JPH11350140A - Device for forming thin film of carbon nitride and its method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an objective composition and structure of a film of carbon nitride and to improve an adhesive strength of the film of carbon nitride and a base material. SOLUTION: A base material 5 is located in a vacuum vessel 1. A plasma of a gaseous material which is nitrogen or contains nitrogen is supplied into the vacuum vessel 1 with a plasma generating device 6 and simultaneously a plasma of a gaseous material containing carbon is supplied into the vacuum vessel 1 with a plasma generating device 8. Subsequently a negative pulsative highly biased voltage is applied to the base material 5 with a pulsative high voltage source 11 to insert ion 14 into the base material 5 with high energy and to form a mixed layer of the film of carbon nitride and the base material. Afterwards a low negative DC biased voltage is applied to the base material 5 to insert ion 14 into the base material 5 with low energy and to form the film of carbon nitride film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of forming a carbon nitride film on a member requiring wear resistance, such as a sliding member such as a bearing or a slide of various rotary machines, a tool, or the like. The present invention relates to an apparatus and a method for manufacturing a thin film of a carbon film.

[0002]

2. Description of the Related Art Carbon nitride (Carbon Nitride; hereinafter abbreviated as CN) is predicted by calculation to have a hardness exceeding that of diamond when it has a β-C ₃ N ₄ structure. Also,
CN is expected to have excellent lubricity, thermal stability, and chemical stability even in compositions and structures other than the β-C ₃ N ₄ structure. Application to sliding members, tools, etc. is expected.

[0003] In order to synthesize a CN film, synthesis has been attempted by several methods. As the method, there are a sputtering method, a plasma CVD method, a laser evaporation method, and the like.
There is no confirmed example of synthesis of a CN film having a β-C ₃ N ₄ structure.

When attention is paid only to the composition ratio in the film, the stoichiometric composition ratio of β-C ₃ N ₄ (nitrogen: carbon = 3: 4) is obtained also in the carbon / nitrogen composition ratio in the CN film. Has not been
For all films, the composition is excess carbon and the nitrogen content is at most 3
It is 0%.

Further, the properties of the synthesized CN film are hardly clarified, and the CN film having a sufficient adhesion
Neither is the film synthesized.

Further, in the physical vapor deposition method such as the sputtering method and the laser vapor deposition method, the directivity of the supply material particles is strong, and it is applied to a sliding member such as a bearing or a slide of various rotary machines, or a three-dimensional complicated member such as a tool. Synthesis of CN films is very difficult.

[0007]

As described above, the desired composition and structure of the CN film cannot be obtained by the conventional manufacturing method, because the reactivity between carbon and nitrogen is very low. And that it is very difficult to control the composition and structure because β-C ₃ N ₄ is a non-equilibrium substance.

Further, since CN is a non-equilibrium substance, the internal stress accumulated in the film is large and sufficient adhesion cannot be obtained. Therefore, in order to synthesize β-C ₃ N ₄ , it is necessary to improve the reactivity between carbon and nitrogen and to improve the adhesion between the CN film and the substrate.

Further, it is necessary to be able to cope with the synthesis of the CN film on sliding members such as bearings and slides of various rotary machines, and three-dimensional complicated members such as tools.

In view of the above prior art, the present invention provides an apparatus and a method for producing a thin film of a carbon nitride film which can obtain a desired composition and structure of a CN film and which has high adhesion between the CN film and a substrate. The purpose is to provide.

[0011]

According to the present invention, there is provided a vacuum container, a substrate holder for holding a substrate in the vacuum container in an insulated state with respect to the vacuum container,
A first plasma generator that converts nitrogen or a material gas containing nitrogen into plasma and supplies the same into the vacuum vessel, a second plasma generator that converts a material gas containing carbon into plasma and supplies the same into the vacuum vessel, A pulse high-voltage power supply that applies a negative pulse-like high bias voltage with reference to the potential of the vacuum vessel, and a DC power supply that applies a low negative DC bias voltage with reference to the potential of the vacuum vessel. I do.

Further, according to the structure of the present invention, a plasma of a material gas containing nitrogen and a plasma of a material gas containing carbon are simultaneously supplied to a substrate placed in a vacuum space. Applying a pulsed high bias voltage to the substrate, accelerating the ions in the plasma with high energy to pull the ions into the substrate, forming a mixed layer of the carbon nitride film and the substrate, A low negative DC bias voltage is applied to the substrate to accelerate ions in the plasma with low energy to synthesize a carbon nitride film on the mixed layer.

In the configuration of the present invention, the negative pulsed high bias voltage is 5 kV or more and 200 kV or less,
The negative DC bias voltage is 0.1 kV or more and less than 5 kV.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An apparatus for manufacturing a thin film of a carbon nitride film according to an embodiment of the present invention and a method for manufacturing a thin film of a carbon nitride film using the apparatus will be described in detail with reference to the drawings.

FIG. 1 shows an apparatus for manufacturing a thin film of a carbon nitride film according to an embodiment of the present invention. As shown in FIG. 1, the present apparatus includes a vacuum vessel 1 evacuated by an evacuation apparatus 2. At the center of the vacuum vessel 1, a substrate holder 3 insulated from the vacuum vessel 1 by an insulator 4 is provided. The substrate 5 is attached to the substrate holder 3.

A pulse high voltage power supply 11 and a DC power supply 12 are selectively connected to the substrate holder 3 via a switch 13. That is, the switching of the switch 13 causes the base material holder 3 and the pulse high-voltage power supply 11
Is connected, a negative pulsed high bias voltage is applied to the substrate holder 3 and thus the substrate 5. Also,
When the substrate holder 3 and the DC power supply 12 are connected by the switching of the switch 13, a low negative DC bias voltage is applied to the substrate holder 3 and thus the substrate 5. Here, the polarity of the voltage is determined based on the potential of the vacuum vessel 1 as a reference (zero potential).

A first plasma generator 6 for converting nitrogen or a material gas containing nitrogen into plasma is provided above the vacuum vessel 1. This plasma generator 6
Converts the nitrogen or nitrogen-containing material gas introduced from the material gas inlet 7 into a plasma by means of electronic excitation by a hot filament, high-frequency discharge, or the like, and places a plasma of the nitrogen or nitrogen-containing material gas into the vacuum vessel 1. Supply.

Similarly, a second plasma generator 8 for converting a material gas containing carbon into plasma is provided above the vacuum vessel 1. The plasma generator 8 converts the material gas containing carbon introduced from the material gas inlet 9 into
Plasma is generated by electron excitation by a hot filament, high-frequency discharge, or the like, and plasma made of a material gas containing carbon is supplied into the vacuum chamber 1.

By the plasma generators 6 and 8, a plasma 10 composed of nitrogen or a material gas containing nitrogen and a material gas containing carbon is formed around the substrate 5.

Next, a method for synthesizing a CN film using the apparatus for manufacturing a thin film of a carbon nitride film shown in FIG. 1 will be described.

First, the substrate 5 made of a cube (for example, high speed tool steel) having a shape of 50 × 50 × 50 mm is subjected to ultrasonic cleaning with an organic solvent (for example, acetone). Installed in In this state, the evacuation device 2 is operated so that the pressure in the vacuum vessel 1 is 5 × 10
Pre-evacuate to ^-5 torr or less.

Next, nitrogen gas is introduced from the material gas inlet 7 of the plasma generator 6. A thermal filament for generating thermoelectrons is built in the plasma generator 6, and nitrogen gas is turned into plasma by electronic excitation. At the same time, ethane (C
₂ H ₆ ) gas is introduced. A thermal filament for generating thermoelectrons is also built in the plasma generator 8, and ethane gas is turned into plasma by electronic excitation. As a result, the substrate 5
Is generated in the vicinity of the plasma 10 using nitrogen and ethane as material gases.

At this time, the pressure in the vacuum vessel 1 is 5 × 10 ^-4.
At torr, a current of 50 A was passed through the hot filament. The flow rates of the nitrogen gas and the ethane gas are 20% by volume and 80% by volume, respectively.

Next, in this state, by switching the switch 13, the substrate holder 3 and the pulse high voltage power supply 11 are connected, and a negative pulsed high bias voltage is applied to the substrate holder 3 and thus the substrate 5. . By applying a negative pulsed high bias voltage to the substrate 5, the ions 14 generated in the plasma 10 are accelerated to high energy and are drawn into the substrate 5. At this time, the voltage of the pulse high voltage power supply 11 is 70 kV, the pulse width is 10 μs, and the repetition frequency is 5
00 Hz and processing time is 15 minutes. With this process,
A mixed layer of the carbon nitride film and the substrate 5 is formed on the surface of the substrate 5. This mixed layer has the effect of improving the adhesion of the carbon nitride film formed thereon.

Thereafter, the switching of the switch 13 connects the substrate holder 3 and the DC power supply 12, and applies a low negative DC bias voltage to the substrate holder 3 and thus to the substrate 5. Specifically, the DC power supply 12 sends the
Then, a negative DC bias voltage of 0.1 kV is applied to draw the ions 14 in the plasma 10 into the base material 5 with low energy to start the formation of the CN film. The film formation time is 60 minutes. By this processing, a CN film is formed on the mixed layer.

When the CN film produced by the above method was examined by photoelectron spectroscopy, a bond between carbon and nitrogen was recognized, and it was confirmed that the CN film was synthesized.

FIG. 2 shows the orientation of the substrate 5 with respect to the plasma source. Table 1 shows the surface A (the surface facing the plasma source) and the surface B
The graph shows the carbon / nitrogen composition ratio of the CN film formed on the plane and the C plane (the plane perpendicular to the A plane). All three surfaces showed almost the same carbon / nitrogen composition ratio of 1. Table 1 shows A, B, C
4 shows the thickness of the CN film on the surface. It shows almost the same film thickness.

[0028]

[Table 1]

Next, FIG. 3 shows a comparison of the adhesion of the CN film. The adhesive force was determined by a scratch test, and evaluated by the force when the CN film was peeled off from the substrate 5. A, B, and C planes showed almost the same value. For comparison, a value of a sample in which a negative DC bias voltage is applied without applying a pulsed high bias voltage and a CN film is formed is also shown.

From this result, it can be seen that the CN film formed by applying a pulsed high bias voltage has about three times the adhesion. In addition, CN prepared on A, B, and C surfaces
As a result of a sliding test between the film and the SUS ball, a result was obtained in which the coefficient of friction was lower than that of the high-speed tool steel as the base material and the wear width was small, and it was also confirmed that the wear resistance was excellent.

Incidentally, the negative pulsed high bias voltage is about 5
If it is not less than kV and not more than 200 kV, a mixed layer for improving the adhesion can be formed by adjusting the amount of each source gas introduced and the power introduced into the plasma generation source. This is because the negative pulsed high bias voltage is 5 kV.
In the following cases, a mixed layer sufficient to improve the adhesion cannot be formed, and the negative pulse-like high bias voltage is 200 kV.
When the voltage is V or more, ions are implanted deep inside the substrate, so that a mixed layer cannot be formed on the surface of the substrate. The reason why the pulse voltage is used is to prevent a breakdown between the substrate 5 and the vacuum vessel 1 which is likely to occur when a high voltage is applied.

If the negative DC bias voltage at the time of forming the CN film is 0.1 kV or more and less than 5 kV, similarly, by adjusting the amount of each source gas introduced and the power introduced to the plasma generation source, A CN film having a carbon / nitrogen composition ratio of 1 can be formed. This is because at less than 0.1 kV, nitrogen and carbon do not react, a CN film cannot be synthesized, and 5 kV
This is because, when the ratio exceeds 3, the formation of the mixed layer proceeds more than the film synthesis.

Nitrogen or a gas containing nitrogen, other than nitrogen gas, a mixed gas of nitrogen and a rare gas such as argon or neon, or ammonia may be used. As a gas containing carbon, methane, acetylene, benzene or the like may be used. Even with steam,
A CN film having the same performance can be synthesized.

As means for exciting the material gas, besides the electronic excitation by the hot filament, 13.56 MHz
Even if a high-frequency discharge using a high frequency or a microwave discharge using a microwave is used, a CN film having the same performance can be synthesized.

As described above, the method of the present invention in which the supply of low-energy nitrogen-containing ions and the supply of carbon-containing ions to the substrate at the same time is an effective means for non-equilibrium material synthesis. Can be improved in reactivity.

Further, by changing the supply amounts of the ions containing nitrogen and the ions containing carbon to the base material, the composition ratio of carbon / nitrogen in the CN film can be changed.

By increasing the energy of the supplied ions sufficiently, a kinetic energy forms a mixed layer of the CN film and the base material. By synthesizing the CN film at a low energy on this mixed layer, The adhesion between the film and the substrate can be improved.

[0038]

As described above in detail with the embodiments, in the invention, a vacuum container, a substrate holder for holding a substrate in the vacuum container in an insulated state with respect to the vacuum container, A first plasma generator for converting a material gas containing nitrogen into plasma and supplying the same into the vacuum container; a second plasma generator for converting a material gas containing carbon into plasma and supplying the same into the vacuum container; A pulse high-voltage power supply for applying a negative pulse-like high bias voltage based on the potential of the container and a DC power supply for applying a low negative DC bias voltage based on the potential of the vacuum container are provided.

In the present invention, the plasma of the material gas containing nitrogen and the plasma of the material gas containing carbon are simultaneously supplied to the base material arranged in the vacuum space,
First, a negative pulsed high bias voltage is applied to the base material, ions in the plasma are accelerated with high energy to attract the ions to the base material, and a mixed layer of the carbon nitride film and the base material is formed. Next, a configuration is adopted in which a low negative DC bias voltage is applied to the base material, ions in the plasma are accelerated with low energy, and a carbon nitride film is synthesized on the mixed layer.

As described above, in the present invention, by simultaneously supplying nitrogen-containing ions and carbon-containing ions, the reactivity between carbon and nitrogen is improved, and the synthesis of a carbon nitride film, which is a non-parallel substance, is rapidly performed. Can be done. Also, by changing the supply amounts of the ions containing nitrogen and the ions containing carbon, the composition ratio of carbon / nitrogen in the carbon nitride film can be changed.

Further, by initially applying a negative pulsed high bias voltage to the substrate to sufficiently increase the energy of the supplied ions, a mixed layer of the carbon nitride film and the substrate can be formed by its kinetic energy, Thereafter, by applying a low negative DC bias voltage to the base material, the carbon nitride film can be synthesized with low energy, so that the adhesion between the carbon nitride film and the base material can be improved.

Further, in the present invention, the negative pulsed high bias voltage is not less than 5 kV and not more than 200 kV, and the negative DC bias voltage is not less than 0.1 kV and less than 5 kV. Thus, a mixed layer can be formed on the surface of the base material, and the synthesis of the carbon nitride film proceeds favorably.

Finally, the apparatus and method for manufacturing a carbon nitride thin film according to the present invention enable the synthesis of a compound film of carbon and nitrogen, and have a high adhesion and a high wear resistance. Can be formed. It can also handle the formation of a carbon nitride film on three-dimensionally complex shaped members, and can be used for sliding members such as bearings and slides of various rotating machines, tools, etc. It can be used for the production of membranes.

[Brief description of the drawings]

FIG. 1 is a schematic structural view showing an apparatus for manufacturing a thin film of a carbon nitride film according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a direction of a substrate with respect to a plasma source.

FIG. 3 is a characteristic diagram showing a comparison of the adhesion of a carbon nitride film (CN film) by a scratch test.

[Description of sign]

 DESCRIPTION OF SYMBOLS 1 Vacuum container 2 Vacuum exhaust device 3 Substrate holder 4 Insulator 5 Substrate 6,8 Plasma generator 7,9 Material gas inlet 10 Plasma 11 Pulse high voltage power supply 12 DC power supply 13 Switch 14 Ion

Claims (4)

[Claims] 1. A vacuum container, a substrate holder for holding a substrate in the vacuum container in an insulated state with respect to the vacuum container, and converting nitrogen or a material gas containing nitrogen into a plasma and supplying it into the vacuum container A first plasma generator that converts a material gas containing carbon into a plasma and supplies the material gas into the vacuum vessel; and applying a negative pulsed high bias voltage based on the potential of the vacuum vessel. And a DC power supply for applying a negative DC bias voltage that is low with respect to the potential of the vacuum vessel. 2. The method according to claim 1, wherein the negative pulsed high bias voltage is 5
2. The apparatus according to claim 1, wherein the negative DC bias voltage is not less than 0.1 kV and less than 5 kV. 3. A plasma of a material gas containing nitrogen or a nitrogen-containing material gas and a plasma of a material gas containing carbon are simultaneously supplied to a base material placed in a vacuum space. Is applied to the substrate, ions in the plasma are accelerated with high energy to attract the ions to the substrate, forming a mixed layer of the carbon nitride film and the substrate, and then a low negative DC bias is applied. A method for producing a thin film of a carbon nitride film, comprising applying a voltage to the base material, accelerating ions in plasma with low energy, and synthesizing a carbon nitride film on the mixed layer. 4. The method according to claim 1, wherein the negative pulsed high bias voltage is 5
4. The method according to claim 3, wherein the negative DC bias voltage is 0.1 kV or more and less than 5 kV.