CN103781933B - Alloy for soft-magnetic thin-film layer on perpendicular magnetic recording medium, and sputtering-target material - Google Patents

Abstract

The invention provides an alloy for a soft magnetic film layer in a perpendicular magnetic recording medium with low coercive force. The alloy contains the following components: one or more selected from Ti, Zr, Hf, Nb, Ta and B; one or two of W and Sn (wherein, a part of one or two of W and Sn Or all of them may be replaced by one or two of V and Mn); if necessary, one or more selected from Al, Cr, Mo, Si, P, C and Ge; 1 or 2 kinds; and the balance contains Co and Fe, and satisfies in at.%: (1) 6≤Ti%+Zr%+Hf%+Nb%+Ta%+B%/2≤24; (2) Zr%+Hf%≤14; (3)3≤W%+Sn%≤19; (4)0.20≤Fe%/(Fe%+Co%)≤0.90; (5)3≤W%+ Sn%+V%+Mn%≤19 (wherein, V%+Mn% can be 0); (6) 0≤Al%+Cr%+Mo%+Si%+P%+C%+Ge%≤9 and (7) 0≤Ni%+Cu%≤5.

Description

Alloys and sputtering targets for soft magnetic thin film layers in perpendicular magnetic recording media

Cross-reference of related applications

This application claims priority based on Japanese Patent Application No. 2011-178187 for which it applied on August 17, 2011, The entire disclosure content is taken in this specification as a reference.

technical field

The invention relates to an alloy for a soft magnetic thin film layer in a perpendicular magnetic recording medium with low coercive force and a sputtering target material for making the thin film of the alloy.

Background technique

In recent years, the progress of magnetic recording technology has been remarkable. In order to realize the large capacity of the drive device, the high recording density of the magnetic recording medium has been progressed. The recording method is being practical.

The so-called perpendicular magnetic recording method is a magnetic recording method in which the easy axis of magnetization is oriented in a direction perpendicular to the medium surface of the magnetic film of the perpendicular magnetic recording medium, and is a method that achieves high recording density. Furthermore, in the perpendicular magnetic recording system, a two-layer recording medium having a magnetic recording film layer and a soft magnetic film layer having improved recording sensitivity has been developed. A CoCrPt-SiO ₂ -based alloy is generally used for this magnetic recording film layer.

On the other hand, the existing soft magnetic film layer requires ferromagnetism and non-crystallinity, and further requires high saturation magnetic flux density, high corrosion resistance, high hardness, etc. according to the application and use environment of the perpendicular magnetic recording medium. characteristic. For example, as in Japanese Unexamined Patent Application Publication No. 2008-260970 (Patent Document 1), a ferromagnetic element Co with high corrosion resistance is used as a matrix, and an amorphous promoter represented by Zr is added in order to improve amorphousness. Elemental layer. In addition, in JP 2008-299905 A (Patent Document 2), a high saturation magnetic flux density is obtained by adding Fe, and a high hardness is obtained by adding B.

Furthermore, in addition to the above-mentioned characteristics that have been required so far, it is also required to be an alloy for soft magnetic films having a low coercive force. In recent hard disk drives, by improving the magnetic head for reading and writing and adjusting the magnetic flux density of the soft magnetic alloy to optimize the exchange coupling magnetic field between the soft magnetic film and the Ru film, it is possible to write with a lower magnetic flux than before. On the other hand, in the soft magnetic film disposed under the recording film, the magnetization can be reversed even with a lower write magnetic flux than a high saturation magnetic flux density saturated with a high write magnetic flux. turn, thereby effectively forming a low coercive force.

prior art literature

patent documents

Patent Document 1: Japanese Patent Laid-Open No. 2008-260970

Patent Document 2: Japanese Patent Laid-Open No. 2008-299905

Contents of the invention

The inventors of the present invention conducted a detailed study on the influence of alloying elements on the coercive force of the alloy for soft magnetic films of perpendicular magnetic recording media. Coercive soft magnetic alloy. In addition, it was found that V and/or Mn are effective as auxiliary additive elements for reducing the coercive force. In addition, it has also been clarified that excessive addition of Zr and/or Hf, which are conventionally used amorphization promoting elements, increases the coercive force.

In addition, although the most important feature of the present invention can also be clarified in the examples described later, the effect of reducing the coercive force with respect to the amount of reduction of the saturation magnetic flux density was evaluated in detail for various additive elements, and it was found that W and/or Sn have the highest effect. In addition, it is also clear that V and/or Mn, next to W and/or Sn, have a high coercive force reducing effect.

Therefore, an object of the present invention is to provide an alloy for a soft magnetic thin film layer in a perpendicular magnetic recording medium having a low coercive force and a sputtering target for producing a thin film of the alloy.

According to one embodiment of the present invention, a kind of alloy is provided, and it is the alloy for soft magnetic film layer in perpendicular magnetic recording medium, and described alloy comprises following composition:

- one or more selected from Ti, Zr, Hf, Nb, Ta and B;

- 1 or 2 of W and Sn (wherein, a part or all of 1 or 2 of W and Sn can also be replaced by 1 or 2 of V and Mn);

- One or more selected from Al, Cr, Mo, Si, P, C and Ge as needed;

- 1 or 2 kinds of Ni and Cu contained as needed; and

- the balance contains Co and Fe,

And, in terms of at.%, satisfy the following formula:

(1) 6≤Ti%+Zr%+Hf%+Nb%+Ta%+B%/2≤24;

(2) Zr%+Hf%≤14;

(3) 3≤W%+Sn%≤19;

(4) 0.20≤Fe%/(Fe%+Co%)≤0.90;

(5) 3≤W%+Sn%+V%+Mn%≤19 (wherein, V%+Mn% can be 0);

(6) 0≤Al%+Cr%+Mo%+Si%+P%+C%+Ge%≤9; and

(7) 0≤Ni%+Cu%≤5.

According to another embodiment of the present invention, there is provided a sputtering target comprising the alloy described above.

detailed description

The present invention will be specifically described below. Unless otherwise specified, "%" or a number without a unit means at% in this specification.

The invention provides an alloy for a soft magnetic thin film layer in a perpendicular magnetic recording medium, the alloy comprising (comprising) the following components: one or more selected from Ti, Zr, Hf, Nb, Ta and B; one or more of W and Sn One or two kinds (wherein, a part or all of one or two of W and Sn can also be replaced by one or two of V and Mn); optionally selected from Al, Cr, Mo 1 or more of Si, P, C, and Ge; optionally 1 or 2 of Ni and Cu; and the balance contains Co and Fe, preferably consisting essentially of only these elements (consisting essentially of), more preferably consist of only these elements (consisting of). And, the alloy of the present invention satisfies the following formula in at.%:

(1) 6≤Ti%+Zr%+Hf%+Nb%+Ta%+B%/2≤24;

(2) Zr%+Hf%≤14;

(3) 3≤W%+Sn%≤19;

(4) 0.20≤Fe%/(Fe%+Co%)≤0.90;

(5) 3≤W%+Sn%+V%+Mn%≤19 (wherein V%+Mn% can be 0);

(6) 0≤Al%+Cr%+Mo%+Si%+P%+C%+Ge%≤9; and

(7) 0≤Ni%+Cu%≤5.

Next, reasons for limiting the component composition of the present invention will be described.

One or more elements selected from Ti, Zr, Hf, Nb, Ta, and B are essential elements for promoting amorphization to satisfy 6≤Ti%+Zr%+Hf%+Nb%+Ta%+B% The amount of /2≤24 is contained in the alloy. In addition, B has an amorphization promoting effect and a saturation magnetic flux density reducing effect of about 1/2 compared with other elements, so it is treated as B/2 in this formula. In addition, if Ti%+Zr%+Hf%+Nb%+Ta%+B%/2 is less than 6, the amorphization promotion effect is insufficient, and if it exceeds 24, the amorphization promotion effect is saturated, and the magnetic saturation is saturated. Flux density decreases excessively, so its range is 6-24, preferably 8-18, more preferably 9-14.

Although Zr and/or Hf are elements with a high effect of promoting amorphization, they increase the coercive force at the same time. If Zr%+Hf% exceeds 14, the coercive force will increase, so the upper limit is 14 (ie Zr%+Hf%≤14), preferably 12, more preferably 8.

W and/or Sn are essential elements for increasing the coercivity reduction effect relative to the reduction ratio of the saturation magnetic flux density, and are the most important addition elements in the present invention. However, if the added amount of W%+Sn% is less than 3%, the effect of reducing the coercive force will be insufficient, and if it exceeds 19%, the effect will be saturated, and the saturation magnetic flux density will be excessively reduced, so the range is 3 to 19%. (ie 3≤W%+Sn%≤19), preferably 4-17, more preferably 6-14. In addition, the detailed mechanism of this high coercive force lowering effect is not clear, but it is expected to affect the lowering of the saturation magnetostriction constant.

Co and Fe are essential elements for giving it a high saturation magnetic flux density. However, if Fe%/(Fe%+Co%) is less than 0.20 or exceeds 0.90, a high saturation magnetic flux density cannot be obtained. Therefore, the range of Fe%/(Fe%+Co%) is 0.20 to 0.90, preferably 0.25 to 0.70, more preferably 0.30 to 0.65.

V and/or Mn are elements second only to W and/or Sn in effectively lowering the coercive force, and can be substituted with part or all of W and/or Sn. However, if W%+Sn%+V%+Mn% is less than 3, the effect of reducing the coercive force will be insufficient. On the other hand, if it exceeds 19, the effect of reducing the coercive force will be saturated, and the saturation magnetic flux density will be excessively low. reduce. Therefore, the range of W%+Sn%+V%+Mn% is 3-19, preferably 4-17, more preferably 6-14.

One or more elements selected from Al, Cr, Mo, Si, P, C, and Ge will not have a great influence on the reduction of the coercive force, but it is an arbitrary element that can be added for adjustment of the saturation magnetic flux density . However, if the total amount exceeds 9%, the saturation magnetic flux density will decrease excessively, so the upper limit of Al%+Cr%+Mo%+Si%+P%+C%+Ge% is 9, preferably 4, more preferably Preferably 0.

Ni and/or Cu are arbitrary elements that can be added for adjustment of the saturation magnetic flux density. However, since the coercive force will increase, the upper limit is 5% (ie Ni%+Cu%≤5), preferably 3, and more preferably 0.

Example

Hereinafter, the present invention will be specifically described by way of examples.

Generally, a soft magnetic thin film layer in a perpendicular magnetic recording medium is obtained by sputtering a sputtering target having the same composition as that, and forming a film on a glass substrate or the like. Here, the thin film formed by sputtering is rapidly cooled. On the other hand, as the test materials of Examples and Comparative Examples in the present invention, quenched ribbons produced by a single-roll liquid quenching device were used. Here, the effect of the composition of the thin film actually quenched by sputtering and formed into a film on various characteristics is evaluated simply by using a liquid quenched ribbon.

As the production conditions of the quenched ribbon, 30 g of the raw material weighed according to the specified composition is arc-melted in a decompressed argon gas using a water-cooled copper mold with a diameter of 10 mm and a length of about 40 mm to make the melted base material of the quenched ribbon. Regarding the production conditions of the quenched ribbon, the molten base material is placed in a quartz tube with a diameter of 15 mm in a single roll method, and the diameter of the furnace (Japanese: 出汤) nozzle is set to 1 mm. Tapping was carried out under conditions of a rotational speed of 3000 rpm (300 mm in diameter) and a gap of 0.3 mm between the copper roll and the tapping nozzle. The furnace temperature is the temperature at which each molten base metal has just melted (Japanese: 银け流). The quenched ribbon produced in this way was used as a test material, and the following items were evaluated.

As an evaluation of the coercive force reduction effect relative to the decrease in saturation magnetic flux density, using a vibrating sample type coercive force meter, a quenching tape was attached to the sample stand with double-sided tape, and an initial external magnetic field of 144kA/m was used. to measure coercive force. Next, the saturation magnetic flux density was measured using a VSM device (vibrating sample magnetometer) under the conditions of an applied magnetic field of 1200 kA/m and a weight of the test material of about 15 mg. From these measurement results, the ratio of the decrease in coercive force to the decrease in saturation magnetic flux density before and after the addition of various elements [(decrease in coercive force)/(decrease in saturation magnetic flux density )] to evaluate. Therefore, a larger value indicates that a greater coercive force reduction effect can be obtained with a smaller saturation magnetic flux density reduction.

On the other hand, as an evaluation of the amorphousness of the quenched ribbon, when the X-ray diffraction pattern of an amorphous material is generally measured, no diffraction peaks are observed and a halo pattern peculiar to amorphous is obtained. In addition, when not completely amorphous, although diffraction peaks can be observed, the peak height becomes lower than that of a single crystal material, and a halo pattern can also be observed. Therefore, the amorphousness was evaluated by the following method.

The test material was pasted on the glass plate with double-sided tape, and the diffraction pattern was obtained by using an X-ray diffraction device. At this time, the test material was pasted on the glass plate so that the measurement surface would be the surface in contact with the copper roll of the quenched ribbon. The X-ray source is Cu-kα ray, and the scanning speed is 4 per minute. measured under the conditions. In this diffraction pattern, the case where a halo pattern can be observed is marked as ◯, and the case where no halo pattern is observed is marked as x, and the amorphousness was evaluated. First, two basic compositions were selected, a certain amount of additional elements were added respectively, and the coercive force reduction effect based on the type of added elements was studied. The results are shown in Tables 1 and 2.

[Table 1]

Table 1

Note) ※: A minus sign indicates a composition in which the coercive force increases due to the addition of elements

Table 1 shows the effect of the type of added element with 86(50Co50Fe)-8Zr-6B as the basic composition (evaluation when the added amount is constant). In addition, this symbol represents 43Co-43Fe-8Zr-6B.

【Table 2】

[Table 2]

Table 2

Note) ※: A minus sign indicates a composition in which the coercive force increases due to the addition of elements

Table 2 shows the effect of the type of added element with 87(35Co65Fe)-3Ti-5Zr-3Nb-2Ta as the basic composition (evaluation when the added amount is constant). In addition, this symbol represents 30.45Co-56.55Fe-3Ti-5Zr-3Nb-2Ta.

As shown in Table 1, the addition of W and/or Sn is the most effective in reducing the coercive force, followed by the addition of V and/or Mn is effective. In addition, the addition of Cr, Mo, Al, C, Si, P, and/or Ge cannot significantly change the coercive force. In addition, it can be seen that the addition of Ni and/or Cu significantly increases the coercive force. In addition, Table 2 also shows exactly the same effect as Table 1. The addition of W and/or Sn is the most effective in reducing the coercive force, and the addition of V and/or Mn is second most effective. In addition, the addition of Cr, Mo, Al, C, Si, P, and/or Ge cannot significantly change the coercive force. In addition, it was found that the addition of Ni and/or Cu significantly increases the coercive force.

From the test results shown in Tables 1 and 2, it can be seen that the reduction effect of coercive force is (W, Sn)>(V, Mn)>(Cr, Mo, Al, C, Si, P, Ge)>(Ni , Cu), W, Sn, V and/or Mn reduce the coercivity, Cr, Mo, Al, C, Si, P and/or Ge make the change of coercivity small, Ni and/or Cr will make The coercive force is greatly increased. From this result, it can be seen that the order of the upper limit of addition in the present invention is defined as (W, Sn)=(V, Mn)>(Cr, Mo, Al, C, Si, P, Ge)>(Ni, Cu) , especially the upper limit of Ni and/or Cu, which has a greater adverse effect on increasing the coercive force, needs to be strictly controlled.

[table 3]

table 3

Note) The underline is outside the conditions of the present invention

Next, in order to quantitatively study the upper limit of the addition amount of each element, test materials with various basic components and test materials with various elements added to them were produced, and the coercive force, saturation magnetic flux Density, amorphous and saturation flux density tests. The results are shown in Table 3.

Here, in Table 3, the additive elements are substituted with the basic components (Co+Fe). That is, the basic composition of No. 1 in Table 3 is shown as 72.8Co-18.2Fe-8Zr-1Ta, and the composition of No. 1 with additional elements added is shown as 70.4Co-17.6Fe-8Zr-1Ta-3W. In addition, it is predicted that the ratio of Co and Fe has an influence on the coercive force. The purpose of this experiment is to clarify the influence of the added elements on the coercive force purely. Therefore, the ratio of Co and Fe and the amount of other basic components are fixed. The evaluation is carried out under the premise of composition. Hence the expression.

In addition, in Table 3, the decrease in coercive force and the decrease in saturation magnetic flux density represent the range from the coercive force and saturation magnetic flux density of the test material with each basic component to the coercive force and saturation magnetic flux density of the test material with each additional element added. The reduction in force and saturation magnetic flux density, and the evaluation of amorphousness and saturation magnetic flux density represent the characteristics of the test material to which the additive element was added. In addition, the case where [coercive force decrease (A/m)]/[saturation magnetic flux density decrease (T)] is 15 or more is set as ◎, 8 or more and less than 15 is set as ○, -7 or more and The case of less than 8 was made into Δ, and the case of less than -8 was made into x. In addition, the case where the saturation magnetic flux density was 0.3T or more was made into (circle), and the case of less than 0.3T was made into x.

As shown in Table 3, Nos. 1 to 27 are examples of the present invention, and Nos. 28 to 40 are comparative examples. In Comparative Example No. 28, since the Fe content was low, the saturation magnetic flux density was poor. In addition, in Comparative Example No. 29, since Co was not contained, the saturation magnetic flux density was inferior. In Comparative Example No. 30, since the content of W, an element promoting low coercive force, was low, the coercive force lowering effect was insufficient. In Comparative Example No. 31, since the content of Sn, an element that promotes the reduction of the coercive force, was low, the effect of reducing the coercive force was insufficient.

In Comparative Example No. 32, since the content of the element W that promotes low coercive force is large, the saturation magnetic flux density is poor. In Comparative Example No. 33, since the content of the single element Hf, which promotes amorphousness, was low, the amorphous property was poor, and the coercive force was so high that it exceeded the evaluable range of the measuring device used. In addition, it is generally known that the coercivity increases remarkably when a large amount of crystalline phases are formed in the amorphous phase. In Comparative Example No. 34, since the sum of the contents of Zr, Ta, and B/2, which promotes amorphousness, is high, the saturation magnetic flux density is poor. In Comparative Example No. 35, since the sum of the contents of Zr and Hf, elements that promote amorphousness and cause an increase in coercive force, is high, the coercive force lowering effect is insufficient.

In Comparative Example No. 36, since the sum of the contents of W, V, and Mn, elements promoting low coercive force, was high, the saturation magnetic flux density was poor. In Comparative Example No. 37, since the sum of the contents of V and Mn, elements promoting low coercive force, was high, the saturation magnetic flux density was poor. In Comparative Example No. 38, since the sum of the contents of the elements Al, Cr, and Si used for adjustment of the saturation magnetic flux density is high, the saturation magnetic flux density is poor. In Comparative Example No. 39, since the Cu element content was high, the effect of reducing the coercive force was poor. In Comparative Example No. 40, since the content of the Ni element was high, the effect of reducing the coercive force was poor.

As described above, according to the present invention, it is possible to achieve saturation with low coercive force without deteriorating saturation magnetic flux density and amorphousness due to the addition of elements W, Sn, V, and Mn that promote low coercive force. An alloy for a soft magnetic thin film layer in a perpendicular magnetic recording medium having an excellent balance of magnetic flux density, amorphousness, and low coercive force, and a sputtering target for producing a thin film of the alloy.

Claims (9)

1. an alloy, which is an alloy for a soft magnetic film layer in a perpendicular magnetic recording medium, and the alloy comprises the following components: ‐One or more selected from Ti, Zr, Hf, Nb, Ta and B; ‐One or both of W and Sn, where part or all of one or both of W and Sn can also be replaced by one or both of V and Mn; ‐One or more selected from Al, Cr, Mo, Si, P, C and Ge as needed; ‐One or both of Ni and Cu contained as needed; and ‐The balance contains Co and Fe, And, in terms of at.%, satisfy the following formula: (1) 9≤Ti%+Zr%+Hf%+Nb%+Ta%+B%/2≤24; (2) Zr%+Hf%≤8; (3) 3≤W%+Sn%≤19; (4) 0.20≤Fe%/(Fe%+Co%)≤0.90; (5) 3≤W%+Sn%+V%+Mn%≤19, wherein, V%+Mn% can be 0; (6) 0≤Al%+Cr%+Mo%+Si%+P%+C%+Ge%≤9; and (7) 0≤Ni%+Cu%≤5, In addition, the ratio of the decrease in coercive force to the decrease in saturation magnetic flux density, that is, [decrease in coercive force]/[decrease in saturation magnetic flux density] is 8 or more, and the saturation magnetic flux density is 0.3T or more, Wherein, the decrease in saturation magnetic flux density is the difference between the saturation magnetic flux density of the alloy satisfying the formulas (1), (2) and (4) and the saturation magnetic flux density of the alloy satisfying the formulas (1)-(4) , the coercive force reduction amount is the difference between the coercive force of the alloy satisfying the formulas (1), (2) and (4) and the coercive force of the alloy satisfying the formulas (1) to (4). 2. The alloy according to claim 1, wherein a part or all of one or more of W and Sn is replaced by one or more of V and Mn, thereby satisfying 0<V%+Mn%. 3. The alloy according to claim 1, wherein the alloy contains one or more selected from Al, Cr, Mo, Si, P, C and Ge, thereby satisfying 0<Al%+Cr%+Mo %+Si%+P%+C%+Ge%≤9. 4. The alloy according to claim 2, wherein the alloy contains one or more selected from Al, Cr, Mo, Si, P, C and Ge, thereby satisfying 0<Al%+Cr%+Mo %+Si%+P%+C%+Ge%≤9. 5. The alloy according to any one of claims 1 to 4, wherein the alloy contains one or both of Ni and Cu, thereby satisfying 0<Ni%+Cu%≦5. 6. An alloy according to any one of claims 1 to 4, wherein the alloy consists solely of: ‐One or more selected from Ti, Zr, Hf, Nb, Ta and B; ‐One or both of W and Sn, where part or all of one or both of W and Sn can also be replaced by one or both of V and Mn; ‐One or more selected from Al, Cr, Mo, Si, P, C and Ge as needed; ‐One or both of Ni and Cu contained as needed; and ‐The balance is Co and Fe. 7. The alloy of claim 5, wherein the alloy consists solely of: ‐One or more selected from Ti, Zr, Hf, Nb, Ta and B; ‐One or both of W and Sn, where part or all of one or both of W and Sn can also be replaced by one or both of V and Mn; ‐One or more selected from Al, Cr, Mo, Si, P, C and Ge as needed; ‐One or both of Ni and Cu contained as needed; and ‐The balance is Co and Fe. 8. The alloy according to claim 1, wherein a part or all of one or more of W and Sn, is Sn, wherein a part of Sn may be replaced by one or more of V and Mn, or is W and Sn, wherein a part of one or more of W and Sn may be replaced by one or more of V and Mn, all of W may be replaced by one or more of V and Mn, and all of Sn may be replaced by one or more of V and Mn. Can be replaced by Mn. 9. A sputtering target comprising the alloy according to any one of claims 1-8.