JP2002252269A - Aluminum nitride ceramics electrode built-in member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve durability of a ceramics electrode built-in member used for a semiconductor manufacturing apparatus, a liquid crystal manufacturing apparatus and so on, and specifically to provide an aluminum nitride ceramics electrode built-in member used for a heater which can uniformly heat a wafer, a liquid crystal display substrate and so on by electric heating, an electrostatic chuck which can fix an object by an uniform electrostatic attraction, or a high frequency power applying susceptor which can apply uniform high frequency power. SOLUTION: This member has a built-in metal electrode of which the cross- section aspect ratio is 2-8, and an aluminum nitride ceramics electrode is used as the built-in metal electrode.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum nitride ceramic electrode built-in member used in a semiconductor manufacturing apparatus or a liquid crystal manufacturing apparatus, and more particularly, to a semiconductor manufacturing apparatus or a liquid crystal manufacturing apparatus, and more particularly, to a wafer mounting apparatus. The present invention relates to a member with a built-in electrode made of aluminum nitride ceramics, such as a heater, an electrostatic chuck, and a susceptor for applying a high frequency, used for processing a liquid crystal display substrate and the like.

[0002]

2. Description of the Related Art In a semiconductor manufacturing apparatus, when a wafer or the like is subjected to processing such as plasma etching, CVD, or ion plating, a planar heater is used as a member for heating the wafer. Further, as a wafer fixing member, an electrostatic chuck or a susceptor for applying a high frequency is frequently used. Similar members are used in a liquid crystal manufacturing apparatus.

[0003] Ceramics are used as material for these heaters, electrostatic chucks, susceptors for high frequency application and the like which are excellent in corrosion resistance, wear resistance, accuracy and the like. Among these, aluminum nitride ceramics are particularly frequently used from the viewpoints of mechanical strength, hardness, and excellent corrosion resistance to halogen-based gases used in semiconductor manufacturing equipment and the like. Further, the structure of the heater or the like generally has a metal electrode built in a ceramic substrate.

[0004] These ceramic electrode built-in members,
Usually, it is obtained by the following production method. As described above, the heater, the electrostatic chuck, and the high-frequency application susceptor differ only in the operation and shape of the metal electrode, and the respective structures and manufacturing methods are basically the same. Therefore, a heater will be described below as an example.

For example, in a sheet forming method, first,
A metal electrode is provided on a ceramic green sheet laminated to a predetermined thickness by a doctor blade, and a ceramic heater cover portion having a predetermined thickness is laminated thereon by heat molding. Then, an electrode terminal is provided on the obtained laminate so as to be connected to the metal electrode, degreased under predetermined conditions, and then sintered at a predetermined temperature by a hot press or the like to obtain a heater. In this sheet forming method, screen printing of a conductive paste is generally used as a method of providing a metal electrode on a green sheet.

Another method of manufacturing the heater is to obtain a heater as shown in FIGS. 2 (a) and 2 (b).
Are buried, holes 13 for electrode terminals are provided, and then sintered by hot pressing to obtain ceramic substrate 1.
There is a method of incorporating it in the device.

[0007]

However, the formation of the metal electrode by the screen printing requires that the conductive paste having a small thickness is repeatedly printed. Therefore, each time printing is performed repeatedly, it is required that the printing position be adjusted with high accuracy, and the work process also requires time. In addition, when the thickness of the printed film becomes non-uniform, it becomes difficult to control the total resistance value of the metal electrode, and the resistance of each part of the metal electrode also becomes non-uniform. In some cases, the metal electrode or the ceramic substrate was damaged.

A heater using a coil-shaped metal electrode 12 as shown in FIGS. 2A and 2B has a large surface area of a heating element, so that the in-plane temperature of the heater cover surface is made uniform. be able to. However, in such a heater, since the coil diameter of the metal electrode 12 is large, it is necessary to increase the thickness of the ceramic substrate, and as a result,
This leads to a problem that the heat capacity increases and the response at the time of temperature control decreases.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned technical problems, and has improved the durability of a ceramic electrode-containing member used in a semiconductor manufacturing apparatus, a liquid crystal manufacturing apparatus, and the like. A heater that can uniformly heat a wafer, a liquid crystal display substrate, or the like by electric heat, an electrostatic chuck that can fix electrostatically with a uniform suction force, or a high-frequency application that can uniformly apply high frequency It is an object of the present invention to provide an aluminum nitride ceramic built-in electrode member such as a susceptor.

[0010]

An aluminum nitride ceramic electrode built-in member according to the present invention is a member having a built-in metal electrode, wherein the aspect ratio of the cross section of the metal electrode is 2 or more and 8 or less. And When the aspect ratio is within the above range, strong adhesion between the aluminum nitride ceramics substrate and the metal electrode can be maintained, and current resistance in each portion of the metal electrode is uniformly maintained. Thus, a highly durable aluminum nitride ceramic electrode built-in member can be obtained.

It is preferable that the metal electrode is mainly composed of tungsten. This is in consideration of the fact that the coefficient of thermal expansion is close to that of the aluminum nitride ceramics as the substrate.

Further, in the present invention, it is preferable that the major axis of the cross section of the metal electrode is parallel to the surface of the ceramic substrate. Since the metal electrode is built in a flat state with respect to the ceramic substrate, heater heating or the like can be uniformly applied to a wafer or the like placed on the surface of the ceramic substrate. Further, the ceramic electrode-containing member can be made thinner than in the case where a conventional coil-shaped electrode is incorporated.

Further, it is preferable that the metal electrode is covered with an aluminum nitride ceramic substrate without any gap. If there is a gap between the metal electrode and the aluminum nitride ceramic substrate, the current resistance in each part of the metal electrode is likely to be non-uniform, and the durability of the aluminum nitride ceramic electrode built-in member is reduced. It is.

Further, the aluminum nitride ceramic covering the metal electrode has a density of 3.1 g / cm ³ or more,
Further, it is preferable that the thermal expansion coefficient is 6.0 × 10 ⁻⁶ / ° C. or less and the thermal conductivity is 50 W / m · K or more. By using the aluminum nitride ceramics corresponding to the above physical properties, it is possible to uniformly perform actions such as heating of the heater on the ceramics substrate, and to obtain a highly durable aluminum nitride ceramic electrode built-in member.

The electrode built-in member made of aluminum nitride ceramic according to the present invention is used for causing the metal electrode to act as a resistance heating element or for generating static electricity by applying a DC or AC current to the metal electrode. Alternatively, it is preferably used to apply a high frequency to the metal electrode. These are suitable uses of the electrode-containing member made of aluminum nitride ceramics according to the present invention.

[0016]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 (a) (b)
1 shows an example of the structure of a heater which is an electrode-containing member made of aluminum nitride ceramics according to the present invention.

The aluminum nitride ceramic heater shown in FIGS. 1A and 1B has a metal electrode 2 built in an aluminum nitride ceramic substrate 1. An electrode terminal is connected to the metal electrode 2 through a hole 3 for the electrode terminal on the surface of the ceramic substrate serving as a heater base.
It has a structure in which a current is supplied from outside through the electrode terminals.

In the above description, the heater has been described. However, the electrostatic chuck and the susceptor for applying a high frequency have basically the same structure as that described above, as an aluminum nitride ceramic electrode built-in member. Therefore, the aluminum nitride ceramics electrode built-in member according to the present invention can also obtain members other than the heater by the same manufacturing method. Will be described.

The aluminum nitride ceramic heater according to the present invention can be obtained by using an ordinary method for manufacturing a ceramic heater. For example, the following manufacturing method is preferable. In the method of manufacturing the aluminum nitride ceramic heater shown in FIG. 1, first, a groove for providing a metal electrode 2 is formed on an aluminum nitride ceramic substrate 1 serving as a heater cover in accordance with the electrode pattern shape. After the metal electrode 2 is provided in the groove, the heater cover and the aluminum nitride ceramic substrate serving as a heater base are laminated with a bonding agent.
Next, an electrode terminal for supplying a current from the outside is connected to the metal electrode 2 through an electrode terminal hole 3 provided in the heater base in advance. By subjecting the laminate of the aluminum nitride ceramics substrate 1 in which the metal electrode 2 is incorporated to a bonding heat treatment, an aluminum nitride ceramics heater is obtained.

The metal electrode 2 used in the present invention is obtained by heating a metal wire with a flame burner and bending it into a predetermined shape, or a thin film obtained by subjecting a thin metal plate to laser processing or punching. , A mesh or the like that has been previously processed into a metal electrode pattern shape is used. In this case, by using the conductive paste together, it is possible to improve the adhesion to the groove and the filling degree.

As shown in FIG. 1C, when the metal electrode 2 is embedded in the aluminum nitride ceramic substrate 1, the aspect ratio of its cross section, that is, the ratio of the length of the major axis to the minor axis, is obtained. (L / H) should be 2 or more and 8 or less. When the aspect ratio is less than 2, a gap may be formed between the aluminum nitride ceramic substrate 1 and the metal electrode 2. On the other hand, when the aspect ratio exceeds 8, the metal electrode 2 is easily damaged, and
The heater is damaged by local abnormal heat generation, and the durability of the heater is reduced.

Next, the material of the metal electrode 2 is preferably a material having resistance as a heating element and having a melting point higher than a desired heating temperature. Further, it is particularly preferable that the material of the metal electrode 2 is close to the value of the coefficient of thermal expansion of the aluminum nitride ceramics as the substrate. In the use state of the heater, the aluminum nitride ceramic substrate 1 is expanded by being heated together with the metal electrode 2. Therefore, if the difference in thermal expansion coefficient between the metal electrode 2 and the aluminum nitride ceramic substrate 1 is large,
This is because stress is generated at the interface and the aluminum nitride ceramic substrate 1 may be damaged.

Therefore, the material of the metal electrode 2 is
For example, tungsten (W), molybdenum (Mo), platinum (Pt), silver (Ag), and the like, and a compound containing these can be used. Among these, those containing tungsten as a main component are particularly preferable in consideration of the heat treatment temperature for joining exceeding 1500 ° C., the value of the thermal expansion coefficient of aluminum nitride ceramics, and the like.

The cross-sectional shape of the metal electrode 2 is not particularly limited, such as an ellipse, a capsule, or a rectangle. However, as described above, the aspect ratio of the cross section is 2 or more and 8 or less, and the major axis of the metal electrode 2 Preferably, it is parallel to the surface of the first. For example, FIG. 1C shows the metal electrode 2 having an elliptical cross-sectional shape.
Is preferably parallel to the surface of the aluminum nitride ceramics substrate 1. As shown in FIG. 1B, since the metal electrode 2 is built in the aluminum nitride ceramic substrate 1 in a flat state, a wafer or the like placed on the surface of the aluminum nitride ceramic substrate 1 can be uniformly formed. Can be heated. FIG.
As compared with the case where the conventional coil-shaped metal electrode 12 as shown in (b) is incorporated, the ceramic electrode-containing member can be made thinner.

It is preferable that the metal electrode 2 be covered with the aluminum nitride ceramic substrate 1 without any gap. If there is a gap, the gas present in that portion expands due to the heating of the heater, and the stress causes cracks in the aluminum nitride ceramics substrate 1 and causes damage to the metal electrode 2. Alternatively, the gas chemically reacts, and a stress is generated inside the heater due to a difference in thermal expansion between a reactant and an unreacted material, cracks may occur in the aluminum nitride ceramics substrate 1, and the heater may be damaged. This causes the durability to decrease.

The aluminum nitride ceramic used in the present invention preferably has a density of 3.1 g / cm ³ or more. Since the aluminum nitride ceramic heater is sometimes used under a fluorine-based plasma, the heater needs to have high resistance to the fluorine-based plasma. Aluminum nitride ceramics are materials with high resistance to fluorine-based plasma among ceramics, but when the density is low, the specific surface area increases,
The amount of reactants generated on the surface increases, causing particles to be generated. When the density is low, the fluorine-based plasma passes through the aluminum nitride ceramics,
When the metal electrode 2 touches the metal electrode 2, the metal electrode 2 is corroded and causes a short circuit. Therefore, the density of the aluminum nitride ceramic is preferably not less than 3.1 g / cm ^3, more preferably not less than 3.2 g / cm ³ .

It is preferable that the coefficient of thermal expansion of the aluminum nitride ceramic is 6.0 × 10 ⁻⁶ / ° C. or less. As described above, from the viewpoint of preventing the aluminum nitride ceramic substrate 1 from being damaged, it is preferable that the coefficient of thermal expansion between the aluminum nitride ceramic and tungsten used as the metal electrode 2 be close to each other. Therefore, aluminum nitride ceramics have a thermal expansion coefficient of 6.
It is preferably at most 0 × 10 ⁻⁶ / ° C., 3.8 × 1
More preferably 0 ^-6 / ° C. or more 5.5 × 10 ^-6 / ℃ or less.

Further, the thermal conductivity of the aluminum nitride ceramic is preferably at least 50 W / m · K. The temperature response of a ceramic heater depends not only on the heat capacity but also on the thermal conductivity of the ceramic. When the thermal conductivity is low, the in-plane temperature difference on the heater cover surface increases, and in some cases, the temperature The heater is damaged due to the difference in thermal expansion of the aluminum nitride ceramic substrate 1 caused by the difference. Therefore, the thermal conductivity of the aluminum nitride ceramic is preferably 50 W / m · K or more, more preferably 90 W / m · K or more.

Next, in the groove processing, after the surface of the aluminum nitride ceramic substrate serving as the heater cover is ground, a groove corresponding to the pattern shape of the metal electrode 2 is formed on the surface by machining, sandblasting or the like. It is necessary that the cross-sectional area of the groove be such that the metal electrode 2 is deformed by the pressure at the time of joining and fits in that portion. That is, it is preferable that the cross-sectional area of the heating element wiring is equal to or slightly smaller than that of the heating element wiring so that the metal electrode 2 is compressed and embedded.
Here, in the aluminum nitride ceramic substrate serving as a heater base, after the surface is ground, a hole 3 for incorporating an electrode terminal in a later step is processed and provided.

Then, the heater base and the heater cover are laminated via a bonding agent. The bonding agent may be a ceramic bonding agent containing a general glass component, but a heater used in a semiconductor manufacturing apparatus or the like includes:
A bonding agent that is resistant to fluorine-based plasma because it is exposed to fluorine-based plasma is preferred. For example, it is preferable to use an aluminum or / and yttrium-based compound.

The bonding agent is applied on a substrate by forming a paste and performing screen printing, or by dispersing in an organic solvent such as alcohol and spraying. And
If necessary, degreasing is performed under the conditions usually performed. In general, heating at 400 ° C. or higher is performed to ensure sufficient bonding strength. Next, the heater base to which the bonding agent has been applied and the heater cover are overlapped, and necessary electrode terminals and the like are incorporated into the electrode terminal holes 3 provided in the heater base in advance.

The bonding is performed by heat-treating the laminated aluminum nitride ceramic substrate 1 via a bonding agent. In order to increase the bonding strength, it is preferable to perform heat treatment under pressure, for example, using a hot press,
Heat treatment is performed by applying pressure from the outside. In the case of joining by hot pressing, although it depends on the heat treatment temperature and pressure,
Bonding can be performed without necessarily using a bonding agent.

Also, hot pressing is an effective means for filling the metal electrode 2 into the groove without gaps at the same time as the joining. In this case, the pressure depends on the diameter and length of the heating element wiring, but is usually 50 kg / cm ² or more and 500 kg / c.
m carried out in ² or less. When the pressure is less than 10 kg / cm ² , the metal electrode 2 such as a metal wire, a thin film, and a mesh does not deform sufficiently, so that a gap is formed between the metal electrode 2 and the groove. on the other hand,
When the pressure exceeds 500 kg / cm ^2, there is a possibility that the ceramic substrate may be damaged.

The heat treatment temperature is 1400 ° C. or more and 1950 ° C.
The following is preferred. If the treatment temperature is lower than 1400 ° C., the grain growth of the bonding agent hardly occurs, and a good bonding state cannot be obtained. Further, since the metal electrode 2 is not sufficiently deformed, a gap is generated between the metal electrode 2 and the groove. On the other hand, if the processing temperature exceeds 1950 ° C., the bonding agent grows abnormally,
Problems such as the inability to obtain uniform bonding strength occur. Therefore, the heat treatment temperature is 1400 ° C. or more and 195
0 ° C. or lower, preferably 1600 ° C. or higher and 180 ° C.
It is more preferable that the temperature is 0 ° C. or lower.

In the above embodiment, the heater made of aluminum nitride ceramics has been described as an example.
If the metal electrode 2 is formed in a comb shape, for example, an electrostatic chuck made of aluminum nitride ceramics can be obtained.

Accordingly, the electrode-containing member made of aluminum nitride ceramics according to the present invention obtained as described above can be used to make the metal electrode function as a resistance heating element or to apply a DC or AC current to the metal electrode. To generate static electricity by
In order to apply a high frequency to the metal electrode, it can be suitably used.

[0037]

EXAMPLES Hereinafter, the present invention will be described more specifically based on examples, but the present invention is not limited to the following examples. Example 1 Aluminum nitride ceramics having a diameter of 210 mm and a thickness of 5 mm serving as a heater cover (Y as an auxiliary agent)
₂ O ₃ with an external rate of 1% by weight)
1.1m width according to the shape of the wiring pattern of the metal electrode
A groove having a depth of 150 μm and a depth of 150 μm was formed by machining. A 0.5 mm diameter tungsten wire processed into the shape of the wiring pattern of the metal electrode was fitted into the groove and fixed. After aluminum nitride ceramics having a diameter of 210 mm and a thickness of 5 mm serving as a heater base (Y ₂ O ₃ is added as an auxiliary agent at an external ratio of 1% by weight), the surface is ground.
A bonding agent paste of AlN / Y ₂ O ₃ / Li ₂ O = 100/10/1 is applied by screen printing so that the thickness after degreasing becomes 30 μm, and degreased at 600 ° C. for 1 hour in the air. Was. The superposed heater cover and said heater base, under pressure 0.1 t / cm ^2, by hot pressing, under a nitrogen atmosphere for 3 hours bonding heat treatment at 1800 ° C.. Thereafter, the surface of the heater cover is adjusted to a flatness of 10 μm.
m to obtain a heater made of aluminum nitride ceramics as shown in FIGS. 1 (a) and 1 (b). The produced heater was heated to 600 ° C. under a reduced pressure of 0.01 torr, and the in-plane temperature difference of the heater cover surface was measured. The heater was cut in the thickness direction, and the aspect ratio of the cross section of the tungsten electrode was determined. Table 1 shows the measurement results.
Shown in

Comparative Example 1 An aluminum nitride ceramics heater was manufactured in the same manner as in Example 1 except that the pressing condition in the pressure heat treatment was set to 0.04 t / cm ² . The produced heater was set at 0.01 t in the same manner as in Example 1.
The substrate was heated to 600 ° C. under a reduced pressure of orr, and the in-plane temperature difference of the heater cover surface was measured. Also, the aspect ratio of the tungsten electrode cross section was determined in the same manner as in Example 1. Table 1 shows the measurement results. The heater was found to have a gap between the tungsten electrode and the aluminum nitride ceramics substrate, and was broken 20 hours after the start of heating of the heater, and did not operate as a heater.

Comparative Example 2 An aluminum nitride ceramic heater was manufactured in the same manner as in Example 1 except that the pressing condition in the pressure heat treatment was set at 0.6 t / cm ² . The produced heater was set at 0.01 t in the same manner as in Example 1.
The substrate was heated to 600 ° C. under a reduced pressure of orr, and the in-plane temperature difference of the heater cover surface was measured. Also, the aspect ratio of the tungsten electrode cross section was determined in the same manner as in Example 1. Table 1 shows the measurement results. This heater was found to have local abnormal heat generation, and was broken four hours after the start of heating of the heater, and did not operate as a heater.

[0040]

[Table 1]

As shown in Table 1, in the heater of Example 1, the aspect ratio of the cross section of the tungsten electrode was 6.60.
It was recognized that the in-plane temperature difference was smaller than Comparative Example 1 having an aspect ratio of less than 2 and Comparative Example 2 having an aspect ratio of more than 8. In addition, when the cross section of the heater of Example 1 was observed, there was no gap between the tungsten electrode and the aluminum nitride ceramics substrate, and both were in close contact. On the other hand, in the heater of Comparative Example 1, as described above, a gap was observed between the tungsten electrode and the aluminum nitride substrate. Further, the heater of Comparative Example 2 had no gap between the tungsten electrode and the aluminum nitride ceramics substrate and was in close contact with each other, but had a large aspect ratio of 9.24, and the tungsten electrode was flat.
The spacing between the electrode wirings in the plane was also uneven. Further, when the heater was operated, the heater of Example 1 was operating without change even after 1000 hours from the start of operation, but the heater of Comparative Example 1 was damaged after 20 hours and did not operate as a heater. Was. Further, the heater of Comparative Example 2 was damaged four hours after the occurrence of local abnormal heat generation, and did not operate as a heater.

From this, it can be understood that the aluminum nitride ceramic heater having a tungsten electrode having an aspect ratio of 2 or more and 8 or less can uniformly heat the surface of the heater cover without causing abnormal heat generation.

[0043]

As described above, the electrode built-in member made of aluminum nitride ceramics according to the present invention can easily control the electric resistance and the like and can be made thinner than the conventional one. Further, the durability can be improved. Further, by using the aluminum nitride ceramics electrode built-in member according to the present invention, in processing a wafer, a liquid crystal display substrate, or the like in a semiconductor manufacturing apparatus, a liquid crystal manufacturing apparatus, or the like, the heating or the attraction force and the applied electromagnetic wave are made uniform. And the yield of semiconductor or liquid crystal production can be improved.

[Brief description of the drawings]

FIG. 1 (a) is a perspective view from the top, schematically showing an example of an aluminum nitride ceramics heater according to the present invention. (B) It is AA 'sectional drawing of FIG.1 (a). FIG. 2C is an enlarged view of the metal electrode shown in FIG.

FIG. 2 (b) is a perspective view from the top, schematically showing an example of a conventional ceramic heater. (B) It is BB 'sectional drawing of FIG.2 (a).

[Explanation of symbols]

 Reference Signs List 1 aluminum nitride ceramic substrate 2 metal electrode 3, 13 hole for electrode terminal 11 ceramic substrate 12 coiled metal electrode

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05B 3/20 328 C04B 35/58 104D 104Q 104Y (72) Inventor Mitsuhiro Fujita 30 Soya, Hadano-shi, Kanagawa Toshiba (72) Inventor, Noriaki Kashiwa, 30 Soya, Hadano-shi, Kanagawa Prefecture Toshiba Ceramics, Inc. Development Research Laboratory F-term (reference) 3K034 AA02 AA10 AA16 AA21 AA32 AA33 AA34 AA37 BA06 BA14 BA20 BB06 BB14 BC04 BC15 BC16 CA02 CA15 CA18 CA19 CA20 CA22 CA27 CA29 HA01 HA10 JA01 JA10 3K092 PP20 QA05 QB02 QB26 QB32 QB33 QB40 QB44 QB62 QB73 QB75 QC02 QC16 QC20 QC58 QC59 RF03 RF11 RF25 RF26 VV22 4G001 BC01 BC01 BC36 BC31 BC36 BD03 BD05 BD38 BE32 BE33 5F031 HA02 HA17 HA18 HA37

Claims (6)

[Claims] 1. A member having a built-in metal electrode, wherein an aspect ratio of a cross section of the metal electrode is 2 or more and 8 or less. 2. The electrode-containing member according to claim 1, wherein the metal electrode is mainly composed of tungsten. 3. The aluminum nitride ceramic electrode-containing member according to claim 1, wherein a major axis of a cross section of the metal electrode is parallel to a surface of the aluminum nitride ceramic substrate. 4. The built-in aluminum nitride ceramic electrode according to claim 1, wherein said metal electrode is covered with an aluminum nitride ceramic substrate without any voids. Element. 5. The aluminum nitride ceramic substrate covering the metal electrode has a density of 3.1 g / cm ³ or more, and
Thermal expansion coefficient 6.0 × 10 ^-6 / ° C or less, and thermal conductivity 5
The electrode built-in member made of aluminum nitride ceramics according to any one of claims 1 to 4, wherein the electrode built-in electrode has a power of 0 W / m · K or more. 6. To cause the metal electrode to act as a resistance heating element, or to generate static electricity by applying a DC or AC current to the metal electrode,
The electrode-containing member according to any one of claims 1 to 5, wherein the member is used to apply a high frequency by the metal electrode.