JPH03108125A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To increase coercive force and S/N by forming a base film of specified thickness while applying voltage on a substrate, and then forming a magnetic film while applying voltage on the base film. CONSTITUTION:The base film 8 comprising Cr is formed by sputtering while -300V DC voltage to the sputtering device is applied on the substrate 1 covered with a Ni-P film 2. The base film 8 is made 100 - 1,000Angstrom thick. The magnetic film 9 comprising Co-Ni-Cr magnetic material is then formed by sputtering while -300V DC voltage to the sputtering device is applied on the substrate 1, film 2, and film 8. Further a Cr film 10 is formed on the magnetic film 9 and a protective film 5 thereon. By forming the base film 8 to <=1,000Angstrom thickness, reproduction output can be increased.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method of manufacturing a magnetic recording medium using Cr for the underlayer and a CO-based magnetically resistant material for the magnetic film.

Prior Art FIG. 6 is a perspective view showing a conventional magnetic recording medium. 6th
In the figure, 1 is a substrate made of aluminum alloy, 2 is a substrate 1
N1-P film formed by plating on top of N1
- The surface of the P film 2 is mirror-finished and then textured. Reference numeral 3 denotes a base film formed on the substrate 1 to a thickness of 1500 Å, and the base film 3 is made of Cr. 4
is a magnetic film formed on the base film 3 to a thickness of 600 mm,
The magnetic film 4 is made of a Co-Ni-Cr magnetic material. Reference numeral 5 denotes a protective film formed on the magnetic film 4 to a thickness of 200 Å, and the protective film 5 is made of carbon. This time, the base film 3 used a Co-Ni-Cr based magnetic material for the magnetic film, so the film thickness was set to 1500A. However, if a Co-Cr-Ta based magnetic material was used for the magnetic film, the base film 3 Film thickness 100OA
I was doing it.

In recent years, the capacity of magnetic recording media has been increased in order to miniaturize disk drives. The methods currently being numerically advanced to achieve this larger capacity include improving areal density by narrowing the distance between tracks of magnetic recording media, and improving linear density by narrowing the distance between bits. However, there has been a problem in that as the areal density and linear density of the magnetic recording medium are improved, the reproduction output becomes smaller.

In order to solve this problem, progress is being made in the development of magnetic recording media in which the magnetic film has a larger coercive force and the reproduction output does not decrease even if the areal density and linear density are improved. FIG. 7 shows a partial cross-sectional view of another magnetic recording medium.

In FIG. 7, 1 is a substrate, 2 is an N1-P film, 3 is a base film, and 5 is a protective film, which have the same structure as the magnetic recording medium shown in FIG. 6 is composed of Cr and has a film thickness of 15
The base film 7 is a magnetic film formed on the base film 3. The magnetic film 7 is made of a Co--Ni--Cr magnetic material and has a thickness of 600. The difference between the magnetic recording medium constructed in this manner and the magnetic recording medium shown in FIG. 6 is the method of forming the magnetic film and its underlying film. The magnetic recording medium shown in FIG.
The base film 3 is formed on the substrate 1 on which the magnetic film 4 is formed, and the magnetic film 4 is formed on the base film 3 using a sputtering method or the like. However, the magnetic recording medium shown in FIG. A base film 6 is formed while applying a DC voltage to the P film 2 and the substrate 1,
Furthermore, while applying a predetermined DC voltage to the substrate 1, the N1-P film 2, and the base film 6, a magnetic film 7 is further formed on the base film 6 using a sputtering method or the like. The magnetic recording medium shown in FIG. 7 formed in this way has a much thicker coercive force than the one shown in FIG.
500A, a magnetic film 4 is formed on it using a Co-Ni-Cr magnetic material, and its coercive force is measured to be approximately 100A.
A base film 3 is formed by sputtering by applying a DC voltage of 1,300 volts to the substrate 1 and the N1-P film 2, and a DC voltage of 1,300 volts is applied to the base film 3, the N1-P film 2, and the substrate 1. Co-Ni-C by applying DC voltage
The magnetic film 7 is formed by sputtering an r-based magnetic material.
was formed and the coercive force was measured to be about 1600 oersted. It can be seen that when the base film and magnetic film are formed while applying a DC voltage to the substrate 1 etc. in this way, the coercive force increases. In the above case, the DC voltage applied to the substrate 1 etc. was set to 1,300 volts, but as the voltage increases to 400 volts and -500 volts, the coercive force increases accordingly.

Problems to be Solved by the Invention However, the magnetic film 7 produced while applying a DC voltage to the substrate has a large coercive force (possibly), but the noise ratio in the reproduced output of the magnetic film 7 becomes large.

In other words, the S/N ratio deteriorates. Therefore, when the magnetic head records or reproduces data, errors often occur and the reliability of the magnetic recording medium is impaired.

The present invention solves the above-mentioned conventional problems, and even if a magnetic film is formed while applying a DC voltage to the substrate, the S/N ratio can be increased while maintaining the coercive force larger than before. The object of the present invention is to provide a method for manufacturing a magnetic recording medium.

Means for Solving the Problem In order to achieve this objective, a base film is formed with a thickness of 100A or more and 1000A or less while applying a voltage to the substrate, and a magnetic film is formed on the base film while applying a voltage to the base film. has been established.

Effect: With this configuration, the grain size of the base film becomes smaller, so the grain size of the magnetic film formed thereon also becomes smaller, increasing the S/N ratio of the magnetic film formed on the base film. (can do.

Embodiment FIG. 1 is an enlarged sectional view showing a sectional view of a magnetic recording medium in an embodiment of the present invention. In Fig. 1, 1 is a substrate;
2 is an N1-P film, and 5 is a protective film, which are the same as the conventional structure. 8 is a base film formed on the N1-P film 3 and made of Cr, and the base film 8 is formed to have a thickness of 300 mm. Further, the base film 8 is the substrate 1 on which the N1-P film 2 is formed.
It is formed by sputtering while applying a DC voltage of 1,300 volts to a sputtering device. 9 is formed on the base film 8, and the CON 1-L
o Cr+(+) A magnetic film made of a magnetic material, and the magnetic film 9 is formed to have a film thickness of 600A. It is formed by sputtering while applying a DC voltage of volts. 10 is a Cr film formed on the magnetic film 9 to prevent the magnetic film 9 from being corroded. The recording medium has a very large coercive force, low noise, and a very large S/N ratio.The method of applying voltage to the substrate 1, the N1-P film 2, and the base film 8 will be explained below. The substrate 1 formed up to the N1-P film 2 is held on a moving substrate holding member, and a brush provided in the sputtering chamber is brought into contact with the substrate holding member.Then, a voltage of 1,300 volts is applied to the sputtering apparatus through the brush. Then, voltage can be applied to the substrate 1, etc.

Next, the relationship between the thickness of the base film and the coercive force of the magnetic recording medium of this example will be explained with reference to FIG.

In FIG. 2, the horizontal axis represents the thickness of the underlying film, and the vertical axis represents the coercive force of the magnetic film. For comparison, FIG. 3 shows the relationship between the thickness of the base film and the coercive force of a conventional magnetic recording medium in which the base film and magnetic film were formed without applying a DC voltage to the substrate. In FIG. 3, as in FIG. 2, the horizontal axis represents the thickness of the base film, and the vertical axis represents the coercive force. At this time, both the conventional magnetic film and the magnetic film of this book were formed with a film thickness of 600A using C0QON im Crho magnetic material. As can be seen by comparing these two, the coercive force of the magnetic recording medium of this example is the same as that of the substrate II! Above 1600A, it is constant at 1600 oersted, but below 500A it decreases rapidly. However, although the coercive force is rapidly decreasing, when the underlying film thickness is 10 OA, the coercive force is 1000 oersted, which is the same as the maximum coercive force of the conventional magnetic recording medium shown in FIG.

That is, it can be seen that sufficient coercive force can be obtained if the thickness of the base film is 100 A or more. The minimum film thickness of the base film is 1
The reason for setting the value to 00A is that if the film thickness is less than 100A, a stable Cr crystal structure cannot be obtained.

Next, the relationship between the thickness of the base film and the reproduction output of the magnetic recording medium will be explained using FIG. 4.

In FIG. 4, the horizontal axis represents the thickness of the base film, and the vertical axis represents the relative output value. At this time, the reproduction output when the thickness of the base film is 200A is taken as a reference. As can be seen from FIG. 4, the relative output value is the largest when the base film is about 30 OA. In conventional magnetic recording media, the thickness of the underlying film is 100 OA or more, although it varies somewhat depending on the material of the magnetic film.

However, in a magnetic recording medium in which the magnetic film and underlayer are formed with a voltage applied to the substrate as in this example, a larger relative output value can be obtained by setting the thickness of the underlayer to 1000A or less. I understand.

Next, the relationship between the thickness of the base film and the S/N ratio of the magnetic recording medium will be explained using FIG.

In FIG. 5, the horizontal axis represents the thickness of the base film, and the vertical axis represents the relative S/N ratio of the magnetic recording medium. At this time, the S/N ratio when the thickness of the base film is 200 OA is used as the standard. As can be seen from FIG. 5, a curve similar to the relationship between the thickness of the base film and the relative output value shown in FIG. 4 is drawn. That is, it can be seen that if the base film is set to 1000 A or less and a magnetic film is formed on the base film, the S/N ratio becomes larger than the conventional S/N ratio. Also, as can be seen from Figures 4 and 5, when comparing the relative output values when the base film thickness is 1500A and 500A, 500A is about 1 dB larger, but
The S/N ratio is 1.3 dB thicker. What this means is that normally if the output increases by 1 dB, the S
/N ratio also increases by 1 dB, but in this example, the S/N ratio is 1.
This has improved to 3dB. In other words, when the film thickness is from about 100A to about 1000A, the proportion of noise in the reproduced output is smaller than when the base film is formed over 1500A.In other words, the characteristics are very good. It is possible to create a magnetic recording medium.The reason why the characteristics are improved like this is that by forming a thin underlayer, the grain size of the underlayer becomes smaller, and the magnetic film formed on the underlayer becomes thinner. This is thought to be because epitaxial growth occurs with the same grain size as the underlying film, forming a fine magnetic film.

As described above, according to this embodiment, a voltage of -300 volts is applied to the sputtering device on the substrate 1 and the N1-P film 2, and then the base film 8 is formed with Cr to a thickness of 300 A. By forming a magnetic film on 1, Ni-P film 2, and base film 8 while applying a voltage of 1,300 volts to a sputtering device, a magnetic film with a large coercive force and a large S/N ratio (and magnetic The reliability of the recording medium can be improved.

In this example, the thickness of the base film was 300A, but as mentioned above, the thickness of the base film could be changed from 100A to 100A.
Even between A, the coercive force is thicker than before (and the S/N
The ratio can be increased. Although the voltage applied to the substrate etc. was set at 1,300 volts, it is not limited to this voltage. For example, the same effect can be obtained with -400 volts or 1,500 volts. Further, in this embodiment, a COQII Nizo Crlo magnetic material was used for the magnetic film, but the same effect can be obtained using a co-based magnetic material.

Effects of the Invention The present invention forms a base film with a thickness of 100A or more and 1000A or less while applying a voltage to the substrate, and then provides a magnetic film formed while applying a voltage to the base film on top of the base film. Since the grain size of the base film becomes smaller, the grain size of the magnetic film formed thereon also becomes smaller (this makes it possible to increase the S/N ratio of the magnetic film formed on the base film, thereby reducing the error rate. The reliability of the magnetic recording medium can be improved.

[Brief explanation of drawings]

FIG. 1 is a partial cross-sectional view of a magnetic recording medium in an embodiment of the present invention, FIG. 2 is a diagram showing the relationship between the base film and coercive force of the magnetic recording medium in this embodiment, and FIG. A diagram showing the relationship between the base film and coercive force of a conventional magnetic recording medium in which no voltage is applied to the substrate. Figure 4 is a diagram showing the relationship between the base film and relative output value. Figure 5 is a diagram showing the relationship between the base film and relative S. FIG. 6 is a partial cross-sectional view of a conventional magnetic recording medium, and FIG. 7 is a partial cross-sectional view of another conventional magnetic recording medium. 1... Substrate 2... N1-P film 5... Protective film 8... Base film 9... Magnetic film 10... ...Cr film Fig. 1

Claims (2)

[Claims] (1) A method for manufacturing a magnetic recording medium, comprising forming a base film on the substrate while applying a voltage to the substrate, and forming a magnetic film on the base film while applying a voltage to the base film, the method comprising:
A method for manufacturing a magnetic recording medium, characterized in that the thickness of the base film is 100 Å or more and 1000 Å or less. (2) The method for manufacturing a magnetic recording medium according to claim 1, wherein the base film is made of Cr and the magnetic film is made of a Co-based magnetic material.