JPH07320236A - Magnetic head - Google Patents

Abstract

(57) [Abstract] [Purpose] In a composite magnetic head, the element temperature rises as the sense current increases, so that the energization life of the head is greatly reduced, and at the same time, the thermal noise is increased due to the increase in resistance. An object of the present invention is to provide a long-life, low-noise magnetic head capable of significantly increasing the output by increasing the sense current. According to the present invention, a carbon film, which has a thermal conductivity substantially equal to or higher than that of a metal but has a high insulating property, is used as an insulating layer formed in a composite magnetic head. That is, carbon is sputtered by a sputtering method, an ion beam sputtering method, or the like to form the insulating films 2, 4, 10, 13. As a result, the entire head can be made of a material having a high thermal conductivity, and a structure can be achieved in which heat dissipation is extremely good.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic head suitable for recording / reproducing information signals in a high density magnetic recording device, and more particularly to a magnetic head capable of achieving a long life, low noise and high output.

[0002]

2. Description of the Related Art A conventional composite magnetic head in which a magnetoresistive head dedicated to signal magnetic flux detection and an electromagnetic induction thin film head for signal writing are stacked includes a magnetoresistive head, an electromagnetic induction thin film. The insulating layer used in the head portion is mainly composed of an insulator made of an oxide such as Al ₂ O ₃ or SiO ₂ as described in JP-A-61-2242313. Further, regarding the substrate material used for the above magnetic head, Japanese Patent Laid-Open No. 61-2
As disclosed in Japanese Patent Publication No. 94625, magnetic oxide ceramics such as NiZn ferrite, and
As described in JP-A-082312, ZrO
An oxide ceramics of the non-magnetic, such as ₂ are used. The main reason why the oxide is used as the insulating layer is that these oxides have a high withstand voltage and have excellent insulating properties, so that they can be used even with a considerably thin film thickness. However, since these oxides have low thermal conductivity, the heat dissipation efficiency of the Joule heat generated in the magnetoresistive effect element portion in the magnetoresistive effect head is very poor as compared with metal. That is, in the conventional magnetic head described above, no special consideration was given from the viewpoint of efficiently dissipating the heat generated inside the head.

[0003]

As the density of magnetic recording increases, the recording wavelength and the recording track width tend to decrease, and the reproduction output of the magnetic head tends to decrease accordingly.
As described above, in order for the magnetic recording apparatus to operate normally even if the recording wavelength and the track width are decreased, it is necessary to compensate for the decrease in the reproduction output of the magnetic head due to the decrease in the recording wavelength and the recording track width. That is, it is necessary to prepare a method for increasing the head output by an expected decrease in the reproducing head in advance.

Various methods are conceivable for increasing the reproduction output of the magnetoresistive head. For example, the most reliable method is to increase the sense current value flowing in the magnetoresistive effect element. When the sense current is increased, the output of the magnetoresistive head also increases substantially in proportion. However, on the other hand, the Joule heat generated in the element portion also increases, so that the temperature of the element also largely increases. If the temperature of the device becomes too high, the output will decrease from a certain point. Therefore, it is important to suppress the temperature rise as much as possible even if the sense current value is increased. At the same time, it is the energization life of the magnetoresistive head that becomes a problem due to the temperature rise. The energization life of the magnetoresistive head is mainly determined by the sense current density and the element temperature, but it is very sensitive to temperature, changes exponentially, and greatly decreases as the temperature rises. Therefore, from the viewpoint of energization life, there is almost no point in increasing the current unless the temperature rise due to the increase in the sense current can be suppressed.

In the conventional composite magnetic head in which a magnetoresistive effect type head dedicated to signal magnetic flux detection and an electromagnetic induction type thin film head dedicated to signal writing are laminated, as described above, Al having a low thermal conductivity is used as an insulating layer. ₂ O ₃ film or SiO ₂
An oxide film such as a film is used. Therefore, the heat dissipation efficiency of the Joule heat generated in the magnetoresistive effect element section or the writing coil section, which is narrowed by these insulating layers, is not good. Therefore, when the sense current flowing through the magnetoresistive effect element or the coil current flowing through the write coil is increased, the temperature rise of the magnetoresistive effect element or the temperature rise of the entire head due to the Joule heat generated thereby cannot be suppressed. However, there is a problem that the energization life of the magnetoresistive head is significantly reduced.

An object of the present invention is to provide a long-life and low-noise magnetic head capable of achieving high output due to an increase in current.

[0007]

To solve the above-mentioned problems, Joule heat generated by the sense current and coil current of the magnetic head is efficiently dissipated to raise the temperature of the entire head or at least the temperature of the element part. The rise should be suppressed sufficiently. As this method, it is effective to replace the insulating layer made of an oxide having a low thermal conductivity with one having an extremely good thermal conductivity. In this case, it is important to ensure the insulating property.

According to the present invention, at least one of the insulating layers formed in the thin film magnetic head is formed of a carbon film having a thermal conductivity substantially equal to or higher than that of a metal but having a high insulating property. For example, the insulating layer is formed of a thin film of at least one of the i-carbon film and the diamond-like carbon film by a normal sputtering method, an ion beam sputtering method, or the like.

Further, as one of the modified examples, it is formed by mixing an i-carbon film and a diamond-like carbon film. As a result, the entire magnetic head is made of a material having good thermal conductivity, and the Joule heat can be diffused extremely well in the entire head, or at least in the element portion. Furthermore, carbon can also be used for the substrate forming the magnetic head to enhance the conduction of heat escaping through the substrate.

[0010]

Most of the Joule heat generated by the sense current flowing through the magnetoresistive element and the coil current flowing through the writing coil is dissipated through the insulating layers laminated so as to sandwich the magnetoresistive element or the writing coil. Become. Therefore, the amount of heat radiated through the insulating layer depends on the thermal conductivity K of the insulating layer. Let Q ₁ be the amount of heat transfer that escapes through the insulating layer.
₁ can be expressed as Q ₁ = AK (T ₀ −T ₁ ) / l. (Where A
Is the area of the insulating layer in contact with the heating element, T ₀ is the interface temperature of the insulating layer in contact with the heating element, and T ₁ is the insulating layer temperature at the interface on the opposite side through the thickness l of the insulating layer. ) For example, when the heat generation amount per unit time of the element is Q ₀ , Q ₀ is small, and in comparison with this, when the thermal conductivity K of the insulating layer in contact with the element is large and Q ₁ is larger, that is, Q 1 _{When 0} ≦ Q _1, the element temperature does not rise due to heat generation. However, conversely, if the thermal conductivity K is small and Q ₀ is larger than Q ₁ , that is, if Q ₀ > Q ₁ , then the heat quantity of ΔQ = Q ₀ −Q ₁ will accumulate in the element. The temperature rises and settles to a nearly constant temperature in a steady state after a certain time. Naturally, the magnitude of this steady-state temperature also depends on the magnitude of K of the insulating layer. Since the thermal conductivity K ₁ of an insulating layer made of an oxide film such as an Al ₂ O ₃ film or a SiO ₂ film which has been conventionally used is smaller by one digit to two digits than that of a metal, From the viewpoint of the structure and the constituent materials, it is clear that the heat transfer process in the insulating layer is the rate-determining process of the temperature rise of the element and the temperature rise of the entire head.

On the other hand, the thermal conductivity K ₂ of the i-carbon film or the diamond-like carbon film according to the present invention is equal to or higher than the thermal conductivity of metal, and is therefore one order of magnitude higher than K _1.
It is two or more orders of magnitude larger, that is, K ₂ >> K ₁ . Therefore, the heat quantity Q ₁ ′, Q ₁ ′ = A radiated through the insulating layer composed of the i-carbon film or the diamond-like carbon film
K ₂ (T ₀ −T ₁ ) / l is also the amount of heat dissipated through the insulating layer made of an oxide film such as an Al ₂ O ₃ film or a SiO ₂ film Q ₁ ″, Q ₁ ″ =
AK ₁ (T ₀ −T ₁ ) / l is one or two orders of magnitude larger, and Q
₁ '>> Q ₁ ″. As a result, the amount of heat accumulated in the element ΔQ
Is ΔQ ′ = Q ₀ −Q ₁ ′ << ΔQ ″ = Q ₀ −Q ₁ ″, and
The temperature rise of the device is greatly suppressed by using the insulating layer made of the i-carbon film or the diamond-like carbon film having high thermal conductivity.

[0012]

EXAMPLES The effects of the present invention will be described in detail below with reference to examples.

(Embodiment 1) FIG. 1 is a sectional view of a magnetic head according to an embodiment of the present invention. The magnetic head is formed by first using a carbon target on a substrate 1 made of ceramics such as ZrO ₂ or Al ₂ O ₃ .TiC, using a normal sputtering method, a sputtering method in which CH ₄ gas is mixed, or an ion beam sputtering method. Thus, the carbon film 2 is applied with a thickness of 3 to 10 μm to form the insulating layer 2. Thereafter, a lower magnetic shield layer 3 made of a NiFe alloy or a NiFeN alloy is laminated by sputtering with a thickness of 1 to 3 μm and processed into a predetermined shape by photolithography and dry etching. Further, a carbon film 4 for forming a lower gip is laminated thereon to a thickness of 0.05 to 0.3 μm by the same manufacturing method as above to form an insulating layer 4. Then, a soft bias film 5 made of a NiFeNbCo alloy or the like for applying a bias magnetic field to the magnetoresistive film, an intermediate layer 6 made of a high resistance conductive material such as Ta or Ti, a NiFe alloy or CoNi.
The magnetoresistive effect film 7 made of an Fe alloy is continuously laminated with a film thickness of 5 to 30 nm by a vapor deposition method or a sputtering method, and then processed into a predetermined shape by photolithography and dry etching.

Further, it is generally known that, in a magnetoresistive head, the generation of noise called Barkhausen noise due to the movement and disappearance of the domain wall becomes a problem. For this reason, in this magnetic head as well, the magnetic domain control film 8 for suppressing this is formed on the portion other than the track portion of the magnetoresistive film 7 by, for example, 10 to 50 n by the lift-off method.
It is formed with a thickness of m. At this time, at the same time, the conductor film 9 for flowing a sense current through the magnetoresistive effect film 7 also has a thickness of 300 nm.
To form. The conductor film 9 is formed of a laminated film such as Nb / Au / Nb and has a track width of 3.0 μm in this embodiment. Then, a carbon film is formed as the insulating layer 10 for forming the upper gap by the same manufacturing method as described above.
Laminate to a thickness of 0.3 μm. And finally CoNiF
An upper magnetic shield layer 11 made of an e-alloy or a NiFeN alloy is laminated by a sputtering method in a thickness of 1 to 3 μm and processed into a predetermined shape to complete the formation of the magnetoresistive head 12 as a reproducing portion.

Subsequently, the magnetoresistive head section 12 is formed.
An inductive magnetic head portion dedicated to writing is formed on the top. The lower magnetic pole of the inductive magnetic head can also serve as the upper magnetic shield layer 11 of the magnetoresistive head unit 12.
Therefore, in the formation of the induction type magnetic head portion, first, the insulating layer 13 made of a carbon film which becomes the write gap layer is laminated on the upper magnetic shield layer 11. The carbon film has a thickness of 0.1 to 1 μm. After that, although not shown in FIG. 1, a write coil made of a good conductor such as Cu is produced, and a flattening layer of an insulating layer made of a resist film or the like is further laminated, and then the upper magnetic pole 14 is formed into a predetermined shape. Form. Finally, the insulating layer 15 serving as a protective film is laminated with a carbon film to a thickness of 5 μm or more to form the inductive magnetic head portion 16. With the above, the fabrication of the magnetic head 17 according to the present embodiment is completed.

The magnetic head 17 according to the present embodiment records a signal on the magnetic recording medium by the write magnetic flux generated between the upper magnetic pole 14 and the lower magnetic pole 11 of the induction type magnetic head portion 16, and conversely on the magnetic recording medium. A recording / reproducing operation can be performed by reading the signal magnetic flux leaking from the written signal with the magnetoresistive head section 12.

FIG. 2 is a diagram for explaining the effect of the magnetic head 17 according to this embodiment, in which the results of the energization life test are compared with those of the conventional magnetic head. Comparing with the same current density, it can be seen that the energization life of the magnetic head 17 according to the present embodiment is significantly longer than the energization life of the conventional magnetic head. This is the magnetic head 1 according to the present embodiment.
In No. 7, since a carbon film having an excellent heat conductivity is used as the insulating layer, the dissipation of the Joule heat generated in the magnetoresistive effect element portion becomes extremely good, and the temperature rise of the element is suppressed as shown in FIG. Compared with the conventional magnetic head, the element temperature when the sense current is 40 mA is 200 ° C. or higher in the conventional head, whereas the magnetic head 17 according to the present embodiment is 100 ° C. or lower. in this way,
According to the embodiment of the present invention, the energization life of the magnetic head can be greatly increased. In addition, the fact that the temperature rise of the element is suppressed in this manner means that the increase and the variation of resistance noise due to the rise and the variation of the resistance due to the temperature rise and the variation are also suppressed. Therefore, according to the present invention, there is also an effect that the increase and fluctuation of the thermal noise of the magnetic head can be significantly reduced.

According to the above-mentioned embodiment, almost all the insulating layers are formed of carbon film. However, according to another modification, not all the insulating layers are formed of the carbon film as described above, and at least the lower magnetic shield layer 3 and the upper magnetic shield layer 11 of the magnetoresistive head 12 are sandwiched.
The insulating layer forming the head gap may be formed of a carbon film. Even with such a configuration, there is an effect of significantly increasing the energization life of the magnetic head 17.

(Embodiment 2) The magnetic head according to the present embodiment is the same as the Z in the magnetic head 17 according to the embodiment 1 described above.
The substrate 1 made of ceramics such as rO ₂ or Al ₂ O ₃ .TiC was used in place of carbon having excellent thermal conductivity as the substrate 1. Other structures and constituent materials were the magnetic head described in Example 1. Similar to 17. The recording / reproducing operation is exactly the same.

The effect of the magnetic head according to the present embodiment is almost the same as the effect of the magnetic head 17 according to the above-described first embodiment, but the magnetic head of the present embodiment is more effective in the dissipation of Joule heat. It is possible to suppress the temperature rise of the element, and it can be expected that the device has a longer life and lower noise.

Although some embodiments have been described above, as an application example of the present invention, the insulating layer of a magnetic head which is not a composite head but only one head, for example, a magnetoresistive head is used. May be

[0022]

According to the present invention, the energization life of a composite type magnetic head formed by laminating a magnetoresistive head for signal magnetic flux detection and an electromagnetic induction type thin film head for signal writing is significantly increased. Can be increased. Further, increase and fluctuation of resistance noise during the operation of the magnetic head can be significantly reduced.

[Brief description of drawings]

FIG. 1 is a sectional view of a magnetic head according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an effect of the present invention.

FIG. 3 is an explanatory diagram showing an effect of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Substrate, 2, 4, 10, 13, ... Insulating layer, 3 ... Lower magnetic shield layer, 5 ... Soft bias film, 6 ... Intermediate layer, 7 ... Magnetoresistive effect film, 8 ... Magnetic domain control film, 9 ... Conductor Film, 11 ... Upper magnetic shield layer, 12 ... Magnetoresistive head part, 14 ... Upper magnetic pole, 15 ... Protective film, 16 ... Electromagnetic induction type magnetic head part, 17 ... Magnetic head.

Claims (13)

[Claims] 1. A magnetoresistive head portion for detecting a signal magnetic flux from a magnetic recording medium utilizing a magnetoresistive effect, and an electromagnetic induction type thin film head portion for writing a signal on the magnetic recording medium. Of the insulating layer formed on the magnetoresistive head and the electromagnetic induction thin film head, at least the insulating layer between the upper magnetic shield layer and the lower magnetic shield layer of the magnetoresistive head is A magnetic head formed of a carbon film. 2. A magnetic head comprising a magnetoresistive head for signal magnetic flux detection and an electromagnetic induction thin-film head for signal writing, wherein a sense current value flowing through the magnetoresistive head is 40 mA or less. Within the range, the temperature rise of the magnetic sensing portion of the magnetoresistive head is 10 even when the sense current is applied.
A magnetic head characterized in that an insulating layer is formed at a temperature of 0 ° C. or lower. 3. The magnetic head according to claim 1, wherein the carbon film is formed of an i-carbon film or a diamond-like carbon film. 4. The magnetic head according to claim 1, wherein the carbon film is a carbon film containing H. 5. The magnetic head according to claim 1, wherein all the insulating layers formed on the magnetoresistive head and the electromagnetic induction thin film head are carbon films. 6. The magnetic head according to claim 1, wherein the carbon film is formed by mixing i-carbon and diamond carbon. 7. A composite type head comprising a magnetoresistive head for detecting a signal magnetic flux on a substrate and an electromagnetic induction type head for writing a signal on a medium, wherein the substrate is made of a carbon material. Magnetic head composed of. 8. Among the insulating layers formed on the magnetoresistive head and the electromagnetic induction thin film head, at least an insulating layer between the upper magnetic shield layer and the lower magnetic shield layer of the magnetoresistive head is formed. The magnetic head according to claim 7, wherein the magnetic head is formed of a carbon film. 9. The magnetic head according to claim 7, wherein the carbon film is formed of an i-carbon film or a diamond-like carbon film. 10. The magnetic head according to claim 7, wherein the carbon film is a carbon film containing H. 11. A magnetoresistive head for detecting a signal magnetic flux from a magnetic recording medium by utilizing the magnetoresistive effect,
A magnetic head, wherein at least an insulating layer between an upper magnetic shield layer and a lower magnetic shield layer of a magnetoresistive head is formed of a carbon film. 12. The magnetic head according to claim 11, wherein the carbon film is formed of an i-carbon film or a diamond-like carbon film. 13. The head according to claim 11, wherein the substrate of the magnetoresistive head is made of a carbon material.