JPH0635654B2 - Target material with high stability of thin-film magnetic properties against atmospheric changes - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a highly stable target material for a Fe—Ni-based soft magnetic thin film used for thin film heads, etc., which has a stable atmosphere and is used for forming a sputtered thin film. The present invention relates to a target material having extremely high stability, no variation in the soft magnetic characteristics of the sputtered thin film after formation, and extremely high stability against fluctuations in the sputtering atmosphere that exhibit excellent soft magnetic characteristics.

BACKGROUND ART Fe-Ni-based soft magnetic thin films, for example, soft magnetic thin films made of permalloy whose main component is about 80% Ni-Fe, are used as a backing layer of a perpendicular magnetic recording medium, a core or a yoke of a thin film head for magnetic recording, and the like. Is used, including Mo permalloy or Mo and
Mo-Cu permalloy containing Cu is widely used.

As a method for forming this thin film, a sputtering method is often used. In this sputtering method, a voltage is applied between the anode of the base material and the cathode of the target material of the same material as the permalloy thin film of the required composition, and the target surface atoms are knocked out by the cations and deposited on the base material and the required surface to make the permalloy. This is a method of forming a thin film.

Permalloy thin films of any composition are extremely sensitive to the sputtering atmosphere conditions during thin film formation, and in order to obtain a thin film with excellent soft magnetic properties, it is necessary to strictly control the sputtering atmosphere conditions during thin film formation, and the ultimate vacuum The degree is 2 × 10 ^-6
It is necessary to maintain a high degree of vacuum of Torr or less, preferably 1 × 10 ^-6 Torr or less.

To maintain a high degree of vacuum, the inner wall of the vacuum chamber is heated to release the gas and moisture adhering to the inner wall, or it is called pre-sputtering. Before forming a thin film on the target substrate, the shutter etc. It was necessary to carry out the operation of depositing the thin film on the other target for a long time.

However, even if the atmosphere is controlled extremely strictly as described above, the magnetic properties of the permalloy thin film are significantly deteriorated even if it is affected by the outside air humidity during the work, or even a slight leak occurs, and the working conditions There is a problem in that variations in characteristics occur every time.

Also, when continuously forming permalloy thin film on a long film etc., the obtained magnetic properties have a large time dependency, and even if the thin film is formed continuously for a long time, it will converge to a certain characteristic value. There was a problem that it was difficult to do.

On the other hand, the target material for obtaining the permalloy thin film has been improved so far mainly for improving the sputtering efficiency to improve the cooling efficiency or the material utilization efficiency. No target material has been proposed considering the stability against fluctuations.

In addition, Japanese Patent Publication No. 47-290690 discloses a Ni-
Although magnetic alloys for magnetic recording and reproducing heads with high magnetic permeability and high hardness in which Nb is added to Fe alloys have been proposed, the above-mentioned known thin films and target materials, including the above magnetic alloys, are different from those in the sputtering atmosphere. The reduction and stabilization of the magnetic properties of the formed sputtered thin film are not taken into consideration, and neither of the above problems can be solved, and the soft magnetic properties of the obtained thin film can be stably obtained. Required extremely strict atmosphere control during thin film formation.

OBJECT OF THE INVENTION The present invention has an object of a sputtering target material capable of obtaining a soft magnetic thin film having excellent characteristics even under atmospheric conditions in which only a pretreatment operation such as a relatively low ultimate vacuum or a short time presputtering is performed, In particular, even with a slight variation in the atmospheric conditions, the drawbacks of the conventional target material that causes large deterioration and large variation in magnetic properties are solved, and a thin film that exhibits excellent soft magnetic properties is stably stabilized. The purpose is to obtain a target material for a highly stable, soft magnetic thin film that fluctuates against atmosphere.

Structure and Effect of the Invention The present invention has variously studied for the purpose of a target material for a soft magnetic thin film in which excellent soft magnetic characteristics are stably obtained.
By including a specific amount of one or more of V, Nb, Ta, Ti, Si, and Al in a so-called permalloy component composition containing Fe and Fe as a main component, a change in the sputtering atmosphere condition or a comparative condition The present invention has been completed by finding that a soft magnetic thin film having extremely high stability and excellent soft magnetic properties can be obtained without being affected by the above.

That is, the present invention is mainly composed of 40 atomic% to 90 atomic% of Ni and 10 atomic% to 50 atomic% of Fe, and 0.5 atomic% to 15 atomic% of at least one of V, Nb, Ta, Ti, Si and Al. The gist of the target material is that it has a high stability of the thin film magnetic characteristics against the fluctuation of the sputtering atmosphere.

In addition, this invention is Ni 40 atom% ~ 90 atom%, Fe 10 atom%
~ 50 at.% Of main component and at least one of Mo, W, Co, Cu as an accessory component at 15 at.% Or less, further containing V, Nb, T
It is a target material having high stability of thin film magnetic characteristics against changes in sputtering atmosphere, characterized by containing at least one of a, Ti, Si and Al in an amount of 0.5 atom% to 15 atom%.

The target material for a soft magnetic thin film according to the present invention is characterized by its unique composition and has the following effects if it has a specific composition. That is, as is apparent from the examples, the obtained thin film has excellent magnetic properties as compared with conventional permalloy and Mo permalloy, and is insensitive to the atmospheric conditions during sputtering, and has a lower vacuum degree and Even with a short pre-sputtering time, the resulting soft magnetic thin film has little deterioration in magnetic properties such as coercive force and magnetic permeability, and has extremely high stability in the atmosphere during sputtering. Is the same after obtaining the heat treatment after the thin film formation. Needless to say, when the atmosphere is controlled extremely strictly during sputtering, superior magnetic characteristics can be stably obtained.

Therefore, in the industrial mass production scale, it becomes easy to control the atmosphere during sputtering, and even if the atmospheric conditions change within a lot or between lots during continuous operation for a long time or when films are continuously sputtered, for example, variations in magnetic properties can occur. A thin film having a small amount can be obtained at a low cost.

In the present invention, the target material used is one previously alloyed with the required composition, but if alloying is difficult or if rolling is difficult and the desired shape cannot be formed, a binary system or subcomponents are contained. A composite target material such as an embodiment in which a metal or alloy chip of the additional element is mounted or embedded on the permalloy alloy target may be used.

Further, the soft magnetic thin film obtained by the obtained target material according to the present invention can be improved in magnetic properties by heat treatment as in a normal permalloy thin film.
In the case of holding or gradually cooling at a temperature of 0 ° C. or lower, it is desirable that a transition element capable of suppressing the formation of Ni ₃ Fe ordered lattice is contained.

Reasons for limiting the invention The target material for a soft magnetic thin film of the present invention contains Ni and Fe as main components, and contains at least one of V, Nb, Ta, Ti, Si, and Al.
It is characterized by containing 5 atomic% to 15 atomic%, which makes it easy to control the atmosphere during sputtering on an industrial mass production scale and obtain a thin film with little variation in magnetic characteristics even when the atmospheric conditions change. Have the effect of being There are many unclear points about the mechanism by which this effect is obtained, but it can be considered as follows.

It is generally known that oxygen contained in the atmosphere during sputtering or oxygen decomposed from water enters the film and deteriorates the magnetic characteristics of permalloy. It is not clarified in what form this oxygen exists in the film, but in the thin film of the present invention, the presence of the above-mentioned additional elements having a higher affinity for oxygen than Ni and Fe causes It is considered that the contained oxygen expresses the original magnetic properties of the permalloy thin film without directly affecting Ni and Fe.

However, binary permalloy or Mo, W, Co,
Compared with Ni and Fe such as Cu, the conventional target materials that have no difference in affinity with oxygen at high temperature or, conversely, contain only elements with low affinity are liable to be affected by oxygen as described above. It is considered that even a slight deterioration causes a sensitive reaction and deterioration of magnetic characteristics occurs.

Therefore, in the present invention, in order to obtain the effects of the above elements, it is necessary to contain at least one kind of V, Nb, Ta, Ti, Si, and Al in an amount of 0.5 atomic% or more, preferably 2 atomic%.
As described above, it is more preferable that the content is 4 atomic% or more. However, if the content of the above elements exceeds 15 atom%, the saturation magnetic flux density is significantly reduced, which is not preferable.
The following content is desirable, preferably 12 atom% or less, and more desirably 10 atom% or less. Further, the content may be appropriately selected in consideration of the saturation magnetic flux density and the stability of desired magnetic characteristics in a thin film forming atmosphere.

The additional elements are Ni and Fe, which are the basic components of permalloy.
Is effective in a thin film in the range of 40 atomic% to 90 atomic% of Ni and 10 atomic% to 50 atomic% of Fe.
The same effect is exhibited as described above even in a thin film containing any of W, Co and Cu.

The magnetic property of the soft magnetic thin film obtained from the target material according to the present invention is a coercive force of 100 _e or less.

Examples Example 1 The following three types of targets were prepared for thin film formation. The composition is shown in wt% below.

(1) 79.7Ni-5Mo-Fe (diameter 100mm, thickness 3.5mm) (2) As shown in Fig. 1, Si chip (11) is formed on the same 79.7Ni-5Mo-Fe target material (10) as (1). (Thickness 0.6mm × 5mm × 5m
(3) 79.9Ni-4.9Nb-2.1Si-Fe (diameter 100mm, thickness 3.5mm) The above target material (1) is for comparison of conventional compositions. 2)
The target material of (3) is according to the present invention.

An RF magnetron sputtering device is used as the sputtering device, and the substrate has a coefficient of thermal expansion near room temperature of 98 × 10 ⁻⁷ /
The substrate holder was water-cooled using glass having a size of 0.9 mm and a thickness of 0.9 mm × 25 mm × 25 mm, and the maximum temperature of the substrate was maintained at 50 ° C. to 55 ° C. in any sputtering.

The sputtering conditions are high vacuum (A) and low vacuum (B).
As shown in Table 1, the coercive force of the easy magnetization axis of various thin films obtained was examined by using a BH tracer.
The results in the table were obtained.

In Table 2, a, c, and e are high vacuum degrees (A), b, d, and f are low vacuum degrees (B), and a, b
Is a comparative example thin film with the target material of (1), and c and d are (2)
The thin film of the present invention, e, f by the composite target material of
This is the case of the thin film of the present invention using the target material of (3).

In Table 2, in the composition formulas shown in two steps a to f, the upper part is the target material and the lower part is the thin film composition. The thin film composition was ± 0.5 when examined with an X-ray microanalyzer.
Since an error of about 10% is expected, it is judged that there is no large difference in component composition between thin films formed of the same target material.

The thin film of the comparative example has a significant difference in magnetic characteristics between the high vacuum forming condition a and the low vacuum condition b. The coercive force was about 0.90 _e at a, but was 120 _{8 at} b. The coercive force increases more than 13 times, and it can be seen that a slight deterioration of the atmosphere during thin film formation causes a remarkable deterioration in magnetic characteristics.

On the other hand, in the case of the thin film according to the present invention, the thin film forming condition is between the high vacuum and the low vacuum, which is much smaller than that in the comparative example. That is, in comparing c and d, c
The coercive force of 0.80 _e is only 2.5 times larger than 20 _e of d, and there is almost no difference in coercive force between e and f regardless of the deterioration of the thin film forming atmosphere. It was 0.30 ₈ .

As is clear from Table 2, the permalloy thin film target material of the present invention containing Si or Nb and Si is less sensitive to the atmospheric conditions during sputtering, as compared with the conventional Mo permalloy thin film target material. Even if the degree of vacuum is lower and the sputtering time is shorter, the magnetic properties such as coercive force and magnetic permeability of the obtained soft magnetic thin film are less deteriorated, and it has extremely high stability in the atmosphere during sputtering. I understand.

Example 2 Six alloy target materials of 79Ni-4.5Nb-Fe, 79Ni-7Nb-Fe, 79.7Ni-5Mo-Fe82Ni-2Al-Fe, 79.7Ni-5Mo-3Si-Fe and 79Ni-4Ti-Fe were used. Then, using the same sputtering apparatus as in Example 1, sputtering was performed under the same conditions as in Table 1, and 10 kinds of thin films according to the present invention and conventional
A Mo permalloy thin film was prepared.

The component composition of some of the thin films obtained was measured with an X-ray microanalyzer, the coercive force of the easy magnetization axis was measured using a BH tracer without heat treatment, and the permeability of the difficult magnetization axis was measured. Measurements were made using an 8-shaped coil, and Table 3 shows the ultimate vacuum and the sputtering conditions such as the pre-sputtering time. The magnetic permeability is shown as the maximum value. The composition of the obtained sputtered thin film varied depending on the manufacturing conditions and the like, but Ni was within ± 1% of the target composition, and other compositions were within ± 30%.

As is clear from Table 3, the thin film made of the target material of the present invention containing about 6% Nb has an ultimate vacuum of 5 × 10 ^−6.
Even if it is manufactured in an atmosphere with a bad Torr level, there is almost no deterioration in coercive force and magnetic permeability as compared with the case of a vacuum of 1 × 10 ^-6 Torr.

In addition, a thin film made of the target material of the present invention containing about 8% Nb was produced even in a bad atmosphere with an ultimate vacuum of about 5.3 × 10 ⁻⁶ Torr and a pre-sputtering time of half, that is, 25 minutes. It can be seen that it has better magnetic properties than the examples. In addition, in the case of the above-mentioned Nb homologous elements V and Ta,
It was confirmed that the same effect as Nb was obtained, and Ti, Al, Si
It can be seen that also in the case of, the same effect as Nb can be obtained.

Therefore, the thin film made of the target material of the present invention has excellent magnetic characteristics as compared with the thin film made of the conventional target material, and the excellent characteristics described above can be stably obtained even when the atmosphere conditions for forming the thin film vary widely. It is clear that

Example 3 Using the thin films of a, b, c and d shown in Table 2 obtained in Example 1, heating was performed at 500 ° C. for 1 hour in a vacuum of 1 × 10 ⁻⁴ Torr, After that, heat treatment for slow cooling was performed, and the magnetic permeability (10 MHz) of the hard magnetization axis was measured using an 8-shaped coil. Table 4 shows the measurement results (highest value).

In the case of the Mo permalloy thin film of the comparative example, the magnetic permeability of the thin film b manufactured under a low vacuum and bad atmosphere conditions is only 1/6 of the magnetic permeability of the thin film a manufactured under a high degree of vacuum.

However, in the thin film obtained from the Si-containing target material according to the present invention, the thin film d under bad atmospheric conditions is
The magnetic permeability of the thin film c is about 1/2 of that of the thin film c produced under a high vacuum atmosphere, and it is clear that the characteristics after the heat treatment are not easily affected by the atmospheric conditions during sputtering.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a composite target material in Example 1. 10 …… 79.7Ni-5Mo-Fe target material, 11 …… Si chip.

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Claims (2)

[Claims] 1. Ni to 40 at% to 90 at% and Fe to 10 at% to 50 at% as main components, and at least one of V, Nb, Ta, Ti, Si, and Al at 0.5 to 15 at%. A target material having high stability of thin film magnetic characteristics against changes in sputtering atmosphere, which is characterized by containing. 2. A main component containing 40 atomic% to 90 atomic% of Ni and 10 atomic% to 50 atomic% of Fe, and 15 atomic% or less of at least one of Mo, W, Co and Cu as a subcomponent, and further containing V , Nb, Ta, Ti, S
A target material having high stability of thin-film magnetic characteristics against changes in sputtering atmosphere, characterized by containing at least one of i and Al in an amount of 0.5 atomic% to 15 atomic%.