JP2002071775A - Magnetometrioc sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the detection accuracy of the direction of an external magnetic field by improving the temperature characteristic of a magnetometric sensor using a magnetic tunnel effect element. SOLUTION: The magnetometric sensor is provided with a first magnetic tunnel effect element 31, a second magnetic tunnel effect element 32 whose area is smaller than the area of the element 31 and whose sensitivity is lowered and a DC constant voltage source 33. The magnetometric sensor is constituted of a half-bridge circuit wherein the element 31 and the element 32 are connected in series, the voltage source 33 is connected in series with them and a voltage across both ends of the element 32 is taken out as an output voltage Vout. Thereby, the output voltage Vout becomes Vin/2 irrespective of an ambient temperature when the external magnetic field is '0', and it becomes a different value even when the ambient temperature is changed as long as the direction of the external magnetic field is different.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixed magnetic layer whose magnetization direction is fixed to a predetermined direction, a free magnetic layer whose magnetization direction changes according to an external magnetic field, the fixed magnetic layer and the free magnetic layer. The present invention relates to a magnetic sensor using a magnetic tunnel effect element including an insulating layer interposed between a magnetic layer and a magnetic layer.

[0002]

2. Description of the Related Art Hitherto, a magnetoresistive effect element (AMR element) utilizing an anisotropic MR effect or a giant magnetoresistive element (GMR element) utilizing a giant magnetoresistive effect has been widely known. On the other hand, recently, a magnetic tunnel effect element (TMR element) has attracted attention as an element having a higher magnetoresistance change rate and a higher sensitivity than an AMR element or a GMR element, and application development of the element to a magnetic sensor has been promoted. ing.

[0003]

However, there is a problem that the magnetic tunnel effect element is difficult to use as a magnetic sensor because of its poor temperature characteristics. As an example,
FIG. 17 shows changes in the resistance value R with respect to the external magnetic field H of a certain magnetic tunnel effect element when the environmental temperature is 25, 90, and 150 ° C., by lines A, B, and C, respectively. As understood from FIG.
Even if the direction of the external magnetic field H is different, the resistance value R indicated by the element may be the same due to a change in the environmental temperature. Therefore, such an element is used as a magnetic sensor for detecting the direction of the external magnetic field. It is difficult.

[0004]

SUMMARY OF THE INVENTION Generally, the sensitivity of a magnetic tunnel effect element decreases as the area decreases. In particular, when the element has a rectangular shape, the sensitivity tends to be governed by the length (width) of the short side rather than the length of the long side. According to the present invention, magnetic tunnel effect elements having different sensitivities are formed by utilizing these characteristics (that is, different areas), and a magnetic sensor including a half-bridge circuit or a full-bridge circuit is formed using the elements. To provide a magnetic sensor having improved temperature characteristics.

More specifically, one of the features of the present invention is that a DC voltage source, a fixed magnetization layer in which the direction of magnetization is fixed to a predetermined direction, and a direction in which the direction of magnetization changes according to an external magnetic field. A magnetic tunnel effect element comprising: a magnetic layer; and a magnetic tunnel effect element including an insulating layer sandwiched between the fixed magnetic layer and the free magnetic layer. And a second magnetic tunnel effect element, wherein the second element is smaller than the first area.
Are connected in series to the DC voltage source to output a voltage across either of the magnetic tunnel effect elements.

[0006] In this case, the magnetic tunnel effect element having the first area and the magnetic tunnel effect element having the second area may have the same or different resistance values. Further, the two magnetic tunnel effect elements may be formed on the same substrate, or each magnetic tunnel effect element may be formed on an independent substrate. The “magnetic tunnel effect element” includes a “magnetic tunnel effect element group in which a plurality of magnetic tunnel effect elements in which the directions of fixed magnetization of the fixed magnetization layers are substantially the same are electrically connected in series”. included.

The above features are shown schematically in FIG. As shown in FIG. 1, the voltage across the magnetic tunnel effect element having the second area is the output voltage Vout, the voltage of the DC voltage source is Vin, and the magnetic tunnel effect having the first area and the second area. Assuming that the resistance values of both elements when the external magnetic field H is not applied to the elements are R1 and R2, the output voltage Vout when the external magnetic field H is not applied (external magnetic field H = 0) is expressed by the following equation (1). expressed.

[0008]

## EQU1 ## Vout = Vin.R2 / (R1 + R2)

On the other hand, when the external magnetic field H is not applied to the magnetic tunnel effect elements having the first area and the second area, the resistance reduction due to the change in the environmental temperature of these elements is represented by ΔR 1 and ΔR 2, respectively. Then, the output voltage Vout is expressed by the following equation (2).

[0010]

Vout = Vin · (R2−ΔR2) / (R1−ΔR1 +
R2-ΔR2)

The structure (material, thickness, etc.) of the TMR element
Are the same, the following equations 3 and 4 hold.

[0012]

[Expression 3] ΔR1 = k · R1

[0013]

## EQU4 ## ΔR2 = kR2

From Equations 3 and 4, Equation 2 can be rewritten as Equation 5 below.

[0015]

Vout = Vin = (R2-kR2) / (R1-k *)
R1 + R2-kR2)

That is, from the above equations (5) and (2), it is understood that even when the environmental temperature changes, the output voltage Vout when the external magnetic field is "0" is Vin · R2 / (R1 + R2) and does not change. You.

Hereinafter, in order to simplify the explanation, the first
And the two magnetic tunnel effect elements are formed such that the magnetization directions of the fixed magnetic layers of the magnetic tunnel effect element having the second area are substantially the same, and the resistance values R1 and R2 are both R0. Consider the case. With respect to such an element, the output out when no external magnetic field H is applied becomes Vin /
2.

Further, when an external magnetic field H having a predetermined magnitude and the same direction as or opposite to the direction of magnetization of the fixed magnetic layer is applied to the magnetic tunnel effect element having the first area, The resistance change from the resistance value R0 is -ΔRd, + ΔRu, respectively, and the external magnetic field H of the same predetermined magnitude, and the magnetic field in the same direction or the opposite direction to the magnetization direction of the fixed magnetization layer has the second area. The resistance change from the resistance value R0 of the element when applied to the magnetic tunnel effect element is-
When Δrd, + Δru, the maximum value Vm of the output voltage Vout
ax and the minimum value Vmin are represented by the following equations (6) and (7).

[0019]

Vmax = Vin · (R0−Δrd) / (R0−ΔRd)
+ R0-Δrd)

[0020]

Vmin = Vin · (R0 + Δru) / (R0 + ΔRd)
+ R0 + Δru)

On the other hand, FIG. 2 shows a magnetic tunnel effect element having the first area (hereinafter simply referred to as the first magnetic tunnel effect) having a predetermined number of magnetic tunnel effect elements each having an area S1 connected in series. And a magnetic tunnel effect element whose individual area is S2 smaller than the area S1 so as to exhibit the same resistance value as that of the first magnetic tunnel effect element. The change characteristics of the resistance value R with respect to the external magnetic field H of the magnetic tunnel effect element having the second area (hereinafter, simply referred to as the second magnetic tunnel effect element) configured by connecting the series connection by the number are represented by line L1. And line L2
Is indicated by.

As understood from FIG. 2, the resistance change Δ
Rd and the resistance change ΔRu are substantially equal, and Δrd and Δru are substantially equal. Therefore, in the following, ΔRd and ΔRu are expressed as ΔRd
(ΔRd = ΔRu = ΔR), Δrd and Δru are defined as Δr (Δrd = Δru = Δr). Further, the sensitivity of the magnetic tunnel effect element is represented by a change amount of the resistance value R with respect to a change amount of the external magnetic field H. Therefore, as understood from FIG.
The change amount of the resistance value of the first magnetic tunnel effect element is ΔRu,
When the external magnetic fields H having the minimum absolute value of ΔRd are the magnetic fields Hu and Hd, respectively, the sensitivity of the second magnetic tunnel effect element is lower than the sensitivity of the first magnetic tunnel effect element at least in the range of the magnetic fields Hu to Hd. Δr is sufficiently smaller than ΔR. From this, the above equations 6 and 7 are rewritten to the following equations 8 and 9, respectively.

[0023]

Vmax = Vin / (2- (ΔR / R0))

[0024]

Vmin = Vin / (2+ (ΔR / R0))

The maximum value Vmax is a value when a magnetic field in the same direction as the magnetization direction of the fixed magnetization layer is applied, and it can be seen from Expression 8 that the maximum value Vmax always exceeds Vin / 2 regardless of the environmental temperature. Further, the minimum value Vmin is a value when a magnetic field in the direction opposite to the magnetization direction of the fixed magnetic layer is applied, and it can be seen from Expression 9 that the minimum value Vmin is always smaller than Vin / 2 regardless of the environmental temperature.

That is, the output Vout of the magnetic sensor of the present invention
Is Vin / when the external magnetic field is "0" regardless of the ambient temperature.
2, which is larger than Vin / 2 when the external magnetic field is in the same direction as the magnetization direction of the fixed magnetic layer, and smaller than Vin / 2 when the external magnetic field is in the opposite direction to the magnetization direction of the fixed magnetic layer. Therefore, according to the present invention, a magnetic sensor having good temperature characteristics capable of reliably detecting the direction of an external magnetic field regardless of the environmental temperature by determining whether or not the output Vout is greater than Vin / 2. Can be provided.

Incidentally, as shown by the broken line in FIG. 1, the voltage across the first magnetic tunnel effect element can be taken out as the output voltage V'out. In this case, the maximum value V'max and the minimum value V'mi of the output voltage V'out
n is a value obtained by subtracting the minimum value Vmin of Equation 9 and the maximum value Vmax of Equation 8 from the voltage Vin of the constant voltage source. Therefore, even when the output is taken out in this way, a magnetic sensor with good temperature characteristics that can reliably detect the direction of the external magnetic field regardless of the environmental temperature can be provided.

Equations (8) and (9) indicate that the external magnetic field varies between Hu and Hd in FIG. 2 and the resistance change Δr of the second magnetic tunnel effect element is the resistance change of the first magnetic tunnel effect element. It is derived on the condition that it is sufficiently small with respect to ΔR. However, when the absolute value of the external magnetic field H increases beyond the range of Hu to Hd, Δr approaches ΔR and cannot be ignored, so as understood from Equations 6 and 7, and as shown in FIG. Output voltage Vout is Vi
n / 2 (hereinafter referred to as “median value”, which is 500 mV in FIG. 3). This output voltage Vout (= Vin / 2)
Is equal to the output voltage Vout when no external magnetic field is applied. In other words, the magnetic sensors having the above characteristics include those which show the same output voltage Vout with respect to external magnetic fields in different directions when the external magnetic field greatly changes from substantially Hu to substantially Hd.

Therefore, in the magnetic sensor characterized by the half bridge circuit, it is preferable that the magnetic tunnel effect element having the second area is magnetically shielded.

According to this, as shown in FIG.
The resistance value of the magnetic tunnel effect element becomes substantially constant irrespective of the change of the external magnetic field, and the resistance change Δr becomes substantially “0”. As a result, even when the external magnetic field changes beyond the range of Hu to Hd, Equations 8 and 9 hold, and as shown in FIG. 5, the output voltage Vout does not approach the median value. It becomes the maximum value Vmax or the minimum value Vmin. That is, the above configuration provides a magnetic sensor that can reliably detect the direction of the external magnetic field regardless of the ambient temperature even under an external magnetic field having a large change width.

Another feature of the present invention is that a direct current voltage source, a fixed magnetization layer whose magnetization direction is fixed to a predetermined direction, a free magnetization layer whose magnetization direction changes according to an external magnetic field, and the fixed magnetization layer And a magnetic tunnel effect element comprising: an insulating layer sandwiched between the free magnetic layers; and a magnetic tunnel effect element having a first area and one end of the magnetic tunnel effect element having a first area. A pair of circuit elements each of which is connected to one end of a tunnel effect element having a second area smaller than the first area, wherein the first element of one of the pair of circuit elements The other end of the magnetic tunnel effect element having an area and the other end of the magnetic tunnel effect element having the second area are respectively connected to the positive electrode and the negative electrode of the DC voltage source, and the other of the pair of circuit elements Circuit elements The other end of the magnetic tunnel effect element having the second area and the other end of the magnetic tunnel effect element having the first area are respectively connected to a positive electrode and a negative electrode of the DC voltage source, and the pair of circuit elements And outputting a potential difference between each connection point of the magnetic tunnel effect element having the first area and the magnetic tunnel effect element having the second area.

Also in this case, the resistance value of the magnetic tunnel effect element having the first area and the resistance value of the magnetic tunnel effect element having the second area may be the same or different. Further, all the magnetic tunnel effect elements may be formed on the same substrate, or each magnetic tunnel effect element may be formed on each independent substrate. The “magnetic tunnel effect element” includes a “magnetic tunnel effect element group in which a plurality of magnetic tunnel effect elements in which the directions of fixed magnetization of the fixed magnetization layers are substantially the same are electrically connected in series”. included.

The above features are schematically shown in FIG. As shown in FIG. 6, when the output voltage of the sensor (that is, the output voltage of the full bridge circuit) is Vout, and other variables are defined in the same manner as shown in FIG. The maximum value Vmax and the minimum value Vmin are represented by the following equations 10 and 11, respectively.

[0034]

Vmax = Vin = (ΔRu−Δru) / (2R0 +
ΔRu + Δru)

[0035]

Vmin = Vin · (Δrd−ΔRd) / (2R0−
ΔRd-Δrd)

As described above, in a magnetic tunnel effect element, ΔRd and ΔRu are generally equal (ΔRd = ΔRd).
Ru = ΔR), Δrd and Δru are equal (Δrd = Δru =
Δr). In the range of the magnetic fields Hu to Hd, Δr
Is sufficiently small with respect to ΔR. From this, the above equation 10
And Equation 11 can be rewritten as Equations 12 and 13, respectively.

[0037]

Vmax = Vin / (1 + 2 · (R0 / ΔR))

[0038]

Vmin = Vin / (1-2 · (R0 / ΔR))

On the other hand, the magnetic tunnel effect element uses the ΔR
Is about one digit smaller than the above R0, so the value R0 / ΔR is 1/2.
Always bigger than. Therefore, according to Equations 12 and 13, the maximum value Vmax and the minimum value Vmin are always positive values, respectively.
It will be a negative value. That is, in this magnetic sensor, the polarity of the output voltage is uniquely determined when the direction of the magnetic field is determined. Therefore, the magnetic sensor having the above configuration is a magnetic sensor that can reliably detect the direction of the magnetic field regardless of changes in the environmental temperature.

The equations (12) and (13) are similar to the equations (8) and (9) in that the external magnetic field is the magnetic field Hu to the magnetic field shown in FIG.
Hd, and is derived based on the condition that the resistance change Δr of the magnetic tunnel effect element having the second area is sufficiently smaller than the resistance change ΔR of the magnetic tunnel effect element having the first area. ing. However, when the absolute value of the external magnetic field increases beyond the range of the magnetic fields Hu to Hd, Δr approaches ΔR, so that Δr cannot be ignored.
As shown in Equations 10 and 11, and FIG. 7, the output voltage V
out approaches "0". On the other hand, the value of the output voltage Vout when no external magnetic field is applied is also “0”. That is, the magnetic sensors having the above characteristics include ones that show the same output voltage Vout for different directions of the external magnetic field when the external magnetic field largely changes from substantially Hu to substantially Hd.

Therefore, in the magnetic sensor characterized by the full bridge circuit, it is preferable to magnetically shield the magnetic tunnel effect element having the second area.

According to this, as shown in FIG.
The resistance value of the magnetic tunnel effect element becomes substantially constant irrespective of the change of the external magnetic field, and the resistance change Δr becomes substantially “0”. As a result, even when the external magnetic field changes beyond the range of Hu to Hd, Equations 12 and 13 hold, and the output voltage Vout does not approach “0” as shown in FIG. It becomes the maximum value Vmax or the minimum value Vmin. That is, the above configuration provides a magnetic sensor that functions effectively even under an external magnetic field having a large change width.

[0043]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, first to fourth embodiments of a magnetic sensor using a magnetic tunnel effect element according to the present invention will be described first from the structure of a magnetic tunnel effect element commonly used in each embodiment. I do. FIG. 9 is a schematic sectional view showing a part of such a magnetic tunnel effect element, and FIGS. 10 and 11 are schematic plan views of the magnetic tunnel effect element corresponding to FIG.

The magnetic tunnel effect element is made of, for example, Si
A substrate 10 made of O ₂ / Si, glass or quartz is provided. On the substrate 10, a plurality of lower electrodes 11 having a rectangular planar shape are arranged in a row at predetermined intervals in a horizontal direction, and the lower electrodes 11 are made of a conductive non-magnetic metal material of Cr ( Or, it is formed to a thickness of about 30 nm by Ti). On each lower electrode 11, the lower electrode 11 is formed in the same plane shape as that of the lower electrode 11, and is made of PtMn and has a thickness of 50n.
About m of antiferromagnetic films 12 are stacked. The anti-anti-ferromagnetic film 12 is magnetized in the direction of the arrow (left direction) in FIG.

On each antiferromagnetic film 12, a pair of ferromagnetic films 13, 13 made of NiFe and having a thickness of about 10 nm are laminated at intervals. The ferromagnetic films 13, 13
It has a rectangular shape in plan view, and is arranged such that each long side faces in parallel. The ferromagnetic film 13 constitutes a fixed magnetic layer (fixed layer) which is a hard magnetic film in which the direction of magnetization is fixed in cooperation with the antiferromagnetic film 12. (Right).

On each ferromagnetic film 13, the same ferromagnetic film 13
An insulating layer 14 having the same planar shape as that of FIG.
This insulating layer 14 is made of Al ₂ O ₃ (Al-
O) and has a thickness of about 2 to 4 nm.

On the insulating layer 14, a ferromagnetic film 15 made of NiFe having the same planar shape as the insulating layer 14 and a thickness of about 40 nm is formed. This ferromagnetic film 15
A free magnetic layer, which is a soft magnetic magnetic film whose magnetization direction changes in accordance with the direction of an external magnetic field, is formed.
A magnetic tunnel junction structure is formed together with the fixed magnetic layers 2 and 13 and the insulating layer 14.

On each ferromagnetic film 15, each ferromagnetic film 1
Dummy films 16 having the same planar shape as 5 are formed. The dummy film 16 is made of a conductive non-magnetic metal material made of a Mo film having a thickness of about 40 nm.

Substrate 10, lower electrode 11, antiferromagnetic film 1
2. In a region covering the ferromagnetic film 13, the insulating layer 14, the ferromagnetic film 15 and the dummy film 16, the plurality of lower electrodes 11 and the antiferromagnetic film 12 are insulated and separated from each other. , A pair of ferromagnetic films 13, an insulating layer 14,
An interlayer insulating layer 17 for insulating the ferromagnetic film 15 and the dummy film 16 from each other is provided. Interlayer insulating layer 1
7 is made of, for example, SiO ₂ and has a thickness of 250 nm.
It is about.

Each dummy film 16 is formed on the interlayer insulating film 17.
Above, contact holes 17a are respectively formed. While burying this contact hole 17a,
Upper electrodes 18 made of, for example, 300 nm-thickness Al are respectively connected so as to electrically connect one of the pair of dummy films 16 provided on the different lower electrode 11 and antiferromagnetic film 12 to each other. Is formed. Thus, the lower electrode 11 and the antiferromagnetic film 12 and the upper electrode 18
Thus, the ferromagnetic films 15 and 15 (dummy films 16 and 16) and the antiferromagnetic films 12 and 12 of the pair of magnetic tunnel junctions adjacent to each other are electrically connected alternately and sequentially and fixed. A magnetic tunnel effect element (magnetic tunnel effect element group) in which the magnetization directions of the magnetization layers are the same and a plurality of magnetic tunnel junction structures are connected in series is formed.

Note that one lower electrode 11 and antiferromagnetic film 12 and a pair of magnetic tunnel effect elements formed thereon (each pair of ferromagnetic films 13 and 13 and insulating layers 14 and 1).
4, a pair of the above-described rectangular magnetic tunnel effect elements having the ferromagnetic films 15, 15 and the dummy films 16, 16) is hereinafter referred to as a “one set of magnetic tunnel effect elements”.

Here, the relationship between the sensitivity of the magnetic tunnel effect element and the area (the area of the insulating layer 14 and the ferromagnetic film 15 as the free magnetic layer in plan view) will be described. The sensitivity of the magnetic tunnel effect element is represented by the change in the resistance value R of the element with respect to the change in the external magnetic field H. Therefore, as shown in FIG. 12, when the characteristic curve of the magnetic tunnel effect element is shown on a graph where the horizontal axis and the vertical axis are the external magnetic field H and the resistance value R, respectively, the sensitivity of the element is expressed by the slope θ of the curve. Will be done. In this case, the larger the inclination θ, the better the sensitivity.

On the other hand, the resistance value R of the magnetic tunnel effect element
When a positive external magnetic field and a negative external magnetic field whose absolute values are equal to each other are applied, the resistance changes when the external magnetic field is not applied (external magnetic field H = “0”) by substantially the same resistance. Further, when the material of each layer constituting the magnetic tunnel effect element is determined, the maximum change amount ΔRmax (= Rmax−Rmin) of the resistance value R due to the magnetic field change is uniquely determined. Therefore, if the magnetic field Hs at which the resistance value reaches the maximum value Rmax, that is, the saturation magnetic field Hs is determined, the slope θ of the characteristic curve is determined. That is,
The saturation magnetic field Hs indicates the sensitivity of the magnetic tunnel effect element, and the smaller the saturation magnetic field Hs, the better the sensitivity of the magnetic tunnel effect element.

Therefore, in order to know the relationship between the sensitivity and the area of the magnetic tunnel effect element, the saturation magnetic fields Hs of a plurality of types of magnetic tunnel effect elements having different areas were measured. For the measurement, as shown in FIG. 13, a rectangular shape having a long side L × short side (width) W and an aspect ratio of “6” or “3” was used. The aspect ratio is a ratio (L / W) of the long side L to the short side W.

As is apparent from FIG. 14 showing the measurement results, the saturation magnetic field Hs of the magnetic tunnel effect element increased as the area S of the element decreased (as the width W decreased). In other words, the sensitivity of the magnetic tunnel effect element is equal to the area S
It was found that the lower the width (in particular, the width W), the lower.

Next, each embodiment of the magnetic sensor with improved temperature characteristics according to the present invention will be described individually.

(First Embodiment) A magnetic sensor according to a first embodiment conceptually shown in FIG. 1 includes a first magnetic tunnel effect element (group) 31 and a second magnetic tunnel effect element (group) 3.
2 and a DC constant voltage source 33 whose generated voltage is Vin. The first magnetic tunnel effect element 31 and the second magnetic tunnel effect element 32 are connected in series to the DC constant voltage It is constituted by a half bridge circuit for taking out the voltage between both ends of the tunnel effect element 32 as an output voltage Vout.

The first magnetic tunnel effect element 31 corresponds to FIG.
As shown in FIG. 9, a pair of first magnetic tunnel effect elements 31b is formed on a single substrate 31a corresponding to the substrate 10 of FIG.
They are arranged in a matrix of 0 rows × 11 columns. The short side and the long side of each of the pair of first magnetic tunnel effect elements 31b are aligned in the row direction (the horizontal direction in FIG. 15) and the column direction (FIG. 1).
5 (in the vertical direction), and the magnetization directions of the fixed magnetic layer are all the same (here, FIG. 15).
Left and right).

A set of these magnetic tunnel effect elements 31
b is electrically connected in series and formed to have one resistance value (about 3 kΩ in this example). That is, for the elements except for the set of magnetic tunnel effect elements 31b located at the ends in the row direction (left-right direction), each ferromagnetic film 15,
15 (each dummy film 16, 16) are connected with the upper electrode 18 by the structure described in FIG. 9. Regarding the set of magnetic tunnel effect elements 31b located at the end in the row direction, each ferromagnetic film 15, 15 on the end side of the set of magnetic tunnel effect elements 31b adjacent in the column direction (vertical direction).
These are connected by the upper electrode 18 with a structure similar to the structure described in FIG. A set of magnetic tunnel effect elements 31b located at the upper right end in FIG.
The right ferromagnetic film 15 is connected to the positive electrode side of the DC constant voltage source 33, and the right ferromagnetic film 15 of the pair of magnetic tunnel effect elements 31b located at the lower right end is the second magnetic tunnel effect element. It is connected to the ferromagnetic film 15 on the right side of a pair of magnetic tunnel effect elements 32b located at the upper right end of the reference numeral 32.

FIG. 16 is a schematic plan view showing the size of a set of first magnetic tunnel effect elements 31b.
The lower electrode 31c and the antiferromagnetic film 31d respectively corresponding to the lower electrode 11 and the antiferromagnetic film 12 shown in FIG. 9 have a short side × long side of 52 μm × 68 μm. Also, the ferromagnetic films 31e and 31e formed on the antiferromagnetic film 31d and corresponding to the ferromagnetic film 15 of FIG.
The short side x long side of e is 20 μm × 60 μm.
Therefore, the area S1 of one magnetic tunnel effect element in plan view is 1.20 × 10 ⁻⁹ m ² . Peripheral portion of each ferromagnetic film 31e, lower electrode 31c and antiferromagnetic film 31d
Is separated by 4 μm from the periphery of the pair of ferromagnetic films 31.
e and 31e are also formed so as to be separated by 4 μm.

FIG. 17 shows the temperature characteristics of the first magnetic tunnel effect element 31 constructed as described above. Lines A, B and C change the ambient temperature to 25, 90 and 150 ° C., respectively. 3 shows a change in resistance value of the same sample with respect to an external magnetic field in the case where. As can be understood from FIG. 17, even when the external magnetic field is in the opposite direction, the resistance indicated by the sample may be the same depending on the environmental temperature. It is difficult to use it as a magnetic sensor for detecting the direction.

The second magnetic tunnel effect element 32 corresponds to FIG.
As shown in FIG. 9, a pair of rectangular second magnetic tunnel effect elements 32b are arranged in a matrix of 2 rows × 11 columns on a single substrate 32a corresponding to the substrate 10 shown in FIG. is there. Each set of first magnetic tunnel effect elements 32b
Are formed along the row direction (horizontal direction in FIG. 15) and the column direction (vertical direction in FIG. 15), and the magnetization directions of the fixed magnetic layers are all the first magnetic field. The tunnel effect element 31 is formed so as to be in the same direction as the magnetization direction of each fixed magnetization layer.

The set of second magnetic tunnel effect elements 32 b is formed of the first magnetic tunnel effect element 31
Like the magnetic tunnel effect element 31b, they are electrically connected in series, and the resistance of the second magnetic tunnel effect element 32 and the first
The resistance value of the magnetic tunnel effect element 31 is the same. That is, for the elements other than the pair of magnetic tunnel effect elements 32b located at the ends in the row direction, the ferromagnetic films 15 of the pair of magnetic tunnel effect elements 32b adjacent in the row direction,
15 (each dummy film 16, 16) are connected with the upper electrode 18 by the structure described in FIG. 9. A set of magnetic tunnel effect elements 32b located at the left end in the row direction
For each of the ferromagnetic films 1 on the left side of the pair of magnetic tunnel effect elements 32b located at the row direction ends of the first row and the second row.
The upper and lower electrodes 5 and 15 are connected to each other by a structure similar to the structure described with reference to FIG. FIG.
, The ferromagnetic film 15 on the right side of the pair of magnetic tunnel effect elements 32b located at the lower right end is connected to the negative electrode side of the DC constant voltage source 33.

FIG. 18 is a schematic plan view showing the size of a set of second magnetic tunnel effect elements 32b.
The lower electrode 32c and the antiferromagnetic film 32d respectively corresponding to the lower electrode 11 and the antiferromagnetic film 12 shown in FIG. 9 have a short side × long side of 24 μm × 48 μm. The short side x long side of each ferromagnetic film 32e corresponding to the ferromagnetic film 15 of FIG. 9 formed on the lower electrode 32c and the antiferromagnetic film 32d is 6 μm × 40 μm. Accordingly, the area S2 of one magnetic tunnel effect element constituting the set of second magnetic tunnel effect elements 32b in plan view
Is 0.24 × 10 ⁻⁹ m ² . Each ferromagnetic film 3
2e, lower electrode 32c and antiferromagnetic film 32d
A distance of 4 μm from the periphery of the pair of ferromagnetic films 32.
e and 32e are also formed to be separated by 4 μm.

As described above, the area S2 of one element of the set of second magnetic tunnel effect elements 32b is one of the area S1 of one element of the set of first magnetic tunnel effect elements 31b.
/ 5. Therefore, when no external magnetic field is applied, the resistance value of one element of the set of second magnetic tunnel effect elements 32b becomes one set of the first magnetic tunnel effect element 31b.
It becomes five times the resistance value of one element of b. For this reason, the resistance value of the first magnetic tunnel effect element 31 in which a total of 110 (= 10 × 11) sets of the first magnetic tunnel effect elements 31b are connected in series, and the set of the first magnetic tunnel effect elements 32b Are equal to the resistance value of the second magnetic tunnel effect element 32 in which a total of 22 (= 2 × 11) are connected in series.
0 = 3 (kΩ).

Next, the characteristics of the magnetic sensor thus configured will be described. Now, the voltage of the DC voltage source is Vin,
Assuming that the resistance value of both elements when no external magnetic field H is applied to the first and second magnetic tunnel effect elements 31 and 32 is R0, when the external magnetic field H is not applied (external magnetic field H = 0). The output voltage Vout is Vout = Vin / 2. This is true regardless of the ambient temperature.

FIG. 2 shows changes in the resistance value R of the first magnetic tunnel effect element 31 and the second magnetic tunnel effect element 32 with respect to the external magnetic field H by curves L1 and L2, respectively. In FIG. 2, the external magnetic field H having a positive value depends on its direction and the first and second magnetic tunnel effect elements 3.
The external magnetic field H having a negative value is a magnetic field in which the magnetization directions of the fixed magnetization layers of the first and second fixed magnetic layers 31 and 32 are fixed. This is a magnetic field in which the direction of magnetization differs by 180 ° (that is, a magnetic field in the opposite direction).

As is clear from FIG. 2, the resistance value of the first magnetic tunnel effect element 31 becomes the resistance value R0 when no external magnetic field H is applied (H = 0 (Oe)). The maximum value Rmax (= R0 + ΔRu) and the minimum value Rmin (= R0) in a region equal to or smaller than Hu (Hu ≒ −20 (Oe)) and a region equal to or larger than the magnetic field Hd (Hd ≒ 20 (Oe)).
−ΔRd).

On the other hand, when the external magnetic field H is not applied, the resistance value of the second magnetic tunnel effect element 32 is equal to the resistance value R0,
When the external magnetic field H is the magnetic field Hu and the magnetic field Hd, the value R0
+ Δru and values R0−Δrd, positive and negative magnetic fields having absolute values sufficiently larger than the absolute values of the magnetic fields Hu and Hd (in this example, approximately ±
90 (Oe)) are the maximum value Rmax and the minimum value Rmin, respectively. Therefore, the maximum value Vmax of the output voltage Vout of the magnetic sensor including the half bridge circuit is as follows: Vmax = Vin · (R0−Δrd) / (R0)
−ΔRd + R0−Δrd) (Equation 6) and the minimum value Vmin
Is as follows: Vmin = Vin · (R0 + Δru) / (R0 + ΔRd + R0)
+ Δru) (Equation 7). In this case, ΔRd and ΔRu
Are approximately equal, so this can be placed as ΔR. Similarly, since Δrd and Δru are substantially equal, this can be set as Δr.

By the way, as described above, the sensitivity (maximum sensitivity) of the magnetic tunnel effect element decreases as the area S of the element decreases. This is the same in the measurement example shown in FIG. 2. The sensitivity of the second magnetic tunnel effect element 32 is lower than the sensitivity of the first magnetic tunnel effect element 31,
r becomes sufficiently smaller than ΔR. Therefore, from the above equations (1) and (2), Vmax = Vin / (2- (ΔR / R0))
(Equation 8), the minimum value Vmin is Vmin = Vin / (2+ (ΔR
/ R0)) (Equation 9) is derived. According to Equations 8 and 9, it is understood that the maximum value Vmax and the minimum value Vmin change with ΔR / R0.

In this case, the maximum value Vmax is a value when a magnetic field having the same direction as the magnetization direction of the fixed magnetization layer is applied, and it can be seen from Expression 8 that the maximum value Vmax is always larger than Vin / 2 regardless of the environmental temperature. . Further, the minimum value Vmin is a value when a magnetic field in the direction opposite to the magnetization direction of the fixed magnetic layer is applied, and it can be seen from Expression 9 that the minimum value Vmin is always smaller than Vin / 2 regardless of the environmental temperature.

As described above, in the magnetic sensor according to the first embodiment, the external magnetic field is Vin / 2 when the external magnetic field is “0” regardless of the environmental temperature, and the external magnetic field is the same as the magnetization direction of the fixed magnetic layer. In the case of the direction, it is larger than Vin / 2, and when the external magnetic field is in the direction opposite to the direction of magnetization of the fixed magnetic layer, it becomes smaller than Vin / 2. That is, the magnetic sensor according to the first embodiment includes:
By determining whether or not the output Vout is greater than Vin / 2, the direction of the external magnetic field can be reliably detected regardless of the environmental temperature.

FIG. 3 shows an example of the result of measuring the output characteristics of such a magnetic sensor at room temperature. From FIG. 3, as long as the external magnetic field changes in the range of approximately Hu to approximately Hd, It is confirmed that the magnetic sensor is a magnetic sensor with very good sensitivity.

As shown by the broken lines in FIGS. 1 and 15, the voltage across the magnetic tunnel effect element 31 having the first area can be taken out as the output voltage V'out. In this case, the maximum value V'max and the minimum value V'min of the output voltage V'out are calculated from the voltage Vin of the DC constant voltage source 33 by the minimum value Vmin of Equation 9 and the maximum value Vm of Equation 8 above.
ax is subtracted from each other. Therefore, even when the output is taken out in this way, the maximum value V'max and the minimum value V'min do not become the same regardless of the environmental temperature, and the direction of the external magnetic field is ensured regardless of the environmental temperature. Can be detected.

(Embodiment 2) Equations (8) and (9) indicate that the external magnetic field H changes in the magnetic fields Hu to Hd (within the range of the saturation magnetic field Hs) shown in FIG. It is derived based on a condition that the resistance change Δr is sufficiently smaller than the resistance change ΔR of the first magnetic tunnel effect element 31. However, the absolute value of the external magnetic field H is
If it becomes larger than the range of Hd, Δr approaches ΔR and cannot be ignored. Therefore, as can be understood from Equations 6 and 7, when the absolute value of the external magnetic field H applied to the element increases, both the maximum value Vmax and the minimum value Vmin of the output voltage Vout approach Vin / 2. This output voltage Vout (=
Vin / 2) is equal to the output voltage Vout when no external magnetic field is applied. FIG. 3 shows an actual measurement result.
In the case where the external magnetic field H is “0” and the case where the absolute value of the external magnetic field H is sufficiently large, the output voltage Vou
Both t became 500 mV.

This means that the magnetic sensor according to the first embodiment functions as a high-sensitivity magnetic sensor when the external magnetic field changes between Hu and Hd.
If it changes beyond, it means that it may not be suitable as a magnetic sensor.

The second embodiment is to solve such a disadvantage of the first embodiment, and as shown in FIG. 19, the second magnetic tunnel effect element 32 of the first embodiment is used.
Is covered with a soft magnetic material 32f made of, for example, NiFe (Ni: Fe = 81: 19), and thus the second magnetic tunnel effect element 32 is magnetically shielded from the first embodiment.

As described above, the sensitivity of the second magnetic tunnel effect element 32 is lower than that of the first magnetic tunnel effect element 31, and the resistance value R hardly changes in response to a change in the external magnetic field. Therefore, the resistance value of the second magnetic tunnel effect element 32 hardly changes with respect to the external magnetic field H due to further magnetic shielding. When the characteristics of the magnetically shielded second magnetic tunnel effect element 32 are actually measured, as shown in FIG. 4, the resistance value R becomes substantially constant without being affected by the external magnetic field H. I was

Therefore, in the magnetic sensor configured as described above, even when the external magnetic field H changes in a wider range than the magnetic fields Hu to Hd, the above Expressions 8 and 9 hold. That is, the output voltage Vout takes the maximum value Vmax and the minimum value Vmin in the vicinity of the magnetic fields Hu to Hd, respectively, and even when the external magnetic field H having an absolute value larger than the maximum value is applied, the median value Vin is obtained.
/ 2 is maintained, and the maximum value Vmax and the minimum value Vmin are maintained. This is confirmed by FIG. 5 showing the result of measuring the output voltage Vout of the magnetic sensor according to the second embodiment at normal temperature (25 ° C.).

As described above, even when the magnetic sensor according to the second embodiment is used under the external magnetic field H which greatly changes beyond the magnetic fields Hu to Hd, the magnetic sensor according to the second embodiment does The magnetic sensor according to the first embodiment has good characteristics without exhibiting the same output voltage Vout, and has good temperature characteristics for the same reason as the magnetic sensor of the first embodiment.

(Third Embodiment) Next, a magnetic sensor according to a third embodiment conceptually shown in FIG. 6 will be described.
This magnetic sensor includes first magnetic tunnel effect elements 41 and 42 configured similarly to the first magnetic tunnel effect element 31.
And second magnetic tunnel effect elements 43 and 44 configured similarly to the second magnetic tunnel effect element 32, and a DC constant voltage source 45. Magnetic tunnel effect elements 41 to 44
Are formed such that the fixed magnetization directions of the fixed magnetic layer are all substantially the same.

In this magnetic sensor, one end of the first magnetic tunnel effect element 41 and the second magnetic tunnel effect element 4
3 are connected to one end to form one circuit element.
Another circuit element in which one end of the magnetic tunnel effect element 44 and one end of the first magnetic tunnel effect element 42 are connected is formed, and the other end of the first magnetic tunnel effect element 41 and the other The ends are connected to the positive and negative electrodes of the DC constant voltage source 45, respectively, and the other end of the second magnetic tunnel effect element 44 and the other end of the first magnetic tunnel effect element 42 are connected to the positive and negative electrodes of the DC constant voltage source 45, respectively. These are connected to each other to form a full bridge circuit. And
The potential at the connection point between the first magnetic tunnel effect element 41 and the second magnetic tunnel effect element 43 and the potential at the connection point between the second magnetic tunnel effect element 44 and the first magnetic tunnel effect element 42 are taken out. The configuration is such that the potential difference between these connection points becomes the output voltage Vout.

FIG. 20 is a schematic plan view of this magnetic sensor. The first magnetic tunnel effect elements 41 and 42 have the same configuration as the above-described first magnetic tunnel effect element 31, and each of the substrates 41a and 42a Have a set of magnetic tunnel effect elements 41b and 42b, which are formed in a matrix of 10 rows × 11 columns and electrically connected in series. One set of magnetic tunnel effect elements 41b, 4
Each structure and size of the magnetic tunnel effect element 3b described with reference to FIGS. 9 to 11 and FIG.
Same as 1b.

The second magnetic tunnel effect elements 43 and 44 are
It is configured similarly to the above-described second magnetic tunnel effect element 32, is formed in a matrix of 2 rows × 11 columns on the upper surface of each of the substrates 43a and 44a, and is a set of magnetic elements electrically connected in series. It has tunnel effect elements 43b and 44b, respectively. One set of magnetic tunnel effect element 43
b and 44b are shown in FIGS.
1 and a set of the magnetic tunnel effect element 32b described with reference to FIG.

Next, the characteristics of the magnetic sensor according to the third embodiment will be described. The maximum value Vmax of the output voltage Vout of the magnetic sensor is as follows: Vmax = Vi
n · (ΔRu−Δru) / (2R0 + ΔRu + Δru) (Equation 10), and for the minimum value Vmin, Vmin = Vin · (Δrd)
−ΔRd) / (2R0−ΔRd−Δrd) (Equation 11) is established. Further, as described above, ΔRd and Δrd in Equations 10 and 11 can be set equal to ΔR, and ΔRu and Δru can be set equal to Δr. Further, when the external magnetic field H is in the range of the magnetic fields Hu to Hd,
The Δr can be treated as sufficiently smaller than the ΔR. Therefore, from the above equation 10, Vmax = Vin / (1
+ 2 · (R0 / ΔR)) (Equation 12) From the above Equation 11, Vmin = Vin / (1-2 · (R0 / ΔR)) (Equation 13)
Is derived.

On the other hand, the magnetic tunnel effect element uses the ΔR
Is about one digit smaller than the above R0, so the value R0 / ΔR is 1/2.
Always bigger than. Therefore, according to Equations 12 and 13, the maximum value Vmax and the minimum value Vmin are always positive values, respectively.
It will be a negative value. That is, in this magnetic sensor, the polarity of the output voltage is uniquely determined when the direction of the magnetic field is determined. Therefore, the magnetic sensor having the above-described configuration is a magnetic sensor that can reliably detect the direction of the external magnetic field irrespective of changes in the environmental temperature.

As described above, the magnetic sensor according to the third embodiment has good temperature characteristics. FIG.
FIG. 7 shows an example of the result of measuring the output voltage Vout of this magnetic sensor at room temperature. From FIG. 7, as long as the external magnetic field changes in a range of approximately Hu to approximately Hd, the magnetic sensor has a high sensitivity. It was confirmed that it was a very good magnetic sensor.

(Fourth Embodiment) The above equations (12) and (13) are
The external magnetic field changes between the magnetic fields Hu to Hd shown in FIG. 2 and the resistance change Δr of the second magnetic tunnel effect elements 43 and 44.
Is derived on the condition that the resistance change ΔR of the first magnetic tunnel effect elements 41 and 42 is sufficiently small. However, the absolute value of the external magnetic field H is
If it becomes larger than the range of Hd, Δr approaches ΔR and cannot be ignored. Therefore, the above equations (10) and (11)
As can be understood from the above, when the absolute value of the external magnetic field H applied to the element increases, both the maximum value Vmax and the minimum value Vmin of the output voltage Vout approach "0". On the other hand, the value of the output voltage Vout when no external magnetic field is applied is also “0”.
This is also observed in FIG. 7 showing the actual measurement results, and the output voltage Vout gradually approaches “0” as the absolute value of the external magnetic field H increases.

This means that the magnetic sensor according to the third embodiment functions as a high-sensitivity magnetic sensor when the external magnetic field changes between Hu and Hd.
If it changes beyond, it means that it may not be suitable as a magnetic sensor.

The fourth embodiment is to solve such a disadvantage of the third embodiment, and as shown in FIG. 21, the second magnetic tunnel effect element 43, 43 of the third embodiment is used.
44 is coated with soft magnetic bodies 43c and 44c made of, for example, NiFe (Ni: Fe = 81: 19),
This is different from the third embodiment only in that the second magnetic tunnel effect elements 43 and 44 are magnetically shielded.

When the magnetic shielding is applied to the second magnetic tunnel effect elements 43 and 44 whose sensitivity has been reduced by reducing the area S (width W), the case where the magnetic shielding is applied to the second magnetic tunnel effect element 32 is different from the case where the magnetic shielding is applied to the second magnetic tunnel effect element 32. Similarly, the resistance value hardly changes with a change in the external magnetic field H. As a result, even when the external magnetic field H changes in a wider range than the magnetic fields Hu to Hd,
Equations (12) and (13) hold, and the output voltage V
out does not approach "0" and maintains the maximum value Vmax or the minimum value Vmin even when the external magnetic field H changes beyond the magnetic fields Hu to Hd. This was also confirmed from FIG. 8 showing the result of measuring the output voltage Vout of the magnetic sensor according to the fourth embodiment at normal temperature.

As described above, in the magnetic sensor according to the fourth embodiment, the external magnetic field H that greatly changes beyond the magnetic fields Hu to Hd is used.
Even when the magnetic sensor is used under the following conditions, it has good characteristics that it does not exhibit the same output voltage Vout with respect to different external magnetic fields H, and has the same temperature characteristics as the magnetic sensor of the third embodiment. Is good.

As described above, each embodiment of the magnetic sensor according to the present invention has improved temperature characteristics as compared with the case where the resistance value of the magnetic tunnel effect element itself is detected. Further, the magnetic sensors according to the first and third embodiments include:
Unlike the magnetic sensors of the second and fourth embodiments, magnetic shielding is not required, so that a magnetic shielding step generally performed by a plating step can be omitted, and the manufacturing process can be simplified.

The present invention is not limited to the above embodiment, and various modifications can be adopted within the scope of the present invention. For example, in each of the above embodiments, the first magnetic tunnel effect element 31 (41, 42)
Although the second magnetic tunnel effect element 32 (43, 44) is formed on a separate substrate, they may be formed on the same substrate. In the first to fourth embodiments, each magnetic tunnel effect element may be provided as shown in FIGS. Further, although an antiferromagnetic film made of PtMn is used for the fixed magnetic layer in each of the above embodiments, this is replaced with a CoCr-based metal (for example, CoPt).
It can be replaced with a ferromagnetic film such as Cr).

[Brief description of the drawings]

FIG. 1 is a conceptual plan view of a magnetic sensor according to a first embodiment of the present invention.

FIG. 2 is a graph showing a change in resistance value with respect to an external magnetic field for each magnetic tunnel effect element having a different area shown in FIG.

FIG. 3 is a graph showing a change in an output voltage with respect to an external magnetic field of the magnetic sensor according to the first embodiment of the present invention.

FIG. 4 is a graph showing a change in resistance value of a magnetically shielded magnetic tunnel effect element used in a second embodiment of the present invention with respect to an external magnetic field.

FIG. 5 is a graph showing a change in an output voltage with respect to an external magnetic field of a magnetic sensor according to a second embodiment of the present invention.

FIG. 6 is a conceptual plan view of a magnetic sensor according to a third embodiment of the present invention.

FIG. 7 is a graph showing a change in output voltage with respect to an external magnetic field of a magnetic sensor according to a third embodiment of the present invention.

FIG. 8 is a graph showing a change in output voltage with respect to an external magnetic field of a magnetic sensor according to a fourth embodiment of the present invention.

FIG. 9 is a schematic sectional view showing a part of a magnetic tunnel effect element used in the magnetic sensor according to each embodiment of the present invention.

10 is a schematic plan view of the magnetic tunnel effect element shown in FIG. 9 from which an interlayer insulating film and a substrate are omitted.

11 is a schematic plan view of an antiferromagnetic film forming a fixed magnetization layer of the magnetic tunnel effect element shown in FIG.

FIG. 12 is a graph schematically showing a change in resistance value of the magnetic tunnel effect element with respect to an external magnetic field in order to explain the relationship between the sensitivity of the magnetic tunnel effect element and a saturation magnetic field.

FIG. 13 is a plan view of a free magnetic layer of the magnetic tunnel effect element for explaining the size of the element.

FIG. 14 is a graph showing the results of measuring the saturation magnetic field with respect to the width of the magnetic tunnel effect element.

FIG. 15 is a schematic plan view of the magnetic sensor according to the first embodiment of the present invention.

FIG. 16 is a plan view of a substrate (fixed magnetic layer) and a free magnetic layer of the first magnetic tunnel effect element shown in FIG. 15 for describing the size of the element.

17 is a first magnetic tunnel effect element (a magnetic tunnel effect element having a first area) shown in FIGS. 1 and 15;
FIG. 7 is a diagram showing a change in resistance value with respect to an external magnetic field for each environmental temperature.

18 is a plan view of a substrate (fixed magnetic layer) and a free magnetic layer of the second magnetic tunnel effect element shown in FIG. 15 for describing the size of the element.

FIG. 19 is a schematic plan view of a magnetic sensor according to a second embodiment of the present invention.

FIG. 20 is a schematic plan view of a magnetic sensor according to a third embodiment of the present invention.

FIG. 21 is a schematic plan view of a magnetic sensor according to a fourth embodiment of the present invention.

FIG. 22 is a schematic plan view of a magnetic sensor according to a modification of the first embodiment of the present invention.

FIG. 23 is a schematic plan view of a magnetic sensor according to a modification of the second embodiment of the present invention.

FIG. 24 is a schematic plan view of a magnetic sensor according to a modification of the third embodiment of the present invention.

FIG. 25 is a schematic plan view of a magnetic sensor according to a modification of the fourth embodiment of the present invention.

[Explanation of symbols]

11 lower electrode, 12 antiferromagnetic film, 13 ferromagnetic film,
14 ... insulating layer, 15 ... ferromagnetic film, 16 ... dummy film, 17
... interlayer insulating layer, 18 ... upper electrode, 31 ... first magnetic tunnel effect element, 31a ... substrate, 31b ... one set of first magnetic tunnel effect element, 31c ... lower electrode, 31d ... antiferromagnetic film, 31e ... strong Magnetic film, 32: second magnetic tunnel effect element, 32a: substrate, 32b: one set of second magnetic tunnel effect element, 32c: lower electrode, 32d: antiferromagnetic film, 32
e: ferromagnetic film, 32f: soft magnetic material, 33: DC constant voltage source, 41, 42: first magnetic tunnel effect element, 41a,
42a: substrate; 41b, 42b: a set of first magnetic tunnel effect elements; 43, 44: second magnetic tunnel effect elements;
43a, 44a ... substrate, 43b, 44b ... one set of second magnetic tunnel effect elements, 43c, 44c ... soft magnetic material, 45
... DC constant voltage source.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2G017 AA03 AB05 AC04 AD55 AD65 5D034 BA02 BB02 BB14 CA03 5D091 DD03 HH11 5E049 AA01 AA07 AA09 AC05 BA16 CB02

Claims (4)

[Claims] A DC voltage source; a fixed magnetic layer having a fixed magnetization direction fixed to a predetermined direction; a free magnetic layer having a magnetization direction changed in accordance with an external magnetic field; A magnetic tunnel effect element including an insulating layer sandwiched between the magnetic tunnel effect element, the magnetic tunnel effect element having a first area, and the magnetic tunnel effect element. A device having a second area smaller than the first area is connected in series to the DC voltage source to output a voltage across either of the magnetic tunnel effect devices. A magnetic sensor comprising: 2. The magnetic sensor according to claim 1, wherein the magnetic tunnel effect element having the second area is magnetically shielded. 3. A DC voltage source, a fixed magnetic layer whose magnetization direction is fixed to a predetermined direction, a free magnetic layer whose magnetization direction changes in accordance with an external magnetic field, a fixed magnetic layer, and a fixed magnetic layer. A magnetic tunnel effect element including an insulating layer sandwiched between the magnetic tunnel effect element, the magnetic tunnel effect element having one end having a first area and the magnetic tunnel effect element. A pair of circuit elements each having a second area smaller than the first area and connected to one end thereof, and a magnetic tunnel effect having the first area of one circuit element of the pair of circuit elements The other end of the element and the other end of the magnetic tunnel effect element having the second area are connected to a positive electrode and a negative electrode of the DC voltage source, respectively, and Has an area of 2 The other end of the magnetic tunnel effect element and the other end of the magnetic tunnel effect element having the first area are connected to the positive electrode and the negative electrode of the DC voltage source, respectively, and the first area of the pair of circuit elements is connected. A magnetic tunnel effect element configured to output a potential difference between connection points of the magnetic tunnel effect element having the second area and the magnetic tunnel effect element having the second area. 4. The magnetic sensor according to claim 3, wherein the magnetic tunnel effect element having the second area is magnetically shielded.