JPH05124875A - Article having diamond-like thin-film protective film - Google Patents

Abstract

PURPOSE:To improve adhesiveness by forming an intermediate layer consisting of a mixture composed of Si and C and a diamond-like thin film on the surface of a specific base body selected from an alloy contg. one kind among Co, Ni and Fe, ceramics and glass. CONSTITUTION:A high vacuum is maintained in a chamber 31. Gases for forming the intermediate layer consisting of the org. Si compd. and the C-contg. compd. or gases for forming the diamond-like thin film and a carrier gas are introduced from a supply port 35 into the chamber. On the other hand, a potential difference Vd is impressed to a hot cathode filament 34 and an anode 36 to form an electric discharge to thermally crack the gases for film formation and to bring the gases into collision against the thermions from the cathode filament 34 so as to form cations and electrones. A potential difference Va is then impressed to a base body 32 consisting of a grid 33 and glass, etc., to attract the cations and to bring the cations into collision against the base body 32, by which the reaction to form the film is effected. The intermediate layer which has 0.02 to 3.0mum film thickness, is amorphous and has the concn. of the Si decreasing from the base body 32 side toward the diamond thin film side is formed and in succession, the diamond-like thin film is then formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for improving the adhesiveness or bondability of a diamond-like thin film to an article substrate having poor adhesion.

[0002]

2. Description of the Related Art Diamond-like thin films produced by the vapor phase method have high hardness, excellent wear resistance, durability, chemical resistance, corrosion resistance, etc., and can be attached to articles of any shape. One or more of the above are useful as a protective film for the necessary articles. There are various types of methods for producing a diamond-like thin film by the vapor phase method (for example, refer to various methods in "Surface Chemistry" Vol. 5, No. 108 (1984), pages 108-115). The diamond-like thin film is coated on the surface of an article to be protected in an arbitrary shape, and is widely used as a protective film for corrosion resistance, abrasion resistance and the like.

The diamond-like thin film can be firmly bonded to a substrate such as silicon, but the bonding force to the substrate is weak depending on the type of article, and there is a problem that it is easily peeled off from the substrate by the action of external force. Therefore, the effect cannot be sufficiently exerted in an application in which corrosion resistance, abrasion resistance, etc. are required as a protective coating. In particular, Fe-based metals or alloys (for example, mild steel (STC), stainless steel, hardened steel (SKD, SKS), etc.), alloys of metals such as Co and Ni, glass, ceramics, etc. have a binding force to a diamond-like thin film. Known to be weak. The base material mainly composed of iron has the highest industrial value such as a mechanical member and a sliding member, and has a wide range of uses such as being used for a sliding portion such as a thermal head in glass and ceramics. Therefore, it is important to improve the adhesion of the diamond-like thin film formed on the surface of these substrates to the substrate.

It is disclosed in JP-A-60-200898 and JP-A-60-2046 that a substrate is pretreated to improve its adhesiveness.
No. 95, No. 61-174376 and the like.

[0005]

In Japanese Patent Laid-Open No. 60-200898, when a Co-WC alloy is used as a substrate and a diamond-like thin film is applied as a high hardness film on the surface of the substrate, glow discharge is directly applied to the surface of the substrate beforehand. However, since the acceleration voltage is not applied, the etching efficiency is not sufficient from the viewpoint of improving the adhesiveness, and the adhesiveness intended by the present invention cannot be sufficiently improved. Similarly to the above-mentioned technique, JP-A-60-204695 also introduces Ar gas into the decompression chamber and applies a voltage between the positive and negative electrodes to generate plasma to act on the substrate in order to improve the film forming rate. Since the ion concentration of plasma is low, the etching effect is low from the viewpoint of improving the adhesiveness. Japanese Unexamined Patent Publication No. 61-174376 describes that a substrate is treated with a plasma gas to improve the adhesion of the substrate, and then the substrate is oxidized to form an oxide film. However, in plasma, positive ions must first pass through a grid of positive potential by diffusion, and a sufficient amount of positive ions necessary for film formation cannot reach the substrate, resulting in an inefficient method. Therefore, it is impossible to form a film having a sufficiently high adhesive force between the substrate and the diamond-like thin film by the conventionally known technique. Further, Japanese Patent Application Laid-Open No. 3-80190 describes a method of accelerating ions to bombard the surface of a substrate, which is superior to the above-mentioned methods but does not necessarily provide sufficient binding force.

Therefore, the present inventors have filed Japanese Patent Application No. 3-14267.
In No. 8, it was proposed to use Mo as an intermediate layer to improve the adhesiveness. It has been found that this intermediate layer produces excellent cohesive strength. When the present inventors tried other materials as the intermediate layer, the same or more effects as those described in the same application were obtained. Therefore, an object of the present invention is to provide an article provided with a diamond-like thin film which has a large bonding force or adhesive force with respect to a substrate, is resistant to peeling and has improved durability.

[0007]

The present invention is made of Co, Ni,
An intermediate layer made of an amorphous mixture of silicon and carbon and a diamond-like thin film on the surface of a substrate selected from the group consisting of alloys containing at least one of Fe, ceramics and glass and having a poor affinity with the diamond-like thin film. There is provided an article having a protective film formed in order. It should be noted that the molding or processing mold is the subject of another patent application and is therefore excluded from the present invention.

The material of the intermediate layer used in the present invention is the following 3
It is an amorphous mixture derived from the gas of the seed material.
Here, the gas is a gas of a low molecular weight compound containing the following 1 and both carbon and silicon, a mixed gas of 2 and 3, 1 and 2, 1 and 3, or 1 and 2 and 3 low molecular weight substances. Is. Since the diamond-like thin film is supported, the intermediate layer also needs to have sufficient hardness. (1) Organosilicon compound-methylsilane CH ₃ SiH
₃ , dimethylsilane (CH ₃ ) ₂ SiH ₂ , trimethylsilane (CH ₃ ) ₃ SiH, tetramethylsilane Si
(CH ₃ ) ₄ . (2) Silicon compound-silane SiH ₄ , disilane Si ₂
H _6, tetrafluoride silicon SiF _4. (3) carbon compounds - methane CH _4, ethane C ₂ H _6, propylene C ₃ H _8, ethylene C ₂ H _4, acetylene C ₂
H ₂ .

A method for forming the intermediate layer is disclosed in Japanese Patent Application No.
The biased plasma CVD method described in JP-A-14480 or the ionization vapor deposition method described in JP-A-58-174507 and JP-A-1-234396 can be used. Here, after forming the intermediate layer, it is desirable to shift to the next diamond-like thin film forming step without exposing the film to the air. Therefore, it is necessary to use the same vacuum chamber. Incidentally, preferably prior to this step,
The substrate is placed in a vacuum chamber of a film forming apparatus, a bombarding gas such as Ar is introduced into the vacuum chamber, and ionization is performed by an ionizing means including a hot cathode filament and an anticathode surrounding the hot cathode filament. A pre-process of forming a flow and accelerating it by a grid having a lower potential than the anticathode to bombard the surface of the substrate to activate it may be adopted.

The resulting intermediate layer is amorphous rather than crystalline. As will be compared later, it produces a larger cohesive force than a crystalline intermediate layer. In addition, it is desirable that the intermediate layer first has a large amount of silicon component, and as the film is formed, the silicon component is reduced and the carbon component is increased. As a result, the binding force can be further improved. The thickness of the intermediate layer is 0.02
3 μm is preferable, and more preferably 0.05 to 0.5.
μm. If it is too thin, there is no effect, and if it is too thick, the effect saturates.

In the formation of the intermediate layer by the ionization deposition method and the bias application CVD method, the above-mentioned single or mixed gas is used. Further, in the formation of a diamond-like thin film by the ionization deposition method, a hydrocarbon raw material gas or a raw material gas capable of producing hydrocarbons by decomposition or reaction (here, hydrocarbon is a saturated hydrocarbon such as methane, ethane, propane,
There are unsaturated hydrocarbons such as ethylene, propylene, and acetylene, and the source gas that can decompose to produce hydrocarbons is alcohols such as methyl alcohol and ethyl alcohol,
There are ketones such as acetone and methyl ethyl ketone, and the raw material gas that reacts to generate a hydrocarbon gas includes carbon monoxide, a mixed gas of carbon dioxide and hydrogen, and the like. The raw material may contain a rare gas such as helium, neon, or argon, or at least one of hydrogen, oxygen, nitrogen, water, carbon monoxide, carbon dioxide, etc.) between the hot cathode filament and the cathode. It is a method of forming a diamond-like thin film by ionizing by means such as arc discharge, ionization by thermionic emission between the cathode hot filament and the anticathode to form an ion flow, and accelerating this flow with an electric field and directing it toward the substrate. Yes, for details, see JP-A-58-174507.
And JP-A-1-234396.

FIG. 1 shows a preferred example of a film forming apparatus for the intermediate layer and the diamond-like thin film. In the figure, 30 is a vacuum container, 31
Is a chamber, which is connected to the exhaust system 38 and is 10 ⁻⁶ T
It is pulled to a high vacuum up to about orr. Reference numeral 32 denotes an electrode provided on the back surface of the substrate S and kept at the negative potential Va. A mask 42 having a window that is close to or in contact with the surface of the substrate S to regulate the shape of the diamond-like thin film is provided. This mask may be in contact with the substrate, but is separated as much as possible in order to reduce the thickness of the peripheral portion of the film and reduce cracks. A grid 33 is provided with the same potential Va as that of the substrate and is used for accelerating hydrocarbon ions in the film forming process. This grid 33 uses a grid having an appropriately determined porosity (area of holes per unit area) and hole density (number of holes per unit length) in order to enhance the continuity of the film and smooth the surface. Alternatively, it may have a means for vibrating in the in-plane direction. Reference numeral 34 denotes a hot cathode filament maintained at a negative potential Vd, which is heated by a current If from an AC power source to generate thermoelectrons. Reference numeral 35 is a source gas supply port, 37 is a gas supply passage, and 37 'is a plasma excitation chamber. An anode 36 is arranged surrounding the filament 34. This anode is in this case grounded but has a positive voltage Vd for the filament,
A positive potential Va is applied to the electrode 32 and the grid 33. An electromagnetic coil 39 that surrounds the filament 34, the anode 36, and the supply port 35 and that is excited by the current Ic from the power source Vc to generate a magnetic field for confining the ionized gas is arranged. Therefore, If, V
The film quality can be changed by adjusting a, Vd, and the current Ic of the coil.

When forming a film, the inside of the chamber 31 is set to 10 ^-6.
High vacuum up to Torr, and operating the valve of the gas supply passage 37 at a predetermined flow rate to form a gas for forming an intermediate layer or a gas for forming a diamond film, or a mixed gas of hydrogen and hydrogen, or Ar and He, if necessary. While introducing a carrier gas such as Ne from each supply port 35, the exhaust system 38 is adjusted to a predetermined gas pressure, for example, 10 ^-1 Torr. On the other hand, an alternating current If is passed through the hot cathode filaments 34 to heat them, and a potential difference Vd between the filaments 34 and the anode 36.
Is applied to form a discharge. The raw material gas supplied from the supply port 35 is thermally decomposed and collides with the thermoelectrons from the filament to generate positive ions and electrons. This electron collides with another pyrolytic particle. By repeating such a phenomenon under the confinement action of the magnetic field of the electromagnetic coil, the raw material gas becomes positive ions of the thermal decomposition material. The positive ions are attracted by the negative potential Va applied to the electrode 32 and the grid 36, are accelerated toward the substrate S, and collide with the substrate to cause a film formation reaction to form an intermediate layer or a diamond-like thin film. Regarding the conditions such as the potential, current and temperature of each part, refer to the above-mentioned patent publications in addition to the conditions described above.

As a method for forming the intermediate layer, the biased plasma CVD method shown in FIG. 2 can be used in addition to the above-mentioned ionization vapor deposition method. A film forming apparatus for the intermediate layer will be exemplified. 51
Is a chamber, 52 is an RF power source, 53 is a substrate electrode, 54
Is an RF electrode, 55 is a substrate to be protected, 56 is an electrode 53,
A variable DC bias power source for applying a bias voltage between 54, 57 is a source gas introduction port, and 58 is an exhaust port. The dimension between the electrodes is, for example, about 4 cm. The bias voltage may be, for example, -50V to -5KV. For example, RF power of 50 W to 2 kW and reaction time of 10 to 60 minutes can be used. The Vickers hardness of the amorphous mixture of silicon and carbon in the intermediate layer can be 300 to 2500 Kg / mm ² . The present invention will be exemplified below.

[0015]

[Explanation of Examples]

Example 1 Using Si ₂ H ₆ and CH ₄ as raw materials and using the ionization vapor deposition apparatus of FIG. 1, article substrates shown in Table 1 (quartz glass (SUPRASIL (trade name): Shin-Etsu Quartz Co., Ltd.) and SKD11 steel sheet). An intermediate layer was formed on top of this, and then a diamond-like thin film was formed. That is, filament 3
Reference numeral 4 was a coil shape having a width of 3 mm and a gap 8 mm with the electrode 36 surrounding the coil. The grid 33 is 5 mm /
Vibrated at a speed of minutes. If = 25A, Va = -500
An intermediate layer was obtained under the conditions of V, Vd = -30V and magnetic flux density of 400 G of the electromagnetic coil. No peak was detected anywhere when measured by X-ray, and the intermediate layer was amorphous. Next, the raw material was changed to CH ₄ , and If = 25A, Va = −900V,
A diamond-like thin film with a film thickness of 3.0 μm was obtained under the conditions of Vd = −30 V and magnetic flux density of 400 G of the electromagnetic coil.

Example 2 Si ₂ H ₆ and CH ₄ were used as raw materials and the bias voltage plasma CVD apparatus shown in FIG. 2 was used.
50 V, flow rate 60 (cm ³ min ^-1 ), total pressure 0.025
The intermediate layer was formed under the conditions of Torr, RF power of 500 W, reaction time of 10 minutes, substrate temperature of 200 ° C., and electrode distance of 4.0 cm. No peak was detected anywhere when measured by X-ray, and the intermediate layer was amorphous. Then, according to Example 1, a diamond film was formed by the ionization vapor deposition method.

Example 3 Using (CH ₃ ) SiH as a raw material, an intermediate layer and a diamond thin film were sequentially formed in the same manner as in Example 1. The intermediate layer was amorphous. Example 4

Using (CH ₃ ) SiH as a raw material, an intermediate layer and a diamond thin film were sequentially formed in the same manner as in Example 2. The intermediate layer was amorphous.

Comparative Example 1 A SiC intermediate layer was formed by a plasma CVD method using SiCl ₄ , CH ₄ , H ₂ , and Ar as raw materials, and then a diamond-like thin film was formed according to Example 1. X
The intermediate layer was crystalline as measured by a line.

Comparative Example 2 An intermediate layer was formed by RF sputtering using a target of Si ₃ N ₄ in Ar gas, and then a diamond-like thin film was formed according to Example 1. The intermediate layer was amorphous as measured by X-ray.

The characteristics of the protective film of the resulting article with a protective film are as shown in Table 1. However, the evaluations of the adhesion force and the scratch force were as follows. Adhesion is 1 cm square, length 1
A 0 cm prism was adhered to a diamond-like thin film with an epoxy resin, pulled by a tensile tester (Tensilon-trade name), peeled off, and measured. The scratch force is Rhesca
It was measured with a CSR-02 tester manufactured by the same company. However, all the values are relative values with the value in the first row (ionization vapor deposition method) of Table 1 being 1.0.

[0022]

[Table 1]

[0023]

According to the present invention, as compared with Comparative Examples 1 and 2 which consist of an amorphous mixture of silicon and carbon, a crystalline intermediate layer of silicon and carbon, and an intermediate layer other than silicon and carbon are adhered even if they are amorphous. The intervening intermediate layer, without improved force, allowed the diamond-like thin film to be applied to article substrates that would normally be difficult to bond.

[Brief description of drawings]

FIG. 1 shows an outline of an ionization vapor deposition apparatus used in the present invention.

FIG. 2 is a biased ionization CVD used in the present invention.
An outline of the vapor deposition device is shown.

[Explanation of symbols]

32 substrate 33 grid 34 hot filament 35 gas inlet 36 anode 39 electromagnetic coil 51 chamber 52 RF power source 53 substrate electrode 54 RF electrode 55 substrate to be protected 56 DC bias power source for applying bias voltage between electrodes 53 and 57 gas source Inlet port 58 Exhaust port

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[Procedure amendment]

[Submission date] August 7, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0023

[Correction method] Change

[Correction content]

[0023]

According to the present invention , the diamond is formed by interposing the intermediate layer made of an amorphous mixture of silicon and carbon.
Can be applied to article substrates that are normally difficult to bond.
It became possible. As in Comparative Examples 1 and 2 , in a crystalline intermediate layer of silicon and carbon and an intermediate layer other than silicon and carbon, the adhesion is not improved even if it is amorphous.

Claims (4)

[Claims] 1. An amorphous mixture of silicon and carbon on the surface of a substrate selected from the group consisting of alloys containing at least one of Co, Ni and Fe, ceramics and glass and having a poor affinity for diamond-like thin films. An article having an intermediate layer consisting of and a protective film in which a diamond-like thin film is sequentially formed. 2. The article having a protective film according to claim 1, wherein the intermediate layer is formed by a biased plasma CVD method or an ionization vapor deposition method. 3. The article having a protective film according to claim 1, wherein the thickness of the intermediate layer is 0.02 to 3.0 μm. 4. The silicon concentration of the intermediate layer decreases from the substrate side toward the diamond-like film side, and the carbon concentration has a reverse gradient, which is characterized in that. An article having a protective film of.