JPH02244421A - Thin-film magnetic disk and production thereof - Google Patents

Abstract

PURPOSE:To obtain the magnetic medium which exhibits stable magnetic characteristics between production lots in the case of making mass production of magnetic disks by using a magnetic metallic layer formed by incorporating oxygen within a range from 0.01atomic% to 5atomic% into the magnetic metallic layer as the magnetic recording medium. CONSTITUTION:The magnetic disk which uses the magnetic metallic layer having cobalt (Co) as one of the elements to constitute the magnetic layer consisting of the thin metallic film of an alloy is formed by using the magnetic metallic layer which is incorporated with the oxygen (O) in the range from 0.01 atomic% to 5 atomic% to control the crystal grain size of the magnetic layer as the magnetic recording medium. Since the finer crystal grains are formed by introducing a proper ratio of H2O into a sputtering gaseous atmosphere, the magnetic disk constituted by coating a disk substrate with an intermediate layer and forming the magnetic layer thereon is first suppressed in the growth of the crystal grains in the intermediate layer, by which the finer grained film is obtd. The film having the small crystal grain size is obtd. as well for the magnetic layer to be formed thereon. The magnetic film which exhibits the stable magnetic characteristics at the time of production of the magnetic disk in particular is obtd. with respect to the magnetic medium to be used for the magnetic disk.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic medium used in a magnetic disk, and more particularly to a magnetic film that exhibits stable magnetic properties during the production of magnetic disks, and a method for manufacturing the same.

[Conventional technology]

Conventionally, alloy magnetic media based on cobalt (Co) are cobalt-nickel (Co-Ni), cobalt-nickel (Co-Ni), and cobalt-nickel (Co-Ni).
Chromium (Co-Cr), cobalt-platinum (Co-P
t), etc., and various combinations of compositions have been considered for each magnetic medium.

These are JP-A-60-111323, %KAI-62
-257617,'l? Kaisho 62-257618
, % Kaikai 63-160011, etc. In addition, as shown in the above-mentioned known examples,
Since CO alloys have low corrosion resistance, applications and announcements have been made for magnetic media in which a third element is mixed in order to improve the corrosion resistance. Specifically, Co-Ni-P
t, Co-Ni-Cr, Co-Pt-Cr, C
Examples include o-Ni-Zr.

In addition, since these CO alloy-based magnetic media have a hexagonal close-packed crystal structure (HCP) based on Co, an intermediate layer such as Cr, Mo, W, etc. is placed on the substrate surface between the substrate and the magnetic medium.
By forming the magnetic thin film after aib, the magnetization container axis of the magnetic medium, that is, the C axis of the hexagonal close-packed crystal structure, can have an in-plane component. It has been shown that this improves the magnetic properties in the in-plane direction.

Generally, sputtering equipment for forming these magnetic materials as a film on a disk substrate has a configuration called an in-line system, and is suitable for manufacturing disks in large quantities. In other words, it is a sputtering apparatus in which various vacuum chambers such as a loading (preparation) chamber for substrates, various film forming chambers for intermediate layers, magnetic layers, protective layers, etc., and an unloading (unloading) chamber are continuously connected, and each vacuum chamber has a gate. Separated by valves or slits. The structure is such that the intermediate layer, magnetic layer, retention layer, and film can be continuously formed while the disk substrate is held in a substrate carrier and transported through each vacuum chamber without being exposed to the atmosphere. Therefore, the substrates are continuously transported,
It is possible to manufacture a large amount of magnetic disks by forming a film or the like.

[Problem to be solved by the invention]

When producing magnetic disks using the mass production sputtering apparatus described above, heating and sputtering must be repeated over a long period of time while transporting a large number of disk substrates and substrate carriers.

The inventors conducted an investigation and found that the concentration of residual impurity gas relative to Ar gas gradually increases in the sputtering gas atmosphere due to this repeated process. Here, the residual impurity gas in the sputtering atmosphere is mainly hydrogen (
crow), carbon (C), water (H, O).

Nitrogen (common), -carbon oxide (CO), carbon disilonide (COt)
) and other hydrocarbons (CxHy). These gases can be measured with a quadrupole gas mass spectrometer.

This is because the gas adsorbed on the surface of the substrate or substrate carrier is released due to heating, or the gas adsorbed on the inner wall of the vacuum chamber is warmed and released and diffused into the sputtering gas atmosphere. be.

According to the research conducted by the present inventors, it has been found that when the magnetic film of the prior art described above is formed by sputtering during a long sputtering process, the reproducibility of magnetic properties deteriorates due to the influence of residual gas in the sputtering atmosphere. Ta. In particular, coercive force (Ha
) variations greatly affect electromagnetic conversion characteristics.

Especially in the sputtering gas atmosphere during mass production, the amount of water (H, O) gas increases significantly as the number of films deposited increases.
The concentration of ferrite relative to Ar gas could reach several percent, and the magnetic properties varied greatly depending on the concentration of water. In addition, the concentration of other residual impurity gases also increases with the increase in the number of films formed, but the concentration with respect to Ar gas is
, OS* or less, and no influence on magnetic properties was confirmed.

An object of the present invention is to provide a Co-based magnetic medium that exhibits stable magnetic properties in the production loft when mass-producing magnetic disks.

Means for Solving C1111g] In order to achieve the above object, it is necessary to keep the residual gas concentration constant at all times in the thin film forming process by sputtering. Here, the residual impurity gas with respect to Ar gas is 0, which accounts for most of the amount of residual impurity gas.

A method of keeping the concentration of water in the sputtering atmosphere constant is to mix Bo into the sputtering gas in advance at a concentration commensurate with the variation in HtO gas concentration during sputtering.

In addition, by introducing O1, O1 and O1 are increased in the sputtering gas atmosphere.

Several methods can be considered for mixing H and O into the sputtering gas, and two examples will be given below. 1st
In this method, H is added in advance to Ar gas, which is a sputtering gas.
A sputtering gas atmosphere with a target concentration of 0 is created by using a mixed gas cylinder containing a certain concentration of O, and introducing this water mixed gas and high-purity Ar gas into the sputtering chamber at an appropriate ratio. can be obtained. The second method is
Separately from Ar gas, HIO gas is introduced through a dedicated introduction route.
This is a method of introducing water vapor into the sputtering chamber using the vapor pressure of tO water.

Therefore, apart from a high-purity Ar gas cylinder, a mountain of liquid O
By using a cylinder containing a large amount of water vapor and adjusting the amount of water vapor introduced, it is possible to obtain a sputtering gas atmosphere with a desired concentration of phosphorus.

Also, the problem that occurs when &0 is introduced into Ar.

0! By pre-mixing 0 and O8 into the Ar gas in an amount comparable to 0 and 0, the same effect as when introducing )(to) can be obtained.

[Effect]

Generally, when forming a metal film by sputtering, residual impurity gas in the sputtering gas atmosphere is kept as low as possible.

The reason for this is that residual impurity gases may be occluded in the film during sputtering, or may react with chemicals during sputtering to form compounds.

However, the Co alloy magnetic medium shown in the above-mentioned known example has a trace amount of 0.000 to 0.0000% in the sputtering gas atmosphere. The amount of oxidation does not seem to be sufficient to significantly affect the magnetic properties. From this, it is considered that the reduction effect of the oxide is caused by the peak that increases in the same way as 0 when HtO is introduced.

Furthermore, it can be confirmed that crystal grains become finer by introducing an appropriate amount of HI3 into the sputtering gas atmosphere. In a magnetic disk in which a magnetic layer is formed by coating an intermediate layer on a disk substrate, growth of crystal grains in the intermediate layer is first suppressed, resulting in a fine film. A magnetic layer formed thereon also has a small crystal grain size.

However, if the concentration of HtO introduced is too high, oxidation will proceed too much or the film will become amorphous without crystal growth, resulting in deterioration of magnetic properties.

When the crystal grains of the magnetic film become finer, disk noise in electromagnetic conversion characteristics is reduced, and the reproduced signal/noise ratio (S/N ratio) of the recorded signal is improved.

〔Example〕

An embodiment of the present invention is shown below. The features of the present invention include:
O is contained in the magnetic layer, the intermediate layer, or both of these films. Methods for incorporating 0 into the film include introducing 0 into the sputtering gas atmosphere, and using argon gas mixed with 0 gas or argon gas in place of 0, and the like.

In this example, an intermediate layer is coated on the N1-P substrate,
A horizontal recording magnetic disk having a layer structure in which a magnetic layer is formed thereon, and a horizontal recording magnetic disk having a layer structure in which a magnetic layer is directly formed on the N1-P substrate surface will be described.

The target of the magnetic medium investigated in this example was, for example, a COo'1s-Cr film as a two-element magnetic material,
, e Coo, v-Nio-hot + COo, 1g-
Pt6 +I! As a three-element magnetic material, Co6.
@-Ni(,4-Cr,) 4. .

Co(14-Nlo, sa-Zro-0? #C
oo, @-Pt64-Cr(, -Os, etc.) were used.

Further, if necessary, a Cr film was formed as an intermediate layer on the surface of the N1-P magnetic disk substrate, and a magnetic medium was formed on this. Then, HtO is introduced into the Ar gas.

Crow, 0. We investigated the effect of the amount of incorporation on the magnetic properties of various magnetic films.

In order to clarify the comparison with the present invention, a magnetic disk having an intermediate layer and a magnetic layer containing no O was first produced.

The film forming apparatus used was an in-line sputtering apparatus as described above. FIG. 1 shows a schematic diagram of the sputtering apparatus. In this sputtering apparatus, a plurality of disk substrates 2 are simultaneously set on a carrier that is conveyed while holding disk substrates called - plate-shaped pallets 1, and the pallets are palletized while maintaining a vacuum in a vacuum chamber. Transport system 15
The substrate was heated and various layers were formed by sputtering while being transported.

Gas analysis in the sputter gas atmosphere was carried out by drawing a portion of the gas near the sputter discharge into the analysis tube using the differential pumping system 9. A quadrupole gas mass spectrometer was used as the gas analyzer 10 in the analysis tube.

The concentration of the residual impurity gas in the sputtering gas atmosphere was expressed as the ratio of the impurity gas detection peak to the Ar detection peak of the gas analyzer. For example, if the detected gas is expressed by mass number (molecular mass/ion valence = M/e), Ar is 4
0, H, O is 18. Therefore, when expressing the concentration of N20, it is expressed as (peak number 18/peak number 40) x 100 (h).

Although the gas concentration expressed by this measurement method does not represent the concentration ratio of the absolute amount of sputtering gas, there is no problem in expressing it as a relative concentration.

Various magnetic disks were manufactured using the sputtering system as described above.

(Example 1) First, in order to clarify the comparison with the present invention, a case will be described in which a magnetic disk was manufactured without introducing HtO into the sputtering gas (Ar).

In this apparatus, nine disk substrates 2 can be set on one pallet l, and this pallet l is sequentially sent from the carrying-in chamber 3 to the heating chamber 5 and film-forming chambers 6, 7.8, where films are formed. Ru. The conveyance speed at this time was 20 cmZ. This pallet is heated to 180° C. in a substrate heating chamber. And 3000 Cr for the middle layer! Co-Ni
-Zr was deposited at 400X.

At this time, only pure Ar was introduced as the sputtering gas, and the pressure of the sputtering gas atmosphere was set to 10 mTorr. Further, the concentration of residual impurity gas in the sputtering was monitored using a gas analyzer 10. Figure 2 shows the monitoring results. As shown in Figure 2, as the number of pallets to be deposited increases, the H
l gradually increased from 0.17% to 1.3 at the 20th pallet, and H3O gradually increased from 0.19% to 2.6 at the 20th pallet. .

When a disk is manufactured under such conditions, the magnetic properties of the manufactured magnetic disk, especially the coercive force (Ha)
) and investigated the disc noise of electromagnetic conversion characteristics.

(Example 2) Using the same sputtering system as in Example 1, N1-P was produced in a sputtering atmosphere in which Ar and H,0 were introduced as sputtering gases.
On the substrate, Cr was formed to a thickness of 30,001 as an intermediate layer, and Co--Ni--Zr was formed as a magnetic layer to a thickness of 400.times. For H, O, put pure water into a sample cylinder, and from there water vapor gas (H, 0 gas) is released into the vacuum chamber by the vapor pressure of the water.
was introduced. Then, while monitoring the gas analyzer, the HtO flow regulating valve was adjusted so that the sputtering gas atmosphere had the desired H and O concentrations.

In this example, samples were prepared in which the concentration of H,0 in the sputtering gas atmosphere was varied from 0.1% to 5%. The conditions for forming other layers are the same as in Example 1. However, when H3O is mixed into the sputtering gas atmosphere, the film formation rate changes slightly depending on the amount of H3O mixed in, and H! The higher the O concentration, the faster the film formation rate will be.

Therefore, taking this into consideration, the power applied to the target was adjusted so that the thickness of the deposited film would be constant.

(Example 3) Ar and O. N1-P in a sputtering atmosphere introducing
On the substrate, Cr was formed to a thickness of 30,001 as an intermediate layer, and Co--Ni--Zr was formed as a magnetic layer to a thickness of 400.times.

The gas introduction method is pure Ar gas and 0. Ar gas mixed with 2% is used, and the introduced gas is 0. The two gases were mixed so that the concentration reached the desired concentration. In this example,
Samples were prepared in which the 01 concentration in the introduced Ar gas was varied in the range of 0.01% to 1%. Then, the gas in the sputtering gas atmosphere was monitored using the gas analyzer 10. The conditions for forming the other six films are the same as in Example 1.

0 in sputtering gas atmosphere. The variation in film formation speed due to concentration is 0! As the concentration increases, the film formation rate decreases. Therefore, as in Example 2, adjustments were made to keep the film thickness constant.

(Example 4) Using the same sputtering system as in Example 1, Ar, H8, and 0.5% sputtering gas were used as sputtering gases. N1 in a sputtering atmosphere introducing
On the -P substrate, Cr was formed to a thickness of 30,001 mm as an intermediate layer, and Co--Ni--Zr was formed as a magnetic layer to a thickness of 400 mm. The gas introduction method is pure Ar gas and H2
Ar gas mixed with 2*(H,:O,=2:1) and O3 was used, and the two gases were mixed so that the Ml-01 concentration of the introduced gas became the desired concentration. In this example, the amount of Ol in the introduced Ar gas is from 0.011 to 1.
Samples were prepared in which the temperature was varied within a range of 91. Then, the sputtering gas atmosphere was monitored using the gas analyzer 10.

The conditions for forming the other six films were the same as in Example 1.

(Example 5) Using the same sputtering system as in Example 1, a part of the gas introduction part was changed, and A was used as the sputtering gas in the Okinoki layer sputtering chamber.
r and H20 were introduced, and only Ar was introduced as a sputtering gas into the magnetic layer sputtering chamber. Therefore, in the intermediate layer sputtering chamber, N1
- Form an intermediate layer on the P substrate, and in the magnetic layer sputtering chamber,
A magnetic layer was formed in an Ar sputtering gas atmosphere without introducing H30. In this example, Cr is used as the intermediate layer.
A film thickness of 30,001× was formed in an H10 atmosphere, and a Co-Ni-Zr film was formed as a magnetic layer in a film thickness of 400× in an Ar atmosphere. The conditions for forming the other six films are the same as in Example 1.

(Example 6) Using the same sputtering system as in Example 1, Ar and H30 were introduced as sputtering gases, and only the magnetic layer was directly formed on the Ni-P substrate. In this example, an intermediate layer was not formed between the substrate and the magnetic layer, and the magnetic layer was formed of Co-P t -Cr with a thickness of 4001 mm. The sputtering gas introduction method at this time is the same as in Example 2. In this practical example, samples were prepared in which the concentration of H,0 in the sputtering gas atmosphere was varied from 0.1% to 5%. The conditions for forming the other six films are the same as in Example 1.

(Comparative Example of Examples 1 to 6) Various characteristics of the magnetic disks obtained from Examples 1 to *Remaining Feed 6 were compared below.

First, the content of 0 contained in the intermediate layer and magnetic layer formed on the disk substrate was measured using Auger electron spectroscopy (AES).
The zero concentration in the membrane was analyzed using the analytical method of Table 1 shows the results.

The O concentration in Example 1 is 0.1% or less, but by introducing Lo, o & into the sputtering gas atmosphere, the Cr intermediate layer,
The presence of more O in the CO magnetic layer than in Example 1 is confirmed. Furthermore, in the sample of Example 5, the Cr film contained approximately 0.8% O, but the presence of 0 could not be confirmed in the CO magnetic film.

Next, Table 2 compares the variations in magnetic properties of the magnetic disks obtained by each manufacturing method, particularly the variations in coercive force (Hc). Here, I(,0,
or 0. The concentration of Example 2: 1'A (Ht
O), Actual tlA Example 3: 0.11 (Ox) Example 4: 0.2 (Ot), 0.4 (H3) Example 5: Results of a sample in which a film was formed with 1 (HtO) It is.

Furthermore, Table 2 shows the values of the coercive force (He) and the crystal grain size of the magnetic medium of the samples in which the H20 concentration was changed in Example 2.

Table 2 Table 3 As shown in FIG. 2, in the conventional film forming method, the amount of H, O, O, , H gases increases depending on the number of pallets transported. Also! ! 3, when the H snow concentration in the sputtering gas atmosphere changes, it depends on this.Example 1
has a large variation in coercive force. However, as shown in Table 3, the variation in coercive force is reduced by the manufacturing method in which an appropriate amount of zero is actively included in the magnetic layer or intermediate layer.

On the other hand, Table 3 shows that as the H2O concentration increases, the crystal grain size of the magnetic medium becomes finer. Generally, there is a correlation between the particle size of a magnetic material and its coercive force, and the coercive force exhibits a maximum value at a certain particle size. This fact is also written in the Magnetic Material Hasid Book (published by Asakura Shoten).

Therefore, it is considered that the change in HtO concentration in the sputtering gas causes the crystal grain size of the magnetic medium to change, and the coercive force to change accordingly. From this fact, the crystal grain size of the magnetic layer can be controlled by the amount of H, 0, or 02 introduced, and this also makes it possible to control the coercive force. Here, the crystal grain size is measured using a scanning electron microscope (SEM).
Observation was made using Electron Microscopy.

Table 4 shows examples in which the magnetic properties, crystal grain size of the magnetic layer, and disk noise of magnetic disks obtained by various manufacturing methods were compared. Here, we will focus on the magnetic properties, especially the coercive force (H
a) and S are shown. Here, S* is a value representing the squareness ratio of coercive force.

As shown in Table 4, in both Example 1, which is a conventional manufacturing method, and Example 1, which is the present invention, the variation in coercive force is small. Furthermore, when the amount of H,0 or false introduced increases, the coercive force decreases, and the limit of the amount introduced is determined here. As mentioned earlier, this means that H,0
, 0, can control the coercive force by the amount of introduced.

Further, in all the examples according to the present invention except Example 5, it was confirmed that S was improved.

Furthermore, it can be seen that in Examples 2 to 6 of the present invention, the crystal grain size of the magnetic film is smaller than in Example 1, which is a conventional manufacturing method. This is because the higher the HtO or O3 concentration, the finer the particle size tends to be.

This reduces disk noise, which may be reduced to about 1/3 of the conventional manufacturing method.

As described above, as shown in Example 6 in Table 4, Co--Pt--Cr without an intermediate layer was also effective.

In this example, Co-Ni-Zr + Co-Pt-Cr
However, similar effects were observed with other Co-based alloy magnetic materials. For example, C with one element added to Co
G-Cr, Co-Ni, Co-pt, etc.
Co-N1 (:r + Co-C
r-Hf etc.

In addition, in this embodiment, only the intermediate layer and the magnetic layer have been described, but other elements constituting the magnetic disk, such as coating with a protective layer and forming the N1-P substrate, are well-known. That's right.

〔Effect of the invention〕

By introducing appropriate amounts of either water (HIO), oxygen (O1), or hydrogen (H2O) and oxygen (O,) into the sputtering gas of the present invention, the following favorable properties can be obtained. It was done.

Since the relative concentration of the residual impurity gas in the sputtering gas atmosphere to Ar is almost constant, the magnetic properties, especially the coercive force (Hc) value (±400e), are stable, and manufacturing with good reproducibility is possible.

Crystal grains become finer (40 nm) Disc noise improves magnetic properties, especially squareness ratio and r. This leads to improved disk performance.

[Brief Description of the Drawings] Fig. 1 is a diagram schematically showing an in-line sputtering apparatus used in an embodiment of the present invention, and Fig. 2 is a diagram showing the fluctuation of residual impurity gas in the sputtering atmosphere in the prior art. FIG. 1...Pallet 2...Disk board 3
... Loading chamber 4... Carrying out chamber 5... Heating chamber 6... Film forming chamber (intermediate layer) 7... Film forming chamber (magnetic layer) 8... Film forming chamber (protective layer) 9... Differential pumping system 10... Gas analyzer 11... Flow rate adjustment valve 12... Gas flow rate controller 13... Gate valve 14... Vacuum pumping system 1
5...Pallet transport system

Claims (1)

[Claims] 1. In a magnetic disk using a metal magnetic layer containing cobalt (Co) as one of the elements constituting the metal thin film magnetic layer of an alloy as a magnetic recording medium, the metal magnetic Oxygen (O
) is used as a magnetic recording medium. 2. In a magnetic disk in which an intermediate layer made of a non-magnetic metal is provided between a magnetic disk substrate and a metal thin film magnetic layer made of an alloy containing cobalt (Co) as a component, zero in the non-magnetic intermediate layer is provided. Oxygen (O
) A magnetic disk characterized by having a nonmagnetic intermediate layer containing. 3. A magnetic disk characterized in that the substrate surface of a magnetic disk substrate is coated with the intermediate layer according to claim 2, and further the magnetic layer according to claim 1 is formed thereon. 4. A method for forming a thin film by sputtering of the nonmagnetic intermediate layer according to claim 2 or the magnetic layer according to claim 1, or claim 3
In the method for forming a sputter thin film on a magnetic disk described above, the gas component in the sputtering atmosphere is characterized in that water (H_2O) gas is introduced into argon (Ar) gas used as a sputtering gas to form a sputter thin film. A method for manufacturing magnetic disks. 5. In the method for forming a thin film by sputtering of the non-magnetic intermediate layer according to claim 2 or the magnetic layer according to claim 1, or the method for forming a thin film by sputtering of a magnetic disk according to claim 3, a vacuum chamber is used as the sputtering gas. A thin film is formed by sputtering in a sputtering gas atmosphere containing 0.01% to 5% of oxygen (O_2) and 0% to 5% of hydrogen (H_2) in argon (Ar) gas introduced into the process. A method for manufacturing magnetic disks. 6. In a magnetic disk using a metal magnetic layer containing cobalt (Co) as one of the elements constituting the alloy thin metal magnetic layer as a magnetic recording medium, 0.01% of the metal magnetic layer is used as a magnetic recording medium. Oxygen (O
1. A magnetic disk characterized in that a metal magnetic layer is used as a magnetic recording medium, the crystal grain size of the magnetic layer being controlled by controlling the crystal grain size of the magnetic layer.