JPH11278989A - Carbon-based coating film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a carbon-based coating film capable of eliminating a steep change in the concentration of an element at an interface between the coating film and an intermediate layer to improve the adhesion of the coating film by adding an element except the carbon to at least one among a place near to a substrate and a place near to the surface in the carbon coating film. SOLUTION: This carbon-based coating film is obtained by attaching a substrate 8 to the upper surface of a substrate drum 9, evacuating a vacuum chamber 7, rotating the substrate drum 9, simultaneously supplying Ar gas from a discharge gas introduction pipe 5, supplying microwaves from a microwave generator 1, irradiating the surface of the substrate 8 with the Ar plasma formed in a plasma-generating chamber 4, supplying CH4 gas from a reaction gas-introducing pipe 11, decomposing the CH4 gas by the action of the plasma, irradiating the surface of the substrate with the generated carbon in the state of highly reactive carbon ions or neutral active carbon, charging a high frequency electric power to a sputtering source 12 from a high frequency electric source 13, irradiating the surface of the substrate 8 with sputtering particles containing an additive element such as Si, N, F, B or O and simultaneously charging a high frequency electric power to form a region for mixing the additive element.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carbon-based film formed on a substrate, and more particularly to a surface modification such as a thin-film magnetic head, a compressor component, an electric shaver blade, a surface acoustic wave device, and screen printing. Related to masks for office automation (OA) equipment, protective films such as squeegees, insulating films, etc., as well as carbon-based coatings applied to mechanical, chemical and electronic components requiring abrasion and corrosion resistance. .

[0002]

2. Description of the Related Art Carbon-based coatings are highly expected as coating materials and the like because of their excellent hardness, insulating properties, chemical stability and the like.

For example, according to JP-A-1-317197, when a diamond thin film (coating) is formed on a substrate, if the diamond thin film (coating) is formed directly on the substrate, depending on the type of the substrate, Separation occurs at the interface between the substrate and the diamond thin film (coat) due to the internal stress of the diamond thin film (coat).

[0004] Therefore, in order to reduce peeling, an intermediate layer of silicon or the like is interposed between the substrate and the diamond thin film (coating), thereby improving the adhesion of the diamond thin film (coating) to the substrate. Peeling was reduced.

[0005]

However, the intermediate layer generally has poor mechanical properties such as hardness, does not contribute to the improvement of the wear resistance of the substrate surface, and does not contribute to a large external force by the carbon-based material. Peeling between the coating / intermediate layer or destruction of the intermediate layer itself occurred.

Furthermore, when a film is further formed on the carbon-based film, it does not contribute to improving the adhesion between the film and the carbon-based film.

[0007]

Means for Solving the Problems The carbon-based coating of the present invention comprises:
A coating formed on a substrate, wherein an element other than carbon is added to at least one of the vicinity of the substrate and the vicinity of the surface in the coating.

The concentration of the element has a gradient in the thickness direction of the coating.

The concentration gradient of the element is on the substrate side of the coating,
Alternatively, it is characterized by being higher on the surface side.

[0010] It is characterized in that the concentration gradient of the element changes in steps.

[0011] The element is characterized in that the concentration gradient of the element changes continuously.

[0012] The element is characterized in that it contains at least one element of Si, N, F, B and O.

It is characterized in that the concentration of the element is 50% or less.

[0014] The film is characterized in that the film thickness is 200 ° or less.

[0015] The carbon-based coating is an amorphous or crystalline carbon-based coating.

[0016] The present invention is characterized in that it is a sliding material in which the carbon-based coating is formed on a sliding portion.

The carbon-based coating is formed on a slider surface of a thin-film magnetic head.

The carbon-based coating is on the top of the thin-film magnetic head;
It is used for a lower gap insulating layer, an upper layer, a lower protective layer, or a separation layer.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS.

In the embodiments described below, unless otherwise specified, the additive element in the additive element mixed region is Si.

FIG. 1 is a schematic structural view of an apparatus for forming a carbon-based film according to the present invention.

As shown in FIG. 1, a plasma generation chamber (4) and a reaction chamber in which a substrate (8) is to be installed are formed inside a vacuum chamber (7). The microwave generator (1) is connected via a waveguide (2). A microwave introduction window (3) is provided at the connection between the waveguide (2) and the plasma generation chamber (4). A discharge gas introduction pipe (5) for introducing a discharge gas such as argon (Ar) into the plasma generation chamber (4) is connected to the plasma generation chamber (4). Further, a plasma magnetic field generator (6) is provided so as to surround the plasma generation chamber (4).

In a reaction chamber in the vacuum chamber (7), a substrate drum (9) is installed, and a reaction gas introduction pipe (1) is provided.
1) is connected. A high frequency power supply (10) is connected to the substrate drum (9).

A sputtering source (12) equipped with a target for adding an element to the film, and a sputtering source (12)
A high-frequency power supply (13) for supplying high-frequency power to the vehicle is provided.

Hereinafter, a method of forming an amorphous carbon-based film on a Si substrate using the apparatus shown in FIG. 1 will be described. <First Embodiment> First, a substrate (8) is mounted on a substrate drum (9), and the inside of a vacuum chamber (7) is set to 10 ^-5.
Exhaust to 10 ^-7 Torr. Next, the substrate drum is set to 8 to 10
While continuously rotating at rpm, the following steps A and B
Execute Step A: Formation of “added element mixed region” Ar gas is supplied at 9.5 × 10 ⁻⁴ Torr from the discharge gas introduction pipe (5), and 2.45 GHz, 1
By supplying a 00 W microwave, Ar plasma formed in the plasma generation chamber (4) is emitted to the surface of the substrate (8). CH ₄ gas is supplied from the reaction gas introduction pipe (11). CH ₄ gas supplied from the reaction gas introduction pipe (11)
The carbon is decomposed by the action of the plasma, and the resulting carbon becomes highly reactive ions or a neutral active state and is emitted to the surface of the substrate (8).

At the same time, the sputter source (12) is operated by supplying a high frequency power of 13.56 MHz and 200 W from the high frequency power supply (13) to the sputter source (12). Thereby, sputtered particles mainly containing the additional element in the film are emitted to the surface of the substrate (8). At the same time, high-frequency power having a frequency of 13.56 MHz is supplied from the high-frequency power supply (10) so that the self-bias voltage generated on the substrate becomes -50V.

The “added element mixed region” is formed by the process of step A described above.

Further, by increasing the rotation speed of the substrate drum, an element-added region in which the added elements are substantially uniformly dispersed is formed.

Further reducing the partial pressure of CH ₄ gas over time,
Alternatively, the structure of a carbon-based coating film in which the concentration of the additional element in the film increases or decreases in the film thickness direction by increasing the film thickness can be obtained. Step B: Formation of “Carbon-Rich Region” Ar gas is supplied at 5.7 × 10 ⁻⁴ Torr from the discharge gas inlet tube (5), and 2.45 GHz, 1 GHz is supplied from the microwave generator (1).
A microwave of 00 W is supplied to emit Ar plasma formed in the plasma generation chamber (4) to the surface of the substrate (8). 7.6 × 10 ^-4 Torr of CH ₄ gas was supplied from the reaction gas introduction pipe (11).
Supply by CH ₄ supplied from the reaction gas introduction pipe (11)
The gas is decomposed by the action of the plasma, and the resulting carbon becomes highly reactive ions or a neutral active state and is emitted to the surface of the substrate (8).

At the same time, high-frequency power having a frequency of 13.56 MHz is supplied from the high-frequency power supply (10) so that the self-bias voltage generated on the substrate becomes -50V. The “carbon-rich region” is formed by the process of step B described above.

In the carbon-rich region, the diffusion of the additional element due to the diffusion effect from the additional element mixed region or the implantation effect due to the kinetic energy of ions when forming the additional element mixed region formed subsequently to the carbon-rich region. It may contain a constituent element of the region.

Through the steps A and B described above, as shown in FIG. 2A, a film composed of the additive element mixed region and the carbon-rich region is formed. 2 and the step A, as shown in FIG. 2 (b), a film composed of the additive element mixed region, the carbon rich region, and the additive element mixed region is formed. At this time, a film as shown in FIG. 3 is formed through the process of Step A, Step B or Step A, and at this time, the Si concentration in the film continuously changes. <Example 1> In Example 1, a film composed of the additive element mixed region and the carbon-rich region was formed on the substrate (8) by performing the steps A and B described above. Specifically, on the Si substrate, in the order of Step A and Step B, the element-added region 200 mm on the substrate side and the total film thickness 1000 mm
And At this time, the gas partial pressure of CH ₄ with respect to the film thickness is:
It was changed as shown in FIG.

FIG. 5 shows the measured values of the Si concentration (%) and the Vickers hardness (Hv) with respect to the CH4 gas partial pressure in the additive element mixed region actually formed in step A. However, the rotation speed of the substrate drum was set at about 10 rpm.

As is apparent from FIG.
% Or higher, a ceramic level high hardness of 2000 Hv or more can be obtained at a CH ₄ gas partial pressure or more. Therefore, in order to ensure the wear resistance of the additive element mixed region, the additive element concentration is preferably 50% or less. More preferably,
30% or less. <Embodiment 2> In Embodiment 2, by performing the above-described steps A, B, and A, the substrate (8) is formed with the additive element mixed region, the carbon-rich region, and the additive element mixed region. A coating was formed. In particular,
Step A, step B, and step A were performed in the order of step A, step B, and step A to provide a substrate-side element-added region 200 mm, a surface-side element-added region 50 mm, and a total film thickness of 1000 mm. At this time, the gas partial pressure of CH ₄ with respect to the film thickness was changed as shown in FIG. <Comparative Example 1> As a comparative example, a Si intermediate layer (film thickness 2) was formed on a Si substrate.
00Å), and a carbon-based thin film (film thickness 80
0 °, formed in step B of the present application).

Here, the coatings formed in Examples 1 and 2 and the coating formed in Comparative Example 1 were subjected to a wear resistance test. Specifically, the coefficient of friction when the surface of the coating film was slid with an alumina ball to which a load of 500 g was applied was measured, and the results are shown in FIG. The vertical axis of FIG. 6 represents the relative friction coefficient, and the horizontal axis represents the relative number of slides when the number of slides in which the coating is worn and the friction coefficient increases in Comparative Example 1 is set to 100. is there.

From these results, it can be seen that, in comparison with Comparative Example 1, Example 1,
In Example 2, the number of times of sliding until the coefficient of friction increased was improved by about 30% and 25%, respectively. In Example 2, a stable coefficient of friction was obtained from the beginning of sliding.

As an additional element in the film, in addition to Si, N
Experiments show that almost the same results can be obtained when using BN (for target), F (using Teflon for target), B (using BN for target), and O (using SiO for target). I have confirmed. <Second Embodiment> Next, an embodiment relating to application of a carbon-based coating to a sliding member will be described.

Although the present embodiment is the same in that steps A and B described in the first embodiment are used, the present embodiment is different from the first embodiment in that the substrate ( the type of 8) Al ₂ O ₃ -TiC (AlTiC)
Is used as the slider of the MR thin-film magnetic head having the main base.

In this embodiment, the formation conditions are the same as those described in the first embodiment. <Example _3> Al ₂ O 3 -TiC steps on the slider surface of the MR thin-film magnetic head whose main base A, and is formed in the order of steps B, and the thickness of the added elements mixed region from the slider surface 20 ° and the total film thickness was 80 °. Example 4 Steps A, B, and A were formed in the order of step A, step B, and step A on the slider surface of an MR thin-film magnetic head having Al ₂ O ₃ —TiC as a main underlayer. The thickness was set to 20 °, the thickness of the additive element mixed region on the surface side was set to 10 °, and the total thickness was set to 80 °. <Comparative Example 2> As Comparative Example 2, Si was formed on the slider surface of an MR thin film magnetic head having Al ₂ O ₃ —TiC as a main underlayer.
An intermediate layer (film thickness: 20 °) was formed, and a carbon-based thin film (film thickness: 80 °, formed in Step B of the present application) was further formed on the intermediate layer.

Here, the coatings of Examples 3 and 4 and the coating of Comparative Example 2 were respectively formed on the slider surface of the MR thin-film magnetic head, and a wear resistance test was conducted between the head and the hard disk. Was. Here, a carbon-based protective layer formed by sputtering or the like is formed on the surface of the hard disk in contact with the MR thin-film magnetic head.

FIG. 7 shows the results of measuring the coefficient of friction between the MR thin-film magnetic head and the hard disk. The vertical axis in FIG. 7 represents the relative friction coefficient, and the horizontal axis represents the relative number of slides when the sliding time at which the coating is worn and the friction coefficient increases in Comparative Example 2 is set to 100. .

From the results, it can be seen that Example 3 and Comparative Example 2
In the fourth embodiment, the sliding time until the friction coefficient increases is improved by about 30% in both cases. Further, in Example 4, it can be seen that a stable coefficient of friction was obtained from the beginning of sliding.

Since the added element mixed region on the film surface in Example 4 is lower in material hardness than the carbon rich region, it is considered that the wear resistance is inferior to the surface composed of the carbon rich region in Example 3. However, it is considered that the wear amount in the initial stage of the sliding is reduced due to the effect of the reduction of the friction coefficient in the initial stage of the sliding, and as a result, the number of times of the sliding is equalized.

Therefore, in Example 3, the complexity of the process or the amount of wear of the mating sliding material (hard disk) was taken into consideration.
Alternatively, any one of 4 and 4 may be selected.

The present invention eliminates the need for an intermediate layer, which was conventionally required when forming a carbon-based protective film on the MR thin film head slider surface, so that the MR film head slider surface which is indispensable for increasing the recording density of a hard disk drive. It is possible to make the upper protective film thinner. <The upper part of the thin film magnetic head, the lower gap insulating layer, the upper part,
Embodiment relating to application of lower protective layer or separation layer> FIG.
1 shows an example of a schematic cross-sectional view of a thin-film magnetic head.

In the upper, lower gap insulating layer, upper and lower protective layers or separation layers of the thin film magnetic head shown in FIG. 8, the layer (coating) formed as a base or on the upper part is mainly made of NiFe or the like. Metal.

The carbon-based film of the present invention is applied to any one of the upper, lower gap insulating layer, lower protective layer, and separation layer of the thin-film magnetic head by the steps A, B, and A. It is desirable to form the carbon-based coating of the present invention by the steps A and B in the upper protective layer. <Embodiment 5> As Embodiment 5, the 1
After forming a film on the NiFe thin film of μm in the order of Step A and Step B (substrate side element addition region 50Å, total thickness 400Å),
Further, a 1 μm NiFe layer was formed on the film. <Example 6> As Example 6, Ni formed on a Si substrate was used.
After the steps A, B, and A are formed on the Fe thin film in the order of (the substrate-side element-added region 50 °, the surface-side element-added region 50 °, the total film thickness 400 °), a NiFe layer is further formed on the film.
1 μm was formed. Comparative Example 3 As Comparative Example 3, Ni formed on a Si substrate was used.
After forming a Si intermediate layer (thickness of 50 mm) on the Fe thin film, forming a carbon-based thin film (thickness of 350 mm, formed in step B),
An iFe layer was formed at 1 μm.

Here, the indentation test was performed on Example 5, Example 6, and Comparative Example 3. The number of peelings occurring when a Vickers indenter was pushed into the 50 places on the sample surfaces of Example 5, Example 6, and Comparative Example 3 with a load of 300 g was investigated. The results are shown in Table 1.

[0049]

[Table 1]

From this test result, the number of occurrences of peeling is reduced in each of Examples 5 and 6 as compared with Comparative Example 3, and the effect of improving the adhesion of the element-added regions near the substrate interface and near the surface is recognized. .

The substrate in the present invention is not particularly limited, and the term “substrate” used in the present specification includes a film on which a base layer or the like is formed. Therefore, for example, one including an adhesive layer formed between the substrate and the substrate is also included.

[0052]

As is clear from the above description, according to the present invention, a structure in which an element is added near the substrate interface and the concentration is further inclined, instead of the conventional intermediate layer only for improving the adhesion. This eliminates the conventional abrupt change in element concentration at the interface between the coating and the intermediate layer, which causes peeling, and improves the adhesion by substantially eliminating the interface.

Since the element-added region is basically a part of the carbon-based coating having excellent mechanical properties such as hardness and abrasion resistance, unlike the conventional intermediate layer, the element-added region improves the abrasion resistance of the substrate surface. Can also contribute.

Further, by forming the element-added region also in the vicinity of the surface of the carbon-based film, the adhesion between the film subsequently formed on the carbon-based film and the carbon-based film is improved, and the surface of the carbon-based film is improved. It is possible to avoid an increase in the friction coefficient at the beginning of sliding due to the adsorbed dirt.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a film forming apparatus according to the present invention.

FIG. 2A is a schematic sectional view of a film formed by the steps A and B, and FIG. 2B is a step A, a step B and a step A; FIG. 2 is a schematic cross-sectional view of a coating formed by the above method.

FIG. 3 shows Si in a vertical sectional direction of a film formed by steps A, B, and A.
It is a figure showing the change of density.

FIG. 4 is a diagram showing a change in partial pressure of CH ₄ gas used in steps A, B and A;

FIG. 5 is a diagram showing a relationship among a partial pressure of CH ₄ gas, a Si concentration, and Vickers hardness in a region where an additive element is mixed in a film formed in the process of Step A.

FIG. 6 is a diagram showing the results of a wear resistance test of Example 1, Example 2, and Comparative Example 1.

FIG. 7 is a diagram showing the results of a wear resistance test of Example 3, Example 4, and Comparative Example 2.

FIG. 8 is a schematic sectional view of a thin-film magnetic head.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Microwave generator 2 ... Waveguide 3 ... Microwave introduction window 4 ... Plasma generation chamber 5 ... Discharge gas introduction pipe 6 ... Plasma magnetic field generator 7 ... Vacuum chamber 8 ... Substrate 9 ... Substrate drum 10 ... High frequency power supply 11 ... Reaction gas introduction pipe 12 ... Sputter source 13 ... High frequency power supply for sputter source

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Hisaki Tarui 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd.

Claims (12)

[Claims] 1. A carbon-based coating film formed on a substrate, wherein an element other than carbon is added to at least one of the vicinity of the substrate and the vicinity of the surface in the coating film. . 2. The carbon-based coating according to claim 1, wherein the concentration of the element has a gradient in a thickness direction of the coating. 3. The carbon-based coating according to claim 2, wherein the concentration gradient of the element is higher on the substrate side or the surface side of the coating. 4. The carbon-based coating according to claim 2, wherein the concentration gradient of the element changes in steps. 5. The carbon-based coating according to claim 2, wherein the concentration gradient of the element changes continuously. 6. The method according to claim 1, wherein the element is at least Si, N, F, B, O
The carbon-based coating according to any one of claims 1 to 5, further comprising at least one element selected from the group consisting of: 7. The carbon-based coating according to claim 1, wherein the concentration of the element is 50% or less. 8. The carbon-based coating according to claim 1, wherein the thickness of the coating is 200 ° or less. 9. The carbon-based coating according to claim 1, wherein said carbon-based coating is an amorphous or crystalline carbon-based coating.
The carbon-based coating according to any one of the above. 10. A sliding material comprising the carbon-based coating according to claim 1 formed on a sliding portion. 11. A thin-film magnetic head, wherein the carbon-based coating according to claim 1 is formed on a slider surface of the thin-film magnetic head. 12. The thin film magnetic head according to claim 1, wherein the carbon-based coating is used for an upper portion, a lower gap insulating layer, an upper portion, a lower protective layer, or a separation layer. Thin film magnetic head.