JP2005281727A - Dlc film body manufacturing method and dlc film body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form a thick DLC (diamond-like carbon) film on a surface of a base material to reduce the residual stress in the film. <P>SOLUTION: A base material to be coated is placed in a vacuum container filled with hydrocarbon-based gas, the pulse RF voltage and the high-voltage DC pulse voltage of negative polarity are alternately applied to the base material, the DC pulse voltage is applied after completion of application of the pulse RF voltage, and the pulse-height value of the DC pulse voltage is set to the threshold voltage transferred to the glow discharge. The hydrocarbon-based gas is toluene gas, the gas pressure is set to be 0.1-2 Pa, and the DC pulse voltage is applied in 10-50 μs after completion of application of the pulse RF voltage. The DLC film having the residual stress of the coated base material, which is 0-0.5 GPa is provided. The DLC film having thickness of 1-40 μm is provided. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a surface processing technique for improving friction and wear resistance characteristics of industrial and medical members.

  A diamond-like carbon “DLC (Diamond-Like Carbon)” film used for industrial use is produced by a dry coating technique using a PVD method or a CVD method. FIG. 8 shows a configuration of a DLC film manufacturing apparatus (conventional example 1) using the CVD method currently used. In this apparatus, a base material 1 on which a DLC film is coated through a feedthrough 16 is installed inside a vacuum vessel 11. An RF incident window 23 and an antenna 24 are provided on the upper portion of the vacuum vessel 11, and an RF power source 21a is connected to the antenna 24 via a matching unit 22a. The matching unit 22b is connected to the feedthrough 16 to meet the RF power source 21b. Is connected.

  In addition, toluene gas is supplied into the vacuum vessel 11 from a cylinder 17. The electromagnetic waves radiated from the antenna 24 into the vacuum vessel 11 ionize the toluene gas and turn it into plasma. On the other hand, since a high frequency voltage is applied to the base material 1 by the RF power source 21 b, ions having high energy are extracted from the plasma toward the base material 1. Since radicals generated in plasma reach the surface of the substrate 1 together with ions, a chemical reaction occurs in a thermal non-equilibrium state, and a DLC film is produced.

In addition, the inventor of the present application previously applied a surface modification in which a high-frequency pulse and a negative high-voltage pulse are superimposedly applied to a substrate by a plasma generation power source and a high-voltage pulse generation power source through a common feedthrough. Quality device and reforming method are being developed (conventional example 2). (See JP 2001-26887 A). In this conventional example 2, plasma is generated along the outer shape of the base material, and by applying a negative high voltage pulse to the base material, the ions in the plasma are attracted and injected into the base material. And attracting deposition for forming a thin film on the substrate and attracting collision for sputter cleaning the substrate.
JP 2001-26887 A

  However, the DLC film produced in Conventional Example 1 has a residual stress of about 10 Gpa in the compression direction, and it is difficult to coat a thick film having a thickness of 10 μm or more or a base material that does not have good affinity with DLC.

  The present invention provides a method for producing a DLC film and a DLC film that can form a DLC film thick on the surface of the substrate and reduce residual stress in the film using the apparatus of Conventional Example 2. It is intended to do.

  In order to solve the above problems, a first problem solving means of the present invention is a method, in which a substrate to be coated is placed in a vacuum vessel filled with a hydrocarbon-based gas, and a pulse RF voltage is applied to the substrate. A negative high voltage DC pulse voltage is alternately applied, and after the application of the pulse RF voltage, the DC pulse voltage is applied, and the peak voltage of the DC pulse voltage is set to a threshold voltage for shifting to glow discharge. That is.

  A second problem solving means is a method. In addition to the first method, the hydrocarbon-based gas is toluene gas.

  A third problem solving means is a method. In addition to the first method, the gas pressure of the hydrocarbon-based gas is 0.1 to 2 Pa.

  A fourth problem solving means is a method. In addition to the first method, the DC pulse voltage is applied after 10 to 50 μs has elapsed after the application of the pulse RF voltage.

  The fifth problem solving means is a method. In addition to the first method, the hydrocarbon gas is toluene gas, the gas pressure is 0.1 to 2 Pa, and 10 to 50 μs has elapsed after the application of the pulse RF voltage. After that, a DC pulse voltage is applied.

  A sixth problem solving means is a DLC film, and the residual stress of the coated substrate is 0 to 0.5 GPa.

  The seventh problem solving means is a DLC film, and the residual stress of the coated substrate is 0.1 to 0.5 GPa.

  The eighth problem-solving means is a DLC film, and the residual stress of the coated substrate is zero.

  A ninth problem-solving means is that the DLC film is a coated substrate having a thickness of 1 to 40 μm.

  As described above, the method for producing a DLC film-formed product according to the present invention uses a composite process that combines an ion implantation process and a film-forming process using pulsed plasma using at least one or more hydrocarbon-based gas. A DLC film is formed on the substrate. Further, a surface adjustment process using pulsed plasma may be provided before the combined process.

  A high-frequency power source for plasma generation and a power source for high-voltage pulse generation are connected to the base material in the chamber via a common field through, and the high-frequency pulse (pulse RF voltage) is applied from the high-frequency power source for plasma generation to the base material. Is applied to generate plasma around the outer shape of the substrate.

  Then, a negative high voltage pulse (DC pulse voltage) is applied to the base material from the high voltage pulse generating power source at least once in the plasma or afterglow plasma, and the application of these high frequency pulses and the negative high voltage are applied. The voltage pulse is repeatedly applied. The number of repetitions of the application of the high frequency pulse and the application of the high voltage pulse is, for example, about 100 times / second to 5000 times / second.

  The high-frequency pulse width is a short pulse of 2 to 200 μs, preferably a short pulse of 5 to 20 μs. The high voltage pulse width is a short pulse of 0.2 to 50 μs, preferably a short pulse of 1 to 5 μs. A high voltage pulse is applied after 10 to 50 μs has elapsed since the application of the high frequency pulse.

  The voltage of the high voltage pulse in the ion implantation process by the pulse plasma and the initial film formation stage is set higher than the voltage of the high voltage pulse in the film formation stage after the initial film formation stage, and the application of the high frequency pulse and the high voltage pulse is performed. The number of repetitions may be increased in the film formation stage after the initial film formation stage.

  The voltage of the high voltage pulse in the pulse plasma ion implantation process and the initial film formation stage is set to minus (−) 20 kV, and the voltage in the subsequent film formation stage is set to minus 10 kV.

  A silane coupling agent is added as an impurity at least from the latter stage of the pulse plasma ion implantation process to the first stage of the initial film formation stage. Examples of the silane coupling agent include alkoxide-based agents, such as hexamethyldisiloxane (HMDSO), tetramethylsilane (TMS), tetraethoxysilicon (TEOS), and the like. In particular, the hexamethyldisiloxane is most suitable. In this case, the gas pressure in the chamber at the initial film formation stage in the film formation process is set to 0.3 to 0.5 Pa, and the gas pressure at the subsequent film formation stage is set. Is preferably set to 0.8 to 3 Pa.

  As the surface conditioning gas, a mixed gas containing argon and methane or further hydrogen is used. Methane gas is used as the pulse plasma ion implantation gas. As the film forming gas, one or more gases selected from the group consisting of acetylene, propane, butane, hexane, benzene, chlorobenzene, and toluene are used.

  That is, the surface of the substrate is cleaned by molecular collision in argon gas having a large molecular weight among the surface conditioning gases, and the surface is adjusted by adhesion of carbon atoms and hydrogen atoms in methane gas to the substrate surface.

  Then, methane gas is used as a pulse plasma ion implantation gas to inject carbon monoatomics into the substrate, and then a film is formed by colliding two or more carbon atoms such as acetylene and propane with the substrate as a film forming gas. It is.

  Nitrogen gas may be used before methane gas is used as the pulse plasma ion implantation gas. In this case, the nitrogen atom implanted into the substrate has a function of preventing the subsequently implanted carbon atoms from diffusing into the substrate.

  The base material includes all finished products and parts that require DLC film formation, and specifically includes prototype molds, tools, hard disks, semiconductor manufacturing parts, golf club heads, automobile parts, and the like. .

  The base material may be an insulating material such as plastic, rubber and ceramics in addition to a conductive material such as metal (iron or the like).

  The base material can be a low melting point alloy such as a zinc alloy, an aluminum alloy, or a magnesium alloy. In the film forming method of the present invention, each process of ion implantation and DLC film formation is basically performed by pulsed plasma, so that the temperature of the substrate during film formation can be kept low, and DLC into a low melting point alloy is achieved. Film formation can be realized.

  When the base material is an insulating material, each treatment is performed with the base material held in a holder made of a conductive material.

  A DLC film-formed product is a DLC film-formed product in which a DLC film is directly formed on the surface of a base material. Carbon atoms are injected from the surface of the base material to a predetermined depth, and the interface between the base material and the DLC film. Is formed with an inclined layer of implanted atoms and carbon atoms, wherein the implanted atoms in the substrate and the carbon atoms of the DLC film are covalently bonded, and the carbon atoms in the DLC film are aligned. .

  According to the present invention, the residual stress of the DLC film is made extremely small by making the magnitude of the peak value voltage of the negative high voltage DC pulse voltage coincide with the threshold voltage at which glow discharge is generated by the DC pulse voltage. In addition, a thick film coating of 10 μm or more and a coating on a substrate that does not have a good affinity with DLC are also possible.

Hereinafter, embodiments of the present invention will be described based on an example shown in the drawings.
In FIG. 1, in this apparatus, a base material 1 on which a DLC film is coated via a feedthrough 16 is installed inside a vacuum vessel 11. Toluene gas, which is a raw material gas, is supplied to the vacuum vessel 11 to the gas supply tank 17, and the gas pressure is set within a range of 0.1 to 2 Pa. A pulse RF power source 12 for generating a pulse RF voltage is connected to the feedthrough 16 via a matching unit 13, and a high voltage pulse power source 3 for applying a negative DC pulse voltage to the substrate 1 is passed through a filter 14. Connected. Here, the filter 14 is for protecting the pulse RF voltage from entering the high voltage pulse power supply 3. The operations of the pulse RF power supply 13 and the high voltage pulse power supply 3 are controlled by a synchronization signal generator 15.

  As shown in FIG. 2, the superimposing device 9 couples between the feedthrough 16 and the high voltage pulse generating power source 3, as well as a pulse RF power source (plasma generating power source) 12 and a high voltage pulse power source (high voltage pulse power source). The power generation unit 3 includes a coupling / mutual interference prevention circuit 19 that prevents mutual interference with the power generation unit 3, and a matching circuit unit 17 that matches the impedance between the plasma generation power source 12 and the substrate 1.

  The coupling / mutual interference blocking circuit 19 generates an arc discharge by a high voltage pulse, and the high frequency power from the gap G1, the plasma generating power source 12 for conducting the circuit affects the high voltage pulse generating power source 3. A diode D and a coil L1 for blocking, and a resistor R and a protection gap G2 for preventing a high voltage pulse from the high voltage pulse generating power source 3 from affecting the plasma generating power source 12 are provided. The gap G1 may be short-circuited when the pulse application voltage is low. In the coupling / mutual interference blocking circuit 19 in the superimposing device 9, the cathode side of the diode D is connected to the high voltage pulse generating power source 3. The non-ground side end of the resistor R is connected to the plasma generating power source 12 by the coaxial cable 18. The diode D may be omitted.

  The matching circuit unit 17 includes a resonance variable capacitor C1, an impedance conversion capacitor C2, a high voltage capacitor C3, and a coil L2. Since the capacitor C2 is connected in parallel to the resistor R, the non-grounded end is also connected to the plasma generating power source 12 by the coaxial cable 18.

  The terminal on the gap G1 side of the high-resistance capacitor C3 is connected to the feedthrough 16 and the gap G1 conductor on the substrate 1 side.

  The plasma generating power source 12 applies a high frequency pulse to the substrate 1 based on control by a CPU (matching unit) 13. The high voltage pulse generating power source 3 applies a negative high voltage pulse to the substrate 1 based on control by the CPU 13.

The residual stress of the produced DLC film was measured by the cantilever method shown in FIG. In this measuring method, a strip-shaped base material is supported by a holder, and the residual stress is measured by curving the sample. The result is the graph of FIG. 6, in which the horizontal axis represents the peak voltage V _PP (kV) of the DC pulse voltage and the vertical axis represents the residual stress σ (GPa). The base material used for the measurement was a quartz substrate (Young's modulus 76.2 GPa, Poisson's ratio 0.14) having a thickness of 0.5 mm. This substrate was placed in the apparatus and a DLC film was formed on the surface. The film forming condition at this time was a gas pressure of 0.5 Pa.

  As shown in FIG. 4, the power supply conditions were such that the input voltage, power, and pulse width of the pulse RF voltage were 1 to 2 kV, 100 W, and 50 μs, respectively, and the pulse width of the DC pulse voltage was 5 μs. The output frequency of the pulse RF voltage was 13.56 MHz and the repetition oscillation frequency was 500 Hz. The DC pulse voltage was applied 50 μs after the fall of the pulse RF voltage. Then, the combination of application of the pulse RF voltage and application of the DC pulse voltage was repeated 3.6 million times (total of 2 hours).

As can be seen from FIG. 6, when the residual stress σ of the DLC film changes the peak voltage V _PP of the DC pulse voltage, the residual stress σ is almost from 0.27 GPa in the region where | V _PP | is 0 to 5 kV. Linearly decreases to 0.2 and 0.1, and in the region of 5 kV to 7 kV, the residual stress σ becomes zero (0) or approaches zero as much as possible.

That, | V _PP | In <7 kV region (ion implanted region) decreased with the absolute value of V _PP increases, becomes V _PP = At -5 kV sigma = 0 GPa. On the other hand, in the region of | V _PP |> 7 kV (glow discharge region), the absolute value of V _PP increased and the residual stress σ increased. In this region, as shown in FIG. 3, the behavior of plasma in the vicinity of the substrate, the amount of electron current due to secondary electrons emitted from the substrate is greater than the ion current caused by the acceleration of ions occurring in the sheath region 5. Therefore, glow discharge occurs in the vicinity of the substrate, the voltage applied to the sheath is lowered, and the effect of ion implantation is reduced.

  FIG. 7 is a graph in which the horizontal axis represents the gas pressure pg (Pa) and the vertical axis represents the threshold voltage Vsh (kV). From this, it can be seen that when the gas pressure is increased from 0.2 Pa to 2 Pa, the threshold voltage decreases from approximately | 12 | kV to | 0.1 | kV. The area above the graph line is considered to be a glow discharge region, and the lower part is considered to be an ion implantation region. And the ion implantation efficiency is the best in the region (boundary region) near this graph line.

  The film thickness obtained under the power supply conditions (FIG. 4) was 0.5 μm, and the temperature during the film forming operation was about 100 ° C. The DLC film formation rate at this time was about 0.25 μm / h. The film forming operation was performed for 4 hours when the film thickness was 1 μm and for 160 hours when the film thickness was 40 μm.

  The present invention is not limited to the examples and embodiments described above, and includes various modifications without departing from the scope and scope of the claims.

  The present invention is used for a method of manufacturing a DLC film-formed product and a DLC film-formed product.

1 is an overall view of a device configuration according to an embodiment of the present invention. It is an electric circuit diagram of the principal part of FIG. It is operation | movement explanatory drawing in the base-material vicinity of FIG. It is an operation | movement sequence diagram which concerns on one Example of this invention. It is a front view which shows an example of a residual stress test. It is a pulse voltage dependence graph example figure of the residual stress based on the Example of this invention. It is an example of a discharge characteristic graph concerning one example of the present invention. It is explanatory drawing which shows the conventional DLC film production apparatus.

Explanation of symbols

1 Object (base material)
2 Thin Film 3 High Voltage Pulse Power Supply 4 Plasma 5 Sheath 6 Radical 7 Ion 8 High Voltage Pulse Power Supply 11 Vacuum Container 12 Pulse RF Power Supply 13 Matching Device 14 Filter 15 Synchronization Signal Generator 16 Feedthrough 17 Toluene Gas Cylinder 21a RF Power Supply 21b RF Power Supply 22a Matching device 22b Matching device 23 RF incident window 24 Antenna

Claims (9)

The substrate to be coated is placed in a vacuum container filled with hydrocarbon gas,
A pulse RF voltage and a negative high voltage DC pulse voltage are alternately applied to the substrate,
Apply DC pulse voltage after application of pulse RF voltage,
A method for producing a DLC film-formed product, wherein the peak voltage of the DC pulse voltage is set to a threshold voltage for shifting to glow discharge. The method for producing a DLC film-formed product according to claim 1, wherein the hydrocarbon-based gas is toluene gas. The method for producing a DLC film-formed product according to claim 1, wherein a gas pressure of the hydrocarbon-based gas is 0.1 to 2 Pa. After 10-50 μs has elapsed after the application of the pulse RF voltage,
The method for producing a DLC film-formed product according to claim 1, wherein the DC pulse voltage is applied. 2. The hydrocarbon gas according to claim 1, wherein the hydrocarbon gas is toluene gas, the gas pressure is 0.1 to 2 Pa, and a DC pulse voltage is applied after 10 to 50 [mu] s has elapsed after the application of the pulse RF voltage. A method for producing a DLC film. A DLC film-formed product in which the residual stress of the coated substrate is 0 to 0.5 GPa. A DLC film-formed product in which the residual stress of the coated substrate is 0.1 to 0.5 GPa. DLC film with zero residual stress on coated substrate A DLC film-formed product having a coated substrate thickness of 1 to 40 μm.

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