JPS6057211B2 - Manufacturing method of magnetic recording media - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a high-density magnetic recording medium used in a magnetic disk device or the like.

High-density recording is an important issue in magnetic recording devices, and high-density recording requires reducing the thickness of the recording medium and increasing the coercive force Hc.

In magnetic disks, γF is applied on the disk to form the medium.
e. O. A widely used method is to make a magnetic film by coating a mixture of fine particles and a binder. However, since this method requires a binder, there is a limit to how thin the film can be made;
It is difficult to reduce the thickness to 0.7 μm or less. Other methods for forming the medium include reactive sputtering, reactive vapor deposition, and CD (chemistry).
calDeposition) method, CVD (Che-m
These methods allow the formation of even thinner continuous medium thin films. For example, the former sputtering method and vapor deposition method can yield a thin film of about 0.05 μm, and practically 0.15 μm. It will be done. However, when such a magnetic recording medium thin film is manufactured by the conventional J method, there are various difficulties in the manufacturing process and the magnetic properties of the resulting medium. For example, in the above-mentioned reactive sputtering method, iron (Fe) is sputtered onto a substrate in an argon gas atmosphere containing oxygen at about 10-° Torr.
A Fe2O3 nonmagnetic film is deposited, and this film is reduced to form Fe3.
Although an O4 (magnetite) magnetic film is produced, there are disadvantages in that the temperature margin of this reduction process is narrow, the reduction temperature is high, and the coercive force and squareness ratio are also relatively small. The present invention is an attempt to improve this point.
Cu) and cobalt (CO), and manganese (Mn
), nickel (Ni), aluminum (Ae), zinc (
Using an iron alloy containing one or more of Zn), zirconium (Zr), tin (Sn), and tantalum (Ta), α-Fe2O3 with a film thickness of 1 μm or less is formed by reactive sputtering or the like.
It is characterized by forming a film.

The α-Fe2O3 film thus obtained is reduced to form Fe3O
By using four films, a magnetic film with high coercive force can be obtained, and since the required temperature for the reduction process is low and the allowable temperature range is wide, it does not adversely affect the substrate, the reduction process is easy, and a high yield can be obtained. Furthermore, when this Fe3O4 high coercive force film is heat-treated in air, it oxidizes and becomes a γ-Fe2O3 film, which has good adhesion to the substrate and a squareness ratio of about O2, compared to about O2 in the conventional method. It becomes high. Next, this will be explained in detail with reference to examples. Figure 1 shows α-Fe2
The relationship between temperature and electrical resistance in the reduction process from O3 to Fe3O4 is shown. Curve C1 shows the case where an α-Fe2O film is formed on an aluminum substrate by reaction sputtering in 02-N mixed gas using additive-free Fe as a target, and this is reduced in hydrogen gas containing water vapor, and curve C2 is 3% (
(wt%, same hereinafter) F containing Mnl2%Cu, 2%CO
This is the reduction temperature vs. electrical resistance characteristic of Yanghe, which was subjected to reactive sputtering using e-alloy as a target under the same conditions and the resulting α-Fe2O3 film was reduced. 1σ~104 between dotted lines
The range of Ω-Cm is the Fe3O4 region, and 101Ω-
Cm or more range (α-Fe2O3 region, 1σΩ-C
The range after m is the Fe region. These curves Cl, .
As is clear from C2, when additive-free Fe is used, the reduction temperature margin is extremely narrow at 280 to 325°C; at temperatures below this, nonmagnetic and insulating α-Fe2O3 remains).
At temperatures higher than this, it becomes mere Fe metal. The allowable variation range of heat treatment temperature of about 50° C. is actually quite strict and requires precise temperature control. On the other hand, in the case of using the Fe-Mn-Cu-CO alloy of curve C2, the reduction temperature margin is expanded to 200 to 375°C, and temperature control is easy. Also, as is clear from this graph, the reduction temperature is low when using the above iron alloy, that is, about 300°C when using Fe without additives.
A temperature of about 200° C. is sufficient, which is a great advantage.

That is, if the heat treatment temperature exceeds 300°C, the disk of a large-area aluminum substrate will warp, making it impossible for the magnetic head to keep track of the medium at a constant distance, so the reduction treatment temperature should be below 300°C. It is desirable that it be good. In this respect, it is extremely preferable that the temperature for the above-mentioned iron alloys is around 200°C, which makes it possible to use aluminum for the media substrate, and together with the feature of a wide reduction temperature margin, this makes it possible to achieve certain good properties. magnetic thin film can be reliably deposited. In this example, an iron alloy target containing 3% Mnl, 2% CUl, 2% CO was used, reactive sputtering was performed in a 50% 02-50% N mixed gas, and α-Fe2O3 was deposited on an alumite-treated aluminum substrate.・A thin film was formed.

Thereafter, 250'C1 reduction was carried out for about 1 hour in a hydrogen gas atmosphere containing moisture to obtain a Fe3O4 film with high coercive force.
This Fe3α film was heat-treated in air at 300°C, and the coercive force was 7.
A γ-Fe2O3 film having a squareness ratio of 0.000e and a squareness ratio of 0.8 and good magnetic properties with good adhesion to the substrate was obtained. Among the additives, cobalt (CO) is useful for improving coercive force.

CO when using 3%Mn-2%Cu-X%CO iron alloy
The relationship between the amount added and the coercive force Hc is shown in the curve C1 in FIG.

As shown in this figure, when CO is zero or no addition is made, Fe
The Hc of the 3O4 film is about 3500e, while the CO
When 10% of is added, Hc becomes nearly 19000e,
During this period, Hc increases almost linearly with S. N instead of Mn
i. sAeNZn. ．． Zr. ．． Sn. ．． Similar results can be obtained by adding Ta.

Curve C3 in Figure 1 is for Fe alloy containing 3% Zn, 2% Cu, 2% CO, and curve C2 in Figure 3 is for Fe alloy containing 3% N1, 2% CUL.
Curve C3 in the same figure shows Fe alloy containing 2% CO and 3% Sn.
Curve C3 in Figure 5 is for an Fe alloy containing 3% Ta, 2% CUl2% CO, and curve C2 in the same figure is for an Fe alloy containing 3% Zrl2% CUl2% CO. , and the curve C2 in Figure 7 is 3% Afl2
The α-Fe
The reduction temperature-electrical resistance characteristics when 2O3 is reduced are shown. In addition, curve C2 in Figure 2 shows CO2 in 3%Znl2%Cu.
It shows the change in coercive force Hc with respect to the amount of CO added in the range of 0 to 10%. Similarly, curve C1 in FIG. 3%Snl2%Cu, and curve C1 in FIG. 6 is at 3%Zrl2%Cu, curve C2 in the same figure is at 3%Tal2%Cu, and curve C1 in FIG.
is Hc relative to the amount of CO added at 3% Af and 2% Cu.
shows the change in

In place of Nln, the above Ni. Even when using an iron alloy target added with Ae......, Fe3O4 film or even γ-Fe2O is formed in the same way as when using Mn.
3 membranes can be made.

In each case, Cu. ．． CO was 2% in both cases, Ni. A
', Zn. ．． Zr. ．． Sn. ．． A γ-Fe2O3 film was obtained under the same conditions as in the example for Mn, with Ta being 3% in each case, and the Hc of the film was Zrlzn. ．． Ae. ．． In the case of Ni, it is 7000e. ．． In the case of Ta, the value was 7500es, and in the case of Sn, it was 6500e, and the squareness ratio was 0.8 in both cases. Among the additives, Cu! 1Mn. Together with Ni... etc., it contributes to the improvement of reducibility.

In this respect, CO is exclusively useful for improving Hc, and this
%, the target Hc of about 7000e can be obtained. Additives, especially non-magnetic additives, impair magnetism if added in large amounts, so it is not preferable to use too large amounts. Therefore, CUl and COl and Ni. ．． MnlZnlAe. ．． Zr.
．． Sn. ．． Ta is in the range of 0.1 to 10%, preferably CUNCO is 2% as in the previous example, Ni. ．． Mn...
... is preferably mixed with Fe in a range of 3%. Ni,. Mn, etc. may be used alone or in combination of two or more. N1, Mn. ．． Zn is 1 to 5
% and A', ZnlSn. If Ta is mixed in a range of 1 to 4%, the squareness ratio Br/Bs will be 0.7 or more.
If it exceeds 10%, Ae2O3, ZrO2, SnO2, T
Precipitates of a2O5 are formed in the ferrite, deteriorating the magnetic properties.

Figures 9 and 10 show additive Ae. zrlSn. Ta
and Mn. Ni. ．． FIGS. 11 and 12 show the change in remanence Br with respect to the amount of Zn, and FIGS. ．．
Zr. ．． Sn. ．． Squareness ratio (Br/Bs
).

As explained in detail above, according to the present invention, an extremely thin magnetic thin film with good coercive force and squareness ratio can be easily produced with good yield, and a medium excellent as a high-density recording medium can be produced at a low cost. can be provided.

Brief explanation of the drawings Figures 1, 3, 5, and 7 are graphs showing changes in electrical resistance with respect to reduction temperature, Figures 2, 4, 6,
Figure 8 is a graph showing the change in coercive force due to CO addition.
All of them show the effects of the present invention.

Claims (1)

[Claims] 1. An iron alloy containing copper, cobalt, and one or more of manganese, nickel, aluminum, zinc, zirconium, tin, and tantalum is used to coat a substrate with a film thickness of 1 μm or less.
-Create a thin film of Fe_2O_3 and reduce the thin film to make Fe_2O_3
A method for manufacturing a magnetic recording medium, characterized by forming a magnetic film of _3O_4. 2. Claim 1, characterized in that a thin film of α-Fe_2O_3 is formed on a substrate by reactive sputtering of an iron alloy in an oxygen-argon gas atmosphere.
2. Method for manufacturing the magnetic recording medium described in Section 1. 3. α film thickness of 1 μm or less is applied to the substrate using an iron alloy containing copper, cobalt, and one or more of manganese, nickel, aluminum, zinc, zirconium, tin, and tantalum.
-Create a thin film of Fe_2O_3 and reduce the thin film to make Fe_2O_3
A method for manufacturing a magnetic recording medium, which comprises forming a Fe_3O_4 magnetic film and then further oxidizing the Fe_3O_4 magnetic film to form γ-Fe_2O_3. 4. Claim 3, characterized in that a thin film of α-Fe_2O_3 is deposited on a substrate by reactive sputtering of an iron alloy in an oxygen-argon gas atmosphere.
2. Method for manufacturing the magnetic recording medium described in Section 1.