JP5007916B2 - Magnetic sensor - Google Patents

Description

The present invention is a magnetic sensor used to measure displacement with a magnetic medium in a non-contact manner, and has a temperature characteristic of the same electric resistance as a spin valve giant magnetoresistive film and a spin valve giant magnetoresistive film. The present invention relates to a magnetic sensor provided with a resistive film.

In the field of industrial measurement, low-cost magnetosensitive elements such as Hall elements are often used to detect physical variables such as position and rotation angle without contact with a magnetic medium. When it is necessary to perform detection with high sensitivity, a magnetic sensor having an anisotropic magnetoresistive film (hereinafter referred to as an AMR film) whose relative speed with respect to a magnetic medium does not depend on reproduction output is used. However, a magnetic sensor using an AMR film has a small rate of change in magnetoresistance of about 3%, so that the output signal voltage obtained is small. Therefore, a magnetic sensor having a giant magnetoresistive film (GMR film) having a large magnetoresistive change rate and an advantage that it can be handled as a simple two-terminal resistor on a circuit has been attracting attention, and its practical application has been studied. .

As the giant magnetoresistive film, a coupled GMR artificial lattice film (hereinafter referred to as a coupled GMR film) in which the magnetization directions of adjacent magnetic layers are opposite to each other via a nonmagnetic layer is known. Since the combined GMR film has the same resistance change characteristic with respect to the magnetic field change as the AMR film, it is easy to use AM.
Replacement from the R film is possible. Since the combined GMR film has a large resistance change rate of 10% or more, a large output can be obtained. However, since the operating magnetic field intensity causing the maximum resistance change is large, a large operating magnetic field generating means is required. In addition, since the electrical resistance of the coupled GMR film is as small as about 1/2 to 1/3 that of the AMR film, it is difficult to reduce the power consumption of the magnetic sensor. Therefore, there is a problem that the use of the magnetic sensor using the coupled GMR film is limited.

As a film showing a magnetoresistance change rate comparable to that of a coupled GMR film in a relatively weak magnetic field strength region,
There is a spin valve type giant magnetoresistive film (hereinafter referred to as SVGMR film). The SVGMR film is used for a magnetic head of a hard disk storage device (HDD). The SVGMR film is
As disclosed in Patent Document 1, a magnetization fixed layer and a nonmagnetic conductive layer whose magnetization direction does not change even if the direction of the external magnetic field changes, and a magnetization free layer whose magnetization direction changes following the change of the external magnetic field It is composed of Sensor element processed SVGMR film (hereinafter referred to as SVGMR element)
Since the electric resistance is 5 to 6 times larger than that of a sensor element obtained by processing a coupled GMR film, it is easy to reduce power consumption when used in a magnetic sensor. Moreover, 1-160 (A / m) [about 0.006
˜20 (Oe)] and operates in a relatively small magnetic field strength region. Hereinafter, the magnetoresistive film of the present application is referred to as an SVGMR film unless otherwise specified.

Japanese Patent No. 3040750

FIG. 10 shows a magnetic sensor and a magnetic medium. A magnetic sensor 60 is arranged to face the rotating magnetic medium 61 with a predetermined gap (gap). The magnetic sensor 60 includes a plurality of magnetic sensor elements 51. In the magnetic sensor element 51, an SVGMR element 27 whose electric resistance is changed by a magnetic field and a fixed resistance element 28 formed of a fixed resistance film are connected in series. The other end of the fixed resistance element 28 is grounded, and the other end of the SVGMR element 27 is connected to the power supply voltage Vcc. SV
A midpoint potential is taken from the connection point 31 between the GMR element 27 and the fixed resistance element 28, and this voltage becomes the output voltage of the magnetic sensor 60. Since the fixed resistance element 28 does not change its electric resistance due to a magnetic field, the electric resistance is substantially constant and functions as a comparison resistance of the SVGMR sensor element 27. SVGMR
When the element 27 detects the leakage magnetic field of the magnetic medium 61, the electrical resistance changes and the midpoint potential changes. This change in the midpoint potential is detected as a relative position signal between the magnetic medium and the magnetic sensor.

A bridge can be formed by using two magnetic sensor elements 51. FIG. 11 shows a magnetic sensor element 52 having a bridge. The magnetic sensor element 51 is connected in parallel in the reverse direction. By assembling the bridge in this manner, the effect of amplifying the amount of change in electrical resistance can be obtained with the SVGMR sensor elements 27a and 27b whose electrical resistance changes due to a magnetic field. Between the connection points 34a and 34b, an output voltage approximately twice that of the connection point 31 in FIG. 10 is obtained.

However, when the magnetic sensor element 51 is formed using the SVGMR film and a fixed resistance film made of a metal conductor such as copper (Cu), the magnetic sensor is exposed to high temperature or low temperature due to the difference in temperature characteristics of electric resistance. When used in an environment, the midpoint potential of the magnetic sensor element changes and the displacement cannot be detected accurately. When using a magnetic sensor as an in-vehicle sensor, 150
Although heat resistance of at least ° C. is required, for example, the temperature coefficient of Cu is 4.3 × 10 ⁻³ (deg. ^−
1 ), whereas the temperature coefficient of the SVGMR element is 1.0 to 1.3 × 10 ⁻³ (deg).
. ⁻¹ ) and they are not equal, the midpoint potential of the bridge circuit changes due to changes in the ambient temperature. The temperature coefficient of metal aluminum, gold, and silver used for other conductors is 4.0 to 4.0.
4.2 × 10 ⁻³ (deg. ⁻¹ ), and the difference from the temperature coefficient of the SVGMR element is large.

A metal close to the temperature coefficient of the SVGMR film can be selected from an alloy system. For example, there are nickel alloy alumel containing aluminum and manganese, copper and zinc alloy brass, platinum and rhodium alloy, and the temperature coefficient thereof is 1.2 to 1.4 × 10 ⁻³ (deg. ⁻¹⁾ . ) And SV
Very close to GMR film but not the same value. Also, since the sheet resistance value is different from that of the SVGMR film, it is very difficult to match the electric resistance value by changing the shape and thickness of the element. Further, an extra film forming apparatus and a sputtering target material are required to obtain the fixed resistance film.

The object of the present invention is to form a magnetic sensor element with an element formed of an SVGMR film and a fixed resistance film having the same electric resistance value and temperature characteristic of electric resistance, and to obtain a stable output characteristic with respect to changes in ambient temperature. It is to provide a sensor.

The magnetic sensor of the present invention has a sensor element formed of a magnetoresistive effect film whose electrical resistance changes in response to an external magnetic field, and the magnetoresistive effect film and the electrical resistance have the same temperature characteristics and no electrical field in the absence of an external magnetic field. It is preferable that a bridge circuit is formed by a sensor element formed of a fixed resistance film which has the same resistance and hardly changes its resistance with an external magnetic field.

A magnetoresistive film formed on a substrate is formed of a single layer or a plurality of layers, a nonmagnetic conductive layer, a magnetization fixed layer and a magnetization free layer sandwiching the nonmagnetic conductive layer, and formed next to the magnetization fixed layer. Preferably, the SVGMR film is composed of a multilayer portion made of an antiferromagnetic layer and a protective film formed on the uppermost layer.

In the multilayer portion, the magnetization fixed layer and / or the magnetization free layer is preferably composed of a single layer or a plurality of layers.

The SVGMR film may be an SVGMR film having any structure of a bottom type, a top type, a laminated ferri pinned layer type, a laminated ferri free layer type, and a spin filter type. Also,
Plasma treatment can be performed for the purpose of planarizing the interface at any of the stacked interfaces.

The fixed resistance film is preferably made of the same material as that of the magnetoresistive effect film, and a part of the stacking order is preferably changed.

The fixed resistance film constituting the bridge circuit has a structure in which the stacking order of the nonmagnetic conductive layer and the magnetization free layer of the SVGMR film or the stacking order of the nonmagnetic conductive layer and the magnetization fixed layer is switched. Thus, the spin-dependent scattering between the magnetization free layer and the magnetization fixed layer through the film can be eliminated, and a structure in which the GMR effect is not exhibited can be obtained. Further, since the fixed resistance film uses the same material and the same film thickness as the SVGMR film, the electric resistance value is the same and the temperature characteristics of the electric resistance are the same, so that the change in the midpoint potential due to the change in the ambient temperature is suppressed. be able to.

  It is preferable that the magnetoresistive film and the fixed resistance film are formed on the same substrate.

The SVGMR film and the fixed resistance film can be directly formed on the same substrate by combining the photolithography process and the sputter film formation process. Since the SVGMR film and the fixed resistance film have a configuration in which the stacking order is partially changed, they can be formed with the same sputtering apparatus and can have the same film thickness distribution. Variations in temperature characteristics can be reduced.

The fixed resistance film can be adjusted in electric resistance value by changing the film thickness of the nonmagnetic conductive layer.

Since most of the sense current flowing through the fixed resistance film flows through the nonmagnetic conductive layer, the electric resistance value reacts best with the film thickness of the nonmagnetic conductive layer. Therefore, the electrical resistance value of the resistance film can be finely adjusted only by adjusting the film thickness of the nonmagnetic conductive layer without changing the film thickness other than the nonmagnetic conductive layer.

The SVGMR film and the fixed resistance film can have the same electric resistance value because they are only partially different from each other in the stacking order of the films. Further, by configuring the magnetic sensor element with the SVGMR film and the fixed resistance film having the same temperature characteristics of electric resistance, a magnetic sensor that can obtain stable output characteristics with respect to changes in ambient temperature can be realized.

Hereinafter, the present invention will be described in detail based on examples with reference to the drawings. In order to make the explanation easy to understand, the same reference numerals are used for the same parts and parts. The SVGMR film and the fixed resistance film and elements formed using these are used in the same manner. For example, the SVGMR film may refer to an element formed using not only the SVGMR film but also the SVGMR film.

Before describing the details of the implemented SVGMR film and the fixed resistance film, the reason why the SVGMR film becomes a fixed resistance film by partially changing the stacking order of the SVGMR film will be described in detail with reference to FIG. FIG. 1 shows a SVGMR film and a fixed resistance film of an antiferromagnetic layer bottom type (bottom type). FIG. 1a)
This is a bottom type SVGMR film 101 formed by sputtering a base layer 12, an antiferromagnetic layer 13, a magnetization fixed layer 14, a nonmagnetic conductive layer 15, a magnetization free layer 16, and a protective layer 17 in this order on a substrate 11. The magnetization of the magnetization free layer 16 is rotated by the external magnetic field, and the electrical resistance changes depending on the relative angle formed with the magnetization direction of the magnetization fixed layer 14. FIG. 1 b) shows a fixed resistance film 102 in which the order of partial stacking of SVGMR is changed. On the substrate 11, an underlayer 12, an antiferromagnetic layer 13, a magnetization fixed layer 14, a magnetization free layer 16, a nonmagnetic conductive layer 15, Sputter deposition is performed in the order of the protective layer 17. The fixed resistance film 102 has a structure in which the stacking order of the magnetization free layer 16 and the nonmagnetic conductive layer 15 of the SVGMR film 101 is switched. For this reason, the GMR effect through the nonmagnetic conductive layer 15 does not appear, and the change in the electric resistance value of the fixed resistance film 102 due to the external magnetic field becomes almost zero.

If the stacking order of the nonmagnetic conductive layer 15 and the magnetization free layer 16 is changed, the G of the fixed resistance film 102 is changed.
The reason for the disappearance of the MR effect is to minimize the movement of the position of the nonmagnetic conductive layer 15 through which most of the sense current flows in the stacked structure of the SVGMR element. For example, on the basis of the spin valve structure, the nonmagnetic conductive layer 15 and the magnetization fixed layer may be used in order to prevent the GMR effect from being manifested without substantially changing the material, film forming conditions and film thickness of each layer. 14 may be replaced. However, the magnetization fixed layer 14 is in contact with the antiferromagnetic layer 13 so that the magnetization direction is strongly fixed by exchange coupling, and it is difficult to react to an external magnetic field. Therefore, it is not preferable to separate the magnetization fixed layer and the antiferromagnetic layer because the magnetization fixed strength of the magnetization fixed layer is weakened.

When the nonmagnetic conductive layer 15 and the magnetization fixed layer 14 are exchanged, the stacking order as shown in FIG. It is preferable to replace the antiferromagnetic layer 13 at the same time, and the fixed resistance film 1
The layered structure of 02 ′ has the following: underlayer 12 / nonmagnetic conductive layer 15 / antiferromagnetic layer 13 / magnetization fixed layer 14
/ Magnetization free layer 16 / protection layer 17 is required. However, the fixed resistive film 102 in FIG.
In the stacked structure of ', the position of the nonmagnetic conductive layer 15 is greatly different from the position of the nonmagnetic conductive layer 15 of the SVGMR film 101 in FIG. 2a). Due to the influence of the thick antiferromagnetic film 13, it is difficult to control the film thickness and film thickness distribution. Also from this, the non-magnetic conductive layer 15 and the magnetization free layer 16 are interchanged to obtain the fixed resistance film 102. FIG. 1a) is preferable.

The amount of change dR in the electrical resistance of each of the SVGMR film 101 and the fixed resistance film 102 will be described. The resistance change amount of the SVGMR film 101 is dR1, and the resistance change amount of the fixed resistance film 102 is dR2.
Then, dR1 = [resistance variation due to GMR effect] + [resistance variation due to AMR effect]
+ [Resistance change amount due to temperature change], dR2 = [resistance change amount due to AMR effect] + [resistance change amount due to temperature change]. Most of the sense current flowing through the SVGMR film 101 flows through the nonmagnetic conductive layer 15, and most of the sense current of the fixed resistance film 102 flows through the nonmagnetic conductive layer 15. In addition, since most of the shunt current flows through the antiferromagnetic layer 13 having the largest film thickness in the laminated film,
The current flowing in the magnetization fixed layer 14 and the magnetization free layer 16 is very small. Therefore, the [resistance change amount due to the AMR effect] is extremely smaller than the [resistance change amount due to the GMR effect], and can be ignored. Even if there is a small amount of [resistance change due to the AMR effect], the SVGMR film 101 and the fixed resistance film 102 having the same material and film thickness are combined to form a bridge circuit as shown in FIG. By taking the above, it is possible to cancel the [resistance change amount due to the AMR effect].

When the magnetic sensor 60 is used in an ambient environment where the temperature change is small, such as in a room, the above-described [resistance change amount due to temperature change] can be ignored. However, for example, when used in a severe ambient environment at a high temperature of 100 ° C. or higher or a low temperature of 0 ° C. or lower, [resistance change due to temperature change] cannot be ignored. When the bridge circuit as shown in FIG. 11 is composed of an SVGMR film and a fixed resistance film made of different materials, due to the difference in temperature characteristics of the electrical resistance between the SVGMR film and the fixed resistance film, the resistance change amount due to temperature change is A difference occurs and the midpoint potential changes, making it impossible to measure with high accuracy. Since the SVGMR film 101 and the fixed resistance film 102 of the present patent application use the same material and the film thickness of each layer constituting the multilayer film is the same, even if it is used in an ambient environment where the temperature changes greatly [ Since there is no difference in the resistance change amount], the midpoint potential does not change, and a magnetic sensor capable of measuring with high accuracy can be provided.

FIG. 3 is a cross-sectional view of the stacked structure of the SVGMR film 111 and the fixed resistance film 112 that is implemented.
The material and film thickness of each layer are shown. The SVGMR film 111 shown in FIG. 3A) is NiFeCr (4 nm) / MnPt (15 nm) / CoFe from the side of the substrate 11 having an electrical insulating or insulating layer.
(2 nm) / Cu (2 nm) / CoFe (1 nm) -NiFe (3 nm) / Ta (3 nm
Sputtered films were stacked in the order of NiFeCr is the underlayer 12, and MnPt is the antiferromagnetic layer 13.
The substrate side CoFe corresponds to the magnetization fixed layer 14, Cu corresponds to the nonmagnetic conductive layer 15, CoFe and NiFe on the protection layer side correspond to the magnetization free layer 16, Ta corresponds to the protection layer 17, and FIG. In FIG. 1 a), the magnetization free layer 16 is represented by one layer, but when implemented, it is a two-layer film of CoFe and NiFe. Compared to the case where Cu and NiFe of the nonmagnetic conductive layer 15 are directly laminated, Cu and Ni
By inserting CoFe thinly between Fe, the magnetoresistance change rate is increased. Therefore, the magnetization free layer 16 is a two-layer film of CoFe and NiFe. When the magnetization free layer 16 has four layers,
The stacking order of Cu of the nonmagnetic conductive layer 15 and CoFe and NiFe of the magnetization free layer 16 is not changed from the aspect of magnetoresistance change rate.

FIG. 3 b) shows a fixed resistance film 112 combined with the SVGMR film 111. Layers swapped by arrows are shown between FIGS. 3a) and 3b). Nonmagnetic conductive layer 1 of SVGMR film 111
5 and the magnetization order of the magnetization free layer 16 are interchanged. Further, the CoF of the magnetization free layer 16
e and NiFe were replaced. If the replacement of CoFe and NiFe of the magnetization free layer 16 is not performed, the CoFe of the magnetization fixed layer 14 is continuously laminated, and the thickness of the CoFe increases. An increase in the film thickness of CoFe, which is a ferromagnetic material, is not preferable because it leads to an increase in the aforementioned [resistance change amount due to the AMR effect]. The fixed resistance film 112 is NiF from the substrate 11 side.
eCr (4 nm) / MnPt (15 nm) / CoFe (2 nm) / NiFe (3 nm) −
CoFe (1 nm) / Cu (2 nm) / Ta (3 nm) were laminated in this order.

FIG. 4 shows the temperature characteristics of the sheet resistance (Rs) and magnetoresistance change rate (dR / R) of the SVGMR film 111 and the fixed resistance film 112. Rs and dR / R were measured by heating the sample film in a vacuum from room temperature to 350 ° C. and measuring by a four-terminal method. The measurement of dR / R is a maximum of 7.9 (kA / m) (1 in the magnetization direction of the magnetization fixed layer and the opposite direction, respectively.
Measurement was performed by applying a magnetic field of 00 (Oe). R of SVGMR film 111 at room temperature
s is 19.6 (Ω / □), dR / R is 9.2 (%), and Rs of the fixed resistance film 112 is 19.4.
(Ω / □) and dR / R were 0.2% or less. Since dR / R 0.2% of the fixed resistance film 112 is a value lower than the measurement limit value of the measuring instrument, the magnetoresistance change rate is a level that can be said to be substantially zero. Although not shown, the temperature characteristic of the electrical resistance is SVGMR in the temperature range of room temperature to 350 ° C.
Rs of the film 111 and the fixed resistance film 112 show the same temperature characteristic, and the temperature coefficient of the electric resistance is 1.
2 × 10 ⁻³ (deg. ⁻¹ ). Although the dR / R of the SVGMR film 111 decreases as the temperature increases, the dR / R of the fixed resistance film 112 is substantially zero regardless of the temperature and does not exhibit a magnetoresistive effect. FIG. 10 shows a sensor element formed by the SVGMR film 111 and the fixed resistance film 112.
By forming the magnetic sensor elements 51 and 52 shown in FIG. 11, a magnetic sensor in which the midpoint potential does not change even when the ambient temperature of the magnetic sensor 60 changes is obtained.

FIG. 5 shows an antiferromagnetic layer-mounted type (top type) SV according to a second embodiment of the present invention.
A GMR film and a fixed resistance film are shown. Antiferromagnetic layer bottom type (bottom type) of Example 1
This is a structure in which the stacking order of the SVGMR films is substantially reversed. As shown in FIG. 5 a), the SVGMR film 121 is formed from the base layer 12, the magnetization free layer 16, the nonmagnetic conductive layer 15, the magnetization fixed layer 14, the antiferromagnetic layer 13, and the protective layer 17 from the substrate 11 side. . The material and film thickness are NiFeC from the substrate 11 side.
r (4 nm) / NiFe (3 nm) -CoFe (1 nm) / Cu (2 nm) / CoFe (
2 nm) / MnPt (15 nm) / Ta (3 nm) in this order, an antiferromagnetic layer placed type (top type) SVGMR film 121 in which sputtering films are stacked in this order. Fig. 5b) shows the fixed resistive film 1
22 is shown. Since the order of the nonmagnetic conductive layer 15 and the magnetization free layer 16 of the SVGMR film 121 is switched, the base layer 12, the nonmagnetic conductive layer 15, the magnetization free layer 16, the magnetization fixed layer 14, and the antiferromagnetic layer are arranged from the substrate 11 side. 13, the fixed resistance film 122 is formed by the protective layer 17. The film material and the film thickness are NiFeCr (4 nm) / Cu (2 nm) / CoFe (1 nm) -Ni from the substrate 11 side.
Sputtered films were stacked in the order of Fe (3 nm) / CoFe (2 nm) / MnPt (15 nm) / Ta (3 nm).

FIG. 6 shows a bottom laminated ferri-fixed layer type SVGMR film and a fixed resistance film according to a third embodiment of the present invention. As shown in FIG. 6a), NiFeCr (4 nm) is formed from the substrate 11 side.
) / MnPt (12 nm) / CoFe (1.8 nm) -Ru (0.9 nm) -CoFe (
2.2 nm) / Cu (2 nm) / CoFe (1 nm) -NiFe (2 nm) / Ta (3 n
This is a bottom laminated ferri-fixed layer type SVGMR film 131 in which sputtered films are laminated in the order of m). NiFeCr is the underlayer 12, MnPt is the antiferromagnetic layer 13, Ru on the underlayer side and CoFe sandwiching the Ru are magnetization fixed layers 14, Cu is the nonmagnetic conductive layer 15, CoFe and NiF on the protective layer side
e corresponds to the magnetization free layer 16, and Ta corresponds to the protective layer 17. FIG. 5b) shows the fixed resistance film 13.
2 is shown. The stacking order of the nonmagnetic conductive layer 15 and the magnetization free layer 16 of the SVGMR film 131 was switched, and the order of CoFe and NiFe of the magnetization free layer was switched. The film material and film thickness are determined from the substrate 11 side by NiFeCr (4 nm) / MnPt (12 nm) / CoFe (1.8 nm) -Ru (
0.9 nm) -CoFe (2.2 nm) / NiFe (2 nm) -CoFe (1 nm) / C
The layers were stacked in the order of u (2 nm) / Ta (3 nm).

FIG. 7 shows a bottom laminated ferri-fixed layer and laminated ferri-free layer type SVGMR film and a fixed resistance film according to a fourth embodiment of the present invention. As shown in FIG. 7a), NiFeCr (4 nm) / MnPt (12 nm) / CoFe (1.5 nm) -Ru (0
. 9 nm) -CoFe (2 nm) / Cu (2 nm) / CoFe (1 nm) -NiFe (2
nm) -Ru (0.9 nm) -NiFe (2 nm) / Ta (3 nm) in this order are a bottom laminated ferri pinned layer and a laminated ferri free layer type SVGMR film 141 in this order. NiFeCr is the underlayer 12, MnPt is the antiferromagnetic layer 13, Ru on the underlayer side and CoFe sandwiching this are the magnetization fixed layer 14, Cu is the nonmagnetic conductive layer 15, CoFe on the protective layer side and Ru in contact therewith are sandwiched NiFe corresponds to the magnetization free layer 16, and Ta corresponds to the protective layer 17. The fixed resistance film 142 shown in FIG. 7b) is composed of the nonmagnetic conductive layer 15 and the magnetization free layer 16 of the SVGMR film 141.
The order of stacking was changed, and CoFe of the magnetization free layer and NiFe on the substrate side of the magnetization free layer were changed. The film material and film thickness are determined from the substrate 11 side by NiFeCr (4 nm) / MnPt (12 n
m) / CoFe (1.5 nm) -Ru (0.9 nm) -CoFe (2 nm) / NiFe (
2 nm) -CoFe 1 nm) -Ru (0.9 nm) -NiFe (2 nm) / Cu (2 nm
) / Ta (3 nm).

FIG. 8 shows a top laminated ferri-fixed layer type SVGMR film and a fixed resistance film according to a fifth embodiment of the present invention. As shown in FIG. 8a), NiFeCr (4 nm) is formed from the substrate 11 side.
) / NiFe (2 nm) -CoFe (1 nm) / Cu (2 nm) / CoFe (2 nm)-
Ru (0.9 nm) -CoFe (1.5 nm) / MnPt (12 nm) / Ta (3 nm)
The top laminated ferri-fixed layer type SVGMR film 151 in which the sputtered films are laminated in this order. NiFeCr is an underlayer 12, NiFe in contact with the underlayer, and CoFe formed thereon
Represents the magnetization free layer 16, Cu represents the nonmagnetic conductive layer 15, Ru on the protective layer side and CoFe sandwiching the Ru correspond to the magnetization fixed layer 16, MnPt corresponds to the antiferromagnetic layer 13, and Ta corresponds to the protective layer 17, respectively. FIG.
The fixed resistance film 152 shown in b) includes the nonmagnetic conductive layer 15 of the SVGMR film 151 and the magnetization free layer 1.
The stacking order of No. 6 was changed, and CoFe and NiFe of the magnetization free layer were changed. The film material and the film thickness are NiFeCr (4 nm) / Cu (2 nm) / CoFe (1 nm) from the substrate 11 side.
-NiFe (2 nm) / CoFe (2 nm) -Ru (0.9 nm) -CoFe (1.5 n
m) / MnPt (12 nm) / Ta (3 nm).

FIG. 9 shows a top laminated ferri-fixed layer and laminated ferri-free layer type SVGMR film and fixed resistance film according to a sixth embodiment of the present invention. As shown in FIG. 9a), NiFeCr (4 nm) / NiFe (2 nm) -Ru (0.9 nm) -NiFe (2n) from the substrate 11 side.
m) -CoFe (1 nm) / Cu (2 nm) / CoFe (2 nm) -Ru (0.9 nm)
-Top laminated ferri pinned layer and laminated ferri free layer type SVGMR film 161 in which sputtered films are laminated in the order of CoFe (1.5 nm) / MnPt (12 nm) / Ta (3 nm)
It is. NiFeCr is the underlayer 12, Ru on the underlayer side and NiFe sandwiching this, and CoFe deposited thereon is the magnetization free layer 16, Cu is the nonmagnetic conductive layer 15, Ru on the protective layer side and CoFe sandwiching this 9b), in which MnPt corresponds to the antiferromagnetic layer 13 and Ta corresponds to the protective layer 17, respectively, is a stack of the nonmagnetic conductive layer 15 and the magnetization free layer 16 of the SVGMR film 161. The order was changed, and CoFe of the magnetization free layer and NiFe on the protective layer side of the magnetization free layer were changed. The film material and film thickness were determined from NiFeCr (4n from the substrate 11 side.
m) / Cu (2 nm) / NiFe (2 nm) -Ru (0.9 nm) -CoFe (1 nm)
-NiFe (2 nm) / CoFe (2 nm) -Ru (0.9 nm) -CoFe (1.5 n
m) / MnPt (12 nm) / Ta (3 nm).

Also in Examples 2 to 6, the SVGMR film and the fixed resistance film forming the bridge circuit had the same Rs as in Example 1, and the temperature characteristics of Rs were the same in the temperature range of room temperature to 350 ° C. The temperature coefficient is 1. for all the membranes of Examples 2-6. It was in the range of ˜1.2 × 10 ⁻³ (deg. ⁻¹ ) and agreed well. Further, in any of the fixed resistance films of Examples 2 to 6 in which the stacking order was changed from that of the SVGMR film, dR / R was 0.2% or less in a temperature range of room temperature to 350 ° C. dR /
Since R0.2% or less is a value lower than the measurement limit value of the measuring instrument, it can be said that the magnetoresistance change rate is substantially zero.

It is a figure explaining the SVGMR film | membrane and fixed resistance film | membrane of the antiferromagnetic layer bottom type (bottom type) of this invention. It is a figure explaining the laminated structure when replacing the nonmagnetic conductive layer and magnetization fixed layer of this invention. It is a figure explaining the laminated structure of a SVGMR film | membrane and fixed resistance film | membrane of the antiferromagnetic layer bottom type (bottom type) of this invention. It is a figure explaining the temperature characteristic of sheet resistance (Rs) and magnetoresistance change rate (dR / R) of a SVGMR film | membrane and a fixed resistance film | membrane. It is a figure explaining the laminated structure of the SVGMR film | membrane of an antiferromagnetic layer on-board type (top type) and a fixed resistance film | membrane which is 2nd Example of this invention. It is a figure explaining the laminated structure of the bottom laminated ferri fixed layer type SVGMR film | membrane and fixed resistance film | membrane which is the 3rd Example of this invention. It is a figure explaining the laminated structure of the bottom laminated ferri fixed layer and laminated ferri free layer type SVGMR film | membrane and fixed resistance film which are the 4th Example of this invention. It is a figure explaining the laminated structure of the top laminated ferri fixed layer type SVGMR film | membrane and fixed resistance film which is the 5th Example of this invention. It is a figure explaining the laminated structure of the top laminated ferri fixed layer and laminated ferri free layer type SVGMR film | membrane and fixed resistance film which are the 6th Example of this invention. It is a figure explaining a magnetic sensor and a magnetic medium. It is a figure explaining the magnetic sensor element which built the bridge.

Explanation of symbols

11 substrate, 12 underlayer,
13 antiferromagnetic layer, 14 magnetization fixed layer,
15 nonmagnetic conductive layer, 16 magnetization free layer,
17 protective layer, 27 SVGMR element,
28 fixed resistance elements, 31, 32, 33, 34 terminals,
51, 52 Magnetic sensor element, 60 Magnetic sensor,
61 magnetic media,
101, 111, 121, 131, 141, 151, 161 SVGMR film,
102, 112, 122, 132, 142, 152, 162 Fixed resistance film.

Claims (2)

A bridge circuit is formed with a sensor element formed of a magnetoresistive film whose electric resistance changes in response to an external magnetic field and a sensor element formed of a fixed resistance film,
The sensor element formed of the fixed resistance film has a temperature characteristic of electric resistance equivalent to that of the magnetoresistive effect film, electric resistance in the absence of an external magnetic field is equivalent to that of the magnetoresistive effect film, and electric resistance is generated by the external magnetic field. Is almost unchanged,
The fixed resistance film and the magnetoresistive film are laminated films,
The fixed resistance film is made of the same material as the magnetoresistive effect film, and is configured such that the stacking order of the magnetoresistive effect film is partially replaced with a stacking order.
A magnetic medium that leaks a magnetic field detectable by a sensor element formed of the magnetoresistive film;
The magnetic medium is rotatable;
The bridge circuit is opposed to the peripheral surface of the magnetic medium,
The nonmagnetic conductive layer of the fixed resistance film is different in thickness from the nonmagnetic conductive layer of the magnetoresistive effect film. The magnetoresistive effect film is formed adjacent to the underlayer formed on the substrate, the nonmagnetic conductive layer, the magnetization fixed layer and the magnetization free layer sandwiching the nonmagnetic conductive layer, and the magnetization fixed layer. The magnetic sensor according to claim 1 , wherein the magnetic sensor is a spin valve type giant magnetoresistive film (SVGMR film) having a magnetic layer.

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