JP2005354011A - Plasma treatment apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide plasma treatment apparatus in which a pair of opposing electrodes are easily attached to a solid dielectric member bonded to at least one of opposing surfaces of the electrodes and easily removed from the member, and the member does not fall off during plasma treatment, and a gap is formed between the electrodes and the member during plasma treatment, in which discharge does not occur. <P>SOLUTION: Plasma treatment apparatus has a pair of opposing electrodes and a solid dielectric member bonded to one of opposing surfaces of the electrodes, wherein suction means is provided for bonding between at least one of electrodes and the solid dielectric member by vacuum suction. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

In the present invention, it is easy to attach and detach the pair of opposing electrodes and the solid dielectric member bonded to at least one of these opposing surfaces, and the solid dielectric member does not fall off during the plasma treatment. The present invention relates to a plasma processing apparatus in which a gap is formed between an electrode and a solid dielectric member during plasma processing, and no discharge is generated in the gap.

Plasma processing is known as a method for effectively modifying the surface of a plastic substrate or cleaning and removing organic substances adhering to a semiconductor substrate or the like. As a plasma processing apparatus used for plasma processing of such an object to be processed, for example, Patent Document 1 discloses a plasma having an electrode in which a solid dielectric is disposed on the surface of at least one of opposing electrodes. A processing device is disclosed. In this plasma processing apparatus, gas is introduced between opposing parallel electrodes, a voltage is applied between the electrodes to excite the plasma, and this plasma is applied to an object to be processed positioned between the opposing electrodes. Perform surface modification of the workpiece.

In a conventional plasma processing apparatus in which a member made of a solid dielectric is disposed on the opposing surface of such an electrode, the solid dielectric member is applied between the opposing electrodes when performing plasma processing on an object to be processed. It is formed for the purpose of preventing abnormal discharge from occurring between the electrodes due to the applied voltage. However, since this solid dielectric is directly exposed to plasma during plasma processing, it is easily damaged and needs to be replaced periodically. was there.

As a joining method for making the electrode and the solid dielectric member exchangeable, for example, a method of joining via an adhesive layer is performed. However, when the solid dielectric member is bonded to the opposing surface of the electrode via the adhesive layer, the solid dielectric member is obtained when the opposing surface of the electrode and the solid dielectric member are bonded with a strong adhesive force. There is a problem that it becomes very difficult to replace the battery. On the contrary, if the opposing surface of the electrode and the solid dielectric member are bonded with a weak adhesive force, the solid dielectric member may fall off during the plasma treatment. Further, even if the solid dielectric member does not fall off, it moves, or a gap is formed between them, and a discharge (so-called back discharge) occurs in the gap, so that a uniform plasma treatment is performed on the workpiece. There was a problem that I could not.

Moreover, as another joining method for making the electrode and the solid dielectric member replaceable, for example,
As shown in FIG. 2, the insertion portion 24 and the insertion portion 24 of the housing 21 in which a wedge-shaped insertion portion 24 is formed so that the opposing surface 23 of the electrode 22 embedded therein is exposed. A method of fixing a solid dielectric member having substantially the same cross-sectional shape by wedges is known. FIG. 2 is a cross-sectional view schematically showing an example of an electrode portion in a conventional plasma processing apparatus.
In the plasma processing apparatus as shown in FIG. 2, by removing the solid dielectric member wedged on the insertion portion 24 of the housing 21, the solid dielectric member damaged by the plasma processing, such as deterioration or dirt, can be easily obtained. Can be exchanged. However, in the plasma processing apparatus shown in FIG. 2, the solid dielectric member is fixed to the insertion portion 24 of the housing 21 by its rigidity and disposed on the facing surface 23 of the electrode 23. However, the plasma processing is repeatedly performed. The solid dielectric member may be deformed, and a large gap may be formed between the facing surface 24 of the electrode 23 and the solid dielectric member. In particular, when the pair of electrodes 23 are arranged vertically, the solid dielectric member wedged on the insertion portion 24 of the housing 21 arranged on the upper side is immediately bent due to its own weight and dropped or peeled off. Or a large gap is formed in the vicinity of the center due to deflection, and back discharge occurs in the gap formed between the electrode and the solid dielectric member during the plasma treatment, so that a uniform plasma treatment is applied to the workpiece. There was a problem that could not be done. Such a problem is particularly noticeable when the electrodes and the solid dielectric member become large in order to perform plasma processing on a large workpiece.

Japanese Patent Laid-Open No. 7-85997

In view of the above situation, the present invention makes it easy to attach and detach a pair of opposing electrodes and a solid dielectric member bonded to at least one of these opposing surfaces, and the solid dielectric member falls off during plasma processing. In addition, it is an object of the present invention to provide a plasma processing apparatus in which a gap is formed between an electrode and a solid dielectric member during plasma processing and no discharge is generated in the gap.

The present invention is a plasma processing apparatus having a pair of electrodes facing each other and a solid dielectric member bonded to a facing surface of the electrodes, and a vacuum is formed between at least one of the electrodes and the solid dielectric member. It is a plasma processing apparatus having suction means for joining by suction.
The present invention is described in detail below.

The plasma processing apparatus of the present invention has a pair of electrodes facing each other and a solid dielectric member joined to at least one facing surface of the electrodes.
The pair of electrodes facing each other is not particularly limited, and examples thereof include simple metals such as iron, copper, and aluminum; alloys such as stainless steel and brass; and those made of intermetallic compounds.

The shape of the electrode is not particularly limited, but a plate shape such as a disk shape or a square plate shape is preferable. As will be described in detail later, it is easy to perform a process of joining the electrode and the solid dielectric member by vacuum suction by the suction means.

The material constituting the solid dielectric member is not particularly limited. For example, plastics such as polytetrafluoroethylene and polyethylene terephthalate; ceramics such as glass, silicon dioxide, aluminum oxide, zirconium dioxide, and titanium dioxide; barium titanate and the like And the double oxide.

In the plasma processing apparatus of the present invention, the solid dielectric member is disposed on the facing surfaces of the pair of electrodes facing each other so as to cover the entire facing surfaces of the electrodes. If there is a portion that is not covered with the solid dielectric member on the opposing surface of the electrode, abnormal discharge occurs between the electrodes when a voltage is applied between these electrodes in order to perform plasma treatment of the workpiece. This is because uniform plasma treatment cannot be performed on the workpiece.

The plasma processing apparatus of the present invention has suction means for joining at least one of the electrodes and the solid dielectric member by vacuum suction.
The suction means is not particularly limited as long as it can vacuum-suck between the electrode and the solid dielectric member, and includes, for example, a conventionally known vacuum pump.

In the plasma processing apparatus of the present invention, the suction means may be connected so as to vacuum-suck between one of the electrodes and the solid dielectric member, and between the both electrodes and the solid dielectric member. May be connected so as to be vacuum-sucked.
When the pair of opposed electrodes are arranged in the vertical direction, the suction means is connected so as to vacuum-suck at least between the upper electrode and the solid dielectric member. The upper solid dielectric member bends and falls off due to its own weight, or cracks occur, and a gap is formed on the opposing surface of the electrode due to the bending, and the solid dielectric is damaged by back discharge of the gap. This is to prevent the occurrence of the problem.
Further, when the pair of opposing electrodes are arranged in the left-right direction, the suction means is connected so as to vacuum-suck between both electrodes and the solid dielectric member. The solid dielectric member disposed on the facing surfaces of both the left and right electrodes bends due to its own weight and falls off or peels off, and a gap is formed with respect to the facing surface of the electrode due to the bending. This is to prevent the solid dielectric from being damaged by the discharge.

The plasma processing apparatus of the present invention in which the electrode and the solid dielectric member are vacuum-sucked and joined by such a suction means is adjusted by adjusting the suction force of the suction means and the opposing surface of the electrode and the solid The bonding strength with the dielectric member can be freely adjusted. Therefore, the solid dielectric member can be firmly bonded to the opposing surface of the electrode during the plasma processing, and the solid dielectric member can be dropped or moved during the plasma processing to leave a gap between the opposing surface of the electrode. Is not formed, and no electric discharge is generated in this gap. On the other hand, by stopping the suction means, the solid dielectric member can be easily removed from the opposing surface of the electrode, and the replacement work of the solid dielectric member becomes very easy.

A method for joining the electrode and the solid dielectric member by vacuum suction using the suction means is not particularly limited. For example, the plasma processing apparatus of the present invention preferably has a structure as shown in FIG. Can be realized.

FIG. 1 is a cross-sectional view showing a preferred embodiment in the vicinity of an electrode of the plasma processing apparatus of the present invention.
The plasma processing apparatus of the present invention shown in FIG. 1 has a pair of electrodes 1 in which a plate-like solid dielectric member 3 is in contact with an opposing surface 2, and suction means (not shown) is provided on the opposing surface 2 of the electrode 1. Are connected to each other, and a discharge space 5 is formed between the upper and lower electrodes 1 and the solid dielectric member 3.

In the plasma processing apparatus of the present invention having such a structure, by operating a suction means (not shown), the groove 4 is vacuum-sucked so that the solid dielectric member 3 is joined to the facing surface 2 of the electrode 1. Yes. Therefore, in the plasma processing apparatus of the present invention shown in FIG. 1, the solid dielectric member 3 can be firmly bonded to the facing surface 2 of the electrode 1 by operating the suction means, and the solid dielectric material is treated during the plasma processing. The body member 3 does not drop off or move to form a gap between the opposing surface 2 of the electrode 1 and discharge does not occur in this gap. On the other hand, by stopping the suction means, the solid dielectric member 3 can be easily removed from the facing surface 2 of the electrode 1, and the replacement work of the solid dielectric member 3 becomes very easy.

The shape of the groove 4 is that the space formed when the solid dielectric member 3 is placed on the facing surface 2 of the electrode 1 is vacuum-sucked by a suction means so that the solid dielectric member 3 faces the facing surface of the electrode 1. It is preferable that only the end on the side connected to the suction means is a groove exposed on the side surface of the electrode 1 so that it can be joined to the suction means. If there is a portion exposed on the side surface of the electrode 1 other than the end portion on the side where the groove portion 4 is connected to the suction means, the electrode 1 and the solid dielectric member 3 are firmly joined by vacuum suction. I can't do that.

Further, the planar pattern of the groove 4 is not particularly limited, and examples thereof include an arbitrary pattern such as parallel lines, spirals, and corrugations. However, the groove 4 is formed on almost the entire opposing surface 2 of the electrode 1. preferable. This is because the solid dielectric member 3 can be sucked with a uniform suction force. Furthermore, although the groove part 4 shown in FIG. 1 is a groove | channel with the substantially square cross-sectional shape, in the plasma processing apparatus of this invention, for example, a cross-sectional shape is a groove | channel of rectangular, V shape, or U shape. Also good.

Such a groove portion 4 can be formed in a desired pattern by performing groove processing such as grinding processing such as conventionally known router processing or sand blast processing on the facing surface 2 of the electrode 1. The preferable lower limit of the depth is 1 μm, and the preferable upper limit is 1000 μm. 1μm
If the thickness is less than 1000 μm, the solid dielectric member 3 may not be bonded to the opposing surface 2 of the electrode 1 with sufficient adsorption force. If the thickness exceeds 1000 μm, the solid dielectric member 3 may be large between the electrode 1 and the solid dielectric member 3. A gap is formed, and discharge may occur in the groove 4.

The plasma processing apparatus of the present invention is not particularly limited to the structure shown in FIG. 1 as long as it can be vacuum-sucked by the suction means between the electrode and the solid dielectric member. A groove connected to the suction means may be formed on the surface of the solid dielectric member facing the electrode, and the groove is formed on both the electrode facing surface and the surface of the solid dielectric member facing the electrode. May be.
As described above, since the plasma processing apparatus of the present invention joins the electrode and the solid dielectric member by vacuum suction using the suction means, the electrode and the solid dielectric can be operated by operating / stopping the suction means. The body member can be easily attached and detached, and the replacement work of the solid dielectric member becomes very easy. In addition, since the solid dielectric member can be firmly bonded to the opposite surface of the electrode while the adsorption means is in operation, even if the electrode and the solid dielectric member are large, the solid dielectric member can be used during plasma processing. The body member does not fall off, the position shift does not occur, and no gap is formed between them, and the plasma treatment can be performed uniformly on the workpiece.

An object to be processed by the plasma processing apparatus of the present invention is held and fixed on the opposing surface of one of the opposing electrodes or the solid dielectric member and is used for the plasma processing. Such an object to be processed is not particularly limited, and examples thereof include a plate-shaped, sheet-shaped or film-shaped resin substrate, a semiconductor wafer and the like that have been conventionally subjected to plasma processing.

The plasma processing apparatus of the present invention is, for example, like the conventional plasma processing apparatus shown in FIG.
The electrode and the solid dielectric member may be embedded in the housing. With such a structure, the electrode can be suitably protected from plasma or the like. In the plasma processing apparatus of the present invention, the insertion portion in which the solid dielectric member of the housing is embedded does not necessarily have a wedge shape like the insertion portion 24 of the housing 21 shown in FIG. For example, the plate-like solid dielectric member may have a rectangular shape in cross section so that the plate-like solid dielectric member can be fitted from a direction perpendicular to the opposing surface of the electrode.
However, even in this case, it is necessary that the solid dielectric member be bonded to the opposing surface of the electrode by vacuum suction between the electrode and the solid dielectric member by the suction means. Therefore, it is preferable that a suction opening penetrating between the electrode and the solid dielectric member is provided on the side surface of the housing, and the suction opening and the suction means are connected.

The material constituting the housing in which the electrode and the solid dielectric member are embedded is not particularly limited, and examples thereof include inorganic materials such as glass and ceramics; organic materials such as fluororesin, nylon, and polyetheretherketone.

The plasma processing apparatus of the present invention introduces a gas between a pair of electrodes facing each other, generates a plasma gas by applying a certain voltage, and holds and fixes on the electrode or the solid dielectric member. Plasma treatment can be performed uniformly on the surface of an object.

The gas is not particularly limited because pulse discharge plasma described later can generate glow discharge plasma without a rare gas, but nitrogen gas, a mixed gas of nitrogen and oxygen, and the like are preferable. Among these, a mixed gas with oxygen has a high organic substance decomposition effect.

While supplying such a gas between the electrodes facing each other, an electric field such as a high frequency, a pulse wave, or a microwave is applied to generate glow discharge plasma, thereby generating a plasma gas.
In this case, the electric field is preferably a pulse electric field, and in particular, a pulse electric field having a rise time and / or a fall time of 10 μs or less is preferable. When the rise and / or fall time of the pulse electric field exceeds 10 μs, the discharge state tends to shift to arc discharge and becomes unstable, and it may be difficult to maintain a high-density plasma state. More preferably, it is 5 μs or less. The shorter the rise time and / or fall time of the electric field, the more efficiently ionization of the gas at the time of plasma generation is performed, and an efficient plasma can be obtained, but at present, a pulse electric field with a rise time of less than 40 ns. It is difficult to realize.
In this specification, the rise time of electrolysis means the time that the voltage (absolute value) continuously increases, and the fall time means the time that the voltage (absolute value) continuously decreases. .

The preferable lower limit of the electric field strength of the electric field is 10 kV / cm, and the preferable upper limit is 1000 kV / c.
m. If it is less than 10 kV / cm, it may take too much time to generate plasma gas, and if it exceeds 1000 kV / cm, arc discharge is likely to occur and it may be difficult to maintain a high-density plasma state. .

A preferable lower limit of the frequency of the electric field is 0.5 kHz. If it is less than 0.5 kHz, the plasma density is low, and it may take too much time to generate plasma gas. An upper limit is not specifically limited, 13.56 MHz currently used regularly, 50 MHz currently used experimentally
However, it is preferably 500 kHz or less in consideration of ease of matching with the load and handleability.

The preferable lower limit of one pulse duration in the pulse electric field is 0.5 μs, and the preferable upper limit is 200 μs. When it exceeds 200 μs, it becomes easy to shift to arc discharge.
In the present specification, one pulse duration means a continuous ON time of one pulse in a pulse electric field composed of repetition of ON and OFF.
Moreover, the preferable lower limit of the OFF time at this time is 0.5 μs, and the preferable upper limit is 1000 μs.
The upper limit is more preferably 500 μs.

Moreover, it does not specifically limit as a speed | rate which supplies the said gas between the electrodes which oppose, What is necessary is just to adjust suitably according to the state of a plasma, process conditions, etc., but a preferable minimum is 1 m / s and a preferable upper limit is 50 m / s. . If it is less than 1 m / s, a current path is likely to be formed, and the discharge may become unstable. A more preferable lower limit is 2 m / s, and a more preferable upper limit is 20 m / sec.

The plasma gas can be generated and used under any pressure, but it is preferable to use it under a pressure near atmospheric pressure because the apparatus configuration can be simplified.
In the present specification, under the pressure near atmospheric pressure is 1.333 × 10 ^{4 to} 10.664 ×.
It means under a pressure of 10 ⁴ Pa. Among these, the range of 9.331 × 10 ^{4 to} 10.9797 × 10 ⁴ Pa, which allows easy pressure adjustment and simplifies the configuration of the apparatus, is preferable. However, when the inside of the apparatus is evacuated after surrounding the entire apparatus with a chamber or the like, the processing gas may be introduced from the vicinity of the electrode within a range in which abnormal discharge does not occur.

The plasma processing apparatus of the present invention has a pair of electrodes facing each other and a solid dielectric member bonded to the facing surface of the electrodes, and a suction means is provided between at least one of the electrodes and the solid dielectric member. Joining is performed by vacuum suction. Such a plasma processing apparatus of the present invention can freely adjust the bonding strength between the opposing surface of the electrode and the solid dielectric member by adjusting the suction force of the suction means. Therefore, the solid dielectric member can be firmly bonded to the opposing surface of the electrode during the plasma processing, and the solid dielectric member can be dropped or moved during the plasma processing to leave a gap between the opposing surface of the electrode. , And back discharge does not occur in this gap. On the other hand, by stopping the suction means, the solid dielectric member can be easily removed from the opposing surface of the electrode, and the replacement work of the solid dielectric member becomes very easy.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.

(Example 1)
A groove portion having a width of 100 μm and a depth of 100 μm is formed on the opposite surface of a flat electrode made of aluminum having a width of 30 mm, a length of 500 mm, and a thickness of 30 mm.
Formed at intervals of m. Further, a flat solid dielectric member made of alumina having a width of 50 mm, a length of 520 mm, and a thickness of 0.5 mm was produced. Two sets of these electrodes and solid dielectric members were prepared.
Then, a solid dielectric member was brought into contact with the opposing surface of the electrode, and a plasma processing apparatus having a structure embedded in a housing made of nylon 66 with a surface opposite to the electrode of the solid dielectric member exposed was produced. Further, a suction opening exposing the groove between the electrode and the solid dielectric member was formed on the side surface of the housing, and the suction opening and the vacuum pump were connected.

As an object to be processed, a polyimide sheet having a width of 25 mm, a length of 450 mm, and a thickness of 50 μm is placed on the upper surface of the lower housing (the upper surface of the solid dielectric member), and in this state, nitrogen gas is used as a gas to face each other. A voltage was applied between the pair of electrodes to generate plasma, and the polyimide sheet was subjected to plasma treatment.

(Comparative Example 1)
Using the plasma processing apparatus having the structure shown in FIG. 2, the width is 25 mm, the length is 450 mm, and the thickness is 50 μm.
The plasma treatment of the m polyimide sheet was performed under the same conditions as in Example 1.

(Comparative Example 2)
Plasma treatment of a polyimide sheet having a width of 25 mm, a length of 450 mm, and a thickness of 50 μm as in Example 1 using a conventionally known plasma processing apparatus in which an electrode and a solid dielectric member are joined via an epoxy adhesive. Was performed under the same conditions as in Example 1.

(1) Evaluation of presence / absence of back discharge Before the plasma treatment performed in Example 1 and Comparative Examples 1 and 2 is repeated to replace the solid dielectric member, the electrode and the solid dielectric member It was confirmed whether back discharge occurred during the period.
The results are shown in Table 1.

(2) Evaluation of easiness of replacement of solid dielectric member Example 1 and Comparative Examples 1 and 2 Check whether the solid dielectric member of the obtained plasma processing apparatus can be easily removed from the opposing surface of the electrode. did.
The results are shown in Table 1 as ◯ when the solid dielectric member could be easily removed and as x when the solid dielectric member could not be easily removed.

From the results shown in Table 1, in the plasma processing apparatus obtained in Example 1, the back discharge occurs between the electrode and the solid dielectric member before the solid dielectric member needs to be replaced. In addition, the solid dielectric member could be easily removed from the opposing surface of the electrode.
In contrast, in the plasma processing apparatus obtained in Comparative Example 1, the solid dielectric member could be easily removed from the opposing surface of the electrode, but the solid dielectric member was bent by the 250th plasma treatment. It was observed that it occurred. At this time, no damage causing cracks was observed on the surface of the solid dielectric member, but burnt or peeling that appears to have caused discharge was observed on the back surface of the solid dielectric member. Furthermore, in the 290th plasma treatment, the solid dielectric member was cracked, and it was necessary to replace the solid dielectric member.
The plasma processing apparatus obtained in Comparative Example 2 did not generate back discharge between the electrode and the solid dielectric member until the solid dielectric member had to be replaced. The body member could not be easily removed from the opposing surface of the electrode, and the electrode was damaged.

According to the present invention, it is easy to attach and detach the pair of opposing electrodes and the solid dielectric member joined to at least one of the opposing surfaces, and the solid dielectric member does not fall off during the plasma processing, In addition, it is possible to provide a plasma processing apparatus in which a gap is formed between the electrode and the solid dielectric member during plasma processing and no discharge is generated in the gap.

It is sectional drawing which shows one preferable embodiment of the electrode vicinity of the plasma processing apparatus of this invention. It is sectional drawing which shows typically an example of the electrode vicinity of the conventional plasma processing apparatus.

Explanation of symbols

1, 22 Electrodes 2 and 23 Opposing surface 3 Solid dielectric member 4 Groove portion 21 Housing 24 Insertion portion

Claims (2)

A plasma processing apparatus having a pair of electrodes opposed to each other and a solid dielectric member joined to a facing surface of the electrodes, wherein at least one of the electrodes and the solid dielectric member are joined by vacuum suction. A plasma processing apparatus having suction means. The plasma processing apparatus according to claim 1, wherein a groove portion is formed on an opposing surface of the electrode and / or a surface of the solid dielectric member facing the electrode, and the groove portion is connected to a suction unit.

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