JP2012087330A - Dlc film deposition method and dlc film deposition apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a DLC (Diamond Like Carbon) film deposition method and a DLC film deposition apparatus, capable of reducing the film deposition cost of a DLC by using inexpensive raw material gas.SOLUTION: A Sabatier reaction chamber 20 is stored inside a processing chamber 3. A catalyst is stored in the Sabatier reaction chamber 20. Carbon dioxide gas and hydrogen gas is filled in the reaction part 22, and when the temperature in the reaction part 22 is high, the Sabatier reaction is executed in the reaction part 22 to generate methane gas and steam. The methane gas generated in the Sabatier reaction chamber 20 is supplied into the processing chamber 3, and used as raw material gas for DLC film deposition.

Description

  The present invention relates to a DLC film forming method and a DLC film forming apparatus for forming a DLC film.

  For example, in order to reduce the fuel consumption of automobiles, DLC (Diamond) having low friction and wear resistance (high hardness) is applied to at least a part of the surface of a base material used as various sliding members mounted on automobiles. (Like Carbon) film may be covered (for example, Patent Document 1).

JP-A-5-117856

The DLC film is formed by using, for example, a plasma CVD method. In this case, a plasma CVD apparatus is used, and a hydrocarbon gas such as methane is used as one of the source gases. The source gas is turned into plasma in the processing chamber of the plasma CVD apparatus, and hydrocarbons synthesized in a vapor phase are deposited on the surface of the base material, whereby DLC is formed on the surface of the base material.
In an apparatus for depositing DLC, a raw material gas is prepared by being filled in a container such as a gas cylinder. This source gas is supplied into the processing chamber through the introduction pipe. Hydrocarbon gas is relatively expensive. A large amount of hydrocarbon gas is required for the film formation of DLC, which may increase the film formation cost of DLC.

  Accordingly, an object of the present invention is to provide a DLC film forming method and a DLC film forming apparatus capable of reducing the DLC film forming cost by using an inexpensive source gas.

The invention according to claim 1 for achieving the above object is a DLC film forming method for forming DLC, wherein carbon dioxide and hydrogen are subjected to a Sabatier reaction (first reaction) to generate methane. A DLC film forming method including a methane generation step and a DLC film formation step for forming a DLC film by converting the methane generated in the methane generation step into plasma.
According to the method of the present invention, methane is generated using carbon dioxide as a raw material gas, and a DLC film is formed using the generated methane. Therefore, DLC can be obtained using inexpensive carbon dioxide, and it is not necessary to supply methane to the apparatus separately. Thereby, the film formation cost of DLC can be reduced.

  The invention according to claim 2 for achieving the above object is a DLC film forming apparatus (1) for forming a DLC film, which can accommodate a substrate to be film-formed ( 3), methane supply means (20, 26, 31, 25, 29) for supplying methane to the processing chamber, and methane supplied to the processing chamber by the methane supply means is converted into plasma in the processing chamber. A DLC film forming apparatus including a Sabatier reaction chamber (20) for generating methane by causing a Sabatier reaction between carbon dioxide and hydrogen.

The numbers in parentheses represent corresponding components in the embodiments described later, but are not intended to limit the scope of the claims to the embodiments.
According to this structure, there exists an effect similar to the effect described in relation to Claim 1.
In this case, as shown in claim 3, at least a part of the Sabatier reaction chamber may be accommodated in the processing chamber. According to this configuration, the Sabatier reaction chamber is accommodated in the processing chamber. When plasma is generated in the processing chamber, the temperature in the processing chamber increases accordingly, and the temperature in the Sabatier reaction chamber also increases as the temperature in the processing chamber increases. Therefore, the heat required for the Sabatier reaction between carbon dioxide and hydrogen can be obtained from the processing chamber (inside atmosphere). Therefore, it is not necessary to separately provide a heat source for heating the Sabatier reaction chamber in the Sabatier reaction chamber. Therefore, it is possible to form a DLC film using a DLC film forming apparatus having a simpler structure, thereby further reducing the DLC film forming cost.

It is sectional drawing which shows typically the structure of the plasma CVD apparatus with which the DLC film-forming apparatus concerning one Embodiment of this invention is applied. It is a block diagram which shows the electrical structure of the plasma CVD apparatus shown in FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a cross-sectional view schematically showing a configuration of a plasma CVD apparatus 1 to which a DLC film forming apparatus according to an embodiment of the present invention is applied.
The plasma CVD apparatus 1 includes a processing chamber 3 surrounded by a partition wall 2, a base 5 that holds a substrate 200 in the processing chamber 3, and a gas introduction pipe 6 for introducing a source gas into the processing chamber 3. An exhaust system 7 for evacuating the inside of the processing chamber 3 and a plasma power source 8 for generating a direct-current pulse voltage for converting the gas introduced into the processing chamber 3 into plasma are provided. The plasma CVD apparatus 1 is an apparatus for performing a direct current plasma chemical vapor deposition (Direct Current Plasma Chemical Vapor Deposition) method.

  The base 5 includes a support plate 9 in a horizontal posture and a support shaft 10 that extends in the vertical direction and supports the support plate 9. In this embodiment, a three-stage type in which three support plates 9 are arranged in the vertical direction is adopted as the base 5. The base 5 is entirely formed using a conductive material such as copper. A negative electrode of a plasma power source 8 is connected to the base 5. The substrate 200 is placed on the support plate 9.

  Further, the partition wall 2 of the processing chamber 3 is formed using a conductive material such as stainless steel. A positive electrode of a plasma power source 8 is connected to the partition wall 2. The partition wall 2 is grounded. The partition wall 2 and the base 5 are insulated by an insulating member 11. Therefore, the partition wall 2 is kept at the ground potential. When the plasma power supply 8 is turned on and a DC pulse voltage is generated, a potential difference is generated between the partition wall 2 and the base 5.

A Sabatier reaction chamber 20 is accommodated in the processing chamber 3. The periphery of the Sabatier reaction chamber 20 is surrounded by the partition wall 2. Carbon dioxide gas (CO ₂ ) is supplied from the carbon dioxide gas supply source to the Sabatier reaction chamber 20, and hydrogen gas (H ₂ ) is supplied from the hydrogen gas supply source to the Sabatier reaction chamber 20. It comes to be supplied. The Sabatier reaction chamber 20 includes a mixing unit 21 for mixing the supplied carbon dioxide gas and hydrogen gas, and a reaction unit 22 for causing the Sabatier reaction of the carbon dioxide gas and hydrogen gas mixed in the mixing unit 21. I have. A catalyst is accommodated in the reaction unit 22. Examples of the catalyst include those in which ruthenium is supported on aluminum oxide, nickel, rhodium, and the like.

When the reaction unit 22 is filled with carbon dioxide gas and hydrogen gas and the temperature in the reaction unit 22 is high (for example, 300 to 350 ° C.), the reaction unit 22 has a Sabatier expressed by the following formula (1). The reaction (Sabatier first reaction) is performed. That is, methane gas (CH ₄ ) and water (H ₂ O. Here, water vapor) is generated in the reaction unit 22.
CO ₂ + 4H ₂ → 2H ₂ O + CH ₄ (1)
One end of an exhaust liquid pipe 23 for discharging methane gas and water vapor generated by the Sabatier reaction in the reaction unit 22 to the outside of the processing chamber 3 is connected to the Sabatie reaction chamber 20. The other end of the exhaust liquid pipe 23 penetrates the partition wall 2 and is exposed outside the processing chamber 3.

A gas-liquid separator 24 is interposed in the middle of the exhaust liquid pipe 23 outside the Sabatier reaction chamber 20. One end of a methane gas recovery pipe 26 for recovering methane gas is connected to the gas-liquid separator 24. The other end of the methane gas recovery pipe 26 is connected to a methane gas storage unit 31 for storing methane gas.
Since the outer wall of the exhaust pipe 23 is exposed to a normal temperature atmosphere outside the Sabatier reaction chamber 20, the water vapor flowing through the exhaust pipe 23 is condensed into water and flows in a mixed state with methane gas, which is a gas. . The methane gas separated by the gas-liquid separator 24 is guided to the methane gas storage unit 31 through the methane gas recovery pipe 26 and stored in the methane gas storage unit 31.

Further, the gas introduction pipe 6 extends in the horizontal direction above the base 5 in the processing chamber 3. A number of gas discharge holes 12 arranged along the longitudinal direction of the gas introduction pipe 6 are formed in a portion of the gas introduction pipe 6 facing the base 5. By discharging the source gas from the gas discharge hole 12, the source gas is introduced into the processing chamber 3.
A mixing unit 27 is connected to the gas introduction pipe 6 through a mixed gas valve 28. The mixing unit 27 is supplied with argon gas (Ar) from an argon gas supply source. The mixing unit 27 is supplied with hydrogen gas from a hydrogen gas supply source. Furthermore, a methane gas supply pipe 25 that supplies methane gas stored in the methane gas storage unit 31 is connected to the mixing unit 27. A methane gas valve 29 for opening and closing the methane gas supply pipe 25 is interposed in the middle of the methane gas supply pipe 25. That is, the methane gas generated in the Sabatier reaction chamber 20 is supplied to the mixing unit 27 by opening the methane gas valve 29.

The exhaust system 7 includes a first exhaust pipe 13 and a second exhaust pipe 14 that communicate with the processing chamber 3, a first on-off valve 15, a second on-off valve 16, a third on-off valve 19, a first pump 17, and a first pump 17. 2 pump 18.
A first opening / closing valve 15 and a first pump 17 are interposed in this order from the processing chamber 3 side in the middle of the first exhaust pipe 13. As the first pump 17, for example, a low vacuum pump such as an oil rotary vacuum pump (rotary pump) or a diaphragm vacuum pump is employed. The oil rotary vacuum pump is a positive displacement vacuum pump that reduces an airtight space and an ineffective space between components such as a rotor, a stator, and a sliding blade with oil. Examples of the oil rotary vacuum pump adopted as the first pump 17 include a rotary blade type oil rotary vacuum pump and a swing piston type vacuum pump.

  The tip of the second exhaust pipe 14 is connected between the first opening / closing valve 15 and the first pump 17 in the first exhaust pipe 13. A second opening / closing valve 16, a second pump 18, and a third opening / closing valve 19 are interposed in this order from the processing chamber 3 side in the middle of the second exhaust pipe 14. As the second pump 18, for example, a high vacuum pump such as a turbo molecular pump or an oil diffusion pump is employed.

  FIG. 2 is a block diagram showing an electrical configuration of the plasma CVD apparatus shown in FIG. The plasma CVD apparatus 1 includes a control device 30 having a configuration including a microcomputer. The control device 30 includes a plasma power source 8, a first opening / closing valve 15, a second opening / closing valve 16, a third opening / closing valve 19, a mixed gas valve 28, a methane gas valve 29, a first pump 17, a second pump 18, and the like. Connected as.

Next, an example of a film forming process for forming a DLC film (forming a DLC film) on the surface of the substrate 200 using the plasma CVD apparatus 1 will be described with reference to FIG.
First, after setting the base material 200 on the support plate 9 of the base 5 in the processing chamber 3, the processing chamber 3 is closed.
Next, the control device 30 drives the first pump 17 with the first, second and third on-off valves 15, 16, 19 closed, and then opens the first on-off valve 15 to open the inside of the processing chamber 3. Exhaust. When the inside of the processing chamber 3 is evacuated to a predetermined first low pressure by the first pump 17, the first opening / closing valve 15 is closed and the third opening / closing valve 19 is opened to drive the second pump 18, and then the second opening / closing is performed. By opening the valve 16, the inside of the processing chamber 3 is further exhausted by the first and second pumps 17 and 18.

  When the inside of the processing chamber 3 reaches a predetermined second low pressure (second low pressure <first low pressure), the control device 30 closes the second and third on-off valves 16 and 19 and stops the second pump 18. At the same time, the first opening / closing valve 15 is opened. Thereafter, exhaust is continued only by the first pump 17. Further, the control device 30 opens the mixed gas valve 28 to introduce argon gas and hydrogen gas into the processing chamber 3.

  Next, the control device 30 turns on the plasma power supply 8 and applies a negative DC pulse voltage (for example, −1000 V) to the base 5. Thereby, a potential difference is generated between the partition wall 2 and the base 5, and plasma is generated in the processing chamber 3. Due to the generation of the plasma, ions and radicals are generated from the source gas in the processing chamber 3, and the ions and radicals are struck against the surface of the base material 200 based on the potential difference. (Atomic level irregularities) are formed (pretreatment step). Further, by bombarding the surface of the substrate 200 with ions or radicals, foreign molecules adsorbed on the surface of the substrate 200 can be removed by sputtering, the surface can be activated, or the atomic arrangement can be modified ( Ion bombardment).

  In addition, the atmosphere in the processing chamber 3 becomes high temperature (300 to 350 ° C.) due to the generation of plasma, and the atmosphere in the Sabatier reaction chamber 20 accommodated in the processing chamber 3 is also a high temperature (300 to 350 ° C.). 350 ° C.). In addition, carbon dioxide gas and hydrogen gas are supplied to the mixing unit 21 of the Sabatier reaction chamber 20 from the start of the film forming process. The supply of carbon dioxide gas and hydrogen gas is continued until the film formation process is completed. Therefore, the Sabatier reaction in the reaction unit 22 is promoted, and methane gas and water vapor are generated in the reaction unit 22.

  The methane gas and water vapor flow while being cooled in the exhaust liquid pipe 23 and are supplied to the gas-liquid separator 24. The methane gas separated from the water is guided to the methane gas storage part 31 through the methane gas recovery path 26 and stored in the methane gas storage part 31. That is, after the temperature of the processing chamber 3 reaches a high temperature, methane gas is generated in the Sabatier reaction chamber 20, and the generated methane gas is stored in the methane gas storage unit 31.

  When a predetermined processing time elapses after the plasma power source 8 is turned on, the control device 30 turns off the plasma power source 8 and closes the mixed gas valve 28 to stop the supply of hydrogen gas and argon gas to the processing chamber 3. . Next, the control device 30 opens the methane gas gas valve 29 and the mixed gas valve 28 while maintaining the reduced pressure state in the processing chamber 3. Thereby, the methane gas stored in the methane gas storage unit 31, in other words, the methane gas generated in the reaction unit 22 is introduced into the processing chamber 3 together with the argon gas and the hydrogen gas.

  Next, the control device 30 turns on the plasma power source 8 to generate a potential difference between the partition wall 2 and the base 5, thereby generating plasma in the processing chamber 3. Due to the generation of the plasma, the hydrogen gas and methane gas in the processing chamber 3 are turned into plasma, and the vapor-phase synthesized hydrocarbon is deposited on the surface of the substrate 200. Thus, a DLC deposition film (DLC film) is formed on the surface of the substrate 200 (DLC is formed) (DLC film forming step).

Moreover, the atmosphere in the processing chamber 3 becomes high temperature (300 to 350 ° C.) due to generation of plasma,
The atmosphere in the Sabatier reaction chamber 20 accommodated in the processing chamber 3 is also at a high temperature (300 to 350 ° C.) that is about the same. Therefore, the Sabatier reaction in the reaction unit 22 of the Sabatier reaction chamber 20 is promoted, methane gas is generated in the reaction unit 22, and the generated methane gas is stored in the methane gas storage unit 31.

As described above, according to this embodiment, methane gas is generated using carbon dioxide gas as a raw material gas, and a DLC film is formed using the generated methane gas. Therefore, since DLC can be obtained using inexpensive carbon dioxide gas, it is not necessary to supply methane gas to the plasma CVD apparatus 1 separately. Thereby, the film formation cost of DLC can be reduced.
Further, the Sabatier reaction chamber 20 is accommodated in the processing chamber 3. When plasma is generated in the processing chamber 3, the temperature in the processing chamber 3 rises along with this, and the ambient temperature in the Sabatier reaction chamber 20 also rises as the temperature in the processing chamber 3 rises. Therefore, heat necessary for the Sabatier reaction between carbon dioxide gas and hydrogen gas can be obtained from the atmosphere in the processing chamber 3. Therefore, it is not necessary to separately provide a heat source for heating the Sabatie reaction chamber 20 in the Sabatier reaction chamber 20. Therefore, it is possible to form a DLC film using the plasma CVD apparatus 1 having a simpler structure, thereby further reducing the DLC film forming cost.

As mentioned above, although one Embodiment of this invention was described, this invention can also be implemented using another form.
For example, water separated from methane gas by the gas-liquid separator 24 may be reused as cooling water for cooling the exhaust liquid pipe 23.
Alternatively, water separated from the methane gas may be electrolyzed, and the hydrogen gas generated by the electrolysis may be supplied to the mixing unit 21 of the Sabatier reaction chamber 20 and used as a raw material gas for generating methane gas. Alternatively, hydrogen gas generated by electrolysis may be supplied to the mixing unit 27 and used as a source gas for DLC film formation.

Further, the configuration may be such that not all of the Sabatier reaction chamber 20 is accommodated in the processing chamber 3 but only a part of the Sabatier reaction chamber 20 is accommodated in the processing chamber 3. In this case, if at least the reaction unit 22 is surrounded by the partition wall 2, the atmospheric temperature in the reaction unit 22 can be increased as the atmospheric temperature in the processing chamber 3 increases.
Further, in the above-described processing steps, an intermediate layer covering the surface of the substrate 200 may be formed prior to the DLC film formation. In the case where the formation of the intermediate layer is performed by converting the inside of the processing chamber 3 into plasma, methane gas can be generated by causing the reaction unit 22 to perform a Sabatier reaction even when forming the intermediate layer.

Further, it is not necessary that all the methane gas used as the source gas for forming the DLC film is the methane gas generated in the reaction unit 22, and the methane gas generated in the reaction unit 22 and the methane gas from the methane gas supply source may be used in combination. it can.
In addition, the supply of hydrogen gas and carbon dioxide gas to the mixing unit 21 does not have to be performed throughout the entire process, and may be performed only during the previous process. It may be performed only for a period. Moreover, hydrogen gas and carbon dioxide gas may be supplied to the mixing unit 21 only when the amount of methane gas stored in the methane gas storage unit 31 is equal to or less than a predetermined amount.

Moreover, although the case where a DLC deposition layer to which no additive is added is formed on the surface of the base material 200 is described as an example, of course, Si (silicon), Fe (iron), Co (cobalt) ), At least one element among elements such as Ti (titanium) may be added. For example, when Si is added to DLC, an organic silicon compound gas such as tetramethylsilane gas (Si (CH ₃ ) ₄ ) or siloxane is used as a raw material gas together with hydrogen gas and methane gas during the DLC film forming process. Can be introduced in.

Further, the DLC film can be formed not by the direct-current pulse plasma CVD method but by using another plasma CVD method (direct-current plasma CVD method or high-frequency plasma CVD method). In this case, the plasma CVD apparatus 1 may be provided with a mechanism necessary for performing these plasma CVD methods by addition or change.
In addition, various design changes can be made within the scope of matters described in the claims.

DESCRIPTION OF SYMBOLS 1 ... Plasma CVD apparatus, 2 ... Partition, 3 ... Processing chamber, 5 ... Base, 8 ... Plasma power supply, 20 ... Sabatier reaction chamber, 25 ... Methane gas supply pipe, 26 ... Methane gas recovery pipe, 29 ... Methane gas valve, 31 ... Methane gas storage

Claims (3)

A DLC film forming method for forming a DLC film,
A methane gas generation step of generating methane gas by reacting carbon dioxide gas and hydrogen gas with a Sabatier reaction;
A DLC film forming method comprising: forming a DLC film by converting the methane gas generated in the methane gas generating step into plasma. A DLC film forming apparatus for forming a DLC film,
A processing chamber capable of accommodating a substrate to be deposited;
Methane gas supply means for supplying methane gas to the processing chamber;
Plasma generating means for converting the methane gas supplied to the processing chamber by the methane gas supplying means into plasma in the processing chamber,
The said methane gas supply means is a DLC film-forming apparatus containing the Sabatier reaction chamber which produces | generates methane gas by making Sabatier reaction of carbon dioxide gas and hydrogen gas. The DLC film forming apparatus according to claim 2, wherein at least a part of the Sabatier reaction chamber is accommodated in the processing chamber.

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