JPS63120163A - Low temperature plasma generator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a low-temperature plasma generator used in low-temperature plasma treatment used for surface treatment of organic materials, inorganic materials, etc.

BACKGROUND OF THE INVENTION In recent years, plasma generated by high-frequency discharge has been used for surface treatment and thin film formation of semiconductors, metals, organic materials, inorganic materials, and the like. As one of the effects of plasma treatment, it is known that, for example, by treating cloth or the like in a low-temperature plasma atmosphere, desizing, scouring, or finishing effects can be obtained. An internal electrode type low-temperature plasma processing apparatus for this treatment is, for example, Journal of the Textile Machinery Society: Vol. 38, No. 4, 198-19.
9 (1985), Japanese Patent Publication No. 60-31937, Japanese Patent Publication No. 60-11149, Japanese Patent Publication No. 60-11150, etc. Its basic structure is shown in FIG. In other words, in FIG. 5, in a processing chamber (1) capable of maintaining a vacuum, there is a high voltage application electrode plate (2) and a ground electrode plate (3) facing it parallel to it at a certain distance. and apply the high voltage! Pole plate (2)
A feeding point (2a) is provided approximately in the center of the ground electrode plate (3).
A grounding point (3a) is provided approximately in the center of both chambers 1 (2),
During (3), a high frequency high voltage is applied from the high frequency power supply device (4). Feed the sealed material (6) to be treated from the vacuum-sealed inlet (5a) by the supply loaf (7a),
The process is carried out between the two chambers W1 (2) and (3), and the exit (5
From b), the film is wound up by a winding roller (7b).

In addition, a predetermined amount of a predetermined processing gas such as air or oxygen is continuously fed into the processing chamber (1) from the air supply port (8a).
A predetermined pressure is maintained while continuously exhausting air from the exhaust port (8b). In these devices, a plasma generation electrode consisting of a high voltage application electrode plate (2) and a grounded electrode plate (3) is installed in a vacuum processing chamber (1), so that it penetrates the wall and draws vacuum from the atmosphere. An electric line (hereinafter referred to as a power supply section) (9) for supplying high-frequency power to the inside is required.

Problems to be Solved by the Invention As mentioned above, in the conventional apparatus illustrated in FIG. The power supply section (9
) and the high voltage applied Xa plate (2) and the surrounding reaction chamber (
1) It is inevitable that plasma will be generated between the main body and metals in the reaction chamber (1). This results in significant power losses. This power loss can overheat the main body of the reaction chamber (1) and nearby insulators, or overheat the power supply section (9), electrode plates (2), and (3) themselves.
cause thermal distortion and thermal deterioration over a wide range of
Furthermore, the plasma shifts to mark discharge, causing damage to the plasma processing equipment and high frequency power supply, making it impossible to continue plasma processing for a long time. In other words, it generates plasma in the target space, and that's a plus! There were problems such as the difficulty of injecting high-frequency power into the system at a high density. Also, vt
, the plasma generated between the poles is also generated between the power supply side and the opposite side (Ii
lil had different intensities and the treatment effects were non-uniform.

Particularly in the case of fabric and film treatment, a large area or large volume of plasma is required, which requires large equipment on an industrial scale, but generating uniform, large-scale plasma using high-frequency discharge requires a high frequency. This becomes difficult as the wavelength becomes shorter or as the device becomes larger.

The present invention provides a power supply section of a low temperature plasma processing apparatus and! The present invention aims to provide a low-temperature plasma generation device that solves the above-mentioned problems and achieves uniform and efficient processing effects.

Friendly Means for Solving the Problems A friend for solving the above problems The low temperature plasma generator of the present invention is a low temperature plasma generator that generates low temperature plasma by back frequency discharge under low pressure. Ground the opposing high voltage application electrode! A plasma generating electrode consisting of a pole is formed by surrounding the high voltage applying electrode with a ground electrode having a larger side surface than the high voltage applying electrode,
A power supply line that is externally grounded to supply high-frequency power to the plasma generation electrode? The inner conductor of the feed line 11L is connected to the high voltage application a pole and the outer conductor t to the ground electrode at the shortest distance, respectively, and the feed line is connected so that its characteristic impedance is three times the plasma impedance of the plasma generation electrode. One or more wires are connected in parallel 1c to obtain a very low value.
It is characterized by having a length such that the ratio of reactance to resistance in the sending end impedance is 1 or less when connected.

Effect In the above configuration, since the high voltage application electrode of the plasma generation electrodes is arranged so as to be surrounded by the ground electrode with a large area, the radio waves generated between the two electrodes may leak to the external space other than between the two electrodes. This prevents electrostatic coupling with surrounding metals and discharge, and no plasma is generated anywhere other than between the electrodes. In other words, since the electrode structure has no mutual interference, is it a plasma generating electrode with a similar structure? It is also possible to arrange several pieces in the same reaction chamber to create a plasma generator with a larger area and larger volume as a whole. In addition, by using a feeder line such as a coaxial cable whose external part is grounded and shielded, and by connecting this feeder line to both electrodes at the shortest possible distance, and by adjusting the number of feeder lines connected in parallel, the synthesized characteristic impedance is Set the value to be three times lower than the impedance, and set the reactance/reactance at the sending end impedance.
By setting the length so that the resistance ratio is less than 1, the plasma impedance and the feed line impedance are close, so reflection at the connection point between the wire and the electrode is small, and therefore the standing wave generated on the feed line is reduced. It is smaller and eliminates local overheating of the power supply line. In addition, by setting the length of the feeder line such that the reactance/resistance ratio in the throat sending end impedance is 1 or less, electrical matching between the high frequency power supply and the plasma generation electrode including the feeder line is achieved. It becomes easier to use high frequency power! The supply efficiency to the poles is improved. Furthermore, by using a power supply line such as a coaxial cable whose outside is grounded and shielded, unnecessary plasma is not generated due to electrostatic coupling between the power supply line and the reaction chamber body or metals in the reaction chamber. In this way, high frequency power can be efficiently supplied from the high frequency power supply device to the plasma generation electrode, and highly uniform plasma can be generated.

Embodiment An embodiment of the present invention will be described based on the drawings. First, the plasma generating IE electrode will be explained with reference to FIGS. 1 to 3. Is Figure 1 an example of a plasma generation electrode? The figure is a front view, and (B) is a side view. A high voltage application electrode plate συ is installed upright, and ground electrode plates (12
a) and (12b) are erected parallel to each other and facing each other, and the ground electrode plates (12a) and (12b) have a larger area than the high voltage application electrode (2), and the ground electrode plate (12a)
, (12b), a plasma generation W and four poles are arranged so as to surround the high voltage application electrode plate Ql). The supply line α4 is connected to the upper and side ends of the plasma generation electrode port.
An unbalanced coaxial Google is connected as a. That is, the outer conductor of the feeder line α4 consisting of the unbalanced coaxial coupe μp≧, that is, the shield side conductor (14a), (14b
) are each equipped with two grounding W, electrode plates 12a), (12
b) The internal conductor (14c) is connected to the high voltage application electrode plate (6) with the shortest possible distance.

Figure 2 shows another example of plasma generation poles, with the figure being a front view and the figure B being a side view.
5a) and (15b) are erected facing each other in parallel with a certain interval, and the high voltage application electrode plates (15a) and (15
b) Larger area ground electrode plate (16a), (16
b) is the high voltage application electrode plate (15a), (15b)
The plasma generation poles αη are arranged in parallel and facing each other at regular intervals so as to surround the plasma. A balanced cable is connected as a # electric wire (to) to the upper part of the plasma generator [17] -1li11@. In other words, the external conductor of the power supply consisting of a balanced type coupe, that is, the four seed μ seeds 1iIli (18a) and (18b), are connected to the two grounding plates. ! The inner conductors (18C) and (18d) are connected to the two high voltage applied FM electrode plates 16a and 16b.
(15a) and (15b) K are both connected by the shortest distance.

As illustrated in FIGS. 1 and 2 above, on the plasma generation electrode side and αη, the high voltage application electrode plate 0 and (15a) and (15b) are two large-area grounded electrode plates (12a). , (12b) and (16a),
(16b) so that the generated radio waves leak into the external space other than between the two electrodes,
Eliminates electrostatic coupling with surrounding metals and discharge.

The difference in size between the high voltage application electrode and the grounded X pole, which is necessary to suppress the plasma leakage that occurs between the electrodes within a practically acceptable range, is determined by the pressure inside the plasma reaction chamber and the input high frequency power. related to. In other words, as the pressure decreases, the mean free path of the seed electrons becomes longer, and as they diffuse, vct
It begins to leak to the outside. On the other hand, when the pressure increases, the plasma tends to concentrate on a certain part of the electrode, and the VC finally shifts to arc discharge. Even when the high frequency input applied to the IT electrode is increased, the plasma becomes stronger and gradually overflows outside the electrode. For this reason, the normally used low-temperature plasma processing conditions, that is, frequency 1156 MHz, vacuum degree 0.1
~2. In the case of OTorr, input 0.01 to IW/ctd, and the plasma generating electrode (2) shown in Fig. 1, as shown in Fig.
).

It is desirable that the difference 2x between the lengths of each side of (12b) be at least twice, preferably at least four times, the distance t between both electrode plates. Further, when a plurality of power supply lines are connected in parallel and used, the connection points to the plasma generation electrodes do not need to be connected at one point, and the power supply points can be distributed to make the plasma uniform. In this case - generally the connection point of each its to the plasma generating electrode is ! The position where the average distance to each point on the top is the shortest is desirable. Note that if the above conditions are satisfied, both the high voltage application electrode and the ground electrode do not need to be plate-shaped, but may be block-shaped, mesh-shaped, grid-shaped, etc. It may also have a rod-like structure. Furthermore, as illustrated in the perspective view of Fig. 3, the high voltage applying electrodes are divided into a plurality of parts (19a) and (L9b) and arranged in parallel, and the ground electrodes are arranged in parallel surrounding f'L. Both ends of the two sheets are closed and arranged in a ring to form a plasma generating electrode 1a1), and the high voltage applying electrode (19a)
, (19b) may be connected to the power supply lines (A) 2g and 3 respectively.

Note that the shield side conductors (14a), (14b), (
18a), (18b) (22a), (22b), (
For 23a) and (23b), copper braid or copper tape is generally used.

Next, a low-temperature plasma processing apparatus for fabric incorporating a low-temperature plasma generating apparatus using the plasma generating electrode shown in FIG. 1 will be described with reference to FIG. 4 (B). Fourth
In [F]), vacuum? As shown in Fig. 1, in the processing chamber (c) which can hold the high voltage application electrode plate (6), large-area electrodes (6) are placed at regular intervals on both sides of the high-voltage application electrode plate (6), which is vertically installed. 2x>2t) Ground! Pole plate (12a)
, (12b) Plasma generating electrodes are arranged facing each other in parallel, and the high frequency power sent from the high frequency power supply device is sent from the matching box (e) to the feeder line α1g whose outside is grounded and shielded. Power is supplied to the plasma generating electrode port through the plasma generating electrode port. Two feeder lines 0.1) are connected in parallel.

Further, inside the processing chamber, the sheet-like material to be processed is fed through a vacuum-sealed inlet (28a) by a supply roller (29a), and then fed into the processing chamber by a guide roller (30a).

(30b), (30c), (30d), (30e
), (3Of), (30g) to both electrodes CLI)
.

In addition, the processing chamber (c) is exhausted from the exhaust port (31a),
Processing gases such as air, oxygen, and nitrogen are continuously supplied from the air supply port (31b) while maintaining a predetermined pressure.

Using the above-mentioned low-temperature plasma treatment apparatus, a processed polyester fabric was subjected to low-temperature plasma treatment under the following conditions.

(Conditions) Fabric to be treated: Polyester processed yarn fabric (Warp I50, 110 threads; Weft 150D x 255 threads/inch) Processing gas: Oxygen treatment gas flow rate: 4 J/min Vacuum degree - 0.5 Torr Processing speed...100σ/min High frequency power supply frequency...13.56MHz...
2KW Electrode dimensions...Length 900mm, Length 1800ttvx
Electrical overture interval...60 questions f6 electric wire...2 Feeding line length...1.5m Combined impedance of feeding ring...25Ω Plasma impedance...3oΩ, feeding line reactance/resistance... -0.15 As a comparative example, the same fabric as in the above example was treated under the same plasma generation conditions using the apparatus shown in FIG.

The water absorbency of the treated fabrics obtained in the above Examples and Comparative Examples was
SL-1096 (bisic method) vcxv, measured in the width direction of the fabric. The results are shown in Figure 6.
When used with the apparatus of the example shown in FIG. 4, uniform and excellent water absorption performance was imparted to the fabric in the width direction. kofLI
In contrast, when the conventional processing device shown in FIG. 5 was used, the water absorption performance was uneven in the width direction of the fabric, and was unfavorable as it was poor at both ends (edges). As is clear from these results, the low-temperature plasma processing apparatus of the above embodiment has extremely high efficiency and uniformity in plasma generation, and can perform uniform plasma processing.

In addition, in the low-temperature plasma treatment apparatus as shown in FIG. Reduce the reflection at the connection point between the wire σ, the high voltage application electrode plate Ql) and the grounded electrode plates (12a) and (12b), and improve the efficiency of supplying high-frequency power to the electrodes. In order to increase the voltage, it is necessary to make the characteristic impedance of the feed line Q41 three times lower than the plasma impedance of the plasma generation electrode. Therefore, it is difficult to select a single line with the desired characteristic impedance. However, by connecting multiple feed lines with a certain characteristic impedance in parallel (two lines in the device shown in Figure 4), the combined specific impedance area and large volume plasma impedance can be reduced to a low value. It can be set to a similar value. In addition, for the same reason, it is possible to make the feed line a pure resistance with a ratio of the reactance to the resistance of the sending end impedance of 1 or less (the equipment shown in Figure 4 is required, and the 6 ζ reactance is zero). Desirable. There are two cases when this pure resistance occurs. One is when the sending end becomes a valley in the voltage absolute temporary book distribution, and the other is when it becomes a peak VC. Therefore, the pure resistance A similar result can be obtained even if the length Vcm is an integer multiple of 1/2 of the road wavelength, but this is not desirable because the transmission loss increases as the line becomes longer. This is desirable because the voltage at the receiving end of the feeder line is higher than the voltage at the sending end.

The above electrical characteristics can be easily considered and confirmed by plotting them on a Smith chart, and the plotting on the Smith chart can also be used as a simple design means. In other words, is the plasma impedance determined by the shape of the plasma generation electrode? By estimating it, plotting it on a Smith chart, and rotating it, you can easily find the length of the feed line for matching. In this way, in the next state where the sending end impedance is almost pure resistance, can we use an existing matching box to match it? Take. In addition, when you want to change the plasma state or when the shape of the plasma generation electrode is complicated and calculations are difficult, it is not easy to match by changing the length of the feeder line, so use it in conjunction with an existing matching box. This is desirable.

If the above measures are implemented comprehensively, it is possible to perform power supply and matching at the same time using inexpensive power supply lines, allowing high-rise A power supply from high-frequency power supply equipment. The plasma can be efficiently supplied to the plasma generation electrode, and the uniformity of the generated plasma can be improved.

Effects of the Invention In the low-temperature plasma generation device of the present invention, the radio waves generated between the plasma generation electrodes do not leak into the external space other than between the electrodes, electrostatically couple with surrounding metals, and cause discharge, and the plasma is generated outside the electrodes. The high frequency redundant supply to the electrodes is improved, there is no local overheating of the power supply line, and the plasma generation state is extremely uniform and efficient. It is possible to provide processing effects extremely uniformly and efficiently.

[Brief explanation of the drawing]

FIG. 1 shows an example of a plasma generation electrode applied to an embodiment of the present invention, where the figure shows a front view, (Bl shows a side view, and FIG. 2 shows another example of the plasma generation electrode, and the figure shows a front view. figure,
(Bl is a side view, FIG. 3 is a perspective view showing still another example of the plasma generating electrode, and FIG. 4 is a low temperature plasma generating liquid of an embodiment of the present invention using the plasma generating electrode shown in FIG. 1. An example of a low-temperature plasma processing apparatus for processing sheet-like materials incorporating @ is shown;
-I line sectional view, Figure 5 shows an example of a conventional device, (5)
6 is a schematic side view, (C) is a schematic front view, and FIG. 6 is a diagram showing the water absorption performance value in the width direction of the treated fabric. Ql), (15a), (15b), (19a),
(19b) - High voltage application electrode plate, (12a), (
12b), (16a), (16b), K) - Ground electrode plate, μs, C171, @ Katana... Plasma generation ring 6.041. α~, @, Φ...Feed line, (to)...
Treatment chamber, 4... High frequency power supply device, ■... Matching box.

Claims (1)

[Claims] 1. In a low-temperature plasma generation device that generates low-temperature plasma by high-frequency discharge under low pressure, a plasma generation electrode consisting of a high voltage application electrode and a ground electrode facing each other at a constant interval is connected to the high voltage application electrode. In order to supply high-frequency power to the plasma generating electrode, the internal conductor of the power supply line is connected to a high voltage. Connect the external conductor to the application electrode and the ground electrode at the shortest distance, and connect the feed line so that its characteristic impedance is 3 times the plasma impedance of the plasma generation electrode.
1. A low-temperature plasma generation device, characterized in that one or more wires are connected in parallel so that the value is lower than double, and the length is such that the ratio of reactance to resistance at the sending end impedance is 1 or less.