JP4376659B2 - Plasma processing method - Google Patents

Description

  The present invention relates to a plasma processing method for depositing desired ions on an object to be processed made of a conductor, and more particularly to a plasma processing method in which the object to be processed is applied to a hollow object.

  As a conventional plasma processing method, plasma is uniformly applied to a three-dimensional shape by applying a high frequency of 13.56 MHz for plasma generation and a negative high voltage of a direct current pulse for controlling a plasma ion sheath to a workpiece. There was a thing to process (refer to patent documents 1).

  FIG. 5 is an explanatory diagram of an example of a conventional plasma processing method.

  In FIG. 5, 1 is a part to be processed, 2 is a vacuum vessel, 3 is a conductor, 4 is a high voltage introduction unit, 5 is a high voltage pulse generating power source, 6 is a superimposing device, and 7 is a plasma generating power source.

  The object to be processed 1 has been processed so that desired ion implantation and film formation are uniform in a vacuum vessel 2 in which plasma is uniformly generated for a three-dimensional substance.

That is, plasma is generated by the workpiece 1 and the plasma generation power source 7, and the plasma generation power source 7 is switched from the plasma generation power source 7 to the high voltage pulse generation power source 5 via the superposition device 6, so that the shape of the workpiece 1 is uniform The desired ions were implanted.
JP 2001-26887 A (FIG. 1)

  However, in the above-described conventional configuration, since the object to be processed itself can generate plasma and control the sheath thickness, the directivity by the plasma source can be reduced, but it is difficult to control the sheath thickness to less than 20 mm.

  In particular, in order to uniformly treat the inside of the hollow object to be processed formed of a conductor, it is necessary to make the sheath thickness less than 1/2 of the hollow inner diameter, so if the control of the sheath thickness is 20 mm, For example, there is a problem that only a workpiece having a cylindrical diameter of 40 mm or more can be processed.

  The present invention solves the above-mentioned conventional problems, and provides a plasma processing method that makes it possible to uniformly plasma-process the inside of a hollow object to be processed formed of a conductor having an inner diameter of less than 10 mm. The purpose is to do.

In order to achieve the above object, the plasma processing method of the present invention basically arranges a hollow object to be processed in a vacuum vessel, introduces a desired gas into the vacuum vessel, and performs the hollow object to be processed. By applying a high frequency voltage to an electrode arranged concentrically in the hollow interior of the object, plasma is generated in the hollow interior of the hollow object, and a negative voltage is applied to the hollow object. In the plasma processing method for plasma processing the hollow interior of the hollow object to be processed, a plurality of the hollow objects to be processed are coaxially connected, and an insulator is provided between the hollow objects to be processed. This is a processing method in which a hollow spacer is provided to perform the plasma processing .

  According to the plasma processing method of the present invention, it is possible to uniformly perform plasma processing on the inside of a hollow object to be processed formed of a conductor whose inner diameter is less than 10 mm.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 is a configuration diagram of a plasma processing apparatus for explaining the first embodiment of the present invention.

  In FIG. 1, a hollow object 11 made of a conductor that is electrically connected to a negative high voltage power supply 13 is set in a predetermined position in a vacuum container 12, and the hollow object 11 is placed inside the hollow object 11. Are arranged concentrically with electrodes 14 made of a conductor electrically connected to a high-frequency power supply 15 via a phase matching unit 16.

  According to the first embodiment, by arranging the hollow object 11 to be processed and the electrode 14 concentrically, it becomes possible to generate plasma uniformly inside the hollow of the object 11 to be processed. 11 can be uniformly plasma-treated.

  The relationship of (P (R−r)) / 2 between the pressure P of the raw material gas containing the desired ions to be introduced and the inner diameter R and the outer electrode diameter r of the workpiece 11 is Paschen's law. Is designed to show a value greater than the curve according to

  For example, when the inner diameter R of the object to be processed 11 is 10 mm and the outer diameter r of the electrode 14 is 1 mm, uniform plasma is generated inside the object 11 by setting the pressure P of the source gas to 30 pa or more. It is possible to generate.

In the present embodiment, C ₁₀ H ₈ is used as a source gas and the purpose is to uniformly form a film mainly composed of carbon _. After applying −10 kV to the object 11, 13 _. By applying a high frequency of 56 MHz to generate plasma, an injection layer mainly composed of carbon was formed on the surface layer of the object 11 to be processed, and a film mainly composed of carbon could be uniformly formed.

  Note that although an example in which a carbon electrode is provided as the electrode 14 has been described in the present embodiment, the electrode may be a conductive substance.

(Embodiment 2)
FIG. 2 is a process flow diagram of the plasma processing method according to the second embodiment of the present invention. The apparatus shown in FIG. 1 was used as the implementation apparatus in the second embodiment.

As shown in FIG. 2, in Embodiment 2, CH ₄ is introduced as a source gas (S 1), a voltage of −15 kV is applied to the object 11 (S 2), and then a high frequency of 13.56 MHz is applied to the electrode 14. To generate plasma (S3), and after forming an injection layer mainly containing carbon in the hollow inside of the object 11 to be processed, the source gas is switched to C ₁₀ H ₈ (S4). A voltage of −2 kV was applied, and a film mainly composed of carbon was formed inside the workpiece 1 (S5).

  In the first and second embodiments, it is possible to improve the depth and concentration of the injection layer by separating the step of forming the injection layer from the step of forming the film, and the adhesion strength of the film mainly composed of carbon. Can be improved.

  In the first and second embodiments, the frequency applied to the electrode 14 is preferably 100 kHz to 2.8 GHz. If the frequency is lower than 100 kHz, plasma having a sufficient plasma density cannot be generated in the hollow object 11, and if the frequency is higher than 2.8 GHz, the power source becomes expensive and countermeasures against electromagnetic waves are required.

  In addition, the voltage applied to the hollow object 11 is desirably -30 kV to -200 V. If it is less than −200 V, sufficient adhesion to the deposited film cannot be obtained, and if it is −30 kV or more, the deposited film is damaged and the film quality is deteriorated.

In the case where the film to be formed is a DLC film mainly composed of carbon, C ₆ H ₆ , CH ₄ , and C ₂ H ₂ are generally used as source gases for ion generation. In this plasma processing method, it was confirmed that a DLC film was generated even when a polymer gas containing other carbon such as C ₁₀ H ₈ was used. Accordingly, there is an advantage that a DLC film can be generated without using a high environmental load gas such as C ₆ H ₆ . Specifically, C ₆ H ₆ , CH ₄ , C ₂ H ₂ , C ₁₀ H ₈ , CH ₃ OH, C ₂ H ₅ OH, CH ₃ OHCH ₃ , C ₁₀ H ₁₆ O and the like containing conventional source gases Can be appropriately selected and used.

  In the second embodiment, the voltage applied to the workpiece 11 in the pre-process of step (S2) is set to −30 kV to −5 kV, thereby improving the adhesion of the formed film. However, sufficient adhesion cannot be obtained. Further, by adjusting the voltage applied to the object to be processed in the subsequent process of step (S5) to −5 kV to 0 V, the film quality is adjusted at the time of film formation. Outside this range, the film formed is damaged. And deteriorates the film quality.

Further, as in the reference example shown in FIG. 3, it is also conceivable to perform the plasma treatment by arranging a plurality of hollow objects 11 to be concentrically arranged. By doing in this way, the to-be-processed object 11 can be processed efficiently in space-saving, and productivity improves.

Further, as shown in FIG. 4, in the case where a plurality of hollow workpieces 11 are arranged concentrically, a hollow insulator 20 is provided between the workpieces 11 in the first and second embodiments. Similarly, by concentrically interposing, when the aspect ratio of the workpiece 11 is 2 or less, the plasma generated in each insulator 20 portion can wrap around the hollow interior of the workpiece 11 and is uniform. A plurality of workpieces 11 can be processed.

  The plasma processing method of the present invention provides a uniform and highly adherent film by uniformly injecting and forming desired ions into a hollow object to be processed formed of a conductor connected to a negative high voltage power source. And can be applied to the surface modification of a rocking part such as a motor.

Configuration diagram of plasma processing apparatus for explaining Embodiment 1 of the present invention Process flow diagram of plasma processing method of embodiment 2 of the present invention Explanatory drawing which shows the example of arrangement | positioning of the hollow to-be-processed object in a reference example . Explanatory view showing a distribution置例the hollow object to be processed in this embodiment Illustration of an example of a conventional plasma processing method

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Hollow to-be-processed object 12 Vacuum container 13 Negative high voltage power supply 14 Electrode 15 High frequency power supply 16 Phase matching device 20 Insulator

Claims (8)

Place the hollow object to be processed in the vacuum container,
Plasma is introduced into the hollow interior of the hollow object by introducing a desired gas into the vacuum container and applying a high-frequency voltage to electrodes concentrically arranged inside the hollow object. To generate
By applying a negative voltage to the hollow object to be processed, the pulp plasma processing method to the plasma treatment a hollow interior of the hollow object to be processed,
A plasma characterized in that a plurality of the hollow objects to be processed are connected in a coaxial manner, and a hollow spacer made of an insulator is disposed between the hollow objects to be processed to perform the plasma treatment. Processing method . Disposing a hollow object to be processed in a vacuum container, and concentrically arranging electrodes inside the hollow of the hollow object to be processed,
A first desired gas is introduced into the vacuum container, and a high frequency voltage is applied to the electrode to generate plasma in the hollow interior of the hollow object to be processed. A pre-process for applying a voltage;
A second desired gas is introduced into the vacuum vessel, and a high-frequency voltage is applied to the electrode to generate plasma in the hollow interior of the hollow object to be processed. by a step after applying a more absolute value is low negative voltage, the pulp plasma processing method to the plasma treatment a hollow interior of the hollow object to be processed,
A plasma characterized in that a plurality of the hollow objects to be processed are connected in a coaxial manner, and a hollow spacer made of an insulator is disposed between the hollow objects to be processed to perform the plasma treatment. Processing method . The plasma processing method according to claim 1, wherein the electrode is made of a conductive material .   The product of (R−r) / 2, which is ½ of the difference between the inner diameter R of the hollow object to be processed and the outer diameter r of the electrode, and the pressure P of the introduced raw material gas is 3. The plasma processing method according to claim 1, wherein the plasma processing method is larger than a value of a curve indicated by a law.   The plasma processing method according to claim 1, wherein a frequency applied to the electrode is 100 kHz to 2.8 GHz.   3. The plasma processing method according to claim 1, wherein a voltage applied to the hollow workpiece is −30 kV to −200 V. 4. The ion generation source gas is selected from C ₆ H ₆ , CH ₄ , C ₂ H ₂ , C ₁₀ H ₈ , CH ₃ OH, C ₂ H ₅ OH, CH ₃ OHCH ₃ , and C ₁₀ H ₁₆ O. 3. The plasma processing method according to claim 1, wherein the plasma processing method is performed. 3. The plasma processing method according to claim 2, wherein the voltage applied to the object to be processed in the previous process is -30 kV to -5 kV, and the voltage applied to the object to be processed in the subsequent process is -5 kV to 0 V.

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