JP2007141634A - Atmospheric-pressure plasma generation head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an atmospheric-pressure plasma generation head capable of stably providing a highly-uniform processing region, in an atmospheric-pressure plasma head for generating a linear processing region. <P>SOLUTION: The shapes of both positive and negative electrodes 10 and 11A are each formed into a cylindrical or pipe-like form, and the positive and negative electrodes 10 and 11A are arranged in parallel with each other by perfectly fixing them. Then, the ratio of the diameter D1 of the positive electrode to the distance D2 between the surfaces of the positive and negative electrode is set between 1:0.5 and 1:3, and the negative electrodes 11A are arranged on the downstream side of the positive electrode 10 in a gas flow direction 14. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a plasma generation method used for plasma processing, and more particularly to an atmospheric pressure plasma generation head capable of obtaining a uniform line-shaped processing region in a pressure range of about atmospheric pressure or higher.

  Conventionally, plasma used for plasma processing is generated in a space in which a sealed chamber is evacuated and a processing gas is introduced into the chamber up to a required pressure.

  For this reason, in order to put a workpiece to be processed into and out of the processing chamber, a method is adopted in which the processing chamber is once opened to the atmosphere and evacuated after the workpiece is introduced. In addition, a chamber dedicated to loading and unloading is provided adjacent to the processing chamber, and with the processing chamber maintaining a vacuum, the load or unloading chamber is opened to the atmosphere and evacuated to remove workpieces in the atmosphere. A method of moving in and out of a vacuum processing chamber is also taken.

  These methods have a problem that the processing tact is lowered because they require evacuation and open time regardless of whether or not there is a load / unload chamber. Moreover, since the process of a workpiece | work becomes a batch type, it is unsuitable with respect to the workpiece | work which has a long shape like a film. In particular, when a load / unload chamber is provided, a mechanism for moving the workpiece in a vacuum is required, which complicates the apparatus and raises the apparatus cost.

  Another disadvantage is that the plasma generated in the processing chamber is slow in processing due to the low density of charged particles. This is because it is difficult to dissipate the electrodes and workpieces because the treatment is performed at a low pressure, and a large current cannot be supplied to the plasma generation. For this reason, techniques such as applying a rotational motion to charged particles using a magnetron to increase the charged particle density are also used, but the apparatus becomes complicated and the cost of the apparatus becomes a problem.

  As a technique for solving the above problems, a technique for generating plasma at or near atmospheric pressure has been proposed.

  The first method of atmospheric pressure plasma generation is called a torch type, which generates plasma inside a thin nozzle and introduces charged particles in the plasma to the surface of the object to be processed with a gas pressure. .

  As a second method of generating atmospheric pressure plasma, a method of generating high-density plasma in the atmosphere by mechanically rotating a cylindrical electrode at high speed (for example, see Patent Document 1) has been proposed. In addition, a method for performing this over a wide area (see, for example, Patent Document 2 and Patent Document 3) has been proposed. In these methods, it is possible to generate plasma under atmospheric pressure, and to generate high-density plasma with a high heat dissipation effect because the electrode rotates at high speed.

JP 9-31670 A JP 2001-348665 A JP 2002-261018 A

  In the torch type atmospheric pressure plasma generation method, the region to be processed has a spot shape due to the torch type shape. For large-scale processing objects, multiple torches are arranged in a row, but the density of charged particles differs between the torch directly below and the torch, making it difficult to obtain uniform processing. .

The rotating electrode method can obtain a line-shaped processing region. However, according to the description of Patent Document 3, the size of the rotating electrode requires a large electrode and a complicated mechanical element, as described as a diameter of 300 mm and a rotation speed of 5000 rotations / min ⁻¹ . As a result, it is difficult to stabilize the rotating shaft, and due to a change in the gap amount between the electrodes and a variation in the number of rotations, the charged particles become non-uniform and it is difficult to obtain a uniform treatment.

  Therefore, an object of the present invention is to provide an atmospheric pressure plasma generation head capable of stably obtaining a uniform processing region in an atmospheric pressure plasma head generating a line-shaped processing region.

  A feature of the present invention that achieves the above object is that, firstly, both the positive and negative electrodes have a cylindrical shape or a pipe shape, and the positive and negative electrodes are arranged in parallel. The positive cathode is completely fixed, including rotation about its axis.

  In the machining process, the cylinder and the pipe are easy to obtain surface accuracy compared to a flat surface or other curved surface, and an inexpensive and highly accurate electrode can be obtained. Further, by completely fixing the positive and negative electrodes, the gap between the electrodes can always be kept constant, and charged particles can be generated stably.

  Second, the ratio of the anode diameter to the distance between the positive and negative electrode surfaces is between 1: 0.5 and 1: 3. By setting it as the above, the electric potential gradient in the whole anode surface can be enlarged, and it becomes possible to produce | generate a charged particle efficiently.

  Third, the cathode is installed downstream of the anode in the gas flow direction. By setting it as the above, the charged particle produced | generated between the positive and negative electrodes can be carried on the flow of gas, and can be efficiently guide | induced to the process surface.

  According to the present invention, it is possible to obtain a line-shaped processing region with good uniformity.

  Hereinafter, the present invention will be described based on one embodiment shown in FIGS.

  FIG. 1 is a view showing the appearance of the processing head of the present invention. In FIG. 1, the processing head 1 has a configuration in which a discharge unit 1A and a nozzle head 1C are attached to an enlarged gas introduction tube 1B.

  Details of the discharge unit 1A are shown in FIG. FIG. 3 shows a partial cross-sectional view of the discharge unit. In FIG. 2, the anode 10 is attached inside the discharge unit base 12. As shown in FIG. 3, the anode 10 has a structure in which a glass lining 10B is applied to the surface of a metal core rod 10A.

  The anode 10 is coupled to a high-frequency power line (not shown) and a high-frequency application line of a matching box by an anode connector 10C.

  In the description here, the total length of the anode 10 is 500 mm, and the actual processing width is about 300 mm. However, the present invention does not limit the length of the anode 10 or the like.

  A cathode 11 is installed inside the discharge unit base 12 so as to be positioned downstream of the anode 10 with respect to the gas flow direction. The cathode 11 is installed so that the cathode main body 11A is divided into two and the anode 10 is sandwiched therebetween.

  The cathode main body 11A divided into two is electrically coupled by a cathode coupling plate 11C via a cathode mounting bolt 11B, and a high-frequency power supply device via a cathode connector 11D on the cathode coupling plate 11C. Combined with the ground line of the matching box.

  The discharge unit base 12 is made of a high dielectric material typified by PTFE or bakelite in order to insulate between the anode or the cathode. As with the discharge unit base 12, the anode end plate 13 is made of a high dielectric material.

  FIG. 4 is a view showing a cross section of the processing head of the present invention.

  In FIG. 4, reference numeral 14 denotes a process gas introduction direction, 15 denotes a discharge active region, and 16 denotes an active gas injection direction. Moreover, 2 has shown the process target processed with active gas.

  The features of the present invention will be described below with reference to FIG.

  The anode 10 is manufactured by manufacturing the mandrel 10A with a lathe process with high accuracy, applying a glass lining 10B, and polishing the surface of the glass lining 10B again with a lathe.

  The cathode 11A is obtained by processing a metal rod into a high-precision columnar shape with a lathe and performing planar processing except for the surface facing the anode 10 as shown in 11E shown in FIG.

  The anode 10 and the cathode 11A manufactured as described above are completely fixed in parallel with respect to the axis of the anode 10 and the cathode 11A through the discharge unit base 12 and the anode end plate 13. For this reason, the distance D2 between the surface of the anode 10 and the surface of the cathode 11A is unchanged.

  At this time, the diameter D1 of the anode 10 is desirably about 5 mm when the total length of the anode 10 is 500 mm or less. When the diameter of the anode 10 is extremely smaller than 5 mm, the anode 10 may be deformed by the dynamic pressure of the processing gas, and the uniformity of the distance D2 between the anode 10 and the cathode 11A may be impaired. On the contrary, when the diameter of the anode 10 is extremely larger than 5 mm, it is necessary to enlarge the cathode 11 accordingly, resulting in an unnecessarily large processing head, which may increase the apparatus cost.

  The ratio of the diameter D1 of the anode 10 to the distance D2 between the positive and negative electrode surfaces is preferably between 1: 0.5 and 1: 3. By making the diameter D1 of the anode 10 larger than the above ratio, the potential gradient on the anode surface is reduced, and the amount of generated charged particles is reduced. Conversely, by making the diameter D1 of the anode 10 smaller than the above ratio, it becomes easier to discharge only one of the two cathodes 11A, increasing the non-uniformity of the discharge and the amount of charged particles generated. Decrease.

  The two cathodes 11 </ b> A are desirably downstream of the anode 10 with respect to the processing gas introduction direction 14. At this time, the angle θ formed by the center of the anode 10 and the center of the arcs of the two cathodes (the center 11E of the dashed circle) is preferably 60 ° or more and less than 180 °. By doing in this way, the charged particles generated between the anode 10 and the cathode 11A are effectively moved in the active gas injection direction 16 without colliding with the anode 10 and the cathode 11A along the gas flow. It is guided.

  FIG. 5 is a diagram showing an application example of the processing head of the present invention.

  In FIG. 5, the processing object 2 passes through the plasma generation head 1 disposed above between the upstream conveyor 3 </ b> A that conveys the processing object 2 and the downstream conveyor 3 </ b> B that conveys the processing object 2. The surface of the substrate is plasma treated. In FIG. 5, the high-frequency power source, the matching box, the gas introduction device, the gas diffusion prevention cover, and the like are omitted in order to avoid complication of the drawing.

  A processing gas is introduced into the processing head 1 from the gas introduction direction 14, a high voltage is applied between the anode 10 and the cathode 11 </ b> A to generate charged particles, and the charged particles are placed on the flow of the processing gas as an active gas. The gas is injected from the gas injection direction 16.

  The processing object 2 is moved and passed by driving the upstream conveyor 3A and the downstream conveyor 3B below the region where the active gas is jetted from the plasma generation head 1. As a result, the active gas collides with the surface of the processing object 2 and the surface treatment of the processing object 2 is continuously performed.

  Regardless of the embodiment described above, it may be carried out as follows.

  You may perform this system in a vacuum or low pressure.

  Instead of the high frequency power source, a DC power source may be used.

It is a figure which shows the external appearance of this invention processing head. It is a figure which shows the discharge unit of this invention. It is a figure which shows this invention electrode layout. It is a figure which shows the cross section of this invention processing head. It is a figure which shows the example of application of this invention processing head.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Processing head, 1A ... Discharge unit, 1B ... Expansion gas introducing pipe, 1C ... Nozzle head, 2 ... Processing object, 3A ... Upstream conveyor, 3B ... Downstream conveyor, 10 ... Anode, 10A ... Core rod, 10B Glass lining, 10C ... Anode connector, 11 ... Cathode, 11A ... Cathode body, 11B ... Cathode mounting bolt, 11C ... Cathode coupling plate, 11D ... Cathode connector, 11E ... Cathode body first processed shape, 12 ... Discharge unit base, 13 ... anode end plate, 14 ... gas introduction direction, 15 ... discharge active region, 16 ... active gas injection direction.

Claims (3)

In an atmospheric pressure plasma generation head that includes at least one anode and a cathode, includes a power source that applies a voltage to the anode and the cathode, and ionizes a gas between the anode and the cathode to generate plasma.
The atmospheric pressure plasma generation characterized in that the anode and the cathode are formed in a cylindrical shape or a pipe shape with a conductor as a main material, and the longitudinal direction surfaces of the cathode facing the longitudinal direction surface of the anode are parallel to each other. head.   2. The atmospheric pressure plasma generation head according to claim 1, wherein the anode and the cathode are arranged so that the ratio of the diameter of the anode and the distance from the anode surface to the cathode surface is in the range of 1: 0.5 to 1: 3. An atmospheric pressure plasma generation head characterized by that. 2. The atmospheric pressure plasma generation head according to claim 1, wherein the cathode is installed downstream of the anode in the gas flow direction.

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