JPH1072290A - Device for forming diamond-like carbon thin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device capable of efficiently supplying ions, etc., to form a diamond-like carbon(DLC). SOLUTION: In this device, a gas ion source 10 for generating dissociated carbon and carbon ions and dissociated hydrogen and hydrogen ions is placed opposite to a substrate 3 in a vacuum vessel 1. This gas ion source 10 has a gaseous reactant introduction chamber 11 into which a gaseous reactant is to be introduced and in which plural thermoelectron emission means 12 and plural thermoelectron withdrawal electrodes 13 are one by one alternately arranged. Also, two voltages synchronized with each other are respectively applied to between the substrate 3 and an accelerating electrode 15 and between the thermoelectron emission means 12 and the accelerating electrode 15, with a first bias means 20 and a second bias means 21 respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an apparatus for forming a diamond-like carbon thin film,
In particular, the present invention relates to a diamond-like carbon thin film forming apparatus using a gas ion source.

[0002]

2. Description of the Related Art Conventionally, molds, tools, sliding members,
A diamond-like carbon (DLC) thin film has been used as a hard coating film for protecting the surface of a recording medium or the like of a magnetic disk device. FIG. 12 is a cross-sectional view of a conventional DLC thin film forming apparatus using microwave plasma disclosed in Japanese Patent Application Laid-Open No. 63-185893. In the figure, reference numeral 1 denotes a vacuum chamber for keeping the inside vacuum, 1
Reference numeral 01 denotes a substrate holder for holding the substrate 3 in the vacuum chamber 1;
Is a heater provided on the substrate holder to heat the substrate 3, 103 and 104 are reaction gas inlets for introducing a reaction gas into the vacuum chamber 1, and 102 are for applying microwaves to the vacuum chamber 1. Is an electromagnet for generating a magnetic field in the vacuum chamber 1.

Next, the operation will be described. The substrate 3 is held by the substrate holder 101 in the vacuum chamber 1. Next, the substrate 6 is heated to 300 to 900 ° C. by the heater 6 and the degree of vacuum in the vacuum chamber 1 is reduced to 10 ⁻³ to 10 ⁻⁵ Torr.
To hold. Subsequently, the reaction gas inlets 103 and 104
Supply a reaction gas such as CH ₄ and C ₂ H ₂ into the vacuum chamber 1, apply a magnetic field to the vacuum chamber 1 by the electromagnet 105, and apply a microwave having an output of 300 to 600 W from the waveguide 102. Then, microwave plasma is generated in the vacuum chamber 1, and the excited carbon reaches the substrate 3, thereby forming a DLC thin film on the substrate 3.

[0004]

SUMMARY OF THE INVENTION As described above, the conventional D
In the LC thin film forming apparatus, a gas is supplied to the entire vacuum chamber, and a microwave is applied thereto to form a thin film, so that the efficiency of gas ionization and the like is low. The present invention has been made to solve the above problems, and an object of the present invention is to provide a DLC thin film forming apparatus capable of efficiently supplying ions and the like.

[0005]

In the DLC thin film forming apparatus according to the present invention, the gas ion source includes a reaction gas introduction chamber, a thermionic emission means provided in the reaction gas introduction chamber, and a reaction gas introduction chamber. A plurality of thermionic electron extracting electrodes are provided to extract thermoelectrons from thermionic electron emitting means, and an accelerating electrode for accelerating ions is provided. Thermionic electron extracting electrodes are arranged before and after the thermionic electron emitting means toward the base material. It is a thing.

The gas ion source comprises a reaction gas introducing chamber, a plurality of thermionic emission means, a thermionic extraction electrode, and an accelerating electrode. The thermionic emission means extracts thermionic electrons toward the substrate. These are arranged before and after the electrodes. Further, the gas ion source includes a plurality of thermionic electron emitting means and a plurality of thermionic extracting electrodes, and the thermionic emitting means and thermionic extracting electrodes are alternately arranged in a direction toward the base material. .

Further, there are provided first bias means for applying a voltage to the base material with respect to the accelerating electrode, and second bias means for applying a voltage to the thermionic emission means, each of which applies the voltage as a function of time. You can do it. Further, the constituent materials of the acceleration electrode and the reaction gas introduction chamber are made of graphite.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. FIG. 1 is a cross-sectional view of a diamond-like carbon (DLC) thin film forming apparatus according to a first embodiment of the present invention. In the drawing, reference numeral 1 denotes a vacuum chamber for holding the inside of the vacuum chamber, 2 denotes an exhaust system for evacuating the vacuum chamber 1, and 3 denotes a substrate such as a cemented carbide on which a DLC thin film is formed on the surface. It is held in the vacuum chamber 1 by a holder which is not used. Reference numeral 10 denotes a gas ion source which is provided to face the substrate 3 and generates dissociated carbon and carbon ions, and dissociated hydrogen and hydrogen ions, and 11 internally stores carbon (C) which is a raw material of a DLC thin film. A reaction gas introduction chamber into which a hydrocarbon-based reaction gas containing gas is introduced. The reaction gas introduction chamber is capable of discharging ions and the like, and has an orifice (not shown) so as to increase the flow path resistance and to apply a pressure difference between the reaction chamber and the vacuum chamber 1. ) Is provided in the portion 16 facing the base material 3.

Reference numeral 12 denotes a thermionic emission means provided in the reaction gas introduction chamber 11, which is constituted by a tungsten wire or a tantalum wire. Numeral 13 is a thermoelectron extraction electrode provided in the reaction gas introduction chamber 11 and constituted by a plurality of thin metal wires arranged in parallel. 14 is a reaction gas introduction chamber 11
A reaction gas introduction pipe 15 for introducing a reaction gas into the inside of the reaction gas introduction pipe 15 is an acceleration electrode provided outside the reaction gas introduction chamber 11 to accelerate ions toward the substrate 3. , Thermionic emission means 12, thermionic extraction electrode 13, reaction gas introduction tube 14, and accelerating electrode 15 constitute a gas ion source 10.

Reference numeral 20 denotes a first bias means which can apply a voltage to the base material 3 as a function of time with respect to the acceleration electrode 15;
1 is a second bias means capable of applying a voltage as a function of time to the thermionic emission means 12 to the acceleration electrode 15;
Is a DC power supply for biasing the potential of the thermoelectron extraction electrode 13 in the positive direction with respect to the thermoelectron emission means 12, and 23 is an AC power supply for operating the thermoelectron emission means 12. Vacuum chamber 1, accelerating electrode 15, and first and second bias means 2
One ends of 0 and 21 are grounded.

FIG. 2 is a perspective view schematically showing the arrangement of the thermionic emission means 12 and thermionic extraction electrodes 13. In this figure, the thick arrow indicates the direction in which the reaction gas is ejected, that is, the direction toward the substrate 3, and the thermionic emission means 12 shown in a solid bar shape has a pitch b in the direction perpendicular to the thick arrow, that is, in the horizontal direction.
And four wires arranged in parallel with each other, which are vertically stacked in three stages at a pitch 2a.

Thermionic extraction electrode 1 shown as a dashed bar
Numeral 3 is composed of four wires arranged in parallel at a pitch b in a direction perpendicular to the thick arrow and the wires of the thermionic emission means 12, and they are vertically stacked in three stages at a pitch 2a. I have. The thermoelectron emission means 12 and the thermoelectron extraction electrode 13 are interposed between each other, and are arranged at a pitch a in the vertical direction. Although the figure is simplified for easy viewing, the number of wires is actually increased and used.

FIG. 3 shows an arrangement similar to that of FIG. 2, except that the upper and lower portions of the heat radiating means 12 are shifted laterally by half the pitch, ie, by b / 2. FIG. 4 shows a case where, in addition to the above-described shifting of the thermionic emission means 12, the vertical stacking of the thermionic extraction electrodes 13 is shifted by b / 2 in the horizontal direction.

Next, the operation will be described. First, after the inside of the vacuum chamber 1 is evacuated to a degree of vacuum of about 1 × 10 ⁻⁶ Torr by the exhaust system 2, the base material temperature is adjusted to 100 ° C. to 250 ° C. by a base temperature adjusting mechanism (not shown), and the reaction is performed. A hydrocarbon-based gas, for example, benzene gas, which is a reactive gas, is introduced from the gas introduction pipe 14 into the reaction gas introduction chamber 11, and the gas is ejected toward the thermionic extraction electrode 13 and thermionic emission means 12, thereby causing a reaction. The degree of vacuum in the gas introduction chamber 11 is 1 × 10
Adjust to ^-2 to 1 × 10 ^-1 Torr. Then, power is supplied from the AC power supply 23 to the thermionic emission means 12, and
By heating to about ° C, a state is obtained in which thermoelectrons can be supplied. Next, a voltage of about 50 to 800 V is applied from the DC power supply 22 to bias the potential of the thermoelectron extraction electrode 13 in the positive direction with respect to the thermoelectron emission means 12, and about 1 to 3 A from the thermoelectron emission means 12. The electrons are irradiated toward the thermoelectron extraction electrode 13.

Here, as shown in FIGS. 2 to 4, a plurality of thermionic emission means 12 and thermionic extraction electrodes 13 are provided alternately in the direction toward the substrate, so that thermionic electrons are irradiated. Space can be widened, and since the space is divided, the state of those spaces can be made uniform. The hydrocarbon gas in the reaction gas introduction chamber 11 is excited, dissociated, and ionized by the irradiation of the electrons and the contact with the heated thermionic emission means 12.

At this time, the substrate 3 and thermionic emission means 1
2 is applied with a bias voltage. The voltage V1 (t) applied to the substrate 3 by the first bias means 20 and the voltage V2 (t) applied to the thermionic emission means 12 by the second bias means with reference to the potential of the acceleration electrode 15. 5 to 8 show such examples. For both V1 (t) and V2 (t), the voltage is within ± several kV, and the frequency is several tens Hz to several tens kHz.
And When V2 (t) is positive, ions (positive charges) can be extracted from the reaction gas introduction chamber 11, and when it is negative, electrons can be extracted. Therefore, by controlling the magnitude of the positive and negative bias voltages and the ratio of the time for applying the positive and negative voltages, the kinetic energy and ion amount of carbon ions and hydrogen ions related to film formation, or the charge-up on the substrate 3 Kinetic energy of electrons and the amount of electrons for neutralizing the electrons can be efficiently controlled. Here, the charge-up will be described. D
Since LC is an insulator, a charge-up phenomenon occurs in which ions become positively charged during film formation. When the charges accumulate, discharge occurs, and the film surface is roughened. To suppress this, electrons are supplied to neutralize the charge and improve the flatness of the film.

Further, the kinetic energy and amount of ions and electrons extracted from the gas ion source 10 incident on the substrate 3 can be efficiently controlled by V1 (t). That is,
When V1 (t) is negative, ions can be imparted with energy to enter the substrate 3, and when positive, electrons can be supplied when positive. By controlling the ratio of the time during which the positive and negative voltages are applied, the kinetic energies of carbon ions, hydrogen ions, and electrons and their amounts can be controlled. Also, V1
By synchronizing between (t) and V2 (t) and controlling (V1 (t) -V2 (t)) in total, the kinetic energies of carbon ions, hydrogen ions and electrons and their amounts can be reduced. Can be controlled.

In the case of FIG. 5, a large amount of ions are extracted from the gas ion source 10 while synchronizing between V1 (t) and V2 (t). This shows a case where control is performed. First, in order to extract a large amount of ions from the reaction gas introduction chamber 11 in the excited ionization state, V2 (t) is set to a large bias voltage in the positive direction as shown in FIG. A large amount of ions can be extracted in proportion. At the same time, the ions are decelerated by biasing V1 (t) in the positive direction, as shown in FIG. 9A, and the total, that is, (V1 (t) -V2 (t)) is as shown in FIG. As shown in (c), the kinetic energy of the ions extracted from the gas ion source 10 is controlled to an appropriate level, and the ions are incident on the substrate 3. Note that while V2 (t) is negative, electrons are extracted from the gas ion source 10 and (V1 (t)
-V2 (t)) to enter the substrate 3.

FIG. 6 shows that the kinetic energy of ions is reduced in the case where a mixing layer is formed by injection into the base material 3 or the case where ion sputtering is performed in order to increase the adhesion of the thin film to the substrate 3. This shows a case where a large energy level is set. In order to extract a large amount of ions from the reaction gas introduction chamber 11, V2 (t) is set to a large bias voltage in the positive direction as shown in FIG. At the same time, by setting V1 (t) to a negative bias voltage as shown in FIG. 11A, energy is further applied to the ions, and (V1 (t) -V2 As shown in (t)), a large kinetic energy is applied to the ions to control them to an energy level at which ion sputtering is possible, and the ions are incident on the substrate 3.

FIG. 7 shows a case where V1 (t) and V2 (t) are the alternating voltages, but they are synchronized to have the same magnitude and are set to zero in total. In this case, V2 (t) alternates between positive and negative, and ions and electrons are respectively extracted from the gas ion source 10. However, the ions are decelerated by V1 (t) and ions and electrons are present in the reaction gas introduction chamber 11. Due to the kinetic energy, the light enters the base material 3. FIG. 8 is similar to FIG. 7 except that (V1 (t) -V2
(T)) is a constant negative voltage,
Energy is given to the ions.

Although FIGS. 5 to 8 show a rectangular wave and a sine wave, other waveforms such as a triangular wave may be used. Also, V1
When both (t) and V2 (t) are not DC but voltage that fluctuates with time, it is preferable to synchronize them as shown in FIGS. FIG. 9 shows the results of Raman analysis of the DLC thin film obtained as described above. From the figure,
Has a main peak near 1550 cm ^-1 and 1400 cm ^-1
An asymmetric Raman band having a shoulder band in the vicinity was observed, showing a typical spectrum of DLC, indicating that a high-quality DLC thin film was formed. For comparison, the spectra of the graphite thin film are shown.

As a pretreatment for forming a DLC thin film,
The surface of the substrate 3 may be cleaned. In that case, for example, argon gas suitable for ion cleaning is introduced from the reaction gas pipe 14 into the reaction gas introduction chamber 11,
The degree of vacuum in the reaction gas introduction chamber 11 is changed from 1 × 10 ^-2 to 1 × 10
^-1 Torr. Then, the thermoelectron emission means 12 is operated to irradiate electrons toward the thermoelectron extraction electrode 13, thereby ionizing the gas. The second bias means 21 causes the reaction gas introduction chamber 11 in the excited ionization state to enter the reaction gas introduction chamber 11. From the first bias means 20
The kinetic energy of the ions incident on the substrate 3,
Control the amount. At this time, the first and second bias means 2
By setting the total voltage (V1 (t) -V2 (t)) of 0 and 21 to about -0.5 to -3 kV, the cleaning process can be performed effectively. By the above-described cleaning treatment, impurities such as moisture, oil components, and surface oxides on the surface of the substrate 3 can be removed, and the adhesion between the substrate 3 and the DLC thin film is improved.

Embodiment 2 FIG. FIG. 10 is a cross-sectional view of the DLC thin film forming apparatus according to the second embodiment. The thermoelectron emission means 12 and the thermoelectron extraction electrode 13 are different from those in FIG. Others are the same as those in FIG. One thermoelectron emission means 12 and two thermoelectron extraction electrodes 13 are provided, and the thermoelectron extraction electrodes 13 are arranged before and after the thermoelectron emission means 12 toward the base material 3. With this configuration, the electrons are emitted from the thermionic emission means 12 toward the thermionic extraction electrode 13 as shown by the arrow in the drawing, and the same effect as in FIG. 1 is obtained.

Embodiment 3 FIG. FIG. 11 is a cross-sectional view of the DLC thin film forming apparatus according to the third embodiment. The thermoelectron emission means 12 and the thermoelectron extraction electrode 13 are different from those of FIG. Others are the same as those in FIG. Two thermionic emission means 12 and one thermionic extraction electrode 13 are provided, and thermionic emission means are arranged before and after the thermionic extraction electrode 13 toward the substrate 3. With this configuration, FIG.
The same effect as in the case of is achieved. Embodiments 1 to 3
By using graphite as a constituent material of the accelerating electrode 15 and the reaction gas introduction chamber 11, even if carbon as a reaction product adheres to the inner wall of the reaction gas introduction chamber 11 or the acceleration electrode 15, it is difficult to separate, Can be suppressed.

[0025]

According to the present invention, a DLC thin film forming apparatus comprises:
A gas ion source, a reaction gas introduction chamber, a thermionic emission means provided in the reaction gas introduction chamber, a plurality of thermoelectron extraction electrodes provided in the reaction gas introduction chamber and extracting thermoelectrons from the thermionic emission means, It consists of an accelerating electrode for accelerating ions, and the thermoelectron extraction electrodes are arranged before and after the thermoelectron emitting means toward the substrate, so that the space irradiated with thermoelectrons is wide and uniform. Therefore, the efficiency of the excitation, dissociation, and ionization of the hydrocarbon-based gas that is the reaction gas can be improved, and the dissociated carbon and carbon ions and the dissociated hydrogen and hydrogen ions can be efficiently converted Can be supplied stably. Also, since a reaction gas introduction chamber is provided in the vacuum chamber and gas is introduced into it,
Gas utilization efficiency is improved.

A similar effect can be obtained by providing a plurality of thermionic emission means and arranging them before and after the thermoelectron extraction electrode toward the substrate. Also, by providing a plurality of thermionic emission means, and a plurality of thermionic extraction electrodes, by arranging them alternately in the direction toward the substrate,
A similar effect is achieved.

Furthermore, first and second bias means for applying a voltage to the substrate and thermionic electron emission means are provided, and the voltage is applied as a function of time, whereby the energy amounts of ions and electrons are efficiently controlled. Therefore, a high quality DLC thin film having good adhesion, high hardness and good flatness can be formed. Furthermore, by using graphite as a constituent material of the accelerating electrode and the reaction gas introduction chamber, even if carbon, which is a reaction product, adheres to these, it is difficult to peel off, and generation of dust can be suppressed.

[Brief description of the drawings]

FIG. 1 is a sectional view of a DLC thin film forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing an arrangement of a thermoelectron emitting means and a thermoelectron extraction electrode according to Embodiment 1 of the present invention.

FIG. 3 is a perspective view showing an arrangement of another thermionic emission means and a thermionic extraction electrode according to the first embodiment of the present invention.

FIG. 4 is a perspective view showing the arrangement of still another thermionic emission means and thermionic extraction electrodes according to the first embodiment of the present invention.

FIG. 5 shows first and second embodiments according to the first embodiment of the present invention.
FIG. 6 is a waveform diagram showing an example of a voltage by the bias means.

FIG. 6 shows first and second embodiments according to the first embodiment of the present invention.
FIG. 6 is a waveform diagram showing an example of a voltage by the bias means.

FIG. 7 shows first and second embodiments according to the first embodiment of the present invention.
FIG. 6 is a waveform diagram showing an example of a voltage by the bias means.

FIG. 8 shows first and second embodiments according to the first embodiment of the present invention.
FIG. 6 is a waveform diagram showing an example of a voltage by the bias means.

FIG. 9 is a Raman spectrum diagram showing the results of Raman analysis of a thin film.

FIG. 10 is a sectional view of a DLC thin film forming apparatus according to a second embodiment of the present invention.

FIG. 11 is a sectional view of a DLC thin film forming apparatus according to a third embodiment of the present invention.

FIG. 12 is a sectional view of a conventional DLC thin film forming apparatus.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 vacuum chamber, 3 base material, 10 gas ion source, 11 reaction gas introduction chamber, 12 thermoelectron emission means, 13 thermoelectron extraction electrode, 15 acceleration electrode, 20 first bias means, 21 second bias means, 22 DC power supply.

Claims (5)

[Claims] 1. A thin film forming apparatus for forming a diamond-like carbon thin film on a substrate, comprising: a vacuum chamber for holding the substrate inside while maintaining the inside at a predetermined degree of vacuum; Dissociated carbon and carbon ions,
And a gas ion source for generating dissociated hydrogen and hydrogen ions. The gas ion source is provided with an orifice toward the base material, and a reaction gas introduction chamber into which gas is introduced. A thermionic emission means provided in the introduction chamber to emit thermoelectrons; and a plurality of thermoelectric emission means provided in the reaction gas introduction chamber and having a higher potential than the thermoelectron emission means and extracting thermoelectrons from the thermoelectron emission means. A thermoelectron extraction electrode, and an accelerating electrode provided outside the reaction gas introduction chamber and accelerating the ions toward the base material. An apparatus for forming a diamond-like carbon thin film, which is disposed before and after an electron emitting means. 2. A thin film forming apparatus for forming a diamond-like carbon thin film on a base material, comprising: a vacuum chamber for maintaining the inside of the base material at a predetermined degree of vacuum; and carbon and carbon ions provided opposite to the base material and dissociated. And a gas ion source for generating dissociated hydrogen and hydrogen ions. The gas ion source is provided with an orifice toward the base material, and a reaction gas introduction chamber into which a gas is introduced, and a reaction gas introduction chamber. A plurality of thermionic electron emission means provided in the gas introduction chamber and emitting thermionic electrons; and a thermoelectric electron emission means provided in the reaction gas introduction chamber and given a higher potential than the thermionic emission means. A thermoelectron extraction electrode, and an acceleration electrode provided outside the reaction gas introduction chamber and accelerating the ions toward the base material.The thermoelectron emission electrode is provided on the base material. An apparatus for forming a diamond-like carbon thin film, which is disposed before and after the thermoelectron extraction means. 3. The gas ion source includes a plurality of thermionic emission means and a plurality of thermionic extraction electrodes, and these thermionic emission means and thermionic extraction electrodes are alternately arranged in a direction toward the substrate. 3. The method according to claim 1, wherein
The apparatus for forming a diamond-like carbon thin film according to the above. 4. A first bias means for applying a voltage to the substrate as a function of time to the acceleration electrode, and a second bias means for applying a voltage to the thermionic emission means as a function of time to the acceleration electrode. 4. The diamond-like carbon thin film forming apparatus according to claim 1, further comprising a bias unit. 5. The diamond-like carbon thin film forming apparatus according to claim 1, wherein graphite is used as a constituent material of the acceleration electrode and the reaction gas introduction chamber.