JPH0368744A - Thin magnetic film - Google Patents

Abstract

PURPOSE:To produce a thin magnetic film having high magnetic permeability and saturation magnetic flux density in a high-frequency region by forming a thin film by a sputtering method by using an Fe-Ni-Co alloy with a specific composition as a target. CONSTITUTION:High-purity Ni, Fe, Nb, Ta, and Co are blended in the prescribed proportion, which is melted and cast in vacuum. The resulting Fe-Ni-Co-Nb-Ta alloy is worked into a target, and a thin film having a composition consisting of, by weight, <2% Co, 44-55% (Ni+Co), 0.5-5.5%, in total, of Nb and/or Ta, and the balance Fe is formed on a glass substrate in a reduced-pressure Ar-gas atmosphere, e.g., by a sputtering method. If necessary, 0.1-2%, in total, of one or more elements among Mo, V, Cr, W, and Cu for improving magnetic properties, 0.001-0.5% of one or more elements among Ti, Zr, and Hf as grain-refining elements, or 0.001-2%, in total, of one or more elements among Ag, Au, Ru, Rh, Pd, and Pt as corrosion resistance-improving elements can be incorporated to the above thin film.

Description

DETAILED DESCRIPTION OF THE INVENTION <A> Industrial Application Field The present invention relates to a magnetic thin film, and particularly to a magnetic thin film with excellent high frequency magnetic properties.

The present invention also relates to a magnetic thin film that is used in recording media, magnetic heads, and magnetic cores and has excellent high-frequency magnetic properties, and in particular,
For example, 8III video tape recorder (VTR),
Thin-film heads for high-density recording and playback such as digital audio tape recorders (DAT), high-density digital displays, and high-density data systems (ODD), as well as metal-in-gap (formerly G) heads and magnetoresistive (MR) heads.
) The present invention relates to a magnetic thin film that is used as a magnetic head such as a magnetic head, as a base of a perpendicular magnetic recording medium, and as a magnetic core of electronic equipment used in the high frequency range of a switching power supply.

(Koto) Prior art The progress of magnetic materials in the field of magnetic recording is remarkable, and research is currently active on recording media and magnetic heads that use magnetic thin films to increase density. Also, in order to increase the size and performance of electronic equipment, Operating frequencies are gradually moving toward higher frequencies.
The magnetic core materials used are also becoming thinner.

Ferrite is currently the most widely used material in the high frequency range. However, ferrite has a low saturation magnetic flux density, making it unsuitable for high-density recording, and its magnetic permeability decreases significantly in the ultra-high frequency range.

Therefore, magnetic thin films with high saturation magnetic flux density are desired as magnetic heads for high-density recording, and N1-Fe-based alloys, Fe
Magnetic thin films such as -5i-AI alloys and Co-based amorphous alloys are being put into practical use.

(C) Problems to be Solved by the Invention However, the Ni-Fe alloy is
Magnetic properties are inferior to Co-based alloys and Co-based amorphous alloys. Furthermore, although a Fe-5i-^1 alloy can produce a magnetic thin film with excellent magnetic properties under optimal conditions, there are problems with reproduction methods.

Further, although the Co-based amorphous alloy has excellent properties in the form of a thin film, there is a problem in that the magnetic properties deteriorate during the heating process when manufacturing a thin film magnetic head.

Furthermore, all of the above-mentioned materials have a problem in that their magnetic permeability decreases significantly in a high frequency region of MHz or higher.

Although intensive research is currently being carried out to solve these problems, the inventors have not yet achieved success. In order to solve this problem, we conducted many experiments on metal-based crystalline magnetic thin films from the viewpoint of high saturation magnetic flux density and thermal stability. We investigated the magnetic permeability in the high frequency range of crystalline magnetic thin films formed using targets doped with various elements, and found that the composition was 75 to 82% by weight of nickel (Ni), niobium (Nb), and tantalum. High-frequency magnetism characterized in that the total content of one or two types of (Cho a) is 1 to 8% by weight, molybdenum (No. For the purpose of inventing a magnetic thin film with excellent characteristics, see Japanese Patent Application No. 284461/1983. ).

Following these inventions, the present inventors further developed 75 to 83 from the viewpoint of high saturation magnetic flux density, thermal stability, and reproducibility.
We conducted more experiments on crystalline magnetic thin films formed using targets containing various elements on a weight% nickel-iron (Ni-Fe) alloy base material, and investigated the magnetic permeability in the high frequency range. , the composition is 2% by weight or less of cobalt, 75 to 83% by weight of nickel in total with cobalt, and 1 to 8% in total of one or more types of niobium and tantalum.
0.01 to 2% by weight of one or more of molybdenum, vanadium, chromium, tungsten, and copper (Cu) in a total amount of 0.01 to 2% by weight, and one or two of titanium, zirconium, and hafnium. The inventors have discovered that a magnetic thin film consisting of a total of 0.01 to 2% by weight of the above, with the remainder of iron and a small amount of impurities maintains high magnetic permeability up to a high frequency range and can be produced with good reproducibility. (Special application 1986
-66283), and the even earlier invented Ni
- As a result of intensive studies to improve the corrosion resistance of Fe-Nb alloys, the composition was found to be 2% by weight or less of cobalt, 73 to 82% by weight of nickel in total with cobalt, and 1 to 10% in total of one or two of niobium and tantalum. 8% by weight, one or more of molybdenum, vanadium, chromium, tungsten, and copper in a total amount of 0.01 to 2% by weight, one or more of titanium, zirconium, and hafnium in a total amount of 0. .01 to 2%, further comprising one or more of silver, gold, ruthenium, rhodium, palladium, and platinum in a total amount of o, ooi to 2% by weight, and the remaining iron and a small amount of impurities. We have invented a magnetic thin film that maintains high magnetic permeability up to high frequencies, has good corrosion resistance, and can be manufactured with good reproducibility. (Patent application 1983-797
(See No. 41) However, both of these magnetic thin films are made of Ni.
Saturation magnetic flux density is 7.000~8.0O due to high content
The disadvantage was that it was low as OG.

The present invention aims to solve this problem.

(d) Means and actions for solving problems.

The present invention relates to improvements to conventional magnetic thin films, and includes a novel magnetic r! which has high permeability in the high frequency range and even higher saturation magnetic flux density. The purpose is to provide I membranes.

The present inventors believe that the high magnetic permeability in the MHz band of the previously invented Ni-Fe-Nb alloy thin film is due to local anisotropy due to the refinement of crystal grains and improvement in the degree of crystal grain orientation due to the addition of Nb. It was revealed that this was due to a significant reduction in

Reduction of local anisotropy by grain refinement and improvement of orientation degree is expected to have a large effect in the composition range with small magnetostriction (λ). Therefore, in the present invention, Ni with high saturation magnetic flux density and small λ
The composition range of the -Fe system was intensively studied.

As a result, in a small range of λ where cobalt is 2% by weight or less and the total amount of nickel and cobalt is 40 to 55% by weight, 13
It has been found that a saturation magnetic flux density of ,000 Gauss or more and high magnetic permeability can be obtained.

As in the previous invention, a decrease in local anisotropy was observed in the thin film that had high magnetic permeability due to Nb addition.

In addition, the present inventors have demonstrated the improvement of magnetic properties by the addition of molybdenum, vanadium, chromium, tungsten, and copper, the effect of titanium, zirconium, and hafnium on the reproducibility of magnetic properties, and the effects of silver, gold, ruthenium, rhodium, palladium, It was also found that the same effects as the previously invented Ni-Fe-Nb system were found, such as the corrosion resistance improvement effect of platinum.

That is, in the present invention, the composition is 2% or less of cobalt by weight,
Nickel is characterized by a total content of 40 to 55% with cobalt, niobium and one or more of tantalum in a total content of 0.5 to 5.5%, and the remainder substantially consisting of iron and inevitable impurity components. The present invention is directed to a magnetic thin film having excellent high-frequency magnetic properties.The present invention also provides a magnetic thin film having a weight ratio of 2% or less of cobalt, 40 to 55% of nickel in total with cobalt, and 0.5% in total of one or more of niobium and tantalum. 5 to 5.5%, one or more of molybdenum, vanadium, chromium, tungsten, and copper in a total amount of 0.1 to 2%, and one or more of titanium, zirconium, and hafnium in a total amount of 0.001 to 0.5%, with the remainder consisting essentially of iron and unavoidable impurity components. 2% or less of cobalt, 40 to 55% of nickel in total with cobalt, 0.5 to 5.5% in total of one or more of niobium and tantalum, any of silver, gold, ruthenium, rhodium, palladium, and platinum A magnetic thin film with excellent high-frequency magnetic properties characterized by containing one or more types in a total amount of o, oot ~ 2%, with the remainder consisting essentially of iron and unavoidable impurity components. In the invention, the composition is 2% or less of cobalt by weight,
The total amount of nickel and cobalt is 40 to 55%, the total amount of one or more of niobium and tantalum is 0.5 to 5.5%, and the total amount of one or more of molybdenum, vanadium, chromium, tungsten, and copper is included. 0.011 to 2% in total, one or more of titanium, zirconium, and hafnium in a total amount of 0.001 to 0.5%, and one or two of silver, gold, ruthenium, rhodium, palladium, and platinum. A magnetic thin film having excellent high-frequency magnetic properties is characterized in that the total amount of the above components is 0.001 to 2%, and the remainder is substantially composed of iron and unavoidable impurity components.

In the magnetic thin film of the present invention, cobalt (CO) is contained in an amount of 2% by weight or less. Nickel (Ni) has a total of 40 to 55% by weight of the nickel and 2% by weight or less of cobalt.
It is contained so that the magnetostriction is small within the range of .

Outside this range, the magnetic permeability and saturation magnetic flux density of the obtained magnetic thin film are both lower than those within this range. Further, in the present invention, it is preferable that the content of cobalt is 2% by weight or less, since this contributes to an increase in the saturation magnetic flux density and Curie temperature without significantly affecting the magnetic permeability.

Niobium and tantalum are elements with very similar properties, and in the case of the present invention, they have the same effect of reducing local anisotropy. Therefore, in the present invention, any one of niobium and tantalum can be used as niobium and tantalum, but they can also be used in combination. Regarding tantalum content, as the content increases, the magnetic permeability of the magnetic thin film in the high frequency region increases;
If it exceeds 5.5% by weight, the saturation magnetic flux density will decrease and the magnetic permeability will decrease significantly, so the upper limit should be set at 5.5% by weight.
It is preferable that the amount is 0.5% by weight or less, and since these effects are small if the amount is less than 0.5% by weight, it is preferable to set the lower limit to 0.5% by weight.

Molybdenum (No), vanadium (V), chromium (C
r), tungsten (old and !771 (Cu)) has no effect on their own, but Nb or T
When added at the same time as a or at the same time as Nb and Ta, it has the effect of further increasing the effect of Nb or Ta alone and the effect of Nb and Ta coexisting, and also has the effect of improving the corrosion resistance of the thin film. . However, if added in large amounts, the saturation magnetic flux density will decrease, so molybdenum (No),
When vanadium (■>), chromium (Cr), tungsten (old) and copper (Cu) are contained, when one type of element among these elements is contained, the amount of each of the elements is 2% by weight. It is preferable that the content is as follows.However, even when these elements are contained in combination, it is preferable that the upper limit of the total content of these elements is 2% by weight.Also, in any case, for these elements, Since no effect can be expected if the content is less than 0.1% by weight, the lower limit of the content is preferably 0.1% by weight.

Titanium (Ti), zirconium (Zr), and hafnium (Hf) are effective in refining the target's crystal grains and reducing the gas content, so using a target containing these elements will result in excellent magnetic properties. It is preferable because IJII can be stably obtained. Such an effect appears when each element is contained alone or in combination of two or more in a total amount of 0.001% or more, but if it exceeds 0.5%, the saturation magnetic flux density decreases, so the content range is 0
．． The amount is preferably 0.001 to 0.5% by weight.

In addition, rare earth elements such as yttrium (Y), lanthanum (La), and cerium (Ce) include Ti, Zr, and Hf.
Therefore, it can be used as long as the total content of each element alone or two or more elements is 0.5% by weight or less. Silver (^g>, gold (^u>), ruthenium (Ru), rhodium (Rh), palladium (Pd)
) and platinum (pt), the higher the content, the higher the corrosion resistance and magnetic permeability.

However, from the economic point of view, silver (^g) and gold (^u
), ruthenium (Ru), rhodium (Rh), palladium (Pd), and platinum (Pt), and when containing one or more of these elements, the The total content is preferably 2% by weight or less, and since no effect can be expected if it is less than 0,001% by weight, the content is preferably in the range of 0,000% to 2% by weight.

As described above, the magnetic thin film of the present invention has a composition of 2% by weight or less of cobalt and 40 to 40% of nickel in total with cobalt.
A magnetic thin film consisting of 55% by weight, one or both of niobium and tantalum in a total amount of 0.5 to 5.5% by weight, the remainder iron and a small amount of impurities;
molybdenum, vanadium, chromium, tungsten, copper,
A magnetic thin film containing a total amount of 0.1 to 2% by weight of one or more of titanium, zirconium, and hafnium, and a total of 0.001 to 0.5% of one or more of titanium, zirconium, and hafnium; Furthermore, in addition to the above composition of the magnetic thin film,
It is a magnetic thin film containing one or more of silver, gold, ruthenium, rhodium, palladium, and platinum in a total amount of 0.001 to 2% by weight, but manganese (Mn),
When using deoxidizers such as silicon (Si), aluminum (^l), calcium (Ca), and magnesium (Hg) alone, they can be used in an amount of 0.5% by weight or less, and two or more types of elements When used in combination, they can be used if the total amount is 1% or less.

The magnetic thin film in the present invention can be formed by a thin film deposition method such as a vacuum evaporation method, a sputter evaporation method, or an ion blating method. However, it is preferable to fabricate the film by forming a film on a suitable insulating material by a sputter deposition method in an argon atmosphere, that is, a sputtering method, because the operation is simple. In this case, the sputtering is controlled at 3 to 25 mTorr (3X 10-Col 25X 10
It is preferable to carry out the process under an argon pressure maintained in the range of -'Torr) because a thin film with excellent magnetic properties can be obtained.

In the present invention, the thin film formed on a suitable insulator is
It has a thickness of μ- or less, and can be a single layer or a large number of 71 layers with an insulator interposed therebetween.

The magnetic thin film of the present invention can be used for 8 mm VTR, DAT, tl
It can be used for various purposes such as thin film heads of DDs and the like, and in particular, it can also be used for various purposes in place of the Ni--Fe alloy thin film. For example, an excellent HIG head can be manufactured by forming the magnetic thin film of the present invention on ferrite, as an intermediate layer of a conventional G head, or as a yoke of an HR head, or as an intermediate layer of a Co - It can be advantageously used in various applications as a base for perpendicular magnetic recording media such as Cr.

(e) Examples Examples of embodiments of the present invention will be described below, but the present invention is not limited in any way by these explanations and exemplifications.

Hereinafter, - in the example will be explained in detail. Using electrolytic nickel (Ni), electrolytic iron (Fe), metallic niobium (Nb), tantalum (Ta), and metallic molybdenum (No) as raw materials, predetermined amounts were mixed, 3 kg was melted in a vacuum, and a mold with a diameter of 60 mm was formed. This ingot was hot forged and then machined to produce a target with a thickness of 3I and a diameter of 70L.

Using this target, a thin film with a thickness of 3,000 to 6,000 A was formed on a glass substrate by DC magnetron sputtering and RF sputtering in an argon atmosphere within a pressure range of 3 to 60 nTorr.

These thin films were heat-treated at a temperature in the range of 200 to 500° C. during film formation. Table 1 shows the magnetic property values of the thin film after this heat treatment.

The magnetic properties of this thin film are significantly affected by target composition, sputtering conditions, and heat treatment conditions, but Table 1
The values are the best characteristic values obtained for each composition.

As shown in Table 1, all of the alloys of the present invention have a high saturation magnetic flux density (Bs) of 13 KG or more, and have improved effective magnetic permeability (μeff) compared to the comparative alloys.

(The following is a blank space) Table 1 Furthermore, since the magnetic thin film according to the present invention is crystalline, it has excellent thermal stability, and the special product does not deteriorate during the heating process during the manufacturing of the thin film head.

(Effects of the invention) The magnetic thin film according to the invention has a high saturation magnetic flux density and excellent high frequency characteristics, and also has excellent thermal stability and corrosion resistance.

Thus, for example, 8 m/m VTR, DAT and I
(For thin film heads for high-density recording and playback such as DD,
Also, for example, for use in magnetic heads such as HTG heads and MR heads, or as bases for perpendicular magnetic recording media.
It is also very useful as a magnetic core for electronic equipment used in high frequency ranges such as switching power supplies, and as a magnetic material used in ultra high frequency ranges that will be increasingly needed for power supplies in the future. Very useful when magnetic flux density is required.

Claims (4)

[Claims] (1) The composition is 2% or less cobalt by weight, 40 to 55% nickel in total with cobalt, 0.5 to 5.5% in total of one or more of niobium and tantalum, and the balance is substantially iron. A magnetic thin film with excellent high-frequency magnetic properties, characterized by a composition consisting of and unavoidable impurity components. (2) The composition is 2% or less cobalt by weight, 40 to 55% nickel in total with cobalt, 0.5 to 5.5% in total of one or more of niobium and tantalum, molybdenum,
0.1 to 2% in total of one or more of vanadium, chromium, tungsten, and copper; 0.001 to 0.5% of one or more of titanium, zirconium, and hafnium; A magnetic thin film with excellent high frequency magnetic properties characterized in that the remainder consists essentially of iron and unavoidable impurity components. (3) The composition is 2% or less of cobalt by weight, 40 to 55% of nickel in total with cobalt, 0.5 to 5.5% in total of one or more of niobium and tantalum, silver, gold, ruthenium, A magnetic thin film with excellent high-frequency magnetic properties characterized by containing one or more of rhodium, palladium, and platinum in a total amount of 0.001 to 2%, with the remainder consisting essentially of iron and unavoidable impurity components. . (4) The composition is, by weight, 2% or less of cobalt, 40 to 55% of nickel in total with cobalt, 0.5 to 5.5% in total of one or more of niobium and tantalum, molybdenum, vanadium, One or more of chromium, tungsten and copper in a total amount of 0.1 to 2%, one or more of titanium, zirconium and hafnium in a total amount of 0.001 to 0.5%, silver, gold, ruthenium,
A magnetic thin film with excellent high-frequency magnetic properties characterized by containing one or more of rhodium, palladium, and platinum in a total amount of 0.001 to 2%, with the remainder consisting essentially of iron and unavoidable impurity components. .