JP2005072345A - Device and method for plasma treatment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device and method for plasma treatment by which plasma of a higher density can be obtained in a state where the rise of manufacturing cost or the occurrence of damages is suppressed. <P>SOLUTION: The device is provided with a lower electrode 102 on which a substrate W to be treated is placed and an upper electrode 103 which is disposed to face the lower electrode 102 in a hermetically sealable treatment chamber 101. The lower and upper electrodes 102 and 103 are fixed in the chamber 101 in insulated and separated states. High-frequency power can be supplied across the electrodes 103 and 102 from a high-frequency power source 106. In addition, a field emission type electron supplying source 110 constituted of, for example, a plurality of carbon nanotubes is provided on the surface facing the lower electrode 102 of the upper electrode 103 which becomes an anode. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a plasma processing apparatus and a plasma processing method capable of generating high density plasma.

  In the manufacture of semiconductor devices and flat panel displays, various plasmas such as parallel plate plasma processing devices and inductively coupled plasma processing devices are used to perform oxide film formation, semiconductor layer crystal growth, etching, and ashing. A processing device is used. As an example, a parallel plate plasma processing apparatus will be described. There is a plasma apparatus as shown in FIG. 7 (see Patent Documents 1, 2, 3, and 4).

  The outline of this apparatus will be briefly described. Inside the sealable processing chamber 701, a lower electrode 702 on which a substrate W to be processed is placed and an upper electrode 703 arranged to face the lower electrode 702 are provided. For example, first, the inside of the processing chamber 701 is evacuated by an exhaust device (not shown) communicating with the exhaust port 704, and a predetermined gas is introduced from the gas introduction port 705 to set the inside of the processing chamber 701 to a predetermined pressure. In this state, high-frequency power is supplied from the high-frequency power source 706 to the lower electrode 702 via the matching unit 707, so that plasma of the gas can be generated between the lower electrode 702 and the upper electrode 703.

The applicant has not yet found prior art documents related to the present invention by the time of filing other than the prior art documents specified by the prior art document information described in this specification.
Japanese Patent Laid-Open No. 06-068839 Japanese Patent Application Laid-Open No. 07-074115 Japanese Patent Laid-Open No. 08-148295 JP 2001-156051 A

  In the plasma processing apparatus as described above, it is an important technical problem to improve the processing speed, and one of them is to increase the plasma density. In order to increase the plasma density without changing the configuration of the apparatus, for example, it is conceivable to increase the power of the high-frequency power or increase the gas supply amount. However, these cause an increase in manufacturing cost. Further, when the high frequency power is increased, for example, the incident energy of ions generated from plasma and acting on the substrate to be processed is increased, and damage to the substrate may become a problem.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to obtain a plasma with a higher density while suppressing an increase in manufacturing cost and occurrence of damage. And

The plasma processing apparatus of the present invention is a plasma processing apparatus that generates plasma in a processing container and performs a predetermined processing by the action of the generated plasma, and includes a field emission type electron supply source disposed in the processing container. It is a thing.
In this apparatus, electrons are supplied from an electron supply source into the generated plasma.

  The plasma processing apparatus includes an anode electrode serving as an anode disposed in a processing container, a cathode electrode disposed opposite to the anode electrode, and a power supply unit that supplies power between the anode electrode and the cathode electrode, An exhaust unit that exhausts the inside of the processing container to reduce the pressure to a predetermined pressure and a gas introduction unit that introduces a desired gas into the processing container are provided.

  In the plasma processing apparatus, the electron supply source only needs to be composed of a plurality of carbon nanostructures provided on the surface of the anode electrode facing the cathode electrode. Further, the electron supply source may be an electrode structure that is disposed in a region surrounding a space between the anode electrode and the cathode electrode, and a plurality of carbon nanostructures are provided on a surface facing the space. In this case, the carbon nanostructure may be a carbon nanotube. Carbon nanohorns and carbon nanowalls may also be used.

The plasma processing method of the present invention also includes an anode electrode serving as an anode disposed in a processing container, a cathode electrode disposed opposite to the anode electrode, and power for supplying power between the anode electrode and the cathode electrode. At least a supply means, an exhaust means for exhausting the inside of the processing container to reduce the pressure to a predetermined pressure, and a gas introduction part for introducing a desired gas into the processing container, and generating plasma in the processing container A plasma processing method using a plasma processing apparatus that performs a predetermined process by the action of the plasma that has been generated, in which a carbon source gas is introduced into a processing vessel from a gas introduction unit while the anode electrode is heated, whereby an anode A first step of growing carbon nanotubes by a chemical vapor deposition method on a surface of the electrode facing the cathode electrode; In a state where the pressure is reduced to a predetermined pressure, a predetermined gas is introduced into the processing vessel from the gas introduction unit, power is supplied to the anode electrode and the cathode electrode by the power supply means, and a predetermined amount is provided between the anode electrode and the cathode electrode. And a second step of generating a plasma of the gas.
According to this method, electrons are supplied from the electron supply source into the generated plasma.

  According to the present invention, since the electron supply source is provided in the processing container, for example, low energy electrons can be supplied into the plasma. As a result, according to the present invention, it is possible to generate plasma with a higher density without increasing the amount of gas to be supplied and without increasing the power to be supplied. As described above, according to the present invention, it is possible to obtain an excellent effect that a plasma having a higher density can be obtained in a state where an increase in manufacturing cost and generation of damage are suppressed.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a schematic configuration example of a plasma processing apparatus in an embodiment of the present invention. In this plasma processing apparatus, first, in a sealable processing chamber 101, a lower electrode (cathode electrode) 102 on which a substrate W to be processed is placed, and an upper electrode (anode electrode) disposed to face the lower electrode 102 are disposed. 103. The lower electrode 102 and the upper electrode 103 are fixed in a state where they are insulated and separated inside the processing chamber 101. Note that the vertical relationship between the lower electrode 102 and the upper electrode 103 is the same even if they are interchanged.

  The inside of the processing chamber 101 can be decompressed by an exhaust device (not shown) communicating with the exhaust port 104. A predetermined gas can be introduced into the processing chamber 101 through a gas inlet 105. For example, a desired gas can be supplied into the processing chamber 101 by connecting a pipe provided with a mass flow controller, a valve, or the like to the gas introduction port 105 and connecting a gas cylinder or the like in which the desired gas is stored.

Further, high frequency power can be supplied from the high frequency power source 106 between the upper electrode 103 and the lower electrode 102. The high frequency power output from the high frequency power source 106 is supplied to the lower electrode 102 via the matching unit 107. The upper electrode 103 is connected to the ground potential. The processing chamber 101 may be connected to a ground potential.
In addition, the plasma processing apparatus of the present embodiment includes a field emission type electron supply source 110 made of, for example, a plurality of carbon nanotubes on the surface of the upper electrode 103 serving as an anode facing the lower electrode 102.

  An example of the operation of the plasma processing apparatus of the present embodiment shown in FIG. Gas is introduced, and the inside of the processing chamber 101 is set to a predetermined pressure. In this state, high-frequency power (13.56 to 100 MHz) is supplied from the high-frequency power source 106 to the lower electrode 102 via the matching unit 107, thereby generating plasma using the gas in the processing chamber 101.

  At this time, an electric field is formed between the carbon nanotubes constituting the electron supply source 110 provided in the upper electrode 103 and the generated plasma. As a result, for example, a high electric field concentrates on the tip portion of the carbon nanotube, and as a result, electrons are emitted from the tip portion, and the emitted electrons are supplied into the plasma. Further, the supplied electrons have lower energy than electrons generated by plasma.

  As a result, in the plasma generated in the space between the upper electrode 103 and the lower electrode 102, more electrons are supplied and the plasma density is high. According to the plasma generation apparatus of the present embodiment, even when the gas supply amount and the high-frequency power supply amount are the same, the plasma density is increased by one digit or more compared to the case where the electron supply source 110 is not provided. Is possible. In addition, since the supplied electrons are in a low energy state, damage to the substrate to be processed is not increased.

Incidentally, in the plasma generating apparatus of FIG. 1, the upper electrode 103 is connected to the ground potential, but the present invention is not limited to this.
FIG. 2 is a block diagram showing a schematic configuration example of a plasma generating apparatus according to another embodiment of the present invention. In this apparatus, a high frequency power source 201 is connected to the upper electrode 103 via a matching unit 202, and high frequency power (13.56 to 100 MHz) is supplied to the upper electrode 103. For example, by supplying high-frequency power having a frequency different from that of the lower electrode 102 to the upper electrode 103, the upper electrode 103 can operate stably, and a pseudo DC bias can be applied to the upper electrode 103.

  For example, when the frequency of the electric power supplied from the high frequency power supply 201 is changed, the electric field strength between the generated plasma and the upper electrode 103 can be controlled. By controlling the electric field strength, the energy of electrons emitted from the electron supply source 110 can be controlled. In addition, by making the high frequency power supplied to the upper electrode 103 and the lower electrode 102 different, the amount of electrons emitted from the electron supply source 110 can be controlled. In FIG. 2, the same components as those in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted.

  Further, as shown in FIG. 3, a power supply 301 for supplying low frequency power of about 400 kHz is added, and the high frequency power supply 201 and the power supply 301 are connected in parallel by an interference suppression circuit 303. The power from 301 may be supplied via the matching unit 302. In FIG. 3, the same components as those in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted.

  Further, as shown in FIG. 4, an electrode structure 411 newly connected to the ground potential is provided on the side of the space sandwiched between the lower electrode 102 and the upper electrode 103 disposed so as to face each other. You may make it provide the electron supply source 410 which consists of a some carbon nanotube in the surface which goes to the plasma of the structure 411, for example. The electrode structure 411 may be a side surface of the processing chamber 101. At this time, the processing chamber 101 is connected to the ground potential. In FIG. 4, the same components as those in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted.

  As shown in FIG. 4, by adding the electron supply source 410 of the side electrode structure 411 in addition to the electron supply source 110 of the upper electrode 103, a higher electron supply effect can be obtained. In the configuration shown in FIG. 4, the electron supply source 410 may be provided only on the side electrode structure 411 without providing the electron supply source on the surface of the upper electrode 103 facing the lower electrode 102. Needless to say.

Next, formation of carbon nanotubes used as an electron supply source will be described.
The carbon nanotube is a completely graphitized cylindrical object having a diameter of about 4 to 50 nm and a length of about 1 to 10 μm. Carbon nanotubes having such a shape include a single-layer structure and a coaxial multilayer structure in which a plurality of layers are stacked. These cylindrical central portions are hollow. In addition, there is a tip portion that is closed or a tip portion that is opened by being broken.

Carbon nanotubes having such a unique shape can be used as an electron emission source. Carbon nanotubes have physical properties suitable as a field emission source, such as the sharp radius of curvature at the tip, on the order of nm, and being chemically stable and mechanically tough.
Carbon nanotubes having such characteristics can be formed, for example, by growing them on a substrate on which a catalytic metal such as nickel or cobalt is present by a chemical vapor deposition (CVD) method using a carbon source gas ( Document: JP 2001-048512 A).

For example, a substrate made of stainless steel such as 426 alloy is prepared as an upper electrode, and this is placed inside a reaction furnace composed of, for example, a quartz tube, and a carbon source gas and a hydrogen gas (carrier) are supplied from one of the reaction furnaces. The substrate is heated to 600 to 900 ° C. in a state of flowing gas. In this chemical vapor deposition process, carbon monoxide gas may be used as the carbon source gas, and the flow rate may be about 500 sccm. The carrier gas flow rate may be 1000 sccm.
As a result, a state in which a plurality of carbon nanotubes are formed on the surface of the substrate can be obtained.

It is also possible to use C _x H _y (x = 1 to 3) hydrocarbon gas such as acetylene, ethylene, ethane, propylene, propane, or methane gas as the carbon source gas. The substrate is not limited to stainless steel, and the surface of the substrate on which carbon nanotubes are to be formed only needs to be made of a material containing a metal (catalytic metal) on which carbon nanotubes grow by chemical vapor deposition. . This metal may be any of iron, nickel, cobalt, chromium, or an alloy thereof.

  In general, aluminum or an alloy thereof, SiX or a carbon graphite plate is often used for the upper electrode. In such a case, a fine pattern of a plurality of catalytic metals may be prepared on the surface of the upper electrode made of aluminum, and these carbon nanotubes may be grown. For example, first, as shown in FIG. 5A, a plurality of catalyst metal patterns 502 are formed on the surface of the aluminum substrate 501 at predetermined intervals. The catalytic metal pattern 502 can be formed, for example, by forming a catalytic metal film and then processing it by a known photolithography technique and etching technique.

  Next, the aluminum substrate 501 is placed in the above-described reaction furnace, and the aluminum substrate 501 is heated to a predetermined temperature in a state where a carbon source gas and a carrier gas are flowed from one of the reaction furnaces. As a result, as shown in FIG. 5B, carbon nanotubes 503 grow on each catalytic metal pattern 502. Thus, the upper electrode 103 of the plasma processing apparatus shown in FIG. 1 can be formed by using an aluminum substrate on which carbon nanotubes are formed.

  Incidentally, carbon nanotubes may be formed by introducing a carbon source gas into the plasma processing apparatus into the upper electrode incorporated in the plasma processing apparatus. For example, as shown in FIG. 6, an electron supply source 110 made of carbon nanotubes can be formed on the opposing surface of the upper electrode 103 by incorporating a heater 601 in the upper electrode 103 so that the upper electrode 103 can be heated. It becomes possible. Here, it is assumed that the upper electrode 103 is made of, for example, SUS (stainless steel). In FIG. 6, the same components as those in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted.

  The formation of the electron supply source 110 will be described. First, the carbon source gas described above is introduced together with the carrier gas from the gas introduction port 105, and the upper electrode 103 is heated to a predetermined temperature (400 to 600 ° C.) by the heater 601. Thus, carbon nanotubes can be grown on the surface of the upper electrode 103 facing the lower electrode 102. At this time, the inside of the processing chamber 101 is depressurized to a predetermined pressure, and high frequency power is supplied from the high frequency power source 106 to the lower electrode 102 or high frequency power is supplied to the upper electrode 103 so that the lower electrode 102 and the upper electrode 103 Carbon nanotubes may be formed by plasma CVD by generating plasma in between. The high-frequency power source 106 can switch the power supply to either the lower electrode 102 or the upper electrode 103 by switching, for example.

  As described above, by forming carbon nanotubes on the upper electrode 103 provided in the processing chamber 101, when performing various plasma treatments using this plasma processing apparatus, the carbon nanotubes are provided for each predetermined process cycle. Can be newly formed. For example, even in the case of performing the plasma treatment in which the carbon nanotubes are consumed, the state in which the electron supply source 110 is provided on the upper electrode 103 can be maintained by the above.

  In the above description, carbon nanotubes are used as the electron supply source, but the present invention is not limited to this. The material constituting the field emission type electron supply source may be another form of carbon nanostructure such as carbon nanohorn or carbon nanowall. In the above description, carbon nanotubes are grown on a substrate containing iron, nickel, cobalt, chromium, or an alloy thereof. However, according to the CVD method using a carbon source, metal silicide is also used. Carbon nanotubes grow.

The plasma processing apparatus of the present invention described above can be applied to, for example, a plasma etching apparatus that etches an insulating film with plasma using a gas composed of C ₄ F ₈ , Ar, O ₂ . It can also be used as a plasma CVD apparatus. As described above, the plasma processing apparatus of the present invention can be used for processing of silicon constituting an integrated circuit and manufacturing of an organic EL display and a liquid crystal display.

It is typical sectional drawing which shows the schematic structure of the plasma processing apparatus in embodiment of this invention. It is typical sectional drawing which shows the schematic structure of the plasma processing apparatus in other embodiment of this invention. It is typical sectional drawing which shows the schematic structure of the plasma processing apparatus in other embodiment of this invention. It is typical sectional drawing which shows the schematic structure of the plasma processing apparatus in other embodiment of this invention. It is process drawing which shows the manufacturing method example of a carbon nanotube. It is typical sectional drawing which shows the schematic structure of the plasma processing apparatus in other embodiment of this invention. It is a block diagram which shows the structure of the conventional plasma processing apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 ... Processing chamber, 102 ... Lower electrode, 103 ... Upper electrode, 104 ... Gas inlet, 105 ... Gas inlet, 106 ... High frequency power supply, 107 ... Matching device, 110 ... Electron supply source

Claims (6)

In a plasma processing apparatus that performs predetermined processing by the action of plasma generated by generating plasma in a processing container,
A plasma processing apparatus comprising a field emission type electron supply source disposed in the processing container. The plasma processing apparatus according to claim 1,
An anode electrode serving as an anode disposed in the processing vessel;
A cathode electrode disposed opposite to the anode electrode;
Power supply means for supplying power between the anode electrode and the cathode electrode;
Evacuation means for evacuating the processing vessel to reduce the pressure to a predetermined pressure;
A plasma processing apparatus comprising at least a gas introduction part for introducing a desired gas into the processing container. The plasma processing apparatus according to claim 2, wherein
The plasma processing apparatus, wherein the electron supply source is composed of a plurality of carbon nanostructures provided on a surface of the anode electrode facing the cathode electrode. The plasma processing apparatus according to claim 2, wherein
The electron supply source is an electrode structure that is disposed in a region surrounding a space between the anode electrode and the cathode electrode, and is provided with a plurality of carbon nanostructures on a surface facing the space. Plasma processing equipment. The plasma processing apparatus according to claim 3 or 4,
The plasma processing apparatus, wherein the carbon nanostructure is a carbon nanotube. An anode electrode serving as an anode disposed in the processing vessel;
A cathode electrode disposed opposite to the anode electrode;
Power supply means for supplying power between the anode electrode and the cathode electrode;
Evacuation means for evacuating the processing vessel to reduce the pressure to a predetermined pressure;
A plasma processing method using a plasma processing apparatus that includes at least a gas introduction unit that introduces a desired gas into the processing container, and performs a predetermined process by the action of plasma generated by generating plasma in the processing container Because
In the state where the anode electrode is heated, a carbon source gas is introduced into the processing vessel from the gas introduction unit, so that carbon nanotubes are formed on the surface of the anode electrode facing the cathode electrode by chemical vapor deposition. A first step of growing
A predetermined gas is introduced into the processing vessel from the gas introduction part in a state where the inside of the processing vessel is depressurized to a predetermined pressure by the exhaust unit, and power is supplied to the anode electrode and the cathode electrode by the power supply unit. And a second step of generating a plasma of the predetermined gas between the anode electrode and the cathode electrode.

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