Magnetic sensor and mfg method, magnet array adapted to said method

Magnetic sensor, manufacturing method thereof, and magnet array suitable for manufacturing method

Technical field

The present invention relates to a magnetic sensor using a magnetoresistance effect element composed of a pinned layer and a free layer, a manufacturing method of the magnetic sensor, and a magnet array suitable for the manufacturing method.

Background technique

Until now, magnetoresistive effect elements such as large magnetoresistive elements (GMR elements) have been used in magnetic sensors. The large magnetoresistive elements have a pinned layer whose magnetization direction is pinned (fixed) in a predetermined direction. The free layer whose magnetization direction changes according to an external magnetic field exhibits a resistance value corresponding to the relative relationship between the magnetization direction of the pinned layer and the magnetization direction of the free layer. In such a magnetic sensor, in order to detect a small external magnetic field with high accuracy, it is necessary to stably maintain the magnetization direction of each magnetic region of the free layer when the external magnetic field is not applied to the magnetic sensor in a predetermined direction (hereinafter, the The prescribed direction is called the "direction of the initial state").

Therefore, generally, when the horizontal view shape of the free layer of the film is rectangular, the long side (long axis) of the rectangle is aligned with the direction of the initial state, so that the magnetization direction is aligned with the longitudinal direction. The shape anisotropy makes the magnetization direction of each magnetic region of the free layer coincide with the direction of the initial state. In addition, a permanent magnetic film, that is, a biasing film is arranged at both ends of the free layer in the longitudinal direction, and the biasing film applies a magnetic field in the direction of the initial state to the free layer, so that when the external magnetic field is eliminated, the free layers The magnetization direction of each magnetic region can be stably restored to the direction of the initial state for a long period of time (for example, refer to Patent Document 1). (Patent Document 1) Japanese Patent Laid-Open No. 2002-299728 (FIG. 42 to FIG. 44) refers to the plan view 17 of the free layer and the biasing film to explain the magnetization state of the free layer and the biasing film. In FIG. 17, the free layer 100 is formed to have a longitudinal direction in the X-axis direction, and a pair of bias films 101 and 102 are provided at both ends of the longitudinal direction.

At the stage when these films are formed, as shown by the arrows in FIG. 17(A), the magnetization directions of the magnetic regions of the free layer 100 and the bias films 101 and 102 do not coincide with the longitudinal direction of the free layer, that is, the direction of the initial state. For the magnetic sensor with the free layer 100 and the biasing films 101 and 102 in this state, if an external magnetic field of varying magnitude is applied in the direction perpendicular to the longitudinal direction of the free layer (the Y-axis direction), the resistance value of the magnetic sensor is checked, As shown in Figure 18(A), hysteresis occurs. It can be seen that in a magnetic sensor in which the magnetization directions of the free layer 100 and the biasing films 101 and 102 do not coincide with the longitudinal direction of the free layer, the resistance value when the external magnetic field is near "0" is as shown in Figure 18(A) It fluctuates within the range indicated by the arrow, and as a result, this magnetic sensor cannot detect a small magnetic field with high accuracy.

Next, for the magnetic sensor with the free layer 100 and the biasing films 101, 102 in the state shown in FIG. 17(A), if the free layer 100 is applied in the longitudinal direction (the positive X-axis direction) of the magnetic sensor larger than the biasing films 101, 102 The magnetic field of the coercivity Hc of the free layer 100 initializes the free layer 100 and magnetizes the biasing films 101 and 102. As shown in FIG. 17(B), the free layer 100 and the magnetic regions of the biasing films 101 and 102 The direction of magnetization is consistent with the direction of the initial state.

If an external magnetic field that changes within a range smaller than the coercivity of the biasing films 101 and 102 is applied to the magnetic sensor in this state in the Y-axis direction, the magnetization direction of each magnetic region of the free layer 100 is as shown in Fig. 17 ( C) changes as shown in C), and then, if the external magnetic field is eliminated, the magnetization direction of each magnetic region of the free layer 100 returns to the direction of the initial state shown in FIG. 17(D), which is the same as that of FIG. 17(B). In this case, when the resistance value of the magnetic sensor is checked, as shown in FIG. 18(B), the hysteresis decreases, and the resistance value when the external magnetic field is near "0" becomes substantially constant. Therefore, the magnetic sensor that has performed the initialization of the free layer 100 and the magnetization of the bias films 101 and 102 can detect the minute magnetic field with high accuracy.

However, if a magnetic sensor (a magnetic sensor that has undergone initialization of the free layer 100 and magnetization of the biasing films 101 and 102) is applied to a magnetic sensor that is smaller but larger than the biasing films 101 and 102, and is in contact with When there is a main component of the external magnetic field in the direction opposite to the initial state (the negative direction of the X-axis), the magnetization direction of each magnetic region of the free layer changes from the state shown in Fig. 19(A) to Fig. 19(B) After the state changes, even if the external magnetic field is eliminated, as shown in FIG. 19(C), the magnetization direction of each magnetic region of the free layer 100 does not coincide with the direction of the initial state (recovery). As a result, there is a problem that the magnetic sensor has hysteresis against the change of the external magnetic field again, and the detection accuracy of the magnetic field deteriorates.

Summary of the invention

Therefore, an object of the present invention is to provide a magnetic sensor that can maintain a good detection accuracy even after a large external magnetic field is applied. In addition, another object of the present invention is to provide a magnetic sensor capable of efficiently magnetizing the biasing film, a manufacturing method of the magnetic sensor, and a magnet array suitable for the manufacturing method.

The present invention is characterized in that it is composed of a giant magnetoresistance effect element having a spin-switch film, the spin-switch film has a pinned layer, a conductive liner layer, and a free layer, and includes: a biasing film, which is composed of By generating a bias magnetic field in a predetermined direction on the free layer, the magnetization direction of the magnetic region of the free layer is maintained in the direction in the predetermined initial state by a permanent magnet; The magnetic field for initialization is applied to the free layer in the same direction as the bias magnetic field. Therefore, by applying a strong magnetic field to the free layer, even in the magnetization direction of each magnetic region of the free layer In the case of confusion, the direction of the magnetization can be reliably returned to the initial state.

In this way, since the initialization coil is energized under predetermined conditions, it generates the initialization magnetic field for returning the magnetization direction of each magnetic region of the free layer to the same direction as the bias magnetic field generated by the biasing film. When a strong magnetic field is applied to the magnetic sensor and the magnetization direction of each magnetic region of the free layer is disturbed for some reason, it can be corrected. As a result, it is possible to provide a magnetic field resistance without hysteresis. A magnetic sensor that can detect small magnetic fields with high accuracy over a long period of time.

Another feature of the present invention is to provide a method for manufacturing a magnetic sensor having a magnetoresistance effect element, the magnetoresistance effect element having a pinned layer on a substrate, a free layer, and applying a bias magnetic field to the free layer The magnetic bias film is composed of a permanent magnet, and the resistance value of the magnetoresistance effect element changes according to the angle formed by the magnetization direction of the pinned layer and the magnetization direction of the free layer. The method includes the following steps: a step of preparing a magnet array, which arranges a plurality of permanent magnets on grid points of a square grid, and at the same time, the polarity of the magnetic pole of each permanent magnet is the same as that of other magnetic poles adjacent to each other with the shortest distance. Different; the process of manufacturing a single wafer, which spreads a plurality of island-shaped unit films on the substrate, the unit film including a film that becomes the pinning layer, a film that becomes the free layer, and a film that becomes the biasing filmMembrane; Perform a magnetizing step, which arranges the single chip in a position adjacent to the magnet array, so that the single chip and the magnet array have a predetermined relative positional relationship, and use a magnetic field to become the multiple The magnetic field is formed between one magnetic pole of the magnetic poles of the magnet array and the other magnetic poles of the magnetic poles of the magnet array adjacent to the magnetic pole at the shortest distance.

The structure of the magnet array is that a plurality of permanent magnets are arranged on the grid points of a square grid, so that the polarities of the magnetic poles of each permanent magnet are the same as those of other magnetic poles adjacent to each other with the shortest distance in the horizontal view (in the same plane). Sex is different. Therefore, above the magnet array, in a horizontal view of the magnet array, a magnetic field in the right direction is formed from one N pole to the S pole existing on the right side of the N pole, and from the N pole to the N pole. The S pole on the side forms an upward magnetic field, from the N pole to the S pole on the left of the N pole, a left direction magnetic field, and from the N pole to the S pole on the lower side of the N pole. Direction of the magnetic field (see Figure 13). Similarly, for a certain S pole, a magnetic field in the left direction is formed from the N pole existing on the right side of the S pole, and a magnetic field in the downward direction is formed from the N pole existing on the upper side of the S pole. The N pole on the left side of the pole forms a rightward magnetic field, and the N pole existing on the lower side of the S pole forms an upward magnetic field.

In the method described above, for the magnet array forming such a magnetic field, single chips are arranged adjacent to each other with a predetermined relative positional relationship, and the single chips are spread on the substrate with a plurality of films including the pinned layer, and The free layer film, the island-shaped unit film that becomes the film of the biasing film, and the magnetic field formed by the magnet array are used to make the plurality of unit films become the film of the biasing film. magnetic. Therefore, it is possible to efficiently manufacture a magnetic sensor in which the magnetizing directions of the biasing films on a single substrate cross each other (vertical in this case).

More specifically, the step of manufacturing the single wafer includes forming a film of each component layer of a plurality of unit films, so that the film of each component layer of the plurality of unit films is formed to have a long axis and a short axis. At the same time as the shape of the axis, at least one long axis of the film that becomes the free layer of the plurality of unit films is perpendicular to the long axis of the film that becomes the other free layer, and the film that becomes the biasing film is formed so that each Both ends of the film of the free layer in the long axis direction. The predetermined relative positional relationship in the step of magnetizing the film that becomes the biasing film is the relative positional relationship between the single wafer and the magnet array, that is, the magnetic field formed by the magnet array makes The magnetization direction of the film forming this biasing film coincides with the long axis direction of the film forming the free layer on both ends of the biasing film.

In addition, at this time, it is preferable to include the following process of arranging the single wafer adjacent to the magnet array so that the single wafer and the magnet array have a relative positional relationship different from the predetermined relative positional relationship, and The magnetic field formed by the magnet array pinning becomes the magnetization direction of the film of the pinned layer of the plurality of unit films.

In this way, since the magnetization magnet array for the film that becomes the biasing film is also used when fixing the magnetization direction of the pinned layer, it is possible to efficiently and inexpensively manufacture the magnetization directions of the pinned layer on a single substrate to cross each other (the In the case of vertical) magnetic sensor (two-axis magnetic sensor that can respectively detect the magnetic field in the vertical direction).

In addition, according to the present invention, there is provided a magnet array, which is configured to provide a plurality of permanent magnets having a substantially rectangular parallelepiped shape and a substantially square cross-sectional shape perpendicular to a certain central axis of the rectangular parallelepiped so as to have substantially square end faces The center of gravity of is consistent with the grid points of the square grid. At the same time, the polarities of the magnetic poles of the installed permanent magnets (the polarities of the magnetic poles appearing on the end surface) and the polarities of the other permanent magnets adjacent to each other with the shortest distance (The polarity of the magnetic pole appearing on the end face) is different.

That is, the arrangement of the plurality of permanent magnets in the magnet array is such that the center of gravity of each of the substantially square end faces coincides with the grid points of the square grid, and the sides of each of the substantially square end faces correspond to the other on the same row. The sides of the end face exist on substantially the same straight line, the end face exists on the substantially same plane, and the polarity of the magnetic pole of the end face is different from the polarity of the magnetic pole of the end face of the other permanent magnet adjacent to the shortest distance.

As described above, due to the use of the related magnet array, the magnetization of the film that becomes the biasing film of the biaxial magnetic sensor and/or the magnetization direction of the layer that becomes the pinning layer can be efficiently fixed, so it can be inexpensive To manufacture the two-axis magnetic sensor.

In addition, the magnet array is also "a kind of magnet array, which has a substantially rectangular parallelepiped shape, the shape of a cross section perpendicular to a certain central axis of the rectangular parallelepiped is substantially square, and is on the substantially square end surface perpendicular to the central axis A plurality of permanent magnets having magnetic poles are formed, and the center of gravity of each of the plurality of permanent magnets having the substantially square end faces coincides with the grid points of the square grid, and at the same time, the One side of the end face of one permanent magnet of the plurality of permanent magnets and one side of the end face of the other permanent magnets arranged in the same row are substantially on the same straight line, and the existence of the end faces of the plurality of permanent magnets The magnetic poles formed on the end faces of the two permanent magnets adjacent to each other at the shortest distance among the plurality of permanent magnets are on substantially the same plane. The polarities of the magnetic poles formed on the end faces of the two permanent magnets are different." The magnetization of the same is ideal.

In addition, the "a magnet array has a substantially rectangular parallelepiped shape, the shape of a cross section perpendicular to a certain central axis of the rectangular parallelepiped is substantially square, and the substantially square end surface perpendicular to the central axis is formed The plurality of permanent magnets of the magnetic poles also have a thin-plate-shaped yoke made of magnetic material; each of the plurality of permanent magnets has the substantially square end surface and the center of gravity is consistent with the grid points of the square grid, and is arranged One side of the end surface of one permanent magnet of the plurality of permanent magnets in any one row of the square grid and one side of the end surface of the other permanent magnets arranged in the same row are on substantially the same straight line , The end faces of all the plurality of permanent magnets exist on substantially the same plane, and the polarities formed on the end faces of the two permanent magnets adjacent to each other at the shortest distance among the plurality of permanent magnets are different; The yoke has a plurality of through holes having substantially the same shape as the substantially square cross-section of the permanent magnets at substantially the same positions as the plurality of permanent magnets arranged, and the permanent magnets are inserted into the through holes. For the magnet, the plane on which the end face of the permanent magnet is present exists between the upper surface and the lower surface of the yoke. "It is ideal for magnetizing the biasing film of the magnetic sensor or the like.

Since the magnet array has a yoke made of a magnetic material, the lines of magnetic force from the permanent magnet can be guided to the desired place. Therefore, the magnetization of the biasing film of the magnetic sensor and the like can be efficiently performed by the magnet array.

In this case, it is preferable that the yoke forms a through hole that becomes an air gap between through holes adjacent to each other at the shortest distance among the through holes.

In this magnet array, the through holes forming an air gap are formed between the through holes adjacent to each other at the shortest distance (the end faces of the permanent magnets whose magnetic poles are inserted into the two through holes), so that the magnetic flux is concentrated in the through holes. The space in the hole and the vicinity of the through hole. In other words, the magnet array can generate a strong magnetic field with a certain direction in a local narrow space area. Therefore, the magnetization of the bias film of the magnetic sensor and the like can be efficiently performed by the magnet array.

Preferably, the yoke has an opening at a position surrounding the center of gravity of a square formed by connecting each grid point of the square grid in a horizontal view.

The magnet array not only has the aforementioned through holes, but also has openings. The position where the opening is formed is a position surrounding the center of gravity of the square formed by connecting the grid points of the square grid. This position is the part where the lines of magnetic force from each magnetic pole cross and the magnetic field becomes unstable. Thus, the instability of the magnetic field is eliminated by the opening. As a result, the magnetic field generated between the magnetic poles of the opposite poles adjacent to each other at the shortest distance becomes a straight line, and a more stable and uniform magnetic field can be locally generated in the vicinity of the through hole. Therefore, according to the related magnet array, it is possible to effectively perform magnetization of the bias film of the magnetic sensor and the like.

In addition, each through hole of the yoke preferably has a square portion and an edge portion, the square portion being the same square as the permanent magnet having a substantially square cross-section in plan view, and the edge portion is separated from the square portion. The corners protrude to the outside of the square.

In the case of forming a square through hole on the yoke by etching, if the etching is not sufficient, the corners of the square will be arc-shaped, and the permanent magnet may not be inserted. In this regard, in the yoke, since the edge portion is also etched, the permanent magnet can be accurately inserted into the through hole.

Description of the drawings

Fig. 1 is a plan view of an embodiment of the magnetic sensor of the present invention; Fig. 2 is a schematic enlarged plan view of the first X-axis GMR element shown in Fig. 1; Fig. 3 is cut by a plane along line 1-1 of Fig. 2 A schematic plan view of the first X-axis GMR element shown in FIG. 2; FIG. 4 is a diagram showing the spin switch film (spin valve film) structure of the first X-axis GMR element shown in FIG. 2; The solid line shows the change in the resistance value of the magnetic field that changes in the X-axis direction of the first X-axis GMR element shown in FIG. 1, and the broken line shows the change in the resistance value of the magnetic field that changes in the Y-axis direction. ;

Fig. 6(A) is an equivalent circuit of the X-axis magnetic sensor of the magnetic sensor shown in Fig. 1, and Fig. 6(B) shows the output change of the X-axis magnetic sensor in the X-axis direction. Fig. 7(A) is the equivalent circuit of the Y-axis magnetic sensor of the magnetic sensor shown in Fig. 1, and Fig. 7(B) shows the change in the Y-axis direction of the Y-axis magnetic sensor The graph of the output change of the magnetic field; Fig. 8(A) is the equivalent circuit of another X-axis magnetic sensor that the magnetic sensor shown in Fig. 1 has, and Fig. 8(B) is a graph showing the X-axis magnetic sensor The graph of the output change of the magnetic field changing in the X-axis direction; Fig. 9(A) is the equivalent circuit of another Y-axis magnetic sensor of the magnetic sensor shown in Fig. 1, and Fig. 9(B) shows the A graph of the output change of the magnetic field changing in the Y-axis direction of the Y-axis magnetic sensor; FIG. 10 is a plan view of the quartz glass on which the spin switch film is formed in the process of manufacturing the magnetic sensor shown in FIG. 1; 11 is a plan view showing a metal plate and a permanent bar magnet inserted into the metal plate, the metal plate is used to prepare the magnet array used in manufacturing the magnetic sensor shown in FIG. 1; FIG. 12 is a manufacturing view 1 is a cross-sectional view of the magnet array used in the magnetic sensor; FIG. 13 is a perspective view of a part of the magnet of the magnet array shown in FIG. 12; FIG. 14 is a diagram showing the manufacture of the magnet shown in FIG. Fig. 15 is a conceptual diagram showing a method of magnetizing the biasing film of each GMR element of the magnetic sensor shown in Fig. 1; Fig. 16 is a diagram showing the pinning shown in Fig. 1 A conceptual diagram of the method of magnetization direction of the pinned layer of each GMR element of the magnetic sensor; FIG. 17 is a plan view showing the form of magnetization of the free layer and the biasing film of the GMR element, and FIG. 17(A) is a diagram showing Fig. 17(B) is a view showing the state of the biasing film before magnetization, and Fig. 17(C) is a view showing the state after applying an external magnetic field Fig. 17(D) is a diagram showing the state after the external magnetic field is eliminated; Fig. 18(A) is a diagram showing the resistance of the external magnetic field of the GMR element in the state before magnetization of the biasing film Fig. 18(B) is a graph showing the change in the resistance value of the external magnetic field of the GMR element in the state after the magnetization of the biasing film; Fig. 19 is a graph showing the freedom of the GMR element A plan view of the form of magnetization of the layer and the biasing film. FIG. 19(A) shows a state in which no external magnetic field is applied after the magnetization of the biasing film. FIG. 19(B) shows that a strong external Fig. 19(C) is a diagram showing the state of the magnetic fieldFig. 20 is a schematic enlarged plan view of the first X-axis GMR element in another embodiment of the magnetic sensor related to the present invention; Fig. 21 is an implementation of another magnetic sensor (N type) of the present invention Fig. 22 is a plan view of another embodiment of the magnetic sensor (S type) of the present invention; Fig. 23 is a partial plan view of the yoke of the magnet array MB related to the present invention; Fig. 24 is shown in Fig. 23 A partial enlarged view of the yoke; Figure 25 is a cross-sectional view of the yoke cut by a plane along line 2-2 of Figure 24; Figure 26 is a plan view of a through hole of the yoke shown in Figure 23; Figure 27 is the present Fig. 28 is a partial plan view of the array substrate of the magnet array MB according to the invention; Fig. 29 is a thin plate body that becomes the material of the array substrate shown in Fig. 27; 30 is a diagram showing a process of manufacturing the magnet array MB; FIG. 31 is a diagram showing a process of manufacturing the magnet array MB; FIG. 32 is a diagram showing a process of manufacturing the magnet array MB; FIG. 33 is A diagram showing a process of manufacturing the magnet array MB; FIG. 34 is a perspective view of a part of the magnet and the yoke from which the magnet array MB is taken out; FIG. 35 is a partial cross-sectional view of the magnet array MB; FIG. 36 is for explaining the magnet array A plan view of the magnet array MB of the magnetic field involved in MB; FIG. 37 is a plan view of the magnet array MA for explaining the magnetic field involved in the magnet array MA; A conceptual diagram of the method of the magnetization direction of the pinned layer of each GMR element of the sensor; FIG. 39 shows the magnet array MB when magnetizing the biasing film of each GMR element of the magnetic sensor shown in FIG. 21 and FIG. 22 A cross-sectional view of the positional relationship with the substrate; FIG. 40 is a conceptual diagram showing a method of magnetizing the biasing film of each GMR element of the magnetic sensor shown in FIGS. 21 and 22.A partial plan view of the array substrate shown in FIG. 29; FIG. 29 is a thin plate body that becomes the material of the array substrate shown in FIG. 27; FIG. 30 is a diagram showing a process of manufacturing the magnet array MB; FIG. 31 is a diagram showing Fig. 32 is a diagram showing a process of manufacturing the magnet array MB; Fig. 33 is a diagram showing a process of manufacturing the magnet array MB; Fig. 34 is a diagram showing a process of manufacturing the magnet array MB; A perspective view of a part of the magnet of the array MB and the yoke; FIG. 35 is a partial cross-sectional view of the magnet array MB; FIG. 36 is a plan view of the magnet array MB for explaining the magnetic field involved in the magnet array MB; FIG. 37 is for explaining the magnet A plan view of the magnet array MA of the magnetic field involved in the array MA; FIG. 38 is a conceptual diagram showing a method of pinning the magnetization direction of the pinned layer of each GMR element of the magnetic sensor shown in FIGS. 21 and 22; 39 is a cross-sectional view showing the positional relationship between the magnet array MB and the substrate when the bias film of each GMR element of the magnetic sensor shown in FIG. 21 and FIG. 22 is magnetized; FIG. 40 is a cross-sectional view showing the magnetization diagram 21 And a conceptual diagram of the method of the biasing film of each GMR element of the magnetic sensor shown in FIG. 22.A partial plan view of the array substrate shown in FIG. 29; FIG. 29 is a thin plate body that becomes the material of the array substrate shown in FIG. 27; FIG. 30 is a diagram showing a process of manufacturing the magnet array MB; FIG. 31 is a diagram showing Fig. 32 is a diagram showing a process of manufacturing the magnet array MB; Fig. 33 is a diagram showing a process of manufacturing the magnet array MB; Fig. 34 is a diagram showing a process of manufacturing the magnet array MB; A perspective view of a part of the magnet of the array MB and the yoke; FIG. 35 is a partial cross-sectional view of the magnet array MB; FIG. 36 is a plan view of the magnet array MB for explaining the magnetic field involved in the magnet array MB; FIG. 37 is for explaining the magnet A plan view of the magnet array MA of the magnetic field involved in the array MA; FIG. 38 is a conceptual diagram showing a method of pinning the magnetization direction of the pinned layer of each GMR element of the magnetic sensor shown in FIGS. 21 and 22; 39 is a cross-sectional view showing the positional relationship between the magnet array MB and the substrate when the bias film of each GMR element of the magnetic sensor shown in FIG. 21 and FIG. 22 is magnetized; FIG. 40 is a view showing the magnetization diagram 21 And a conceptual diagram of the method of the biasing film of each GMR element of the magnetic sensor shown in FIG. 22.

Explanation of Reference Signs 10, 50... Magnetic sensor

11-14, 21-24, 51-54, 61-64...GMR elements 11a-14a, 21a-24a, 51a-54a, 61a-64a...Narrow band-shaped parts 11b-14b, 21b-24b, 51b-54b, 61b ~64b...Biasing films 31-34, 41-44, 71-74, 81-84...initializing coil MA...Magnet array specific embodiments Hereinafter, embodiments of the magnetic sensor according to the present invention will be described with reference to the drawings. This magnetic sensor is classified into N type and S type according to the manufacturing method described later. FIG. 1 is a plan view enumerating an N-type magnetic sensor 10 and an S-type magnetic sensor 50. The N-type magnetic sensor 10 and the S-type magnetic sensor 50, except for the fixed magnetization direction of the pinned layer as shown by the black arrow in FIG. 1, and the initial free layer as shown by the hollow arrow in FIG. Except for the fact that the magnetization directions of the states are different from each other, they have substantially the same shape and structure. Therefore, the following description focuses on the N-type magnetic sensor 10.

As shown in FIG. 1, the magnetic sensor 10 has a rectangular (substantially square) shape with sides along the X axis and the Y axis perpendicular to each other in a plan view, and its structure includes: A single substrate (single substrate) 10a with a very small thickness in the Z-axis direction; a plurality of insulating layers 10b (including wiring layers in the insulating layer) laminated on the substrate 10a shown in FIG. 3; A total of eight GMR elements 11-14, 21-24, and eight initialization coils 31-34, 41-44 are on the uppermost layer 10b1 of the insulating layer 10b.

The first X-axis GMR element 11 is formed below approximately the center of the substrate 10a in the Y-axis direction and near the end in the negative X-axis direction, as shown by the black arrow in FIG. 1, and the pinning magnetization direction of the pinning layer is the X-axis Negative direction. The second X-axis GMR element 12 is formed above the substantially center of the substrate 10a in the Y-axis direction and near the end in the negative X-axis direction, as shown by the black arrow in FIG. 1, and the pinning magnetization direction of the pinning layer is the X-axis Negative direction. The third X-axis GMR element 13 is formed above the substantially center of the substrate 10a in the Y-axis direction and near the end in the positive X-axis direction, as shown by the black arrow in FIG. 1, and the pinning magnetization direction of the pinning layer is the X-axis Positive direction. The fourth X-axis GMR element 14 is formed below substantially the center of the substrate 10a in the Y-axis direction and near the end in the positive X-axis direction, as shown by the black arrow in FIG. 1, and the pinning magnetization direction of the pinning layer is the X-axis Positive direction.

The first Y-axis GMR element 21 is formed on the left of approximately the center of the substrate 10a in the X-axis direction and near the end in the positive direction of the Y-axis, as shown by the black arrow in FIG. 1, and the pinning magnetization direction of the pinning layer is Y Positive axis direction. The second Y-axis GMR element 22 is formed on the right of approximately the center of the substrate 10a in the X-axis direction and near the end in the positive direction of the Y-axis, as shown by the black arrow in FIG. 1, and the pinning magnetization direction of the pinning layer is Y Positive axis direction. The third Y-axis GMR element 23 is formed on the right of approximately the center of the substrate 10a in the X-axis direction and near the end in the negative direction of the Y-axis, as shown by the black arrow in FIG. 1, and the pinning magnetization direction of the pinning layer is Y Axis negative direction. The fourth Y-axis GMR element 24 is formed on the left of approximately the center of the substrate 10a in the X-axis direction and near the end in the negative direction of the Y-axis, as shown by the black arrow in FIG. 1, and the pinning magnetization direction of the pinning layer is Y Axis negative direction.

The respective GMR elements 11 to 14 and 21 to 24 have substantially the same structure except for their arrangement in the substrate 10a. Therefore, the structure of the first X-axis GMR element 11 will be described below as a representative example.

As shown in plan view 2 and FIG. 3 in which a schematic cross-sectional view of the first X-axis GMR element 11 is cut along a plane along line 1-1 of FIG. 2, the first X-axis GMR element 11 includes a spin switch film SV and Y A plurality of narrow band-shaped parts 11a...11a whose axial direction is the longitudinal direction and the hard ferromagnetic material such as CoCrPt formed under the two ends of each narrow band-shaped part 11a in the longitudinal direction (Y-axis direction) have high coercivity. Biasing films (a hard ferromagnetic thin film layer, a film that becomes a permanent magnetic film by magnetization) 11b...11b, and biasing films 11b...11b composed of materials that are comparable to the high-angle type. Each narrow band-shaped portion 11a...11a extends in the X-axis direction on the upper surface of each biasing film 11b...11b, and is joined to the adjacent narrow band-shaped portion 11a to form a so-called "zigzag shape", and at the same time, each biasing film 11b The upper surface of ...11b is magnetically coupled with each of the biasing films 11b...11b.

As shown in the film structure in FIG. 4, the spin switch film SV of the first X-axis GMR element 11 is composed of a free layer (free layer) F layered on a substrate, namely, a substrate 10a, and a film thickness of 2.4 composed of Cu. The conductive liner layer S of nm (24 Ȧ), the pinned layer (pinning layer) P, and the top layer C of 2.5 nm (25 Ȧ) film thickness made of titanium (Ti) or tantalum (Ta) are formed.

The free layer F is a layer whose magnetization direction changes with the direction of an external magnetic field. It consists of a CoZrNb amorphous magnetic layer 11-1 with a thickness of 8 nm (80 Ȧ) formed directly above the substrate 10a and a CoZrNb amorphous magnetic layer. The NiFe magnetic layer 11-2 with a thickness of 3.3 nm (33 ) on 11-1, and the CoFe layer 11- with a thickness of about 1 to 3 nm (10 to 30 ) formed on the NiFe magnetic layer 11-2 3 constitute. The CoZrNb amorphous magnetic layer 11-1 and the NiFe magnetic layer 11-2 constitute a soft magnetic thin film layer. The CoFe layer 11-3 is used to prevent the diffusion of Ni of the NiFe magnetic layer 11-2 and Cu11-4 of the pad layer S.

The pinned layer (pinning layer) P is a layer formed by superimposing a CoFe magnetic layer 11-5 with a thickness of 2.2 nm (22 ) and an antiferromagnetic film 11-6 with a thickness of 24 nm (240 ). The antiferromagnetic film 11-6 is formed of a PtMn alloy containing 45 to 55% by mole of Pt. The CoFe magnetic layer 11-5 is affixed to the magnetized (magnetized) antiferromagnetic film 11-6 in a manner of exchange coupling, so as to form the direction of magnetization (magnetization vector) pinning (fixing) the pin in the negative X-axis direction Tie layer.

The biasing films 11b...11b are used to maintain the coaxial anisotropy of the free layer F, and provide the free layer in the longitudinal direction of the free layer F, that is, the negative direction of the Y axis (the direction shown by the hollow arrows in FIGS. 1 and 2). F applies a bias magnetic field.

The first X-axis GMR element 11 constructed in this way, as shown by the solid line in FIG. 5, the resistance value of the external magnetic field that changes along the X-axis varies in proportion to the external magnetic field in the range of -Hc to +Hc, and the external magnetic field is as As shown by the dashed line in FIG. 5, the resistance value is substantially constant relative to the external magnetic field that changes along the Y axis.

Next, the initialization coils 31-34, 41-44 are demonstrated. As shown in Figs. 1 and 3, the initialization coils 31 to 34, 41 to 44 are located approximately directly below the GMR elements 11 to 14, 21 to 24, respectively, and are buried in the lower insulating layer 10b2 through the uppermost layer 10b1 of the insulating layer . The initialization coils 31 to 34 and 41 to 44 have the same shape as each other, and the relative positional relationship with the GMR element directly above each corresponding is also the same as each other. For each corresponding GMR element, the direction indicated by the hollow arrow in FIG. 1 is applied to each corresponding GMR element. Magnetic field for initialization.

Hereinafter, the initialization coil 31 is taken as a representative example for description. The initialization coil 31 is wound into a substantially rectangular shape in a horizontal view, and has a plurality of initialization magnetic field generating parts 31a...31a, and the plurality of initialization magnetic field generating parts 31a...31a is directly below the first X-axis GMR element 11 in a horizontal view, and extends linearly in a direction (X-axis direction) perpendicular to the longitudinal direction of the narrow band portion 11a of the first X-axis GMR element 11. In addition, one end portion 31b and the other end portion 31c of the initialization coil are respectively connected to the positive and negative poles of the stabilized power supply, and when the predetermined conditions are satisfied, a predetermined current is applied to the initialization coil 31, as shown in the hollow in Figure 1. As shown by the arrow, the initializing magnetic field in the negative direction of the Y-axis is applied to the narrow band portion 11 a of the first X-axis GMR element 11.

Next, regarding the X-axis magnetic sensor (magnetic sensor with the X-axis direction as the magnetic field detection direction) and the Y-axis magnetic sensor (the Y-axis direction as the magnetic field detection) composed of the GMR elements 11-14 and GMR elements 21-24, respectively Direction magnetic sensor). The X-axis magnetic sensor is shown in the equivalent circuit in Fig. 6(A). The first to fourth X-axis GMR elements 11 are connected in a full bridge through wires not shown in Fig. 1 ~14 and constitute. In addition, in FIG. 6(A), the graphs shown at positions adjacent to each of the first to fourth X-axis GMR elements 11 to 14 show the characteristics of the GMR elements adjacent to each graph (to the external The change of the resistance value R of the magnetic field). This point is the same for FIGS. 7 and 9. Hx and Hy in these graphs respectively show the external magnetic field whose magnitude changes along the X axis and the Y axis.

In such a structure, the connection point of the first X-axis GMR element 11 and the fourth X-axis GMR element 14 and the connection point of the second X-axis GMR element 12 and the third X-axis GMR element 13 are respectively stable with those not shown. The positive pole and negative pole (ground) of the piezoelectric power supply are connected to the potential +V (5 (V) in this example) and -V (0 (V) in this example) respectively. Then, the potential difference Vox between the connection point of the first X-axis GMR element 11 and the third X-axis GMR element 13 and the connection point of the fourth X-axis GMR element 14 and the second X-axis GMR element 12 is taken out as a sensor output. As a result, as shown in FIG. 6(B), the X-axis magnetic sensor displays an output voltage Vox that changes substantially in proportion to the external magnetic field Hx that changes along the X-axis.

As shown in the equivalent circuit of FIG. 7(A), the Y-axis magnetic sensor is constructed by connecting the first to fourth Y-axis GMR elements 21 to 24 in a full bridge type through wires not shown in FIG. 1. Then, the connection point of the first Y-axis GMR element 21 and the fourth Y-axis GMR element 24, and the connection point of the second Y-axis GMR element 22 and the third Y-axis GMR element 23 are respectively connected to the positive electrode of the stabilized power supply not shown. , The negative (ground) connection, respectively give potential +V (in this example, 5 (V)) and potential -V (in this example, 0 (V)). In addition, the potential difference Voy between the connection point of the first Y-axis GMR element 21 and the third Y-axis GMR element 23 and the connection point of the fourth Y-axis GMR element 24 and the second Y-axis GMR element 22 is taken out as a sensor output. As a result, as shown in FIG. 7(B), the Y-axis magnetic sensor displays an output voltage Voy that changes substantially in proportion to the external magnetic field Hy that changes along the Y-axis. The above is the structure of the N-type magnetic sensor 10.

On the other hand, the S-type magnetic sensor 50, as shown in FIG. 1, includes GMR elements 51-54, 61-64 and initialization coils 71-74, 81-84, and has the same structure as the magnetic sensor 10, including the X axis Magnetic sensor and Y-axis magnetic sensor.

That is, the X-axis magnetic sensor of the magnetic sensor 50 is shown in the equivalent circuit of FIG. 8(A), and the first to fourth X-axis GMR elements 51 to 54 are connected in a full bridge type through wires not shown in FIG. constitute. In such a structure, the connection point of the first X-axis GMR element 51 and the fourth X-axis GMR element 54 and the connection point of the second X-axis GMR element 52 and the third X-axis GMR element 53 are respectively stable with those not shown. The positive pole and negative pole (ground) of the piezoelectric power supply are connected to the potential +V (5 (V) in this example) and -V (0 (V) in this example) respectively. Then, the potential difference Vox between the connection point of the first X-axis GMR element 51 and the third X-axis GMR element 53 and the connection point of the fourth X-axis GMR element 54 and the second X-axis GMR element 52 is taken out as a sensor output . As a result, as shown in FIG. 8(B), the X-axis magnetic sensor displays an output voltage Vox that changes substantially in proportion to the external magnetic field Hx that changes along the X-axis.

In addition, the Y-axis magnetic sensor of the magnetic sensor 50 is shown in the equivalent circuit of FIG. 9(A), and the first to fourth Y-axis GMR elements 61 to 64 are connected in a full bridge type through wires not shown in FIG. constitute. Then, the connection point of the first Y-axis GMR element 61 and the fourth Y-axis GMR element 64, and the connection point of the second Y-axis GMR element 62 and the third Y-axis GMR element 63 are respectively connected to the positive electrode of a stabilized power supply not shown. , The negative (ground) connection, respectively give potential +V (in this example, 5 (V)) and potential -V (in this example, 0 (V)). In addition, the potential difference Voy between the connection point of the fourth Y-axis GMR element 64 and the second Y-axis GMR element 62 and the connection point of the first Y-axis GMR element 61 and the third Y-axis GMR element 63 is taken out as a sensor output . As a result, as shown in FIG. 9(B), the Y-axis magnetic sensor displays an output voltage Voy that changes substantially in proportion to the external magnetic field Hy that changes along the Y-axis.

Next, a method of manufacturing the magnetic sensors 10 and 50 configured as described above will be described. First, as shown in the plan view 10, on the rectangular quartz glass 10a1 that will become the substrates 10a and 50a thereafter, each insulating layer 10b is laminated simultaneously with the formation of predetermined wiring or LSI, and the initialization coil 31 is formed in the insulating layer 10b2. After -34, 41-44, 71-74, 81-84, the uppermost insulating layer 10b1 is formed thereafter (refer to FIGS. 1 to 3).

Next, a plurality of films M constituting the GMR elements 11 to 14, 21 to 24, 51 to 54, 61 to 64 are formed in an island shape. Specifically, the bias film 11b is formed, and the films M constituting the GMB elements 11-1421-24, 51-54, 61-64 are formed thereon. The film uses an ultra-high vacuum device to form a film to a precise thickness through continuous stacking. The film M is formed into a wiring pattern, and a plurality of parts that become island-shaped GMR elements are formed. These films M are formed so that when the quartz glass 10a1 is cut along the dashed line in FIG. 10 through the subsequent cutting process and divided into the respective magnetic sensors 10 and 50 shown in FIG. GMR elements 11-14, 21-24, 51-54, 61-64 are shown.

Next, as shown in the plan view 11, a rectangular metal plate 91 is prepared, which has a plurality of square through holes formed in a square lattice structure (that is, arranged along the X axis and the Y axis at equal intervals with respect to the X axis and the Y axis. A square through hole on the side of the shaft), a permanent bar magnet 92...92 with a rectangular parallelepiped shape approximately the same as the through hole is inserted into each through hole of the metal plate 91, so that the permanent bar magnet 92... The end surface of the magnetic pole of 92 is parallel to the metal plate 91. At this time, the permanent bar magnets 92...92 are arranged so that the polarities of the magnetic poles adjacent to each other at the shortest distance in the plane including the end faces of the permanent bar magnets 92...92 are different. In addition, the magnitudes of the magnetic charges of the permanent bar magnets 92...92 used are all approximately the same.

Next, as shown in FIG. 12 showing a cross-section along the XZ plane, a plate 93 made of transparent quartz glass with a thickness of about 0.5 mm is prepared. The plate 93 has a rectangular shape approximately the same as that of the metal plate 91 and is made of glue. The mixture adheres the upper surface of the permanent bar magnets 92...92 (the surface opposite to the end surface where the magnetic poles are formed) and the lower surface of the plate 93, and the metal plate 91 is removed from below. At this stage, the permanent bar magnets 92...92 and the plate 93 form a magnet array MA constructed in the following manner, that is, a substantially rectangular parallelepiped shape and a cross-sectional shape perpendicular to a certain central axis of the rectangular parallelepiped are often substantially square. A permanent magnet, so that the center of gravity with square end faces is consistent with the grid point of the square grid, and at the same time, the polarity of the permanent magnet's magnetic pole is different from the polarity of other permanent magnets adjacent to it and separated by the shortest distance .

Fig. 13 is a perspective view showing a state where the four permanent bar magnets 92...92 are taken out. It can be seen from this figure that a magnetic field is formed in the end faces of the permanent bar magnets 92...92 (the end faces where the magnetic poles are formed), and the magnetic field is from an N pole. The S poles adjacent to the N pole with the shortest distance are different in the direction of 90°. In this embodiment, the magnetic field is used as the biasing films 11b-14b, 21b-24b, 51b-54b, 61b-64b for the GMR elements 11-14, 21-24, 51-54, 61-64 The magnetizing magnetic field and the magnetic field when the magnetization direction of each pinned layer P (pinned layer of the pinned layer P) is fixed.

That is, first, as shown in FIG. 14, the quartz glass 10a1 on which the film M used as the GMR element is formed is arranged so that the surface where the film M used as the GMR element is formed is connected to the upper surface of the plate 93, and the plate 93 is clamped by the jig C. And the quartz glass 10a1 are fixed to each other. At this time, as shown in the plan view 15, the figure focuses on the parts that will become the magnetic sensors 10 and 50 later, and enlarges the parts of the two magnetic sensors 10 and 50 respectively, and the quartz glass 10a1 and the magnet array MA are arranged oppositely , The intersections CP of the cutting lines CL of the quartz glass 10a1 that are the sides of the magnetic sensors 10 and 50 are made to coincide with the respective centers of gravity of the permanent bar magnets 92...92. Therefore, as shown by the arrow in FIG. 15, in the state where the quartz glass 10a1 is placed on the upper surface of the plate 93, the longitudinal magnetic field of the narrow band portion of the film M is applied to each film M that becomes the GMR element.

In this embodiment, while magnetizing the bias films 11b-14b, 21b-24b, 51b-54b, 61b-64b using the relevant magnetic field, the magnetization direction of each magnetic region of the free layer F is made to be the same as that in the initial state. The direction is the same. That is, the magnetization of each magnetic region of the free layer F is initialized.

Next, as shown in the plan view of FIG. 16, the relative positional relationship between the quartz glass 10a1 forming the film M of the GMR element and the magnet array MA (plate 93) is changed, and the configuration is formed so that the surface of the film M of the GMR element and The upper surface of the plate 93 is connected. At this time, the quartz glass 10a1 and the magnet array MA are arranged opposite to each other so that each intersection CP of the cut line CL of the quartz glass 10a1 on each side of the magnetic sensors 10, 50 and the four permanent bar magnets 92 adjacent to each other. 92 has the same center of gravity. Therefore, as shown by the arrow in FIG. 16, in a state where the quartz glass 10a1 is placed on the upper surface of the plate 93, a magnetic field in a direction perpendicular to the longitudinal direction of the narrow band portion of the film M is applied to each film M serving as a GMR element.

In this embodiment, a heat treatment (regularization heat treatment) for fixing the magnetization direction of the pinned layer P (pinned layer of the pinned layer P) is performed using a related magnetic field. That is, in the state shown in FIG. 16, the plate 93 and the quartz glass 10a1 are fixed to each other by the jig C, heated to 250°C to 280°C in a vacuum, and left in this state for about 4 hours.

After that, the quartz glass 10a1 is taken out, wiring and the like connecting the respective films M are formed, and finally, the quartz glass 10a1 is cut along the broken line (cutting line CL) shown in FIG. 10 and the like. In this way, many magnetic sensors 10 and 50 shown in FIG. 1 are manufactured at the same time.

As described above, since the embodiment has the biasing films 11b-11b, which are composed of permanent magnets, they are provided at both ends of the free layer F in the longitudinal direction and at the same time make it generate a predetermined direction on the free layer (the free layer Therefore, the magnetization direction of each magnetic region of the free layer in a state where there is no external magnetic field can be stabilized and maintained in a prescribed direction.

In addition, the initialization coils 31 to 34, 41 to 44 are energized under predetermined conditions, and are generated to return the magnetization direction of each magnetic region of the free layer to the same direction as the direction of the biasing magnetic field generated by the biasing film (that is, The longitudinal direction of the free layer) is used for initializing the magnetic field. Therefore, even when a strong magnetic field is applied to the free layer and the magnetization direction of each magnetic region of the free layer is disturbed, the magnetization direction can be reliably returned to the original state. As a result, since the magnetic sensors 10 and 50 generate small hysteresis when the external magnetic field is maintained near "0" in response to changes in the external magnetic field, it is possible to detect minute magnetic fields with high accuracy over a long period of time.

In addition, according to the embodiment of the manufacturing method described above, a magnet array MA is prepared, which is constructed in such a way that a plurality of permanent magnets are arranged on the grid points of a square grid so that the polarity of the magnetic pole of each permanent magnet is adjacent to the shortest distance between them. The polarity of the other magnetic poles is different; the magnetic field formed by the magnet array MA performs the initialization of the magnetization direction of the magnetic regions of the free layer and the magnetization of the bias film, and the magnetization direction of the magnetic layer that becomes the pinned layer is pinned The pinning process. Therefore, it is possible to efficiently and easily form a plurality of GMR elements with different magnetic field detection directions (perpendicular to each other) on a single substrate, and it is possible to inexpensively manufacture a single substrate composed of a single substrate that can detect at least various magnetic fields that vary in magnitude in mutually perpendicular directions. Magnetic sensor.

In addition, in the aforementioned embodiment, the GMR film (the film of the GMR element) is formed after the patterned bias film (magnet) is formed, and the regularization process is performed after the patterned GMR film M is formed. However, this regularization process may be performed before the GMR film M is formed, and the biasing film may be formed after the GMR film.

Next, another embodiment (second embodiment) of the magnetic sensor according to the present invention will be described. Like the magnetic sensor, the magnetic sensor includes the N type shown in the plan view in FIG. 21 and the S type shown in the plan view in FIG. 22. The N-type magnetic sensor 110 and the S-type magnetic sensor 150, except for the fixed magnetization direction of the pinned layer shown by the black arrows in FIGS. 21 and 22, and the magnetization direction of the initial state of the free layer shown by the open arrows Except for the fact that they are different from each other, they have substantially the same shape and structure. In addition, in FIG. 21 and FIG. 22, the illustration of the initialization coil is abbreviate|omitted.

The N-type magnetic sensor 110 has the same structure as the magnetic sensor 10 except for the difference in the configuration of the GMR element and the initialization coil of the N-type magnetic sensor 10. That is, the structure of the magnetic sensor 110 includes: a single substrate 110a that is the same as the single substrate 10a; an insulating layer that is the same as the insulating layer 10b; a total of 8 GMR elements 111 to 114, which are formed on the uppermost layer of the insulating layer, 121~124; A total of 8 coils for initialization. The relative positional relationship of the GMR elements 111 to 114, 121 to 124 and the eight initialization coils is the same as the relative positional relationship of the GMR elements 11 to 14, 21 to 24 and the initialization coils 31 to 34, 41 to 44. In addition, similar to the GMR elements 11 to 14, the GMR elements 111 to 114 are connected to the full bridge to form an X-axis magnetic sensor. Like the GMR elements 21 to 24, the GMR elements 121 to 124 are connected to the full bridge to form a Y-axis magnetic sensor.

The first X-axis GMR element 111 is formed near the center of the substrate 110a in the Y-axis direction and near the end in the negative X-axis direction. The second X-axis GMR element 112 is formed at a substantially central portion of the substrate 110 a in the Y-axis direction, at a position slightly separated from the first X-axis GMR element 111 in the positive X-axis direction. The third X-axis GMR element 113 is formed at approximately the center of the substrate 110a in the Y-axis direction and near the end in the positive X-axis direction. The fourth X-axis GMR element 114 is formed at a substantially central portion in the Y-axis direction of the substrate 110a, at a position slightly separated from the third X-axis GMR element 113 in the negative direction of the X-axis. The longitudinal directions of the first to fourth X-axis GMR elements 111 to 114 are the Y-axis direction.

The first Y-axis GMR element 121 is formed near the center portion of the substrate 110a in the X-axis direction and near the end portion in the positive direction of the Y-axis. The second Y-axis GMR element 122 is formed at a substantially center portion of the substrate 110 a in the X-axis direction, at a position slightly separated from the first Y-axis GMR element 121 in the negative direction of the Y-axis. The third Y-axis GMR element 123 is formed near the center of the substrate 110a in the X-axis direction and near the end in the negative Y-axis direction. The fourth Y-axis GMR element 124 is formed at a substantially center portion of the substrate 110 a in the X-axis direction, at a position slightly separated from the third Y-axis GMR element 123 in the positive direction of the Y-axis. Each longitudinal direction of the first to fourth Y-axis GMR elements 121 to 124 is the X-axis direction.

The S-type magnetic sensor 150 has the same structure as the magnetic sensor 50 except for the difference in the arrangement of the GMR element and the initialization coil of the S-type magnetic sensor 50. That is, the structure of the magnetic sensor 150 includes: a single substrate 150a that is the same as the single substrate 50a; an insulating layer that is the same as the insulating layer 10b; a total of 8 GMR elements 151 to 154, which are formed on the uppermost layer of the insulating layer, 161~164; A total of 8 coils for initialization. The relative positional relationship of the GMR elements 151 to 154, 161 to 164 and the eight initialization coils is the same as the relative positional relationship of the GMR elements 51 to 54, 61 to 64 and the initialization coils 71 to 74, 81 to 84. In addition, similar to the GMR elements 51 to 54, the GMR elements 151 to 154 are connected to the full bridge to form an X-axis magnetic sensor. As with the GMR elements 61 to 64, the GMR elements 161 to 164 are connected to the full bridge to form a Y-axis magnetic sensor.

The positional relationship of the opposed substrate 150a of the first to fourth X-axis GMR elements 151 to 154 is the same as the positional relationship of the opposed substrate 110a of the first to fourth X-axis GMR elements 111 to 114. The longitudinal directions of the first to fourth X-axis GMR elements 151 to 154 are the Y-axis direction. In addition, the positional relationship of the opposed substrate 150a of the first to fourth X-axis GMR elements 161 to 164 is the same as the positional relationship of the opposed substrate 110a of the first to fourth Y-axis GMR elements 121 to 124. The longitudinal directions of the first to fourth Y-axis GMR elements 161 to 164 are the X-axis direction.

Next, a method of manufacturing the magnetic sensors 110 and 150 configured as described above will be described. In this manufacturing method, the magnet array MA described above and the magnet array MB different from the magnet array MA are used.

First, while the magnet array MA is prepared by the method described above, the magnet array MB is prepared by the method described below. Before the description of the manufacturing method of the magnet array MB, each part constituting the magnet array MB will be described. The magnet array MB is composed of a yoke (yoke plate) 200, an array substrate 210, and a plurality of permanent magnets (permanent bar magnets) 230.

The yoke 200 is shown in FIGS. 23-25. FIG. 23 is a partial plan view of the yoke 200, FIG. 24 is a partial enlarged view of FIG. 23, and FIG. 25 is a cross-sectional view of the yoke 200 taken along the line 2-2 of FIG. 24. The yoke 200 is a thin plate body made of a magnetic material (for example, 42 alloy (Fe-42Ni alloy), etc.) having a higher permeability than air. Preferably, the yoke 200 is made of a material with high saturation and high permeability (for example, a permalloy or silicon steel plate). The planar shape of the yoke 200 is rectangular. The plate thickness of the yoke 200 is 0.15 mm in this example. The yoke 200 has a plurality of through holes 201. The through hole 201 is viewed as a substantially square shape. The plurality of through holes 201 are arranged in a square grid. That is, the center of gravity of each through hole 201 coincides with the square grid point SP shown in FIG. 24. In a horizontal view, any side of the through hole 201 is parallel to one side of the adjacent through hole 201. In other words, any one side of the through hole 201 and the side of the other through hole 201 formed in the same row as the through hole 201 exist on the same straight line.

As shown in FIG. 26 showing the planar shape of one through hole 201, in a plan view, each through hole 201 has a shape including a square portion 201a and an edge portion (arc-shaped portion, R portion) 201b. The shape of the square portion 201b is a square. The edge portion 201b protrudes from each corner of the square portion 201b to the outside of the square. More specifically, the outer shape of the edge portion 201b is a circular arc shape having a center RP on the diagonal CR of the square portion 201a.

Between the through-holes 201 adjacent to each other with the shortest distance apart, through-holes 202 that become air gaps are formed. The shape of the through hole 202 is substantially rectangular in plan view. The long side of the through hole 202 is parallel to one side of the square portion 201 b of the through hole 201 adjacent to the through hole 202. The length of the long side of the through hole 202 is approximately the same as the length of one side of the square portion 201a, or only slightly shorter than the length of one side of the square portion 201a. The length of the short side of the through hole 202 is larger than the longitudinal length of the film M forming the GMR elements 111 to 114, 121 to 124, 151 to 154, and 161 to 164.

The yoke 200 also has an opening (magnetic flux control hole) 203. The opening 203 is formed at a position surrounding the center of gravity SQ of a square formed by connecting the grid points SP of the square grid to each other in a plan view. The opening 203 has a circular shape centered on the center of gravity SQ in a plan view.

The array substrate 210 shown in FIGS. 27 and 28 is a substrate on which a thin plate body 210a made of the magnetic material (for example, a high-permeability alloy) shown in FIG. 29 is processed. The array substrate 210 has substantially the same shape as the yoke 200 in a plan view. The array substrate 210 has a plurality of grooves 210b. The plurality of grooves 210b are provided at the same place (same position) as the through hole 201 of the yoke 200 in a plan view. The shape of the groove 210b is substantially the same as the square portion 201a of the through hole 201.

The permanent bar magnet 230 (refer to FIG. 31) has a rectangular parallelepiped shape. The permanent bar magnet 230 cuts the permanent bar magnet 230 with a plane perpendicular to the long central axis opposite to the rectangular parallelepiped. The shape of the cross section of the permanent bar magnet 230 is formed into a square substantially the same as the through hole 201 (and the groove 210b). The magnetic poles of the permanent bar magnet 230 are formed in the vicinity of the two end faces having the square shape. The magnetic charges of the plurality of permanent bar magnets 230 are all substantially equal in size.

Next, the manufacturing method of the magnet array MB will be described. First, a plate body to be the yoke 200 is prepared, and the plate body is etched to form through holes 201, through holes 202, and openings 203. Next, a thin plate body 210a to be the substrate 210 for an array is prepared, and the thin plate body 210a is etched (half-etched) to form a groove 210b.

Next, as shown in the perspective view 30 and the cross-sectional view 31, a prismatic horizontal column 220 is arranged on the array substrate 210. The horizontal column 220 is arranged between an arbitrary row formed by the plurality of grooves 210b of the array substrate 210 and the plurality of grooves 210b that are parallel to the row and constitute adjacent rows. When the horizontal column 220 is arranged in this way, the length of the horizontal column 220 in the Z-axis direction is shorter than the length between the two end surfaces of the magnetic poles forming the permanent bar magnet 230. In addition, in FIG. 30, the edge portion 201b is omitted.

Next, the yoke 200 is placed on the horizontal column 220. At this time, the yoke 200 is arranged so that the through hole 201 (the square portion 201a) of the yoke 200 coincides with the groove 210b of the array substrate 210 in plan view. In other words, in the state where the yoke 200 is arranged on the horizontal post 220, both the groove 210b and the through hole 201 are in the Z-axis direction. In addition, in order to facilitate such an arrangement, a mark (positioning mark) for positioning may be provided on the yoke 200 and the array substrate 210.

Next, a plurality of permanent bar magnets 230 are inserted into the plurality of through holes 201 of the yoke 200, respectively. When the permanent bar magnet 230 is inserted, one end surface of one magnetic pole forming the permanent bar magnet 230 is abutted with the upper surface of the groove 210b of the array substrate 210. As a result, the other end surfaces (hereinafter referred to as "upper surface") of other magnetic poles arranged to form the plurality of permanent bar magnets 230 exist in substantially the same plane (on the same plane). In addition, at this time, in the plane including the upper surface of the permanent bar magnet 230, the permanent bar magnet 230 is arranged so that the polarities of the magnetic poles adjacent to the shortest distance are different. As a result, the permanent bar magnet 230 is arranged as shown in FIG. 32. In this state, by inserting the permanent bar magnet 230 into the groove 210b and the through hole 201 of the yoke 200, the permanent bar magnet 230 can be prevented from moving in the X-axis direction and the Y-axis direction.

Next, while using the opening 203 of the yoke 200, the yoke 200 is lifted upward (in the positive direction of the Z-axis). More specifically, the yoke 200 is lifted while pinching the two openings 203 using pin mounting. The other opening 203 is used repeatedly to perform such an operation, and the entire yoke 200 is slowly lifted. At this time, as shown in FIG. 33, adjust the height (distance from the array substrate 210) of the yoke 200 so that the upper surface of the permanent bar magnet 230 (the other end surface of the magnetic poles of the permanent bar magnet 230 is formed) The plane formed by the sum) is located between the upper surface 200up and the lower surface 200dn of the yoke 200. In other words, the yoke 200 is lifted so that the upper surface of the permanent bar magnet 230 is located within the thickness of the yoke 200. Furthermore, the plane formed by the upper surface 200up of the yoke 200 and the upper surface of the permanent bar magnet 230 may be aligned. After that, while the horizontal post 220 is pulled out, the yoke 200 is fixed to the array substrate 210. From the above, the magnet array MB is completed.

FIG. 34 is a perspective view showing a state in which the permanent bar magnets 230...230 of the four magnet arrays MB are taken out. It can be seen from this figure that a magnetic field is formed on the upper surface of the permanent bar magnets 230...230 (the end surface where the magnetic poles are formed), and the magnetic field is located at 90° from one N pole to the S pole adjacent to the N pole with the shortest distance. The direction of ° is different. In this embodiment, the magnetic field generated by the magnet array MB is used as a magnetic field for magnetizing the biasing films of the GMR elements 111 to 114, 121 to 124, 151 to 154, and 161 to 164.

In this magnet array MB, through holes 202 that become an air gap are formed between (upper surfaces) of permanent bar magnets 230 having different polarities of magnetic poles adjacent to each other at the shortest distance. In this way, as shown in FIG. 35, the magnetic flux is concentrated in the space in the through hole 202 and in the vicinity of the through hole 202. In other words, the magnet array MB can generate a strong magnetic field with a constant direction in a local narrow space area (the area near the through hole 202).

36 and 37 are plan views respectively showing the magnetic flux patterns of the magnet array MB and the magnet array MA with arrows. By comparing the two figures, it can be seen that since the magnet array MB not only has the aforementioned through hole 202 but also has an opening 203, the magnetic field generated between the permanent bar magnets 230 of different poles adjacent to each other with the shortest distance is linear. It is possible to locally generate a magnetic field that is more stable and the same strength than the magnet array MA.

Since the magnet arrays MA and MB can be prepared through the above, the specific manufacturing method of the magnetic sensors 110 and 150 will be described below.

First, a substrate (quartz glass, a single wafer as the substrate 110a1 shown in FIG. 39 described later) is prepared, and the substrate is formed as GMR elements 111 to 114, 121 to 124, 151 to 154, and 161 to 164.MembraneM. The film M. This substrate is formed in the same manner as the substrate 10a1 shown in FIG. 10. In addition, the film M formed on the substrate is arranged so that when the substrate is cut by the subsequent cutting process, the individual magnetic sensors 110 and 150 shown in FIGS. 21 and 22 are formed.

Next, as shown in the plan view of FIG. 38, the substrate and the magnet array MA (plate 93) on which the film M serving as the GMR element is formed are arranged, and their relative positional relationship is fixed. At this time, the surface of the substrate on which the film M serving as the GMR element is formed is connected to the upper surface of the board 93 (see FIG. 14). In addition, the substrate and the magnet array MA are arranged opposite to each other so that each intersection CP of the cutting line CL of the substrate on each side of the magnetic sensors 110 and 150 coincides with the center of gravity of the four adjacent permanent bar magnets 92...92. Therefore, as shown by the arrow in FIG. 38, in a state where the substrate is placed on the magnet array MA, a magnetic field in a direction perpendicular to the longitudinal direction of the narrow band portion of the film M is applied to each film M serving as a GMR element.

In this second embodiment, a heat treatment for fixing the magnetization direction of the pinned layer P (pinned layer of the pinned layer P) is performed using a related magnetic field. That is, in the state shown in FIG. 38, the plate 93 and the substrate are fixed to each other by the clamp C (see FIG. 14), they are heated to 250°C to 28°C in a vacuum, and the state is maintained for about 4 hours.

Next, as shown in FIG. 39, the substrate 110a1 on which the film M serving as the GMR element is formed is arranged so that the surface on which the film M serving as the GMR element is formed is connected to the upper surface 200up of the yoke 200 of the magnet array MB. At this time, as shown in a partially enlarged plan view 40, the substrate 110a1 and the magnet array MB are arranged opposite to each other so that the intersections CP of the cutting line CL of the substrate 110a1 on each side of the magnetic sensors 110 and 150 and the water bar magnet 230...230 has the same center of gravity. At this time, each film M serving as a GMR element is arranged inside the opening 202 of the yoke 200 in a plan view. As a result, in the state where the substrate 110a1 is placed on the upper surface 200up of the yoke 200, as shown by the arrow in FIG. 40, the longitudinal magnetic field of the narrow band portion of the film M is applied to each film M that becomes the GMR element.

In this second embodiment, while magnetizing the bias film using the relevant magnetic field, the magnetization direction of each magnetic region of the free layer is aligned with the direction in the initial state. That is, the magnetization of each magnetic region of the free layer is initialized.

Then, the substrate 110a1 is taken out, and wiring and the like connecting the respective films M are formed. Finally, the substrate 110a1 is cut along the cutting line CL shown in FIGS. 38 and 40. In this way, many single-chip (single substrate) magnetic sensors 110 shown in FIG. 21 and a single-chip (single substrate) magnetic sensor 150 shown in FIG. 22 can be manufactured at the same time.

In this way, in the second embodiment, the magnet array MB is used to locally generate a strong magnetic field, and this magnetic field performs magnetization of the biasing film of the GMR element. The magnet array MB has a yoke 200 that forms a through hole 202 that functions as an air gap. Therefore, by using the magnet array MB, a magnetic field with the same strength can be generated in the space near the through hole 202. Therefore, even when a magnetic material with a large coercive force is used in the biasing film, the biasing film can be reliably made Magnetized. As a result, even after a disturbance (for example, a strong external magnetic field) is applied, it is possible to provide a highly reliable magnetic sensor 110, 150 in which the magnetization of the free layer can be stably restored to the original direction.

In addition, in the yoke 200 of the magnet array MB, an opening 203 is formed in a portion where the lines of magnetic force from each magnetic pole cross and the magnetic field becomes unstable. As a result, since the directivity of the magnetic lines of force is stable, the magnetic field near the through hole 202 can be further stabilized. In addition, the opening 203 is used when adjusting the distance between the array substrate 210 of the magnet array MB and the yoke 200 (the height of the yoke 200). As a result, since the position of the yoke 200 can be easily and ideally adjusted in the height direction, it is possible to generate an optimal magnetic field at the portion where the biasing film of the GMR element to be magnetized is located.

In addition, the through hole 201 of the yoke 200 of the magnet array MB is not a square, but has a shape of an edge portion 201b that protrudes from each corner of the square to the outside of the square. Therefore, when the through hole 201 is formed by etching, even if the corner portion is not sufficiently etched, the permanent bar magnet 230 can be reliably inserted into the through hole 201. In addition, such an edge part may be provided in the corner part of the groove 210b.

The present invention is not limited to the above-mentioned embodiments, and various modifications can be adopted within the scope of the present invention. For example, as shown in FIG. 20 taking the first X-axis GMR element 301 as a representative example, the narrow band-shaped portion 301a may also be separated by the upper part of the biasing films 301b...301b provided below both ends thereof. In addition, the initialization coil 302 may be a double-row spiral coil connected to spiral coils 302-1 and 302-2 having a center point P1 and a center point P2, respectively. In this case, the first XGMR element 301 is arranged between the center points P1 and P2. As a result, the wires passing through the initialization coil 302 below the first XGMR element 301 are parallel to each other and in the same direction (perpendicular to Electric current flows in the longitudinal direction of each of the narrow band-shaped portions 301a to generate the above-mentioned initializing magnetic field. In addition, the initialization coil may be a multilayer coil or a loop coil. In addition, an inspection coil may be provided in the insulating layer above or below the initialization coil (in the Z-axis direction) at the same time, and the inspection coil may generate a magnetic field perpendicular to the initialization magnetic field generated by the initialization coil. Magnetic field for inspection to inspect the function of each GMR element in the direction.