JPH08225924A - Formation of carbon-nitrogen compound-containing film - Google Patents

Abstract

PURPOSE: To provide a method for forming a carbon-nitrogen compound- containing film on a substrate capable of forming a film which is hardly reduced in hardness even having a high C/N composition ratio and is superior in adherence even irradiated with ion of comparatively small accelerating energy. CONSTITUTION: Carbon is vapor-deposited on the substrate S to form a film and the irradiations of the nitrogen ion and the inert gas ion are executed simultaneously or alternately on the substrate S to form a mixed layer Sm1 with the substrate S, and a carbon-nitrogen compound-containing film Sf, or preceding to this operation, the irradiation of the nitrogen ion and/or the inert gas ion are executed beforehand on the substrate S to form an ion pouring layer S1, mixed layer Sm2 and the carbon-nitrogen compound-containing film Sf.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to a substrate of an article such as a tool, a mold, a magnetic head or various sliding parts which is required to have abrasion resistance and sliding resistance in order to improve its performance. , A method for forming a carbon-nitrogen compound-containing film.

[0002]

2. Description of the Related Art Since carbon-nitrogen compounds have high hardness, in order to improve wear resistance and sliding resistance of articles such as tools, molds, magnetic heads and various sliding parts, these articles are used. Attempts have been made to form a film on the top. For example, according to Japanese Patent Application Laid-Open No. 5-287502, a carbon-nitrogen compound film can be formed on a substrate by simultaneously or alternately performing vapor deposition of carbon and irradiation of nitrogen ions on the substrate under a predetermined vacuum degree. It is disclosed. According to this method, a carbon-nitrogen compound film can be formed at a relatively low temperature,
By the nitrogen ion irradiation, a mixed layer of the constituent atoms of the substrate and the film constituent atoms is formed in the surface layer portion of the substrate at the initial stage of film formation, so that good film adhesion can be obtained.

[0003]

However, in the method according to the above-mentioned Japanese Patent Laid-Open No. 5-287502, the number of carbon (C) atoms and nitrogen (N) reaching the substrate is only because the ions to be irradiated are nitrogen ions. When the ratio of the number of atoms (C / N transport ratio) is large and the ratio of the number of carbon atoms contained in the film to the number of nitrogen atoms (C / N composition ratio) is large, carbon atoms that do not combine with nitrogen atoms are contained in the film. Therefore, the hardness of the film tends to decrease. For this reason, it is necessary to strictly control the C / N transport ratio, but it is difficult to control the C / N transport ratio because carbon is difficult to stabilize the vapor deposition rate. The composition ratio cannot be such that it does not include carbon atoms that do not combine with atoms.

Further, in the method according to the above publication, it is easier to form the mixed layer by increasing the acceleration energy of irradiation ions, but in this case, depending on the type of the substrate, ion irradiation may cause thermal and mechanical effects. Some of them are damaged, and the film adhesion cannot always be improved by forming the mixed layer. Therefore, the present invention is a method for forming a carbon-nitrogen compound-containing film on a film formation substrate, and when the C / N composition ratio of the formed film is large, in other words, carbon atoms that do not combine with nitrogen atoms are removed. A method for forming a carbon-nitrogen compound-containing film, in which the hardness of the film does not easily decrease even when the composition ratio is such that the film is formed, and the film can be formed with good adhesion even when ion irradiation is performed with relatively small acceleration energy. The challenge is to provide.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted repeated studies to solve the above problems and found the following facts. As in the film forming method taught in Japanese Patent Laid-Open No. 287502/1993, a carbon-nitrogen compound-containing film is formed on a substrate on which a film is to be formed by using a combination of vapor deposition of carbon and irradiation of ions containing nitrogen ions. When an inert gas ion is irradiated together with nitrogen ions to form a diamond, the carbon atoms are highly excited by collision between the irradiated ions and the vapor-deposited carbon atoms and a diamond-like or iC (eye carbon) high hardness crystal. Since the structure is formed, the hardness of the formed film does not decrease even when the C / N composition ratio of the formed film is large. Further, the mixed layer was easily formed and the film adhesion was improved as compared with the case of irradiating only nitrogen ions.

Based on the above findings, the present invention forms a carbon-nitrogen compound-containing film on a substrate to be deposited by simultaneously or alternately irradiating with nitrogen ions and inert gas ions. A method for forming a carbon-nitrogen compound-containing film is provided. The “irradiation” of ions used in the present specification includes the case where ions are implanted into the surface portion of the substrate along with the irradiation of ions.

In the method of the present invention, the carbon is vapor-deposited on the substrate by a vacuum vapor deposition method in which carbon is heated and vaporized by an electron beam, a resistance, a laser, a high frequency or the like, or a means such as an ion beam, a magnetron or a high frequency. Can be carried out by a sputter vapor deposition method. Nitrogen (N ₂ ) gas and ammonia (NH ₂ ) are used as a raw material gas for generating nitrogen ions by ion irradiation in the method of the present invention.
₃ ) Gas etc. are considered.

Examples of the inert gas ions in the ion irradiation include helium (He) ions, neon (Ne) ions, argon (Ar) ions, krypton (Kr) ions, xenon (Xe) ions, and the like.
Further, as a source gas for generating these ions, helium gas, neon gas, argon gas, krypton gas, xenon gas or the like is used, respectively.

Further, it is considered that the ion acceleration energy in the ion irradiation is set to 0.1 keV or more and 40 keV or less. When the ion acceleration energy is less than 0.1 keV, the film adhesion is poor because the mixed layer of both the substrate and the film is not sufficiently formed at the interface, and when it is more than 40 keV, the substrate is thermally and mechanically damaged. It becomes large, which is not preferable.

In the ion irradiation, the ratio of the number of nitrogen (N) ions reaching the substrate to the number of inert gas (I) ions (N / I transport ratio) may be 0.1 or more and 20 or less. Conceivable. If the N / I transport ratio is less than 0.1, the formed film is not sufficiently nitrided, and if it is more than 20, the action of the inert gas ions becomes insufficient, which is not preferable. N /
The I transport ratio can be controlled by adjusting the flow rate ratio of the nitrogen gas and the inert gas introduced into the ion source.

In the method of the present invention, it is considered that the ratio of the number of vapor-deposited carbon (C) atoms and the number of ions (i) reaching the substrate (C / i transport ratio) is 0.1 or more and 40 or less. C
When the / i transport ratio is less than 0.1, the film thickness of the film formed due to the sputtering action of the irradiation ions becomes too small. On the other hand, if it is larger than 40, vapor-deposited carbon atoms are hard to be highly excited by the irradiation ions, and as a result, it becomes difficult to form a highly hard crystal structure of carbon in the formed film and the hardness of the film is lowered.

The C / i transport ratio can be controlled by monitoring the deposition amount of carbon with a film thickness monitor and monitoring the number of irradiated ions with an ion current measuring device. In the method of the present invention, it is conceivable to irradiate the film-forming substrate with nitrogen ions and / or inert gas ions prior to the formation of the carbon-nitrogen compound-containing film. As a result, the surface of the substrate is cleaned, and in the case of irradiating with nitrogen ions, the surface portion of the substrate is nitrided in addition to this, and the adhesion with the carbon-nitrogen compound-containing film formed outside is further improved. To do.

It is considered that the ion acceleration energy in this ion irradiation is set to 0.1 keV or more and 40 keV or less. Further, it is considered that the ion irradiation amount is set to 1 × 10 ¹³ pieces / cm ² or more and 1 × 10 ¹⁸ pieces / cm ² or less.
If the ion acceleration energy is less than 0.1 keV, or if the ion irradiation dose is less than 1 × 10 ¹³ ions / cm ² , the cleaning or nitriding of the substrate surface is insufficient and the adhesion of the film formed on the outside thereof Cannot be improved sufficiently. Further, if the ion acceleration energy is larger than 40 keV, or if the ion irradiation amount is larger than 1 × 10 ¹⁸ ions / cm ² , thermal and mechanical damage to the substrate becomes large, which is not preferable.

In the method of the present invention, the type of ion source used for ion irradiation is not particularly limited, and, for example, a Kauffman type, a bucket type or the like can be considered. Further, the ion incident angle on the substrate is not particularly limited, and the ion irradiation may be performed while rotating the substrate. Further, for a substrate for which thermal damage must be sufficiently avoided, film formation (and ion irradiation) can be performed while cooling the substrate.

The material of the substrate is not particularly limited, and various ceramics, metals, polymers, etc. may be considered.

[0016]

According to the method for forming a carbon-nitrogen compound-containing film of the present invention, vapor-deposited carbon atoms are highly excited by irradiating inert gas ions in addition to nitrogen ions, and the carbon atoms have a diamond-like crystal structure or It becomes easy to form a high hardness crystal structure called iC. Therefore, even if the C / N composition ratio in the formed film is large, the hardness of the film is hard to be lowered, and the allowable range of the C / N composition ratio for forming a carbon-nitrogen compound-containing film having a desired hardness is Spreads and facilitates film formation.

By irradiating inert gas ions in addition to nitrogen ions, a mixed layer composed of the constituent atoms of both of them at the interface between the substrate and the film to be formed, as compared with the case of irradiating only nitrogen ions. Formation is facilitated. As a result, even if the ion acceleration energy is relatively small, it is possible to form the mixed layer having sufficient film adhesion, and even on a substrate that is easily thermally or mechanically damaged by ion irradiation. A carbon-nitrogen compound-containing film can be formed with good adhesion.

Further, prior to the formation of the carbon-nitrogen compound-containing film, when the film-forming substrate is irradiated with nitrogen ions and / or inert gas ions, the surface of the substrate is cleaned by sputtering with the irradiation ions and the outside thereof. The adhesion of the film formed on the substrate is further improved. In particular, when irradiating with nitrogen ions, in addition to cleaning the surface of the substrate, nitrogen ions are injected into the surface of the substrate to nitrid the portion, and the wettability with the carbon-nitrogen compound-containing film formed on the outside of the portion is nitrided. The improved adhesion and the improved conformity further improve the adhesion of the film to the substrate.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of an example of a film forming apparatus used for carrying out the method of the present invention. 2A is an enlarged cross-sectional view of a part of an example of a carbon-nitrogen compound-containing film-coated substrate obtained by carrying out the method of the present invention, and FIG. 2B is a carbon obtained by carrying out the method of the present invention. FIG. 7 is a partial enlarged cross-sectional view of another example of a nitrogen compound-containing film-coated substrate.

The apparatus shown in FIG. 1 has a vacuum container 1 in which a holder 2 for supporting a film-forming substrate S, a vaporization source 3 for evaporating carbon, and nitrogen are provided at a position facing the holder 2. Ion source 4 for irradiating ions and inert gas ions
Is installed. Further, a film thickness monitor 5 such as a crystal oscillator type film thickness monitor and an ion current measuring device 6 such as a Faraday cup are arranged near the substrate holder 2. Further, an exhaust device 7 is attached to the container 1 so that the inside of the container 1 can have a predetermined degree of vacuum.

In carrying out the method of the present invention using the apparatus described above, after the substrate S is supported by the holder 2, the inside of the vacuum container 1 is brought to a predetermined vacuum degree. Next, the carbon 3a is vacuum-deposited (or sputter-deposited) from the evaporation source 3 toward the substrate S.
At the same time or alternately, the ion source 4 irradiates the deposition surface with nitrogen ions 4a and inert gas ions 4b to form a carbon-nitrogen compound-containing film.

In the film forming operation, the acceleration energy during ion irradiation is set to 0.1 keV or more and 40 keV or less.
Further, the ratio of the number of nitrogen (N) ions reaching the substrate during ion irradiation and the number of inert gas (I) ions (N / I transport ratio) is 0.1 or more and 20 or less. Furthermore, the ratio of the number of vapor-deposited carbon (C) atoms and the number of ions (i) reaching the substrate (C / i transport ratio) is set to 0.1 or more and 40 or less.

As a result, the carbon-nitrogen compound-containing film Sf is formed on the substrate S as shown in FIG.
A mixed layer Sm1 of the both is formed at the interface between the film and the film Sf. Since the film Sf is formed by depositing carbon and irradiating inert gas ions in addition to nitrogen ions, it is easy for carbon atoms to form a high hardness crystal structure, and the C / N composition in the film Sf is high. Even if the ratio is large, the hardness does not easily decrease. Similarly, the irradiation of the inert gas ions facilitates the formation of the mixed layer Sm1, and even if the ion acceleration energy is reduced, the mixed layer Sm1 having sufficient adhesion to the substrate S can be obtained. Can be formed.

In another embodiment method, in forming the carbon-nitrogen compound-containing film Sf using the apparatus shown in FIG. 1, after the inside of the vacuum container 1 is set to a predetermined vacuum degree, the film Sf is formed. Prior to this, the substrate S is irradiated with nitrogen ions 4a or (and) inert gas ions 4b from the ion source 4.
At this time, the ion acceleration energy is 0.1 keV or more and 40 k
The ion irradiation dose is set to 1 × 10 ¹³ pieces / cm ² or more and 1 × 10 ¹⁸ pieces / cm ² or less.

In this way, the layer S1 in which nitrogen ions and / or inert gas ions are implanted into the surface of the substrate S is formed. Further, the film S is formed on the layer S1 by the same operation as described above.
f is formed. As a result, as shown in FIG.
A nitrogen ion or / and inert gas ion-implanted layer S1 is provided on the surface of the substrate S, a carbon-nitrogen compound-containing film Sf is formed outside the substrate S, and the carbon-nitrogen compound-containing film Sf is formed at the interface between the layer S1 and the film Sf. The mixed layer Sm2 is formed.

The surface of the substrate S is cleaned by the ion irradiation, and the layer S1 is nitrided when irradiated with nitrogen ions. Therefore, the wettability and the consistency of the layer S1, the mixed layer Sm2 and the film Sf are improved. Then, the adhesion of the film Sf to the substrate S is further improved. Next, a specific example of carrying out the method of the present invention using the apparatus shown in FIG. 1 and a carbon-nitrogen compound-containing film-coated substrate thus obtained will be described. Experimental Example 1 Using the apparatus shown in FIG. 1, stainless steel SUS3
The substrate S made of 04 is placed in the water-cooled substrate holder 2,
The inside of the vacuum container 1 was set to a vacuum degree of 1 × 10 ⁻⁶ Torr or less. Then, carbon pellets 3 with a purity of 99.9% (3N)
a was vaporized by using the electron beam evaporation source 3 to form a film on the substrate S. At the same time, nitrogen gas and argon (Ar) gas are supplied to the ion source 4 at a flow rate ratio of 1: 1 in the vacuum chamber 1.
It is introduced to a vacuum degree of × 10 ^-5 Torr and ionized, and the nitrogen ion 4a and the argon ion 4b are 5k.
The substrate S was irradiated vertically with an acceleration energy of eV.
At this time, the C / i transport ratio was 2. A bucket type ion source was used as the ion source.

A film thickness of about 5 is formed on the substrate S by the above film forming operation.
A carbon-nitrogen compound-containing film Sf having a thickness of 00 nm was formed. Along with this, the mixed layer Sm1 was formed at the interface with the substrate S. Experimental Example 2 Using the device shown in FIG. 1, stainless steel SUS3
The substrate S of No. 04 was placed on the substrate holder 2 and the inside of the vacuum container 1 was set to a vacuum degree of 1 × 10 ⁻⁶ Torr or less. Then, nitrogen gas is supplied to the ion source 4 in the container 1 at 5 × 10 ⁻⁵ To
It was introduced to a vacuum degree of rr and ionized, and the nitrogen ions 4a were irradiated at an acceleration energy of 2 keV perpendicularly to the substrate S at 1 × 10 ¹⁶ / cm ² . Thus, the nitrogen ion-implanted layer S1 was formed on the surface of the substrate S.

Then, in the same manner as in Experimental Example 1, the layer S of the substrate S is formed.
1. A carbon-nitrogen compound-containing film Sf having a film thickness of about 500 nm on
Was formed. Accordingly, the mixed layer S is formed at the interface with the layer S1.
m2 was formed. Experimental Example 3 In Experimental Example 2, as a gas used for ion irradiation prior to formation of the film Sf, argon gas was used instead of nitrogen gas, and otherwise the same as in Experimental Example 2 except that the layer S1, the film Sf, and the mixed layer Sm2 were formed. Formed. Comparative Example In Experimental Example 1, only nitrogen gas was used as the gas used for the ion irradiation for forming the film Sf, and the others were Experimental Example 1
A carbon-nitrogen compound-containing film having a thickness of about 500 nm was formed on the substrate S in the same manner as in.

Next, the hardness and film adhesion of each carbon-nitrogen compound-containing film obtained in Experimental Examples 1, 2, 3 and Comparative Example were evaluated. Hardness measures 10g Knoop hardness,
Adhesion was evaluated by measuring with a scratch tester.
The results are shown in the table below. Knoop hardness (kg / mm ² ) Adhesion (N) Experimental Example 1 3500 20 Experimental Example 2 4000 25 Experimental Example 3 3500 23 Comparative Example 1 3000 10 The membranes of Experimental Examples 1, 2 and 3 were compared with the membranes of Comparative Examples. And was excellent in both hardness and film adhesion. Further, the films according to Experimental Examples 2 and 3 were superior to the film according to Experimental Example 1 in film adhesion because the ion-implanted layer S1 was formed on the surface portion of the substrate S.

[0030]

According to the present invention, carbon-
A method for forming a nitrogen compound-containing film, wherein the hardness of the film is not easily lowered even when the C / N composition ratio of the film formed is large, and the adhesiveness is obtained even by ion irradiation with relatively small acceleration energy. It is possible to provide a method for forming a carbon-nitrogen compound-containing film capable of forming a good film.

Further, prior to the formation of the carbon-nitrogen compound-containing film, when the film-forming substrate is irradiated with nitrogen ions and / or inert gas ions, the carbon-nitrogen compound-containing film formed on the outside thereof. The adhesiveness of is further improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of an example of a film forming apparatus used for carrying out a method of the present invention.

FIG. 2 (A) is a partially enlarged sectional view of an example of a carbon-nitrogen compound-containing film-coated substrate obtained by carrying out the method of the present invention, and FIG. 2 (B) is obtained by carrying out the method of the present invention. FIG. 7 is an enlarged cross-sectional view of a part of another example of the carbon-nitrogen compound-containing film-coated substrate that is used.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vacuum container 2 Substrate holder 3 Evaporation source 3a Carbon 4 Ion source 4a Nitrogen ion 4b Inert gas ion 5 Film thickness monitor 6 Ion current measuring device 7 Exhaust device S Substrate S1 Ion implantation layer Sf Carbon-nitrogen compound containing film Sm1, Sm2 Mixed layer

Claims (2)

[Claims] 1. A carbon-nitrogen compound-containing film is formed on a substrate to be deposited by simultaneously or alternately irradiating with nitrogen ions and inert gas ions. -A method for forming a nitrogen compound-containing film. 2. The method for forming a carbon-nitrogen compound-containing film according to claim 1, wherein the film-forming substrate is irradiated with nitrogen ions and / or inert gas ions prior to the formation of the carbon-nitrogen compound-containing film. .