JP2003213432A - Electrode for plasma cvd apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To uniformize the temperature distribution of a matter to be treated and to miniaturize a plasma CVD apparatus. <P>SOLUTION: A placement plate 12 is arranged opposed to a base part 4 and spaced from a feeder plate 16 on the base part 4. Each end surface of a feeder cylinder 14 comes into contact with one surface of the feeder plate 16 and one surface of an installation plate 12, and electric power is transmitted to the installation plate 12 from the feeder plate through the feeder cylinder 14. A plurality of insulating plates 20, 22 and 24 are stacked around the feeder cylinder 14 between the feeder plate 16 and the installation plate 12 along the longitudinal direction of the feeder cylinder 14. The insulating plates 20 and 24 among the insulating plates 20, 22 and 24 have heat insulation. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode used in a plasma CVD apparatus, for example, a discharge electrode, and more particularly to a heat insulating structure thereof.

[0002]

2. Description of the Related Art Conventionally, a plasma CVD apparatus is provided with a discharge electrode and a counter electrode in a vacuum chamber, a treatment object is brought into contact with the discharge electrode, a reaction gas is introduced into the vacuum chamber, and a high frequency or There is a method in which a direct current voltage is applied to generate plasma between the object to be processed and a counter electrode to ionize and decompose the reaction gas to form a film of a desired component in the reaction gas on the surface of the object to be processed. A substance having a relatively large adsorption energy such as chloride may be used as a film forming material. In this case, in order to reduce impurities such as chlorine contained in the film, the processed product is heated to several hundred degrees or more.

[0003]

However, there is a problem in that when heating is performed at several hundreds of degrees or more, the heat loss from the discharge electrode in contact with the object to be processed is large and the temperature distribution of the object to be processed is not uniform. In order to reduce this heat loss, for example, in order to lower the temperature of the base portion to which the discharge electrode is attached to about 100 degrees Celsius, the distance between the electrode and the base portion may be increased to about 700 mm. It was necessary, the workability was poor, and the size of the entire plasma CVD apparatus was large.

According to the present invention, the temperature distribution of the object to be treated can be made uniform, the workability is good, and plasma CVD is performed.
It is an object of the present invention to provide an electrode for a plasma CVD device that can be downsized.

[0005]

The electrode according to the present invention has a flat power supply plate supported on a base. The power supply plate can be supported on the base via an insulating plate. An electrically conductive flat plate-shaped processed material installation plate is disposed on the side opposite to the base portion with a space provided between the power supply plate and the power supply plate.
Each end surface of the power transmission unit is in contact with one surface of the power supply plate and one surface of the processed material installation plate. The areas of these end surfaces are smaller than the areas of one surface of the power supply plate and one surface of the processed material installation plate. The power transfer unit transfers the power supplied from the power supply plate to the processed product installation plate. A plurality of insulating plates are laminated around the power transfer unit between the power supply plate and the processed material installation plate along the length direction of the power transfer unit. The plurality of insulating plates include those having a heat insulating property.

A plasma CV is used for the electrode thus constructed.
When used in the D device, even if the processed product is heated and the heat is conducted to the processed product installation plate, a heat insulating material is provided in the insulating plate, so the heat is transferred to the base side. It is not conducted, and the temperature distribution of the processed material installation plate can be made uniform. Moreover, it is not necessary to increase the distance between the processed material installation plate and the power feeding plate, and the plasma CV using this electrode is provided.
In addition to improving the workability of manufacturing the D device,
It can be miniaturized.

It is also possible to dispose an insulating plate having a heat insulating property on the side of the power supply plate and the side of the processed material installation plate. When a plurality of insulation plates are configured with only insulation plates having heat insulation properties,
A sharp temperature gradient is generated, and the residual product of the reaction gas is likely to adhere to such a portion. However, if an insulating plate having heat insulating properties is arranged on the power supply plate side and the processed product installation plate side,
A normal insulating plate is present between them, and the presence of this normal insulating plate moderates the temperature gradient. As a result, the deposition of residual products of the reaction gas is reduced.

Of the plurality of insulating plates, the insulating plate having the heat insulating property may be made of quartz glass, and the remaining insulating plates may be made of alumina. Although quartz glass has a good heat insulating property, since it transmits light having a specific wavelength such as infrared rays, alumina is used to prevent such transmission.

The power can be high frequency power. In this case, the power transmission part is formed in a cylindrical shape. The high frequency power flows on the surface of the conductor or the insulator whose impedance is matched by the skin effect. Therefore, since the surface area can be increased by forming the power transmission portion in a cylindrical shape, it is easy to transmit the high frequency that flows due to the skin effect.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION An electrode according to one embodiment of the present invention is
It is used in a plasma CVD apparatus as shown in FIG. This plasma CVD apparatus has a vacuum chamber 2. The vacuum chamber 2 is provided in a sealed state on a base portion, for example, a base portion 4. Although not shown,
An evacuation means such as a vacuum pump is connected to the vacuum chamber 2 so that the interior of the vacuum chamber can be exhausted to a predetermined vacuum degree. Further, although not shown, gas introduction means for introducing the material gas for forming the film or the reaction gas into the vacuum chamber 2, for example, a gas supply source and an introduction passage, and an on-off valve interposed in the middle of this introduction passage. Etc. are also provided. Further, heating means for heating the vacuum chamber 2 from the outside, such as a heater, is also provided.

At a position near the inner surface of the vacuum chamber 2,
For example, a cylindrical ground electrode 6 is provided. A processing object 8 is arranged in the vacuum chamber 2 substantially at the center so as to face the ground electrode 6. The processing object 8 is made of an insulator such as metal or ceramic. The holder 1 is attached to the lower part of the vacuum chamber 2 so as to support the processed object 8.
0 is placed. This attachment holder 10 is used for processing objects 8
It is made of the same material as the object to be processed 8 having a reverse side surface shape in which the width of the lower surface is narrower than that of the upper surface on which is mounted.

The installation plate 12 is placed in contact with the lower surface of the mounting holder 10. The installation plate 12 is a rectangular or circular conductive member having an upper surface and a lower surface whose size is substantially the same as the lower surface of the mounting holder 10. The center of the lower surface of the installation plate 12 is in contact with the power transmission section, for example, the upper end surface of a cylindrical power supply tube 14. The power supply tube 14 extends downward from the upper end surface. The lower end of the power supply tube 14 is in contact with the upper surface of the power supply plate 16. Power supply plate 16
Is also a rectangular or circular conductive member having an upper surface and a lower surface having substantially the same size as the installation plate 12. The power supply plate 16 is arranged on the base portion 4 via an insulator 18. Therefore, the power supply plate 16, the power supply cylinder 14, and the installation plate 12
Are insulated from the base 4. The outer periphery of the insulator 18 is held by the insulator 18. The insulator 18 also has a heat insulating function of preventing the amount of heat of the power supply tube 14 from being transmitted to the base portion 4. Therefore, quartz glass, which is an insulator having excellent heat insulating properties, is used.

The power supply plate 16 is connected to a power source (not shown) and supplies direct-current to high-frequency (for example, MHz) power.
The power is supplied to the installation plate 12 via the power supply tube 14.
Electric power is supplied to the processed object 8 via the mounting holder 10 on the installation plate 12, and the processed object is discharged between the processed object 8 and the ground electrode 6.

When the high frequency power is supplied to the conductor, the power supply cylinder 14 is used in consideration of a so-called skin effect in which only the surface portion of the conductor flows. Further, since the shape of the cross section of the power supply tube 14 is annular, the volume of the power supply tube 14 is small and the amount of heat transfer can be reduced.

The installation plate 12 has a role of enlarging a power supply region in order to spread the power supplied from the power supply cylinder 14 to the entire area of the object to be processed 8, and enlarges a contact area with the mounting holder 10. . Further, it also functions as a load receiving plate that bears the load of the processed object 8 so that the load of the processed object 8 is not applied to the insulating plates 20, 22, 24, etc. described later.

A plurality of, for example, three insulating plates 20, 22, 24 are provided between the power feeding plate 16 and the installation plate 12. Insulation plate 20 arranged in contact with the power supply plate 16
Is not only excellent in insulation against high frequencies, but also excellent in heat insulation, and is made of, for example, quartz glass. Further, the insulating plate 24, which is arranged on the installation plate 12 with a slight gap, is also made of quartz glass. An ordinary insulator, for example, an insulator 22 made of alumina is disposed between the insulators 20 and 24 made of quartz glass. These are formed in a circular shape or a rectangular shape in accordance with the shapes of the power supply plate 16 and the installation plate 12.

In this plasma CVD apparatus, the vacuum chamber 2 is evacuated to a pressure of 0.1 Pa or less, and the vacuum chamber 2 is evacuated.
Is heated from the outside to heat the processed product 8 to a temperature of 800 ° C. or higher. While evacuation is performed, a material gas, for example, a mixture of a chlorine compound material and a reaction gas is introduced into the vacuum chamber 2 so that the pressure in the vacuum chamber 2 is 10 Pa to 100 P.
Adjust to a constant pressure between a. A power of high frequency or the like is applied to the power supply plate 16 to generate plasma 26 between the object to be processed 8 and the ground electrode 6 to excite a self-bias on the surface of the object to be processed 8 to form a film. The introduced material gas and the reaction gas are ionized and decomposed by the plasma 26, and the film is vapor-phase grown in the sheath 28 formed on the surface of the processing object 8 by the action of decomposition, reaction and desorption.

Since the temperature of the processed material 8 is as high as 800 ° C. or higher as described above, the heat loss is large and the temperature distribution of the processed material 8 cannot be made uniform in the conventional electrode structure. In addition, in order to lower the temperature of the base portion 4 to a temperature at which there is no problem, for example, 150 ° C. or lower, the length of the electrode has to be increased. Therefore, the plasma CVD apparatus itself is also large.

Therefore, in the present embodiment, the insulating plates 20 and 24 having a high heat insulating property are used as the heat insulating structure to improve the heat insulating property to reduce the heat loss and to make the temperature distribution of the processed object 8 uniform. In addition, the temperature at the base 4 is lowered. In particular, a normal insulating plate 22 is sandwiched between the insulating plates 20 and 24 to reduce the heat shock.

That is, the installation plate 12 is heated to near 800 ° C, and the mounting holder 10 is heated to 800 ° C or higher. There is a slight gap between the insulating plate 24 and the installation plate 12, and since this gap portion is in a vacuum state, there is no heat conduction and the insulating plate 24 receives heat only by heat radiation. However, since the installation plate 12 is extremely hot, the insulating plate 2 can be heated by only heat radiation.
The amount of heat received by No. 4 is large. If the amount of heat received cannot be significantly reduced, the capacity for heating the processed material 8 becomes large, and the temperature distribution of the processed material 8 cannot be made uniform. Also the base 4
The heat loss in the direction is also large, and the temperature near the base portion 4 cannot be lowered to a safe temperature.

Therefore, in the present embodiment, the insulating plate 24 and the insulating plate 20 below it are made of quartz glass, which is an insulator having a high heat insulating property, and each has a small thickness, for example, 40 mm. Most of the loss is insulated. The thermal conductivity of quartz glass is about 1/10 that of mild steel, and it is very effective for heat insulation. In addition, it has a good insulating property against high frequencies. Therefore, the size of the electrode including the installation plate 12, the power supply tube 14, and the power supply plate 16 can be shortened, and the size of the plasma CVD apparatus can also be shortened.
For example, in the conventional case, the distance between the power feeding plate and the installation plate is 7
Although about 100 mm was required, in this embodiment, the distance between the power feeding plate and the installation plate could be shortened to about 250 mm.

However, quartz glass has a property of transmitting infrared rays. Mild steel is generally used for the installation plate 12 and the like. When mild steel is heated to 700 ° C. or higher, it becomes red hot and emits infrared rays. When this infrared ray is conducted to the base 4 side, the temperature near the base 4 rises. Therefore, in order to block the infrared rays, an insulating plate 22 made of alumina, which blocks infrared rays and has an insulating property against high frequencies, is arranged between the insulating plates 20 and 24.

If only the insulating plates 20 and 24 made of quartz glass are provided, the temperature gradient becomes steep. for that reason,
The insulating plates 20 and 24 may be damaged, and the reaction gas and the material gas are rapidly cooled.
There is a possibility of adhesion to 0 and 24. Alumina can block infrared rays, but its thermal conductivity is slightly smaller than that of mild steel, and its heat insulating property is not good.

By utilizing this characteristic, by inserting the insulating plate 22 made of alumina between the insulating plates 20 and 24,
The steep temperature gradient is relaxed to prevent the residual products of the material gas and the reaction gas from being generated and adhered, and also to prevent the insulating plates 20 and 24 from being damaged.

Insulating plate 18 surrounding the power supply plate 16
Is also made of quartz glass. This is to prevent the high frequency from leaking from the power supply plate 18 by enclosing the periphery of the power supply plate 16 with quartz glass having a good insulation property against the high frequency, and to reliably supply the high frequency to the installation plate 12 side. This is so that Although not shown, the power supply plate 16 and the insulating plate 18 are portions for performing pressure sealing between the vacuum chamber 2 and the outside, and are provided with a sealing material. In order to prevent the seal material from being damaged by heat, only the seal material portion is cooled, for example, water cooled, and the temperature is within the allowable temperature range of the seal material.

In this way, the insulating plates 20 and 2 made of quartz glass are used.
4 and the insulating plate 22 made of alumina are used, and the sealing material is water-cooled, so that the temperature at the base portion 4 is about 100 degrees Celsius.

In the above-mentioned structure, the space between the installation plate 12 and the power feeding plate 16 can be shortened by combining the insulating plates 20 and 24 having heat insulating properties and the normal insulating plate 22.
The length of the power supply tube 14 could be shortened. for that reason,
The power supply length is short and power loss can be reduced. However, when supplying high-frequency power to the installation plate 12, it is not possible to improve the power supply efficiency simply by shortening the length of the member for supplying power from the power supply plate 16 to the installation plate 12. This is because it is necessary to match the impedance due to the high frequency, and the high frequency current flows only on the surface of the member due to the high frequency skin effect. Therefore,
For feeding power from the power feeding plate 16 to the installation plate 12, a power feeding tube 14 having a hollow inside is used. Then, the surface area is increased in a possible range in consideration of the frequency of the high frequency and the electric power, and the volume and the cross-sectional area of the power feeding cylinder 14 are reduced in the strength allowable range to perform efficient power feeding. .

As described above, in this embodiment, by adopting the heat insulating structure in which the insulator having the high heat insulating property and the normal insulator are combined, the amount of heat conduction from the inside of the vacuum chamber 2 to the outside is increased. High frequency power is efficiently supplied by adopting a small size and a cylindrical power transmission unit.
Actually, a high frequency power source with a frequency of 13.56 and 27 MHz and an electric power of 500 W can be used to uniformly supply power to the large area processed object 8 and the formation of a sheath on the entire surface thereof is confirmed. 8 above 800 degrees C, plasma C
VD is possible for about 100 hours or more. At this time, the temperature of the base portion 4 was about 100 ° C.

In the above embodiment, the heat insulating structure has a three-layer structure of the high heat insulating insulator 20, the normal insulator 22 and the high heat insulating insulator 24. However, for example, the insulator 22 is continuous. It may be a plurality of layers or the insulators 20 and 22 may be a plurality of continuous layers. Further, in the above embodiment, high frequency power is used, but DC power can also be used. In that case, a solid rod-shaped body can be used instead of the hollow power supply cylinder 14. Further, although the ground electrode is provided in the vacuum chamber 2 in the above-described embodiment, the gas nozzle provided in the vacuum chamber 2 or the vacuum chamber itself may be used as the ground electrode.

[0030]

As described above, according to the present invention, by using an insulator containing an insulator having a high heat insulating property, the temperature distribution of the object to be treated can be made uniform and
The workability is good and the plasma CVD apparatus can be downsized. Moreover, when high frequency power is used, the power supply efficiency can be improved by using the power supply tube.

[Brief description of drawings]

FIG. 1 is a sectional view of a plasma CVD apparatus using an electrode according to an embodiment of the present invention.

[Explanation of symbols]

2 vacuum chamber 8 processed products 12 installation plates 14 power supply tube 16 power supply board 20 24 Insulation plate with high heat insulation 22 Insulation plate

Claims (4)

[Claims] 1. A flat plate-shaped power supply plate supported on a base, a conductive flat plate-shaped object placement plate disposed on the opposite side of the base from the power supply plate, and the power supply. The end surfaces contact one surface of the plate and the one surface of the processed product installation plate, and the area of these end surfaces is smaller than the area of the one surface of the power supply plate and the processed product installation plate and supplied from the power supply plate. An electric power transmission unit that transmits electric power to the treated product installation plate, and a periphery of the electric power transmission unit between the power supply plate and the processed product installation plate, which are laminated along a length direction of the electric power transmission unit. A plasma CV, comprising: a plurality of insulating plates, wherein the plurality of insulating plates include a material having a heat insulating property.
Electrode for D device. 2. The electrode for a plasma CVD device according to claim 1, wherein the insulating plate having the heat insulating property is arranged on each of the power supply plate side and the processed object installation plate side. 3. The electrode for a plasma CVD apparatus according to claim 2, wherein among the plurality of insulating plates, the insulating plate having the heat insulating property is quartz glass and the remaining insulating plates are alumina. electrode. 4. The electrode for a plasma CVD apparatus according to claim 1, wherein the electric power is high frequency electric power, and the power transmission unit is formed in a cylindrical shape.