JP3177716B2 - Method for manufacturing in-plane recording type magnetic recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a longitudinal magnetic recording medium, and more particularly, to a method of forming a base film on a non-magnetic substrate and forming a Co alloy film thereon. The present invention relates to a method of manufacturing an in-plane recording type porcelain recording body formed by epitaxially growing an alloy film.

[0002]

2. Description of the Related Art As an in-plane recording type magnetic recording material, for example, a nonmagnetic substrate made of aluminum
Forming a base film consisting of, then forming a Co alloy film on the base film, epitaxially growing the Co alloy film,
Further, an in-plane recording type magnetic recording body having a C protective film formed thereon is known. Since the in-plane recording type magnetic recording medium has a high coercive force, it is frequently used as a hard disk medium capable of high-density recording. In general, a sputtering method is known for forming these films on the in-plane recording type magnetic recording medium. Among them, a DC magnetron sputtering method is widely used because of a high film forming rate.

In order to form these Cr films and Co alloy films on a non-magnetic substrate, high power is applied to the cathodes of the respective targets by DC magnetron sputtering while moving the substrates to the front of each target, and the targets are formed. Sputter to form Cr film and Co alloy film on non-magnetic substrate
2. Description of the Related Art A pass-through film forming method of sequentially forming a protective film sequentially and widely is widely used.

[0004]

However, although the pass-through type film forming method is excellent in productivity, magnetic anisotropy occurs in the manufactured in-plane recording type magnetic recording medium.

The magnetic anisotropy causes, for example, non-uniform magnetic characteristics in an in-plane recording type magnetic recording medium due to non-uniformity of the incident angle of sputtered atoms during film formation. Performing recording / reproducing with a magnetic recording medium has a problem that the output voltage swells as shown in FIG.

An object of the present invention is to solve the above-mentioned problems and to provide a method of manufacturing an in-plane recording type magnetic recording medium having little magnetic anisotropy and modulation.

[0007]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventors have found that when forming a base film and a Co alloy film on a substrate, only the base film target is used.
Alternatively, when a high-frequency power is superimposed on a DC power applied to both the base film target and the Co alloy target to form a film by sputtering, a good in-plane recording type magnetic recording medium having very little magnetic anisotropy and modulation can be obtained. I found that.

The present invention has been made on the basis of the above-mentioned findings, and a method of manufacturing an in-plane recording type magnetic recording material according to the present invention comprises forming a base film on a non-magnetic substrate by a sputtering method, In a method of manufacturing a longitudinal recording magnetic recording body of a longitudinal recording type in which a Co alloy film is formed on a ground film and the Co alloy film is epitaxially grown, when an under film is formed, DC power and A high-frequency power is superimposed and applied to form a sputter film.

The underlayer target is Cr, Mo, W
Alone target or an alloy target containing these as a main component. In addition, the base film and / or C
In forming the o-alloy film, the film may be formed while applying a negative bias voltage to the substrate. Further, when forming a Co alloy film, a DC power and a high frequency power may be superimposed and applied to a Co alloy target to form a sputter film. Further, the ratio of the high-frequency power to the total power applied to the target may be 3% or more and 85% or less.

When a base film and a Co alloy film are formed on a nonmagnetic substrate, high-frequency power is superimposed on DC power as power applied to only the base film target or both the base film target and the Co alloy target. The reason for obtaining a good in-plane recording type magnetic recording medium having extremely small magnetic anisotropy and modulation when formed by sputtering is considered to be as follows. It is to be noted that a case where a base film formed on a substrate is a Cr film will be described as an example.

That is, first, in the underlying Cr film layer, C
When the r film is formed, Cr atoms fly from the target at various points on the substrate at various incident angles. The Cr atoms reaching the substrate perform a diffusion motion on the surface of the substrate due to the incident energy at the time of arrival, and eventually lose energy and are fixed to a certain portion on the substrate. After that, similarly
Atoms fly one after another, coalesce with Cr atoms on the substrate, and grow into gradually larger particles while repeating this coalescence. However, when a particle grows to a certain size or more, a shadowed portion on the back side of the particle with respect to the main incident direction, so-called shadowing, is formed. When shadowing starts to occur, a so-called shadowing effect occurs, in which the probability of Cr atoms coming to the back of the particles that have increased to some extent decreases. As a result, the shadowing effect is small at the particle position adjacent to the main direction of the Cr atom at right angles to the adjacent particle position, and the particles are easily united and connected. However, the shadowing effect is parallel to the main incident direction due to the shadowing effect. , Particles are likely to remain separated from each other. As described above, the connection of the Cr particles on the already grown substrate differs from the main direction of incidence of the Cr atoms that are sputtered and fly on the substrate between a certain direction and a direction perpendicular thereto.
The same is true for the Co alloy particles.

The difference depending on the direction of connection of these Cr particles and Co alloy particles causes anisotropy of the magnetic characteristics of the in-plane recording type magnetic recording medium, resulting in modulation. In other words, in order to prevent the modulation from occurring, it is necessary to eliminate the non-uniformity of the connection of the Cr particles and the Co alloy particles.

As is generally well known, when a plurality of targets to which high-frequency power is applied are arranged close to one another in a single vacuum film-forming sputtering apparatus, the target is applied to the cathode. The high-frequency waves interfere with each other, and the film thickness distribution may become non-uniform. In the case of a hard disk, in particular, the uniformity of the thickness of a Co alloy film formed on a base film is very important in terms of its characteristics.

Therefore, in production, C to form a Co alloy film is used.
It is better to use DC power as the power to be applied to the o-alloy target and use a method of superimposing high-frequency power on DC power as the power to be applied to the Cr target for forming the Cr film. In this case, the magnetic anisotropy,
Although the effect of reducing the modulation is slightly smaller,
Magnetic anisotropy and modulation are remarkably improved as compared with the conventional method in which both do not overlap. This is because the Co alloy particles generate shadowing during the formation of the Co alloy film, but the Co alloy film is epitaxially grown on the underlying Cr film as widely known, so that the underlying Cr particles are This is because if the superposition is almost random, the Co alloy particles epitaxially grown thereon will also be random.

[0015]

When a base film and a Co alloy film are formed on a substrate, an electric power obtained by superimposing high-frequency power on DC power is applied to only the cathode of the base film target or the cathodes of both the base film target and the Co alloy target. However, when the target is sputtered to form a film, the effective self-bias potential applied to the target increases and the ionization rate in the plasma becomes lower than when the target is sputtered to form a film with a cathode to which only DC power is applied. The average incident energy of the sputtered particles that increase and reach the substrate increases. Therefore, when the particles reach the substrate with low incident energy, the diffusion motion of the particles on the substrate surface becomes active when the particles enter with high energy,
The particles of the base film and the particles of the Co alloy film are also diffused on the surface of the shadowed portion. Therefore, the connection of the particles of the base film and the Co alloy particles becomes random, so that the magnetic anisotropy of the hard disk hardly occurs and the generation of the modulation can be suppressed. In addition, when a negative bias voltage is applied to the substrate during film formation, particles in the ionized plasma are accelerated by the bias potential, and the incident energy becomes higher, so that the occurrence of modulation can be further reduced. The coercive force of the resulting disk can also be increased.

[0016]

EXAMPLES Specific examples of the method for manufacturing an in-plane magnetic recording medium of the present invention will be described together with comparative examples.

Example 1 A film was formed by using a rectangular Cr (base film material) having a size of 18 inches in length and 5 inches in width, Co-12 at% Cr as a target.
Inter-back type vertical double-sided film forming sputtering with a total of six cathodes, each of which is provided with two targets of 2 at% Ta (Co alloy film material) and C (protective film material) so as to oppose each other on both sides. This was performed using an apparatus. Then the pressure of the vertical double-sided film-forming the sputtering device 1 × 10 ^- was evacuated to less than ⁶ Torr, Ar gas 5 × 10 ^- was introduced to ³ Torr. Cathode with Cr target attached (hereinafter C
1.0KW DC power and 50W
Power obtained by superimposing the high-frequency power (13.56 MHz), C
An o-alloy cathode is attached (hereinafter referred to as a Co-alloy cathode), a power obtained by superimposing 0.8 KW DC power and a 40 W high-frequency power (13.56 MHz), and a C-target attached cathode (hereinafter referred to as a C cathode). 3K
W DC power was respectively applied.

During discharge, an amorphous NiP-plated aluminum 3.5-inch substrate with a textured surface is transported between opposing targets at a transfer speed of 200 mm / m.
in, and while passing, Cr on both sides of the substrate
Film, Co—Cr—Ta film (hereinafter referred to as Co alloy film), C
A disk was formed by sequentially forming films in the order of films. The thickness of each film formed on the substrate is 1000Å for the Cr film and 50 for the Co alloy film.
0 ° and the C film were 300 °.

A disk on which a Cr film, a Co alloy film, and a C film were formed in this order on a substrate was taken out of a vertical double-sided film forming apparatus, and recording / reproducing characteristics and magnetic characteristics were measured.
The evaluation of the modulation in the recording / reproducing characteristics was based on the numerical value obtained by the following equation from the maximum value Emax and the minimum value Emin of the output from the reproduction output waveform (envelope) in one round of the disk (see FIG. 1).

[0020]

(Equation 1)

In the measurement of magnetic properties, the disk is transported during film formation at the leading position (0 ° position) and at the upper position (90 ° position) at each of the two positions from the disk radius of 35 mm to the size of 8 × 8 mm. Samples were cut out and the magnetic properties in the circumferential direction of each disk were measured by VSM, and the difference ΔH between the coercive force (Hc) at the 0 ° position and the 90 ° position was measured.
The non-uniformity of the magnetic characteristics in the disk was determined from c and the difference ΔTBr between the product of the film thickness and the residual magnetization (TBr).

The envelope in one round of the produced disk was measured by a magnetic disk recording / reproducing characteristic evaluation apparatus [Model RD-008, manufactured by National Computer Co., Ltd.], and the result is shown in FIG. FIG. 3A shows a hysteresis loop at a 0 ° position measured by a sample vibration magnetometer [Model BHV-3 manufactured by Riken Denshi Co., Ltd.].
The position hysteresis loop is shown in FIG. As a result, the modulation rate was 5.4%, the coercive force (Hc) at the 0 ° position was 1558 Oe, the product of residual magnetization (TBr) was 457 G · μm, and the coercive force (Hc) at the 90 ° position was 1578 Oe, product of remanent magnetization (TB
r) is 436 G · μm, the difference ΔHc of the coercive force (Hc) is 20 Oe, and the difference ΔTB of the product (TBr) of the remanent magnetization.
r was 21 G · μm.

Example 2 The power applied to the Cr cathode was a power obtained by superimposing a DC power of 0.8 KW and a high-frequency power (13.56 MHz) of 300 W, and the power applied to the Co alloy cathode was 0.64.
KW DC power and 240W high frequency power (13.56M
Hz) was used in the same manner as in Example 1 except that the power was superimposed. As a result of measuring the envelope of the produced disk by the same method as in Example 1, the modulation rate was 4.2%, and the hysteresis loops at the 0 ° position and the 90 ° position were measured by the same method as in Example 1. As a result, the difference ΔHc of the coercive force (Hc) is
25 Oe, the difference ΔTBr of the product of remanent magnetization (TBr) is 16 G ·
μm. Example 3 The power applied to the Cr cathode was a power obtained by superimposing a DC power of 0.88 KW and a high-frequency power (13.56 MHz) of 330 W, and the power applied to the Co alloy cathode was 0.7.
04KW DC power and 264W high frequency power (13.5
6 MHz) and a Cr film and C
A disk was manufactured in the same manner as in Example 2 except that a negative bias voltage of 300 V was applied to the substrate during the formation of the o-alloy film. The envelope of the manufactured disk was used in Example 1.
As a result, the modulation rate was 2.
The hysteresis loop at each of the 0 ° position and the 90 ° position was measured by the same method as in Example 1. As a result, the difference ΔHc in the coercive force (Hc) was 18 Oe, and the product of the residual magnetization (TBr). Was 10 G · μm. Comparative Example 1 The power applied to the Cr cathode was 1.04 KW DC power, and the power applied to the Co alloy cathode was 0.83 KW
A disk was manufactured in the same manner as in Example 2 except that the DC power was set as follows. The envelope of the produced disk was measured in the same manner as in Example 1, and the result is shown in FIG.
Further, the hysteresis loop at the 0 ° position was measured by the same method as in Example 1, which was shown in FIG.
The hysteresis loop at the ° position was measured in the same manner as in Example 1 and is shown in FIG. 6 (B). As a result, the modulation rate was 14.6%, the coercive force (Hc) at the 0 ° position was 1,524 Oe, and the product of residual magnetization (TBr) was 41.
The coercive force (Hc) at the 90 ° position is 1770 Oe, and the product of residual magnetization (TBr) is 451 G
Μm, and the difference ΔHc of the coercive force (Hc) is 24
6 Oe, the difference ΔTBr of the product of residual magnetization (TBr) is 35 G ·
μm.

Comparative Example 2 A disk was prepared in the same manner as in Example 2 except that the power applied to the Cr cathode was changed to a high frequency power of 1.7 KW and the power applied to the Co alloy cathode was changed to a high frequency power of 1.4 KW. Produced. The envelope of the produced disk was measured in the same manner as in Example 1, and the result is shown in FIG.
Further, the hysteresis loop at the 0 ° position was measured by the same method as in Example 1, and the result was shown in FIG.
The hysteresis loop at the ° position was measured in the same manner as in Example 1, and the result was shown in FIG. 8B. As a result of these,
The modulation rate is 73.4%, the coercive force (Hc) at the 0 ° position is 1310 Oe, and the product of residual magnetization (TBr) is
The coercive force (Hc) at the 90 ° position is 1440 Oe, and the product of residual magnetization (TBr) is 296 G · μm.
Μm, and the difference ΔHc of the coercive force (Hc) is 13
0 Oe, the difference ΔTBr of the product of residual magnetization (TBr) is 160 G ·
μm.

As is apparent from FIGS. 2, 5 and 7, and FIGS. 3, 6 and 8, it can be seen that the basis of the occurrence of the modulation of the hard disk is the non-uniformity of the connection of the particles of the film material. . In particular, when a hard disk is manufactured by forming a film on a substrate by a pass-through film forming method using a rectangular target, each of the disks is used when the main incident direction of particles from the target is 0 ° position and 90 ° position on the substrate. Since the main incident direction (that is, the direction having kinetic energy) of the sputtered particles is different when compared in the circumferential direction, the connection of Cr particles and Co alloy particles due to the shadowing effect at both positions is also different. .

Therefore, in order to reduce the modulation, the Cr incident on the substrate at the 0 ° position and the 90 ° position is so reduced that the difference in connection due to the shadowing effect is small.
It is effective to activate the surface motion (surface diffusion) of the particles or Co alloy particles on the substrate surface, and to randomize the direction in which the particles try to connect. It can be seen that for this purpose, the incident energy of the Cr and Co alloys incident on the substrate should be increased as much as possible.

In the first, second, and third embodiments of the present invention, the high-frequency power is superimposed on the DC power as the power applied to the cathode. Alternatively, unlike the case of Comparative Example 2 in which only the high frequency power is applied, the effective self-bias voltage applied to the target is increased, and the ionization rate in the plasma is increased, and the average of the sputtered particles reaching the substrate is increased. Incident energy increases. Further, when the high frequency power superimposed on the DC power is increased as compared with the first embodiment as in the second embodiment, the average incident energy of the sputtered particles reaching the substrate is further increased, and the modulation rate is reduced. Further, when a negative bias voltage is applied to the substrate during film formation as in Example 3, ionized Cr particles and Co alloy particles in the plasma are attracted to the bias potential of the substrate. It can be seen that the energy of each atom incident on the substrate is further increased and the modulation rate is further reduced.

As is generally well known, when a plurality of cathodes for performing high-frequency sputtering in a single vacuum film-forming sputtering apparatus are arranged in the vicinity, high-frequency interferences occur during sputtering. Abnormality occurs in the film thickness distribution formed on the substrate. This is the result of Comparative Example 2,
Specifically, the fact that a modulation having no symmetry occurs as shown in FIG.
It is apparent from (B) that the thickness of the Co alloy film is different. This is presumably because the high frequencies applied to the two pairs of cathodes opposed to each other interfered with each other, resulting in an abnormality in the thickness of the Co alloy film formed on the Cr film.

In the case of an in-plane recording type magnetic recording medium, the fluctuation of the magnetic characteristics with respect to the fluctuation of the thickness of the underlying Cr film is extremely gentle, but the fluctuation of the thickness of the Co alloy film formed on the underlying film is very small. In contrast, the magnetic properties of the medium change rapidly. Such anomalies in the film thickness distribution due to the interference of the high frequencies applied to the cathode do not always occur in the same manner. There is a need to avoid.

Example 4 Various disks were produced in the same manner as in Example 2 except that the ratio of the high frequency power to the total power applied to the Cr cathode and the Co alloy cathode was changed variously. The envelope of each of the manufactured discs was replaced with the first embodiment.
The modulation rate was determined from the result, and the result is shown as a curve A in FIG.

Example 5 The ratio of the high frequency power to the total power applied to the Cr cathode and the Co alloy cathode was changed variously,
Various disks were produced in the same manner as in Example 2 except that a negative bias voltage of 300 V was applied to the substrate during the formation of the r film and the Co alloy film. The envelope of each of the produced disks was measured in the same manner as in Example 1, and the modulation rate was determined from the result. The result is shown as a curve B in FIG.

Example 6 Various disks were produced in the same manner as in Example 2 except that the ratio of the high-frequency power to the total power applied to the Cr cathode was changed variously, and DC power was applied to the Co alloy cathode. did. The envelope of each of the produced disks was measured in the same manner as in Example 1, and the modulation rate was determined from the result. The result is shown as a curve C in FIG.

Example 7 The ratio of the high-frequency power to the total power applied to the Cr cathode was varied, DC power was applied to the Co alloy cathode, and a negative voltage of 300 V was applied to the substrate during the formation of the Cr film and the Co alloy film. Various discs were manufactured in the same manner as in Example 2 except that the bias voltage was applied. The envelope of each of the produced disks was measured in the same manner as in Example 1, and the modulation rate was determined from the result. The result is shown as a curve D in FIG.

As is apparent from FIG. 4, although there is a slight difference depending on whether a negative bias voltage is applied to the cathode and the substrate in which high-frequency power is superimposed on DC power, and whether or not a negative bias voltage is applied to the substrate.
The ratio of high-frequency power in the total power applied to the cathode is 3%
It can be seen that the modulation rate can be reduced within the range of 85%. In addition, although the effect of reducing the modulation rate is somewhat small, in consideration of productivity, workability, etc., high-frequency power is superimposed only on the power applied at the time of sputtering on the Cr target, and applied at the time of sputtering on the Co alloy target. It can be seen that the power may be only DC power.

Example 8 The electric power applied to the Co alloy cathode was only DC power of 0.83 KW, and the power was applied to the substrate only during the formation of the Cr film.
A disk was manufactured in the same manner as in Example 2 except that a negative bias voltage of V was applied. As a result of measuring the envelope of the produced disk by the same method as in Example 1, the modulation rate was 4.0%, and the hysteresis loops at the 0 ° position and the 90 ° position were formed by the same method as in Example 1. As a result, the difference ΔHc of the coercive force (Hc) was 65 Oe, and the difference ΔTB of the product (TBr) of the remanent magnetization.
r was 41 G · μm.

Example 9 The power applied to the Co alloy cathode was only DC power of 0.91 KW, and a negative bias voltage of 300 V was applied to the substrate only during the formation of the Co alloy film formed on the base film. A disc was produced in the same manner as in Example 2 except that the above procedure was performed. As a result of measuring the envelope of the produced disk in the same manner as in Example 1, the modulation rate was 5.8.
%, And the hysteresis loop at each of the 0 ° position and the 90 ° position was measured by the same method as in Example 1. As a result, the difference ΔHc in coercive force (Hc) was 63 Oe, and the product of residual magnetization (TBr) Was ΔGBr of 28 G · μm.

Example 10 A power applied to the Cr cathode was superimposed with a DC power of 0.88 KW and a high frequency power of 330 W, and a negative bias voltage of 300 V was applied to the substrate only during the formation of the Cr film. A disk was manufactured in the same manner as in Example 2 except for the above. As a result of measuring the envelope of the produced disk in the same manner as in Example 1, the modulation rate was 3.9%.
The hysteresis loop at each of the 0 ° position and the 90 ° position was measured in the same manner as in Example 1. As a result, the difference ΔHc in coercive force (Hc) was 55 Oe, and the product of the residual magnetization (TBr) was 55 Oe. The difference ΔTBr was 20 G · μm.

Example 11 A power applied to a Co alloy cathode formed on a Cr film was applied by superimposing a DC power of 0.704 KW and a high frequency power of 264 W, and was applied to the substrate only during the formation of the Co alloy film. 30
Example 2 except that a negative bias voltage of 0 V was applied.
A disk was produced in the same manner as in the above. As a result of measuring the envelope of the manufactured disk in the same manner as in Example 1, the modulation rate was 3.5%, and the hysteresis loops at the 0 ° position and the 90 ° position were formed in the same manner as in Example 1. As a result, the difference ΔHc of coercive force (Hc) was 70 Oe, and the difference ΔTB of product (TBr) of remanent magnetization.
r was 34 G · μm.

Example 12 A disk was manufactured in the same manner as in Example 2 except that a Mo target was used as a target for the underlayer. As a result of measuring the envelope of the manufactured disk by the same method as in Example 1, the modulation rate was 5.1%, and the hysteresis loops at the 0 ° position and the 90 ° position were formed by the same method as in Example 1. As a result of measuring
The difference ΔHc in coercive force (Hc) is 69 Oe, and the product of residual magnetization (T
The difference ΔTBr of Br) was 22 G · μm.

Example 13 A disk was manufactured in the same manner as in Example 2 except that a W target was used as a target of the underlayer. As a result of measuring the envelope of the produced disk in the same manner as in Example 1, the modulation rate was 5.8%,
The hysteresis loop at each of the 0 ° position and the 90 ° position was measured in the same manner as in Example 1. As a result, the difference ΔHc in the coercive force (Hc) was 88 Oe, and the product of the residual magnetization (TB
r) The difference ΔTBr was 30 G · μm.

Example 14 A disk was manufactured in the same manner as in Example 2 except that a Cr alloy target composed of Cr-2 at% Si was used as a target of the underlayer. As a result of measuring the envelope of the manufactured disk by the same method as in Example 1, the modulation rate was 4.9%, and the hysteresis loops at the 0 ° position and the 90 ° position were formed by the same method as in Example 1. Was measured, the difference ΔH of the coercive force (Hc)
c is 77 Oe, and the difference ΔTBr of the product of remanent magnetization (TBr) is 27
G · μm.

Example 15 Mo-20 at% Cr-2a was used as a target for the underlayer.
A disk was manufactured in the same manner as in Example 2 except that a Mo alloy target composed of t% Si was used. As a result of measuring the envelope of the manufactured disk by the same method as in Example 1, the modulation rate was 5.1%, and the hysteresis loops at the 0 ° position and the 90 ° position were formed by the same method as in Example 1. As a result, the difference ΔHc in coercive force (Hc) is 90 Oe, and the product of remanent magnetization (TBr)
Was 31 G · μm.

Example 16 W-20 at% Cr-2 at as a target of the underlayer
A disk was produced in the same manner as in Example 2 except that a W alloy target composed of% Si was used. As a result of measuring the envelope of the produced disk in the same manner as in Example 1, the modulation rate was 5.0%, and
As a result of measuring the hysteresis loop at each of the 0 ° position and the 90 ° position in the same manner as in Example 1, the coercive force (H
The difference ΔHc of c) was 79 Oe, and the difference ΔTBr of the product of residual magnetization (TBr) was 27 G · μm.

Example 17 A Cr alloy target composed of Cr-2 at% Si was used as a target of the underlayer, and a 0.88K Cr cathode was used as the Cr cathode.
A disk was fabricated in the same manner as in Example 2 except that a DC power of W and a high frequency power of 330 W were superimposed and applied, and a negative bias voltage of 300 V was applied to the substrate only during the formation of the Cr alloy film. did. As a result of measuring the envelope of the produced disk in the same manner as in Example 1, the modulation rate was 4.0%, and the 0 ° position and 90%
As a result of measuring the hysteresis loop at each position in the same manner as in Example 1, the difference ΔHc in coercive force (Hc) was 37.
The difference ΔTBr between the product of Oe and the residual magnetization (TBr) is 31 G · μ
m.

Example 18 A Cr alloy target composed of Cr-2 at% Si was used as a target for the underlayer, and a Co alloy formed on the underlayer was used.
The same as Example 2 except that a DC power of 0.704 KW and a high-frequency power of 264 W were superimposed and applied to the alloy cathode, and a negative bias voltage of 300 V was applied to the substrate only during the formation of the Co alloy film. A disk was prepared by the method. As a result of measuring the envelope of the produced disk in the same manner as in Example 1, the modulation rate was 5.5%,
The hysteresis loop at each of the 0 ° position and the 90 ° position was measured by the same method as in Example 1. As a result, the difference ΔHc in coercive force (Hc) was 80 Oe, and the product of the residual magnetization (TB
The difference ΔTBr in r) was 35 G · μm.

Example 19 A Cr alloy target composed of Cr-2 at% Si was used as a target for the underlayer, and a 0.88K Cr cathode was used as the Cr cathode.
W power and 330 W high frequency power are superimposed and applied, and 0.704 KW DC power and 2 W are applied to the Co alloy cathode.
A disk was prepared in the same manner as in Example 2 except that a high-frequency power of 64 W was superimposed and applied, and a negative bias voltage of 300 V was applied to the substrate during the formation of the Cr alloy film and the Co alloy film. . As a result of measuring the envelope of the manufactured disk in the same manner as in Example 1, the modulation rate was 2.8%, and the 0 ° position and 90 °
As a result of measuring the hysteresis loop of each position in the same manner as in Example 1, the difference ΔHc of the coercive force (Hc) was 210
e, the difference ΔTBr of the product of residual magnetization (TBr) is 13 G · μm
Met.

Example 20 As a Co alloy target for the upper film, Co-30 at% Ni-
A disk was manufactured in the same manner as in Example 2 except that a Co alloy target composed of 7.5 at% Cr was used.
As a result of measuring the envelope of the produced disk by the same method as in Example 1, the modulation rate was 4.0%, and the hysteresis loops at the 0 ° position and the 90 ° position were formed by the same method as in Example 1. As a result of measuring
The difference ΔHc in coercive force (Hc) is 38 Oe, and the product of residual magnetization (T
The difference ΔTBr of Br) was 20 G · μm.

Example 21 As a Co alloy target for the upper film, Co-10 at% Cr-
A disk was produced in the same manner as in Example 2 except that a Co alloy target composed of 12 at% Pt was used. As a result of measuring the envelope of the manufactured disk by the same method as in Example 1, the modulation rate was 4.8%, and the hysteresis loops at the 0 ° position and the 90 ° position were formed by the same method as in Example 1. As a result of measuring
The difference ΔHc in coercive force (Hc) is 81 Oe, and the product of residual magnetization (T
The difference ΔTBr of Br) was 18 G · μm.

Example 22 Co-30 at% Ni-
A disk was manufactured in the same manner as in Example 2 except that a Co alloy target composed of 7.5 at% Cr was used, and the power applied to the Co alloy cathode was DC power of 0.83 KW. As a result of measuring the envelope of the manufactured disk in the same manner as in Example 1, the modulation rate was 4.1%, and the respective hysteresis loops at the 0 ° position and the 90 ° position were formed in the same manner as in Example 1. As a result, the difference ΔHc in coercive force (Hc) was 29 Oe, and the difference ΔTBr in product (TBr) of residual magnetization was 30 G · μm.

Example 23 Co-30 at% Ni-
Using a Co alloy target consisting of 7.5 at% Cr, the power applied to the Co alloy cathode was set to 0.83 KW DC power, and the DC power of 0.88 KW was applied to the Cr cathode.
A disc was produced in the same manner as in Example 2 except that a high-frequency power of 30 W was superimposed and applied, and a negative bias voltage of 300 V was applied to the substrate only during the formation of the Cr film. As a result of measuring the envelope of the produced disk in the same manner as in Example 1, the modulation rate was 4.3%.
The hysteresis loop at each of the 0 ° position and the 90 ° position was measured by the same method as in Example 1. As a result, the difference ΔHc in the coercive force (Hc) was 50 Oe, and the product of the residual magnetization (TBr) was 50 Oe. The difference ΔTBr was 23 G · μm.

Example 24 A Cr alloy target composed of Cr-2 at% Si was used as a target of the underlayer, and a C alloy composed of Co-30 at% Ni-7.5 at% Cr was used as the Co alloy target of the upper film.
A disk was produced in the same manner as in Example 2 except that an o-alloy target was used. As a result of measuring the envelope of the manufactured disk in the same manner as in Example 1, the modulation rate was 4.3%, and the respective hysteresis loops at the 0 ° position and the 90 ° position were formed in the same manner as in Example 1. Was measured, the difference ΔHc in coercive force (Hc) was obtained.
Is 54 Oe, and the difference ΔTBr of the product of remanent magnetization (TBr) is 33 G
-It was μm.

EXAMPLE 25 A Cr alloy target composed of Cr-2 at% Si was used as a target of the underlayer, and a C alloy composed of Co-30 at% Ni-7.5 at% Cr was used as the Co alloy target of the upper film.
Using an o-alloy target, the power applied to the Co alloy cathode was set to 0.83 KW DC power, the DC power of 0.88 KW and the high-frequency power of 330 W were superimposed and applied to the Cr cathode, and the Cr alloy film was formed. 30 on substrate only in film
Example 2 except that a negative bias voltage of 0 V was applied.
A disk was produced in the same manner as in the above. As a result of measuring the envelope of the produced disk by the same method as in Example 1, the modulation rate was 4.0%, and the hysteresis loops at the 0 ° position and the 90 ° position were formed by the same method as in Example 1. As a result, the difference ΔHc of the coercive force (Hc) is 90 Oe, and the difference ΔTB of the product (TBr) of the remanent magnetization.
r was 16 Gm.

Example 26 A Cr alloy target composed of Cr-2 at% Si was used as a target of the underlayer, and a C alloy composed of Co-30 at% Ni-7.5 at% Cr was used as the Co alloy target of the upper film.
Using an o-alloy target, the power applied to the Co alloy cathode was set to a DC power of 0.91 KW, and a negative bias voltage of 300 V was applied to the substrate only during the formation of the Co alloy film formed on the base film. A disc was produced in the same manner as in Example 2 except that the above procedure was performed. As a result of measuring the envelope of the manufactured disk by the same method as in Example 1, the modulation rate was 5.7%, and the hysteresis loops at the 0 ° position and the 90 ° position were formed by the same method as in Example 1. Was measured, the difference ΔH of the coercive force (Hc)
c is 67 Oe, and the difference ΔTBr of the product of remanent magnetization (TBr) is 31
G · μm.

In the above embodiment, only the underlayer target was used.
Alternatively, the frequency of the high-frequency power superimposed on the DC power applied to both the base film target and the Co alloy target is set to 13.56 MHz. However, the present invention is not limited to this, and the frequency is from several kilohertz to several hundred megahertz. Any frequency that can increase the self-bias voltage of the cathode by superimposing the high-frequency power on the DC power or a frequency that can increase the ionization efficiency in the plasma may be used.

[0055]

According to the method of the present invention, the power applied to the target of the underlying film formed on the substrate is a power obtained by superimposing a high frequency power on a DC power. Energy of the underlayer particles on the substrate to promote the surface diffusion of the underlayer particles and reduce the non-uniformity of the connection of the underlayer particles. There is an effect that an in-plane recording type magnetic recording medium having a small number of recordings can be easily manufactured.

Further, if a film is formed while applying a negative bias voltage to the substrate during the formation of the base film or the / Co alloy film,
The energy of the particles incident on the substrate is further increased, and the surface diffusion can be further promoted, so that there is an effect of reducing the modulation.

When a DC power and a high frequency power are superimposed and applied to the Co alloy target when forming the Co alloy film on the under film, not only the connection of the particles of the under film is made random but also the Co Since the connection of the particles can be made at random, the connection of the particles becomes very uniform, which has the effect of reducing the modulation.

If the ratio of the high frequency power to the total power applied to the target is 3 to 85%, there is an effect that the modulation can be stably reduced.

[Brief description of the drawings]

FIG. 1 shows an example of an envelope of an in-plane recording type magnetic recording medium in which modulation has occurred.

FIG. 2 shows an envelope of an in-plane recording type magnetic recording medium prepared in one embodiment of the present invention;

FIG. 3 shows a hysteresis loop of an in-plane recording type magnetic recording medium prepared according to an embodiment of the present invention.
The hysteresis loop measured at the position, (B) the hysteresis loop measured at the 90 ° position of the disc,

FIG. 4 is a characteristic diagram showing a relationship between a modulation rate of a longitudinal recording magnetic recording medium and a ratio of a high-frequency power to a total power, according to another embodiment of the present invention.

FIG. 5 shows an envelope of an in-plane recording type magnetic recording medium prepared by a conventional method,

6A and 6B show a hysteresis loop of a longitudinal recording magnetic recording medium prepared by a conventional method, FIG. 6A shows a hysteresis loop measured at a 0 ° position on a disk, FIG. 6B shows a hysteresis loop measured at a 90 ° position on a disk,

FIG. 7 shows an envelope of an in-plane recording type magnetic recording medium prepared by another method according to the related art;

FIG. 8 shows a hysteresis loop of an in-plane recording type magnetic recording medium prepared by another method according to the related art.
Hysteresis loop measured at position, (B) Hysteresis loop measured at 90 ° position on disk.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Michio Ishikawa 523 Yokota, Yamatake-cho, Yamatake-gun, Chiba Japan Nippon Vacuum Engineering Co., Ltd. (72) Inventor Kafumi Ota 523 Yokota, Yamatake-cho, Yamatake-gun, Chiba Technology Co., Ltd. Chiba Super Materials Research Laboratory (72) Inventor Tadahiro Shiro 523 Yamatake-cho, Yamatake-gun, Chiba Prefecture Japan Vacuum Technology Co., Ltd. Chiba Super Materials Research Laboratory (56) References JP-A-2-161617 (JP, A) JP-A-2-162526 (JP, A) JP-A-63-300430 (JP, A) JP-A-3-249171 (JP, A) JP-A-2-574764 (JP, A) JP-A-63-140077 (JP) JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G11B 5/851 C23C 14/00-14/58

Claims (5)

(57) [Claims] An undercoat film is formed on a non-magnetic substrate by a sputtering method, and then a Co alloy film is formed on the undercoat film.
In the method of manufacturing an in-plane recording type magnetic recording medium formed by epitaxially growing an alloy film, a sputter film is formed by applying a DC power and a high frequency power to a base film target in a superimposed manner when forming a base film. Of manufacturing an in-plane recording type magnetic recording medium. 2. The in-plane recording type porcelain recording body according to claim 1, wherein the underlayer target is a single target of Cr, Mo, or W, or an alloy target containing these as main components. Production method. 3. The in-plane film according to claim 1, wherein the film is formed while applying a negative bias voltage to the substrate during formation of the base film and / or the Co alloy film. A method for manufacturing a recordable magnetic recording medium. 4. The method according to claim 1, wherein when forming the Co alloy film, a DC power and a high-frequency power are applied to the Co alloy target in a superimposed manner to form a sputter film.
Item 13. The method for producing an in-plane recording magnetic recording medium according to any one of the above items. 5. The surface according to claim 1, wherein the ratio of the high-frequency power to the total power applied to the target is not less than 3% and not more than 85%. Method for manufacturing an inner recording type magnetic recording medium.