JP2002020870A - Method for depositing diamondlike carbon film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that hydrogen is left in a DLC film caused by the use of gaseous methane or gaseous ethylene as a gaseous starting material and to realize the coexistence of the superthinning and wear resistance of a DLC film by ECR plasma CVD. SOLUTION: Gaseous carbon oxide or gaseous nitrogen oxide is added to a gaseous starting material to deposit a film. Alternatively, film deposition is performed while the face of a substrate is irradiated with light with any wavelength in the region from far infrared radiation to ultraviolet radiation at the time of the film deposition. Alternatively, at least one kind of gas selected from gaseous oxygen, gaseous carbon oxide and gaseous nitrogen oxide is adsorbed on a substrate before DLC film deposition, and after that, film deposition is performed. By using any selected from those methods, the amount of hydrogen left in the DLC film is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a diamond-like carbon film, and more particularly to a slider for a thin film magnetic head slider applied to an apparatus for recording / reproducing a magnetic recording medium such as a magnetic disk drive (HDD). The present invention relates to a formation method suitable for forming a diamond-like carbon film on a moving surface (ABS surface) or the like.

[0002]

2. Description of the Related Art In recent years, the recording density of hard disk drives, which are external recording devices for computers, has rapidly increased, and it is certain that this tendency will increase in the future.

In response to this requirement, the magnetic head slider is required to have a very low flying height of 0.05 μm or less and a stable flying characteristic which does not change with the peripheral speed of the recording medium. Further, in the future, since high electromagnetic conversion characteristics are required even at a high recording density, it is strongly required that the flying height be further reduced and the vehicle be driven stably.

[0004] Among them, the electromagnetic conversion characteristics greatly depend on the distance between the head and the recording medium, which is called magnetic spacing. This distance can be divided into the flying height and the thickness of the protective film formed on the sliding surface. Actual flying height is
Even if the thickness is 0.05 μm or less, the thickness of the protective film is further added to achieve magnetic spacing. Therefore, the thickness of the protective film directly affects the magnetic spacing. When a reduction in the flying height is required, the protective film must be further thinned. Therefore, it is necessary to simultaneously realize the thinning and the protection of abrasion resistance and corrosion resistance.

Incidentally, a protective film actually put to practical use is a diamond-like carbon film (hereinafter abbreviated as a DLC film). The formation method includes a sputtering method, an ion plating method, a plasma CVD method, and an electron cyclotron resonance (ECR) plasma CVD. In each case, the film thickness is 5 nm or less. Further, as the film configuration, a two-layer film provided with a silicon underlayer for the purpose of improving the adhesive force is often used.

[0006] The sputtering method is a method in which a film is formed by directly sputtering a carbon-based target such as graphite. However, the hardness of the film is small and the wear resistance is not sufficient. Further, the ion plating method can obtain a film having high hardness, but there is a concern about productivity. Therefore, a film forming method using plasma is most used.

The present inventors have studied the formation of a thin film in which a DLC film having an underlayer provided on a slider sliding surface of a thin film magnetic head is formed by using an ECR plasma CVD method.
In particular, the properties of the DLC film are greatly affected by the ECR plasma CVD film forming conditions. Therefore, the DL with the highest hardness
The search and examination for obtaining the C film were performed.

As a result, the hardness of the film is 23 GPa when methane is used as a raw material gas, and the hardness is 30 GPa when ethylene gas is used. In addition, the hardness referred to here is determined by a method based on a nanoindentation test.

[0009]

However, in the above-mentioned conventional method, a higher recording density is required in the future, and a thinner layer is required.
In order to cope with the reduction of the flying height, merely changing the film forming conditions of ECR plasma CVD cannot expect a further increase in the hardness of the film. The reason is that methane gas and ethylene gas are used as raw material gas,
This is because hydrogen remains in the film. Accordingly, there has been a problem that it is difficult to achieve both ultra-thin film and abrasion resistance in response to a demand for higher density in the future.

An object of the present invention is to solve the above-mentioned problems and to provide a method for forming a DLC thin film which is both ultra-thin and abrasion-resistant and is suitable for application to the ABS of a magnetic head slider. Aim.

[0011]

In order to achieve the above object, a method for removing as much as possible the amount of hydrogen in the DLC film was studied. Then, during the film formation process, a third product is chemically generated to remove hydrogen from the film, and the substrate surface is made more excited than it is now, so that hydrogen atoms can easily escape from the DLC film. Inspired. As a result, they have found that the following method is extremely effective.

The method for forming a diamond-like carbon film of the present invention is a method for forming a diamond-like carbon film by plasma CVD, and has the following features.

The first method is characterized in that a film is formed by mixing at least a carbon monoxide gas or a carbon dioxide gas in a film forming material gas. According to this method, DLC
The amount of hydrogen inside can be reduced, and the hardness of the film is improved. As a result, abrasion resistance that can cope with ultra-thin film can be realized.

The second method is characterized in that a film is formed by mixing at least a nitrogen monoxide gas or a nitrogen dioxide gas with a film forming material gas. According to this method, the amount of hydrogen in the DLC can be reduced, and nitrogen atoms are taken into the DLC, thereby improving the effect of improving the hardness of the film.

According to the above-mentioned method, a high-hardness film can be easily obtained by merely mixing a predetermined gas with the raw material gas without modifying or newly adding an apparatus, thereby suppressing an increase in cost. it can.

The third method is characterized in that the film is formed while irradiating the substrate surface on which the film is to be formed with light selected from wavelengths ranging from far infrared rays to ultraviolet rays. According to this method,
The hydrogen existing on the surface of the sliding surface can be excited to remove hydrogen from the DLC film.

Further, the first or second method and the third method may be used in combination. Thereby, the molecules of the source gas are excited on the surface of the substrate, the reactivity is increased, and the hardness of the film is further improved.

In a fourth method, the surface of the substrate provided with the underlayer is
A method for forming a diamond-like carbon film by plasma CVD, wherein before forming the diamond-like carbon film,
After adsorbing at least one gas selected from oxygen gas, carbon monoxide gas, carbon dioxide gas, nitric oxide gas, and nitrogen dioxide on the substrate surface, a diamond-like carbon film is formed. I do. According to this method,
At least the amount of hydrogen in the initially formed layer can be reduced, and the effect of improving the hardness of the film can be obtained.

A good protective film can be obtained by forming a diamond-like carbon film on the slider sliding surface of a thin-film magnetic head using any one of the above-described methods for forming a diamond-like carbon film.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (Embodiment 1) FIG. 6 is a schematic diagram of an ECR plasma CVD apparatus used for carrying out the method for forming a diamond-like carbon film in Embodiment 1.

The main components of the ECR plasma CVD apparatus 2 shown in FIG. 6 are a plasma chamber 7, a microwave oscillator 4 for generating ECR plasma, a magnet 6 for excitation, and a waveguide 5 for guiding microwaves to the plasma chamber 7. Element. A substrate 10 on which a film is to be formed is held by a substrate holder 9, and a substrate bias is applied by a high-frequency power supply 3.

As the substrate 10, for example, a silicon wafer having a diameter of 6 inches is used. The film forming method is as follows. First, in a sputtering chamber (not shown) provided in the same apparatus, a silicon layer serving as an underlayer is formed to a thickness of about 2 nm, and then the substrate 10 is moved to the plasma chamber 7 in a vacuum. Next, a raw material gas is introduced through the gas inlet 1, and a plasma 8 is generated by the microwave oscillator 4. And magnet 6
A magnetic field is generated in the substrate 10 and the source gas plasma 8 is applied to the substrate 10.
Pull out to the side. At this time, the high frequency power supply 3 is connected to the substrate holder 9.
To apply a substrate bias.

The conditions for the film formation at this time are, for example, methane gas as a source gas, a gas pressure of 1.5 Pa, an input power of 200 W, and a high frequency bias power of 200 W. The total thickness of DLC and silicon is 100 nm.

In an example based on this embodiment,
During film formation, a carbon monoxide gas or a carbon dioxide gas was introduced into the plasma chamber 7 from the gas inlet 1. The amount of carbon monoxide gas or carbon dioxide gas is controlled by the flow rate,
The change in the characteristics of the formed film was examined by changing the ratio of the flow rate of the methane gas as the source gas to the flow rate.

FIG. 1 shows a result of forming a film by mixing a carbon monoxide gas or a carbon dioxide gas with a plasma of a methane gas as a raw material gas in the embodiment. The hardness is
This is a value measured by a nanoindentation test (the same applies hereinafter). The carbon dioxide gas amount is a ratio of the flow rate of the carbon monoxide gas or the carbon dioxide gas to the total flow rate of the mixed gas of the methane gas and the carbon monoxide gas or the carbon dioxide gas.

From FIG. 1, as the amount of carbon gas is increased,
It can be seen that the hardness of the DLC film increases. Both carbon monoxide gas and carbon dioxide gas are effective in increasing the hardness of the DLC film. In particular, when carbon monoxide gas is used, D
The hardness of the LC film is 2 in the case of the conventional example without the mixed gas.
The hardness increases from 3 GPa to 30 GPa. But,
When the amount of carbon dioxide gas is more than 4%, the hardness decreases.

As described above, according to the present embodiment, the hardness of the film is increased by mixing at least a carbon monoxide gas or a carbon dioxide gas with the plasma of the raw material gas methane gas to form a DLC film. Can be increased.

In this embodiment, methane gas is used as the raw material gas. However, similar results can be obtained by using other hydrocarbon gases such as ethylene gas.

(Embodiment 2) FIG. 2 is a graph showing the result of implementing the method of forming a diamond-like carbon film in Embodiment 2. The film forming method is the same as that in the first embodiment. However, in this embodiment, the gas mixed with the source gas is a nitrogen oxide gas, such as a nitrogen monoxide gas or a nitrogen dioxide gas. Nitric oxide gas or nitrogen dioxide gas is introduced from the gas inlet 1 into the plasma chamber 7.

In the examples, the amount of gas was controlled by the flow rate, and the change in the characteristics of the formed film was examined by changing the ratio to the flow rate of methane gas as the raw material gas. FIG. 2 shows that the hardness of the DLC film depends on the amount of the nitrogen monoxide gas or the nitrogen dioxide gas, and takes the maximum value of the hardness for a specific gas amount. In particular, in the case of nitric oxide, a large hardness of 35 GPa is exhibited at an introduction amount of 2%. The hardness was 23 GPa when there was no additional gas, which is the conventional example. On the other hand, the hardness could be greatly improved by mixing the nitrogen oxide gas with the raw material gas.

By the way, in order to examine the influence of the carbon oxide gas and the nitrogen oxide gas shown in the above embodiment on the hardness of the film, the hydrogen concentration in the film was measured. The measurement method uses ERDA (Elastic Recoil Detection), which detects high-speed ions incident on the sample and detects particles that are rebounded by elastic scattering.
Analysis) method was used. FIG. 5 shows the relationship between the hardness of the film formed in the example based on the above embodiment and the amount of hydrogen in the film, which is the measurement result. It can be seen that the smaller the amount of hydrogen in the DLC film, the higher the film hardness.
The film formed using only methane gas, which is a conventional example, shown as a comparative example has a hardness of 23 GPa, but the amount of hydrogen in the film is about 31 at.%. Therefore, in the embodiment of the present invention, by adding a small amount of oxygen-containing gas such as carbon oxide gas and nitrogen oxide gas to the source gas, hydrogen and oxygen in the film are combined and come out of the film, It is considered that the amount of hydrogen in the film is reduced, which contributes to the improvement in hardness.

As described above, according to the present embodiment, a DLC film is formed by mixing at least a nitric oxide gas or a nitrogen dioxide gas with a plasma of a methane gas as a raw material gas, thereby making it possible to compare with a conventional example. Thus, the hardness of the film can be greatly increased.

In this embodiment, methane gas is used as a raw material gas. However, similar results can be obtained by using other hydrocarbon gases such as ethylene gas.

(Embodiment 3) The method of forming a diamond-like carbon film in Embodiment 3 is a method of forming a DLC film while irradiating the substrate surface with light.

As the light source for light irradiation, three types having wavelengths of about 185 nm, 430 nm and 1.1 μm were used in the embodiment. Light was searched for a place in the plasma chamber where the influence of the plasma was small, and the light was set at a position where the substrate 10 in FIG. If it cannot be installed inside the apparatus, it is introduced into the plasma chamber 7 using a metal pipe (not shown) for guiding light, and is installed at a position where the substrate 10 can be directly irradiated with light. The light irradiation power is 5, 1
0 and 15 mW.

In the embodiment, ethylene gas is used as the raw material gas, the gas pressure is 1.0 Pa, and the input power is 200
W and the high frequency bias power were 100 W. Also DLC
And the total thickness of silicon was 100 nm.

As a substrate on which a film was formed, a silicon wafer having a diameter of 6 inches was used. The film forming method was as follows. First, a silicon layer serving as a base layer was formed to a thickness of about 2 nm in a sputtering chamber installed in the same apparatus, and then the substrate was moved to a plasma chamber 7 in a vacuum. Next, ethylene gas as a raw material gas was introduced from the gas inlet 1 and plasma 8 was generated by a microwave oscillator. Then, a magnetic field was generated in the magnet 6, and plasma of the ethylene gas was drawn to the substrate side. At this time, a substrate bias was applied to the substrate holder 9 by the high frequency power supply 3. Then, the power of the light irradiator was turned on, and the surface of the substrate was irradiated with light to form a film.

FIG. 3 is a diagram showing the result of the third embodiment. The figure shows the result of examining the relationship between the hardness and the light irradiation power measured by the method based on the nanoindentation test for each wavelength while changing the wavelength of the irradiation light.
It can be seen that when the light is not irradiated, which is a conventional example, the hardness is 30 GPa, whereas the film hardness of the DLC is increased by the light irradiation. Also, the shorter the wavelength, the greater the hardness. A maximum hardness of 40 GPa is obtained. This is because by irradiating the substrate with light during the formation of the DLC film, the molecules existing on the substrate are photoexcited and more activated,
As a result, it is considered that hydrogen and oxygen are combined and come out of the film, and the amount of hydrogen in the film is reduced.

As described above, according to the present embodiment, the DL
By irradiating the substrate surface with light when forming the C film, the hardness of the film can be greatly increased as compared with the conventional example. In addition, by using the method of the first or second embodiment together, it is possible to obtain higher effects.

(Embodiment 4) In the method of forming a diamond-like carbon film in Embodiment 4, when a DLC film is formed, an oxygen gas, a carbon monoxide gas, a carbon dioxide gas, a nitrogen monoxide gas is formed on a substrate surface. This is a method of forming a DLC film after adsorbing at least one gas selected from a gas and a nitrogen dioxide gas.

In the embodiment, the substrate on which the film is formed has a diameter of 6
An inch silicon wafer was used.

The film forming method was as follows. First, a silicon layer serving as a base layer was formed to a thickness of about 2 nm in a sputtering chamber installed in the same apparatus. Next, the substrate 10 is moved to the plasma chamber 7 in a vacuum, and the ultimate vacuum degree is 5 × 10 ⁻⁷ To.
After the vacuum was increased to rr, the gas to be adsorbed was introduced from the gas inlet 1 into the plasma chamber, and the gas was adsorbed on the substrate 10. The adsorption time was changed according to the time from the start of gas introduction. Next, a source gas for DLC film formation was introduced. Ethylene gas was used as a source gas. Plasma 8 was generated by the microwave oscillator 4, a magnetic field was generated in the magnet 6, and plasma of ethylene gas was drawn to the substrate side. At this time, a substrate bias was applied to the substrate holder 9 by the high frequency power supply 3. The gas pressure was 1.0 Pa. The input power was 200 W and the high frequency bias power was 100 W. The total thickness of DLC and silicon was 100 nm.

FIG. 4 is a diagram showing the result of the fourth embodiment. The figure shows the result of examining the relationship between the hardness measured by the method based on the nanoindentation test and the adsorption treatment time for each adsorption gas while changing the adsorption gas. When the conventional gas is not adsorbed, the hardness is 30.
It can be seen that the film hardness of the DLC is increased by the gas adsorption in contrast to GPa. And up to 35G
A hardness of Pa is obtained.

As described above, according to the present embodiment, the DL
By adsorbing gases such as oxygen gas, carbon monoxide gas, carbon dioxide gas, nitric oxide gas, and nitrogen dioxide gas on the substrate surface before forming the C film, the hardness of the film can be reduced as compared with the conventional example. It can be greatly increased.

[0045]

According to the present invention, when a DLC film is formed, the amount of hydrogen in the film can be reduced, and the hardness of the film can be improved. As a result, a DLC film having excellent abrasion resistance can be formed even when the thickness of the DLC film is reduced. Therefore, D which is suitable as a protective film for the slider sliding surface of the thin-film magnetic head and which at the same time secures the thinning, abrasion resistance and corrosion resistance.
An LC film can be realized.

[Brief description of the drawings]

FIG. 1 is a diagram showing the relationship between the hardness of a film formed by the method for forming a diamond-like carbon film and the amount of carbon dioxide in Embodiment 1.

FIG. 2 is a diagram showing the relationship between the hardness of a film formed by the method for forming a diamond-like carbon film and the amount of nitric oxide gas in Embodiment 2.

FIG. 3 is a diagram showing a relationship between hardness and light irradiation power of a film formed by a method for forming a diamond-like carbon film in Embodiment 3.

FIG. 4 is a diagram showing a relationship between hardness of a film formed by a method for forming a diamond-like carbon film and a gas adsorption treatment time in Embodiment 4.

FIG. 5 is a diagram showing the relationship between the film hardness and the amount of hydrogen in the film formed by the method for forming a diamond-like carbon film in Embodiments 1 and 2.

FIG. 6 is a schematic diagram of a film forming apparatus used for performing a method for forming a diamond-like carbon film according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Gas inlet 2 ECR plasma CVD apparatus 3 High frequency power supply 4 Microwave oscillator 5 Waveguide 6 Magnet 7 Plasma chamber 8 Plasma 9 Substrate holder 10 Substrate

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Tatsutoshi Suenaga 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. F-term (reference) 4K030 AA10 AA14 BA28 CA04 CA12 FA02 LA19 5D042 NA02 PA08 RA02 SA03

Claims (6)

[Claims] 1. A method for forming a diamond-like carbon film by plasma CVD, wherein a film is formed by mixing at least a carbon monoxide gas or a carbon dioxide gas in a film-forming raw material gas. Method of forming a film. 2. A method for forming a diamond-like carbon film by plasma CVD, wherein the film is formed by mixing at least a nitrogen monoxide gas or a nitrogen dioxide gas with a film-forming raw material gas. Formation method. 3. A method of forming a diamond-like carbon film by plasma CVD, wherein the film is formed while irradiating a substrate surface on which the film is formed with light selected from wavelengths ranging from far infrared rays to ultraviolet rays. A method for forming a diamond-like carbon film. 4. The diamond-like carbon film according to claim 1, wherein the film is formed while irradiating the substrate surface on which the film is formed with light selected from wavelengths ranging from far infrared rays to ultraviolet rays. Formation method. 5. A plasma CV on a substrate surface provided with an underlayer.
In the method of forming a diamond-like carbon film according to D, before forming the diamond-like carbon film, oxygen gas, carbon monoxide gas, carbon dioxide gas, nitrogen monoxide gas, and nitrogen dioxide A method for forming a diamond-like carbon film, comprising forming a diamond-like carbon film after adsorbing at least one selected gas. 6. The method for forming a diamond-like carbon film according to claim 1, wherein a diamond-like carbon film is formed on a slider sliding surface of the thin-film magnetic head.