JP3971288B2 - Carbon nanotube deposition system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a carbon nanotube film forming apparatus, and more particularly to a film forming apparatus using a microwave for forming a carbon nanotube thin film on a substrate to be processed made of a metal material. This carbon nanotube film forming apparatus is used as an apparatus for forming a film on a component that requires an electroluminescent element or the like as a substitute for a flat display (field emission display) or an electron tube of a CRT.
[0002]
[Prior art]
FIG. 1 shows a schematic configuration diagram for explaining the configuration of a conventional carbon nanotube film forming apparatus (Japanese Patent Application No. 2002-207906). The film forming chamber 1 that is a vacuum chamber is made of stainless steel and has a rectangular parallelepiped shape. In the film forming chamber 1, a door 1-a for taking out a sample substrate is attached to the side wall, and a water cooling pipe 1-b is wound around the film forming chamber. In the film forming chamber 1, a diaphragm vacuum gauge 1-c and an atmospheric pressure check device 1-d are attached.
[0003]
An upper flange 2 made of stainless steel is provided in the upper part of the film forming chamber 1, and a water-cooled pipe 1-b is wound around this flange as in the film forming chamber. A quartz window 2-a for introducing microwaves is attached to the upper flange 2 at the upper central portion of the flange. A cover glass 2-b is attached under the quartz window 2-a without opening a gap. A microwave system (microwave generator) 3, which is a three-dimensional circuit of a microwave oscillator and its waveguide, is attached to the upper flange 2, so that microwaves can be introduced into the film forming chamber 1. ing. The microwave generator 3 includes a cavity 3-a, a stub tuner 3-b, an incident / reflection detector 3-c, an isolator 3-d, and a microwave oscillator (hereinafter referred to as an “oscillator”). ) 3-e are connected via a rectangular waveguide in this order without a gap. As described above, the microwave output from the cavity 3-a of the microwave generator 3 is introduced into the film forming chamber 1 through the quartz window 2-a.
[0004]
A substrate stage system 4 is provided in the film forming chamber 1. As a sample substrate, for example, a Ni substrate 4-a having a diameter of about 10 cm and a thickness of 0.5 mm is configured to be mounted on a molybdenum substrate stage (hereinafter referred to as a stage) 4-b. Yes. This stage 4-b has a structure in which a place where the substrate on the upper surface is mounted is a drop structure, and the substrate 4-a can be mounted therein. Further, a hole having a diameter of about 8 cm is opened through the central portion of the cylinder of the substrate stage 4-b in the case of the substrate having the above dimensions. A quartz cover 4-c is provided below the stage 4-b, and a heater 4-d made of P-BN (Pyrotic Boron Nitride) and having a bowl shape is provided below the quartz cover 4-c. Yes. A current introduction rod 4-e is attached to the heater 4-d so that the power of the heater 4-d can be energized. Further, the thermocouple 4-f is fixed with a small space downward from the center of the surface of the heater 4-d. A heating power supply 4-g with a temperature adjusting function is connected to the current introduction rod 4-e via an introduction line 4-h taken out from the introduction rod to the atmosphere, and the thermocouple 4-f is energized. The sample substrate 4-a is heated and the temperature is kept constant.
[0005]
The film forming chamber 1 is also provided with a bias system 5. In this bias system, one end of the bias line 5-a is mechanically attached to the stage 4-b, and the other end of this bias line is the current introduction terminal 5 attached to the lower wall surface of the film forming chamber 1. It is connected to the DC power source 5-c via -b. This power supply 5-c has a power supply capacity of, for example, about 1 A, 500 V, its negative output terminal is connected to the bias line 5-a via a current introduction terminal, and the stage 4-b has a ground potential. On the other hand, a negative voltage is applied. On the other hand, the positive output terminal of the power source 5-c is grounded (earth). Although not shown, the film forming chamber 1 and the upper flange 2 are all grounded.
[0006]
Two kinds of gas introduction systems of gas introduction systems 6 and 7 are also connected to the film forming chamber 1. In order from the film formation chamber 1 side, in the case of the gas introduction system 6, the partition valve 6-a, the gas flow rate regulator 6-b, the partition valve 6-c, the pressure regulator 6-d, and the gas cylinder (hydrogen Gas cylinder) 6-e is connected, and in the case of the gas introduction system 7, a partition valve 7-a, a gas flow rate regulator 7-b, a partition valve 7-c, a pressure regulator 7-d, and a gas cylinder ( A methane gas cylinder) 7-e is connected. Although not shown in detail in the figure, these valves and devices are connected in a gas-tight manner with metal piping.
[0007]
Further, an exhaust system 8 is connected to the film forming chamber 1, and the gas flow rate adjusting valve 8-a, the partition valve 8-b, and the oil rotation are sequentially connected to the exhaust system from the film forming chamber side. A pump 8-c is connected. The film forming chamber 1 is provided with a pipe having a partition valve 8-d. These devices are also connected via airtight metal piping.
[0008]
The operation when using the conventional film forming apparatus will be described below.
In order to form a carbon nanotube by using this apparatus, first, the valves 8-b, 8-a and 8-d are opened, and the oil rotary pump 8-c is operated to operate in the film forming chamber 1. Is evacuated. In this state, the pressure in the film forming chamber 1 is measured by the diaphragm vacuum gauge 1-c. The pressure in the deposition chamber 1 is -10 ^-2 When the pressure reaches about Torr, the gate valve 8-d is closed. And electric power is output from the heating power supply 4-g, and the heater 4-d is heated. When the thermocouple 4-f reaches about 450 ° C., the temperature is kept constant. Next, the main plug of the hydrogen gas cylinder 6-e is opened, and the partition valves 6-c and 6-a are also opened, and 80 sccm of hydrogen gas is introduced into the film forming chamber 1 through the gas flow rate regulator 6-b. Further, the gas flow rate adjusting valve 8-a is adjusted to set the pressure in the film forming chamber 1 to 2 Torr. Then, 500 W of microwaves are input from the microwave generator 3. At this time, the tuner 3-b is adjusted while observing the incident / reflection detector 3-c so that the amount of the reflected wave is reduced. As a result, plasma is turned on in the film forming chamber 1.
[0009]
Next, the bias power source 5-c is output. Set to constant voltage mode (the voltage can be changed arbitrarily, the current varies according to the load), and -250V is output. A current of about 60 mA to 80 mA flows through the sample substrate 4-a. This state is continued for 15 minutes to clean the surface of the substrate 4-a.
[0010]
After the cleaning is completed, the main plug of the methane gas cylinder 7-e is opened, the partition valves 7-c and 7-a are opened, and the gas flow rate regulator 7-b is set to 40 sccm. On the other hand, the gas flow rate adjuster 6-b for hydrogen gas is adjusted to 60 sccm. Next, methane gas 40 sccm and hydrogen gas 60 sccm are simultaneously introduced into the film formation chamber 1. Further, the gas flow rate adjusting valve 8-a is adjusted to set the pressure in the film forming chamber 1 to 3 Torr. Thereafter, 1500 W of microwaves is input from the microwave generator 3. At this time, the tuner 3-b is adjusted while observing the incident / reflection detector 3-c so that the amount of the reflected wave is reduced. A bias voltage of −400 V is applied. At this time, when a voltage is applied, a current of about 360 mA to 400 mA flows, and when 1 minute elapses, the current value decreases to 200 mA, and after 5 minutes it becomes 80 mA to 100 mA. Although the film formation time is set according to the length (film thickness) of the carbon nanotube, the film is formed normally for about 5 to 30 minutes.
[0011]
Next, the microwave from the microwave generator 3 and the output of the bias power source 5-c are stopped, the valves of the gas introduction systems 6 and 7 are closed, and the gas supply is stopped. Thereafter, the output of the heating power source 4-g is stopped, the partition valve 8-b is closed, and the sample substrate 4-a is waited until it is cooled to near room temperature. When the temperature returns to room temperature, although not shown, nitrogen gas is introduced into the film forming chamber 1 and when the atmospheric pressure check device 1-d is turned on, the sample door 1-a is opened and the sample substrate 4-a is taken out.
[0012]
[Problems to be solved by the invention]
In the conventional carbon nanotube film forming apparatus shown in FIG. 1, since the film forming chamber 1 and the upper flange 2 are cooled, when methane gas is generated, the methane gas is decomposed in the plasma and chemically activated. New molecules are obtained. The molecules are adsorbed on the inner wall of the film forming chamber 1 and the surface of the inner wall of the upper flange 2 to form an organic thin film. This organic thin film is generally electrically insulating, and when plasma is generated, electrons in the plasma adhere to and accumulate on the surface of the organic thin film. When electrons accumulate in the organic thin film, they are charged up, and when they accumulate and increase in quantity, a strong electric field is generated. As a result, the organic thin film eventually ruptures and causes arcing between the upper flange 2 and the substrate stage 4-b. This arcing causes a disadvantage that the carbon nanotubes grown on the substrate 4-a are blown away.
[0013]
Further, when the electrons adhere to the organic thin film formed on the inner wall surface of the upper flange 2, the potential of the inner surface of the upper flange 2 is lowered from the ground potential. For this reason, the potential difference from the negative bias voltage applied to the stage 4-b is reduced, and the effective potential difference applied to the stage is reduced. Thus, the volume of the sheath formed around the stage 4-b exposed to the plasma is reduced, and the ion current value flowing into the stage is reduced. When the ionic current value becomes small, the current value of the lower limit for forming the carbon nanotube film may be lowered, which causes a problem that a good quality carbon nanotube film cannot be formed.
[0014]
Furthermore, in the conventional film forming apparatus, since the microwave introduction window 2-a and the substrate 4-a are separated from each other, the plasma is diffused, and the high-density plasma cannot be held on the substrate. There is also a problem that a long (thick film) carbon nanotube film cannot be grown in a short time.
An object of the present invention is to solve the above-mentioned problems of the prior art, and remarkably reduce the charge-up and increase the current value of ions flowing into the stage to form a high-quality carbon nanotube film. An object of the present invention is to provide a carbon nanotube film forming apparatus that can perform the above process.
[0015]
[Means for Solving the Problems]
The carbon nanotube film forming apparatus of the present invention includes a film forming chamber, a substrate stage that is provided in the film forming chamber and is electrically insulated from a ground potential, and is opposed to the film forming chamber. A microwave generator using a cavity coaxially converted from a rectangular waveguide, and a dielectric for introducing the microwave generated by the microwave generator into the film forming chamber In a plasma CVD apparatus that separates air and vacuum using a window, a quartz cylinder on the substrate stage The quartz cylinder is closely attached between the substrate stage and the upper flange of the film forming chamber, and a quartz disk is mounted in the opening of the upper flange above the quartz cylinder. The outer diameter of the quartz disk is 0.5 to 2.0 mm smaller than the inner diameter of the opening of the upper flange of the film forming chamber, and the quartz disk is a window for introducing microwaves. It is installed so that the gap with the cover glass provided in contact with is kept within 1.0 mm It is characterized by that.
[0016]
the above In the film forming apparatus, it is preferable to provide a reverse bias mechanism that can apply a negative voltage with a direct current to the substrate stage and periodically apply a positive voltage superimposed on the negative voltage. .
[0017]
Ma The film forming chamber is provided with means capable of supplying high-frequency power, and the high-frequency output is half-wave rectification or rectangular-wave output.
The frequency of the high frequency is preferably 2.45 GHz or more. If it is less than 2.45 GHz, the plasma density required for growing carbon nanotubes cannot be obtained.
[0018]
According to the film forming apparatus of the present invention, since the quartz cylinder is installed in close contact between the substrate stage and the inner wall of the upper flange (upper electrode), and since the quartz disk is mounted, this apparatus Is used to form a high-quality carbon nanotube film with a small thickness and a long thickness on a sample substrate in a short time.
[0019]
In addition, according to another film forming apparatus of the present invention, by attaching a reverse bias mechanism such as an inverter power supply instead of a DC power supply as a power supply to be applied to the substrate stage, the current flowing into the substrate is further increased. As the growth rate increases, the charge-up by electrons is mitigated and arcing is greatly reduced. The inverter power supply is a power supply of bipolar (plus / minus output is possible) output, and is a power supply capable of applying an output voltage in accordance with the frequency and the pulse width. By using such an inverter power supply or the like, plus and minus outputs can be alternately applied to the substrate stage when the carbon nanotube is formed. Therefore, when a plus is output, a film forming process is performed. When a minus is applied, the film is attached to the inner wall of the upper electrode, and the charged-up electrons are peeled off to ease the charge-up. .
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of a carbon nanotube film forming apparatus according to the present invention will be described below.
The basic configuration of the carbon nanotube film forming apparatus of the present invention is almost the same as that of the conventional carbon nanotube film forming apparatus shown in FIG. I can understand it, so I will omit it. Hereinafter, the configuration and operation of the power supply used, including the quartz cylinder and the quartz disk, which are the differences between the two, will be described.
FIG. 2 shows a schematic cross-sectional view of the configuration between this stage and the microwave introduction window when a quartz cylinder or quartz disk is mounted on the substrate stage. 2, the same components as those in FIG. 1 are denoted by the same reference numerals.
[0021]
As shown in FIG. 2, the quartz stage (quartz cylinder) 9-a is closely mounted between the substrate stage 4-b and the upper flange 2. The quartz stage 9-a has a cylindrical shape. The inner diameter of the quartz stage 9-a is preferably smaller than the outer diameter and about 95 mm when the outer diameter of the sample substrate 4-a is, for example, φ100 mm. Further, the quartz disk is installed between the quartz cylinder 9-a and the quartz window 2-a, and the number of quartz disks is not limited as long as the intended purpose can be achieved. (9-b and 9-c) are shown superimposed. The quartz disks 9-b and 9-c are manufactured to have an outer diameter that is 1.0 mm to 2.0 mm smaller than the diameter φID of the microwave inlet (opening) of the upper flange 2. The two quartz disks 9-b and 9-c have a vertical distance (H) from the surface of the cover glass 2-b on the film forming chamber side to the surface of the quartz cylinder on the cover glass side. ) To be 0.5 to 1.0 mm shorter than that and set at a predetermined position.
[0022]
As described above, the process for forming a carbon nanotube using the carbon nanotube film forming apparatus provided with the quartz cylinder 9-a and the quartz disks 9-b and 9-c is the same as the process described with reference to FIG. To implement.
As described above, since the quartz cylinder 9-a is placed in close contact between the stage 4-b and the inner wall of the upper flange 2, there is no space between the stage and the inner wall of the upper flange. ) Is less likely to occur. In addition, by mounting the quartz disks 9-b and 9-c at predetermined positions, the sample substrate 4-a can be used against a discharge in which the side surface of the opening portion of the microwave introduction portion of the upper flange 2 is an arc generation source. However, even if arcing is generated from the above place, arc (lightning) does not fall on the sample substrate and damage to the carbon nanotubes is reduced.
[0023]
Further, since the quartz disks 9-b and 9-c are arranged so as to overlap the quartz cylinder 9-a, the microwave is emitted from the lower surface of the lower quartz disk 9-c, and the plasma is ignited. As a result, the plasma is positioned close to the sample substrate 4-a. Further, since the plasma is ignited inside the quartz cylinder 9-a, the plasma is confined within a certain region, and thus the plasma density is increased. From this, it is possible to form a thick (long) carbon nanotube film with few discharge traces on the sample substrate 4-a in a short time.
[0024]
Next, a carbon nanotube film forming apparatus according to another embodiment of the present invention will be described with reference to FIG.
FIG. 3 is a schematic diagram for explaining the configuration of an inverter power supply 10 that can be used in the carbon nanotube film forming apparatus of the present invention instead of the DC power supply 5-c of the bias system 5 in the film forming apparatus of FIG. A block diagram is shown.
[0025]
According to the conceptual diagram of the inverter power source 10 shown in FIG. 3, one DC power source having a positive output and one negative output is shown. That is, a negative output DC power supply 10-a and a positive output DC power supply 10-b are provided. A switching circuit 10-c is provided on the output side, and is configured to be able to switch between a positive output and a negative output. In the case of the positive output power source 10-b, the negative side is grounded, and in the case of the negative output power source 10-a, the positive side is grounded. As in the case of the film forming apparatus shown in FIG. 1, the output side is connected to the stage 4-b via the current introduction terminal 5-b by the bias line 5-a of the bias system 5, and through the bias line 5-a. A voltage is applied to the stage 4-b.
[0026]
When the carbon nanotube is formed, the minus voltage is set to −400 V and the plus voltage is set to +80 V as the output of the inverter power supply 10. The pulse width for producing a positive voltage is 5 μs, and the frequency is 20 kHz. Carbon nanotubes are formed in this way. Since the film forming procedure and parameters are the same as those in the film forming process using the film forming apparatus shown in FIG. 1 until the cleaning step, the film forming process after the cleaning is completed will be described below.
[0027]
The main plug of the methane gas cylinder 7-e is opened, the partition valves 7-c and 7-a are opened, and the gas flow rate regulator 7-b is set to 40 sccm, for example. On the other hand, the main plug of the hydrogen gas cylinder 6-e is opened, the partition valves 6-c and 6-a are opened, and the gas flow rate regulator 6-b is set to 60 sccm, for example. Next, methane gas 40 sccm and hydrogen gas 60 sccm are simultaneously introduced into the film forming chamber 1. Further, the valve 8-a is adjusted to set the pressure in the film forming chamber 1 to 3 Torr. Thereafter, 1500 W of microwaves is input from the microwave generator 3. At this time, the tuner 3-b is adjusted while observing the incident / reflection detector 3-c so that the amount of the reflected wave is reduced. Next, a bias voltage from the inverter power supply 9 is applied in accordance with the set voltage, frequency, and pulse width, and carbon nanotube film formation is started. The current at this time flows from about 600 mA to 400 mA when a voltage is applied, and the current value decreases to 400 mA after 1 minute, and decreases to 360 mA to 320 mA after 10 minutes. The film formation time is set according to the length of the carbon nanotubes. By default, when the film is formed for about 5 to 30 minutes, the carbon nanotubes are stably formed in the range of about φ6 cm at the center of the substrate. Since the stop of the apparatus and the removal of the substrate after the film formation are the same as those described for the apparatus of FIG. 1, the description thereof is omitted.
[0028]
In the above embodiment, the case where an inverter power source is used as the power source has been described. The reverse bias mechanism used in the present invention is not limited to this inverter power supply, and is not limited as long as it can output reverse polarity and can operate at a frequency of about several tens of kHz in terms of time. For example, the intended purpose of the present invention can be achieved by using a commercially available abnormal discharge prevention unit.
[0029]
Hereinafter, the principle of the carbon nanotube film forming apparatus of the present invention will be described. FIG. 4 shows a schematic diagram of the inside of the film forming chamber 1 during the carbon nanotube film forming performed using the conventional film forming apparatus (FIG. 1). Reference numerals of elements in FIG. 4 and FIGS. 5 to 6 described below correspond to the case in FIG. When the carbon nanotube is formed, a microwave is introduced from the quartz window 2-a and the plasma is ignited. Then, the electrically insulating organic thin film 11 adheres to the inner wall of the upper flange.
[0030]
FIG. 5 is a schematic diagram showing the inside of the film forming chamber 1 when the plasma is ignited in a conventional film forming apparatus using the DC power source 5-c. A broken line in the drawing represents a plasma sheath formed when a bias voltage is applied on the stage 4-b. In the bias of the DC voltage from the DC power source 5-c, electrons in the plasma are adsorbed on the organic thin film 11 having a low potential because a large negative voltage (−400 V) is applied to the stage 4-b. Is done. When electrons start to be adsorbed, the electrons gradually accumulate on the organic thin film 11, and as a result, charge-up occurs. When the electric field generated by the accumulated electrons exceeds the breakdown electric field, it bursts. That is, abnormal discharge occurs between the stage 4-b and the upper flange.
[0031]
FIG. 6 shows a schematic diagram of the inside of the film forming chamber 1 when the plasma is ignited in the film forming apparatus of the present invention using the inverter power supply 10. A broken line in the drawing represents a plasma sheath formed when a bias voltage is applied on the stage 4-b. FIG. 7 shows the time change of the voltage waveform of the inverter power supply. In FIG. 7, for example, Δt is 5 μs, VB is −400 V, Vs is +80 V, and f is a frequency of 20 kHz. When output using the inverter power supply, the electrons accumulated on the organic thin film 11 are applied with +80 V to the stage 4-b in 5 μs, so that they are separated from the organic thin film toward this stage. On the other hand, although a positive voltage is applied to the stage 4-b on the ions in the sheath, since the mass is heavier than that of the electrons, the ions in the sheath do not move much due to inertia. When the polarity changes, the ions receive a negative electric field and collide with the stage 4-b. In fact, at 20 kHz, the time during which ions are accelerated is 0.5 ms, and this time is sufficient as the time during which ions are accelerated by feeling a negative electric field. On the other hand, electrons adhere and accumulate on the organic thin film 11.
[0032]
Since electrons repeat the above attachment and detachment, the accumulation of electrons only reaches a certain limit. However, when the inverter power supply 10 is used, the charge-up is further eased compared to the case where the DC power supply 5-c is used. . Further, since the amount of electrons accumulated on the organic thin film 11 is small, the negative potential is naturally close to the ground potential, so that the effective potential difference between the stage 4-b and the upper flange 2 is increased, and ions are generated. Since the electric field that looks into the stage also increases, the width of the plasma sheath also increases. That is, the volume increases and the current value of ions flowing into the stage increases.
[0033]
【Example】
In the following examples, carbon nanotubes were formed under the following cleaning conditions and film formation conditions using the film formation apparatus of FIG. 1 having the elements shown in FIGS. 2 and 3 according to the conventional film formation process described above. .
Example 1
Cleaning conditions:
(1) Substrate temperature: 350 ° C
(2) Microwave power: 0.5kW
(3) Pressure during film formation: about 2 Torr
(4) Gas type: Hydrogen
(5) Substrate bias: -250V, current value: 60mA
▲ 6 ▼ Cleaning time: 15 minutes
[0034]
Deposition conditions:
(1) Sample substrate: φ100 mm Ni substrate (thickness: 0.5 mm)
(2) Substrate temperature: 350 ° C
(3) Microwave power: 1.5kW
(4) Pressure during film formation: about 3 Torr
(5) Gas type: hydrogen, methane
(6) Substrate bias: -440V, current value: 100mA
(7) Distance from the quartz window to the sample substrate: approx. 40 mm
(8) Distance from the lower surface of the lower quartz disk to the sample substrate: about 17 mm
(9) Deposition time: 15 minutes
[0035]
By forming the film under the above conditions, carbon nanotubes were stably formed in the range of about 3 to 6 cm in the center of the substrate. FIG. 8 shows an SEM photograph of carbon nanotubes formed under these conditions. As is clear from FIG. 8, the obtained carbon nanotube film was thick (long) and sufficiently durable for practical use, and there was no discharge trace on the surface.
[0036]
(Example 2)
In the first embodiment, a DC voltage is used as the voltage applied to the substrate. However, the present invention is not limited to the DC voltage, and the carbon nanotube can be formed even with a pulsed voltage to which a reverse bias voltage can be applied. Then, it describes about the case where the reverse pulse voltage of the following conditions is superimposed on DC voltage. As a result, it was possible to form good carbon nanotubes by increasing the film formation rate.
[0037]
Cleaning conditions:
(1) Substrate temperature: 350 ° C
(2) Microwave power: 0.5kW
(3) Pressure during film formation: about 2 Torr
(4) Gas type: Hydrogen
(5) Substrate bias: -250V, current value: 160mA
▲ 6 ▼ Cleaning time: 15 minutes
[0038]
Reverse pulse voltage condition:
(1) Output voltage: + 80V
(2) Pulse shape: rectangular wave
(3) Frequency: 20kHz
(4) Pulse width: 5μs
[0039]
Deposition conditions:
(1) Sample substrate: φ100 mm Ni substrate (thickness: 0.5 mm)
(2) Substrate temperature: 350 ° C
(3) Microwave power: 1.5kW
(4) Pressure during film formation: about 3 Torr
(5) Gas type: hydrogen, methane
(6) Substrate bias: -440V, current value: 300mA
(7) Distance from the quartz window to the sample substrate: approx. 40 mm
(8) Distance from the lower surface of the lower quartz disk to the sample substrate: about 17 mm
(9) Deposition time: 30 minutes
[0040]
By forming the film under the above conditions, as can be seen from the parameters, the current flowing into the sample substrate is increased by 2 to 3 times when the reverse bias is superimposed and applied as compared with the case of Example 1. I understand that. From this, it can be seen that the amount of carbon supply increases and the growth rate of carbon nanotubes increases. Moreover, arcing was greatly reduced by reducing the charge-up by electrons at the upper electrode. Conventionally, arcing occurred 2 to 3 times in 30 minutes of film formation, but no longer occurred once by applying a reverse pulse voltage in a superimposed manner.
[0041]
【The invention's effect】
According to the present invention, since the quartz cylinder is installed in close contact between the substrate stage and the inner wall of the upper flange, there is no space between the substrate stage and the inner wall of the upper flange, so that discharge (arcing) is unlikely to occur. Become. In addition, by mounting a quartz disk at a predetermined position, the sample substrate cannot be expected to have a substantially three-dimensional angle with respect to a discharge in which the side surface of the opening portion of the microwave introduction portion of the upper flange is an arc generation source. Therefore, even if arcing starting from the above-mentioned place occurs, an arc (lightning) does not fall on the sample substrate, and damage to the carbon nanotube is reduced.
[0042]
Further, by arranging the quartz disk so as to overlap the quartz cylinder, the microwave is emitted from the lower surface of the quartz disk, and the plasma is ignited. This brings the plasma closer to the sample substrate. Furthermore, since the plasma is ignited inside the quartz cylinder, the plasma is confined within a certain region, and thus the plasma density is increased. From this, it becomes possible to form a thick (long) carbon nanotube film with few discharge traces on the sample substrate in a short time.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing the configuration of a conventional carbon nanotube film forming apparatus.
FIG. 2 is a schematic cross-sectional view showing a configuration around a quartz stage in the carbon nanotube film forming apparatus of the present invention.
FIG. 3 is a schematic diagram showing a configuration example for explaining an inverter power source used in the carbon nanotube film forming apparatus of the present invention.
FIG. 4 is a schematic view showing a configuration of a film forming chamber during film formation in a conventional carbon nanotube film forming apparatus.
FIG. 5 is a schematic diagram showing the behavior of electrons and ions in a film forming chamber in a conventional carbon nanotube film forming apparatus.
FIG. 6 is a schematic diagram showing the behavior of electrons and ions in a film forming chamber in the carbon nanotube forming apparatus of the present invention using an inverter power supply.
FIG. 7 is a diagram showing a time change of a voltage waveform applied from an inverter power supply on the substrate stage in FIG. 6;
8 is a SEM photograph of a carbon nanotube film formed according to Example 1. FIG.
[Explanation of symbols]
1 Deposition chamber 2 Upper flange
2-a Quartz window 3 Microwave generator
4 Substrate stage system 4-a Substrate
4-b Substrate stage 5 Bias system
5-c DC power supply 6, 7 Gas introduction system
8 Exhaust system 9-a Quartz cylinder
9-b, 9-c Quartz disc 10 Inverter power supply
11 Organic thin film

Claims (4)

A film forming chamber, a substrate stage provided with a substrate to be processed, which is electrically insulated from a ground potential, and a rectangular waveguide provided facing the film forming chamber. And a microwave generator using a cavity converted from the same axis from the atmosphere, and using a window made of a dielectric for introducing the microwave generated by the microwave generator into the film formation chamber, the atmosphere and vacuum are In the isolated plasma CVD apparatus, a quartz cylinder is mounted on the substrate stage, and the quartz cylinder is closely attached between the substrate stage and the upper flange of the film forming chamber, the quartz cylinder A quartz disk mounted in the opening of the upper flange above the upper flange, the outer diameter of the quartz disk being 0.5 to 2.0 mm smaller than the inner diameter of the opening of the upper flange, and Quartz disc introduces microwave Carbon nanotube film forming apparatus, wherein a gap is provided so as to be held within 1.0mm of the cover glass provided in contact with the window for. 2. A reverse bias mechanism capable of applying a negative voltage with a direct current to the substrate stage and periodically applying a positive voltage superimposed on the negative voltage. Carbon nanotube film forming equipment. 3. The carbon nanotube film forming apparatus according to claim 1 , further comprising means capable of supplying high frequency power to the film forming chamber, wherein the high frequency output is half-wave rectification or rectangular wave output . 4. The carbon nanotube film forming apparatus according to claim 3 , wherein the frequency of the high frequency is 2.45 GHz or more .

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