JPS6240363A - Target member having excellent stability of thin magnetic characteristic against change of atmosphere - Google Patents

Abstract

PURPOSE:To obtain a material for a target forming a thin film whose magnetic characteristics are independent of a change of a sputtering atmosphere by adding the specified amount of Mn, Cr, V, Nb or the like to the composition of 'Permalloy(R)' consisting essentially of specified percentages of Ni and Fe. CONSTITUTION:0.5-15atom% one or more among Mn, Cr, V, Nb, Ta, Ti, Zr, Hf, Si, Al and Ge are added to the composition of 'Permalloy(R)' consisting essentially of 40-90atom% Ni and 10-50atom% Fe to obtain a material for a sputtering target forming a soft magnetic thin film having superior characteristics even in an atmosphere having a relatively low degree of vacuum or in case where only short-time presputtering is carried out as pretreatment.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Application This invention relates to a highly stable target material with respect to atmosphere fluctuations for Fe-Ni soft magnetic thin films used in thin film heads, etc. The present invention relates to a target material that exhibits extremely high stability against fluctuations in the sputtering atmosphere, exhibits excellent soft magnetic properties, and has no variation in the soft magnetic properties of sputtered thin films after being formed.

Background Art Fe-Ni soft magnetic thin film, for example, about 80% Ni −
A soft magnetic thin film made of permalloy whose main component is Fe.
For backing layers of perpendicular magnetic recording media and magnetic recording! is used for the core and yoke of membrane heads, including MO) fo
Permalloy or No-Cl permalloy containing TO and Cu is frequently used.

Sputtering is usually frequently used as a method for forming this thin film. In this sputtering method, a voltage is applied between the anode of the base material and the poles of the permalloy thin film of the desired composition and the target material of the same material, and the atoms on the target surface are driven out by cations, which adhere to the base material and the desired surface. This is a method of forming a permalloy 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 magnetism, it is necessary to strictly control the sputtering atmosphere conditions during thin film formation, and the ultimate vacuum The degree is 2xlO
-8 Torr or less, preferably 1x 10-6 Torr
It is necessary to maintain a high degree of vacuum below r.

In order to maintain a high degree of vacuum, the inner wall of the vacuum chamber is heated to release gas, moisture, etc. adhering to the inner wall of the vacuum chamber, or a shutter is used to heat the inner wall before forming a thin film on the target substrate. It was necessary to perform the operation for a long time to attach the thin film to other targets.

However, even if the atmosphere is extremely strictly controlled as described above, the magnetic properties of the permalloy thin film may deteriorate significantly due to the influence of the outside air humidity during work, or even if a compensating leak occurs. There was a problem that variations in characteristics occurred between each.

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

On the other hand, the target materials used to obtain permalloy thin films have been improved mainly to improve sputtering efficiency, to improve cooling efficiency, and to improve material utilization efficiency. No target material has been proposed that takes stability against fluctuations, etc. into consideration.

Furthermore, in Japanese Patent Publication No. 47-290690@, a magnetic alloy for magnetic recording and reproducing heads with high magnetic permeability and high hardness is proposed, which is obtained by adding positive to the NL Fe alloy for the purpose of high hardness. The above-mentioned known thin films and target materials, including those described above, do not take into account fluctuations in the sputtering atmosphere and reduction in pressure, as well as stabilization of the magnetic properties of the formed sputtered thin film, and none of them suffer from the above-mentioned problems. This problem could not be solved, and in order to stably obtain the soft magnetic properties of the resulting thin film, extremely strict atmosphere control was required during thin film formation.

Purpose of the Invention The object of the present invention is to provide a sputtering target material that can provide a soft magnetic thin film with excellent characteristics even under relatively limited ultimate vacuum or atmospheric conditions where only a short pre-sputtering operation is performed. In particular, we have solved the drawbacks of conventional target materials that cause significant deterioration and large variations in magnetic properties even with slight variations in the atmospheric conditions, and have stabilized thin films that exhibit excellent soft magnetic properties. The objective is to provide a target material for soft magnetic thin films that is highly stable against atmospheric fluctuations.

Structure and Effects of the Invention This invention was developed as a result of various studies aimed at creating a target material for soft magnetic thin films that can stably obtain excellent soft magnetic properties.
The so-called bar 70 component composition is mainly composed of i and Fe, including Mn, Cr, V, Nb, Ti, and Ti.

By specifically containing one or more of Zr, Hr, Si, Al, and Ge, extremely high stability can be achieved without being affected by changes in sputtering atmosphere conditions or relatively adverse conditions. This work was completed after discovering that a soft magnetic thin film having excellent soft magnetic properties could be obtained.

That is, in this invention, Ni 40 atomic % to 90 atomic %,
The main component is 10 atomic % to 50 atomic % Fe, t(n,
Cr, V.

Nb, Dina, Ti, Zr, [, Si, Al, G
The object of the present invention is to provide a target material with high stability of thin film magnetic properties against fluctuations in sputtering atmosphere, which is characterized by containing 0.5 at.% to 15 at.% of at least one of e.

In addition, this invention includes Ni40 atomic % to 90 atomic %, Fe
10 at% to 50 at% of the main component and Ho as a subcomponent
.

Contains at least 15 atomic % or less of at least one of W, Co, and Cu;
, Ta, Ti, Zr, )If.

This target material contains 0.5 to 15 at % of at least one of Si, Al, and Ge, and exhibits high stability of thin film magnetic properties against variations in sputtering atmosphere.

The soft magnetic thin film target material according to the present invention is characterized by its unique composition, and if it has a specific composition, it will have the following effects. That is, as is clear from the examples, the obtained thin film is a conventional permalloy.

It has superior magnetic properties compared to MO permalloy, and is also less sensitive to atmospheric conditions during sputtering, resulting in lower coercive force and permeability of the resulting soft magnetic thin film, even with lower vacuum degrees and shorter pre-sputtering times. There is little deterioration in magnetic properties such as magnetic coefficient, and it has extremely high stability against the atmosphere during sputtering, and the obtained thin film remains the same even after heat treatment after thin film formation. It goes without saying that even more excellent magnetic properties can be stably obtained if extremely strict atmosphere control is carried out during sputtering.

Therefore, on an industrial mass production scale, it is easy to control the atmosphere during sputtering, and even when the atmospheric conditions change within or between lots during long-term operation or when continuously sputtering films, etc., variations in magnetic properties can be avoided. This has the effect that a thin film with a small amount of carbon can be obtained at low cost.

In this invention, the target material used is one that has been alloyed in advance to the desired composition, but if alloying is difficult or rolling is difficult and it cannot be formed into the desired shape, the target material may be a binary system or contain subcomponents. It is also possible to use a composite target material as in the example in which the above-mentioned additive elements are completely bent or alloy chips are placed or embedded on the permalloy alloy target.

In general, the magnetic properties of the soft magnetic thin film obtained using the target material according to the present invention can be improved by heat treatment in the same way as ordinary permalloy thin films.
When holding or slowly cooling at a temperature below 00℃, NL3
It is desirable that a transition element capable of suppressing the formation of a regular lattice of Fe is included.

Reason for limitation of the invention The target material for a soft magnetic thin film of this invention contains Ni and Fe.
The main components are Hn, Cr, V, Nb, Ta
, Ti, Zr.

At least one of Hf, Si, Al, and Ge is added to 0.
It is characterized by a content of 5 at.% to 15 at.%, which makes it easy to control the atmosphere during sputtering on an industrial scale, and makes it possible to produce thin films with less variation in magnetic properties even under changes in atmospheric conditions at low cost. It has the effect that can be obtained. Although there are many unknown points regarding the mechanism by which this effect is obtained, it is thought to be approximately 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 properties of permalloy. It is not clear in what form this oxygen exists within the film, but in the thin film of this invention, due to the presence of the above-mentioned additive elements that have a greater affinity for oxygen than Ni and Fe, the oxygen is present within the film. It is thought that the oxygen contained causes the original magnetic properties of the permalloy thin film to be expressed without directly affecting N1 and Fe.

However, Mo as a binary permalloy or a subcomponent,
Compared to Ni and Fe such as W, Co, and Cu, conventional target materials that have little difference in affinity with oxygen at high temperatures, or conversely, contain only elements with low affinity, are not affected by the above oxygen. It is thought that the magnet reacts sensitively to even the slightest deterioration of the atmosphere, causing deterioration of the magnetic properties.

Therefore, in this invention, in order to obtain the effects of the above elements, In, Cr, V, Nb, Ta, Ti
, zr, Hr.

It is necessary to contain at least 0.5 atomic % or more of at least one of Si, Al, and Ge, preferably 2 atomic %.
As mentioned above, the content is preferably 4 atomic % or more. However, if the above elements are contained in an amount exceeding 15 atomic %, the saturation magnetic flux density will drop significantly, which is undesirable. Good. Further, the containing layer may be appropriately selected in consideration of the saturation magnetic flux density, the stability of desired magnetic properties in the thin film formation atmosphere, and the like.

The above additive elements are Ni and F, which are the basic components of permalloy.
e is Ni40 at% to 90 at%, Fe10 at% to
Although the effect is exhibited in a thin film in the range of 50 atomic %, the same effect is exhibited in a thin film containing any of Mo, W, Co, or Cu as a subcomponent as described above.

The magnetic properties of the soft magnetic thin film obtained with the target material according to the present invention are a coercive force of 1008 or less.

EXAMPLE The following three types of targets were prepared for the formation of a thin film for convulsions. The composition below is shown in wt%.

(1)79.7Ni -5)io-Fe (diameter 100
mm, thickness 3.5+nm) (2) As shown in Figure 1, (
79.78i same as 1) -5) Si chip (11) on 1o-Fe target material (10) (thickness 0.6 mm
Composite target (3) 79.9Ni -4,9Nb -2,l5i-F with nine pieces arranged radially
e (diameter 100 mm, thickness 3.5 mm) The above target material (1) is for comparison of the conventional composition.
(2×3) target material is according to this invention.

An RF magnetron sputtering device is used as the sputtering device, and the substrate has a thermal expansion coefficient of 98×10 near the lowest temperature.
-7/'C, thickness 0.9nvnX25mmX25mm
Using glass of the same size and water cooling the substrate holder, the maximum temperature of the substrate is 50°C to 55° for any sputtering.
It was held at C.

The sputtering conditions are high vacuum (A) and low vacuum (B).
The experiments were carried out under the conditions shown in Table 1 below, and the coercive force of the easy magnetization axis of the various thin films obtained was investigated using a BH tracer.
Obtained the results in the table.

Margins below Table 1 Table 2 In Table 2, a, c, and e are for high vacuum degrees (A), b, d, and f are for low vacuum degrees (B), and a, b
is a comparative thin film made of the target material (1), and c and d are thin films of the invention made of the composite target material (2), e and f.
This is the case of the thin film of the present invention using the target material (3).

In Table 2, the composition formulas listed in two rows a to f are the target material in the upper row and the thin film composition in the lower row.
Since the error is expected to be on the order of %, it is determined that there is no large difference in composition between thin films formed using the same target material.

There was a significant difference in the magnetic properties of the comparative thin film when the thin film formation conditions were high vacuum (a) and low vacuum. This shows an increase in coercivity of more than 13 times, indicating that a slight deterioration in the atmosphere during thin film formation causes a significant deterioration in magnetic properties.

On the other hand, in the case of the thin film according to the present invention, there is a much smaller difference between the thin film forming conditions between high vacuum and low vacuum than in the comparative example. That is, in comparing C and d, C
The coercive force of 0.80 s increases by only about 2.5 times that of 208 of d, and furthermore, there is almost no difference in coercive force between e and f, despite the deterioration of the thin film formation atmosphere. Both were 0.3Oθ.

As is clear from Table 1, Si or Nb and Si
The permalloy thin film target material of the present invention containing
It is insensitive to the atmospheric conditions during sputtering, and even with lower vacuum degrees and shorter sputtering times, the magnetic properties such as coercive force and magnetic permeability of the obtained soft magnetic thin film are less likely to deteriorate, and it is less sensitive to the atmospheric conditions during sputtering. It can be seen that it has extremely high stability.

Example 2 Using the same sputtering apparatus as Example 1, using three types of alloy target materials: 79Ni -4,5Nb-Fe1 79Ni -7Nb-Fe1 79.78i -5No-Fe,
Four types of thin films according to the present invention and a conventional No permalloy thin film were prepared by sputtering under the same conditions as shown in Table 1.

The composition of the obtained thin film was measured using an X-ray microanalyzer and an iser, the coercive force of the easy magnetization axis was measured using a BH tracer, and the magnetic permeability of the difficult magnetization axis was measured using a figure-eight coil. Table 3 shows the sputtering conditions including the ultimate vacuum degree and pre-sputtering time. Note that the magnetic permeability is indicated by the layer height value.

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 5x
Even if it is manufactured in a bad atmosphere of about 10-6 Torr,
Compared to the case of 1x 10-6 Torr vacuum, there is almost no deterioration in coercive force and magnetic permeability.

Further, the a film made of the target material of the present invention containing about 8% Nb has an ultimate vacuum degree of 5.3x 10-6 Torr.
In an atmosphere as bad as R, the pre-sputtering time is halved.
It can be seen that even when manufactured in minutes, it has better magnetic properties than the comparative example.

Therefore, a thin film made of the target material of the present invention has superior magnetic properties compared to a thin film made of conventional target materials, and the above-mentioned excellent properties can be stably obtained even if the atmospheric conditions for forming the thin film vary widely. It is clear that

Table 3 Example 3 a, b, and C shown in Table 2 obtained in Example 1.

Using the dI7)g film, heat treatment was performed for 500'CX 1 hour in a vacuum of 1X10-4 TOrr, followed by slow cooling, and the magnetic permeability of the difficult magnetization axis (10 mm Z) was applied.
.

was measured using a figure 8 coil. Table 4 shows the measurement results (highest values).

In the case of the No permalloy thin film of the comparative example, the magnetic permeability of the thin film A produced under the poor atmospheric conditions of low vacuum is only 176, which is the magnetic permeability of the thin film A produced under high vacuum.

However, in the thin film obtained from the Si-containing target material according to the present invention, the thin film d under poor atmospheric conditions is approximately 172
It is clear that the properties after heat treatment are not easily affected by the atmospheric conditions during sputtering.

Table 4

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the composite target material in Example 1. 10-79.7N1-5Ho-Fe target material, 1l
-3i chip.

Claims (1)

[Claims] 1 The main components are 40 at% to 90 at% of Ni, 10 to 50 at% of Fe, and Mn, Cr, V, Nb, Ta, and Ti.
, Zr, Hf, Si, Al, and Ge in an amount of 0.5 to 15 at %, the target material exhibiting high stability of thin film magnetic properties against sputtering atmosphere fluctuations. 2 Contains a main component of 40 at% to 90 at% Ni, 10 at% to 50 at% Fe, and 15 at% or less of at least one of Mo, W, Co, and Cu as a subcomponent, and further contains M
n, Cr, V, Nb, Ta, Ti, Zr, Hf, Si,
0.5 atomic % to 15 at least one of Al and Ge
Target material with high stability of thin film magnetic properties against fluctuations in sputtering atmosphere, characterized by containing atomic%.