JP2014237890A - Film deposition apparatus of diamond-like carbon film and formation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film deposition apparatus of a diamond-like carbon film capable of shortening a time required for film deposition, and improving a film quality, and to provide a formation method thereof.SOLUTION: A gas control part 22 is constituted so as to control so that carrier gas is supplied from a carrier gas feed source 20 into a flow route 14 until the flow route 14 reaches a film deposition temperature, and that, when the flow route 14 reaches the film deposition temperature, gas for film deposition is supplied from the carrier gas feed source 20 and a hydrocarbon gas feed source 18 into the flow route 14 at a prescribed flow rate so that a carbon source is contained at a prescribed concentration.

Description

The present invention relates to a diamond-like carbon film forming apparatus and method, and more particularly to a diamond-like carbon film forming apparatus and method having a relatively high sp ³ / sp ² structure ratio.

  In addition to properties such as hardness and slidability, diamond-like carbon (Diamond Like Carbon, hereinafter also referred to as “DLC”) having excellent heat resistance, fusing resistance, and welding resistance and an extremely flat surface. The film has been put into practical use as a hard coating material such as a tool.

  It is widely known that a DLC film can be produced at a low temperature using a plasma CVD (Chemical Vapor Deposition) apparatus.

  However, the plasma CVD apparatus has a drawback that the apparatus itself is complicated and the apparatus introduction cost is high.

  Therefore, an atmospheric pressure pyrolysis method that enables creation of a DLC film in atmospheric pressure is being developed (see, for example, Patent Documents 1 and 2).

Japanese Patent No. 50000283 JP 2008-260670 A

  However, the conventional method for forming a DLC film by the atmospheric pressure pyrolysis method requires, for example, one hour or more for the film formation.

  That is, when a DLC film is formed on a relatively large sample surface, there is a problem that a long reaction time is required to supply hydrocarbons necessary for the reaction because it is necessary to increase the amount of DLC per unit surface. there were.

  In addition, when methane is used as a carbon source, there is a disadvantage in that soot-like unnecessary carbon remains on the surface of the formed DLC film.

  The present invention has been made to solve the above-described problems, and can provide a diamond-like carbon film forming apparatus capable of reducing the time required for film formation and improving the film quality. An object is to provide a forming method.

In order to solve the above problems, a diamond-like carbon film forming apparatus according to the present invention includes:
A carrier including a deposition target for forming a diamond-like carbon film, a flow path for flowing a film forming gas and a gas other than the film forming gas, and any of hydrogen gas, nitrogen gas, and argon gas A carrier gas supply source for supplying gas to the flow path at a predetermined flow rate; and a carbon source gas supply source for supplying a carbon source comprising any one of a ketone body, an alcohol or a carboxylic acid to the flow path at a predetermined flow rate; A gas control unit for controlling a gas flow rate from the carrier gas supply source and the carbon source gas supply source to the flow path, a heating unit for increasing the temperature of the flow path, and a temperature in the flow path being predetermined. A temperature control unit that controls the heating unit to reach a temperature, and the gas control unit transfers the carrier gas to the carrier until the flow path reaches a film formation temperature. Supply gas to the flow path from the gas supply source, and supply the film forming gas to the carrier gas so that a carbon source is included at a predetermined concentration when the flow path reaches the film formation temperature. Control is performed so that a predetermined flow rate is supplied from the gas source and the hydrocarbon gas supply source to the flow path.

  The method of forming a diamond-like carbon film according to the present invention includes a step of disposing a film formation target for forming a diamond-like carbon film in a flow path for flowing hydrogen gas, and the hydrogen gas at a predetermined flow rate. Flowing the flow path through the flow path and raising the film formation target from room temperature to a predetermined temperature; and when the predetermined temperature is reached, the hydrogen gas is used as a carrier gas to form a ketone body, alcohol or carboxylic acid as a carbon source. The method includes a step of flowing a film forming gas containing any of them at a predetermined concentration in the flow path for a predetermined time, and a step of maintaining the predetermined temperature state for a predetermined time.

  According to the present invention, the following effects can be obtained.

That is, according to the diamond-like carbon film forming apparatus of the present invention, the sp ³ / sp ² structure ratio is 0.32 to 0.5, and the half-value width of the G band peak in Raman spectroscopy is 70 cm. ^When it is ⁻¹ or less, a diamond-like carbon film having excellent properties with high hardness and high resistivity can be obtained.

  In addition, according to the method for forming a diamond-like carbon film according to the present invention, the time required for film formation can be greatly reduced as compared with the case where methane is used as the carbon source.

  In addition, when impurities are removed from the surface of the film formation target by reducing the hydrogen gas by flowing hydrogen gas before flowing the film formation gas, the surface of the film formation target is cleaned. The film formation quality can be improved.

  In addition, when a predetermined catalyst is applied to the surface of the film formation target, the film formation temperature can be lowered.

  In addition, when unnecessary carbon remaining on the surface of the diamond-like carbon film on the object to be deposited is removed by flowing hydrogen gas after the diamond-like carbon film is formed, the film-forming quality is reduced. This can be further improved.

(A) is a schematic diagram explaining the concept of the film-forming apparatus which concerns on embodiment, (b) is sectional drawing which shows the state in which the DLC film was formed in the film-forming target object. It is a schematic diagram which shows schematic structure of a tubular electric furnace. It is a graph which shows the relationship between the temperature in an electric furnace and time of the film-forming experiment example using the film-forming apparatus which concerns on embodiment. It is a schematic diagram which shows the production | generation method of the gas for film-forming. It is a graph which shows the Raman spectrum of the DLC film formed into a film on the predetermined conditions (Acetone hot water bath temperature: 60 degreeC, thermal decomposition temperature: 1200 degreeC) in embodiment. It is a graph which shows the XPS spectrum of the DLC film formed into a film on the predetermined conditions (Acetone hot-water bath temperature: 60 degreeC, thermal decomposition temperature: 1200 degreeC) in embodiment. 4 is a graph showing the relationship between the sp ³ / sp ² structure ratio in a DLC film formed under a predetermined condition and the half width (fwhm) of a G peak in an embodiment. In the embodiment, the thermal decomposition temperature (with and without the catalyst) of the comparative example using the DLC film and methane formed under predetermined conditions (acetone bath temperature: 50 ° C., 60 ° C.) and Raman shift It is a graph which shows the relationship with G peak position. Thermal decomposition temperature (with and without catalyst) and G-peak of comparative example using DLC film and methane formed under predetermined conditions (acetone bath temperature: 50 ° C., 60 ° C.) in the embodiment It is a graph which shows the relationship with a half value width. Thermal decomposition temperatures (in the case of no catalyst and in the presence of a catalyst) and Raman of a comparative example using a DLC film and methane formed under predetermined conditions (acetone bath temperature: 50 ° C., 60 ° C.) in the embodiment It is a graph which shows the relationship of ratio of area intensity of G peak of a spectrum, and D peak, and I (D) / I (G) ratio. In the embodiment, a thermal decomposition temperature (with and without catalyst) of a comparative example using a DLC film and methane formed under predetermined conditions (acetone bath temperature: 50 ° C., 60 ° C.) and sp ³ / is a graph showing the relationship between the sp ² structure ratio. It is a graph which shows the relationship between the thermal decomposition temperature and optical band gap of the comparative example using the DLC film and methane which were formed into a film on the predetermined conditions (acetone hot water bath temperature: 50 degreeC, 60 degreeC) in embodiment. It is a figure which shows schematic structure of an acetone collection apparatus. It is a graph which shows the relationship between the thermal decomposition temperature and resistance value of the comparative example using the DLC film | membrane and methane which were formed into a film on the predetermined conditions (acetone hot water bath temperature: 50 degreeC, 60 degreeC) in embodiment. Predetermined condition in the embodiment (acetone water bath temperature: 50 ℃, 60 ℃) is a graph showing the relationship between the in sp 3 ^/ sp ² structure ratio of the formed DLC film and the electrical resistivity.

Hereinafter, an embodiment as an example of the present invention will be described in detail with reference to the drawings. Here, in the accompanying drawings, the same reference numerals are given to the same members, and duplicate descriptions are omitted. In addition, since description here is the best form by which this invention is implemented, this invention is not limited to the said form.
[Embodiment of Method for Forming DLC Film]
The DLC film forming method according to the embodiment includes the following forming steps (a) to (d). That is,
(A) a step of disposing a film formation target for forming a diamond-like carbon film in a flow path for flowing hydrogen gas;
(B) flowing the hydrogen gas through the flow path at a predetermined flow rate and raising the film formation target from room temperature to a predetermined temperature;
(C) When the predetermined temperature is reached, a film-forming gas containing any one of a ketone body, an alcohol, or a carboxylic acid that is a carbon source at a predetermined concentration using the hydrogen gas as a carrier gas is predetermined in the flow path. Flowing over time,
(D) maintaining the state of the predetermined temperature for a predetermined time;
It is.

In the present embodiment, acetone (CH ₃ COCH ₃ ) was used as the ketone body as the carbon source.

  As the ketone body, aldehyde or the like can be used in addition to acetone. Moreover, it can replace with a ketone body and alcohols, such as methanol and ethanol, can also be used.

  The film formation target can be made of a predetermined ceramic or a predetermined metal. As the ceramic, alumina, silica, or the like can be used. As the metal, iron, molybdenum steel, or the like can be used.

  Further, before flowing the film forming gas, a process of removing impurities by reducing the hydrogen gas on the surface of the film forming target may be provided by flowing hydrogen gas.

  A predetermined catalyst may be applied to the surface of the film formation target. The predetermined catalyst can be applied at a predetermined concentration.

  Moreover, it is preferable that the said predetermined temperature shall be 1000-1400 degreeC.

Further, after the DLC film is formed, there may be a step of removing unnecessary carbon remaining on the surface of the DLC film on the deposition target by flowing hydrogen gas.
[Basic Configuration of Film Forming Apparatus According to Embodiment]
A basic configuration of a film forming apparatus according to an embodiment capable of performing the above forming method is as follows.

That is, the film forming apparatus according to the embodiment arranges a film forming target for forming a diamond-like carbon film, and flows a film forming gas and a gas other than the film forming gas,
A carrier gas supply source that supplies a carrier gas containing any one of hydrogen gas, nitrogen gas, and argon gas to the flow path at a predetermined flow rate, and a carbon source that includes a ketone body, an alcohol, or a carboxylic acid gas is predetermined. A carbon source gas supply source that supplies the flow path at a flow rate, a gas control unit that controls a gas flow rate from the carrier gas supply source and the carbon source gas supply source to the flow path, and a temperature of the flow path is increased. And a temperature control unit that controls the heating unit so that the temperature in the flow path becomes a predetermined temperature, the gas control unit until the flow path reaches the film formation temperature, The carrier gas is controlled to be supplied from the carrier gas supply source to the flow path, and a carbon source is included at a predetermined concentration when the flow path reaches the film formation temperature. A has a configuration for controlling to supply a predetermined flow rate to the flow path of the deposition gas from the carrier gas supply source and the hydrocarbon gas supply source.

  Further, the gas control unit can control to supply the carrier gas supplied from the carrier gas supply source to the flow path after the film formation is completed.

  Further, the gas control unit may control to change the type of the carrier gas before and after the film formation.

  Moreover, it is preferable that the said film-forming temperature is 1000-1400 degreeC.

  The molar ratio of the film forming gas other than the carbon source and the film forming gas is preferably 0.18 to 0.30: 1.0.

  The ketone body can be acetone.

  The gas supply by the carrier gas supply source and the gas control unit may be performed via bubbling.

Further, the film formation target can be made of a predetermined ceramic or a predetermined metal.
[Configuration Example of Film Forming Apparatus According to Embodiment]
A structural example of a film forming apparatus capable of performing the above forming method will be described with reference to FIGS.

  FIG. 1A is a schematic diagram for explaining the concept of the film forming apparatus according to this embodiment, and FIG. 1B is a cross-sectional view showing a state in which a DLC film is formed.

  As shown in FIG. 1A, the film forming apparatus 10 according to the present embodiment includes a gas supply source 12, a flow path 14 for flowing a gas supplied from the gas supply source 12, a gas supply source 12, and And a control unit 16 that controls the flow path 14.

The gas supply source 12 includes an acetone gas supply source 18 as a carbon source and a hydrogen gas (H ₂ gas) supply source 20 as a carrier gas.

  The flow path 14 is provided with a furnace 26 on which the film formation target 30 is placed.

  The control unit 16 is composed of, for example, a microcomputer and has a gas control unit 22 and a temperature control unit 24.

  The gas control unit 22 is configured to control the mixing ratio of the acetone gas and the hydrogen gas and adjust the flow rate of the mixed film forming gas RG.

The temperature control unit 24 is configured to control the temperature of the film forming gas RG.
(Arrangement process)
In the present embodiment, a tubular electric furnace 26 as shown in FIG. 2 can be used as the furnace provided in the flow path 14.

  A furnace core tube 28 is inserted into the tubular electric furnace 26 so that a film forming gas RG and hydrogen gas are circulated.

  In the furnace core tube 28, a ceramic or metal film formation target 30 to be a DLC film formation target is placed.

  As the ceramic, for example, alumina or silica can be applied.

  Examples of the metal film formation target 30 include metal objects (such as metal members and metal parts) such as SKD11, S45C, SKH51, SNCM439, SUS304, and SCM440. SKD11 is suitable for use in a drill rod, and SKH51 is suitable for use in high speed steel. SCM440 is chrome molybdenum steel and is suitable for use as a structural steel, and S45C is suitable for use as a steel pipe.

  Further, instead of the ceramic or metal film formation object, a film formation object made of sapphire glass or the like can be used.

(Impurity removal / film formation process)
After the film formation target 30 is arranged, hydrogen gas is circulated through the flow path 14 over a period of time T1 shown in FIG. In the experimental example shown in FIG. 3, the flow rate of hydrogen gas was 50 ml / min.

  FIG. 3 is a graph showing the relationship between the temperature in the electric furnace and time in a film forming experiment example using the film forming apparatus 10 according to the present embodiment.

  Next, a process of heating the film formation target 30 from room temperature to a predetermined temperature by the electric furnace 26 over a period of time T1 shown in FIG.

  In the example shown in FIG. 3, the time T1 is about 240 minutes.

In the step of circulating the hydrogen gas, impurities present on the surface 30f of the film formation target 30 are removed by the reducing action of the hydrogen gas. That is, impurities are removed in the form of a gas such as H ₂ O or CO ₂ by reaction with hydrogen gas. Thereby, the surface 30f of the film-forming target 30 can be kept clean.

  Then, a film-forming gas RG made of a mixed gas of hydrogen gas and acetone gas is circulated for a period of time T2 shown in FIG. 3 from the time point when the temperature control unit 24 determines that the predetermined temperature has been reached.

  In addition, in the experimental example shown in FIG. 3, the predetermined temperature was tried by seven types of temperature (about 800 to 1400 degreeC) of 100 to C intervals of AG.

  In the example shown in FIG. 3, the time T2 is about 10 minutes.

  As described above, the film formation target surface 30f and the film formation gas RG are reacted by bringing the film formation target gas RG containing acetone gas into contact with the film formation target surface 30f while holding the film formation target 30 at a predetermined temperature. Thus, the DLC film 34 (see FIG. 1B) is formed on the film formation target surface 30f.

  The upper limit of the predetermined temperature is regulated by the heat resistant temperature of the film formation target 30 (that is, the temperature at which the film formation target 30 does not melt with heat). The lower the predetermined temperature is, the simpler or lower the cost of the apparatus configuration of the film forming apparatus.

  In the example shown in FIG. 3, the time T2 required for film formation is about 10 minutes, and the film formation time is significantly longer than the film formation time (about 2 hours) when methane gas is used as the carbon source. It can be shortened. Thereby, the DLC film can be efficiently formed, and the cost can be reduced.

  Next, after the film formation process at time T2 is completed, hydrogen gas is circulated again under the control of the gas control unit 22 over a period of time T3 shown in FIG. Thereby, even when unnecessary carbon (soot) adheres to the DLC film 34 formed on the film formation target 30, it can be removed by reacting with hydrogen gas, and the quality of the DLC film is improved. Can do.

  Thereafter, the electric furnace 26 is opened and the film formation target 30 is taken out from the electric furnace 26. At that time, an inert gas or a nitrogen gas is allowed to flow through the flow path 14 at the end of the film formation process to remove hydrogen gas and the like, and after the film formation target 30 in the electric furnace 26 is cooled to room temperature, the electric furnace 26 Is preferably opened.

  Since the DLC film 34 formed in this way is formed by a hydrocarbon pyrolysis method, as compared to a DLC film prepared by a plasma method, G peak, D, as will be described later in Raman scattering spectroscopy. Both peaks are observed remarkably.

  In addition, since a commercially available electric furnace 26 can be used instead of the tubular electric furnace 26, the film-forming target 30 can be used in a case where the dimension of the film-forming target 30 is larger than that when a film is formed using an apparatus such as plasma CVD. A DLC film can be formed.

  In addition, regarding the flow rate of the film forming gas RG, if the flow rate is too large, the temperature of the film forming gas RG decreases, and considering the efficient use of the film forming gas RG, the film formation target surface 30f ( It is preferable to flow the deposition gas RG so as to contact the deposition surface RG as slowly as possible. However, if the flow rate is too small, carbon as a raw material for the DLC film may not be sufficiently supplied. Therefore, the flow rate is set to an appropriate flow rate in consideration of the dimensions of the electric furnace 26 and the film formation target 30.

  In the present embodiment, for convenience of description, the case where the DLC film 34 is formed on the film formation target surface 30f on one side has been described. However, if the film formation target surface is in contact with the film formation gas RG, the film formation is performed. Is possible.

  That is, as indicated by the two-dot chain line and the solid line in FIG. 1B, the DLC film 34 can be formed on the entire surface of the film formation target 30 in contact with the film formation gas RG.

  Alternatively, the DLC film 34 may be formed by applying a catalyst (for example, fine particles of Ni, Fe, Co, etc.) to the film formation target surface 30f.

The DLC film 34 can be formed within a thickness range of about 1 to 10 μm.
[Method of generating gas for film formation]
With reference to the schematic diagram of FIG. 4, a method for generating a film forming gas will be described.

In the example shown in FIG. 4, liquid acetone 63 contained in a container 61 is immersed in a hot water bath container 60, and hydrogen gas (H ₂ ) is bubbled in a hot water bath at a predetermined temperature to generate a film forming gas RG. After that, the electric furnace 26 is supplied via the supply pipe 70.

In addition, hydrogen gas (H ₂ ) can be supplied independently to the electric furnace 26 via the supply pipe 71.

  In addition, the experiment was conducted at a predetermined temperature for bathing at 50 ° C. set lower than the boiling point of acetone (56 ° C.) and 60 ° C. set higher than the boiling point, as described later.

By applying the film forming gas generation method shown in FIG. 4, according to the graph of FIG. 3 described above, at time T1, hydrogen gas (H ₂ ) is independently supplied through the supply pipe 71 to the electric furnace. 26.

  Next, when the electric furnace 26 is heated and reaches a predetermined temperature, the film-forming gas RG generated as described above is supplied to the electric furnace 26 through the supply pipe 70 during the period of time T2.

Next, after the elapse of time T2, hydrogen gas (H ₂ ) is supplied alone to the electric furnace 26 again through the supply pipe 71 over the period of time T3.

As described above, the DLC film can be formed on the film formation target 30 by switching the gas supplied to the electric furnace 26 at a predetermined timing.
[Evaluation results of the formed DLC film]
5 to 12 show the evaluation results of the DLC film formed under the predetermined conditions in the present embodiment.

  FIG. 5 is a graph showing a Raman spectrum of a DLC film formed under predetermined conditions (acetone bath temperature: 60 ° C., thermal decomposition temperature: 1200 ° C.) in the embodiment.

As shown in FIG. 5, in the Raman scattering spectroscopy using a commonly used visible light laser, it can be seen that the formed DLC film has two peaks at 1333 cm ⁻¹ and 1584 cm ⁻¹ .

In graphite (not shown), one sharp peak is observed at 1584 cm ⁻¹ , and this vibration mode is called G-band after the initial of Graphite.

In addition, graphite has a large phonon density in the region near 1333 cm ^−1, but is not Raman-active, so no peak is observed in highly crystalline graphite. However, when a defect is introduced, a Raman peak is observed, and this peak is called a D-band as a defect-derived peak.

  Because it is derived from defects, it is observed with high strength in graphite, amorphous, and nanoparticles with low crystallinity.

Further, even in the same carbon crystal, a sharp peak appears at 1333 cm ⁻¹ in the vibration mode of diamond having a crystal structure different from that of graphite, which is used for evaluating the crystallinity of microcrystals and thin films.

  In other words, a carbon material such as diamond or graphite that does not have a complete crystal structure has two Raman peaks, which are sharper as the crystallinity increases and show a peak with a narrow half-value width.

Compared with the relative sensitivity of the broad D-band near 1333 cm ⁻¹ in the DLC film, the relative sensitivity of the sharp single peak at 1333 cm ⁻¹ observed in diamond is very low, so diamond with slightly DLC In Fig. ¹ , only one sharp peak at 1333 cm ^-1 is observed.

Therefore, as shown in FIG. 5, the film formed under the predetermined conditions (acetone bath temperature: 60 ° C., thermal decomposition temperature: 1200 ° C.) in the embodiment is one sharp 1333 cm ⁻¹ characteristic of diamond. No peak is observed, and there are broad peaks at two locations of 1333 cm ⁻¹ and 1584 cm ⁻¹ . Thereby, it can be determined that the DLC film according to the present embodiment is a characteristic DLC film having a characteristic that the amount thereof is limited although it has a diamond-like property.

  FIG. 6 is a graph showing an XPS spectrum (waveform separation for C1s) of a DLC film formed under predetermined conditions (acetone bath temperature: 60 ° C., thermal decomposition temperature: 1200 ° C.) in the embodiment.

Here, waveform (A) is the original data (Raw Intensity), (B) is the background, and (C) and (D) are the waveforms of sp ² and sp ³ separated from the original data (A). It is.

As shown in FIG. 6, a sharp peak appears at 284 eV. This is considered to have detected the 1s electron of carbon of sp ² orbital.

Further, a certain peak appears in the vicinity of 285 eV. This is considered to have detected the 1s electron of carbon of sp ³ orbital.

In addition, it is known that carbon in sp ³ orbital includes carbon by C—C bond bonded to carbon in diamond and carbon by C—H bond bonded to hydrogen.

Therefore, as shown in FIG. 5, in the embodiment, the film formed under the predetermined conditions (acetone bath temperature: 60 ° C., thermal decomposition temperature: 1200 ° C.) has sp ² orbital properties that are normal carbon. It can be seen that carbon is included due to the C—H bond in which carbon and diamond-like sp ³ orbital carbon and hydrogen are bonded.

FIG. 7 is a graph showing the relationship between the sp ³ / sp ² structure ratio in the DLC film formed under the predetermined conditions and the half width (fwhm) of the G peak in the embodiment.

In FIG. 7, the horizontal axis represents the sp ³ / sp ² ratio obtained from the XPS spectrum, and the vertical axis represents the half width (cm ⁻¹ ) of the G peak obtained from the Raman spectrum.

  The film formation conditions plotted in FIG. 7 are the following four types.

○: Without catalyst, methane + Ar (10% + 90%) Treatment temperature: 1000, 1100, 1200, 1300 ° C.
A: Without catalyst, hot water bath temperature 50 ° C. acetone + hydrogen 50 ml Treatment temperature: 1200, 1300, 1400 ° C.
□: without catalyst, hot water bath temperature 60 ° C. acetone + hydrogen 50 ml treatment temperature: 1000, 1200, 1300, 1400 ° C.
●: With catalyst, hot water bath temperature 50 ° C. Acetone + hydrogen 50 ml Treatment temperature: 1100, 1200, 1300, 1400 ° C.
■: With catalyst, hot water bath temperature 60 ° C. Acetone + hydrogen 50 ml Treatment temperature: 1000, 1100, 1200, 1300, 1400 ° C.
In addition, it formed into a film on the ceramic substrate as a film-forming target object by reaction of methane + Ar for 1 hour and acetone for 10 minutes.
As a method of applying the catalyst, a dropping method is used, and the amount of the catalyst is 1/10 (8.18 × 10 ¹³ = 1) of the number of surface atoms (about 8.18 × 10 ¹⁴ ) of the ceramic in order to have the function. Prepare a nitrate aqueous solution by dissolving nickel nitrate (II) hexahydrate, iron nitrate (III) nonahydrate, and cobalt nitrate (II) hexahydrate in distilled water so as to be 36 × 10 ⁹ mol) did. These nitrates are reduced by hydrogen at elevated temperatures and remain on the substrate as pure metal clusters.

From FIG.
(1) When acetone + hydrogen is used as a raw material in a hot water bath at 50 ° C. (◎ and ●), sp ³ / sp ² takes a larger value than DLC (◯) prepared with methane + Ar.
(2) When acetone + hydrogen is used as a raw material in a hot water bath of 60 ° C. (□ and ■), sp ³ / sp ² takes a slightly smaller value (0.26 ± 0) than DLC (◯) prepared with methane + Ar. .04 → 0.20 ± 0.04).
(3) When acetone is used, the fwhm value of the G peak always takes a smaller value than when methane + Ar.

  I understand that.

Then, the present inventor stated that, based on FIG. 7, the DLC film formed by the film forming apparatus according to the present embodiment has a sp ³ / sp ² structure ratio of 0.32 to 0.5. The knowledge was derived.

  FIG. 8 shows the thermal decomposition temperature of a comparative example using a DLC film and methane formed under predetermined conditions (acetone bath temperature: 50 ° C., 60 ° C.) in the film forming apparatus according to the embodiment (in the case of no catalyst). And a graph showing the relationship between the G peak position of the Raman shift and the case where there is a catalyst.

  When the DLC film formed on the ceramics without a catalyst is examined based on FIG. 8, from the respective results, the hot water bath temperature of 50 ° C. and the hot water bath temperature of 60 ° C. are almost in the graphite region at 1000 ° C., 1000 to 1300 ° C. Then, it can be seen from nc-graphite (nano-crystalline Graphite) that the region is amorphous carbon (a-C).

  FIG. 9 shows a thermal decomposition temperature of a comparative example using a DLC film and methane formed under a predetermined condition (acetone hot water bath temperature: 50 ° C., 60 ° C.) in the embodiment (without catalyst and with catalyst). And the G-peak half width (fwhm).

  FIG. 10 shows the thermal decomposition temperature of a comparative example using a DLC film and methane formed under predetermined conditions (acetone bath temperature: 50 ° C., 60 ° C.) in the film forming apparatus according to the embodiment (in the case of no catalyst). And the ratio of the area intensity of the G peak and D peak of the Raman spectrum, and the I (D) / I (G) ratio.

Here, when the DLC film made of acetone without a catalyst is compared with the DLC film made of methane, the following items (1) to (5) can be understood.
(1) In DLC produced with methane, the G peak position, I (D) / I (G) ratio, and Gpeak full width at half maximum do not change much even when the production temperature is changed from 1000 ° C to 1300 ° C. In the DLC film fabricated in (1), the change in these values is large.
(2) As the film formation temperature rises, the G peak half width decreases, and a DLC film with high crystallinity is produced.
(3) Even if the bath temperature is 50 ° C. or 60 ° C., there is no significant difference in DLC characteristics.
(4) The G peak position of the DLC film produced at 1300 ° C. is lower than 1575 cm ⁻¹ of graphite and exhibits the characteristics of amorphous carbon (a-C).
(5) When produced at 1400 ° C., it is considered that graphite is produced.

Further, when the characteristics of the DLC film due to the difference in hot water bath temperature are examined, the following items (6) and (7) can be understood.
(6) There is almost no difference in the characteristics of the DLC produced without the catalyst.
(7) Regarding the characteristics of the DLC produced by applying the catalyst, a difference is seen in the film produced at 1400 ° C. Specifically, when produced at 60 ° C., the G peak, I (D) / I (G) ratio, and G peak half-value width are larger than those produced at 1300 ° C. In spite of the temperature of 1400 ° C. produced, it is suggested that a large amount of acetone is supplied, resulting in a broken graphite crystal.

Further, when the characteristics of the DLC film with and without the catalyst are examined, the following item (8) can be found.
(8) When there is no catalyst, the G peak position is lower than 1575 cm ^{−1 of} graphite in the film prepared at 1300 ° C. or higher, and shows the characteristics of amorphous carbon (a-C).

In particular, based on the above item (2), the present inventor has found that the half-width of the G band peak in the Raman spectroscopy of the DLC film formed according to the present embodiment is 70 cm ⁻¹ or less. The knowledge of was derived.

FIG. 11 shows a thermal decomposition temperature of a comparative example using DLC film and methane formed under predetermined conditions (acetone bath temperature: 50 ° C., 60 ° C.) in the film forming apparatus according to the embodiment (in the case of no catalyst). And the sp ³ / sp ² structure ratio.

From FIG. 11, the following items (1) to (4) can be understood by comparing the DLC film made of acetone without a catalyst with the DLC film made of methane.
(1) The same sp ³ / sp ² ratio (0.2 to 0.3) can be obtained as compared with a film made of methane.
(2) A thin film produced at a hot water bath temperature of 50 ° C. and a heating temperature of 1200 ° C. has a large sp ³ / sp ² ratio of 0.4.
(3) XPS measurement could not be performed on a thin film produced at a hot water bath temperature of 50 ° C. and a heating temperature of 1100 ° C.
(4) A particularly large sp ³ / sp ² ratio was obtained in a film produced at a hot water bath temperature of 60 ° C. and a heating temperature of 1100 ° C. (In this sample, a peak considered to be CO ₃ etc. on the high BE side of the C1s spectrum) There is a high possibility that the surface sp ³ / sp ² ratio is changed by the reaction with the oxygen atom O).

Further, the following item (5) can be understood with respect to the characteristics of the DLC film depending on the difference in the bath temperature.
(5) In the DLC film prepared by applying the catalyst, the film having a hot water bath temperature of 50 ° C. has a larger sp ³ / sp ² ratio (when the hot water bath temperature is 60 ° C., the amount of supplied carbon is large and stable. It is thought that a sp ² carbon is generated).

Further, the following item (6) can be understood as to the characteristics of the DLC film depending on the presence or absence of a catalyst.
(6) In a DLC film produced by applying a catalyst, the sp ³ / sp ² ratio of the produced film does not change even if the heating temperature changes if the bath temperature is the same (the reaction is sufficiently fast) Is thought to imply that).

  FIG. 12 shows the thermal decomposition temperatures of Comparative Examples 1 and 2 using a DLC film and methane formed under predetermined conditions (acetone bath temperature: 50 ° C., 60 ° C.) in the embodiment (in the case of no catalyst, It is a graph which shows the relationship between an optical band gap and a case with a catalyst.

From FIG. 12, the following items (1) and (2) can be understood.
(1) Regarding the optical band gap, a value of about 1.5 to 2.0 [eV] is taken at all thermal decomposition temperatures regardless of the presence or absence of a catalyst.
(2) The value of pyrolysis of acetone is higher than the value of pyrolysis of methane (Comparative Examples 1 and 2).

The following items (a) to (g) can be grasped collectively from the evaluation results shown in FIGS.
(A) Even when no metal catalyst was used, the film could be formed in 10 minutes.
(B) The effect of the catalyst related to the film formation was clearly confirmed at a hot water bath temperature of 50 ° C. and a thermal decomposition temperature of 1100 ° C.
(C) It was found that when a catalyst was used, the film thickness increased, but without the use of a catalyst, there was no film peeling.
(D) It was found that the film quality was changed by the catalyst.
(E) If no catalyst was used, it was found that no change due to the bath temperature was observed at the thermal decomposition temperatures of 1300 ° C and 1400 ° C.
(F) It was found that the ratio of carbon sp ³ was highest when the temperature of the hot water bath using the catalyst was 50 ° C.
(G) It was found that the optical band gap value was higher than the thermal decomposition of methane, regardless of the presence or absence of a catalyst.
[Acetone: hydrogen ratio when the bath temperature is 50 ° C. and 60 ° C.]
Next, the measurement which calculated | required the ratio of acetone: hydrogen when the hot water bath temperature is 50 degreeC and 60 degreeC is described.
(Measurement method)
The amount of hydrogen was 50 ml / min, and the measurement method was performed using a hydrogen digital flow meter.

  And the amount of hydrogen which flowed for a fixed time from the gas equation of state was calculated as the number of moles.

  About the amount of acetone, it carried out using the acetone collection apparatus 200 shown in FIG.

  As shown in FIG. 13, the acetone collection device 200 immerses a pipe 203 having a U-shaped tube 203 a through which liquid nitrogen 202 is placed in a container 201 and a mixed gas of hydrogen and acetone vapor is circulated therein. ing.

  Here, in the apparatus of FIG. 4 described above, hydrogen vapor is bubbled at a hot water bath temperature of 50 ° C. or 60 ° C., and acetone vapor cooled at room temperature by the supply pipe 70 is supplied to the electric furnace 26.

Then, the acetone vapor is circulated through the pipe 203 of the acetone collecting device 200, passed through the U-shaped tube 203a, collected in a liquid nitrogen trap for a certain period of time, measured as a liquid, measured in weight, and converted into the number of moles. The amount was calculated.
The measurement results were as follows.

Acetone: hydrogen (molar ratio)
When the bath temperature is 50 ° C .: 0.20: 1.0
When the bath temperature is 60 ° C .: 0.29: 1.0
Even if the bath temperature is 60 ° C. (temperature exceeding the boiling point), the reason why the acetone: hydrogen ratio is not so different from that at 50 ° C. is presumed to be as follows.

That is, in the apparatus shown in FIG. 4, when the bath temperature is 60 ° C., acetone vapor exceeding the boiling point is vigorously supplied. However, most of the acetone vapor is cooled and liquefied in the upper part of the supply pipe 70 and returns to the container 60, and the remaining acetone vapor is supplied into the electric furnace 26 by hydrogen gas. For this reason, it is considered that the amount of acetone is not so large as compared with the case of 50 ° C. even when the bath temperature is 60 ° C.
(Relationship between thermal decomposition temperature and resistance value)
Next, FIG. 14 shows the thermal decomposition temperature and resistance of a comparative example using a DLC film and methane formed under predetermined conditions (acetone bath temperature: 50 ° C., 60 ° C.) in the film forming apparatus according to the embodiment. It is a graph which shows the relationship with a value.

  The resistance value shown in FIG. 14 is obtained by the following formula 1 as the electrical resistivity ρ and sheet resistance ρs [Ω / cm] of the film by using the IV characteristic and the film thickness t that can be measured by the four-point probe method. be able to.

ρ = Ft × (V / I) Equation 1
Here, F is a resistivity correction coefficient (= π / ln2).

The resistivity of the DLC film produced in this embodiment is on the order of 10 ⁻³ to 10 ⁻⁴ , and the DLC produced in the comparative example (methane pyrolysis method) is on the order of 10 ⁻⁵ , so acetone is used. The produced DLC has a high resistivity and is considered to be more semiconducting.
(Sp ³ / sp ² ratio and electrical resistivity in DLC film)
FIG. 15 shows the relationship between the electrical resistivity and the sp ³ / sp ² structure ratio of a DLC film formed under predetermined conditions (acetone bath temperature: 50 ° C., 60 ° C.) in the film forming apparatus according to the embodiment. It is a graph to show.

In FIG. 15, the horizontal axis represents the sp ³ / sp ² ratio obtained from the XPS spectrum, and the vertical axis represents the electrical resistivity.

  The film formation was carried out on a ceramic substrate by reacting methane + Ar for 1 hour and acetone for 10 minutes.

Here, conditions such as hot water bath temperature,
□: hot water bath temperature 50 ° C. acetone + hydrogen 50 ml 1100, 1200, 1300, 1400 ° C.
○: Bath temperature 60 ° C. Acetone + Hydrogen 50 ml 1000, 1100, 1200, 1300, 1400 ° C.
It is.

  Further, by using the IV characteristics and the film thickness t that can be measured by the four-probe method, the electrical resistivity ρ and sheet resistance ρs [Ω / cm] of the film can be obtained as shown in Equation 2.

ρ = Ft × (V / I) = ρst Equation 2
Here, F is a resistivity correction coefficient (= π / ln2).

The following items (1) and (2) can be understood from the results shown in FIG.
(1) When the bath temperature is 50 ° C., the electrical resistivity decreases as the value of sp ³ / sp ^{2 in} the formed DLC film increases. It is expected that the electrical resistivity of sp ³ carbon is higher than that of sp ² carbon. The reason why the results different from these predictions were obtained is that the value of sp ³ / sp ² measured by XPS is the value of the surface only, and includes information on carbon bonded to hydrogen in addition to carbon bonded to carbon. In contrast, the resistance measured by the four-probe method is considered to be the entire inside of the film.
(2) When the bath temperature is 60 ° C., the value of sp ³ / sp ^{2 in} the formed DLC film is substantially constant, and the electrical resistivity varies depending on the temperature at which the DLC is produced.

  In the case of no catalyst, the film is thin, the film thickness cannot be obtained, and the electrical resistivity ρ cannot be obtained.

  The value of the resistance FV / I itself was several times (n times) in the case of no catalyst. Since the film thickness is thinner than that when a catalyst is used, assuming that this value is 1 / n times, the electrical resistivity is the same.

As described above, according to the film forming apparatus according to the present embodiment, the sp ³ / sp ² structure ratio is 0.32 to 0.5, and the half width of the G band peak in Raman spectroscopy is A DLC film of 70 cm ⁻¹ or less is obtained.

The electrical resistivity of the DLC film is 0.2 to 2.0 × 10 ⁻³ [Ωm].

  The film thickness can be 1 to 10 μm.

  Although the invention made by the present inventor has been specifically described based on the embodiments, the embodiments disclosed herein are illustrative in all respects and are not limited to the disclosed technology. Should not be considered. That is, the technical scope of the present invention should not be construed restrictively based on the description in the above embodiment, but should be construed according to the description of the scope of claims. All modifications that fall within the scope of the claims and the equivalent technology are included.

For example, by controlling the ratio of acetone / hydrogen supplied by the hot water bath temperature of acetone, the carbon sp ³ / sp ² ratio and band gap value of the DLC film to be formed without changing the processing temperature in the reactor It is possible to control characteristics such as an electric resistance value.

DESCRIPTION OF SYMBOLS 10 ... Film-forming apparatus 12 ... Gas supply source 14 ... Flow path 16 ... Control part 18 ... Acetone gas supply source 20 ... Supply source 22 ... Gas control part 24 ... Temperature control part 26 ... Electric furnace 30 ... Deposition object 30f ... Deposition target surface (surface)
34 ... DLC film (diamond-like carbon film)
60 ... Hot water bath container 61 ... Container 63 ... Acetone 70, 71 ... Supply pipe 128 ... Core tube 200 ... Acetone collector 201 ... Container 202 ... Liquid nitrogen 203 ... Pipe 203a ... U-shaped pipe RG ... Gas for film formation

Claims (16)

A flow path for arranging a film formation target for forming a diamond-like carbon film and flowing a gas other than the film formation gas and the film formation gas;
A carrier gas supply source for supplying a carrier gas containing hydrogen gas, nitrogen gas or argon gas to the flow path at a predetermined flow rate;
A carbon source gas supply source for supplying a carbon source consisting of a gas of a ketone body, an alcohol, or a carboxylic acid to the flow path at a predetermined flow rate;
A gas control unit for controlling a gas flow rate from the carrier gas supply source and the carbon source gas supply source to the flow path;
A heating section for increasing the temperature of the flow path;
A temperature control unit that controls the heating unit such that the temperature in the flow path becomes a predetermined temperature,
The gas control unit controls the carrier gas to be supplied from the carrier gas supply source to the flow path until the flow path reaches the film formation temperature, and when the flow path reaches the film formation temperature. The film-forming gas is controlled to be supplied at a predetermined flow rate from the carrier gas supply source and the hydrocarbon gas supply source so that the carbon source is contained at a predetermined concentration. Diamond-like carbon film deposition system.   2. The diamond-like carbon film according to claim 1, wherein the gas control unit controls the carrier gas supplied from the carrier gas supply source to be supplied to the flow path after the film formation is completed. Deposition device.   3. The diamond-like carbon film formation according to claim 1, wherein the gas control unit controls to change the type of the carrier gas before and after the film formation. apparatus.   4. The diamond-like carbon film forming apparatus according to claim 1, wherein the film forming temperature is 1000 to 1400 ° C. 5.   The molar ratio of the film forming gas other than the carbon source and the film forming gas is 0.18 to 0.30: 1.0. The diamond-like carbon film forming apparatus described in 1.   The diamond-like carbon film forming apparatus according to any one of claims 1 to 5, wherein the ketone body is acetone.   7. The diamond-like carbon film forming apparatus according to claim 1, wherein gas supply by the carrier gas supply source and the gas control unit is performed through bubbling. 8. .   The diamond-like carbon film forming apparatus according to any one of claims 1 to 7, wherein the film formation target is made of a predetermined ceramic or a predetermined metal. Arranging a film-forming target for forming a diamond-like carbon film in a flow path for flowing hydrogen gas;
Flowing the hydrogen gas through the flow path at a predetermined flow rate and raising the film formation target from room temperature to a predetermined temperature;
When the temperature reaches the predetermined temperature, a film forming gas containing any of a ketone body, an alcohol, or a carboxylic acid as a carbon source at a predetermined concentration flows in the flow path over a predetermined time using the hydrogen gas as a carrier gas. A process of
Holding the state at the predetermined temperature for a predetermined time. A method for forming a diamond-like carbon film, comprising:   The method for forming a diamond-like carbon film according to claim 9, wherein the ketone body as the carbon source is acetone.   The method for forming a diamond-like carbon film according to claim 9 or 10, wherein the film formation target is made of ceramic or metal.   The impurity removal is performed on the surface of the film formation target by the reducing action of the hydrogen gas by flowing the hydrogen gas before flowing the film forming gas. The method for forming a diamond-like carbon film according to any one of the above.   The method of forming a diamond-like carbon film according to any one of claims 9 to 12, wherein a catalyst made of a metal is applied to a surface of the film formation target.   The method of forming a diamond-like carbon film according to claim 13, wherein the catalyst made of the metal is made of ceramic.   The method for forming a diamond-like carbon film according to any one of claims 9 to 14, wherein the predetermined temperature is 1000 to 1400 ° C.   The unnecessary carbon remaining on the surface of the diamond-like carbon film on the deposition target is removed by flowing the hydrogen gas after the formation of the diamond-like carbon film. The method for forming a diamond-like carbon film according to any one of claims 9 to 15.