JP2003208708A - Magnetic head and magnetic storage device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To embody a large-capacity magnetic storage device by making it possible to apply an MR (magnetoresistive) head to a magnetic storage device which frequently gives rise to thermal asperity and for which the use of the MR head is heretofore impossible. <P>SOLUTION: A reproducing head section, which constitutes a magnetic recording and reproducing head 200 of the magnetic storage device comprising a magnetic recording medium and the head 200 which is arranged and set apart a prescribed spacing from this magnetic recording medium and executes magnetic recording and reproducing, is composed of a ferromagnetic tunnel junction magnetoresistive effect film 100 comprising a first ferromagnetic layer 11, a second ferromagnetic layer 14 and a tunnel barrier layer 13 held between the first and second ferromagnetic layers 11 and 14. In addition, this ferromagnetic tunnel junction magnetoresistive effect film 100 is so composed that the resistance value of this film 100 exhibits an approximately specified value below 5×10<SP>-5</SP>Ω cm<SP>2</SP>. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic head and a magnetic storage device, and more particularly to a magnetic head utilizing a magnetoresistive effect by a ferromagnetic tunnel junction and a magnetic storage device using the magnetic head.

[0002]

2. Description of the Related Art With the miniaturization and large capacity of magnetic storage devices, magnetoresistive heads (hereinafter referred to as MR heads) having a large reproduction output have been put into practical use. This MR
For the head, see “IEEE Trans.on M
agn ,. MAG7 (1971) 150 "in" A
Magnetoresity Reado
ut Transducer ”.
The MR effect used here is an anisotropic MR (hereinafter referred to as AMR) effect due to the NiFe alloy film, and an MR head based on this is called an AMR head.

In recent years, a GMR head using a giant magnetoresistive effect (hereinafter referred to as GMR), which can realize an improvement in recording density by drastically increasing the output, has been attracting attention to this AMR head. In this GMR, in particular, the magnetoresistive effect generally called the spin valve effect, in which the change in resistance corresponds to the cosine between the magnetization directions of two adjacent magnetic layers, causes a large change in resistance with a small operating magnetic field. From
It is expected as a next-generation MR head. Regarding the MR head using this spin valve effect, see "IEEE
Trans. on Magn ,. Vol. 30, No.
6 (1994) 3801 "," Design, F
application & Testing of Spin
-Valve Read Heads for Hig
h Density Recording ”.

However, the general drawback of MR heads, including GMR heads, is that the resistance of the reproducing MR element is
This is not only changed by the magnetic flux from the magnetic signal recorded on the magnetic medium, but also easily changed by the temperature change of the element. That is, the MR head is both a magnetic sensor and a temperature sensor. The characteristic of this temperature sensor is that the temperature when the MR head comes into contact with the surface of the medium during high-speed rotation of a magnetic medium using a substrate of high hardness such as glass or aluminum like a magnetic disk device. It rises remarkably and is called thermal asperity, which is a cause of troubles in the magnetic disk device.

Regarding the thermal asperity, "IE
EE Trans. on Magn. , MAG-10
(1974) 899 "in" Magnetores "
as "Active Reading of", and also in "IEEE Trans. on Magn., MA."
G-11 (1975) 1224 "in" Analy
sis of Thermal Noise Spik
e Cancellation "and the like.

As the gap between the magnetic medium and the magnetic head becomes narrower as the magnetic recording density increases, the occurrence of this thermal asperity becomes remarkable. Especially, this gap is 40
In the region of nm or less, the occurrence of thermal asperity becomes remarkable, and it is necessary to specially smooth the surface of the magnetic medium or to provide a complicated compensation circuit. As a result, the manufacturing cost of the magnetic storage device has been increased.

A magnetic tape device or floppy (R) using a flexible magnetic recording medium having a magnetic recording layer formed on a plastic substrate such as polyethylene terephthalate.
In a disk device or the like, even if the magnetic recording medium and the magnetic head are positively brought into contact with each other or a gap is provided by an air bearing, the head is frequently brought into contact because it is a flexible medium. As a result, thermal asperity is remarkably generated, and especially in a floppy (R) disk device, M
There is no case where the R head is adopted.

On the other hand, in recent years, it has been reported that a TMR element exhibiting a magnetoresistance change rate of nearly 20% can be obtained by using a surface oxide film of Al for the tunnel barrier layer.
As an example of reporting such a large magnetoresistance change rate, “April 1996, Journal of Applied Physics, Volume 79, pages 4724-4729 (Journal of Appli
ed Physics, vol.79, 4724-4729, 1996) ".

[0009] The content is that a first ferromagnetic layer made of CoFe is vacuum-deposited on a glass substrate using an evaporation mask,
Subsequently, the mask is replaced and the Al of 1.2 to 2.0 nm thickness is used.
Deposit layers. By exposing the surface of the Al layer to oxygen glow discharge, a tunnel barrier layer made of alumina is formed. Finally, a second ferromagnetic layer made of Co is formed through the tunnel barrier layer so as to overlap with the first ferromagnetic layer to complete the cross-electrode type ferromagnetic tunnel junction element. With this method, the maximum rate of change in magnetic resistance is 18%.
That is a big value.

Another known example is Japanese Patent Laid-Open No. 5-632.
54, JP-A-6-244477 and JP-A-8.
-70148, Japanese Patent Application Laid-Open No. 8-70149, Japanese Patent Application Laid-Open No. 8-316548, and 1997, Journal of Japan Applied Magnetics Society, Volume 21, 493-496. Here, as a method of forming the tunnel barrier layer, A
A method has been proposed in which, after forming the 1-layer, the alumina is grown by exposing it to the atmosphere.

By the way, in order to apply the TMR element to a device such as a magnetic head or a magnetic memory, it is necessary to have a practically small resistance value in order to reduce the influence of thermal noise. This could not be achieved by the conventional tunnel barrier formation method. For example, the resistance value in an area of about 2 μm × 2 μm applied to a magnetic head is 10 k.
It becomes close to Ω and cannot be used at all as a magnetic head that needs to have a resistance value of about 50 Ω.

Further, the magnitude of the signal output voltage is important in the application to the magnetic head corresponding to the high density, but the conventional technique has a problem that a sufficient current density cannot be obtained without deteriorating the element characteristics. It was Further, in the prior art, there are large variations in device characteristics within a wafer and between lots, and it has been difficult to obtain a sufficient manufacturing yield for practical use.

It is considered that these problems are mainly due to the conventional method of forming the tunnel barrier layer. In the method using the oxygen glow discharge, it is difficult to control the thin oxide film thickness, that is, the element resistance because active oxygen in the ion or radical state is used for the oxidation of the conductive layer, and due to the activated impurity gas generated at the same time. There is a problem that the tunnel barrier layer is contaminated and the junction quality deteriorates.

On the other hand, in the method of natural oxidation in the air, dust in the air causes pinholes in the tunnel barrier layer or is polluted with water, carbon oxides, nitrogen oxides, etc., like the oxygen glow discharge. I had many problems. Furthermore, the Journal of Applied Magnetics of Japan (Vol. 22, No. 2-
4, pages 561-564 (1998) report experimental results showing that TMR is temperature independent.

However, in the above report, the tunnel magnetoresistive film including the upper and lower electrodes and the oxidized aluminum layer as the tunnel barrier layer inserted between the upper and lower electrodes is manufactured in the manufacturing process. Although it is shown that the TMR ratio and the resistance R do not change depending on the temperature at the time of annealing, there is no disclosure about the influence on the heat generation at the time of using the magnetic reproducing head.

Further, in the journal of the Japan Society for Applied Magnetics, the resistance value of the obtained tunnel magnetoresistive film is generally two digits higher than the limit resistance value that can be used for the head of the magnetic recording / reproducing apparatus. It shows a resistance value as large as three digits, and therefore, the tunnel magnetoresistive film obtained by the description in the journal of the Japan Society for Applied Magnetics cannot be used as a sensor of a magnetic recording / reproducing apparatus, and There is no suggestion.

In addition, Japanese Unexamined Patent Publication No. 10-208218 or Japanese Unexamined Patent Publication No. 10-93159 can be seen.
In both cases, an inert metal layer that does not form an alloy with either the lower ferromagnetic layer or the non-magnetic layer is formed in the barrier layer in order to reduce the pinholes generated in the tunnel barrier and obtain a larger magnetic change rate. Although the technique of interposing or directly contacting the lower ferromagnetic layer with the substrate immediately below the junction region between the non-magnetic layer and the lower ferromagnetic layer has been disclosed, the temperature-dependent There is no disclosure regarding a non-tunnel magnetoresistive film.

[0018]

Generally, the MR head can be said to be a key device in a mass storage device because the MR head can improve the recording density of the magnetic storage device due to its high output characteristics. However, as described above, since it also has a side surface as a temperature sensor, it is used in a region where the thermal asperity is remarkable, that is, when the gap between the magnetic medium and the head is less than 40 nm or when a flexible magnetic recording medium is used. It was extremely difficult to do.

Therefore, in a magnetic tape device, a floppy (R) disk device or the like which uses a flexible magnetic recording medium having a magnetic recording layer formed on a plastic substrate such as polyethylene terephthalate, the MR head has a remarkable thermal asperity. Since it was difficult or impossible to use, it was difficult to improve the recording density.

Further, even in a magnetic disk device using a high hardness magnetic medium, the gap between the magnetic medium and the head is 40.
In a high-density recording area below nm, it is difficult or impossible to use the MR head unless special measures are taken. Therefore, the object of the present invention is to improve the above-mentioned drawbacks of the prior art, solve the problem of thermal asperity which is an essential drawback of the conventionally used MR head, and solve the conventional MR. This is to realize a large-capacity magnetic storage device by making it possible to apply the MR head to a region where the head could not be used.

[0021]

In order to achieve the above-mentioned object, the present invention basically adopts the technical constitution as described below. That is, the first aspect of the present invention
Of the first ferromagnetic layer, the second ferromagnetic layer and the first ferromagnetic layer.
A magnetic head using a ferromagnetic tunnel junction magnetoresistive film including a tunnel barrier layer sandwiched between a second ferromagnetic layer and the second ferromagnetic layer. Nevertheless, the resistance value of the film is 5 × 10 ⁻⁵ Ωcm ² or less, and the magnetic head is configured to exhibit a substantially constant value. Further, as a second aspect of the present invention, Is a tunnel barrier layer between a first ferromagnetic layer and a second ferromagnetic layer in which the magnetic head produces a magnetoresistive effect in a magnetic storage device for recording and reproducing information by a magnetic recording medium and a magnetic head. Using a ferromagnetic tunnel junction magnetoresistive film with a structure sandwiching
The resistance of the ferromagnetic tunnel junction magnetoresistive film is 5 × 1.
The magnetic storage device is configured to have a resistance of 0 ^-5 Ωcm ² or less.

Further, in the magnetic head according to another aspect of the present invention, particularly when the recording medium is a hard recording medium, the gap between the recording medium and the magnetic head is 4 mm.
The magnetic head is allowed to operate in a state of 0 nm or less.

Further, as another aspect of the present invention, particularly when the recording medium is a hard recording medium, it is driven under the condition that the gap between the recording medium and the magnetic head is 40 nm or less. It is a magnetic storage device that is set to be capable.

[0024]

That is, the ferromagnetic tunnel junction used in the magnetic head of the present invention has a structure in which a tunnel barrier layer made of a thin insulator having a thickness of several nm is sandwiched between two ferromagnetic layers, In addition, the tunnel barrier layer has a low resistance value and has substantially no temperature dependence of the resistance value.

That is, in this structure, when an external magnetic field is applied in the plane of the ferromagnetic layers while a constant current is applied between the ferromagnetic layers, the resistance value changes according to the relative angle of magnetization of both magnetic layers. Since the effect phenomenon appears, it is called a ferromagnetic tunnel junction magnetoresistive effect (TMR). When the magnetization directions are parallel, the resistance value is minimum, and when the magnetization directions are antiparallel, the resistance value is. It will be the maximum. Therefore, by giving a coercive force difference to both magnetic layers, the parallel and anti-parallel states of the magnetization can be realized according to the strength of the magnetic field, so that the magnetic field can be detected by the change of the resistance value. By using the above-mentioned tunnel magnetoresistive film in the above, there is little occurrence of thermal asperity, and therefore, even if the magnetic reproducing head is brought very close to the recording medium, there is no fear of erroneous signal detection. Alternatively, it becomes possible to easily obtain a magnetic storage device using the magnetic reproducing head.

[0026]

EXAMPLES A magnetic head and a magnetic recording according to the present invention will be described below.
The structure of a specific example of the storage device will be described in detail with reference to the drawings.
Reveal That is, FIG. 1 (d) and FIG. 2 (f) show the present invention.
1 shows the configuration of a specific example of such a magnetic head.
In the figure, between the magnetic recording medium and the magnetic recording medium
A head for magnetic recording / reproduction that is arranged via a gap
In a magnetic storage device composed of
The reproducing head portion constituting the first ferromagnetic layer 11 and the second ferromagnetic layer 11
Between the ferromagnetic layer 14 and the first and second ferromagnetic layers 11 and 14
Composed of tunnel barrier layers 13 and 24 sandwiched between
A ferromagnetic tunnel junction magnetoresistive film 100
And the ferromagnetic tunnel junction magnetoresistive film
100 has a resistance value of the film in spite of the temperature change.
5 x 10 ^-FiveΩ cm²It is configured to have the following approximately constant values.
A magnetic recording / reproducing head 200 is shown.

One specific example of the overall structure of the magnetic head according to the present invention is as shown in FIG. 3 or FIG. 4, and the above-mentioned ferromagnetic tunnel junction magnetoresistive effect film 100 is It is used for the portion indicated by 33 in FIG. 3 or 33 in FIG. The temperature coefficient of the ferromagnetic tunnel junction magnetoresistive effect film 100 used in the magnetic head 200 used in the present invention is, for example, ± 0.1.
The temperature coefficient of the ferromagnetic tunnel junction magnetoresistive effect film 100 is preferably within ± 0.04% / ° C, more preferably within 5% / ° C.

Further, the film thickness of the tunnel barrier layer used in the present invention is required to be as thin as possible, generally several nm or less, specifically, 5 nm or less, and more preferably. Is 2 nm or less. The magnetic recording medium (not shown) used by the magnetic head 200 of the present invention is a flexible magnetic recording medium having a magnetic recording layer formed on a substrate such as a synthetic resin such as polyethylene terephthalate. Alternatively, it may be a hard magnetic recording medium composed of a substrate such as glass, aluminum or a hard synthetic resin.

The ferromagnetic tunnel junction magnetoresistive film 100 according to the present invention has low resistance as described above, and at the same time has almost no temperature dependence of the resistance. Even if the magnetic head 200 heats up due to contact with a recording medium or the like during execution of the reproducing operation, the change in the resistance value is small, so that the occurrence of thermal asperity, which has been a problem in the past, is effectively suppressed. Therefore, it is particularly effective when a recording / reproducing operation is performed on a recording medium having flexibility, and when the recording medium is a hard recording medium, while the recording / reproducing operation is being performed, In this case, the gap between the magnetic head unit 200 and the recording medium (not shown) can be set to a smaller gap than before.

More specifically, the gap is, for example, 40 n.
It is possible to set m or less. The magnetic head unit 200 according to the present invention is the same as that shown in FIG.
And as shown in FIG. 2F, the first ferromagnetic layer 11 and the second ferromagnetic layer 11
Ferromagnetic layer 14 and the first and second ferromagnetic layers 11 and 14
The ferromagnetic tunnel junction magnetoresistive effect film 100 is composed of the tunnel barrier layers 13 and 24 sandwiched therebetween, and the ferromagnetic tunnel junction magnetoresistive effect film 1 is provided.
00 senses the magnetic flux from the magnetic signal recorded on the magnetic medium.

The magnetic head unit 200 according to the present invention is
The above-mentioned ferromagnetic tunnel junction magnetoresistive effect film 100 is arranged, for example, in a portion indicated by 33 in FIG. 3, and further, the overall structure of the magnetic reproducing head 200 is shown in FIG. 3 or 4. As described above, the recording head unit 300 for recording a magnetic signal on a magnetic medium (not shown) by the leakage magnetic flux generated from the magnetic gap of the magnetic core 37 sandwiching the exciting coil 38 is also included.

The tunnel barrier layer 13 or 24 constituting a part of the ferromagnetic tunnel junction magnetoresistive film 100 in the present invention is formed by oxygen on at least the surface of the conductive layer made of metal or semimetal. It is desirable that a natural oxide film be present. The natural oxide film in the present invention is preferably formed by oxygen supplied under vacuum.

The tunnel barrier layer 13 in the present invention
Alternatively, the conductive layer made of the metal or metalloid constituting 24 is preferably a layer made of metal or metalloid formed by physical vapor deposition in vacuum. Furthermore,
In the present invention, the tunnel barrier layer 13 or 24 is
A layer formed of a metal or semimetal formed by physical vapor deposition in a vacuum is continuously oxidized in the presence of oxygen in a vacuum without destroying the vacuum state. It is desirable that it is a thing.

On the other hand, in the present invention, in addition to the method of forming a natural oxide film on the layer made of the metal or semimetal,
For example, it may be formed by spontaneously nitriding a layer made of metal or semimetal formed by physical vapor deposition in vacuum with nitrogen. Even in that case, it is desirable to perform the nitriding treatment in vacuum.

Further, in the present invention, the layer made of the metal or semimetal which constitutes the tunnel barrier layer is preferably aluminum (Al). Furthermore, in the present invention, Mg or a lanthanoid can be used as the layer made of the metal or semimetal constituting the tunnel barrier layer, in addition to aluminum (Al).

The shape of the magnetic recording medium in which the magnetic head 200 according to the present invention is used is not particularly limited. For example, the shape of the recording medium may be a disk shape. May be tape-shaped. Here, an example of the overall configuration of the magnetic head 200 according to the present invention will be described in more detail with reference to FIG. 3 or FIG.

That is, in the magnetic head 200, two sheets of the first magnetic shield S1 and the second magnetic shield S2, which are sequentially laminated on the ceramic serving as the slider, are opposed to each other. A reproducing head 200 including a reproducing element using the ferromagnetic tunnel junction magnetoresistive film 100 existing between the first and second magnetic shields S1 and S2, and further including the two first magnetic shield films. One of the magnetic shields S1 and the second magnetic shield film S2, for example, the second magnetic shield S2 is also used as one magnetic pole film, for example, the first magnetic pole film P1. On the side opposite to the magnetoresistive effect reproducing element 100, the coil 38 sandwiched by an insulator (not shown) and the other magnetic pole, that is, the second magnetic pole film P2 are provided with respect to the first magnetic pole film P1. Stacking It is, the first and second magnetic pole film P1
And a recording head 300 for recording a magnetic signal on a magnetic medium by a leakage magnetic flux generated from a magnetic gap provided between P2 and P2.

The structure of the magnetic recording layer constituting the recording medium used in the present invention is not particularly limited. For example, the magnetic recording layer is formed by a physical vapor deposition method. It is desirable that it is a magnetic thin film. A magnetic head 200 having a ferromagnetic tunnel junction element 100 having resistance values and signal output voltage characteristics necessary for practical use and improving the manufacturing yield for the purpose of eliminating the conventional defects.
A specific example of the basic configuration of the manufacturing method will be described below.

That is, in the method of manufacturing the ferromagnetic tunnel junction device 100 having the structure in which the tunnel barrier layer 13 is sandwiched between the first ferromagnetic layer 11 and the second ferromagnetic layer 14, the first ferromagnetic layer 11, in the step of continuously forming the tunnel barrier layer 13 and the second ferromagnetic layer 14 in a vacuum, after forming the first ferromagnetic layer 11 and then forming a conductive layer made of a metal or a semiconductor. , A step of introducing oxygen into a vacuum and naturally oxidizing the surface of the conductor layer to form a tunnel barrier layer,
And a step of forming the second ferromagnetic layer 14 thereafter.

Further, in the present invention, the tunnel barrier layer 13 is provided between the first ferromagnetic layer 11 and the second ferromagnetic layer 14.
In the method of manufacturing a ferromagnetic tunnel junction magnetoresistive effect film 100 (TMR film) having a structure sandwiching, a first ferromagnetic layer 11, a tunnel barrier layer 100, and a second ferromagnetic layer 14 are provided.
In a step of continuously forming the first ferromagnetic layer 11 after forming the first ferromagnetic layer 11 by introducing oxygen into the vacuum.
The step of oxidizing the surface of the ferromagnetic layer 11 and the step of forming a tunnel barrier layer by introducing oxygen into a vacuum after forming a conductive layer made of a metal or a semiconductor to spontaneously oxidize the surface of the conductor layer. And a step of forming the second ferromagnetic layer 14 thereafter.

The magnetic head 20 according to the present invention will be described below.
The manufacturing method of 0 will be described in detail. As shown in FIG. 1, after continuously forming an underlayer (10), a first ferromagnetic layer (11), and a conductive layer (12) in a vacuum (FIG. 1A), without breaking the vacuum. Pure oxygen is introduced and the surface of the conductive layer 12 is naturally oxidized to form the tunnel barrier layer 13 (see FIG. 1).
(B)).

FIG. 1B shows the case where the unoxidized portion of the conductive layer remains at the interface with the first ferromagnetic layer (11) even after the conductive layer is oxidized. It is possible to completely oxidize depending on the conditions. After venting oxygen
A second ferromagnetic layer (14) is formed (FIG. 1C). In FIG. 1D, an antiferromagnetic layer (1
5) is formed.

The magnetization of the second ferromagnetic layer is fixed by the exchange coupling magnetic field generated at the interface between the antiferromagnetic layer and the second ferromagnetic layer. Only the first ferromagnetic layer becomes sensitive to the external magnetic field, and the magnetoresistive effect corresponding to the change in the magnetization directions of the first ferromagnetic layer and the second ferromagnetic layer can be obtained. . According to the method described above, the oxide layer can be grown while maintaining a thermal equilibrium state in a clean atmosphere that is not affected by the impurity gas, so that a high-quality tunnel barrier layer can be formed with good controllability. Further, by controlling the oxygen pressure and the substrate temperature, it is possible to obtain an element having a low resistance value and a high current density necessary for device application such as a magnetic head. Further, it is possible to obtain an element having excellent uniformity of element characteristics in the wafer and reproducibility between lots.

When Fe, Co, Ni or an alloy containing them is used for the ferromagnetic layer, by selecting Al having a value smaller than the surface free energy of the ferromagnetic layer as the conductive layer, the first underlayer is formed. Good coverage is possible for the ferromagnetic layer of No. 1. As a result, in the completed device, good characteristics without electric short circuit between ferromagnetic layers due to pinholes can be obtained. Further, since the free energy of formation of Al per oxygen atom is larger than that of Fe, Co, and Ni, alumina, which is the tunnel barrier layer, is thermally stable at the bonding interface.

When a metal belonging to Mg or a lanthanoid is selected for the conductive layer, for the same reason, good coverage with the first ferromagnetic layer (11) as the base and a thermally stable tunnel barrier are obtained. A layer is obtained. FIG. 5 shows an example of the element size dependence of the resistance value of the TMR film obtained by the above method.

In FIG. 5, the track width is assumed to be the case where TMR is applied to a magnetic head, and substantially indicates the dimensions of the TMR film. In this case, for example, the track width of 2 μm is 2 μm.
Dimension of m × 2 μm means 10 μm × 10 μm. The size is 2 μm × 2 μm, and the resistance value is practically several tens Ω. Further, according to this method, it is possible to grow the tunnel barrier oxide layer while maintaining a thermal equilibrium state in a clean atmosphere that is not affected by the impurity gas, so that a high quality tunnel barrier layer can be formed with good controllability. Therefore, by controlling the oxygen pressure and the substrate temperature, it is possible to obtain a TMR film having a thin tunnel barrier layer with lower resistance.

In this method, as shown in FIG. 1, the underlayer (10), the first ferromagnetic layer (11) and the conductive layer (12) are also provided.
Is continuously formed in a vacuum (FIG. 1A), pure nitrogen is introduced without breaking the vacuum, and the surface of the conductive layer 12 is naturally nitrided to form the tunnel barrier layer 13 (FIG. 1B). )) Can also be done. Like the oxide film, the nitride film can serve as a tunnel barrier layer.

Also in this case, as in the case of oxidation, when Fe, Co, Ni or an alloy containing them is used for the ferromagnetic layer, Al having a value smaller than the surface free energy of the ferromagnetic layer is used as the conductive layer. By selecting, it is possible to achieve good coverage with the first ferromagnetic layer as the base.
As a result, in the completed device, good characteristics without electric short circuit between ferromagnetic layers due to pinholes can be obtained.

Further, since the free energy of formation of Al per atom of nitrogen is larger than that of Fe, Co and Ni, aluminum nitride serving as the tunnel barrier layer is thermally stable at the bonding interface. When Mg or a metal belonging to the lanthanoid is selected for the conductive layer, the first base layer is formed for the same reason.
A good thermal barrier property to the ferromagnetic layer (11) and a thermally stable tunnel barrier layer can be obtained.

Next, a second embodiment of the present invention will be described with reference to FIG.
Will be described with reference to. As shown in FIG. 2, after the first ferromagnetic layer (11) is formed, a step of introducing oxygen into the vacuum to form an oxide layer (21) on the surface is added. When the conductive layer (12) is formed, oxygen is diffused from the first ferromagnetic layer (11) to the conductive layer (12), and an oxide layer (23) is also formed on the conductive layer (12) side.

According to this method, since the oxide layer (24) of the conductive layer (12) is formed on both interfaces contacting the ferromagnetic layer, an element having more excellent thermal stability is realized. In order to form a stable oxide layer on the conductive layer (12) side, the free energy of formation per oxygen atom of the conductive layer (12) is larger than that of the element constituting the first ferromagnetic layer (11). is necessary.

When Fe, Co, Ni or an alloy containing them is used for the ferromagnetic layer, A is used as the conductive layer (12).
It is effective to use metals belonging to 1, 1, Mg and lanthanoids. Also in the case of this method, nitrogen can be used instead of oxygen. A head using TMR formed by the above manufacturing method was manufactured for the first time, and its magnetoresistive effect characteristics were examined in detail.

Even with the dimensions of the TMR film of 1 μm × 1 μm, a device of several tens Ω was obtained by adjusting the tunnel barrier film, which was practical. The resistance value of the TMR film formed by this method is 5 × 10 ⁻⁵ Ωcm by controlling the tunnel barrier film.
It was less than ² . Further, surprisingly, it was revealed that the element having the practical resistance value does not change the resistance value even when the temperature is changed.

This is because the conventional TMR film has not been developed at all due to the high resistance value of the TMR film, and no head having a practical resistance value has been reported. It is a new discovery that has never been pointed out. FIG. 6 shows the result of the experiment and the result of the previously reported spin valve head. It was confirmed that the element manufactured this time has a substantially constant resistance value from a low temperature region to a practical region exceeding 100 ° C.

The temperature coefficient of the resistance value was within ± 0.15% / ° C, and was very small within ± 0.04% / ° C. On the other hand, in the conventionally known spin valve head, as shown in FIG. 6, the resistance monotonously increases with temperature, which shows the characteristic that supports the thermal asperity. The temperature coefficient of resistance is as large as + 0.27% / ° C.

In a normal MR head which is not a spin valve, the temperature coefficient of resistance is "IEEE Trans.on.
Magn. , Vol. 32, No. 1 (1996) 3
8 ”, a value of + 0.15% / ° C. is stated.
Further, in the conventional TMR element, the resistance value is larger by 2 to 3 digits, and it cannot be considered to be applied to the magnetic head in the first place. Naturally, the thermal asperity which is a big problem of the MR head cannot be solved. It was

On the other hand, this time, in the head manufactured in the present invention, the electric conduction by the pure tunnel barrier was realized for the first time, thereby realizing the MR head which eliminates the thermal asperity. Next, FIG. 7 and FIG. 8 show the results of comparative experiments for comparing the thermal asperity characteristics of the magnetic reproducing head 200 of the present invention with those of the conventional magnetic head.

That is, FIG. 7A shows the flying height of the magnetic head in the magnetic head manufactured by the conventional technique, for example, 2
The figure shows a part of the reproduced waveform of the resistance value in the spin valve head when the flying height is set to 0 nm. As is clear from the figure, the reproduced waveform shows that the magnetic head When the recording medium is brought into contact with the recording medium, the resistance value is temporarily reduced in the initial stage, but the resistance value is rapidly increased due to the effect of heat generated as a result of the contact, and thereafter the resistance value is gradually decreased.

The protruding corrugated portion shown in the waveform in FIG. 7 (A) shows a state in which a magnetic signal is detected. Therefore, when the temperature of the magnetic head rises due to the magnetic head coming into contact with the recording medium, a malfunction occurs in the detection of the magnetic signal portion, and an information error occurs.

Therefore, in the conventional case, when the magnetic head is used as a flexible recording medium, the magnetic head cannot be brought too close to the recording medium and the information recording density is improved. It was impossible, and there were many false positives. Similarly, even when a hard recording medium is used, for the same reason, it is impossible to perform the recording / reproducing operation with the magnetic head extremely close to the recording medium, and the recording density of information is greatly increased. It was difficult to improve.

On the other hand, in the magnetic head 200 according to the present invention, as shown in FIG. 7B, the resistance value of the ferromagnetic tunnel junction magnetoresistive film 100 shows no temperature dependence. That is, even if the magnetic head 200 contacts the recording medium and the temperature of the magnetic head 200 rises, the resistance value does not change.
As a result, the magnetic head 200 according to the present invention can be used for a flexible recording medium, and when a hard recording medium is used, the magnetic head is extremely close to the recording medium. It is shown that the recording / reproducing operation can be performed by conversely, and conversely, the recording density in the recording medium can be greatly improved.

Therefore, by applying an MR head using a TMR film to a region where the MR head could not be used due to the problem of thermal asperity, it is possible to realize a magnetic storage device having a significantly increased recording capacity. Became. Specifically, a flexible magnetic recording medium having a magnetic recording layer formed on a plastic substrate such as polyethylene terephthalate is used, and a magnetic tape device or a floppy (R) disk device in which the magnetic medium and the magnetic head are frequently in contact with each other.
Alternatively, even in a magnetic disk device that uses a high-hardness magnetic medium, the gap between the magnetic medium and the head is 40 nm.
High-density recording area below

That is, according to the embodiment of the present invention, the gap between the head for magnetic recording / reproducing and the magnetic recording medium is 40 nm.
In the following magnetic head used in a magnetic memory device in a region where thermal asperity frequently occurs in a normal MR head, the magnetic head includes a first ferromagnetic layer and a second ferromagnetic layer that generate a magnetoresistive effect. A reproducing head that senses the magnetic flux from the magnetic signal recorded on the magnetic medium by a reproducing element that uses a ferromagnetic tunnel junction magnetoresistive film having a structure in which a tunnel barrier layer is sandwiched between A magnetic recording / reproducing head comprising a recording head for recording a magnetic signal on a magnetic medium by a leakage magnetic flux generated from a magnetic gap of a magnetic core.

FIG. 8 shows the results of measurement of the change in the gap between the magnetic recording / reproducing head and the magnetic recording medium and the amount of baseline fluctuation using the conventional magnetic head and the magnetic head according to the present invention. . That is, FIG. 8 is a comparative experiment showing the relationship between the flying height of the magnetic reproducing head and the thermal asperity. The recording medium used in the experiment was formed by forming a NiP plating layer on an aluminum substrate, A disk medium in which a recording layer made of CoCrPt and having a coercive force of 2200 Oersted (Oe) was formed and a carbon protective film was formed was used.

The flight height of the medium surface is 30 nm. The gap between the medium and the magnetic head slider was changed by changing the rotation speed of the medium. FIG. 8 shows the relationship between the flying height and the fluctuation amount of the baseline of the head signal (dB display with respect to the noise component in the floating amount where fluctuation does not occur).

In the figure, a magnetic head (TMR) according to the present invention.
Both the conventional magnetic head (MR) and the conventional magnetic head (MR) are shown in the graph. As is clear from FIG. 8, from the place where the flying height of the magnetic head falls below 40 nm, the conventional magnetic head (MR)
It can be seen that the amount of change in the baseline in the field suddenly increases.

The cause is that the conventional magnetic head (M
In R), the frequency of contact with the recording medium sharply increases, and as a result, the output corresponding to the temperature change of the conventional magnetic head (MR) element is detected, which is a phenomenon generally called thermal asperity. is there. On the other hand, in the magnetic head (TMR) according to the present invention, it can be seen that the baseline fluctuation seen in the conventional magnetic head (MR) hardly occurs.

The resistance of the ferromagnetic tunnel junction magnetoresistive film 100 of the magnetic head 200 according to the present invention is 5 × 1.
The magnetic head is characterized in that it is 0 ^-5 Ωcm ² or less. The ferromagnetic tunnel junction magnetoresistive effect film 100 according to the present invention has such a low resistance value that, for example, the tunnel barrier layer 13 of the magnetic head 200 has a physical property in vacuum. It is considered that this is because the layer made of metal or semimetal is formed by the dynamic vapor deposition method, and then oxygen is introduced into the vacuum to naturally oxidize the layer made of the metal or semimetal.

Further, in another aspect of the present invention, there is a magnetic memory reproducing head 400 using the above-mentioned magnetic head 200. That is, as shown in FIGS. 3 and 4, in the magnetic recording / reproducing head 400 that performs information recording / reproducing with the magnetic recording medium and the magnetic recording / reproducing head, the magnetic recording / reproducing head 400 generates the magnetoresistive effect. Signal recorded on the magnetic medium by the reproducing element using the ferromagnetic tunnel junction magnetoresistive film 100 having a structure in which the tunnel barrier layer 13 is sandwiched between the ferromagnetic layer 11 and the second ferromagnetic layer 14 of FIG. And a magnetic recording head 300 for recording a magnetic signal on a magnetic medium by a leakage magnetic flux generated from a magnetic gap of a magnetic core 37 sandwiching an exciting coil 38. The magnetic recording / reproducing head 400 has a ferromagnetic tunnel junction magnetoresistive effect film having a resistance of 5 × 10 ⁻⁵ Ωcm ² or less.

The magnetic recording / reproducing head 40 according to the present invention.
At 0, the temperature coefficient of the ferromagnetic tunnel junction magnetoresistive effect film is preferably within ± 0.15% / ° C., and more preferably, the temperature coefficient of the ferromagnetic tunnel junction magnetoresistive effect film. Is within ± 0.04% / ° C. Further, the film thickness of the tunnel barrier layer used in the magnetic recording / reproducing head 400 according to the present invention is preferably 5 nm or less, and more preferably 2 nm or less.

Further, similarly to the above-mentioned embodiment according to the present invention,
The magnetic recording medium used in the magnetic recording / reproducing head 400 according to the present invention may be a flexible magnetic recording medium having a magnetic recording layer formed on a substrate such as a synthetic resin. The recording medium may be a hard magnetic recording medium having a magnetic recording layer formed on a hard substrate. Therefore, in the magnetic recording / reproducing head 400 according to the present invention, the magnetic recording / reproducing head is allowed to operate in a state where the gap with the recording medium is 40 nm or less.

Further, in the tunnel barrier layer 13 used in the present invention, it is preferable that a natural oxide film formed by oxygen exists on at least the surface of the conductive layer made of metal or semimetal. The natural oxide film is preferably formed by oxygen supplied under vacuum. On the other hand, the conductive layer made of the metal or metalloid that constitutes the tunnel barrier layer is preferably a layer made of metal or metalloid formed by physical vapor deposition in vacuum.

In the same manner as described above, the tunnel barrier layer 13 is a layer formed of a metal or a semimetal formed by physical vapor deposition in a vacuum, and is naturally oxidized in a vacuum in the presence of oxygen. It may be formed by processing,
Alternatively, the tunnel barrier layer of the magnetic reproducing head in the magnetic recording / reproducing head is formed by spontaneously nitriding a layer made of metal or semimetal formed by physical vapor deposition in vacuum with nitrogen. It may be something.

Furthermore, also in the magnetic recording / reproducing head 400 according to the present invention, in the magnetic recording / reproducing head,
On the ceramic serving as a slider, two laminated first and second magnetic shields facing each other, and the ferromagnetic tunnel existing between the two opposing first and second magnetic shields. A read head using a read element using a junction magnetoresistive film, and one of the first and second magnetic shield films described above also serves as the first magnetic pole film, and A coil sandwiched by an insulator and a second magnetic pole film are laminated on the first magnetic pole on the side opposite to the magnetoresistive effect reproducing element, and provided between the first and second magnetic poles. It is preferable that the recording head includes a recording head that records a magnetic signal on the magnetic medium by the leakage magnetic flux generated from the magnetic gap.

Similarly, the magnetic recording layer constituting the recording medium used in the present example according to the present invention is preferably a magnetic thin film formed by a physical vapor deposition method such as a sputtering method. . Hereinafter, specific examples of the present invention will be described in more detail with reference to the drawings. Example 1 Using FIG. 9,
A first embodiment of the present invention will be described. FIG. 9 shows a magnetic recording / reproducing head using a ferromagnetic tunnel junction magnetoresistive film according to the present invention.

A recording / reproducing element 30 is formed on an Al ₂ O ₃ —TiO composite ceramic substrate 29 which constitutes a slider,
It is protected by the alumina protective film 32. Further, electrodes 31 for recording and reproducing are formed. As an example of the structure of this recording / reproducing element, the structure as shown in FIG. 3 can be applied. The element shown in FIG.
It is formed on a 1 ₂ O ₃ —TiO composite ceramic substrate.
A magnetic shield 36 composed of two parallel magnetic films (first
In the magnetic shield S1 and the second magnetic shield S2), the lower magnetic shield S1 was patterned by forming a Co-Ta-Zr-Cr film having a film thickness of 1 μm by a sputtering method.

At the time of forming this Co-Ta-Zr-Cr film, a unidirectional magnetic field was applied in the lateral direction of FIG. Thereafter, an initial heat treatment was performed at 350 ° C. for 1 hour while applying a unidirectional magnetic field of 500 Oe in the easy axis direction of the Co—Ta—Zr—Cr film. The upper magnetic shield S2 was formed by patterning a Ni-Fe film by frame plating. Using the two magnetic shields S1 and S2 as upper and lower electrodes, the pattern 3 of the ferromagnetic tunnel junction magnetoresistive effect film 100 (TMR film) is provided between the two magnetic shields S1 and S2.
3 and magnetic field application films 34 and 35 for controlling the magnetic domains of the free layer were formed.

Ferromagnetic Tunnel Junction Magnetoresistive Film (TM
As the R film), as shown in FIG. 1, the underlying Ta film 10 having a thickness of 30 nm and the Ni-Fe film having a thickness of 10 nm as a free layer having sensitivity to the medium magnetic field are sequentially provided from the lower shield side.
A first ferromagnetic layer 11 made of a film and a conductive layer 12 made of an Al film having a thickness of 2 nm were continuously sputter-deposited. For this film formation, a high frequency magnetron sputtering device equipped with four 4-inch φ targets was used. Sputtering conditions are as follows: background pressure 1x10 ^-7 Torr or less, Ar pressure 3mTo
It was rr and high frequency electric power 200W.

Next, pure oxygen was introduced into the sputtering apparatus,
Oxygen pressure is 1 in the range of 10 mTorr to 200 Torr
After holding for 0 minute, the surface of the Al conductive layer was oxidized to form the tunnel barrier layer 13. After exhausting oxygen to reach the background pressure, a second ferromagnetic layer 14 made of a Co—Fe film having a thickness of 20 nm and an antiferromagnetic film 15 made of a Pt—Mn film having a thickness of 20 nm are sputter-deposited, and TMR is performed. The film was completed.

According to this method, the oxide layer can be grown while maintaining a thermal equilibrium state in a clean atmosphere that is not affected by the impurity gas, so that a high-quality tunnel barrier layer can be formed with good controllability. Further, by controlling the oxygen pressure and the substrate temperature, it is possible to obtain a device having a required low resistance value and high current density. Further, it is possible to obtain an element having excellent uniformity of element characteristics within the wafer and reproducibility between lots. Furthermore, when forming the above-mentioned oxide layer, it is also effective to assist the surface of the wafer with ozone and oxygen ions, which are active species, in an appropriate amount with good controllability. Ultraviolet irradiation, X-ray irradiation, or the like is effective as a method of generating active species. These are evenly distributed in the plane of the wafer to be oxidized, and
It is necessary that the irradiation is performed with good controllability and reproducibility, and that at this time, these do not release the impurity gas from the wall of the vacuum chamber. For that purpose, it must be a highly controlled device system. Conventionally, when direct oxidation was performed by using oxygen glow discharge, it was not possible to form a tunnel barrier layer having low resistance and good quality. It is considered that this method was originally caused by the difficulty in controlling the oxidation, the generation of the impurity gas, and the non-uniform oxidation within the wafer surface. Table 1 shows the TMR film according to the present method and its characteristics,
The TMR film, the AMR film, the GMR (spin valve) film and the characteristics thereof by the conventional method are listed. TMR of this method
The film has a lower resistance than the conventional TMR film, and the temperature dependence of the resistance is extremely small. When the barrier layer thickness is 5 nm or less, a low resistance of 5 × 10 ⁻⁵ Ωcm ² or less can be obtained. More preferably, a low resistance and a high MR ratio can be obtained at 2 nm or less. Further, in the region where a low resistance of less than 1 × 10 ⁻⁸ Ωcm ² is realized, the MR ratio tends to decrease.

[0081]

[Table 1]

After that, an exchange coupling magnetic field is generated between the second ferromagnetic layer 14 and the antiferromagnetic layer 15, and the magnetization of the second ferromagnetic layer 14 is perpendicular to the ABS plane of FIG. In order to fix the heat treatment on the substrate, a unidirectional magnetic field of 3 kOe was applied in a direction perpendicular to the ABS surface, and heat treatment was performed at 230 ° C. for 3 hours. The direction of this magnetic field is orthogonal to the direction of the magnetic field when the lower shield is heat-treated first.

However, the lower shield Co-T
Since the a-Zr-Cr film has been previously heat-treated at 350 ° C., the direction of the easy axis of magnetization does not change even if this heat-treatment is performed, and the anisotropic magnetic field Hk is 8 Oe (8 oersted) and the magnetic shield. As it was, it was large enough. Next, the ferromagnetic tunnel junction magnetoresistive effect film (TMR film) is formed by patterning the ferromagnetic tunnel junction magnetoresistive effect film (TMR film) on both sides of the central region.
Magnetic field applying film 3 for controlling the magnetic domains of the free layer
The edge regions of 4 and 35 were formed.

The magnetic field applying films 34 and 35 are made of Co--Cr--Pt.
It is a permanent magnet film made of. It was important that the permanent magnet film was in contact with the sidewall of the TMR pattern so that the first magnetic layer and the second magnetic layer via the tunnel barrier film were not short-circuited. Further, it is necessary to insert a non-magnetic material between the permanent magnet film and the magnetic shield so that the permanent magnet film is magnetically separated from the magnetic shields above and below it. After that, as described above, a film thickness of 3 μm is formed by the frame plating method as a magnetic shield which is also used as an electrode.
Then, a Ni-Fe film of m was patterned.

Further, with reference to FIG. 3, the subsequent steps of the present invention, that is, the steps of manufacturing the magnetic recording / reproducing apparatus will be described. A 3 μm-thick Ni—Fe film forming the upper shield was formed by frame plating, a magnetic gap was formed of alumina, and then a recording magnetic field generating coil 38 was formed. The coil is insulated by being sandwiched by a photoresist from above and below.

First, a photoresist pattern serving as an insulator on the lower side was formed on the alumina magnetic gap, and this was thermally cured at 250 ° C. for 1 hour. Next, a Cu coil was formed by the frame plating method, and a photoresist pattern serving as an upper insulator was formed. 250 during this heat curing
It heat-processed at 1 degreeC for 1 hour. Further, a Ni—Fe film having a film thickness of 4 μm, which constitutes the recording magnetic pole P2, was formed by frame plating. After forming the upper magnetic pole 37 which is the recording magnetic pole P2, a magnetic field of 1 kOe is applied in the direction of the easy axis of magnetization of the magnetic shield, and 200
It heat-processed at 1 degreeC for 1 hour. Thereby, the magnetic anisotropy of the upper magnetic pole 37 is stabilized.

Next, after forming the wiring patterns 39 and 40 of the electrodes of the reproducing section and the recording section, the entire element was protected by an alumina sputtered film as shown in FIG. After that, again, in order to align the magnetizations of the antiferromagnetic layer of the TMR film and the second ferromagnetic layer in contact with the antiferromagnetic layer, a unidirectional magnetic field of 3 kOe is applied in the direction perpendicular to the ABS plane at 250 ° C. Heat treatment was performed for an hour.

The above elements were cut out from the wafer, processed into a slider shape for a magnetic disk device shown in FIG. 9, incorporated into an arm with a gimbal spring, and evaluated for recording and reproduction. With this head, even with the dimensions of the TMR film of 1 μm × 1 μm, a device of several tens Ω was obtained by adjusting the tunnel barrier film, which was practical. The resistance value of the TMR film by this method is 5 × 10 ⁻⁵ by controlling the tunnel barrier film.
Ωcm ² or less.

As a result of the recording / reproducing evaluation, even if the gap between the magnetic recording medium and the main head was changed and the size was in the region of 40 nm or less, a medium called thermal asperity, which was remarkable in the conventional MR head, was obtained. It has been revealed that the occurrence of an error signal due to the change of the MR element temperature due to the contact between the head and the head is not recognized in this head.

In order to clarify the cause of this, the temperature change of the resistance of the reproducing element of the present head was measured. As a result, it was surprisingly found that this element is an MR element whose resistance value does not change even if the temperature is changed. This is a new finding that has never been pointed out as a TMR head having a practical resistance value. FIG. 6 shows the result of the experiment and the result of the previously reported spin valve element. It was confirmed that the resistance value of the device manufactured this time was almost constant from the liquid helium temperature to a practical range exceeding 100 ° C. The temperature coefficient of resistance was extremely small, about -0.01% / ° C.

On the other hand, in the conventionally known spin valve head, the resistance increases monotonously with temperature as shown in FIG. 6, which shows the characteristic that supports the occurrence of thermal asperity. Temperature coefficient of resistance is + 0.27% / ℃
And big. In a normal MR head that is not a spin valve, the temperature coefficient of the resistance value is "IEEE Trans.
agn. , Vol. 32, No. 1 (1996) 38 "
Values of + 0.15% / ° C.

In the conventional TMR element, the resistance value is 2
It is three orders of magnitude larger than the order of magnitude, and it cannot be considered to be applied to a magnetic head in the first place. Naturally, it was not possible to solve thermal asperity, which is a major problem of MR heads.
On the other hand, in the head manufactured this time, electric conduction by a pure tunnel barrier was realized for the first time,
An MR head that eliminates thermal asperity is realized.

As described above, in the magnetic recording / reproducing head used in the magnetic storage device in which the gap between the magnetic recording / reproducing head and the magnetic recording medium is 40 nm or less, the magnetic recording / reproducing head produces the magnetoresistive effect. From a magnetic signal recorded on a magnetic medium by a reproducing element using a ferromagnetic tunnel junction magnetoresistive film having a structure in which a tunnel barrier layer is sandwiched between a first ferromagnetic layer and a second ferromagnetic layer, A magnetic recording / reproducing head including a reproducing head that senses a magnetic flux and a recording head that records a magnetic signal on a magnetic medium by a leakage magnetic flux generated from a magnetic gap of a magnetic core sandwiching an exciting coil is realized.

The characteristic of this head is that the resistance of the ferromagnetic tunnel junction magnetoresistive film of the magnetic recording / reproducing head is 5 × 10 ^−5.
Ωcm ² or less, and in order to achieve this, the tunnel barrier layer of the magnetic recording / reproducing head is formed in a vacuum after physical vapor deposition in vacuum to form a layer made of metal or semimetal. This is a tunnel barrier layer formed by introducing oxygen into the inside and spontaneously oxidizing the layer made of the metal or metalloid. More preferably, the layer made of the above metal or metalloid is aluminum (Al).
Is to be.

Further, after the tunnel barrier layer of the TMR film is formed by a physical vapor deposition method in a vacuum to form a layer made of a metal or a metalloid, nitrogen is introduced into the vacuum to remove the metal or metalloid from the metal or metalloid. The same effect can be obtained even when the layer is a tunnel barrier layer formed by spontaneously nitriding the layer.
More preferably, the layer made of the metal or semimetal of the TMR film is aluminum (Al).

The magnetic recording medium combined with the present magnetic head is a flexible magnetic recording medium having a magnetic recording layer formed on a substrate such as polyethylene terephthalate.
That is, the gap between the head and the medium is 40 nm or less. The magnetic recording layer is a magnetic recording layer coated with magnetic particles. In addition, the magnetic recording medium has a disk shape. Alternatively, the magnetic recording medium is in the form of a tape.

The magnetic recording layer is a magnetic thin film formed by a physical vapor deposition method such as a sputtering method. The magnetic recording medium is disk-shaped. Alternatively, the magnetic recording medium is in the form of a tape. Further, the magnetic recording medium is
It is a magnetic recording medium in which a magnetic recording layer is formed on a highly hard substrate such as glass or aluminum. The magnetic recording layer of the magnetic recording medium is a magnetic thin film formed by a physical vapor deposition method such as a sputtering method. In addition, the magnetic recording medium has a disk shape.

As a result of the present invention, when the magnetic recording medium combined with the present magnetic head is a flexible magnetic recording medium having a magnetic recording layer formed on a substrate such as polyethylene terephthalate, a high density recording exceeding 500 Mb per square inch. The playhead is realized. Further, when the magnetic recording medium is a magnetic recording medium in which the magnetic recording layer is formed on a substrate having high hardness such as glass or aluminum, 1 square inch is obtained without special measures for coping with thermal asperity. A high-density recording / reproducing head exceeding 10 Gb is realized.

Similar results can be obtained with the structure of the magnetic head of the present invention shown in FIG. That is, in FIG. 4, a TMR element having an individual electrode 41 that is not also used as a shield is formed in the gap between the two opposing magnetic shields 36. In this example, the film thickness of the lower shield layer S1 can be selected, for example, in the range of 0.3 μm to 3 μm, and as the ferromagnetic tunnel junction magnetoresistive film (TMR), The underlying Ta film 10 has a film thickness of 2 nm to 200 nm, and the free layer 11 has a film thickness of 1 n.
It can be appropriately selected within the range of m to 50 nm.

On the other hand, the film thickness of aluminum (Al) used as the tunnel barrier layer 13 is 0.3 nm to 3 nm.
the thickness of the magnetization fixed layer 14 is 1 nm to 5 nm.
The range of 0 nm and the film thickness of the antiferromagnetic film 15 can be arbitrarily selected from the range of 5 nm to 200 nm. Further, the magnetic field applying film 34 made of CoCrPt,
The thickness of 35 is 3 nm to 300 nm, and the magnetic shield S2
Can be arbitrarily selected in the range of 0.3 μm to 4 μm.

The film thickness of the recording magnetic pole 37 can be arbitrarily selected within the range of 0.5 μm to 5 μm. Second Embodiment FIG. 10 shows a magnetic storage device using the magnetic head (FIG. 9) shown in the first embodiment.

In FIG. 10, a magnetic recording / reproducing head 3 of the present invention is attached by a suspension 4 and an arm 5 so as to face a magnetic storage surface of a magnetic medium 2 rotated by a driving motor 1, and a voice coil motor ( VCM) 6. The recording / reproducing operation is performed by a signal from the recording / reproducing channel 7 to the head. The recording / reproducing channel, the VCM for positioning the head, and the drive motor for rotating the medium are linked by the control unit 8.

FIG. 11 shows a magnetic recording device having the above basic structure, in which the magnetic recording medium is a flexible magnetic recording medium having a magnetic recording layer formed on a substrate such as polyethylene terephthalate. The magnetic medium 26 is recorded and reproduced by an assembly 25 incorporating a magnetic head,
It can be taken out for 7.

By using the magnetic head shown in Example 1 (FIG. 9), a storage device having a recording / reproducing system without thermal asperity can be realized in the region where the gap between the medium and the head is 40 nm or less. The magnetic recording layer is a magnetic recording layer coated with magnetic particles. Also,
The magnetic recording layer may be a magnetic thin film formed by a physical vapor deposition method such as a sputtering method.

Example 3 FIG. 10 shows a magnetic memory device using the magnetic head (FIG. 9) shown in Example 1. In FIG. 10, a head 3 of the present invention is attached by a suspension 4 and an arm 5 so as to face a magnetic storage surface of a magnetic medium 2 rotated by a driving motor 1 and is tracked by a voice coil motor (VCM) 6. It

The recording / reproducing operation is performed by a signal from the recording / reproducing channel 7 to the head. The recording / reproducing channel, the VCM for positioning the head, and the drive motor for rotating the medium are linked by the control unit 8. There is. In the magnetic storage device having the above basic configuration, the magnetic recording medium is a magnetic recording medium in which a magnetic recording layer is formed on a highly hard substrate such as glass or aluminum,
FIG. 12 shows an apparatus in which the magnetic recording layer of the magnetic recording medium is a magnetic thin film formed by a physical vapor deposition method such as a sputtering method, and the magnetic recording medium has a disk shape. Show.

The magnetic medium 57 is recorded and reproduced by an assembly 58 incorporating a magnetic head. By using the magnetic head shown in Example 1 (FIG. 9), a storage device having a recording / reproducing system without thermal asperity can be realized in a region where the gap between the medium and the head is 40 nm or less. Example 4 In FIG. 13, the magnetic recording medium is a flexible magnetic recording medium in which a magnetic recording layer is formed on a substrate such as polyethylene terephthalate, the gap between the head and the medium is 40 nm or less, and the magnetic recording medium is tape-shaped. 2 shows the configuration of the magnetic storage device.

The magnetic recording layer is a magnetic recording layer coated with magnetic particles, and the magnetic recording layer is a magnetic thin film formed by a physical vapor deposition method such as a sputtering method. It can be. In this apparatus, the tape-shaped magnetic recording medium 44 supplied from the tape supply reel 45 is a roller 46, a roller 47, a roller 48, a roller 49, a capstan 50 whose rotation speed is controlled by a capstan motor 51, and the like. The traveling of the magnetic head 43 is controlled, the side surface of the rotary drum 42, on which the magnetic head 43 is mounted, is brought into stable contact with the magnetic head 43, and is finally taken up by the take-up reel 52.

The magnetic head applied to this apparatus is shown in FIG.
The shape is shown in. The element 54 for recording / reproducing has the structure described in the first embodiment, is formed on the base body 53 to be a slider, and is protected by the protective film 56 made of alumina.
Further, a terminal 55 for passing a recording current and a reproducing current is formed. The curved portion on the upper surface of FIG. 14 makes smooth contact with the tape-shaped magnetic medium, but a thin air phase is formed due to the relative speed between the head and the medium. With this device, a storage device having a recording / reproducing system without thermal asperity is realized even if the air phase thickness is 40 nm or less.

As another mode of the present invention, as is clear from the above description of each specific example, for example, it is used in a magnetic storage device for recording / reproducing information by a magnetic recording medium and a magnetic recording / reproducing head. In this magnetic recording / reproducing head, a reproducing element using a ferromagnetic tunnel junction magnetoresistive film having a structure in which a tunnel barrier layer is sandwiched between a first ferromagnetic layer and a second ferromagnetic layer is used. When manufacturing a reproducing head that is sensitive to magnetic flux from a magnetic signal recorded on a medium, the tunnel barrier layer of the magnetic recording and reproducing head is made of metal or semimetal by physical vapor deposition in vacuum. A method of manufacturing a magnetic recording / reproducing head configured to introduce oxygen into a vacuum after forming a layer to spontaneously oxidize the layer made of the metal or semimetal, A the magnetic recording and reproducing head used in a magnetic memory device performing information recording and reproduction by the body and the magnetic recording and reproducing head, a first ferromagnetic layer and the second
Of a reproducing head that senses magnetic flux from a magnetic signal recorded on a magnetic medium by a reproducing element using a ferromagnetic tunnel junction magnetoresistive film having a structure in which a tunnel barrier layer is sandwiched between the ferromagnetic layers of In doing so, after forming a tunnel barrier layer of the magnetic recording / reproducing head by a physical vapor deposition method in vacuum, a layer made of metal or semimetal,
This is a method of manufacturing a magnetic recording / reproducing head configured to introduce nitrogen into a vacuum to nitride the layer made of the metal or semimetal.

Further, according to another aspect of the present invention, in manufacturing a magnetic storage device for performing information recording / reproducing with a magnetic recording medium and a magnetic recording / reproducing head, the magnetic recording / reproducing head has a first A magnetic field from a magnetic signal recorded on a magnetic medium is sensed by a reproducing element using a ferromagnetic tunnel junction magnetoresistive film having a structure in which a tunnel barrier layer is sandwiched between a magnetic layer and a second ferromagnetic layer. And a tunnel barrier layer of the magnetic recording and reproducing head, after forming a layer made of metal or semimetal by physical vapor deposition in vacuum,
A method for manufacturing a magnetic memory device configured to introduce oxygen into a vacuum to spontaneously oxidize a layer made of the metal or metalloid, and further, information recording / reproducing by a magnetic recording medium and a magnetic recording / reproducing head. In manufacturing a magnetic memory device for carrying out the above, the magnetic recording / reproducing head has a structure in which a tunnel barrier layer is sandwiched between a first ferromagnetic layer and a second ferromagnetic layer. A reproducing head that senses a magnetic flux from a magnetic signal recorded on a magnetic medium by a reproducing element using a magnetic recording medium is used, and the tunnel barrier layer of the magnetic recording / reproducing head is physically formed in a vacuum. A method of manufacturing a magnetic memory device configured to form a layer made of a metal or a semimetal by a vapor phase growth method, and then introduce nitrogen into a vacuum to nitride the layer made of the metal or the semimetal. A.

[0112]

Since the magnetic head and the magnetic storage device according to the present invention adopt the above-mentioned technical structure, the drawbacks of the prior art are improved, and the resistance is low without any temperature dependence. As a result, the problem of thermal asperity, which is an essential drawback of the conventionally used MR head, can be solved, and the MR can be applied to a region where the conventionally used MR head cannot be used. The effect that the head can be applied can be obtained.

Further, in the present invention, since the problem of thermal asperity can be solved, the medium surface is extremely smoothed in the high density magnetic recording region in which the gap between the magnetic medium and the head is less than 40 nm, and the compensation circuit is used. It is possible to realize a large-capacity magnetic storage device by applying an MR head without taking special measures such as provision of a magnetic head.

[Brief description of drawings]

FIG. 1 is a cross-sectional view illustrating a process procedure in a specific example of a method of manufacturing a magnetic head according to the present invention.

FIG. 2 is a cross-sectional view illustrating a process procedure in another specific example of the method of manufacturing a magnetic head according to the present invention.

FIG. 3 is a perspective view for explaining the outline of the overall configuration of a specific example of the magnetic head according to the present invention.

FIG. 4 is a perspective view for explaining the outline of the entire configuration of another specific example of the magnetic head according to the present invention.

FIG. 5 is a graph showing a relationship between a resistance value and a track width of a magnetic head (TMR) using the ferromagnetic tunnel junction magnetoresistive film 100 according to the present invention.

FIG. 6 is a graph showing the temperature dependence of the resistance value of the magnetic head (TMR) of the present invention and the conventional spin valve head.

FIG. 7A shows an example of a reproduction waveform of a resistance value in a conventional magnetic head (MR), and FIG. 7B shows a resistance in a magnetic head (TMR) of the present invention. It is a graph which shows the example of the reproduction waveform of a value.

FIG. 8 is a graph showing the relationship between the flying height and the baseline variation in the conventional magnetic head (MR) and the magnetic head (TMR) of the present invention.

FIG. 9 is a perspective view showing an example of the configuration of a specific example of the magnetic head according to the present invention.

FIG. 10 shows a magnetic head (TM) according to the present invention.
FIG. 3 is a schematic diagram showing a configuration of a specific example of a magnetic storage device using an (R head).

FIG. 11 shows a magnetic head (TM) according to the present invention.
FIG. 3 is a schematic diagram showing a configuration of a specific example of a magnetic storage device using an (R head).

FIG. 12 shows a magnetic head (TM) according to the present invention.
FIG. 3 is a schematic diagram showing a configuration of a specific example of a magnetic storage device using an (R head).

FIG. 13 shows a magnetic head (TM) according to the present invention.
FIG. 6 is a schematic view of a magnetic storage device for using a narrow recording medium such as a tape using R).

FIG. 14 is a perspective view showing the configuration of a specific example of a magnetic head for using a narrow recording medium such as a tape using TMR according to the present invention.

[Explanation of symbols]

1 ... Drive motor 2 ... Magnetic medium 3 ... Magnetic recording / reproducing head 4 ... Suspension 5 ... Arm 6 ... Voice coil motor (VCM) 7 ... Recording / playback channel 8 ... Control unit 25 ... Assembly incorporating magnetic head 26 ... Magnetic medium 27 ... Device 43 ... Magnetic head 42 ... rotating drum 44 ... Tape-shaped magnetic recording medium 45 ... Tape supply reel 46 ... Laura 47, 48, 49 ... Roller 50 ... Capstan 51 ... Capstan motor 52 ... Take-up reel 53 ... Base 54 ... Recording / reproducing element 55 ... Terminal 56 ... Protective film 57 ... Magnetic medium 58 ... Assembly 29 ... Composite ceramic substrate 30 ... Recording / reproducing element 32 ... Alumina protective film 31 ... Electrode 100 ... Ferromagnetic tunnel junction magnetoresistive film 200 ... Magnetic head 300 ... Recording head 400 ... Magnetic recording / reproducing apparatus 11 ... First ferromagnetic layer 14 ... Second ferromagnetic layer 13, 24 ... Tunnel barrier layer 33, 41 ... Magnetic reproducing head 34, 35 ... Magnetic field applying film 36 ... Magnetic shield electrodes (S1, S2) 37 ... Magnetic core (P2) 38 ... Excitation coil

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hisashi Tsuge             5-7 Shiba 5-1, Minato-ku, Tokyo NEC Corporation             Inside the company F-term (reference) 5D034 BA03 BB08 BB12 CA03                 5D042 NA02 PA05 PA09 QA05                 5E049 BA12 DB06

Claims (21)

[Claims] 1. A ferromagnetic tunnel junction magnetoresistive effect film comprising a first ferromagnetic layer, a second ferromagnetic layer, and a tunnel barrier layer sandwiched between the first and second ferromagnetic layers. A magnetic head using the above, wherein the ferromagnetic tunnel junction magnetoresistive effect film has a resistance value of 5 × 10 ⁻⁵ Ωcm ² or less. 2. The magnetic head according to claim 1, wherein the resistance value of the ferromagnetic tunnel junction magnetoresistive film exhibits a substantially constant value of 5 × 10 ⁻⁵ Ωcm ² or less. 3. The magnetic head according to claim 1 or 2, wherein the temperature coefficient of the ferromagnetic tunnel junction magnetoresistive effect film is within ± 0.04% / ° C. 4. The magnetic head according to claim 1, wherein the tunnel barrier layer has a thickness of 3 nm or less. 5. The magnetic head according to claim 1, wherein the tunnel barrier layer has a thickness of 2 nm or less. 6. The tunnel barrier layer includes a natural oxide film formed of oxygen on at least the surface of a conductive layer made of metal or semimetal.
6. The magnetic head according to any one of 1 to 5. 7. The layer made of the metal or semimetal that constitutes the tunnel barrier layer is aluminum (Al),
7. The magnetic head according to claim 1, wherein the magnetic head is one selected from Mg and lanthanoids. 8. In the magnetic head, two opposing first magnetic shields and second magnetic shields, which are laminated on a ceramic serving as a slider, and two opposing first and second magnetic shields are provided. A reproducing head using a reproducing element using the ferromagnetic tunnel junction magnetoresistive film existing between two magnetic shields, a first magnetic pole film, a coil sandwiched by an insulator, and a second magnetic pole film. 8. A recording head for recording a magnetic signal on a magnetic medium by using a leakage magnetic flux generated from a magnetic gap provided between the first and second magnetic poles. The magnetic head described in 1. 9. A magnetic storage device for recording / reproducing information by a magnetic recording medium and a magnetic head, wherein the magnetic head has a first ferromagnetic layer and a second ferromagnetic layer for generating a magnetoresistive effect.
Of a ferromagnetic tunnel junction magnetoresistive film having a sandwich structure in which a tunnel barrier layer between the ferromagnetic layers, the resistance of 5 × 10 of the ferromagnetic tunnel junction magnetoresistive film ^-5 [Omega] cm ²
A magnetic storage device characterized in that: 10. The magnetic memory device according to claim 9, wherein the resistance value of the ferromagnetic tunnel junction magnetoresistive film exhibits a substantially constant value of 5 × 10 ⁻⁵ Ωcm ² or less. 11. The magnetic memory device according to claim 9, wherein the ferromagnetic tunnel junction magnetoresistive film has a temperature coefficient of ± 0.04% / ° C. or less. 12. The tunnel barrier layer has a film thickness of 3 nm.
The magnetic storage device according to any one of claims 9 to 11, wherein: 13. The tunnel barrier layer has a thickness of 2 nm.
The magnetic storage device according to any one of claims 9 to 11, wherein: 14. The magnetic storage device according to claim 9, wherein the magnetic recording medium is a flexible magnetic recording medium in which a magnetic recording layer is formed on a substrate such as a synthetic resin. . 15. The magnetic recording medium according to claim 9, wherein the magnetic recording medium is a hard magnetic recording medium in which a magnetic recording layer is formed on a hard substrate. Magnetic storage device. 16. The magnetic memory device according to claim 9, wherein the magnetic head is allowed to operate in a state where a gap between the magnetic head and the recording medium is 40 nm or less. 17. The magnetic memory according to claim 9, wherein the tunnel barrier layer has a natural oxide film on at least a surface of a conductive layer made of metal or semimetal. apparatus. 18. The layer formed of the metal or semimetal forming the tunnel barrier layer is made of aluminum (A
18. The magnetic storage device according to claim 9, wherein the magnetic storage device is one selected from l), Mg and lanthanoids. 19. The magnetic storage device according to claim 9, wherein the magnetic recording medium is used in a magnetic storage device having a disk shape. 20. The magnetic storage device according to claim 9, wherein the magnetic recording medium is used in a magnetic storage device in the form of a tape. 21. In the magnetic head, two opposing first magnetic shields and second magnetic shields, which are laminated on a ceramic serving as a slider, and two opposing first and second magnetic shields. A reproducing head using a reproducing element using the ferromagnetic tunnel junction magnetoresistive film existing between two magnetic shields, a first magnetic pole film, a coil sandwiched by an insulator, and a second magnetic pole film. 21. A recording head for recording a magnetic signal on a magnetic medium by using a leakage magnetic flux generated from a magnetic gap provided between the first and second magnetic poles. The magnetic storage device according to 1.