plasma generator according to the application example described above, it is preferable that at least one of the external electrode and the internal electrode has a dielectric layer disposed on the surface on the air gap side.

  According to this application example, since the dielectric layer is disposed on the air gap side surface of at least one of the external electrode and the internal electrode, the arc discharge is prevented and the uniform glow discharge It is possible to generate plasma stably.

  Application Example 12 In the plasma generator according to the application example described above, it is preferable that at least one of the external electrode and the internal electrode includes aluminum as a material, and the dielectric layer is anodized.

  According to this application example, since at least one of the external electrode and the internal electrode is made of a material containing aluminum, the thermal conductivity is large, so that the cooling efficiency can be improved, and the anodized dielectric is obtained by oxidizing the surface. A body layer can be formed easily. In addition, even if the surface is damaged and a part of the dielectric layer of the alumite is lost, the alumite can be formed by generating natural plasma with air in the atmosphere or using a gas containing oxygen atoms. Therefore, durability can be improved.

Schematic which shows the structure of the plasma generator which concerns on 1st Embodiment of this invention. 1 is a schematic longitudinal sectional view showing a configuration of a plasma torch according to a first embodiment of the present invention. The schematic cross-sectional view of the AA line in FIG. The schematic longitudinal cross-sectional view which shows the structure of the plasma torch concerning 2nd Embodiment of this invention. The schematic cross-sectional view of the BB line in FIG. The schematic cross-sectional view of the CC line in FIG. The schematic cross-sectional view of the DD line in FIG. The schematic longitudinal cross-sectional view which shows the structure of the plasma torch concerning 3rd Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each figure shown below, the size and ratio of each component may be described differently from the actual component in order to make each component large enough to be recognized on the drawing. is there.

<First Embodiment>
First, as an example of the plasma generating apparatus according to the first embodiment of the present invention, a plasma generating apparatus having a cylindrical plasma torch is cited, and its schematic configuration will be described with reference to FIGS.
FIG. 1 is a schematic diagram showing the configuration of the plasma generator according to the first embodiment of the present invention. FIG. 2 is a schematic longitudinal sectional view showing the configuration of the plasma torch according to the first embodiment of the present invention. FIG. 3 is a schematic cross-sectional view taken along line AA in FIG.

  As shown in FIG. 1, the plasma generator 10 of this embodiment includes a plasma torch 20 that generates plasma, an RF power source 30 that supplies an excitation voltage, and a matching unit that matches impedances of the plasma torch 20 and the RF power source 30. 40, a gas cylinder 50 for supplying the plasma gas, a mass flow controller (MFC) 60 for adjusting the supply amount of the plasma gas, a valve 70 for controlling the plasma gas supplied to the plasma torch 20, and the like.

  As shown in FIG. 2, the plasma torch 20 has a cylindrical shape, accommodates an electrode portion 84, an exterior portion 82 having an internal space 80 through which plasma gas passes, and an electrode that receives an excitation voltage. Part 84.

  The exterior portion 82 has a cylindrical shape with both ends in the long side direction closed, and a discharge hole 86 that is a nozzle for plasma discharge penetrating along the long side direction is provided at one end portion. Further, the gas for plasma that is arranged near the discharge hole 86 in the direction in which the electrode portion 84 and the discharge hole 86 are arranged, penetrates along the direction intersecting the long side direction, and communicates the internal space 80 with the outside. An opening 88 serving as a supply port is provided. As a material of the exterior part 82, aluminum excellent in heat dissipation is preferable.

  The electrode portion 84 is cylindrical and includes an external electrode 90 serving as a ground electrode and an internal electrode 92 serving as an application electrode, and is accommodated in the internal space 80 of the exterior portion 82. An internal electrode 92 is disposed inside the cylindrical external electrode 90, and a gap 94 is provided so that the external electrode 90 and the internal electrode 92 do not contact each other. A gap 94 formed by the external electrode 90 and the internal electrode 92 communicates with the internal space 80 at the other end of the exterior portion 82. Moreover, the exterior part 82, the external electrode 90, and the internal electrode 92 are arrange | positioned concentrically as shown in FIG. In addition, as a material of the external electrode 90 and the internal electrode 92, aluminum, titanium, or SUS (stainless steel) is used.

  The external electrode 90 is joined to the internal space 80 side of one end of the exterior portion 82, and a dielectric layer 96 such as quartz glass or ceramic is disposed on the surface of the external electrode 90 on the air gap 94 side, and the opposite side Concavities and convexities 98 are arranged on the surface constituting the internal space 80.

  The dielectric layer 96 is disposed in order to prevent arc discharge and obtain a uniform glow discharge when generating plasma. In the present embodiment, the dielectric layer 96 is disposed on the external electrode 90, but the present invention is not limited to this, as long as it is disposed on the surface of at least one of the external electrode 90 and the internal electrode 92 on the gap 94 side. Good.

  The irregularities 98 are periodically arranged along the cylindrical longitudinal direction on the surface of the external electrode 90 constituting the electrode portion 84 on the side constituting the internal space 80, and are formed surrounding the electrode portion 84. Yes. This is to increase the contact area with the plasma gas passing through the internal space 80 and to increase the cooling efficiency. As a material of the unevenness 98, a metal material having a high thermal conductivity is preferable. Further, the periodic unevenness 98 can be easily processed by grooving with a lathe device or the like. The unevenness 98 may be integrated with the external electrode 90. By integrating, it is not necessary to use a bonding material for bonding the unevenness 98 and the external electrode 90, so that the cooling efficiency in the internal space 80 can be further increased.

  In the present embodiment, the irregularities 98 are arranged in a periodic shape, but the present invention is not limited to this, and the irregularities 98 may be arranged in a spiral shape. This is because an effect similar to that of a periodic shape can be obtained even in a spiral shape. The spiral unevenness 98 can be easily machined by threading with a lathe device or the like.

  The internal electrode 92 is joined to the other end opposite to the end of the exterior part 82 to which the external electrode 90 is joined via an insulating part 100 such as quartz glass or ceramic.

  Note that when at least one of the external electrode 90 and the internal electrode 92 is made of a material containing aluminum, aluminum has high thermal conductivity, and thus cooling efficiency can be improved. Further, the alumite dielectric layer 96 can be easily formed by oxidizing the surface. Furthermore, even if the surface is damaged and a part of the alumite that is the dielectric layer 96 disappears, alumite is formed by generating natural plasma by air in the atmosphere or using a gas containing oxygen atoms. Therefore, durability can be improved.

Next, the plasma generation mechanism in the plasma torch 20 will be described with reference to FIG. 2 again. In FIG. 2, arrows indicate plasma gas and plasma flow.
When a plasma gas such as helium (He) or argon (Ar) is introduced into the opening 88 provided in the exterior portion 82, the plasma gas has an internal space 80 constituted by the exterior portion 82 and the electrode portion 84. Flows from the opening 88 side toward the side where the internal electrode 92 is joined to the exterior portion 82. Therefore, the external electrode 90 heated by generating plasma is cooled by the introduced low-temperature plasma gas through the unevenness 98 provided in contact with the external electrode 90.

  Thereafter, the plasma gas passes through the internal space 80 on the side where the internal electrode 92 is joined to the exterior portion 82 and flows into the gap 94 formed by the external electrode 90 and the internal electrode 92, and the gap 94 is the plasma gas. It is filled. At that time, when an excitation voltage is applied from the RF power source 30 (see FIG. 1) to the internal electrode 92 that is an application electrode, the external electrode 90 that is a ground electrode grounded to the ground via the exterior portion 82. A uniform glow-like discharge is generated, the plasma gas is excited, and plasma is generated in the gap 94. In the present embodiment, the external electrode 90 is described as a ground electrode and the internal electrode 92 is described as an application electrode. However, the present invention is not limited to this, and the external electrode 90 is attached to the exterior portion 82 via an insulating material. The internal electrode 92 and the exterior portion 82 may be electrically joined as a ground electrode by joining and applying. Even in this case, the same effect as the present embodiment can be obtained.

  The generated plasma is pushed out from the gap 94 in the direction of the discharge hole 86 by the plasma gas introduced from the opening 88 and is discharged from the discharge hole 86 to the outside of the exterior portion 82. By irradiating the object to be processed with the discharged plasma, dirt such as an organic substance adhering to the surface of the object to be processed can be ashed and washed.

  Note that the plasma gas sent into the gap 94 to discharge plasma becomes plasma by the excitation voltage and is discharged from the discharge hole 86. By repeating this operation, it is possible to stably discharge the plasma and clean the object to be processed.

  As described above, the plasma generating apparatus 10 according to the present embodiment has a surface on the electrode portion 84 side that constitutes the internal space 80 in the internal space 80 constituted by the exterior portion 82 and the electrode portion 84, that is, the surface. Concavities and convexities 98 that can increase the contact area with the plasma gas are provided on the surface of the external electrode 90 on the internal space 80 side. Therefore, when the plasma gas passes through the internal space 80 and reaches the gap 94 between the external electrode 90 and the internal electrode 92 that generate plasma, the external electrode 90 heated by the plasma generated in the gap 94 is cooled to a low temperature. The plasma gas can be efficiently cooled. Therefore, the plasma generator 10 having the plasma torch 20 having excellent durability can be obtained.

  The irregularities 98 are arranged in a periodic manner, and the periodic processing can be easily performed by repeatedly performing grooving with a lathe device or the like. Therefore, it is possible to easily manufacture the unevenness 98 that enhances the cooling efficiency by the plasma gas, and to obtain the plasma generator 10 having the plasma torch 20 having excellent durability.

  Further, since the unevenness 98 is disposed so as to surround the external electrode 90 of the electrode portion 84, the contact area with the plasma gas can be increased, and the electrode portion 84 that becomes high temperature by generating plasma can be further increased. It can be cooled efficiently.

  In addition, a discharge hole 86 for plasma discharge is provided at one end of the exterior portion 82, and an opening 88 for supplying plasma gas is disposed near the discharge hole 86. Therefore, the plasma gas supplied from the opening 88 passes through the internal space 80 formed by the surface having the unevenness 98, and reaches the gap 94 of the electrode portion 84 where the plasma is generated. Since the contact area between the plasma gas and the unevenness 98 can be increased, the cooling efficiency can be further increased.

  Further, in the electrode portion 84, the internal electrode 92 is disposed inside the cylindrical external electrode 90, and the gap 94 between the external electrode 90 and the internal electrode 92 and the internal space 80 communicate with each other. Plasma can be generated in the gap 94 by filling the gap 94 with the plasma gas that has passed through and applying an excitation voltage to the internal electrode 92.

  In addition, since the dielectric layer 96 is disposed on the surface of the external electrode 90 on the gap 94 side, arc discharge can be prevented and uniform glow-like discharge can be achieved, and plasma can be generated stably. .

Second Embodiment
Next, a plasma torch 20a of a plasma generator according to a second embodiment of the present invention will be described with reference to FIGS.
FIG. 4 is a schematic longitudinal sectional view showing the configuration of the plasma torch according to the second embodiment of the present invention. FIG. 5 is a schematic cross-sectional view taken along line BB in FIG. 6 is a schematic cross-sectional view taken along line CC in FIG. FIG. 7 is a schematic cross-sectional view taken along line DD in FIG.
Hereinafter, the plasma torch 20a according to the second embodiment will be described focusing on differences from the plasma torch 20 of the first embodiment described above. Moreover, the same code | symbol is attached | subjected to the same structure and the description is abbreviate | omitted about the same matter.

As shown in FIG. 4, the plasma torch 20a according to the second embodiment is different in the shape of the exterior portion 82a.
The exterior portion 82a has a cylindrical shape, and has an internal structure on the side where the internal electrode 92 is joined via the insulating portion 100 along the longitudinal direction, the central portion, and the side where the discharge hole 86 is provided. Is different.

  On the side where the internal electrode 92 is joined via the insulating portion 100 of the exterior portion 82a, as shown in FIG. 5, the internal space 80a1 is configured by an inner surface of the exterior portion 82a and an outer surface of the internal electrode 92. . By this internal space 80a1, the plasma gas introduced from the opening 88 and passing through the central internal space 80a2 can be sent into the gap 94 formed by the external electrode 90 and the internal electrode 92.

  As shown in FIG. 6, the central portion of the exterior portion 82 a has an inner space 80 a 2 and an outer surface that is an outer periphery of the electrode portion 84 having the external electrode 90 and the internal electrode 92, that is, the exterior portion 82 a surrounding the electrode portion 84. A plurality of spirals (female screws) are arranged. The plurality of spirals communicate with the internal space 80a1 on the side where the internal electrode 92 is joined via the insulating portion 100 and the internal space 80a3 on the side where the discharge hole 86 is provided. Therefore, the plasma gas introduced from the opening 88 can be sent into the gap 94 through the internal spaces 80a3, 80a2, and 80a1.

  In the spiral provided on the outer side of the electrode portion 84, the thread formed on the inner peripheral portion becomes the unevenness 98a and constitutes the internal space 80a2. Therefore, the electrode portion 84 can be cooled by allowing the plasma gas to pass through the internal space 80a2 having the unevenness 98a that becomes the inside of the spiral. Further, since the spiral unevenness 98a can be processed by a tap for female thread processing, a spiral that becomes the internal space 80a2 having the unevenness 98a can be easily formed.

  As shown in FIG. 7, the side where the discharge hole 86 of the exterior portion 82 a is provided is configured such that the internal space 80 a 3 is composed of an inner surface of the exterior portion 82 a and an outer surface of the exterior portion 82 a surrounding the external electrode 90. Yes. By this internal space 80a3, the plasma gas introduced from the opening 88 can be supplied to the internal space 80a2 formed by a plurality of spirals penetrating the central portion of the exterior portion 82a along the longitudinal direction. Therefore, the outer peripheral part of the electrode part 84 can be cooled with the plasma gas.

  With such a configuration, when the plasma gas passes through the internal space 80a2 formed by the spiral, the screw thread of the spiral becomes the unevenness 98a, and the contact area with the plasma gas becomes large. 84 can be cooled. Therefore, a plasma generator having a plasma torch 20a having excellent durability can be obtained.

<Third Embodiment>
Next, a plasma torch 20b of a plasma generator according to a third embodiment of the present invention will be described with reference to FIG.
FIG. 8 is a schematic longitudinal sectional view showing the configuration of the plasma torch according to the third embodiment of the present invention.
Hereinafter, the plasma torch 20b according to the third embodiment will be described focusing on differences from the plasma torch 20 of the first embodiment described above. Moreover, the same code | symbol is attached | subjected to the same structure and the description is abbreviate | omitted about the same matter.

In the plasma torch 20b according to the third embodiment, the exterior portion 82b and the electrode portion 84b have different shapes, and the external electrode 90b is installed outside the exterior portion 82b.
The exterior portion 82b has a substantially cylindrical shape having an internal space 80b, and an internal electrode 92b serving as an application electrode is disposed in the internal space 80b. At one end of the exterior portion 82b, the internal electrode 92b is joined via the insulating portion 100, and a first opening 86b penetrating along the direction intersecting with the extending direction of the internal electrode 92b is provided. ing. The other end is provided with a second opening 88b penetrating along the direction in which the internal electrode 92b extends.

The electrode portion 84b includes an external electrode 90b serving as a ground electrode, an internal electrode 92b serving as an application electrode, and the like.
The internal electrode 92b is provided with periodic irregularities 98b on the surface on the internal space 80b side, and is uniform on the tip side on the side where the second opening 88b is provided, on the side of the gap 94b with the external electrode 90b. A dielectric layer 96b necessary for achieving a glow-like discharge is disposed.

  When the plasma gas introduced from the first opening 86b passes through the internal space 80b of the exterior portion 82b, the plasma gas comes into contact with the unevenness 98b provided in the internal electrode 92b to cool the internal electrode 92b. When an excitation voltage is applied to the internal electrode 92b after being sent to the gap 94b with the external electrode 90b, plasma is generated in the gap 94b. Therefore, by arranging the workpiece 102 such as a silicon wafer on the external electrode 90b, the surface of the workpiece 102 can be cleaned by irradiating the surface of the workpiece 102 with the generated plasma. .

  With such a configuration, the unevenness 98b provided on the internal electrode 92b heated by the generated plasma increases the contact area with the plasma gas and increases the cooling efficiency. Therefore, a plasma generator having a plasma torch 20b having excellent durability can be obtained.

  DESCRIPTION OF SYMBOLS 10 ... Plasma generator, 20 ... Plasma torch, 30 ... RF power supply, 40 ... Matching device, 50 ... Gas cylinder, 60 ... Mass flow controller, 70 ... Valve, 80 ... Internal space, 82 ... Exterior part, 84 ... Electrode part, 86 DESCRIPTION OF SYMBOLS ... Discharge hole, 88 ... Opening part, 90 ... External electrode, 92 ... Internal electrode, 94 ... Air gap, 96 ... Dielectric layer, 98 ... Concavity and convexity, 100 ... Insulation part, 102 ... To-be-processed object.

Claims (12)

An electrode receiving an excitation voltage;
An exterior part containing the electrode part and having an internal space through which the plasma gas passes;
An opening that is disposed in the exterior and communicates the internal space with the outside,
A plasma generating apparatus characterized in that the surface constituting the internal space has irregularities.   The plasma generator according to claim 1, wherein the unevenness is disposed on a surface of the internal space on the electrode part side.   The plasma generator according to claim 1, wherein the irregularities are arranged in a periodic manner.   The plasma generator according to any one of claims 1 to 3, wherein the irregularities are spiral.   The plasma generator according to any one of claims 1 to 4, wherein the unevenness surrounds the electrode portion.   The plasma generator according to any one of claims 1 to 4, wherein the unevenness is a spiral arranged on an outer surface of the electrode portion.   The plasma generating apparatus according to claim 6, wherein the unevenness is formed by a tap.   The said exterior part has a discharge hole for plasma discharge, and the opening is arranged near the discharge hole in the direction in which the electrode part and the discharge hole are arranged. The plasma generator according to any one of claims 1 to 7.   The said electrode part has a cylindrical external electrode and the internal electrode arrange | positioned inside the said external electrode, It is any one of Claim 1-8 characterized by the above-mentioned. The plasma generator described.   The plasma generating apparatus according to claim 9, wherein a gap between the external electrode and the internal electrode communicates with the internal space.   The plasma generating apparatus according to claim 9 or 10, wherein at least one of the external electrode and the internal electrode has a dielectric layer disposed on a surface on the gap side.   12. The plasma generating apparatus according to claim 11, wherein at least one of the external electrode and the internal electrode includes aluminum as a material, and the dielectric layer is anodized.

Images