JPH03148806A - High heat-resistant magnetic thin film and magnetic head using the same - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

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 more particularly to a magnetic thin film with high thermal stability suitable for magnetic heads used in magnetic disk devices, VTRs, etc., and core materials of magnetic heads.

[Conventional technology]

With the increasing density of magnetic recording, MIG (Meta 11 nG
ap) Head has been getting a lot of attention lately. 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 as disclosed in JP-A-62-210607 (Fe, Co,
Magnetic alloys containing nitrogen such as Ni)MN are known. Here, M is Zr, Nb, Ti, or Mo. It is a metal selected from the group consisting of Ta, Hf, Cr, and W.

[Problem to be solved by the invention]

When Co-based amorphous alloys, sendust alloys, (Fe, Go, Ni) MN alloys, etc., as described in the above-mentioned prior art are used, magnetic films exhibiting characteristics suitable for use in magnetic heads can be formed. The maximum saturation magnetic flux density is reported to be 1.4 to 1.5 T, and the heat resistance temperature is reported to be 600 to 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 magnetic thin film that has a saturation magnetic flux density equal to or higher than that of the prior art and is highly heat resistant, and a magnetic head for high-density magnetic recording using the same.

[Means to solve the problem]

The present inventors have revealed that CoBM-based and FeBM-based alloy thin films are magnetic thin films that have high thermal stability and also have a high saturation magnetic flux density. Also. By using the magnetic thin film of the present invention in at least a portion of the magnetic circuit of a magnetic head, a magnetic head having excellent recording and reproducing characteristics can be obtained. r Effect] When a CoBM-based or FeBM-based alloy thin film is heat-treated at high temperatures, fine crystals such as carbides and nitrides will precipitate if boride or C or N is added as M in the film. Since the precipitation of microcrystals inhibits the crystal growth of the magnetic material, the thermal stability of the film is improved. Also. Since B is effective in improving heat resistance when added in a small amount, the magnetic thin film exhibits a high saturation magnetic flux density, and has a high permeability. By using the magnetic head in the section, a magnetic head having excellent recording and reproducing characteristics can be obtained.

【Example】

An embodiment of the present invention will be described below with reference to the drawings. As a result of experiments, there is no particularly large difference in the effect of the additive element M between CoBM-based and FeBM-based alloy thin films, so the following examples will mainly be explained using CoBM-based alloy thin films as an example. [Example 1] An ion beam sputtering device was used to produce a magnetic thin film. Sputtering was performed under the following conditions. Ion gas ArAr gas pressure 2.5XIO”Pa Ion gun acceleration voltage 1000V Ion gun ion current
120mA target-board distance 127m
In this example, a film was fabricated using a composite target in which Ta chips B and M were attached on a Co target. For the substrate, Corning's 7059 glass and Photoceram were used. Here, the characteristics of the film subjected to heat treatment at a temperature of 700° C. were evaluated using a photoceram. ll film thickness is approximately 0.5μm
And so. FIG. 1 shows the results of heat treatment in the range of 300 to 700 DEG C. to examine the thermal stability of a Co□B3Ta film and changes in soft magnetic properties. The heat treatment conditions were to maintain each of the above temperatures for 1 hour in an argon gas atmosphere. Further, the heat treatment was performed in a DC magnetic field of 1 kOe. The magnetic film of this example exhibits excellent soft magnetic properties at a heat treatment temperature of 500°C or higher, and even at a heat treatment temperature of 650°C, the film has a coercive force of about 10e and a relative magnetic permeability of 1000 or higher at 5 MHz. The value was shown. The saturation magnetic flux density at this time was 1.5 to 1.55T. Next, in order to investigate the effect of B concentration on the allowable temperature limit of the film, films were produced by changing the number of B chips attached to the co target. FIG. 2 shows the results of investigating the relationship between coercive force and B concentration of a film heat-treated at 650°C. The Ta concentration is 6at.%, which is almost the same as the sample shown in FIG. B
The coercive force of the CoTa film without addition of is about 140
On the other hand, in the CoBTa film, the coercive force showed a low value of about 30a or less when the B concentration ranged from 0.5at.% to 5at.%. In this example. Although Ta was used as the additive element M, V, Ti. Among elements such as Zr, Hf, Nb, Cr, Mo, and W, addition of Hf, Zr, and Ta has a high heat resistance temperature and also has excellent soft magnetic properties at high temperatures. It has become clear that it is particularly effective as an additive element for highly heat-resistant magnetic films. The reason why the CoBM-based alloy thin film according to the present invention has such high thermal stability is considered to be that microcrystals such as boride are precipitated in the magnetic film by high-temperature heat treatment, and this suppresses crystal grain growth. Therefore, we used high-resolution EPMA to
As a result of analyzing films (Go, B, Ta,) heat-treated at 0°C, it was found that TaB, TaB,
was detected. Furthermore, since diffraction lines that appear to be TaB can be seen in the diffraction pattern obtained using a transmission electron microscope, it is thought that the precipitation of such microcrystals is related to the thermal stability of the film. [Example 2] Next, we will examine the influence of the C concentration on the allowable temperature limit of the film when C, which is thought to have the effect of precipitating microcrystals similarly to B, is added as an additive element M in addition to Ta. as C,
By attaching Ta chips and changing the number of C chips, the influence of C concentration on the film's heat resistance temperature was investigated. FIG. 3 shows the results of investigating the relationship between magnetostriction and C concentration of a film heat-treated at 550°C. The sample used in this example has a B concentration of approximately 3 at.% and a Ta concentration of approximately 6 at.%. C
The magnetostriction of the Co B Ta film without addition of C is positive, and as the amount of C added increases, the magnetostriction of the film changes to negative bias, and after showing the maximum value of negative magnetostriction at a C concentration of about 3 at%, the magnetostriction decreases. It showed a tendency to shift to the positive side. This behavior of magnetostriction as the amount of C added increases,
observed for the first time. Here, the addition of B has the effect of making the magnetostriction of the film positive, so using a film with a C concentration of approximately 3at%, which shows the maximum negative magnetostriction value in Figure 3, the allowable addition amount of B is determined. Examined. FIG. 4 shows the results of investigating the relationship between coercive force and B concentration of a film heat-treated at 650°C. While the coercive force of the CoCTa film without B added is as large as about 100e, the B concentration of the CoBCTa film is about 3
It showed a low value of 0e or less. From the results of this example and example 1, it has become clear that the allowable addition amount of B in the CoBM-based alloy thin film is in the range of about 0.5 to 15 at%. Further, in this example, as in Example 1, V, Ti, and Zr. It was confirmed that similar effects can be obtained by adding elements such as Hf, Nb, Cr, Mo, and W. Next, the allowable addition amount of C when added as M was investigated. Figure 5 is 65
These are the results of investigating the relationship between coercive force and C concentration of a film heat-treated at 0°C. The sample used in this example had a B concentration of approximately 3a.
t, %, Ta'a degree is about 6 at, %. The coercive force of the film showed a low value of about 30e or less when the C concentration was about 15at.% or less. From this, it was estimated that the allowable addition amount of C was approximately 15 at.% or less. It has thus become clear that the addition of C also plays a role in increasing the heat resistance of the film. However, Co CT without B addition
In the a-based alloy thin film, even if the C concentration is increased, a heat resistance temperature of 650°C or higher cannot be obtained, so C alone is not effective in sufficiently increasing heat resistance, and as shown in Figure 1, the addition of B is effective. It was found that it plays an important role in increasing heat resistance. In addition, in a Co CT a-based alloy thin film to which B is not added, in order to increase the heat resistance temperature, it is necessary to increase the amounts of C and Ta added, and the saturation magnetic flux density of the film decreases. On the other hand, since B has the effect of increasing the heat resistance even when added in a relatively small amount, the present invention is effective in obtaining a film having a high saturation magnetic flux density and high heat resistance. Furthermore, the allowable addition amount of elements such as Ta added as M was also investigated. FIG. 6 shows the results of investigating the relationship between coercive force and Ta concentration of - after heat treatment at 650°C. The sample used in this example has a B concentration of approximately 3 at.% and a Ca concentration of approximately 2 at.%. The coercive force of the film without Ta added was as high as about 1508, whereas when 0.5 at.% Ta was added, the coercive force decreased to about 30 a, and the Ta concentration was excellent up to about 15 at.%. It exhibited soft magnetic properties. From this, the allowable addition amount of Ta is approximately 0.5~-↓,
5. :t,%. The allowable amount of such additive elements varies depending on the type of element; for example, for Hf, the allowable amount of addition is approximately 9.5 to 13a.
For V, results of about 0.5 to 20 at,% were obtained. From the above results, the allowable amount of the additive elements M (V, T i , Zr, Hf, Nb, Cr, Mo, W, Ta) in the present invention is from about 0.5 at % to at most 20 at %. % range. Also. As a result of examining the crystal orientation of the films using X-rays for the samples shown in Figs. Broad diffraction peaks were always observed, suggesting that Co microcrystal grains were present in at least a portion of the film. Therefore, the film was observed in the planar and cross-sectional directions using a transmission electron microscope to examine the crystallization state of the film. FIG. 7 shows the results of measuring the grain size of the crystallized portion using a transmission electron microscope for the sample in which the relationship between the coercive force and the B concentration of the film was measured in FIG. 2. The crystal grain size of the CoTa film that does not contain B is approximately 500 nm, and as the B concentration increases, the crystal grain size of the film decreases, and after showing a minimum value at a B concentration of 3 to 4 at%, it shows an increasing trend. Ta. This trend is similar to the change in coercive force, and it appears that the coercive force of the film is influenced by the crystal grain size. B exhibiting such excellent soft magnetic properties
When the concentration is in the range of 0.5 to 5 at%, the crystal grain size is about 300
It was found that it was less than λ. In this study, the thickness of the magnetic film was set to 0.5 μm, but since the crystal grain size of the film is also affected by the thickness of the magnetic film, the B concentration was set to 0.5 at%,
Ta concentration is 6at. % CoBTa films were examined for changes in crystal grain size due to differences in film thickness. FIG. 8 shows the results of investigating the relationship between film thickness and crystal grain size. Here, in order to investigate the critical crystal grain size of a film exhibiting excellent soft magnetic properties, a film with a B concentration of 0.5 at% was used. As a result, there is an almost linear relationship between the film thickness and the crystal grain size, and the film exhibits excellent soft magnetic properties in the lower right region of the figure. There is a difference of 1 og between the grain size d of the crystallized part of the film showing the characteristics and the film thickness t.
It was found that the following relationship holds: tsd50.68Xlog, t-0,05. [Example 3] In Example 1 and Example 2, a single layer film was described. However, the single-layer film has the drawback of poor high-frequency characteristics of specific magnetic flux due to eddy current loss. Therefore, we multilayered the film in order to improve the high-frequency characteristics of relative magnetic permeability and the soft magnetic properties of the film. FIG. 9 shows the cross-sectional structure of the produced multilayer magnetic film. In this embodiment, the multilayer magnetic film 1 has a main magnetic film 11 of Go, B3Ta, a CH alloy thin film with a thickness of 90A, and an intermediate magnetic film 12 of Ni, Fe, - with a thickness of 10. Alloy thin film, and non-magnetic intermediate layer 13 every 10 cycles
It consists of B4C with a film thickness of 50 people. In addition, the multilayer magnetic film 1 has a film thickness of 95 mm Co, B3G,
As the alloy thin film and the intermediate metal thin film 15, the film thickness is 5 mm.
The film and the non-magnetic intermediate layer 13 for each 10-cycle stack are made of B4C with a film thickness of 50. For the substrate 16, 7059 glass manufactured by Corning Inc. and photoceram were used. The number of magnetic films is 50 in each case, and the conjunctival thickness of the multilayer magnetic film is approximately 0.5.
It was set as μm. FIG. 10 shows the results of examining changes in soft magnetic properties due to heat treatment for the multilayer magnetic film of this example. The multilayer magnetic film 1 exhibits excellent soft magnetic properties when the heat treatment temperature is 500°C or higher. After the coercive force showed a minimum value at 600°C, the coercive force rapidly increased at 650°C or higher. On the other hand, the multilayer magnetic film ① exhibits excellent soft magnetic properties when the heat treatment temperature is 600°C or higher, and even at a heat treatment temperature of 700°C, the coercive force of the film is approximately Q, 80a, and the relative permeability at 5MHz is 2000. showed a high value. The saturation magnetic flux density at this time is 1.55 to 1
．． It was 6T. Therefore, in order to investigate the cause of the difference in thermal stability of the film due to the difference in multilayer structure, the cross-sectional structure of the film was observed using a transmission electron microscope. In this example, the lamination period was about 100 people, making it difficult to observe the cross-sectional structure in detail, so a membrane with a lamination period of about 500 people was prepared and the cross-section was observed. As a result, in a multilayer magnetic film (3) whose heat treatment temperature is 600°C or higher, the interface between the main magnetic film 11 and the intermediate magnetic film 12 is unclear, and such interdiffusion between atoms causes a decrease in the coercive force of the film. This is thought to be the cause of the increase. On the other hand, the multilayer magnetic film ① showed a clear multilayer structure even when the heat treatment temperature was 700°C. However, the thickness of the magnetic film 14 was thinner and the thickness of the intermediate metal thin film 15 was thicker than the film not subjected to heat treatment. This is thought to be mainly because B, C, and the like in the magnetic film 14 diffuse into the intermediate metal thin film 15, forming borides and carbides of Ta in this embodiment. [Example 4] Next, CoBM system and Fe having the structure as shown in FIG.
VTR magnetic head using BM multilayer magnetic film (No. 11)
(Figure) was manufactured and the recording and reproducing characteristics of the magnetic head were investigated. V
The magnetic head for TR was manufactured using the process disclosed in Japanese Patent Application Laid-Open No. 62-60113. The Co□B3C multilayer magnetic film used in this example has a thickness of 95A as the magnetic film 14.
A Ta film with a thickness of 5 mm was used as the magnetic thin film and the intermediate metal thin film 15, and a B4C film with a thickness of 50 mm was used as the non-magnetic intermediate layer 13 for every 10 cycles, and the FeBM multilayer magnetic film was used as the magnetic film 14. A Fe, B, C magnetic thin film with a thickness of 95 mm, a Ta film with a thickness of 5 mm as the intermediate metal thin film 15, and a 50 mm thick Ta film as the non-magnetic intermediate layer 13 for every 10 cycles of lamination.
Human B4C was used. Each magnetic film was laminated 200 times, and the film thickness was about 2 μm. M n −Z n on the substrate
Ferrite is used, and the glass for filling has a softening temperature of 45
Head block bonding was performed at a temperature of 600°C using PB glass of 0 to 500°C. The recording and reproducing characteristics of the magnetic head of the present invention have a coercive force of 14,000
The measurement was made using the metal tape of e. The results are shown in Table 1, and for reference, the saturation magnetic flux density is approximately 2. OT Fe-3at%C-2at%Ta
Results for a magnetic head using a /NiFe multilayer magnetic film are also shown. As shown in Table 1, the reproduction output of the magnetic head using the multilayer magnetic film according to the present invention is higher than that of the magnetic head using the F e CT a / N i Fe multilayer magnetic film, which is a typical high saturation magnetic flux density material. (Glass adhesion temperature 0°C), FeBM magnetic film is almost the same Table 1 1 Present invention 1 Conventional example
11 1 (CoBC/Ta) l (Fe
BC/Ta) l (FeCTa/NiFe)
The CoBM-based magnetic film of the 1st grade showed a slightly lower value. However, when comparing the reproduction output of magnetic heads with glass bonded at the same temperature of 600C, it is found that
The magnetic head using the FeC-based magnetic film had a reproduction output about 5 to 6 times higher than that of the magnetic head using the FeC-based magnetic film. This is because in the conventional FeC-based magnetic film, the soft magnetic properties of the multilayer magnetic film deteriorate during the glass bonding process using high-melting-point PB glass, whereas in the multilayer magnetic film according to the present invention, the soft magnetic properties are degraded as shown in FIG. As shown, there is no deterioration of the membrane,
Rather, since the soft magnetic properties are improved, this is considered to be due to the difference in the soft magnetic properties of the a-type film. "Effects of the Invention" As explained above, the CoBM-based and FeBM-based alloy thin films have a high saturation magnetic flux density, and also exhibit excellent soft magnetic properties and high thermal stability. By using the alloy thin film in at least a portion of the magnetic circuit of a magnetic head, a magnetic head with excellent recording and reproducing characteristics can be obtained.

[Brief explanation of the drawing]

FIGS. 1 to 6 and 10 show C o according to the present invention.
B A graph showing the influence of additive elements and heat treatment temperature on the soft magnetic properties of a M-if4 alloy thin film. FIG. 7 is a graph showing the relationship between B concentration and crystal grain size of a CoBM alloy thin film according to the present invention. , FIG. 8 shows C o B according to the present invention.
A graph showing the relationship between the film thickness of an M-based alloy thin film and the crystal grain size of a film exhibiting excellent soft magnetic properties. Figure 9 is a cross-sectional view showing the structure of a multilayer magnetic film. Figure N 11 Invention 0 Multilayer FIG. 2 is a perspective view showing the structure of a V'rR magnetic head using a magnetic film. Explanation of symbols 11, main magnetic film 12, intermediate magnetic film 13, non-magnetic intermediate layer 14, magnetic film 15, intermediate layer wing thin film 16, substrate 81, ferrite 82, multilayer magnetic film 83, Pb-based glass 84, vol. Line window 90, magnetic head for VTR 1 Fig.
tLt, vomit 仝 1O ( 5 8 JJ tLty-t Fig. 5 8 dimensions ) ; δ 1gu->1 Elephant II / TIL - AF (跋ㅅノ次) Fig. a44 (at7c> too11/1 -= Ll/114-t
(ttoi) i mouse S, force Hc (θe) yotlL station i base note (5MHz)
Heir 1,. 42-2, ζ1-

Claims (7)

[Claims] 1. In the CoBM-based or FeBM-based alloy thin film, M is Ti, V, Zr, Hf, Nb, Ta, Cr, M
Contains at least one or more elements selected from o, W,
A highly heat-resistant magnetic thin film characterized in that at least a portion of the film is crystallized. 2. In the CoBM-based or FeBM-based alloy thin film, M is Ti, V, Zr, Hf, Nb, Ta, Cr, M
o, at least one element selected from W, and C, N
1. A highly heat-resistant magnetic thin film, characterized in that at least a portion of the film is crystallized. 3. In the magnetic thin film according to claim 1 or 2, the B concentration in the magnetic film is from 0.5 at% to 15 at%.
A highly heat-resistant magnetic thin film characterized by being in the range of t%. 4. In the magnetic thin film according to any one of claims 1 to 3, M is Ti, Nb, or Zr.
, Hf, V, Ta, Cr, Mo, and W, the concentration of at least one element selected from 0.5 at% to 20 at%.
A highly heat-resistant magnetic thin film characterized by a temperature within the range of %. 5. A highly heat-resistant magnetic thin film according to claim 2 or 3, wherein the concentration of one or more elements selected from C and N as M is 15 at % or less. 6. In the magnetic thin film according to any one of claims 1 to 5, the grain size d of the crystallized portion and the film thickness t
is log_1_0≦0.68×log_1_0t-0.
A highly heat-resistant magnetic thin film characterized by having a relationship of 0.05. 7. A magnetic head characterized in that the highly heat-resistant magnetic thin film according to any one of claims 1 to 6 is used in at least a portion of a magnetic circuit.