JPH0251205A - Multilayer ferromagnetic substance - Google Patents

Abstract

PURPOSE:To ensure highly saturated magnetic flux density, high magnetic permeability and low magnetostriction constant while contriving the improvement of a soft magnetic characteristic and heat-resistant stability by using a nitride (containing nonequilibrium phase) of silicon of a specific composition range as an intermediate layer together with iron magnetic layer and laminating these on a board alternately. CONSTITUTION:In a multilayer ferromagnetic body, an iron magnetic material used as a magnetic layer has highly saturated magnetic flux density and high permeability and small magnetostriction constant is used. Further, in an intermediate layer, a nitride of silicon expressed by usual SixNy (containing nonequilibrium phase) is used. It is necessary that x and y of the nitride of the silicon satisfies 0.4<=x/y<=1.1. The magnetic layer and the intermediate layer are laminated alternately and the thickness of a single layer is decreased to preferably increase the number of laminating layers. Further, the value of x/y at SixNy of the intermediate layer can be controlled by selecting the composition of a deposition material, the content of nitrogen in an environmental gas, a degree of deposition vacuum, deposition rate and the like.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a novel multilayer ferromagnetic material. More specifically, the present invention has excellent characteristics such as high saturation magnetic flux density, high magnetic permeability, and low magnetostriction constant, as well as good soft magnetic properties and heat resistance stability. The present invention relates to a multilayered ferromagnetic material suitable for use as a multilayer ferromagnetic material.

2. Description of the Related Art In recent years, in magnetic recording and reproducing devices such as VTRs, the recording signal density and frequency have been increased. So-called metal tapes using ferromagnetic metal powder, and so-called vapor-deposited tapes in which ferromagnetic metal materials are deposited on a base film by means such as vapor deposition, are being put into practical use.

Since such a magnetic recording medium has a high coercive force, the head material of the magnetic head used for recording and reproduction is required to have a high saturation magnetic flux density. In addition, in order to improve the resolution of the magnetic head, it is necessary to reduce the thickness of the magnetic pole of the head, and in order to prevent magnetic saturation at the tip of the magnetic pole that occurs due to this, a magnetic material with a high saturation magnetic flux density is used. Furthermore, in the perpendicular magnetic recording system, for example, the main pole of a single-pole magnetic head for perpendicular magnetic recording is extremely thin, about 0.2 μm, so it easily becomes magnetically saturated during recording and reproduction. To avoid this, a magnetic head material with a high saturation magnetic flux density is required.

On the other hand, the magnetic head material needs to have high magnetic permeability from the viewpoint of recording and reproducing efficiency of the bed, and desirably has a magnetostriction constant close to zero.

Various kinds of magnetic materials having such high saturation magnetic flux density, high magnetic permeability, and low magnetostriction constant have been developed so far, such as iron-nickel alloy (permalloy),
Iron-aluminum-silicon alloy (sendust), iron-
Silicon-based alloys (JP-A-57-172703), iron-chromium-based alloys containing 0.3 to 3.8% by weight of chromium (JP-A-63-60256), and the like are known.

However, since these iron-based magnetic materials have a large magnetocrystalline anisotropy constant, when used as a single layer film, the volume of crystal grains is large and the resulting softness is greatly affected by the anisotropic dispersion of magnetization. The disadvantage is that the magnetic properties are significantly degraded. In order to improve this drawback, it is desirable to make the crystal grains finer and suppress the anisotropic dispersion of magnetization due to the crystal grains. Attempts have been made to improve the soft magnetic properties by thinning the crystal grains and making the crystal grains finer.

Examples of multilayer magnetic materials using ferrite in the magnetic layer include those made of iron-based magnetic layers and intermediate layers made of silicon dioxide (Japanese Patent Application Laid-open No. 1983-58806), iron-chromium alloys, etc. (Japanese Unexamined Patent Application Publication No. 1983-1989
60256), which use silicon dioxide, a non-magnetic material, in the intermediate layer have been known so far.

However, although such a multilayer magnetic material using silicon dioxide as an intermediate layer has a certain degree of excellent effect in improving soft magnetic properties, it is not necessarily sufficient in terms of heat resistance stability. This is because, at temperatures of about 200 to 600° C., the characteristics deteriorate due to diffusion bonding of the silicon dioxide with iron in the magnetic layer or expansion of crystal grains in the magnetic layer.

Problems to be Solved by the Invention Under these circumstances, the present invention solves the problem of high saturation magnetic flux density,
The purpose of this invention is to provide a multilayer ferromagnetic material having high magnetic permeability and low magnetostriction constant, as well as good soft magnetic properties and heat resistance stability.

Means for Solving the Problems As a result of intensive research to develop a multilayered ferromagnetic material having the above-mentioned excellent characteristics, the present inventors have found that, together with the iron-based magnetic layer, the intermediate layer has a specific composition range. It was discovered that the object could be achieved by using silicon nitride (including non-equilibrium phase) and alternately layering these on a substrate, and based on this knowledge, the present invention was completed.

That is, in the present invention, (A) an iron-based ferromagnetic layer and (B) a general formula SixNy (including a non-equilibrium phase) ... (I) (
(X and y in the formula are numbers satisfying the relationship of formula 0.4≦x/y≦1.1) The object of the present invention is to provide a multilayered ferromagnetic material.

The present invention will be explained in detail below.

In the multilayer ferromagnetic material of the present invention, the iron-based magnetic material used as the magnetic layer is not particularly limited as long as it has a high saturation magnetic flux density, high magnetic permeability, and a small magnetostriction constant. Iron-based magnetic materials commonly used in magnetic thin films for conventional magnetic heads can be used. Examples of such iron-based magnetic materials include permalloy, Fa-5i-
AI2 alloy, Fe-5L-Ru alloy, Fe-5L alloy, Fe-Ni-Mo alloy, Fe-Ga-5L alloy,
Examples include Fe-Cr alloys, and these may be used alone or in combination of two or more.

For the intermediate layer in the multilayered ferromagnetic material of the present invention, a silicon nitride represented by the general formula SixNy (including non-equilibrium phase) (I) is used. It is necessary that X and y of this silicon nitride have a relationship that satisfies 0.4≦x/y≦1.1. If the x/y value deviates from the above range, the effect of improving the soft magnetic properties will not be sufficiently exhibited.

Such silicon nitride is stable even at temperatures of about 300 to 600°C, and like silicon oxide, it is thought to have diffused with iron in the magnetic layer, resulting in little deterioration in properties.

There are no particular restrictions on the substrate used for the multilayered ferromagnetic material of the present invention, and substrates that are conventionally used for magnetic thin films for magnetic heads, such as glass or plastic, with a polymer layer that is cured by ultraviolet rays, etc. may be used. A substrate made of a transparent material such as acrylic resin, styrene resin, polycarbonate resin, vinyl acetate resin, vinyl chloride resin, or polyolefin resin, or a substrate made of an opaque material such as aluminum or ferrite can be used.

The multilayered ferromagnetic material of the present invention is obtained by laminating the above-mentioned magnetic layers and intermediate layers alternately on these substrates, and it is preferable to increase the number of laminated layers by decreasing the thickness of the single layer. , from the point of view of economy and workability, the thickness of the magnetic layer is usually 200 to 1
000 people, the thickness of the middle layer is selected in the range of 10 to 100 people, the number of laminated layers is in the range of 4 to 140 layers, and the total thickness is in the range of 0.4 to 3 μm. is preferred.

In the present invention, there are no particular limitations on the method for forming the magnetic layer and the intermediate layer, and any method may be used from among the methods normally used for forming thin films, such as vacuum evaporation, sputtering, ion blating, and CVD. The following methods can be selected and used. Also, the middle layer 5ixNy
The x/y value in can be controlled by selecting the composition of the vapor deposition raw material, the nitrogen content in the atmospheric gas, the vapor deposition vacuum degree, the vapor deposition rate, etc.

Effects of the Invention The multilayer ferromagnetic material of the present invention is a highly saturated material in which ferromagnetic layers made of iron-based materials and intermediate layers made of silicon nitride of a specific composition are alternately laminated on a substrate. It has excellent characteristics such as magnetic flux density, high magnetic permeability, and low magnetostriction constant, as well as good soft magnetic properties and heat resistance stability, and is suitably used as a magnetic film of a magnetic head.

Examples Next, the present invention will be explained in more detail with reference to examples.
The present invention is not limited in any way by these examples.

The magnetic permeability, coercive force, and composition of the single layer film of the obtained multilayered ferromagnetic material were determined as follows.

(1) Magnetic permeability μiac Determine by applying a ferrite scope to the film surface so that the measurement magnetic field is applied in the direction of the difficult axis of magnetization, and measuring the inductance using an impedance analyzer with a magnetic field of 3 mOe and a measurement frequency of 5Ml1z. two.

(2) Coercive force t(c(Oe) Measurements were made using a thin film histroscope.

(3) Single layer film composition E PMA (Electron Probe M
It was determined by the micro-analysis method.

Example: Iron-silicon alloy target containing 1.7 wt. 1% silicon and S
Sputtering was performed alternately in a magnetic field of 3000e (Oersted) using an RF magnetron sputtering device using i, N, and N targets to form a magnetic layer made of an iron-silicon magnetic alloy with a thickness of 500 mm on the substrate. 25 Six
A multilayer film having a total thickness of about 0.8 μm was formed by alternately stacking 15 intermediate layers made of Ny. At this time, a crystallized glass (trade name 7 Otoceram) with a plate thickness of 1.1 mm was used as the substrate.

The sputtering conditions were as follows: argon pressure 15 mTorr, input power 3.
2 W/cm”, substrate temperature 300°C, SixNy
A mixed gas of argon and nitrogen in various proportions was used to form the layer, the pressure was 15 mTorr, and the input power was 1.9 W7c.
m'' and the substrate temperature was 300°C.

Note that the iron-silicon magnetic alloy film was formed in an argon gas atmosphere, and the SixNy film was formed in a mixed gas atmosphere of argon and nitrogen.

Moreover, SixN in the multilayer layer obtained in this way
In order to determine the composition of the y layer, separately, the plate thickness 1. ] mm barium borosilicate glass (trade name 7059) under the same conditions as above except that the substrate temperature was 150° C., and the composition of this film was determined.

Figure 1 shows the nitrogen content (volume %) in the mixed gas and the Si
The relationship with the x/y value in the xNy layer is shown in a graph. Furthermore, Fig. 2 shows the relationship between the x/y value in the SixNy layer and the coercive force [t(c(Oe)] of the multilayer film, and Fig. 3 shows the relationship between the x/y value in the SixNy layer and the coercive force [t(c(Oe)]).
The relationship between the x/y value and magnetic permeability (μ1ac) in the y layer is shown.

From these figures, it can be seen that the x/y value in the SixNy layer is 0.
It can be seen that it has good soft magnetic properties (low coercive force, high magnetic permeability) in the range of 4 to 1.1.

In addition, FIGS. 4 and 5 show the intermediate layer Sioz and Si3N.
.

This is a graph examining the heat resistance when using conventional 5iO
It can be seen that the multilayer film using the Si3N layer for z is thermally stable.

[Brief explanation of the drawing]

Figures 1, 2, and 3 respectively show the relationship between the nitrogen content in the mixed gas and the x/y value in the SixNy layer for the multilayer ferromagnetic material created in the example of the present invention. A graph showing the relationship between the x/y value and the coercive force in the SixNy layer, and a graph showing the relationship with the magnetic permeability. FIGS. 4 and 5 are graphs examining the heat resistance stability when 5ioz and SiJ+ were used for the intermediate layer.

Claims (1)

[Claims] 1. On a substrate, (A) an iron-based ferromagnetic layer and (B) a general formula Si
_xN_y (including non-equilibrium phase) (x and y in the formula are numbers that satisfy the relationship of 0.4≦x/y≦1.1) A multilayered ferromagnetic material characterized by alternating layers of ferromagnetic materials.