JP2798016B2 - Magnetoresistive element, magnetoresistive head and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetoresistive element, a magnetoresistive magnetic head and a method of manufacturing the same, and more particularly, to a magnetoresistive element for stabilizing magnetization with a permanent magnet film to reduce magnetic noise. In the effect type magnetic sensing element,
The present invention relates to an element structure for improving a manufacturing yield.

[0002]

2. Description of the Related Art With the recent development of high density magnetic recording, a magnetoresistive head (hereinafter abbreviated as MR head) has come into practical use as a magnetic head used for recording and reproduction. Have been. The shape of the MR head is generally as shown in FIG. 5, the magnetic sensitive section 1 of the magnetic film exhibiting magnetoresistance effect, the sense current applying means for indicia pressurizing the sensing current J in sensitive sections 1 (current source) I And a magnetic sensing unit resistance detecting means (voltage measuring unit) V for detecting a change in electric resistance of the magnetic sensing unit 1. Further, as shown in FIG. 6, the structure of the magnetic sensing unit 1 is a magnetoresistive film (hereinafter abbreviated as MR film) 1.
1 and an adjacent soft magnetic film (hereinafter referred to as Soft Adjacent Layer;
SAL film 13).

Normally, in order to ensure the linearity of the resistance change with respect to the external magnetic field H, the angle α of magnetization with respect to the applied current J of the MR film is set to about 45 °. At this time, MR
Let the saturation magnetic flux density and the film thickness of the film 11 be B _m and t _m , respectively.
The saturation magnetic flux density and the film thickness of the SAL film 13 are set to B _s and t _s respectively.
When the product of the saturation magnetic flux density and the film thickness of the SAL film 13 (B _s · t _s) in advance (B _m · t _m) sin4
It is set to be approximately equal to 5 °.

However, even when such conditions are set, as shown in the resistance-magnetic field response curve of FIG.
The phenomenon that the MR film 11 rapidly changes its resistance by a specific magnetic field was often observed. Such a phenomenon that causes a rapid change in the resistance of the MR film 11 is called Barkhausen noise. The cause of the Barkhausen noise is that the MR film 1
This is due to the existence of a magnetic domain in 1 and the abrupt movement of the domain wall which is the boundary of the magnetic domain.

As a method for reducing the rapid movement of the magnetic domain wall, as shown in FIGS. 5 and 6, permanent magnet films 2 are provided on both sides of a magnetic sensing portion 1 so that the magnetic field generated by the permanent magnet film 2 can be used. It is common practice to make the MR film 11 of the magnetic part 1 into a single magnetic domain. In this case, assuming that the saturation magnetic flux density and the film thickness of the permanent magnet film 2 are B _h and t _h , respectively, the saturation magnetic flux density and the film thickness of the permanent magnet film 2 are required to maintain good continuity of magnetic flux. The product (B _h · t _h ) with (B _m · t _m ) c
os45 °. Then, a favorable MR resistance-magnetic field response curve as shown in FIG. 8 is obtained, and the response curve becomes desirable as an MR head.

[0006]

Next, in order to prevent Barkhausen noise with good reproducibility, it is necessary to precisely control the saturation magnetic flux density and the film thickness of the permanent magnet film.
The saturation magnetic flux density and the film thickness of the permanent magnet film are set during the manufacturing process of the MR head. The presence or absence of Barkhausen noise cannot be confirmed until at least after the elements of the MR head are formed. Therefore, if the existence of Barkhausen noise is confirmed at that time, the element wafer of the MR head must be defective.

That is, in order to correct Barkhausen noise, it is necessary to change the characteristics of the completed permanent magnet film, but this is generally extremely difficult in the manufacturing process. That is, the conventional permanent magnet bias type M
With the R head, it has been difficult to improve the yield and reduce the manufacturing cost.

As a method of suppressing Barkhausen noise, it is effective to sufficiently increase the magnetic field generated from the permanent magnet film. However, when the generated magnetic field is increased, the resistance-magnetic field response curve shown in FIG. There is a drawback that the half width is increased and the magnetic field detection sensitivity is reduced.

[0009]

According to the MR element of the present invention, a magnetically sensitive portion formed of a magnetic film exhibiting a magnetoresistive effect, a sense current applied to the magnetically sensitive portion, and two sides of the magnetically sensitive portion are provided. Having magnetic domain stabilization pattern formed by provided permanent magnet film
The device is characterized in that the direction of magnetization of the magnetic domain stabilization pattern and the direction of application of the sense current are substantially non-parallel.

Also, the saturation magnetic flux density and the thickness of the magnetic film of the magnetic sensing portion are B _m and t _m , respectively, the angle between the magnetization direction of the magnetic film and the sense current application direction is α, and the sense current application direction is the angle between the magnetization direction of the permanent magnet film theta, each B _h a saturation magnetic flux density and the film thickness of the permanent magnet film, when a _{t h, (B m · t} m) cosα ≧ (B h · t h) The above θ may be determined so as to satisfy cos θ. The saturation magnetic flux density and the film thickness of the magnetic film of the magnetic sensing portion are respectively B _m and t _m , and the magnetization direction of the magnetic film and the direction of application of the sense current are formed. The angle α is approximately 45 °, and the saturation magnetic flux density and the film thickness of the permanent magnet film are respectively B
_{When h} and t _h , (B _m · t _m ) cosα <(B _h · th _h ) may be satisfied.

Further, the MR head according to the present invention is characterized in that the MR head is provided with these MR elements and magnetic shields from both sides in the film thickness direction.

Further, the method of manufacturing an MR head of the present invention
The resistance-magnetic field response of the MR element is measured while applying an AC magnetic field to the R element, and the magnetization direction of the permanent magnet film of the MR element is arbitrarily changed based on the measurement result to change the magnetization direction of the permanent magnet film. It is characterized by being optimized.

As described above, the present invention provides a magnetic sensing portion formed of a magnetic film exhibiting a magnetoresistive effect, a sense current applied to the magnetic sensing portion, and a permanent magnet film provided on both sides of the magnetic sensing portion. In the MR element having the magnetic domain stabilization pattern formed by the above, by setting the magnetization direction of the magnetic domain stabilization pattern substantially non-parallel to the sense current application direction, and changing the non-parallel angle after the MR element is formed, Barkhausen noise is suppressed without lowering the magnetic field detection sensitivity.

[0014]

Next, the present invention will be described with reference to the drawings. (First Embodiment) FIG. 1 is a configuration diagram showing a first embodiment of the present invention. Referring to FIG. 1, in the first embodiment, permanent magnet films 2 are arranged on both sides of a magnetosensitive portion 1 formed of an MR film having a saturation magnetic flux density Bm and a film thickness tm.
Further, a sense current applying means (current source) I and a magneto-sensitive section resistance measuring means (voltage measuring section) V are connected to the permanent magnet film 2 respectively. Reference numeral 15 denotes the magnetization direction of the magnetic sensing unit 1, reference numeral J denotes the direction of the sense current applied to the MR film (not shown) of the magnetic sensing unit 1, and reference numeral 25 denotes the magnetization direction of the permanent magnet film 2. ing.

Here, the product of the saturation magnetic flux density B _h and the thickness t _h of the permanent magnet film 2 is determined in advance in consideration of the tolerance and the allowance of the film forming process, and (B _m · t _m ) cos 45 ° <( B _h・ th _h ) ……………… (1) In addition, there is no particular strict restriction on the size. Therefore, it is not necessary to strictly control the saturation magnetic flux density and the film thickness during the film forming process, and the process yield is improved. (Second Embodiment) FIG. 2 is a configuration diagram showing a second embodiment of the present invention. Referring to FIG. 2, in the second embodiment, the angle between the sense current J applied to the MR film of the magnetosensitive portion 1 and the magnetization 15 is α. The angle α is set to approximately 45 °, for example, as shown in FIG. 8, so that an optimum bias can be obtained in the resistance-magnetic field response curve. Then, this setting, the product of the saturation flux density B _s and the thickness t _s of SAL13 shown in FIG. 3, in advance, MR
Sinα ≒ s of the product of the saturation magnetic flux density B _m of the film and the film thickness t _m
in 45 ° = 2 ^-1/2 times. That is, the _{(B s · t s) ≒} (B m · t m) sin45 ° .................. (2).

Further, for the permanent magnet film 2, each B _h a saturation magnetic flux density and the film thickness of the permanent magnet film 2, when a t _h, the product of the saturation flux density B _h and the thickness t _h ( B _m・
t _m ) is set to be larger than cos 45 ° with a margin. Therefore, the magnetization direction 25 of the permanent magnet film 2 remains unchanged.
Is set in the same direction as the sense current direction J, an extra magnetic flux is generated, an unnecessary magnetic field is applied to the magnetosensitive portion 1 in the current direction, and the half value width of the magnetic field-resistance curve shown in FIG. The magnetic sensitivity decreases.

In order to suppress the decrease in the magnetic sensitivity, the magnetization of the permanent magnet film is set so that the magnetic flux in the sense current direction of the MR film of the magnetic sensing portion is equal to the magnetic flux of the permanent magnet film in the same direction.
Set the direction of. That is, when the magnetization direction of the permanent magnet film and theta, have set theta to _{(B h · t h) cosθ} ≒ (B m · t m) cos45 ° ...... (3). (Third Embodiment) FIG. 4 is a configuration diagram showing a third embodiment of the present invention. Referring to FIG. 4, the third embodiment relates to a specific material configuration of the MR element. The MR film 11 is made of a NiFe film, and B _m ≒ 850.
0G, t _m ≒ 20 nm. Further, a Ta film having a thickness of 10 nm is used as the nonmagnetic film 12. Further, the SAL film 13
Is composed of an amorphous CoZrMo film and has a saturation magnetic flux density B _s ≒
6000 G, thickness t _s ≒ 20 nm. In this case, conditional expression (2) is satisfied.

Next, the permanent magnet film 2 has a thickness of 10 nm.
With the r film as the base, the saturation magnetic flux density B _h Ｃ
An oCrPt film is formed with a thickness t _h ≒ 20 nm by a sputtering film forming method. This satisfies conditional expression (1). Then, the angle θ is set so as to further satisfy the conditional expression (3).
Set.

Then, the permanent magnet film 2 becomes (B _h ·
t _h ) ≒ 160000 G · nm and MR film 1
1 is (B _m · t _m ) cos 45 ° @ 120,000 G · n
m, the condition (3) is satisfied when θ is set to {41}. (Embodiment 4) Embodiment 4 of the present invention with reference to FIG.
Will be described. The fourth embodiment is an example of an MR effect type magnetic head in which a permanent magnet film is used as a bias film for stabilizing the magnetic domain of the MR film of the magnetosensitive portion. In this example, the MR element including the magneto-sensitive part 1 and the permanent magnet film 2 having the film structure shown in the third embodiment is replaced with a NiFe alloy film lower shield 31 having a thickness of 2 μm.
And a shield type MR head provided with an insulating layer between the upper shield 32 and a 3 μm thick NiFe alloy film.

By adopting such a structure, an MR head for reproduction with high resolution is obtained. Although the recording element is omitted in this example, it is apparent that the present invention can be easily implemented even with a composite MR head combined with the recording element. Embodiment 5 Embodiment 5 of the present invention will be described with reference to FIGS. The fifth embodiment relates to a manufacturing method for determining a magnetization direction by magnetizing a permanent magnet film.
First, as shown in FIG. 10, a sense current applying means I and a voltage detecting means V for detecting a change in resistance of an MR element are connected to an MR head according to the present invention. Furthermore, resistance-magnetic field measuring means for obtaining a magnetic field-resistance response curve, AC magnetic field applying means for applying an external AC magnetic field H, magnetization direction rotating means for determining the magnetization direction of the permanent magnet film, A magnetizing means for applying a DC magnetic field Hh is provided.

FIG. 11 is a configuration diagram illustrating the process of magnetizing the permanent magnet film. Referring to FIG. 11, the magnetizing means related to the present process is an MR element (magnetic sensing unit 1,
AC magnetic field applying means 41 for applying an AC magnetic field H to the permanent magnet film 2), resistance-magnetic field measuring means 42 for measuring a resistance-magnetic field response, and a Barkhausen determination circuit 43 for determining the presence or absence of Barkhausen noise from the response Magnetic field direction rotating means 44 for changing the direction of the magnetizing magnetic field based on the result of the determination.
When magnetizing means 4 for applying the magnetizing magnetic field H _h permanent magnet film 2
5 Then, the magnetization direction of the permanent magnet film 2 is optimized by changing the magnetization direction according to the resistance-magnetic field response curve obtained from the resistance-magnetic field measuring means 42 so that Barkhausen noise does not occur.

[0022]

As described above, by using the present invention, an MR having a high yield and suppressing the generation of Barkhausen noise without lowering the magnetic field detection sensitivity.
An element, an MR head, and a method of manufacturing the same can be provided.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a configuration diagram showing a second embodiment of the present invention.

FIG. 3 is a configuration diagram showing a second embodiment of the present invention.

FIG. 4 is a configuration diagram showing a third embodiment of the present invention.

FIG. 5 is a diagram showing an example of a conventional magnetoresistance effect element.

FIG. 6 is a diagram showing an example of a conventional magnetoresistance effect element.

FIG. 7 is a diagram showing a resistance-magnetic field response curve that causes a rapid change in resistance in a certain magnetic field.

FIG. 8 is a diagram showing a good resistance-magnetic field response curve.

FIG. 9 is a perspective view showing a fourth embodiment of the present invention.

FIG. 10 is a configuration diagram showing a fifth embodiment of the present invention.

FIG. 11 is a configuration diagram for realizing a fifth embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Magnetic sensing part 2 Permanent magnet film 11 MR film 12 Non-magnetic film 13 SAL film (adjacent soft magnetic film) 15 MR film magnetization direction 25 Permanent magnet film magnetization direction 31 Lower shield 32 Upper shield 41 AC magnetic field applying means 42 Resistance-magnetic field Measuring means 43 Barkhausen noise determining means 44 Magnetic field direction rotating means 45 Magnetizing means H AC magnetic field I Sense current applying means (current source) J Sense current direction V Sensitive part resistance measuring means (Voltage measuring part) H _h Magnetizing magnetic field t _h permanent magnet MakumakuAtsu t _m MR MakumakuAtsu t _s SAL MakumakuAtsu

Claims (7)

(57) [Claims] 1. A magnetic sensing part formed of a magnetic film exhibiting a magnetoresistive effect, a sense current applied to the magnetic sensing part, and a magnetic domain formed by a permanent magnet film provided on both sides of the magnetic sensing part. A magnetoresistive element having a stable pattern, wherein the direction of magnetization of the magnetic domain stable pattern and the direction of application of the sense current are substantially non-parallel. 2. The saturation magnetic flux density and the thickness of the magnetic film of the magnetic sensing portion are B _m and t _m , respectively, the angle between the magnetization direction of the magnetic film and the direction of application of the sense current is α, and the sense current is α. Is the angle between the direction of application and the magnetization direction of the permanent magnet film, θ,
Saturation magnetic flux density and each thickness B _h of the permanent magnet film, t
_2. The magnetoresistive element according to claim 1, wherein, when _h is set, the angle θ is determined so as to satisfy (B _m · t _m ) cos α ≧ (B _h · th _h ) cos θ. 3. The saturation magnetic flux density and the film thickness of the magnetic film of the magnetic sensing portion are B _m and t _m , respectively, and the angle α between the magnetization direction of the magnetic film and the sense current application direction is approximately 45 °, saturation magnetic flux density and each thickness B _h of the permanent magnet film, when a t _h, the claims, which is a _{(B m · t m) cosα} <(B h · t h) 2. The magnetoresistance effect element according to claim 1. 4. A magnetoresistance effect type magnetic head comprising: the magnetoresistance effect element according to claim 1; and a magnetic shield from both sides of the magnetoresistance effect element in a film thickness direction. 5. A magnetoresistive effect type magnetic head comprising: the magnetoresistive effect element according to claim 2; and a magnetic shield from both sides of the magnetoresistive effect element in a film thickness direction. 6. A magnetoresistive effect type magnetic head comprising: the magnetoresistive element according to claim 3; and a magnetic shield comprising the magnetoresistive element from both sides in a film thickness direction. 7. The method of manufacturing a magnetoresistive effect type magnetic head according to claim 4, wherein a resistance of the magnetoresistive effect element is reduced by applying an AC magnetic field to the magnetoresistive effect element. The magnetic field response is measured, and the magnetization direction of the permanent magnet film of the magnetoresistive effect element is arbitrarily changed based on the measurement result to optimize the magnetization direction of the permanent magnet film. Of manufacturing a magnetoresistive magnetic head.