JP3495741B2 - Soft magnetic thin film - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soft magnetic thin film used for a magnetic head material and the like, and particularly to Fe, R
The present invention relates to improvement of soft magnetic characteristics of a soft magnetic thin film mainly containing u, Ga, and Si. 2. Description of the Related Art A soft magnetic thin film mainly composed of Fe, Ga and Si has been proposed by the present applicant in Japanese Patent Application Laid-Open No. 61-234509,
It is a material having the same magnetic permeability and coercive force as an alloy (so-called sendust) and having a significantly higher saturation magnetic flux density than an Fe-Al-Si alloy. The Fe-Ru-Ga-Si alloy to which Ru is added is a material having both corrosion resistance and abrasion resistance in addition to the above-mentioned characteristics, and is being studied as a magnetic head material for a high-quality VTR. I have. [0003] By the way, it is generally said that crystalline soft magnetic materials are superior in thermal stability to amorphous soft magnetic materials, and the above-mentioned Fe-Ru-Ga-Si Alloys are no exception. However, for example, in the case of a bulk-type magnetic head, a glass fusing step of about 550 ° C. is required for its production in order to obtain excellent reliability, and even after such a high-temperature heat treatment, excellent soft magnetic characteristics are obtained. Although it is required to exhibit, from such a viewpoint, the thermal stability of the Fe-Ru-Ga-Si alloy is not necessarily sufficient. Therefore, the present invention has a high saturation magnetic flux density,
Moreover, an object of the present invention is to provide a soft magnetic thin film that exhibits excellent soft magnetic properties even after heat treatment. It is a further object of the present invention to provide a soft magnetic thin film capable of fusing glass at a high temperature and realizing a highly reliable magnetic head. The inventors of the present invention have made intensive studies to achieve the above-mentioned object and found that Fe-Ru
-When forming a Ga-Si alloy film, nitrogen, oxygen and carbon are introduced to refine the crystal grains of the formed Fe-Ru-Ga-Si alloy film, thereby increasing the high saturation magnetic flux density. With the composition shown, it has been found that sufficient soft magnetic properties are exhibited even after heat treatment. [0006] The soft magnetic thin film according to the present invention, which has been completed based on these findings, (Fe _a Ru _{b
Ga c Si d) x N y} O z C w [ However, a, b, c,
d, x, y, z, and w represent the ratio (atomic%) of each element. Whose composition range is 68 ≦ a ≦ 90 0.1 ≦ b ≦ 10 0.1 ≦ c ≦ 15 10 ≦ d ≦ 25 80 ≦ x ≦ 98 0 <y ≦ 200 0 <z ≦ 200 <w ≦ 20 a + b + c + d = 100 x + y + z + w = 100 2 ≦ y + z + w ≦ 20, and the average crystal grain size is 600 ° or less. [0007] According to an aspect of the present invention, which has been completed based on these findings, (Fe _a Ru _{b
Ga c Si d) x N y} O z C w [ However, a, b, c,
d, x, y, z, and w represent the ratio (atomic%) of each element. Whose composition range is 68 ≦ a ≦ 90 0.1 ≦ b ≦ 10 0.1 ≦ c ≦ 15 10 ≦ d ≦ 25 80 ≦ x ≦ 98 0 ≦ y ≦ 200 0 ≦ z ≦ 200 ≦ w ≦ 20 a + b + c + d = 100 x + y + z + w = 100 2 ≦ y + z + w ≦ 20 and the average crystal grain size is not more than 600 °. Further, the soft magnetic thin film according to the present invention is formed by a technique such as sputtering, vacuum deposition, or ion plating, but nitrogen, oxygen and carbon are introduced, and the film forming conditions are adjusted appropriately. The average crystal grain size of the obtained soft magnetic thin film must be 600 ° or less. The average crystal grain size greatly affects the soft magnetic properties of the obtained soft magnetic thin film. If the average crystal grain size exceeds 600 °, it is difficult to reduce the coercive force. As a method of introducing nitrogen, oxygen and carbon at the time of film formation, for example, in the case of nitrogen and oxygen, nitrogen gas and oxygen gas may be introduced into the film formation atmosphere, respectively, or the target may be nitrided. And an oxide may be used. Similarly, when carbon is introduced, a gas containing carbon as a constituent element such as hydrocarbon, carbon monoxide, carbon dioxide, or the like may be introduced into the film formation atmosphere, and further, carbon pellets or carbides may be targeted. May be used. When a Fe—Ru—Ga—Si alloy film is formed, nitrogen, oxygen and carbon are introduced to refine crystal grains,
By setting the average crystal grain size to 600 ° or less, the soft magnetic properties after the heat treatment are significantly improved, and the high saturation magnetic flux density is maintained. Hereinafter, specific examples to which the present invention is applied will be described in detail based on experimental results. EXPERIMENTAL EXAMPLE 1 In this experimental example, oxygen was introduced into an Fe-Ru-Ga-Si alloy film, and the influence on the average crystal grain size and soft magnetic characteristics was examined. First, the soft magnetic thin film was formed by Fe-Ru-Ga-
This was performed by DC sputtering using a Si alloy target (diameter 100 mm). Oxygen was introduced by introducing a mixed gas of Ar and oxygen (O ₂ ) into the sputtering atmosphere. The sputtering conditions at the time of film formation are as follows. Introduced gas: Ar + O ₂ Sputter gas pressure: 0.51 Pa Input power: 300 W Film thickness: 3 μm Various soft magnetic thin films were formed by changing the amount of oxygen introduced under the above sputtering conditions, and the average crystal grain size thereof In addition, the coercive force Hc was measured. The average crystal grain size is calculated based on the X-ray diffraction pattern from the half width of the main peak to S
It was determined by the equation of Charrer. This value almost coincided with the value obtained from observation of the film with a transmission electron microscope. Further, the coercive force Hc was measured by a BH loop tracer. FIG. 1 shows (Fe _76.7 Ru ₄ Ga _5.5 Si).
_13.8 ) In a soft magnetic thin film having a composition of _100-z O _z (0 ≦ z ≦ 20), it is shown that the average crystal grain size changes by changing the amount of oxygen, and the coercive force Hc changes accordingly. This is illustrated. The coercive force Hc shows a sharply small value near the average crystal grain size of about 600 °. Then, next, for a representative sample,
Table 1 shows the measured values of the average crystal grain size and the coercive force Hc.
All of these samples were prepared by changing the amount of oxygen introduced according to the above-mentioned sputtering conditions, but the sample 7 was formed by increasing the sputtering gas pressure. (Sputter gas pressure: 3 Pa) As is clear from this table, Sample 1 was prepared by introducing an appropriate amount of oxygen to reduce the average crystal grain size.
4 to 4 (corresponding to the examples) have a coercive force Hc of 1 or less after annealing at 550 ° C., and exhibit good soft magnetic properties even after heat treatment. On the other hand, Sample 5, in which oxygen was not introduced and the average crystal grain size was large, showed a large coercive force Hc of 2.0 after heat treatment. Similarly,
Even for sample 7, the coercive force H was high for sample 7 in which the average crystal grain size was large due to inappropriate conditions even if oxygen was introduced.
c is a high value, and deterioration of the soft magnetic characteristics is observed. Further, in Sample 6, in which the amount of introduced oxygen is too large, the average crystal grain size has a small value, but the soft magnetic properties are deteriorated due to excess oxygen, and the coercive force Hc is also a high value. Experimental Example 2 In this experimental example, nitrogen was introduced into the Fe-Ru-Ga-Si alloy film, and the influence on the average crystal grain size and soft magnetic characteristics was examined. The conditions for forming the soft magnetic thin film were the same as those in Experimental Example 1, but the gas introduced during sputtering was Ar + N ₂ . Even when nitrogen was introduced, the average crystal grain size changed similarly to the case of oxygen, and the coercive force Hc changed accordingly. Table 2
The measured values of the average crystal grain size and the coercive force Hc of a representative sample are shown below. Sample 13 was formed at a sputtering gas pressure of 3 Pa, similarly to Sample 7 described above. [Table 2] The same tendency as in the case of oxygen is observed when nitrogen is introduced. Samples 8 to 11 in which an appropriate amount of nitrogen is introduced to reduce the average crystal grain size have good softness even after heat treatment. Demonstrated magnetic properties. On the other hand, in Sample 12 in which the amount of nitrogen introduced is too large and in Sample 13 in which the average crystal grain size is large even when nitrogen is introduced,
The coercive force Hc was a high value. EXPERIMENTAL EXAMPLE 3 In this experimental example, carbon was introduced into the Fe-Ru-Ga-Si alloy film, and the influence on the average crystal grain size and soft magnetic characteristics was examined. The conditions for forming the soft magnetic thin film were the same as those in Experimental Example 1 except that the gas introduced during sputtering was Ar and Fe-Ru was used.
-Sputtering was performed by arranging carbon pellets on a -Ga-Si alloy target. Even when carbon was introduced, the average crystal grain size changed similarly to the case of oxygen, and the coercive force Hc changed accordingly. Table 3 shows the measured values of the average crystal grain size and the coercive force Hc of a representative sample. Sample 19 was formed at a sputtering gas pressure of 3 Pa, similarly to Sample 7 described above. [Table 3] When carbon is introduced to reduce the average crystal grain size, the same effect as in the case of oxygen can be obtained.
Samples 14 to 17 having a small average crystal grain size
Had a small coercive force Hc after heat treatment and were excellent in soft magnetic properties. In addition, it was confirmed that Sample 18 in which the amount of carbon introduced was too large and Sample 19 in which the average crystal grain size was large even when carbon was introduced had a high coercive force Hc after heat treatment and were inferior in performance as a soft magnetic thin film. . As is apparent from the above description, in the present invention, nitrogen, oxygen and carbon are introduced into the Fe-Ru-Ga-Si alloy film to make crystal grains fine. Therefore, the coercive force can be remarkably improved, and a soft magnetic thin film having excellent heat resistance and high saturation magnetic flux density can be provided. Therefore, a highly reliable glass fusing step becomes possible, and it is possible to realize a magnetic head which can cope with a high coercive force magnetic recording medium and has high reliability.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a characteristic diagram showing a relationship between an average crystal grain size and a coercive force Hc.

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Hiroyuki Omori               6-7-35 Kita Shinagawa, Shinagawa-ku, Tokyo               Knee Co., Ltd. (72) Inventor Kazuhiko Hayashi               6-7-35 Kita Shinagawa, Shinagawa-ku, Tokyo               Knee Co., Ltd. (72) Inventor Koichi Aso               6-7-35 Kita Shinagawa, Shinagawa-ku, Tokyo               Knee Co., Ltd.

Claims (1)

(57) [Claims] [Claim 1] _{(Fe a Ru b Ga c Si} d) x N y O
_z C _w [where a, b, c, d, x, y, z, and w represent the ratio (atomic%) of each element. ] Is represented by a composition formula
The composition range is 68 ≦ a ≦ 90 0.1 ≦ b ≦ 10 0.1 ≦ c ≦ 15 10 ≦ d ≦ 25 80 ≦ x ≦ 98 0 <y ≦ 200 0 <z ≦ 200 0 <w ≦ 20 a + b + c + d = 100 x + y + z + w = 100 2 ≦ y + z + w ≦ 20, and the average crystal grain size is 600 ° or less.