JP3473703B2 - Magnetic device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a magnetic device having a carbon protective film formed by a plasma CVD method as a protective film.
It's about vices .

[0002]

2. Description of the Related Art The plasma CVD method is widely used in the field of electronic devices and is a practical technique used for forming various materials and coating. However, given its potential, it is a technology that is still evolving and there are many unknowns. It can be said that the equipment and operation method are in the process of optimization. Reflecting such circumstances, a new plasma CVD method has been proposed for various substances and is being attempted in practice.

As a characteristic of the plasma CVD method as a material process, firstly, there are various applications. First, there are various materials that can be synthesized such as ceramics, metals, semiconductors, and organic polymers. In addition, thin film, fiber,
Materials of various shapes such as powder, bulk, and composite can be obtained. Furthermore, it is also used for micron / submicron microfabrication represented by VLSI.

Here, as compared with the plasma CVD method, which is widely used in the electronic device field, as compared with the vapor deposition method, the vapor deposition method is limited to metals and special organic substances. Regarding the synthesis of the composite, it is possible with the plasma CVD method that other methods such as filling the voids of the carbon fiber matrix with SiC and densifying it to form a composite can not be easily realized. The plasma CVD method is an indispensable technique for forming a uniform film on a submicron-scale uneven surface even in fine processing.

The second characteristic of the plasma CVD method is that it is suitable for the synthesis of high-purity materials because it can use high-purity gas. Since it is generally difficult to directly purify an individual, in order to synthesize a high-purity substance, a gas or a liquid state is always used in the purification step. For example, in order to obtain a high-purity silicon as a single crystal pulling raw material utilizes SiH _X C1 _4-X gas in the purification process. Therefore, the plasma CVD method that can use high-purity gas is suitable for the synthesis of high-purity materials.

The third feature is that high-level control is possible. It is possible to obtain materials having different compositions and crystal structures from the same raw material system. For example, SiH ₄ and NH
Silicon nitride can be synthesized from ₃ and. Regarding silicon nitride, there are various types such as composition and crystal structure,
They are roughly classified into crystalline and amorphous. If the substrate temperature is raised to 1200 ° C or higher by the plasma CVD method, crystalline Si ₃ N ₄
At around 00 ° C, an amorphous material that is almost crystalline can be synthesized. Furthermore, if the plasma CVD method is performed at a low temperature, amorphous Si
N _X H _y can also be used to synthesize various materials for x · y. These various types of silicon nitride are used properly according to the application.

As described above, it is a feature of the plasma CVD method that various materials can be synthesized with high purity and controllability. On the other hand, variety, for example, that it is possible to synthesize from crystalline to amorphous, from thin film to powder with the same raw material system means that high process control is important in the plasma CVD method. There is.

In the field of electronic devices, application of carbon films as a protective film for devices has been studied.

Conventionally, a sputtering method, which is a physical vapor deposition method, has been used as a method for forming a carbon protective film.
When the carbon protective film is formed by using the sputtering method,
As described in the prior art, it is very difficult to form a uniform film on the uneven surface of submicron scale. Further, regarding the film quality of the carbon protective film, when the film is formed by using the sputtering method, it is very difficult to control the film quality by controlling the film forming process because it largely depends on the material of the sputtering target material. is there.

Therefore, in recent years, studies have been actively conducted to apply a carbon protective film formed by the plasma CVD method as a protective film of a device.

[0011]

However, when applying a carbon protective film formed by the plasma CVD method to a device, it is an important issue to enable high-level process control of the plasma CVD method. .

The first problem is that high-speed film formation must be possible without changing the film quality. When applying a thin film to a device, it is one of the biggest problems in process control that film formation can be performed at high speed.

Film-forming substances in the plasma CVD method are various kinds of radicals and ions generated in a gas phase, clusters and ultrafine particles. These ratios depend on the film forming conditions. Usually, when considering high-speed film formation, it is attempted to increase the pressure of the film formation gas and increase the applied voltage to improve the film formation rate.

When high-speed film formation is performed with a high gas pressure and a high voltage, the probability of collision of radical molecules in the gas phase increases, resulting in formation of clusters and ultrafine particles, resulting in a change in film quality. Become. In addition, the radical species also contribute differently to the film formation, and the film quality changes.

In the case of forming the carbon protective film using the plasma CVD method, the physical properties of diamond, hard carbon film, and polymer-like soft carbon film are largely changed depending on the film forming conditions. If an attempt is made to increase the deposition rate of the carbon protective film by the method as described above, the film quality will change and the carbon protective film that can be adapted to the intended device will not be deposited.

As described above, in the plasma CVD method, it is extremely difficult and an important subject to perform high-speed film formation without deteriorating the film quality.

The second problem is the problem of adhesion of the film synthesized by the plasma CVD method to the device.
In particular, when applying a film synthesized by the plasma CVD method as a carbon protective film, it is an important issue to improve the adhesion to the device in order to utilize the mechanical properties.

If the film forming conditions are changed in the same manner as described above in order to improve the adhesion, the film quality also changes, and the desired film quality cannot be obtained.

As a third problem, in the case of a carbon protective film formed by the plasma CVD method, the formed carbon protective film is required to have mechanical strength. However, as described above, in the case of forming the carbon protective film using the plasma CVD method, the physical properties of diamond, hard carbon protective film, and polymer soft carbon protective film are largely changed depending on the film forming conditions. Thus, it is very difficult to form a carbon protective film that exhibits excellent mechanical properties under all film forming conditions.

As described above, in the process control of the plasma CVD method, it is an important subject to improve the adhesion to the device without deteriorating the film quality.

The present invention solves the above-mentioned conventional problems. In the process control of the plasma CVD method, a high-speed film formation is possible without deteriorating the film quality, and a carbon protective film having good adhesion to the device to be formed. The purpose is to be able to synthesize.

[0022]

In order to solve this problem, a magnetic device of the present invention has a first magnetic layer and is provided on the sliding surface side of the first magnetic layer with respect to the medium. Was
Having a first buffer layer, a thin film magnetic head having a first carbon protective film provided on the first buffer layer, a second magnetic layer on the substrate, the second magnetic the provided on the sliding surface side of the thin film magnetic head in layers
And 2 of the buffer layer, the second a magnetic device that includes a magnetic disk and a second carbon protective film provided on the buffer layer, the first and second back <br / > The fur layer is the same member, and the first and second carbon protection
The films are the same member, and the first and second buffer layers each include at least one of Ta, Si, Ti, Mo, Cu, and Ge. Further, the carbon protective film is formed by using the plasma CVD method.

[0023]

According to the present invention, it is possible to solve the problems in the process when the carbon protective film is formed by using the plasma CVD method.

First, the film formation rate can be improved without changing the film quality of the carbon protective film. Secondly, the adhesion of the carbon protective film to the substrate can be improved. Thirdly, the film quality of the carbon protective film to be formed can be made excellent in abrasion resistance. The operation will be described below.

When a film is formed by a plasma CVD method using a gas in which an inert gas such as Ar is mixed on a target substrate, the substrate is etched due to the influence of plasma. Due to the action of this etching, the film forming rate of the target film is lowered. Therefore, in the present invention, by providing a material having a low sputtering rate as a buffer layer on the substrate, it is possible to prevent the film formation rate from being lowered due to the etching action.

Further, it is apparent that the adhesion of the carbon protective film to the target substrate varies greatly depending on the material of the substrate. In general, it is also known that the carbon protective film has a weak adhesion to metal materials. Therefore, according to the present invention, by providing a material having a diamond lattice constant of 0.3567 nm on the substrate as a buffer layer, the compatibility between the materials is improved at the boundary between the buffer layer and the carbon protective film. It is possible to improve the adhesion of the to the substrate.

In addition, when a carbon protective film is used, it is necessary to form a carbon protective film having a high diamond property in order to obtain mechanical properties. However, when the carbon protective film is formed by using the plasma CVD method, the film quality of the carbon protective film is largely changed depending on the film forming conditions as described in the problem, and it is difficult to obtain the target film having high diamond property. Therefore, according to the present invention, by providing a material having a diamond structure as a buffer layer on the substrate as a buffer layer, the carbon protective film formed on this buffer layer exhibits homoepitaxial growth-like behavior. A high carbon protective film can be formed.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is a hard disk that is a magnetic disk.
And carbon thin film heads that are magnetic heads.
The protective film was formed, and the following examples 1 to 6 are applied as the carbon protective film to electronic devices.
For an example of forming a protective film for a hard disk on
Then, a film is formed as a protective film for the thin film head in Examples 7 to 10.
The performed example will be described . 1 Contact with an embodiment of the present invention
FIG. 3 is a film cross-sectional view showing the basic configuration of a hard disk ,
Reference numeral 1 is a carbon protective film, 2 is a buffer layer, and 3 is a magnetic layer of a hard disk. A cobalt-based material is used for the magnetic layer 3.

Example 1 A film was formed on the magnetic layer 3 using tantalum as the material of the buffer layer 2 shown in FIG.
Here, the sputtering rate of tantalum with respect to the Ar ion energy of 500 eV is 0.57. The lattice constant is 0.306 nm.

The tantalum film to be the buffer layer 2 was formed by the sputtering method.

The carbon protective film 1 was formed on the buffer layer 2 by using the plasma CVD method. The film forming conditions are a mixed gas of argon and methane as a source gas, a film forming gas pressure of 0.1 Torr and a film forming voltage of 1000V.

Example 2 A film was formed on the magnetic layer 3 using silicon as the material of the buffer layer 2 shown in FIG. Here, the sputtering rate of silicon for Ar ion energy of 500 eV is 0.50. The crystal structure has a diamond structure.

The silicon film to be the buffer layer 2 was formed by the sputtering method.

The carbon protective film 1 was formed on the buffer layer 2 by using the plasma CVD method. The film forming conditions are a mixed gas of argon and methane as a source gas, a film forming gas pressure of 0.1 Torr and a film forming voltage of 1000V.

Example 3 A film was formed on the magnetic layer 3 using titanium as the material of the buffer layer 2 shown in FIG. Here, the sputtering rate of titanium for Ar ion energy of 500 eV is 0.51.

The titanium film to be the buffer layer 2 was formed by the sputtering method.

The carbon protective film 1 was formed on the buffer layer 2 by using the plasma CVD method. The film forming conditions are a mixed gas of argon and methane as a source gas, a film forming gas pressure of 0.1 Torr and a film forming voltage of 1000V.

Example 4 Molybdenum was used as the material of the buffer layer 2 shown in FIG. 1 to form a film on the magnetic layer 3. Here, the sputtering rate of molybdenum with respect to the Ar ion energy of 500 eV is 0.80.

The molybdenum film to be the buffer layer 2 was formed by the sputtering method.

The carbon protective film 1 was formed on the buffer layer 2 by using the plasma CVD method. The film forming conditions are a mixed gas of argon and methane as a source gas, a film forming gas pressure of 0.1 Torr and a film forming voltage of 1000V.

Example 5 Copper was used as the material for the buffer layer 2 shown in FIG. 1 to form a film on the magnetic layer 3. Here, the lattice constant of copper is 0.315 nm.

The copper film to be the buffer layer 2 was formed by the sputtering method.

The carbon protective film 1 was formed on the buffer layer 2 by using the plasma CVD method. The film forming conditions are a mixed gas of argon and methane as a source gas, a film forming gas pressure of 0.1 Torr and a film forming voltage of 1000V.

Example 6 Germanium was used as the material of the buffer layer 2 shown in FIG. 1 to form a film on the magnetic layer 3. Here, the crystal structure of germanium has a diamond structure.

The germanium film to be the buffer layer 2 was formed by the sputtering method.

The carbon protective film 1 was formed on the buffer layer 2 by using the plasma CVD method. The film forming conditions are a mixed gas of argon and methane as a source gas, a film forming gas pressure of 0.1 Torr and a film forming voltage of 1000V.

Comparative Example 1 As Comparative Example 1, the carbon protective film 4 was formed directly on the magnetic layer 5 of the hard disk without providing the buffer layer as shown in the film sectional view of FIG. A cobalt-based material is used for the magnetic layer 5.

The carbon protective film 4 was formed on the magnetic layer 5 by using the plasma CVD method. The film forming conditions are a mixed gas of argon and methane as a source gas, a film forming gas pressure of 0.1 Torr and a film forming voltage of 1000V.

[0049] Figure 3 is a membrane cross-sectional view showing a basic structure of a thin film head <br/> in the real施例of the present invention, 6 carbon protective film, 7
Is a buffer layer, and 8 is a magnetic layer of a thin film head. A1 ₂ O ₃ TiC was used as the material of the magnetic layer 8 of this thin film head.

Example 7 A film was formed on the magnetic layer 8 by using tantalum as the material of the buffer layer 7 shown in FIG.
Here, the sputtering rate of tantalum with respect to the Ar ion energy of 500 eV is 0.57. The lattice constant is 0.306 nm.

The tantalum film to be the buffer layer 7 was formed by the sputtering method.

The carbon protective film 6 was formed on the buffer layer 7 by using the plasma CVD method. The film forming conditions are a mixed gas of argon and methane as a source gas, a film forming gas pressure of 0.1 Torr and a film forming voltage of 1000V.

Example 8 A film was formed on the magnetic layer 8 using silicon as the material of the buffer layer 7 shown in FIG. Here, the sputtering rate of silicon for Ar ion energy of 500 eV is 0.50. The crystal structure has a diamond structure.

The silicon film to be the buffer layer 7 was formed by the sputtering method.

The carbon protective film 6 was formed on the buffer layer 7 by using the plasma CVD method. The film forming conditions are a mixed gas of argon and methane as a source gas, a film forming gas pressure of 0.1 Torr and a film forming voltage of 1000V.

Example 9 Copper was used as the material of the buffer layer 7 shown in FIG. 3 to form a film on the magnetic layer 8. Here, the lattice constant of copper is 0.315 nm.

The copper film to be the buffer layer 7 was formed by the sputtering method.

The carbon protective film 6 was formed on the buffer layer 7 by using the plasma CVD method. The film forming conditions are a mixed gas of argon and methane as a source gas, a film forming gas pressure of 0.1 Torr and a film forming voltage of 1000V.

Example 10 Germanium was used as the material of the buffer layer 7 shown in FIG. 3 to form a film on the magnetic layer 8. Here, the crystal structure of germanium has a diamond structure.

The germanium film to be the buffer layer 7 was formed by the sputtering method.

The carbon protective film 6 was formed on the buffer layer 7 by using the plasma CVD method. The film forming conditions are a mixed gas of argon and methane as a source gas, a film forming gas pressure of 0.1 Torr and a film forming voltage of 1000V.

(Comparative Example 2) As Comparative Example 2, as shown in the cross-sectional view of the film in FIG. 4, the carbon protective film 9 was directly provided on the magnetic layer 10 (A1 ₂ O ₃ TiC) of the thin film head without providing the buffer layer. Was deposited.

The carbon protective film 9 was formed on the magnetic layer 10 by using the plasma CVD method. The film forming conditions are a mixed gas of argon and methane as a source gas, a film forming gas pressure of 0.1 Torr and a film forming voltage of 1000V.

The characteristics of the carbon protective films 1, 4, 6, 9 shown in the examples of FIGS. 1 and 3 and the comparative examples of FIGS. 2 and 4 will be described below.

First, the film formation rate of the carbon protective film will be described. Regarding the film forming rate, a value obtained by measuring the carbon protective film thickness and dividing by the film forming time was used. Note that the carbon protective film thickness was 2.5 μm by Talystep manufactured by Taylor-Hobson.
The measurement was performed using a stylus.

FIG. 5 shows a graph of the film-forming rate measurement results of each Example and Comparative Example. As can be seen from FIG. 5, the film formation rate is improved by using a material having a sputter rate of 1.0 or less as the buffer layer.

Next, the adhesion of the carbon protective film to the substrate will be described. In addition, for the adhesion measurement of the carbon protective film, a peeling load of the carbon protective film was measured using a scanning scratch tester SST101 manufactured by Shimadzu Corporation, and the value was used for evaluation.
Peel load measurement conditions are stylus curvature 15μm, scratch speed 20μm / s, amplitude 50μm, stylus pressing speed 1μ
m / s. FIG. 6 shows the results of measuring the adhesive force of each Example and Comparative Example. As can be seen from FIG. 6, the adhesion strength of the carbon protective film is improved by using a material having a lattice constant close to that of diamond for the buffer layer.

Next, the film quality of the carbon protective film will be described. Raman spectroscopic analysis was used to evaluate the film quality of the carbon protective film. 1550c due to the sp ² structure of the carbon film from the measurement results
The area intensity ratio sp ² / sp ³ of the peak around m to ^{1 and} the peak around 1400 cm to ¹ due to the sp ³ structure was determined, and the smaller this value was, the higher the diamond property was evaluated. Table 1 shows a list of film quality evaluation results of each example and comparative example.

[0069]

[Table 1]

As can be seen from Table 1, by using the material having the diamond structure as the buffer layers 2 and 7, the diamond property of the formed film is improved.

Next, the mechanical characteristics of the samples in which the carbon protective film was formed on each of the hard disk and the thin film head were evaluated. Mechanical properties were evaluated by a low speed sliding test. The low-speed sliding test is a test of the head and magnetic disk.
Sliding at 100 rpm for 1 hour, the amount of increase in friction coefficient δμk before and after sliding and the change in friction coefficient during sliding at 100 rpm are measured. The mechanical characteristics are judged to be good or bad by increasing the friction coefficient due to low speed sliding and observing the surfaces of the hard disk and thin film head after the test. As can be seen from Table 2, the evaluation results show that in the combination of the hard disk (a) having the buffer layers 2 and 7 and the carbon protective film formed thereon and the thin film head (a),
It exhibits excellent mechanical properties. On the other hand, with respect to a hard disk and a thin film head on which a carbon protective film is formed without providing a buffer layer, destruction due to peeling of the carbon film occurs at low speed sliding, resulting in poor mechanical properties.

[0072]

[Table 2]

Table 2 shows the results of evaluation of mechanical properties when tantalum was used as the material of the buffer layers 2 and 7, but similar results were obtained for the other examples.

As described above, according to this embodiment, by using a certain specific material for the buffer layer, it is possible to improve the deposition rate of the carbon protective film, the adhesion to the substrate, and the diamond property.

[0075]

As described above, the magnetic device of the present invention has the first magnetic layer, and the first buffer layer provided on the sliding surface side of the first magnetic layer with the medium. And a thin film magnetic head having a first carbon protective film provided on the first buffer layer, and a second magnetic layer on a substrate. a second buffer layer provided on the sliding surface side of the thin film magnetic head of the second magnetic layer, a second carbon <br/> containing protective film provided on the second buffer layer And a magnetic disk having: a magnetic disk having the first and second buffer layers in the same portion.
And the first and second carbon protective films are the same member
And the first and second buffer layers have T
Since it contains at least one of a, Si, Ti, Mo, Cu, and Ge, the carbon protective film is not destroyed even when they slide on each other, and has good friction and wear characteristics.

[0076]

[0077]

[Brief description of drawings]

FIG. 1 is a film cross-sectional view showing the basic structure of a hard disk in an embodiment of the present invention.

FIG. 2 is a film cross-sectional view showing a configuration as Comparative Example 1.

FIG. 3 is a film cross-sectional view showing the basic structure of a thin film head in an example of the present invention.

FIG. 4 is a film cross-sectional view showing a configuration as a comparative example 2.

FIG. 5 is a diagram showing a graph of measurement results of a deposition rate of a carbon protective film.

FIG. 6 is a diagram showing a graph of a result of measuring the adhesion strength of a carbon protective film.

[Explanation of symbols]

1, 4, 6, 9 ... Carbon protective film, 2, 7 ... Buffer layer, 3, 5 ... Hard disk magnetic layer, 8, 10 ... Thin film head magnetic layer.

Front page continuation (58) Fields surveyed (Int.Cl. ⁷ , DB name) G11B 5/62-5/82 G11B 5/84

Claims (2)

(57) [Claims] [Claim 1 further comprising a first magnetic layer, a first buffer <br/> over layer provided on the sliding surface side of the medium in the first magnetic layer, the first buffer layer First provided on the
A thin-film magnetic head and a carbon protective film, a second magnetic layer on the substrate, a second <br provided on the sliding surface side of the thin film magnetic head of the second magnetic layer A magnetic disk having a buffer layer and a second carbon protective film provided on the second buffer layer, wherein the first and second buffer layers are Same member
The first and second carbon protective films are the same member, and the first and second carbon protective films are
And the second buffer layer are made of Ta, Si, Ti,
A magnetic device containing at least one of Mo, Cu, and Ge. 2. The magnetic device according to claim 1, wherein the carbon protective film is formed by using a plasma CVD method.