JPH0410403A - High heat-resistant multilayered magnetic film and magnetic head using the same - Google Patents

Abstract

PURPOSE:To obtain multilayered magnetic films having high thermal stability and high saturation flux density by using a material which little affects the saturation flux density of a film and hardly separates out gamma-phase for the intermediate layer in a multilayered film consisting of a main magnetic film made from a FeC, FeB, or FeN alloy thin film and the intermediate layer of specified nm thickness. CONSTITUTION:Any multilayered film of FeC, FeB, and FeN with a intermediate layer film thickness of about 2-10nm needs to have a 20% or less of gamma-phase separating out in a film to provide a film excellent in soft magnetic characteristics. Examination of the relation soft magnetic characteristics, saturation flux density, and intermediate layer composition after heat treatment of a multilayered film which uses an alloy thin film of Fe95C2Hf3 for the main magnetic thin film and that of Fe-Hf or Fe-Ta proves that multilayered films made of the intermediate layers with elements of body-centered cubic structure such as Fe-Hf, Fe-Ta which hardly generate gamma-phase loaded to Fe both show soft magnetic characteristics and high saturation flux density when loadings exceed 5at%.

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a magnetic film having high saturation magnetic flux density and high magnetic permeability, and in particular to a multilayer magnetic film with high thermal stability and use in magnetic disk devices, VTRs, etc. using the same as a core material. The present invention relates to a preferred magnetic field. [Prior art] With the increasing density of magnetic recording, MIG (Metal In Gap: M
etal in Gap) head is recent [ ]. However, since the MIG head requires a high-temperature process called glass bonding, a magnetic film with high thermal stability is required. Magnetic films with relatively high thermal stability used in MIG heads include Co-based amorphous alloys, Sendust alloys, and the one disclosed in JP-A-62-210607 (
Magnetic alloys containing nitrogen such as Fe, Co, Ni)MN are known. Here, M is Zr, Nb,
The metal is selected from the group consisting of Ti, Mo, Ta, Hf, and WCr.

[Problem to be solved by the invention]

Co-based amorphous alloys, sendust alloys, and (Fe, Co, Ni) MN as described in the above-mentioned prior art
When alloys are used, the saturation magnetic flux density of a magnetic film exhibiting characteristics suitable for magnetic heads is at most 1.4 to 1.5 T.
, the heat resistance temperature is reported to be 600-700'C. However, in the composition range where the saturation magnetic flux density is maximum, the heat resistance temperature is low, and there are no reports regarding a magnetic film that satisfies both the saturation magnetic flux density and the heat resistance temperature. An object of the present invention is to provide a multilayer magnetic film that has a higher saturation magnetic flux density than the above-mentioned prior art and has high thermal stability, and a magnetic head for high-density magnetic recording using the multilayer magnetic film. [Means for Solving the Problems] The present inventors have achieved high thermal stability and high saturation magnetic flux by using a material for the intermediate layer that has a small effect on the saturation magnetic flux density of the film and is difficult to precipitate the γ phase. It was revealed that a multilayer magnetic film with high density can be obtained. Further, by using the multilayer magnetic film of the present invention in at least a part of the magnetic circuit of a magnetic head, a magnetic head having excellent recording and reproducing characteristics can be obtained. [Function] The present inventors investigated the influence of heat treatment on the magnetic properties of Fe CHf/Ni Fe alloy multilayer films, and found that the cause of the decrease in saturation magnetic flux density during high temperature heat treatment is due to the γ phase entering the film. It was found that this was due to precipitation. It was also revealed that the precipitation of the γ phase was caused by mutual diffusion between the Fe-based main magnetic layer and the intermediate layer. The present invention relates to a multilayer magnetic film having a high saturation magnetic flux density and high heat resistance, using a material in the intermediate layer that has a small influence on the saturation magnetic flux density of the film and does not easily precipitate the γ phase. [Example] An example of the present invention will be described below with reference to the drawings. As a result of experiments, the effect of the intermediate layer according to the present invention is
Since there is almost no difference between main magnetic films such as C-based, Fe3-based, and FeN-based alloys, the following examples will mainly be explained using FeC-based alloy multilayer films. [Example 1] An ion beam sputtering device was used to prepare a magnetic film. Sputtering was performed under the following conditions. Ion gas ・・・・・・・・・・・・ ArAr gas pressure ・・・・・・・・・・・・ 2.5X10””P
a Ion gun accelerating voltage ・・・・・・・・・・・・ 1
00OV ion gun ion current ・・・・・・・・・・・・
・120mA target-to-board distance ・・・・・・
・・・・・・127mrnIn this example, an Fe target with carbon and an I-1f chip attached to improve heat resistance was used.
A CHf composite target is used for the main magnetic film, and FeTa
A multilayer film was formed using an alloy target for the intermediate layer. For comparison, a multilayer film using a NiFe alloy target for the intermediate layer was also formed. The board is Corning 70
59 glass was used. The composition of the fabricated film is such that the main magnetic film is F.
e5sC2I-If3, the intermediate layer film is Fe. T al. and N 180 F ezo (both at%). FIG. 1 shows the change in coercive force of a multilayer magnetic film in which the thickness of one period was constant at 50 nm and the ratio of the film thicknesses of the main magnetic film and the intermediate layer was changed. Each sample was stacked for 10 cycles, and the total film thickness was approximately 5
00 nm. The coercive force of the film is as high as about 700 A/m when the intermediate layer thickness is Onm, that is, a FeCHf single layer film, but when the intermediate layer thickness becomes 2 nm or more, the coercive force decreases rapidly, and at about 5 nm. After showing a minimum value, it showed an increasing trend. As a result of observing cross-sectional transmission electron micrographs, we found that in multilayer films with a thin intermediate layer thickness of 2 nm or less, the effect of the intermediate layer is insufficient, so the F e CHf film grows epitaxially, and becomes soft due to coarsening of crystal grains. It became clear that the magnetic properties had deteriorated. For this reason, in a FeC multilayer film in which the thickness of one period is 50 nm, it is desirable that the intermediate layer thickness be in the range of about 2 to 10 nm. In addition, as a result of examining the effect of the intermediate layer thickness on FeC-based multilayer films with one period thickness of 30 nm and 1100 nm, it was found that similarly excellent soft magnetic properties were obtained when the intermediate layer thickness was in the range of approximately 2 to 10 nm. , the range of the intermediate layer exhibiting excellent soft magnetic properties is 1
It became clear that the period did not have much effect on the film thickness. Figure 1 also shows the value of the saturation magnetic flux density. The saturation magnetic flux density is approximately 2.0 for a Fe CHf single layer film with an intermediate layer thickness of Onm.
It decreases as the intermediate layer thickness increases from 5T, and when the intermediate layer thickness is 10 nm, it becomes approximately 1.95T (FeTa intermediate layer film) and 1
．． 85T (Ni Fe intermediate layer film). The same figure also shows the results of a multilayer film using a non-magnetic 8102 film as the intermediate layer, but when the intermediate layer thickness is 10 nm, it is approximately 1.4T, which is extremely low compared to the above multilayer film. It turns out that an intermediate layer of is advantageous for obtaining a high saturation magnetic flux density material. Figure 2 shows that the intermediate layer thickness is 1 to investigate the thermal stability of the film.
The above multilayer film with a thickness of 0 nm was subjected to heat treatment within the range of 300 to 700°C, and the results of examining changes in coercive force and saturation magnetic flux density in the direction of the easy axis of magnetization are shown. The conditions for the heat treatment are to maintain each of the above temperatures for 1 hour in an argon gas atmosphere. The heat treatment was performed in a DC magnetic field of 80 kA/m (1 kOe). The coercive force of the film showed an excellent property of 160 A/m or less up to 600°C in the multilayer film using any of the intermediate layers, but at 650°C, the coercive force of the multilayer film using the NiFe intermediate layer showed excellent properties.
Furthermore, in the multilayer film using the FeTa intermediate layer, the coercive force increased rapidly at 700°C. The effect of heat treatment on saturation magnetic flux density also differed depending on the intermediate layer material. In a multilayer film consisting of an FeTa intermediate layer, 7
Although the saturation magnetic flux density hardly changes even after heat treatment at 00°C, in a multilayer film using a NiFe intermediate layer,
At 600°C, the saturation magnetic flux density decreases to 1.6T and 700°C.
The temperature decreased to 0.5T at ℃. In order to investigate the cause of this change in saturation magnetic flux density due to heat treatment, the crystal orientation of the film was investigated using X-ray diffraction. As a result, only the (110) diffraction peak due to α-Fe was observed in the multilayer film consisting of the FeTa intermediate layer, whereas the multilayer film with the NiFe intermediate layer had a decreased saturation magnetic flux density. Then, it is caused by α-Fe (110
) In addition to the diffraction peak, a (111) diffraction peak due to γ-Fe was also observed, and the precipitation of γ-Fe was considered to be the cause of the decrease in the saturation magnetic flux density. FIG. 3 shows the results of investigating the relationship between the proportion of γ phase in the film and the amount of decrease in saturation magnetic flux density for various multilayer films heat-treated at 600°C. Here, the ratio of the γ phase is determined by assuming that the (110) diffraction intensity of a-Fe in the X-ray diffraction pattern is I (α) and the (111) diffraction intensity of y-Fe is I (y), as shown in the figure. , calculated from the following formula % formula % (). Within the scope of this example, the diffraction peaks were only those corresponding to the α and γ phases, and the others were not illuminated. There is a correlation between the ratio of γ phase in the film and the amount of decrease in saturation magnetic flux density, and the higher the ratio of γ phase, the greater the amount of decrease in saturation magnetic flux density. From this, it became clear that the cause of the decrease in saturation magnetic flux density due to heat treatment was the precipitation of γ phase into the film. Further, it was found from analysis in the film depth direction by AES (Auger electron spectroscopy) that such precipitation of the γ phase is caused by mutual diffusion between the FeC-based main magnetic film and the intermediate layer. Next, various multilayer films were fabricated and the influence of γ phase precipitation on the soft magnetic properties of the films was investigated. Figure 4 shows the results of heat-treating various multilayer films with different main magnetic film materials and intermediate layer materials at 600°C, and investigating the relationship between the proportion of γ phase precipitated in the film and the coercive force in the direction of the axis of easy magnetization. . Here, the ratio of the γ phase is determined by assuming that the sum of the main diffraction peak intensities due to the α phase and the precipitated phases other than the γ phase (for example, the sum of the diffraction peak intensities corresponding to the various carbides produced) is (0), and This I(0) was added to the denominator of the formula, and it was calculated from the following formula. In the figure, O mark is FeC-based multilayer film, 0 mark is FeC-based multilayer film, and 0 mark is FeC-based multilayer film.
The B-based multi-layer film mark is the result for the FeN-based multi-layer film. From the same figure, any multilayer film of FeC, FeB, or FeN system exhibits excellent soft magnetic properties of 160 A/m or less if the ratio of γ phase precipitated in the film is about 20% or less, and γ
When the phase ratio exceeded about 20%, the coercive force showed a tendency to increase rapidly. From this, it has become clear that in order to obtain a film with excellent soft magnetic properties, the ratio of the γ phase precipitated in the film needs to be 20% or less. Although it is clear from FIG. 1 that the soft magnetic properties of the multilayer film are affected by the thickness of the intermediate layer, it is also thought to vary depending on the composition of the intermediate layer. Therefore, we investigated the influence of the intermediate layer material composition on the soft magnetic properties. Table 1 shows Fe9SC2Hf-1 in the main magnetic film and Fe in the intermediate layer.
-) 1f, the results of investigating the relationship between soft magnetic properties, saturation magnetic flux density, and intermediate layer composition after heat-treating multilayer films using Fe-Ta, Fe-Ni, and Fe-Ru alloy thin films at 600'C. be. The film thicknesses are 40 nm and 10 nm, respectively, and the total film thickness is approximately 500 nm. In the above Table 1, in the coercive force He, O indicates 100 A/m or less, ○ indicates 160 A/m or less, and X indicates 160 A/m or more, and in the saturation magnetic flux density Bs, ◎ indicates 1.8 T or more, and O indicates 1.6 T. In the above, X indicates 1.6T or less. From Table 1, in the intermediate layer where the amount of Fe added is 2 at% or less, the coercive force Hc shows a high value of 160 A/m or more, whereas when the amount of Fe added exceeds 5 at%, excellent soft magnetic The characteristics were shown. As a result of observing cross-sectional transmission electron micrographs, it was found that in multilayer films using an intermediate layer with an additive amount of 2 at% or less, the intermediate layer was unclear and crystal grain growth occurred due to epitaxial growth, whereas the additive amount is 5at%
In a multilayer film using an intermediate layer exceeding 100%, the effect of multilayering due to the intermediate layer was confirmed. Furthermore, as a result of experiments with other elements, Fe-I (f
, a multilayer film consisting of an intermediate layer in which Fe is doped with a body-centered cubic structure (BEC) element such as Fe-Ta exhibits excellent soft magnetic properties and high saturation magnetic flux density when the addition amount exceeds 5 at%. Ta. On the other hand, FeNi, Fe-Ru
In a multilayer film consisting of an intermediate layer in which Fe is doped with elements having a face-centered cubic structure (FEC) or a hexagonal structure (HCP) that easily generates the γ phase, the above-mentioned body-centered cubic structure (b c c
) is different from a multilayer film consisting of an intermediate layer in which Fe is doped with the element Fe1-.
xMx) When the film thickness is t2 and the amount of addition iM is X, the maximum addition amount needs to satisfy the following relationship. In addition, since the FCC, FeB, and FeN-based multilayer film according to the present invention has Fe as its main component, NiFe alloy and FeAlS
Although the corrosion resistance tends to be slightly inferior compared to the i alloy, Ru is an element that improves corrosion resistance. By adding approximately 0.5 to 3 at % of elements such as Rh and Pt, a multilayer magnetic film was obtained that had a high saturation magnetic flux density, high thermal stability, and exhibited corrosion resistance superior to that of FeAlSi alloys. As a result of the above, it is desirable that the intermediate layer material has a body-centered cubic structure or Fe-rich face-centered cubic structure, which is difficult to generate the γ phase. A highly stable multilayer magnetic film can be obtained. [Example 2] Next, a VTR magnetic head (FIG. 5) using the F e CHf / F e Ta multilayer magnetic film was manufactured, and the recording and reproducing characteristics of the magnetic head were investigated. A magnetic head for a VTR was manufactured using the process disclosed in Japanese Patent Application Laid-Open No. 62-60113. F e CHf / F e Ta used in this example
The multilayer magnetic film has a film thickness of 45 nm as the main magnetic film 10.
9° C2Hf, film, 5 nm thick Fe as intermediate layer 11
,. Ta engineering. The film was laminated 100 times, and the film thickness was approximately 5
It was set as μm. Mn-Zn ferrite was used for the substrate, PB glass having a softening temperature of 450 to 500°C was used for the filling glass, and head block bonding was performed at temperatures of 480°C and 630°C. The recording and reproducing characteristics of the magnetic head of the present invention have a coercive force of 120 kA.
Measurements were made using a metal tape of '/m (15000e). The results are shown in Table 2. Also, for reference, Fe with a saturation magnetic flux density of about 1.9T, 5C2T a3
/N 1 so Fe 20 Results for a magnetic head using a multilayer magnetic film are also shown. As shown in Table 2, when the glass bonding temperature is as low as 480°C, the reproduction output of the magnetic head using the multilayer magnetic film according to the present invention is /Almost equivalent to a magnetic head using a NiFe multilayer magnetic film, but the glass bonding temperature is 630'C.
However, it had the same characteristics as when bonded at a low temperature, and the playback output was about 4 to 5 times that of a conventional head bonded at a high temperature. Table 2 *Saturation magnetic flux density of the film at Ni-glass bonding temperature The reason why the reproduction output decreases in conventional multilayer films with NiFe as an intermediate layer is due to the glass bonding process using high melting point PB glass. However, because the γ phase precipitates in the film and the saturation magnetic flux density of the film decreases, this kind of magnetic head cannot write sufficiently on high coercive force media such as metal tape, and the multilayer magnetic film is This is because the soft magnetic properties of the magnet have deteriorated. In contrast, in the multilayer magnetic film according to the present invention, as shown in FIG. 2, there was no deterioration in the soft magnetic properties and saturation magnetic flux density of the film due to heat treatment, and good recording and reproducing characteristics were obtained. [Effects of the Invention] As explained above, by using a material in the intermediate layer that has a small effect on the saturation magnetic flux density of the film and does not easily precipitate the γ phase, a multilayer magnetic film with high saturation magnetic flux density and high heat resistance can be obtained. was gotten. Further, by using the multilayer magnetic film of the present invention in at least a portion of a magnetic circuit, a magnetic head having excellent recording and reproducing characteristics can be obtained.

[Brief explanation of drawings]

Figure 1 is a measurement diagram showing changes in coercive force and saturation magnetic flux density depending on the intermediate layer thickness of the multilayer magnetic film according to the present invention, and Figure 2 is a measurement diagram showing changes in coercive force and saturation magnetic flux density due to heat treatment of the multilayer magnetic film according to the present invention. Figure 3 is a measurement diagram showing the relationship between the proportion of γ phase precipitated in the film and the amount of decrease in saturation magnetic flux density, and Figure 4 is the relationship between the proportion of γ phase precipitated in the film and coercive force. FIG. 5 is a measurement diagram showing the V using the multilayer magnetic film of the present invention.
FIG. 2 is a perspective view and an enlarged cross-sectional view of a main part showing the structure of a TR magnetic head. Explanation of symbols 10 Main magnetic film 11 Intermediate layer 81 Ferrite 82 Multilayer magnetic film 83 PB glass 84 Winding window 90 VTR magnetic head stem) Main 2k +1 u? , wln (r+ %) Hizuzusho friend pushback degree (0) Takuzu genealogy

Claims (3)

[Claims] 1. In a multilayer film consisting of a main magnetic film made of an FeC-based, FeB-based, or FeN-based alloy thin film, and an intermediate layer with a film thickness of 2 to 10 nm, the intermediate layer may be Fe-Cr, Fe-Hf, or F.
e-Mo, Fe-Nb, Fe-Re, Fe-Si, Fe
-Ta, Fe-Ti, Fe-V, Fe-W, Fe-Zr
Consisting of at least one alloy selected from the group of
A highly heat-resistant multilayer magnetic film characterized in that the concentration of elements added to Fe is 5 at% or more. 2. In a multilayer film consisting of a main magnetic film made of an FeC-based, FeB-based, or FeN-based alloy thin film, and an intermediate layer with a film thickness of 2 to 10 nm, the intermediate layer may be Fe-Co, Fe-Ir, or F.
e-Mn, Fe-Ni, Fe-Os, Fe-Pt, Fe
It is made of at least one alloy selected from the group of -Rh, Fe-Ru, and when the main magnetic film thickness is t_1, the intermediate layer thickness is t_2, and the composition of the intermediate layer is Fe_1_-xMx, the additive element M The concentration of is 5 at% or more, and the maximum amount added is
A highly heat-resistant multilayer magnetic film characterized by satisfying the following relationship: t_2×x/(t_1+t_2)<0.1. 3. A magnetic head characterized in that the multilayer magnetic film according to claim 1 or 2 is used in at least a part of a magnetic circuit.