JPH0797687A - Formation of diamond-like carbon film and manufacture of magnetic head and magnetic disk - Google Patents

Abstract

PURPOSE:To establish the formation of diamond-like carbon film which has excellent mass-productivity and is appropriately used as the protective film of a magnetic head, magnetic disk, etc. CONSTITUTION:A target 4 consisting of graphite is placed on a cathode 2 in a film formation chamber 1 and the material to be treated 7 is placed on the substrate holder 5 which is disposed opposite to the cathode 2. Then the diamond-like carbon film is formed on the surface of the material to be treated 7 by using the DC magnetron sputtering method. At this time, the gas composition is adjusted so that the molar ratio of the gaseous hydrogen to the gaseous mixture consisting of gaseous hydrogen and an inert gas is in the range of 0.05 to 0.1 and the voltage of the substrate holder 5 to the earth voltage also is adjusted to -30 to -80V. Thus the diamond-like carbon film having >=1400GPa hardness can be formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a diamond-like carbon film (hereinafter referred to as a DLC film, DLC: Diamond Like Carbon).
), Particularly to a method for forming a DLC film suitable for protecting a magnetic head, a magnetic disk, etc., and a method for manufacturing a magnetic head and a magnetic disk having a diamond-like carbon film on the surface.

[0002]

2. Description of the Related Art Generally, since a DLC film has high hardness and a low friction coefficient, it has been attracting attention as a protective film for protecting the surface of, for example, a magnetic head or a magnetic disk. For example, in a fixed magnetic disk device, further miniaturization, large capacity, and low cost have been advanced, and it has become essential to use a magnetic recording medium with high density. As a result, the number of collisions and scratches between the magnetic head and the magnetic disk increases, and surface destruction (hereinafter referred to as “crash”) is likely to occur on these surfaces.

Recently, a protective film for protecting the surfaces of magnetic heads and magnetic disks has been installed for the purpose of avoiding problems such as crashes. In order to realize a DLC film, research and development such as film forming conditions in various film forming methods have been actively conducted.

A conventional method for forming a DLC film is, for example, ECR-CVD (: Electron Cy--clotron Resonance).
-Chemical Vapor Deposition) film forming method, plasma CVD film forming method, DC magnetron sputtering film forming method, and the like.

[0005]

[Problems to be Solved by the Invention] However, ECR
The hardness of the DLC film is at most about 90 GPa in the film-forming method by CVD, and the hardness of the DLC film is at most 100-140 GPa in the film-forming method by plasma CVD. A DLC film having sufficient hardness cannot be realized. Further, all of these CVD film forming methods require a complicated and expensive apparatus, and moreover, maintenance such as cleaning of contaminants in the chamber of the film forming apparatus must be frequently performed. is there.

On the other hand, since the film forming method by DC magnetron sputtering is excellent in terms of mass productivity and easy maintenance of the device, it is attracting attention as a method for forming a DLC film, and the film forming conditions and the like are actively studied. However, there is a problem that the hardness of the DLC film that can be realized by this film forming method is about 130 GPa at the most, and the hardness is not sufficient to protect the magnetic head and the like.

The present invention has been made in view of the above circumstances, provides a method for forming a DLC film which is excellent in mass productivity and is suitable as a protective film for a magnetic head, a magnetic disk, and the like, and wear resistance. It is an object of the present invention to provide a method of manufacturing a magnetic head and a magnetic disk having excellent resistance and impact resistance.

[0008]

In order to achieve such an object, a method for forming a DLC film according to the present invention as set forth in claim 1, wherein a target made of graphite is installed on a cathode in a film forming chamber, When the object to be processed is placed on the substrate holder arranged to face the cathode and the diamond-like carbon film is formed on the surface of the object to be processed by the DC magnetron sputtering method, the gas composition is hydrogen gas. The molar ratio of the hydrogen gas to the mixed gas of the inert gas and the inert gas is in the range of 0.05 to 0.1, and the voltage of the substrate holder is −30 with respect to the ground voltage.
It is characterized in that it is set to -80V.

In the method of manufacturing a magnetic head according to the second aspect of the present invention, when the diamond-like carbon film is formed on the surface of the magnetic head by the DC magnetron sputtering method, a graphite target is placed on the cathode in the film forming chamber. The magnetic head is installed on the substrate holder arranged facing the cathode, and the gas composition is set such that the molar ratio of the hydrogen gas to the mixed gas of the hydrogen gas and the inert gas is 0.05 to. The voltage of the substrate holder with respect to the ground voltage is set to -3.
It is characterized in that it is set to 0 to -80V.

In the method of manufacturing a magnetic disk according to the present invention as defined in claim 3, when the diamond-like carbon film is formed on the surface of the magnetic head by the DC magnetron sputtering method, graphite is formed on the cathode in the film forming chamber. A target is placed, a magnetic disk is placed on a substrate holder arranged so that the cathode faces each other, and a gas composition is set such that a molar ratio of hydrogen gas to a mixed gas of hydrogen gas and an inert gas is 0. It is characterized in that the voltage is in the range of 05 to 0.1 and the voltage of the substrate holder with respect to the ground voltage is -30 to -80V.

That is, the present invention provides a highly hard DL having sufficient durability as a protective film for a magnetic head or a magnetic disk.
It was created as a result of earnest research from the viewpoint that it is necessary to establish a method for forming a C film based on the DC magnetron sputtering method, which is excellent in mass productivity.

The present inventors have found that the hardness of the DLC film formed by the DC magnetron sputtering method changes depending on the voltage of the substrate holder with respect to the ground voltage (hereinafter referred to as DC bias voltage), and the DLC film is added to the sputtering gas. We paid attention to the two points that it changes depending on the amount of hydrogen gas added. Then, as a result of conducting experiments and studies to find conditions for forming a DLC film having a higher hardness by making good use of the respective good effects of the DC bias voltage and the amount of hydrogen gas added on the hardness of the DLC film, the gas composition was The molar ratio of hydrogen gas to a mixed gas composed of hydrogen gas and an inert gas (hereinafter, referred to as mixed gas) is in the range of 0.05 to 0.1, and D
It has been found that a DLC film having a hardness of 140 GPa or more can be obtained when the C bias voltage is set to -30 to -80V.

In the method of forming the DLC film and the method of manufacturing the magnetic head and the magnetic disk according to the present invention, Ar is suitable as the inert gas, but He, Ne,
A gas such as Kr may be used. The gas composition is such that the molar ratio of hydrogen gas to the mixed gas is 0.05 to 0.1.
Is desirable. In this range, more active H * is generated in the plasma, so that the plasma state becomes closer to the diamond generation condition and the H ^* impacts the DLC film formed on the surface of the object to be processed. Then, since the SP3 bond, which is a graphite bond, is selectively etched and removed from this surface, the ratio of SP3 bond to SP2 in the DLC film becomes high, and a DLC film having higher hardness is formed. Here, the SP2 bond is called a diamond bond. Further, when the molar ratio of hydrogen gas to mixed gas is less than 0.05, the plasma state largely deviates from the diamond production conditions, so the ratio of SP2 bonds to SP3 bonds in the DLC film increases, and the activity in plasma increases. Since H * is reduced, the SP2 bond remains without being etched, so that the hardness of the DLC film is lowered. Further, when the molar ratio of the hydrogen gas exceeds 0.1, the ratio of the polymer-based C and H bonds in the DLC film rapidly increases, and the hardness of the DLC film decreases.

On the other hand, the DC bias voltage is -30 to -80.
It is desirable to set it to V. DC bias voltage is -30
If the voltage is less than V, the energy of Ar ⁺ in the plasma drawn to the substrate holder side and impacting the DLC film is low, so that SP2 bonds cannot be selectively removed from the surface of the DLC film, and therefore the DLC film cannot be selectively removed. Since the proportion of SP2 bonds in the film does not decrease, the hardness of the DLC film decreases. When the DC bias voltage exceeds -80V,
Since the energy of Ar ⁺ in the plasma that impacts the DLC film becomes extremely large, the SP2 bond is removed by etching from the surface of the DLC film, and the SP3 bond is also destroyed or etched. Therefore, the hardness of the DLC film is low. Become.

[0015]

In the method of forming the DLC film and the method of manufacturing the magnetic head and the magnetic disk according to the present invention, the gas composition is such that the molar ratio of hydrogen gas to the mixed gas is 0.05 to.
Since the DC bias voltage was set to be in the range of 0.1 and the DC bias voltage was set to -30 to -80V, the DLC
Since the ratio of SP3 bond to SP2 bond in the film can be increased, a DLC film having a hardness of 140 GPa or more can be formed, and the DLC film is particularly suitable for protecting a magnetic head or a magnetic disk. Can be formed.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

Example 1 A method of forming a DLC film according to the present invention will be described with reference to FIG. FIG. 1 is a schematic sectional view showing an example of a film forming apparatus used for forming a DLC film. In FIG. 1, 1 is a film forming chamber, 2 is a cathode provided in the film forming chamber 1, 3 is a DC power source for applying a negative voltage to the cathode 2, and 4 is graphite arranged on the cathode 2. Target 5 is a substrate holder arranged so as to face the cathode 2, and 6 is DC on the substrate holder 5.
A DC bias power source for applying a bias voltage, 7 an object to be processed installed on the substrate holder 5, 8 a gas introduction pipe for introducing a sputtering gas into the film forming chamber 1 from a gas supply source (not shown), 9 Is an exhaust pipe connected to an exhaust device (not shown).

Here, the cathode 2 has a built-in magnet (not shown) for applying a magnetic field in the vicinity of the surface thereof, and the substrate holder 5 has a DC bias power source 6 of a desired size of DC. A bias voltage can be applied. Further, the sputtering gas is a mixed gas of hydrogen gas and Ar gas, and after the molar ratio of the hydrogen gas to the mixed gas is set to a desired value in a gas supply source (not shown), the film is formed through the gas introduction pipe. It is introduced indoors.

Next, a method for forming a DLC film according to the present invention will be described. First, as the object to be processed 7, a 3 inch diameter Si wafer having a smooth surface is placed on the substrate holder 5,
A target 4 made of graphite is installed on the cathode 2. Here, the distance between the target 4 and the Si wafer is 50 mm, and the substrate holder 5 is at room temperature. Next, after exhausting the inside of the film forming chamber 1 by an exhaust device (not shown), a mixed gas of hydrogen gas and Ar gas is introduced into the film forming chamber 1 as a sputtering gas, and then a DC bias power source 6 to -30.
A DC bias voltage of -80 V is applied to the substrate holder 5, 300 W of electric power is applied from a DC power source, plasma is generated in the film forming chamber 1 to sputter the target 4, and the target 4 is sputtered on the Si wafer. A DLC film is formed with a thickness of 1000A. The molar ratio of the hydrogen gas to the mixed gas at this time is in the range of 0.05 to 0.1.

The hardness of the DLC film thus obtained was measured by a thin film hardness meter (NHA, MHA-400) and the results are shown in Table 1.

[0021]

[Table 1]

The three numbers in each column of the table are film forming conditions based on the combination of the molar ratio of hydrogen gas to mixed gas shown on the left side of the table and the DC bias voltage shown on the upper side of the table. It shows the hardness of the DLC film obtained below. Of these three numbers, the left number represents the minimum measured value, the middle number represents the average measured value, and the right number represents the maximum measured value.

As can be understood from this table, in forming the DLC film by the DC magnetron sputtering method,
A target 4 made of graphite is placed on the cathode 2, and an object 7 to be treated is placed on a substrate holder 5 arranged so as to face the cathode 2, and the gas composition is hydrogen gas and Ar gas. While keeping the molar ratio of hydrogen gas to the mixed gas in the range of 0.05 to 0.1,
The DC bias voltage applied to the substrate holder 5 is -30 to-
Since it is set to 80V, the hardness is 140 to 190G
A DLC film of Pa can be formed.

Next, the fact that the DLC film formed according to the present invention has higher hardness will be considered with reference to FIGS. 2 to 5. FIG. 2 is an explanatory diagram showing the relationship between the DC bias voltage (V) and the film formation rate (A / min) of the DLC film. In FIG. 2, the vertical axis represents the deposition rate of the DLC film,
The horizontal axis represents the DC bias voltage. Here, only Ar gas was used as the sputtering gas, the DC bias voltage was set to 0 to -400 V, and the power supplied by the DC power source was set to 300 W to form the DLC film.

From FIG. 2, the DC bias voltage is 0 to -15.
In the range of 0 V, Ar ⁺ is drawn to the substrate holder 5 side with kinetic energy according to the magnitude of the DC bias voltage, and the DLC film is further impacted and etched, so that the DC bias voltage is set to a negative value. It can be seen that the film formation rate decreases as the value increases. Further, when the DC bias voltage exceeds -150 V, the kinetic energy of Ar ⁺ is further increased and the surface of the Si substrate is also etched. Therefore, it is understood that it is not preferable to excessively increase the voltage applied to the substrate holder 5.

FIG. 3 shows DC bias voltage (V) and DLC.
It is explanatory drawing which shows the relationship with the hardness (GPa) of a film | membrane. Figure 3
In, the vertical axis represents the hardness of the DLC film and the horizontal axis represents the DC bias voltage. Here, Ar is used as the sputtering gas.
Only gas is used, DC bias voltage is 0 to 80V
And set the power supplied by the DC power source to 300 W, 10
A DLC film of 00A was formed.

From FIG. 3, the DC bias voltage is about -50V.
It can be seen that the hardness of the DLC film shows the maximum value at.
This is because the DC bias voltage is in the range of 0 to -50V.
Ar ⁺ is drawn toward the substrate holder 5 side with kinetic energy according to the magnitude of the DC bias voltage, and further D
By bombarding the LC film, the SP2 bond of the SP3 bond which is a diamond bond and the SP2 bond which is a graphite bond constituting the DLC film is selectively removed. Therefore, the ratio of the SP3 bond to the SP2 bond occupied in the DLC film is ratio. It is considered that the hardness increases and the hardness of the DLC film increases. When the DC bias voltage exceeds -50V,
The kinetic energy of Ar ⁺ becomes even larger and DL
It is believed that the C film is bombarded to break or etch the SP3 bond and reduce the hardness of the DLC film.

FIG. 4 is an explanatory diagram showing the relationship between the molar ratio of hydrogen gas to the mixed gas and the hardness (GPa) of the DLC film. In FIG. 4, the vertical axis represents the hardness of the DLC film, and the horizontal axis represents the molar ratio of hydrogen gas to the mixed gas. Here, the molar ratio of the hydrogen gas to the mixed gas is set in the range of 0 to 0.3, the DC bias voltage is set to zero, the input power from the DC power source is set to 300 W, and the DLC of 1000 A is set.
A film was formed.

From FIG. 4, when the molar ratio of hydrogen gas to mixed gas is about 0.1, the hardness of the DLC film has a maximum value of about 13
It can be seen that it shows 5 GPa. This is because when the molar ratio of hydrogen gas is in the range of 0 to 0.1, hydrogen gas is activated in plasma to generate active species (H ^* ), and the plasma state is changed to a high temperature / high pressure state. By making the diamond formation conditions closer to the diamond formation conditions, and by causing H *, which has become an active species, to impinge on and bombard the surface of the DLC film exposed to plasma, the SP2 bond, which is a graphite bond, is selectively etched. S for SP2 binding in the membrane
It is thought that it may increase the rate of P3 binding. Further, when the molar ratio of hydrogen gas exceeds 0.1, the concentration of hydrogen in the plasma increases, so that hydrogen enters the DLC film and the ratio of C-H bond in the polymer system is rapidly increased. It is considered that the hardness of the film decreases.

Further, FIG. 5 shows the molar ratio of hydrogen gas to mixed gas and the hardness (GP) of the DLC film when the DLC film is formed while applying a DC bias voltage to the substrate holder.
It is explanatory drawing which shows the relationship with a). In FIG. 5, the vertical axis represents the hardness of the DLC film and the horizontal axis represents the molar ratio of hydrogen gas to the mixed gas. In addition, here, the molar ratio of the hydrogen gas to the mixed gas is 0 to 0.3, and the DC vice voltage is -5.
0V, 300W input power from the DC power supply,
A 1000 A DLC film was formed.

From FIG. 5, the hardness of the DLC film shows a maximum value of about 175 GPa when the molar ratio of hydrogen gas is around 0.1,
It can be seen that when it exceeds 1, it gradually decreases. This is due to the DL of the C and H bond of the polymer system considered from FIG.
It is considered that this is because the ratio occupied in the C film increases. The structure of the DLC film thus obtained is TEM.
Observation and electron beam diffraction revealed that it was a very homogeneous amorphous.

According to FIG. 5, the DC bias voltage is -50.
V and the molar ratio of hydrogen gas to mixed gas is 0.05
When a DLC film is formed with a thickness of 0.1 to 140 GPa, which has a high hardness that cannot be obtained by the DC magnetron sputtering method.
It can be seen that the above hardness can be obtained.

As described above, the DLC according to the present invention
The method of forming the film does not consist only of the gas composition in which the molar ratio of the hydrogen gas to the mixed gas is in the range of 0.05 to 0.1, and the bias voltage is merely in the range of -30 to -80.
It goes without saying that just setting it to V did not work. That is, the present invention provides good results only under the condition that the gas composition is such that the molar ratio of hydrogen gas to mixed gas is in the range of 0.05 to 0.1 and the bias voltage is set to -30 to -80V. Will be obtained.

(Example 2) The method of manufacturing a magnetic head of the present invention is the same as the method of the configuration shown in Example 1 except that a magnetic head is used as the object 6 to be processed in Example 1. FIG. 6 shows a cross-sectional view of a main part of a magnetic head manufactured according to the present invention. In FIG. 6, 10 is a magnetic head, 1
Reference numeral 1 is a non-magnetic ceramic, 12 and 13 are high-permeability magnetic materials such as ferrite, 14 and 15 are adhesive layers, 16 is a gap, 17 is a coil, and 18 is a DLC film formed on the head portion of the magnetic head 10. is there. Here, the DLC film was 100 to 250A.

When a CSS test (CSS: Contact Start and Stop) was conducted using the magnetic head thus obtained, no increase in the starting torque (g · cm) was observed, and the surface of the head was scratched. There were no scratches. As described above, according to the method of manufacturing a magnetic head of the present invention, it is possible to provide a magnetic head having sufficient wear resistance and impact resistance even when an extremely thin DLC film is used as a protective film. Even if the gap between the magnetic head and the magnetic disc is required to be further narrowed in the disc device, it is possible to sufficiently meet the demands of the times. Further, in the present embodiment, an example of the levitation type magnetic head was shown as the magnetic disk, but it is needless to say that it is also suitably used for a VTR magnetic head used for a magnetic tape, for example.

(Third Embodiment) The magnetic disk manufacturing method of the present invention is the same as that of the second embodiment except that a fixed magnetic disk is used instead of the magnetic head 10 of the second embodiment.

Therefore, according to the method of manufacturing a magnetic disk of the present invention, it is possible to provide a magnetic disk having sufficient wear resistance and impact resistance even if an extremely thin DLC film is used as a protective film, and hence a fixed disk will be provided in the future. Even if the device is required to further narrow the gap between the magnetic head and the magnetic disk, it is possible to sufficiently meet the demands of the times.

[0038]

According to the method of forming a DLC film of the present invention, a target made of graphite is placed on the cathode in the film forming chamber, and the object to be treated is placed on the substrate holder arranged facing the cathode. In forming the DLC film on these surfaces by the DC magnetron sputtering method,
The gas composition is such that the molar ratio of hydrogen gas to the mixed gas of hydrogen gas and inert gas is in the range of 0.05 to 0.1, and the voltage of the substrate holder with respect to the ground voltage is -30 to -30. Since it is characterized by being set to −80 V, DL having a hardness of 140 GPa or more
It is possible to form a C film, and thus it is possible to form a DLC film which is particularly suitable for protecting a magnetic head, a magnetic disk, or the like.

Further, since the method of manufacturing the magnetic head and the magnetic disk according to the present invention employs the same film forming conditions as the method of forming the DLC film, the protective film is 100
Since an extremely thin DLC film of about 250 A can be formed, it is possible to provide a method of manufacturing a magnetic head and a magnetic disk having excellent wear resistance and impact resistance.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an example of a film forming apparatus used for explaining a method for forming a DLC film according to the present invention.

FIG. 2 is an explanatory diagram showing a relationship between a DC bias voltage and a film formation rate of a DLC film.

FIG. 3 is an explanatory diagram showing a relationship between a DC bias voltage and hardness of a DLC film.

FIG. 4 is an explanatory diagram showing the relationship between the molar ratio of hydrogen gas to mixed gas and the hardness of the DLC film.

FIG. 5 is an explanatory diagram showing the relationship between the molar ratio of hydrogen gas to mixed gas and the hardness of the DLC film when the DLC film is formed while applying a DC bias voltage to the substrate holder.

FIG. 6 is a cross-sectional view of essential parts of a magnetic head manufactured by the method of manufacturing a magnetic head of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 film-forming chamber 2 cathode 3 DC power supply 4 target 5 substrate holder 6 DC bias power supply 7 object to be processed 8 gas introduction pipe 9 exhaust pipe 10 magnetic head 11 non-magnetic ceramics 12, 13 high-permeability magnetic substance 14, 15 adhesive layer 16 Gap 17 Coil 18 DLC film

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication C30B 29/04 M 8216-4G G11B 5/127 F 7303-5D 5/84 B 7303-5D (72 ) Inventor Isao Nakamura 1-7 Yukiya Otsukacho, Ota-ku, Tokyo Alps Electric Co., Ltd.

Claims (3)

[Claims] 1. A target made of graphite is installed on a cathode in a film forming chamber, an object to be processed is installed on a substrate holder arranged facing the cathode, and the object is processed by a DC magnetron sputtering method. In forming the diamond-like carbon film on the surface of the object, the gas composition is set such that the molar ratio of hydrogen gas to the mixed gas of hydrogen gas and inert gas is in the range of 0.05 to 0.1. , The voltage of the substrate holder with respect to the ground voltage is -3
A method for forming a diamond-like carbon film, characterized in that it is set to 0 to -80V. 2. When forming a diamond-like carbon film on the surface of a magnetic head by the DC magnetron sputtering method, a target made of graphite is placed on the cathode in the film forming chamber, and the substrate is arranged so as to face the cathode. A magnetic head is installed on the holder so that the gas composition is such that the molar ratio of hydrogen gas to the mixed gas of hydrogen gas and inert gas is in the range of 0.05 to 0.1, and the ground voltage is The voltage of the substrate holder with respect to −3
A method of manufacturing a magnetic head, wherein the magnetic head has a voltage of 0 to -80V. 3. When forming a diamond-like carbon film on the surface of a magnetic disk by the DC magnetron sputtering method, a target made of graphite is placed on the cathode in the film forming chamber, and the substrate is arranged so as to face the cathode. Place the magnetic disk on the holder and set the gas composition to
The molar ratio of the hydrogen gas to the mixed gas of the hydrogen gas and the inert gas is in the range of 0.05 to 0.1, and the voltage of the substrate holder with respect to the ground voltage is -30 to -80V. A method of manufacturing a magnetic disk characterized by the above.