JP4925600B2 - Plasma generator and film forming method using the same - Google Patents

Description

  The present invention relates to a plasma generator and a film forming method using the same.

In the conventional plasma generator, a coil is wound around the outer periphery of a chamber, and a current is supplied to the coil from a high frequency power source to generate plasma in the chamber (see Patent Document 1). In such a plasma generator, it is necessary to supply high frequency power from a high frequency power source to the coil via an impedance matching circuit. Therefore, in order to form a film on the surface of a long wire using this plasma generator, it is necessary to install a large number of impedance matching circuits and extend the coil to lengthen the plasma. A large-scale and costly plasma generator is required.
JP 2004-216246 A

  The present inventor has eagerly studied to provide a novel plasma generator that is not bound by the existing concept so as to make it possible to lengthen the plasma by extending the coil without the need to install an impedance matching circuit. Repeated.

  As a result of the research, the present inventor can complete an invention capable of generating and maintaining a plasma in a long and stable state for a long time by extending a coil without the necessity of installing an impedance matching circuit. It came.

  That is, the plasma generating apparatus according to the present invention is a conductive material having one or a plurality of continuous or independent openings from one end side to the other end side of the peripheral wall in a decompressed chamber under a plasma generating gas atmosphere. A cylindrical body is disposed, and a negative potential of a DC power source is applied to one end side of the cylindrical body, and a substantially same potential as the positive potential of the DC power source is applied to the space inside the chamber outside the cylindrical body. It is a feature.

  An example of the cylindrical body having one continuous hole is a coil. Moreover, as a cylindrical body having a plurality of independent openings, for example, there is a cylindrical body having a meshed peripheral wall. The coil has a spiral space between the wires. The shape of the cylindrical body may be any shape that can be generated in a state in which the plasma column is confined in the space in the cylindrical body.

  The plasma generation method of the present invention is different from the existing concept of a high frequency plasma method in which high frequency power is applied to both ends of a coil to generate plasma and a direct current plasma method in which a direct current power source is connected to both ends of the coil. The coil is configured so that a negative voltage of a DC power source is applied to one end side of the cylindrical body, and the other end side of the coil is in a floating state without connecting the DC power source to the other end side of the cylindrical body. A plasma column can be generated and confined in the inner space.

  In such a plasma generator according to the present invention, there is no need to install an impedance matching circuit on the extension path even if the coil is extended, so that the extension of the coil is very simple and the apparatus is simple. In addition to being inexpensive, it is possible to provide a plasma generating apparatus that can generate a plasma column stably and for a long period of time by arbitrarily lengthening it.

  Particularly noteworthy in the present invention is that a stable plasma column can be stably generated over a long period of time in a state of being confined in a space surrounded by a coil, as clearly demonstrated with reference to the photograph. is there.

  In the present invention, it should be further noted that, as an example of its application, a film-forming gas such as a carbon compound gas is introduced into the chamber to form a carbon film on the surface of a long film-forming target such as a wire. When forming a film, the film can be formed simply by extending the coil according to the size of the film formation target and placing the film formation target inside the coil, thereby significantly reducing the film formation cost compared to the conventional method. Can do.

  An object formed by forming a carbon film having a large number of fine protrusions on the surface of the wire is used as a cathode, and electrons are emitted by applying an electric field between the cathode and the anode. Excitation light can be emitted. The present invention can be used particularly effectively when such a wire-like cold cathode electron source is elongated and a large-sized cold cathode electron source is manufactured at low cost.

  By using the plasma generator of the present invention, various plasma processing apparatuses such as a plasma CVD apparatus, a plasma etching apparatus, and a plasma plating apparatus can be obtained.

  That is, in the plasma generator of the present invention, as described above, a carbon film is formed on the surface of a film to be formed, such as a wire, and carbon such as methane or ethylene, which is a film forming gas, is formed in the chamber. By introducing a compound-based gas, a plasma CVD apparatus for forming a film on a film formation target can be obtained.

  Further, the plasma generator of the present invention can be a plasma etching apparatus that etches an object to be etched by introducing an etching gas into the chamber.

  Furthermore, the plasma generating apparatus of the present invention can be a plasma plating apparatus for plating an object to be plated by introducing a plating gas into the chamber.

  According to the present invention, it is a novel and original and epoch-making capable of generating a long plasma column in a state where it is stably confined in a predetermined space even though the manufacturing is simple and inexpensive. A plasma generating apparatus can be provided.

  Hereinafter, a plasma generator according to an embodiment of the present invention will be described with reference to the accompanying drawings. The plasma generator 10 includes a cylindrical chamber 12 made of metal such as SUS. The meaning of the metal includes that the chamber 12 itself may be made of metal, but the outer peripheral wall surface of the chamber 12 is covered with an insulating material from the viewpoint of safety, and the inner peripheral wall surface is made of metal. be able to. The metal material for the chamber 12 is not particularly limited.

  The chamber 12 is grounded. The chamber 12 is provided with a gas inlet 14 and a gas outlet 16. The plasma generating gas may be an active gas or an inert gas. The active gas is, for example, hydrogen gas, and the inert gas is, for example, argon gas. The pressure in the chamber may be in the range of 10 Pa to 10000 Pa, and can be appropriately set within this range.

  A metal coil 18 is disposed inside the chamber 12. The material of the coil 18 is not particularly limited, but there is, for example, SUS.

  One end of the coil 18 is connected to the negative electrode of the DC power supply 20 and is applied with a negative potential. The positive electrode of the DC power supply 20 is grounded. Thereby, the space in the chamber 12 is at the same potential as the positive potential of the DC power supply 20. The other end side of the coil 18 is floating. The other end side of the coil 18 does not necessarily need to float, and the other end side of the coil 18 may be connected to one end side thereof. The wire diameter of the coil 18 is not particularly limited, but is, for example, 2 mm to 25 mm. The distance between the coils 18 is not particularly limited, and is, for example, 2 mm to 20 mm. These wire diameters and spacings between the wires can be appropriately determined by experiments or the like. In the experiment of the present inventor, although there was a difference in the above range, any of them could be carried out.

  In other words, the coil 18 is a conductive cylindrical body surrounded by a peripheral wall having a spiral opening. Since the coil 18 has a spiral shape, the opening has a continuous hole shape from one end side to the other end side of the coil 18. Although not shown, instead of the coil 18, a conductive cylindrical body surrounded by a peripheral wall having a mesh-like opening may be used. The thickness and roughness of the mesh can be appropriately determined by experiments or the like.

 The DC power supply 20 is preferably a voltage variable type. The voltage of the DC power supply 20 is in the voltage range of 100V to 2000V. The voltage of the DC power supply 20 can be appropriately determined by experiments or the like.

  In the plasma generating apparatus 10 having the above configuration, when the inside of the chamber 12 is depressurized and hydrogen gas is introduced as a plasma generating gas from the gas introduction port 14, and the negative potential of the DC power supply 20 is applied to the coil 18, the coil 18 A plasma column 24 is generated in the internal space.

  FIG. 2 is a photograph showing a state in which the plasma 24 is generated in the internal space of the coil 18 by the plasma generator 10 corresponding to the present embodiment manufactured by the present inventor and disposed in the laboratory. The photograph in FIG. 2 (a) is for the DC power supply 20 with a negative voltage of 700V, methane / hydrogen gas, and a pressure of 80Pa, and the photograph in FIG. 2 (b) is the DC power supply 20 with a negative voltage of 700V, methane / hydrogen gas. The pressure is 170 Pa. The material of the coil 18 is SUS. Although a code cannot be taken in the photograph, the coil 18, the wire 22, and the plasma column 24 are clearly photographed.

  A method of forming a film on an object to be formed which is a long object such as a wire using the plasma generator 10 will be described. The conductive wire 22 is disposed inside the coil 18. An AC power supply 23 is connected to both ends of the wire 22 to heat the wire 22. Hydrogen gas as plasma generating gas and methane gas as carbon film forming gas for the surface of the wire 22 are introduced from the gas inlet 14. When the chamber internal pressure is reduced and the negative potential of the DC power supply 20 is applied to the coil 18, a plasma column 24 is generated in the internal space of the coil 18, whereby methane gas is decomposed and a carbon film is formed on the surface of the wire 22. Is deposited. In the photograph of FIG. 2, the wire 22 is disposed in the internal space of the coil 18, and a carbon film can be formed on the surface of the wire 22.

  FIG. 3 is a diagram showing a configuration of a plasma generator 10 according to another embodiment of the present invention. The plasma generator 10 shown in FIG. 3 is different from the plasma generator 10 shown in FIG. That is, the positive electrode of the DC power supply 20 is provided inside the chamber 12. Also in the plasma generator 10 shown in FIG.

It is a figure which shows the structure of the plasma generator which concerns on embodiment of this invention. It is a photograph which shows a mode that the plasma column is generate | occur | produced by the plasma generator which concerns on embodiment of this invention. It is a figure which shows the structure of the plasma generator which concerns on other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Plasma generator 12 Chamber 14 Gas inlet 16 Gas outlet 18 Coil 20 DC power supply 22 Wire 24 Plasma column

Claims (3)

A conductive coil is placed in a chamber under a reduced-pressure plasma generating gas atmosphere, a negative potential of a DC power supply is applied to one end of the coil, and the positive side of the DC power supply is grounded together with the chamber The plasma generation is characterized in that a positive potential side of the DC power supply is applied to the space in the chamber outside the coil by placing a positive electrode side of the DC power supply in the chamber space. apparatus. In a film forming method for forming a film on the surface of a conductive wire,
2. The plasma generator according to claim 1, wherein a conductive wire is disposed in a space in the coil, both ends of the conductive wire are connected to an AC power source, the pressure in the chamber is reduced, and plasma is generated in the chamber. A gas and a film forming gas are introduced, a negative electrode side potential of a DC power supply is applied to one end of the coil to generate a plasma column in the space in the coil, and a film is formed on the surface of the conductive wire. A film forming method characterized by the above. The film forming method according to claim 2, wherein the film forming gas is a carbon-based gas.