JPH02126424A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve coercive force by impressing the potential which is positive with respect to a substrate and the grounding part of a device body to an intermediate electrode of a prescribed shape provided near a target to form a thin magnetic film. CONSTITUTION:The substrate 3 is mounted on the substrate holder 3 facing to the target 1. The intermediate electrode 4 having the shape to enclose at least 1/2 the outer peripheral part of a sputter erosion part 7 is installed near the target 1. An alloy which consists essentially of Co and consists of Cr and Ta is adequate as the target 1. The potential which is positive with respect to the substrate 2 and the grounding part of the device body, more preferably 50 to 500V, further preferably 100 to 400V potential is impressed to the intermediate electrode 4 and sputtering is executed in this state, by which the thin magnetic metallic film is formed on the substrate 3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method of manufacturing a magnetic recording medium, and more particularly, to a method of manufacturing a magnetic recording medium having a high coercive force.

[Conventional technology]

In recent years, with the development of information processing technology such as combinators, there has been an increasing demand for high-density recording in magnetic recording media such as magnetic disks used in external storage devices.

Currently, as the magnetic layer of a magnetic recording medium used in a magnetic disk for longitudinal recording, a Co-based alloy thin film epitaxially formed on a Cr underlayer thin film by sputtering or the like has become mainstream. However, regarding this Co-based alloy thin film magnetic layer, in response to the demand for higher density recording,
It is necessary to impart higher coercive force as a magnetic property, and there have been many reports regarding this property. (For example, “New longit
udinal recording media co
x Niy Crz from high rate 5
tatic magnet-ron sputteri
ng system, IEEE Trans.

Magn, Mag-x Co., No&, (198), 3J
II; JP-A No. 7-7?233; JP-A-63
-7296g publication. ) [Problems to be Solved by the Invention] As previously reported, the coercive force of a Co-based alloy thin film magnetic layer increases with the thickness of the Cr underlayer thin film. However, when a certain upper limit is exceeded, saturation characteristics are exhibited, and it is difficult to increase the coercive force further. For example, JP-A-1.3-
Publication No. 7991.8 states that the thickness of the Cr underlayer thin film is /
It has been shown that above j 00 A, there is a tendency for the coercive force of the magnetic layer to not increase any further, and below that, the coercive force of the magnetic layer decreases significantly, posing a practical problem.

Moreover, this coercive force increases as the thickness of the CO-based alloy thin film is reduced. However, since reducing the film thickness leads to a decrease in the reproduction output value, it is practically difficult to reduce the film thickness to a predetermined thickness or less. Further, although it is possible to improve the coercive force to some extent by selecting sputtering conditions such as the deposition gas pressure and substrate temperature during deposition of the magnetic layer, the improvement effect is small.

Additionally, a method of sputtering with a negative bias voltage applied to the substrate is also known as a method of improving the coercive force of the magnetic layer. , 29a-c-?
, 10) However, in a continuous film forming apparatus in which the substrate moves, the apparatus becomes complicated in order to apply a negative potential to the moving substrate, and it is necessary to apply the negative potential not only in the vicinity of the target but also in a wide range. As a result, there are various problems as an industrial film forming method, such as abnormal discharge occurring and leading to damage to the film forming apparatus.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems and provide a method for manufacturing a magnetic recording medium having an extremely high coercive force.

[Means for solving the problem]

In view of the above-mentioned conventional situation, the inventors of the present invention have made extensive studies to further improve the coercive force of magnetic recording media. As a result, the inventors have provided an intermediate electrode near the outer periphery of the target, and attached the substrate and film forming apparatus to the intermediate electrode. By sputtering a specific magnetic alloy thin film, that is, a magnetic metal thin film mainly composed of cobalt, on the substrate while applying a positive potential to the grounding part of the main body, the coercive force of the magnetic recording medium can be significantly increased. The present inventors have discovered that the present invention can be improved.

That is, the gist of the present invention is to provide a method for manufacturing a magnetic recording medium in which a cobalt-based alloy magnetic thin film is formed on a substrate by sputtering, in which at least 1/2 of the outer periphery of the sputter erosion region of the target is formed near the target. A method for manufacturing a magnetic recording medium, comprising: providing an intermediate electrode having a surrounding shape, and forming a cobalt-based alloy magnetic thin film while applying a positive potential to the intermediate electrode with respect to a grounded portion of a substrate and a main body of a film forming apparatus. exists in

Hereinafter, the present invention will be explained in detail.

The substrate used in the present invention is generally a disk-shaped substrate made of metal, particularly aluminum or aluminum alloy. Usually, after processing an aluminum substrate to a predetermined thickness, the surface is mirror-finished and a first A hard non-magnetic metal such as an N1-P alloy is formed as the next underlayer by electroless plating or anodizing, and then Cr is sputtered as the first underlayer. As a substrate, Cr was used as an underlayer directly on a mirror-finished aluminum substrate without forming the seventh underlayer.
It is also possible to use a material obtained by sputtering.

There are no particular restrictions on the sputtering conditions for forming the Cr underlayer, and any sputtering conditions that are employed when forming a normal Cr underlayer can be employed.

The method for forming this magnetic thin film will be described in detail below with reference to the drawings.

FIG. 1 is a schematic diagram showing an example of a sputtering apparatus used for carrying out the present invention. In the figure, l is a target, a substrate holder 2 is provided at a position opposite to this, and a substrate 3 is mounted on the substrate holder. The substrate holder is movable so that the substrates 3 can be deposited continuously. An intermediate electrode q is installed in a shape that surrounds the sputter discharge space between the target l and the substrate, more specifically, in the vicinity of the target l, and has a shape that surrounds at least IA of the outer periphery of the sputter erosion end of the target l. . 5 is a sputtering power supply connected to the target l and the intermediate electrode l.

Reference numeral 6 denotes an intermediate electrode power source connected to the grounding part of the main body of the film forming apparatus and the intermediate electrode. 7 shows the sputter erosion part of target l.

As the sputtering power source and the intermediate electrode power source 6, a DC power source is preferable, but an RF power source can also be used.

As the sputtering device, a normal DC magnetron sputtering device or an RF magnetron sputtering device is employed.

FIG. 2 is a detailed view of the sputtering apparatus of FIG. 7.

1 is the magnetron magnet, 1 is the cathode of the DC magnetron, IO is the main body of the film forming apparatus, and /l is the grounding part of the main body io of the film forming apparatus.

FIG. 3 is a part of a cross-sectional view showing an example of the position and shape of the intermediate electrode, and (A) to (F) are all at least 172 mm on the outer periphery of the sputtering end of the target l.
It is said to have a shape that surrounds the above.

The intermediate electrode has a distance of 1/3, preferably 1, of the distance between the target surface and the substrate in the direction of the substrate with the target surface as a reference.
at least a part thereof is provided within a range of 701m5, preferably 0Im away from a position opposite to the substrate with respect to the target surface,
And, with respect to the planar direction of the target, from the outer periphery of the end of the spatter erosin of the target to the outer periphery of the target using the outer periphery as a reference: 110Ox preferably /!
;Om, more preferably /20n away, and the sputter erosion edge of the target is provided in a range that surrounds a small part (both 1/2, preferably the entirety of the outer periphery of the target) of the sputter erosion end of the target. In particular, the intermediate electrode extends from a position of 3θm in the direction of the substrate with the target surface as a reference, and s in the direction opposite to the substrate with the target surface as a reference.
It is preferable that it be provided in such a way as to surround the entire outer periphery of the target within a range of up to 1201 m1 in the outward direction from the outer periphery of the target to the oH position and from the outer periphery of the target. .

If the position of the intermediate electrode is outside the above range, the effect of improving the coercive force of the magnetic recording medium will be significantly reduced, which is not preferable.

Further, the shape of the intermediate electrode is a shape that surrounds at least 1/2 of the outer circumference of the target l, for example, a ring shape, a cylindrical shape,
A plate shape or the like is used. If the intermediate electrode surrounds less than 1/2 of the outer periphery of the target layer, the effect of improving the retaining force will be reduced, which is not preferable.

Furthermore, metals such as stainless steel, aluminum, and copper are usually used as the material for the intermediate electrode.

The sputter erosion edge of a target refers to the boundary line formed between the area where the target material is sputtered (sputter erosion area) and the area where it is not sputtered when the target surface is sputtered. . In the present invention, the outer periphery of this boundary line is defined as the outer periphery of the end of the sputtering region of the target. In the case of a flat target, the sputter erosion part forms a ring shape having an inner circumference and an outer circumference, and this outer circumference is referred to as the outer circumference of the sputter erosion end in the present invention. The position of the sputter erosion part is determined by the size of the target and the arrangement of the magnetron magnet. In addition, in the case of a sputtering device in which the target surface is covered with a shield plate, the position of the end of the vine erosion is determined by the size of the shield plate.

As target I, Co-Cr, Co-Cr-X
%Co-N1-X, Co-W-X, etc., a CO-based alloy whose main component is CO is used. Here, X is Li, Si, B, Ca, Ti, V, Cr, Ni, As
, Y, Zr%Nb%Mo, Ru.

Rh, Ag, Sb, Hf, Ta, W, Re, Os.

Ir, Pt, Auv, La, Ce, pr, Nd, Pm.

One or more elements selected from the group consisting of Sm and Eu are used.

As the target l, an alloy containing CO as a main component and consisting of Cr and Ta is preferably used.

As this Co-Cr-Ta alloy, CO: RiO~93
atomic %, Cr", !r~Co0 atomic % and Ta: 0.1-
A composition of io atomic % is preferred.

In order to manufacture a magnetic recording medium according to the method of the present invention using the sputtering apparatus shown in FIG. Sputtering is carried out in the presence of a rare gas such as Ar, using an electrode that is positive with respect to the substrate and the grounding part of the sputtering apparatus main body, for example, 1000 mm or less, preferably g
Sputtering is performed while applying an o-soov potential, more preferably an ioo to qoov potential, to form a magnetic metal thin film of a CO-based alloy on the substrate 3.

In the present invention, the sputtering conditions are usually as follows:
Conditions employed when forming a magnetic layer of a magnetic recording medium can be employed.

For example, the pressure inside the evacuated chamber is /xIO-'
Below TOrr, rare gas pressure such as Ar is 0! X/0
-” ”-2X/0-” Torr, preferably tx/0-3~!rx/0-” Torr
Sputtering can be carried out under conditions where the substrate temperature is in the range of 10° C. or more, preferably in the range of 00° C. to 300° C.

The thickness of the magnetic alloy thin film layer formed by such sputtering is such that the product (Br-t) of the residual magnetic density (Br) and the film thickness (1) of the magnetic alloy thin film layer is 30θ to 700G.
It is preferable to set the film thickness to .mu.m.

1 to 13 are schematic diagrams and detailed diagrams showing other examples of sputtering equipment suitable for carrying out the present invention.

[For production]

An intermediate electrode is provided near the outer periphery of the target, and a magnetic metal thin film layer of a CO-based alloy is formed by sputtering with a positive potential applied to the ground part of the main body of the film forming apparatus, which is the intermediate electrode, to achieve high retention. A high quality magnetic recording medium having magnetic force is formed.

〔Example〕

EXAMPLES The present invention will be described in more detail below with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples unless it exceeds the gist thereof.

In addition, in the following Examples and Comparative Examples, the symbols a to e are given in the drawings to specify the positions and shapes of the intermediate electrodes. b indicates the distance from the outer periphery of the target to the intermediate electrode; in the following Examples and Comparative Examples, the end of the sputtering tube of the target and the outer periphery of the target are the same part, so b is the distance from the outer periphery of the target. The distance from the outer periphery of the sputter erosion end to the intermediate electrode is shown.

Note that in the apparatus used in the example, the substrate holder 2 is grounded via the film forming apparatus main body io.

Examples 1 to 7, Comparative Example 1 Using the equipment shown in Figures 1 and 2, C was used as the base layer.
An aluminum substrate on which r thin film was formed and (o-Cr
- Using a Ta alloy target l, with a positive potential shown in Table 1 applied to the intermediate electrode t with respect to the substrate, and A
Ultimate pressure in the chamber in the presence of r gas/X/0
-' Torr or less, argon gas pressure II
Sputtering was performed under the conditions of 0-3 Torr and substrate temperature of 10°C, and a t6 atomic % Co-/2 atomic % Cr - J atomic % Ta magnetic layer (1100 G μm) was formed on the substrate.
was formed. Table 1 shows the results of measuring the coercive force of the obtained magnetic disk using a sample vibrating magnetometer.

From the examples, it has been found that when sputtering is performed with a positive potential applied to the intermediate electrode with respect to the substrate, the coercive force of the resulting magnetic disk is significantly improved.

*) Intermediate electrode position and shape a=/! rB, b=! r 0vrx, c=52m
s, d==Jmi.

e=g3footl Shape: Shape that surrounds the entire outer periphery of the target Using a device* shown in Examples g to 12 and Comparative Examples in Figures 9 and S of the table, a Cr thin film (thickness 100A) was used as an underlayer. ) formed by sputtering, and an aluminum substrate 3 formed by sputtering Co-Cr-T.
Using a alloy target /, intermediate electrode lIK, substrate 3
Sputtering is carried out under the conditions of the chamber internal ultimate pressure/xlθ-" Torr, argon gas pressure x/0-" Tour, and substrate temperature of 230° C. while applying the potential shown in Table 1 to A 6 atomic % Co - / 2 atomic % Cr - Co atomic % Ta magnetic layer (kkOQ·μm) was formed on the substrate.

The coercive force of the obtained magnetic disk was measured using a sample vibrating magnetometer, and the results are shown in Table 1.

*) Intermediate electrode position and shape a ” J m1ll + 1) =j Inn, C
"3 III s d" Q j m1ll ee=
ffj door 1 Shape: Forming tube surrounding the entire outer periphery of the target 2 Table Example/J-/Za, Comparative example 3 The apparatus shown in FIG. 6 was used, and a thin Cr layer (
Using an aluminum substrate 3 on which a film thickness of tooA) was formed by sputtering and a Co-Cr-Ta alloy target l, a potential shown in Table 3 was applied to the intermediate electrode q with respect to the substrate 3, and a chamber was heated. Ultimate pressure/X
t O-' Torr or less, argon gas pressure car X1
Sputtering is performed under conditions of 0""" Torrs and a substrate temperature of 0°C, and 6 atomic% Co-/λ is deposited on the substrate.
atomic% Cr -2 atomic% Ta magnetic layer<ss; oa・μm
) was formed.

The coercive force of the obtained magnetic disk was measured using a sample vibrating magnetometer, and the results are shown in Table 3.

*) Intermediate electrode position and shape a=7m, b=4v, x, c=7/rnx,
d==/00ratt.

e=rJ wing shape; shape that surrounds the entire outer periphery of the target Table Examples 19-20. In the comparative example, the apparatus shown in FIG. 7 was used, and a Cr thin film (
an aluminum substrate 3 on which a film thickness of 1000k) was formed;
Intermediate electrode q using Co-Cr-Ta alloy turf/
When the potential shown in Table 9 is applied to the chamber, the pressure inside the chamber is less than /
Sputtering was performed under conditions of 0-'' Torr and a substrate temperature of 230°C, and t6 atomic% Co-/2 atomic% was deposited on the substrate.
A Cr-Co atomic % Ta magnetic layer (jjOG·μm) was formed.

The coercive force of the obtained magnetic disk was measured using a sample vibrating magnetometer, and the results are shown in Table 1.

*) Intermediate electrode position and shape a=Jmm, b=/02H, c=! ;gem, d
=, 7mm.

e=ffjm Shape: Shape q that surrounds the entire outer periphery of the target
Table case 21 - Here is a comparative example! Using the apparatus shown in FIG. 3, an aluminum substrate 3 and C were formed with a Cr thin film (thickness: 1000 mm) as an underlayer by sputtering.

- Using a Cr-Ta alloy turf/, with the potential shown in Table 5 applied to the intermediate electrode 3 with respect to the substrate 3,
The ultimate pressure in the chamber is l x 10'Torr or less, the argon gas pressure is xio-'Torr, and the substrate temperature is 30'Torr.
Sputtering was carried out under the conditions of
oa・μm) was formed.

The coercive force of the obtained magnetic disk was measured using a sample vibrating magnetometer, and the results are shown in Table 3.

*) Intermediate electrode position and shape a=3xx, b=jm, c==jgmm, d=100m
.

-43mm Shape: Shape surrounding the entire outer periphery of the target Table Examples 23 to 25, Comparative Example 6 Using the apparatus shown in FIG. 3 and C0-Cr-Ta alloy turf/
With the potential shown in Table 6 applied to the substrate 3 at the intermediate electrode, the ultimate pressure in the chamber is l×10.
-'Torr or less, fluid pressure axio-'
Sputtering was performed under the condition of a TOrrs substrate temperature of 250°C, and g6 atomic% Co-1; 1 atomic% Cr was deposited on the substrate.
A Ta magnetic layer (61 G·μm) was formed.

The coercive force of the obtained magnetic disk was measured using a sample vibrating magnetometer, and the results are shown in Table 6.

*) Intermediate electrode position and shape a=/7rrm, b=/Om, c=/Jmx
, d=/ Juts.

e=g3m Shape; Example 31; Shape surrounding 601/2 of the outer periphery near the target Table Example 26, Comparative Example 7 Using the device* shown in Figure io, a Cr thin film (thickness toook) was used as the underlayer. Using an aluminum substrate 3 formed by sputtering and a C0-Cr-Ta alloy turf, the ultimate pressure in the chamber l was applied to the intermediate electrode with the potential shown in Table 7 applied to the substrate 3. ×
10' Torr or less, Argos gas pressure 10
Sputtering was performed under the conditions of -3 Torr and a substrate temperature of 230°C, and 6 Ryoko%Co-/2 atomic%C was formed on the substrate.
An r-Co atomic % Ta magnetic layer (RkOG/μm) was formed.

The coercive force of the obtained magnetic disk was measured using a sample vibrating magnetometer, and the results are shown in Table 7.

*) Intermediate electrode position and shape a= / , 71m, b=6 Jmx, c=jva
, d=-tλmX.

e=g3. A shape that surrounds the entire lower outer periphery of the target Table Comparative Examples
Aluminum substrates 3 and C formed by sputtering to have a film thickness of tooA).

- Intermediate electrode using Cr-Ta alloy turf/
K % When the potential shown in Table g is applied to the substrate 3, the ultimate pressure in the chamber is l x 10-' TOrr or less,
Argon gas pressure 2XlO-”Torr, substrate temperature!
! Sputtering is performed under the condition of 0 °C, and g6 atomic % Co-/: atomic % Cr-2 atomic % T is deposited on the substrate.
A magnetic layer (rto .mu.m) was formed.

The coercive force of the obtained magnetic disk was measured using a sample vibrating magnetometer, and the results are shown in Table 1.

*) Intermediate electrode position and shape a=/ 7m+11+ l)=/ Otrm, c=/
3 friends, d=/Jmx.

e=tJ base shape; near the outer periphery of the target, 3O1/2 of the outer periphery
Shape surrounding t Table Examples 27-2t, Comparative Examples 1o-l/Using the apparatus used in Examples, a Cr thin film (
Using an aluminum substrate 3 on which a film thickness of 2,000 mm) was formed by sputtering and a Co-based alloy target l shown in Table 9, a potential shown in Table 7 was applied to the intermediate electrode Hiroshi with respect to the substrate 3. So, the ultimate pressure in the chamber l
×'O'Torr or less, argon gas pressure 2X/0
- Sputtering was performed under the conditions of "Torr" and a substrate temperature of 230°C, and a magnetic layer (jjO
G・μm) was formed.

The coercive force of the obtained magnetic disk was measured using a sample vibrating magnetometer, and the results are shown in Table 7.

Table t Example 29-. 71I, Comparative Examples 12~/4' Using the apparatus shown in Figure 1*), a Cr thin film (thickness: o
ooA) and the aluminum substrate 3 formed with Co-C
The intermediate electrode was used on the r-Ta alloy target.
With the potential shown in the table applied, the chamber pressure/
X#7-'Torr or less, argon gas pressure x 1O-
Sputtering was performed under conditions of 3 Torr and a substrate temperature of 230°C, and t6 at.% CO-/2 at.% Cr was deposited on the substrate.
-2 atoms XTa magnetic layer (HiroOOa/μm) was formed.

The coercive force of the obtained magnetic disk was measured using a sample vibrating magnetometer, and the results are shown in Table 10.

*) Intermediate electrode position and shape a=/m, b=/mm, (H=jH1, d==j
Atran.

e=200 cylindrical shape; shape that surrounds the entire outer periphery of the target Example 3
3-3 Hiro, Comparative Examples 15-/6 The same procedure as in Example 29 was carried out except that the Co-Cr-Ta alloy was changed as shown. The results are shown in Table io.

Table O Example 3! An aluminum substrate 3 on which a Cr underlayer (film thickness 20OA) was formed as an underlayer by sputtering using an RF magnetron sputtering apparatus*) shown in FIG.
Using the o-Cr-Ta alloy target, and applying the potential shown in Table 11 to the substrate 3 to the intermediate electrode, the ultimate pressure in the chamber was 1 x 10-'Torr or less,
Argon gas pressure 2 x / 0-” Tor r s
Sputtering was performed at a substrate temperature of 230° C. to form a magnetic layer of 4i % Co − / 2 atomic % Cr − 2 atomic % Ta (0 OOQ μm) on the substrate.

The coercive force of the obtained magnetic disk was measured using a sample vibrating magnetometer, and the results are shown in Table 11.

*) Intermediate electrode position and shape a=/m, b=/xm, c=/za! rm, d=j'A
mx.

e=200111 Shape: Forming cylinder surrounding the entire outer periphery of the target /
[Effects of the Invention] The present invention is industrially useful because a magnetic recording medium having a high coercive force and suitable for high-density recording can be easily manufactured.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of the sputtering apparatus of the present invention, and FIG. 2 is a detailed diagram thereof. In the figure, l
is the target, ko is the substrate holder, 3 is the substrate, Hiro is the intermediate electrode, S is the power supply for sputtering, 6 is the power supply for the intermediate electrode, ri is the sputter erotic silane part of the target/Zahabe (magnet for Dagnetron, D is the DC Magnetron cathode, 1
0 indicates the main body of the film forming apparatus, and /l indicates the grounding part of the main body of the film forming apparatus. FIG. 3 is a part of a cross-sectional view showing an example of the position and shape of the intermediate electrode. Figures 1 to 73 (excluding Figure ii) are schematic diagrams and detailed diagrams showing other examples of sputtering equipment suitable for carrying out the present invention. FIG. ii is a schematic diagram showing a sputtering apparatus used in a comparative example of the present invention.

Claims (3)

[Claims] (1) In a method for manufacturing a magnetic recording medium in which a cobalt-based alloy magnetic thin film is formed on a substrate by sputtering,
An intermediate electrode having a shape that surrounds at least 1/2 of the outer circumference of the sputter erosion end of the target is provided near the target, and a positive potential is applied to the intermediate electrode with respect to the grounding part of the substrate and the main body of the film forming apparatus. A method for manufacturing a magnetic recording medium characterized by forming a cobalt-based alloy magnetic thin film (2) From a position 1/5 of the distance between the target surface and the substrate surface in the direction of the substrate with the target surface as the reference, 30 m in the opposite direction to the substrate with the target surface as the reference
2. The method of manufacturing a magnetic recording medium according to claim 1, wherein at least a portion of the intermediate electrode is provided between positions m apart. (3) Claim 1 or 2, wherein the intermediate electrode is provided between the outer periphery of the sputter erosion end of the target and a position 200 mm away from the outer periphery in the direction of the outer periphery of the target. A method for manufacturing a magnetic recording medium as described in .