JPH0935935A - Manufacture of soft magnet film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method whereby a soft magnetic film of Fe-Si-Al alloy having high saturation magnetic flux density and high permeability can be produced. SOLUTION: In forming a soft magnetic film of an alloy magnetic material made of Fe, Si, Al and other fine elements on a non-magnetic oxide substrate by sputtering, dc sputtering is carried out supplying oxygen gas to the substrate periodically. A process of forming a layer A of magnetic film 50nm thick in the absence of the oxygen gas supply and a layer B of magnetic film 3nm thick in the presence of the oxygen gas supply is repeated to produce a soft magnetic film 3μm thick composed of the layers A and the layers B alternately stacked. The content of oxygen in the layer B of the soft magnetic film is 5-20% by atom, and preferably 11-17% by atom.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a soft magnetic film used for a magnetic head of a magnetic disk device for a computer.

[0002]

2. Description of the Related Art Conventionally, in the field of magnetic recording, a metal-based magnetic recording medium having a high coercive force and a residual magnetic flux density has come to be used with the increase in recording signal density. Further, it has been required that the core material of the magnetic head for reproduction has a high saturation magnetic flux density.

However, since the soft magnetic oxide ferrite most widely used as a core material is hard to obtain satisfactory characteristics, recently, a laminated magnetic layer using a soft magnetic thin film such as an Fe--Si--Al alloy is used. The head is rapidly gaining attention. In this laminated magnetic head, an alloy magnetic film of Fe-Si-Al or the like is formed on a non-magnetic oxide substrate of Co-Ni-O, Mn-Ni-O, hematite (α-Fe ₂ O ₃ ) or the like. A film having a film thickness of 10 μm is used.

In such a laminated magnetic head, since a magnetic film having a film thickness corresponding to the track width may be formed on the substrate by sputtering, the process for regulating the track width can be omitted, and a block such as a ferrite material can be omitted. Problems associated with processing the track width, such as in a magnetic head using a core material, are solved.

[0005]

In the Fe-Si-Al alloy, the composition that gives the highest magnetic permeability is the sendust composition (9.6 wt% Si, 5.5 wt% Al, balance F).
e). However, the saturation magnetic flux density in this composition is 10
It is about kG (k Gauss). Since the coercive force of the recording medium is increasing with the increase in recording density, it is considered that the recording ability is insufficient at a saturation magnetic flux density of about 10 kG.

Therefore, there is a method of reducing the Si concentration and the Al concentration in order to increase the saturation magnetic flux density. However, in this case, although the saturation magnetic flux density increases, the magnetic permeability decreases.

By the way, conventionally, as a method of manufacturing an alloy magnetic film, a method of performing sputtering while periodically introducing oxygen gas into a substrate is known (Japanese Patent Laid-Open No. 53-7549).
9, JP-A-61-233409, JP-A-2-9811
2, JP-A-6-290941).

For example, in Japanese Unexamined Patent Publication No. 6-290941, rf magnetron sputtering is carried out while introducing oxygen gas into a substrate periodically, magnetic thin film layers and insulating thin film layers are alternately laminated, and the insulating thin film layers are formed. Disclosed is an alloy magnetic film in which a magnetic thin film layer is covered with constituent substances and the like.

However, according to the study by the present inventor,
In order to increase the magnetic permeability, the magnetic interaction between Fe and Fe must be the whole film, and Fe must not be oxidized even in the magnetic layer into which oxygen is periodically introduced. In the rf magnetron sputtering of the above publication, the plasma is easily spread to facilitate the oxidation reaction, and the controllability of the oxidation state of the layer formed by introducing oxygen is poor. Therefore, the soft magnetic film is formed alternately with the layer in which oxygen is not introduced. Although it is possible to improve the magnetic permeability, the high magnetic permeability cannot be stably obtained.

An object of the present invention is to provide a manufacturing method capable of obtaining a soft magnetic film of an Fe-Si-Al alloy having a high saturation magnetic flux density and a high magnetic permeability.

[0011]

The above object can be achieved by the manufacturing method according to the present invention. In summary, the present invention provides:
In a method of manufacturing a soft magnetic film, which comprises forming a soft magnetic film of an alloy magnetic material containing Fe, Si, Al and other trace elements on a non-magnetic oxide substrate by sputtering, oxygen gas is periodically supplied to the non-magnetic oxide substrate. The method for producing a soft magnetic film is characterized in that dc sputtering is carried out while being supplied to the soft magnetic film.

According to the present invention, dc is added to the non-magnetic oxide substrate.
It is possible to perform dc sputtering while applying at least one of a bias and an rf bias, the dc bias is -15V to -50V, and the rf bias is 7W to 17W.
It can be.

In the soft magnetic film, the oxygen content of the soft magnetic film layer formed without supplying oxygen gas is 5 atomic% or less, and the soft magnetic film layer formed by introducing oxygen gas The oxygen content can be 5 atomic% or more and 20 atomic% or less. Further, the soft magnetic film layer formed without supplying oxygen gas in the soft magnetic film has a thickness of 20 nm to 150 n.
The thickness of the soft magnetic film layer formed by introducing oxygen gas can be 0.8 nm or more.

In the soft magnetic film according to the present invention, a layer of the soft magnetic film (hereinafter referred to as layer A) formed in a state where oxygen gas is not supplied near the non-magnetic oxide substrate, and oxygen gas is supplied near the substrate. Layer of the soft magnetic film (hereinafter referred to as B
And layers) are alternately laminated. Since the A layer, which represents most of the soft magnetic film, is sandwiched between the B layers, the crystal grains are fine even after the heat treatment, and the effective magnetocrystalline anisotropy becomes small, so that a good soft magnetic film is obtained. Become.

In the present invention, industrially general dc sputtering is used to form the soft magnetic film. However, since this dc sputtering does not spread plasma widely, the B layer formed under the supply of oxygen gas is It is possible to avoid excessive progress of the oxidation reaction of the elements therein. At the time of this dc sputtering, a dc bias and / or an rf bias is applied to the substrate separately from the sputtering voltage applied to the target, and the bias is selected within an optimum range, whereby Fe, which is the main element of the B layer, The oxidation state of Si and Al can be controlled.

In order to improve the soft magnetic characteristics of the magnetic film, all Fe in the B layer is in a metallic state, Si is in a partially oxidized state,
Al is preferably in a state in which most of it is oxidized, and when a B layer in such an oxidized state is obtained after heat treatment, a magnetic film having the best soft magnetic characteristics can be manufactured.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

In the present invention, a dc facing target sputtering apparatus was used for dc sputtering of the soft magnetic film. An Fe-Si-Al alloy was used as the target, and Co-Ni-O was used as the non-magnetic oxide substrate. As a substrate,
In addition, Mn-Ni-O or hematite (α-F
e ₂ O ₃ ) or the like can also be used.

In the above, the Co-Ni-O substrate is C
A non-magnetic oxide substrate containing oO / NiO as a main component, the composition of which is 0/100 <CoO / NiO (molar ratio) ≦ 80.
/ 20. Preferably, from the relationship of the thermal expansion coefficient of the metal magnetic film, 3/97 <CoO / NiO (molar ratio) ≦ 60
/ 40 is good, and the additive is, for example, 0 ≦ Al ₂ O ₃ (w
t%) ≦ 5.

As a hematite substrate, α-Fe ₂ O ₃
In contrast, Al ₂ O ₃ (40 wt% or less), ZrO ₂ (4
0 wt% or less), CeO ₂ (40 wt% or less), ZnO
(30 wt% or less) and TiO ₂ (20 wt% or less) added composition can be used (Japanese Patent Publication No. 1-2222).
0). In addition, with respect to α-Fe ₂ O ₃ , Cr, Mo, T
One containing 0.1 wt% or more and 5 wt% or less of oxides of a and W (JP-A-6-12611), or α-Fe
To ₂ O _3, the Cr ₂ O ₃ or the like can also be used those obtained by adding 20 mol% or less.

The composition of the soft magnetic film obtained by performing dc sputtering without introducing oxygen gas into the sputtering chamber, that is, without supplying oxygen gas near the substrate, is 8.0 wt% Si, 3.
It is 0 wt% Al, the remaining Fe and trace elements.

In the present invention, dc sputtering is performed while periodically supplying oxygen gas to the vicinity of the substrate, and the A layer of the magnetic film formed without supplying oxygen gas and the film with oxygen gas supplied. The soft magnetic film is formed by alternately stacking the B layers of the magnetic film. The thickness of the A layer of the magnetic film is 20 nm to 15
0 nm, the thickness of the B layer is 0.8 nm or more, preferably 2.
It can be 5 nm to 5 nm.

The standard film forming conditions of the present invention are as follows: Ar gas supply amount: 100 sccm O ₂ gas supply amount: 10 sccm O ₂ gas supply period: 30 seconds (A layer thickness 50 nm) O ₂ Gas supply time: 2 seconds (B layer thickness 3 nm) Substrate temperature: Room temperature Film formation rate: 100 nm / min dc bias: -30V rf bias: 0V

A detailed description will be given below.

In the present invention, the A layer of the magnetic film formed without oxygen gas supply and the B layer of the magnetic film formed under oxygen gas supply are formed to have thicknesses of 50 nm and 3 nm, respectively. The process was repeated to prepare a soft magnetic film having a thickness of 3 μm in which the A layer and the B layer were alternately stacked.

At this time, the Ar gas supply amount is 100 scc
m (standard cubic centimeter: standard state volume cm)
³ ), the supply amount of oxygen gas near the substrate is 10 sccm,
The total gas pressure was 2 mmTorr. Applied to the substrate d
c bias is -10V to -100V, rf bias is 5
The range was W to 20W. The sputtering voltage applied to the target was about -800V. As a comparative example, film formation was also performed under the condition that these biases were not applied.

After forming the soft magnetic film, the substrate is placed in a vacuum heat treatment furnace and 700 ° C. in a vacuum of 5 × 10 ^-6 Torr or less.
Heat treatment was performed for 1 hour. Then, the initial permeability of the magnetic film was measured at a frequency of 2 MHz by the Fayrite yoke method.

FIG. 1 shows that the dc bias applied to the substrate is zero.
V, -10V, -20V, -30V, -40V, -50
6 is a graph showing the relationship between the dc bias and the initial magnetic permeability of the magnetic film when V and −100 V are changed. Dc on the board
When no bias is applied, the initial permeability of the magnetic film is 500.
Although it shows a low value, a dc bias is applied to the substrate.
When 15V to -50V is applied, the initial magnetic permeability is 200.
When the applied voltage is −20 V to −40 V, the initial magnetic permeability is 3000 or more, which is a more favorable soft magnetic property. When a dc bias higher than that is applied,
A decrease in initial permeability is observed. Therefore, in the present invention, the dc bias applied to the substrate is -15V to -50V, preferably -20V to -40V.

FIG. 2 shows that the rf bias applied to the substrate is zero.
When changing to W, 5W, 10W, 15W, 20W,
It shows the relationship between the rf bias and the initial magnetic permeability of the magnetic film. The dc bias at this time is 0V. When the rf bias is applied to the substrate, an increase in initial permeability similar to that of the dc bias is observed. By applying an rf bias of 7 W to 17 W, the initial magnetic permeability shows a good soft magnetic property of 2000 or more, and by applying the rf bias of 9 W to 12 W, the initial magnetic permeability of 3000 or more, a better soft magnetic property is obtained. Shows. Therefore, the application of the rf bias to the substrate is set to 7 W to 17 W, preferably 9 W to 12 W.

The above dc bias and rf bias improve the initial permeability in different ways, so
Either one or both may be applied.

In FIG. 3, the substrate temperature is room temperature (30 ° C.), 10
It shows the relationship between the substrate temperature and the initial magnetic permeability of the magnetic film when changed to 0 ° C, 200 ° C, and 300 ° C. dc
When the temperature of the substrate during sputtering is 350 ° C. or less, the initial magnetic permeability shows a good soft magnetic property of 2000 or more, and when the substrate temperature is 100 ° C. or less, the initial magnetic permeability is 3000 or more, and a more favorable soft magnetic property. Is shown. Therefore, the temperature of the substrate during dc sputtering is 350 ° C. or lower, preferably 100 ° C.
It should be below ° C.

In FIG. 4, the oxygen gas supply amount is 0 sccm, 5
sccm, 10 sccm, 15 sccm, 20 sccm
4 shows the relationship between the oxygen gas supply amount and the initial magnetic permeability of the magnetic film when changed to. In the periodic supply of oxygen gas to the vicinity of the substrate, the initial permeability is 2 when the supply amount of oxygen gas per supply is 4.5 sccm to 14 sccm.
000 or more showing good soft magnetic characteristics, among which 9sc
From cm to 11 sccm, the initial magnetic permeability is 3000 or more. Therefore, the amount of oxygen gas supplied per periodic supply to the vicinity of the substrate should be 4.5 sccm to 14 sccm, preferably 9 sccm to 11 sccm.

In FIG. 5, the oxygen gas supply time is 0 seconds, 1 second,
It shows the relationship between the oxygen gas supply time and the initial magnetic permeability of the magnetic film when changed to 2 seconds, 4 seconds, 6 seconds, and 8 seconds. That is, it shows the relationship between the thickness of the B layer and the initial magnetic permeability when the thickness of the B layer was changed from 0 nm to 13 nm. In the periodic oxygen gas supply to the vicinity of the substrate, the oxygen gas supply time per supply is 0.5 seconds or more,
Shows good soft magnetic properties with initial permeability of 2000 or more,
At 1.5 to 3 seconds, the initial magnetic permeability is 3000 or more. Therefore, the oxygen gas supply time per periodic supply to the substrate is 0.5 seconds or more, preferably 1.5 to 3
Seconds. That is, the preferable thickness of the B layer is 0.8n.
m or more, preferably 2.5 nm to 5 nm.

FIG. 6 shows an oxygen gas supply cycle of 8 seconds and 15 seconds.
It shows the relationship between the oxygen gas supply cycle and the initial magnetic permeability of the magnetic film when changed to seconds, 30 seconds, 60 seconds, and 120 seconds. That is, the thickness of the A layer is 13 nm to 300 nm.
It shows the relationship between the thickness of the A layer and the initial magnetic permeability when it is changed up to. In the periodic supply of oxygen gas near the substrate, the supply cycle is 12 to 90 seconds, and the initial permeability is 2
000 or more, a good soft magnetic property is exhibited, and in 25 to 40 seconds, the initial magnetic permeability is 3000 or more. Therefore, the oxygen gas supply cycle of the periodic supply to the vicinity of the substrate is 12 to 90.
It should be in seconds, preferably 25-40 seconds. That is, the preferable thickness of the layer A is 20 nm to 150 nm, and preferably 42 nm to 67 nm.

FIG. 7 shows the relationship between the oxygen content in the B layer of the magnetic film and the initial magnetic permeability. The initial permeability shows the maximum value when the oxygen content of the B layer is around 15 atom%. When the oxygen content is 5 to 20 atomic%, the initial magnetic permeability is 2000 or more, and the soft magnetic characteristics are good. When the oxygen content is 11 to 17 atomic%, the initial magnetic permeability is 3000 or more, which is the better soft magnetic characteristics. Therefore, the oxygen content in the B layer of the magnetic film is 5 to 2
It is 0 atom%, preferably 11 to 17 atom%.

According to the present invention, the oxygen content in the A layer of the magnetic film is constant at about 3 atom%, but when the oxygen content of the A layer exceeds 5 atom%, the initial magnetic permeability decreases. , The upper limit is 5 atomic% or less.

In the present invention, with respect to the constituent metal elements of the magnetic film, Fe, Si and Al, the proportion of oxides in each element was examined by X-ray photoelectric spectroscopy. FIG. 8 shows the result with respect to the oxygen concentration in the B layer.

In the B layer of the magnetic film, as the oxygen concentration increases,
First, it can be seen that Al is first oxidized, and Si is oxidized after all Al is oxidized. In a magnetic film in which all Si is oxidized, the electric resistance increases sharply.
Therefore, it is considered that the magnetic exchange coupling is also lost when the A layer is electrically insulated by the B layer, and such a magnetic film having the B layer and the A layer does not exhibit soft magnetism. It seems to be. In the present invention, as described above, the best soft magnetic characteristics are exhibited when the oxygen concentration in the B layer is 11 to 17 atomic%.
It can be seen that Al is all oxidized and part of Si is oxidized.

[0039]

As described above, according to the present invention, when a soft magnetic film of an alloy magnetic material consisting of Fe, Si, Al and other trace elements is formed on a non-magnetic oxide substrate by sputtering, Since dc sputtering was performed while periodically supplying oxygen gas, it was possible to obtain a soft magnetic film of a Fe-Si-Al alloy having a high saturation magnetic flux density and a high magnetic permeability.

[Brief description of drawings]

FIG. 1 is a graph showing a relationship between a dc bias applied to a substrate and an initial magnetic permeability of a magnetic film.

FIG. 2 is a graph showing the relationship between the rf bias applied to the substrate and the initial magnetic permeability.

FIG. 3 is a graph showing the relationship between substrate temperature and initial magnetic permeability.

FIG. 4 is a graph showing the relationship between the oxygen gas supply amount and the initial magnetic permeability.

FIG. 5 is a graph showing the relationship between the oxygen gas supply time and the initial magnetic permeability.

FIG. 6 is a graph showing the relationship between the oxygen gas supply cycle and the initial magnetic permeability.

FIG. 7 is a graph showing the relationship between the oxygen content in the B layer of the magnetic film and the initial magnetic permeability.

FIG. 8: Oxygen content and Fe, Si, A in B layer of magnetic film
It is a graph which shows the relationship with the ratio which each oxide in 1 occupies.

Claims (6)

[Claims] 1. Fe, Si, Al on a non-magnetic oxide substrate
In a method of manufacturing a soft magnetic film, which is formed by dc sputtering, a soft magnetic film of an alloy magnetic material composed of other trace elements, dc sputtering is performed while periodically supplying oxygen gas to a nonmagnetic oxide substrate. A method of manufacturing a characteristic soft magnetic film. 2. The manufacturing method according to claim 1, wherein dc sputtering is performed while applying at least one of a dc bias and an rf bias to the nonmagnetic oxide substrate. 3. The method according to claim 2, wherein the dc bias is −15V to −50V. 4. The manufacturing method according to claim 2, wherein the rf bias is 7 W to 17 W. 5. The soft magnetic film layer of the soft magnetic film formed without supplying oxygen gas has an oxygen content of 5 atomic% or less, and the soft magnetic film layer of the soft magnetic film layer formed by introducing oxygen gas. The oxygen content is 5 atomic% or more and 20 atomic% or less,
2, 3 or 4 manufacturing method. 6. The soft magnetic film layer of the soft magnetic film formed without supplying oxygen gas has a thickness of 20 nm to 150 n.
6. The method according to claim 1, wherein the soft magnetic film layer formed by introducing oxygen gas has a thickness of 0.8 nm or more.