JP4953569B2 - Thin film magnetoresistive element and magnetic sensor using thin film magnetoresistive element - Google Patents

Description

  The present invention relates to a thin film magnetoresistive element including a giant magnetoresistive thin film in a gap portion of a soft magnetic film, a manufacturing method thereof, and a magnetic sensor using the thin film magnetoresistive element.

  Conventionally, as a thin film magnetoresistive element having a remarkably large magnetoresistive effect and high magnetic field sensitivity than those using a permalloy alloy or the like, as shown in FIG. 18, the first and second soft resistors are within the same plane. The magnetic films 101 and 102 are arranged to face each other through a required gap 103, and a giant magnetoresistive thin film 104 such as a nano granular alloy thin film is formed in the gap 103 and a part of the upper surface of the soft magnetic films 101 and 102 following the gap 103. What was formed is proposed (for example, refer patent document 1).

  In this thin film magnetoresistive element, the gap length Lg is set to 20 times or less the film thickness of the soft magnetic films 101 and 102, whereby the giant magnetoresistive element disposed in the gap 103 when the soft magnetic films 101 and 102 are magnetized. Since a magnetic field corresponding to the magnetization of the soft magnetic films 101 and 102 can be applied to the thin film 104, the magnetoresistive effect (MR ratio) of the giant magnetoresistive thin film 104 can be saturated with a small external magnetic field, and the magnetic field sensitivity can be increased. Can be significantly increased.

Thus, since this thin film magnetoresistive element can greatly increase not only the MR ratio but also the magnetic field sensitivity, a magnetic head (MR head) that enables high-speed and high-density magnetic recording, and high resolution The present invention can be applied to a magnetic sensor (MR sensor) in a servo motor or a rotary encoder that enables the detection of the above signal.
Japanese Patent No. 3466470

By the way, in order to obtain the effects as described above, it is necessary to effectively cause the magnetic field flowing from the soft magnetic films 101 and 102 to act on the giant magnetoresistive thin film 104. That is, the electric resistance of the giant magnetoresistive thin film 104 is sufficiently large (1 × 10 ⁴ μΩ · cm to 1 × 10 ⁹ μΩ · cm) as compared with the electric resistance of the soft magnetic films 101 and 102. Current flows through the giant magnetoresistive thin film 104 between the gaps 103. Therefore, it is necessary to effectively apply a magnetic field to the giant magnetoresistive thin film 104 between the gaps 103.

However, since the giant magnetoresistive thin film 104 is formed not only in the gap 103 but also on a part of the upper surface of the soft magnetic films 101 and 102 in the thin film magnetoresistive element having the above configuration, As shown in FIG. 18 , the electric and magnetic paths from the soft magnetic film 101 to the soft magnetic film 102 pass through the giant magnetoresistive thin film 104 formed in the gap 103 from the end face of the soft magnetic film 101. Dispersed into a path to the end face of the film 102 and a path from the upper surface of the soft magnetic film 101 to the upper surface of the soft magnetic film 102 through the giant magnetoresistive thin film 104 formed outside the gap 103.

  For this reason, the thin film magnetoresistive element having the above-described configuration has a reduced magnetic flux density of the magnetic flux passing through the giant magnetoresistive thin film 104 and has a non-uniform path length, compared to a thin film magnetoresistive element having a single magnetic flux path. Magnetic field sensitivity decreases. Further, since the magnetic field sensitivity of the thin film magnetoresistive element is a composite value of local magnetic field sensitivities in each path, the linearity of the magnetic field sensitivity is deteriorated as compared with the thin film magnetoresistive element having a single magnetic flux path. Therefore, since the magnetic field is not effectively applied to the gap 103 through which most of the current flows, the degree of the MR effect is reduced particularly when the magnetic field is weak.

  The present invention has been made to solve such problems of the prior art, and an object thereof is to provide a thin film magnetoresistive element having high magnetic field sensitivity and good linearity, and An object of the present invention is to provide a method for manufacturing such a thin film magnetoresistive element inexpensively and easily, and to provide a practical magnetic sensor using the thin film magnetoresistive element.

In order to solve the above problems, the present invention provides a giant magnetoresistive thin film, first and second soft magnetic films having one end electrically and magnetically connected via the giant magnetoresistive thin film, A nonmagnetic insulating film interposed between at least one of the first soft magnetic film and the second soft magnetic film and the giant magnetoresistive thin film, and the first and second soft magnetic films detect signals. In the thin film magnetoresistive element provided with a terminal portion for the above, the nonmagnetic insulating film is formed on the upper surface of the first soft magnetic film formed on the insulating substrate, the upper surface and the end surface of the nonmagnetic insulating film, and the The giant magnetoresistive thin film is formed on an end face of the first soft magnetic film, and the nonmagnetic insulating film is formed on the insulating substrate so that one end is in contact with the giant magnetoresistive thin film, and an upper surface of the nonmagnetic insulating film is formed. end surface and the first soft magnetic end on said nonmagnetic insulating layer The second soft magnetic film is formed so as to be in contact with the giant magnetoresistive thin film formed on the end face of the film, and the second soft magnetic film is formed from the first soft magnetic film via the giant magnetoresistive thin film by the nonmagnetic insulating film. The electric path and magnetic path leading to the soft magnetic film are restricted only in the arrangement direction of the first soft magnetic film and the second soft magnetic film.

According to such a configuration, the non-magnetic insulating film is formed on the upper surface of the first soft magnetic film, and the second soft magnetic film is formed on the end surface side of the first soft magnetic film via the giant magnetoresistive thin film. Since the electric and magnetic paths from the upper surface of the first soft magnetic film to the second soft magnetic film through the giant magnetoresistive thin film can be blocked, the second soft magnetism from the first soft magnetic film through the giant magnetoresistive thin film can be blocked. The electric path and magnetic path leading to the film can be restricted only in the arrangement direction of the first soft magnetic film and the second soft magnetic film. Therefore, it is possible to improve the magnetic field sensitivity and the linearity thereof. In addition, since the magnetic flux path and the current path coincide with each other, the MR effect can be effectively exhibited even in a weak magnetic field.

  According to the present invention, in the thin film magnetoresistive element having the above structure, the second soft magnetic film is laminated on the nonmagnetic insulating film formed so that one end is in contact with the giant magnetoresistive thin film. Made the configuration.

  According to such a configuration, the end face of the first soft magnetic film and the end face of the second soft magnetic film are arranged to face each other through the giant magnetoresistive thin film by laminating the second soft magnetic film on the nonmagnetic insulating film. Therefore, the electric path and magnetic path from the first soft magnetic film through the giant magnetoresistive thin film to the second soft magnetic film can be restricted only in the thickness direction of the giant magnetoresistive thin film.

  According to the present invention, in the thin film magnetoresistive element having the above structure, the giant magnetoresistive thin film is formed with a granular magnetic film in which ferromagnetic fine particles are dispersed in an insulator matrix.

  Since the granular magnetic film has a remarkably large MR ratio compared to a giant magnetoresistive thin film of an alloy system such as a permalloy alloy, the output signal strength of the magnetic head and the magnetic sensor can be obtained by using the granular magnetic film as the giant magnetoresistive thin film. Can be increased. In addition, since the granular magnetic film can obtain a large MR ratio in one layer, the manufacturing of the thin film magnetoresistive element can be facilitated as compared with the case where a giant magnetoresistive thin film having a multilayer structure is used.

  According to the present invention, in the thin film magnetoresistive element having the above structure, the giant magnetoresistive thin film formed between the first soft magnetic film and the second soft magnetic film has a thickness of 0.05 μm or more. It was set as the structure which is less than 0 micrometer.

  According to the study by the inventors of the present application, when a gap is formed in a soft magnetic film formed on a substrate by ion beam etching or the like, and then a giant magnetoresistive thin film is sputtered in the formed gap, the gap length is When the thickness is 1 μm or less, the giant magnetoresistive thin film does not sufficiently enter the gap, and it becomes difficult to form a uniform giant magnetoresistive thin film. On the other hand, in the case where the thin film magnetoresistive element is composed of a laminate of the first and second soft magnetic films, the giant magnetoresistive thin film, and the nonmagnetic insulating film, there is no manufacturing limitation on the gap length. The thickness of the giant magnetoresistive thin film formed between the first soft magnetic film and the second soft magnetic film can be 0.05 μm or more and less than 1.0 μm. Therefore, the gap length of the thin film magnetoresistive element can be substantially reduced, and the magnetic field sensitivity of the thin film magnetoresistive element can be increased.

Further, the present invention is to solve the above problems, the method of manufacturing a thin film magnetoresistive element, and the following configuration.

Forming a first soft magnetic film insulation substrate, wherein the steps of forming a non-magnetic insulating layer on the upper surface of the first soft magnetic film, the first soft magnetic film end surface and the subsequent the non of Forming a giant magnetoresistive thin film on the insulating substrate following the one end surface and top surface of the magnetic insulating film and one end surface of the first soft magnetic film; and one end of the non-magnetic insulating film on the insulating substrate and Forming a second soft magnetic film in contact with the end face of the first soft magnetic film and the giant magnetoresistive thin film formed on the insulating substrate. Thereby, the thin film magnetoresistive element according to claim 1 is obtained.

In order to solve the above-described problems, the present invention provides a magnetic sensor having a giant magnetoresistive thin film and first and second ones that are electrically and magnetically connected at one end via the giant magnetoresistive thin film. A soft magnetic film; a nonmagnetic insulating film interposed between at least one of the first soft magnetic film and the second soft magnetic film and the giant magnetoresistive thin film; A thin film magnetoresistive element in which a signal detecting terminal portion is provided on the soft magnetic film, wherein the nonmagnetic insulating film is formed on an upper surface of the first soft magnetic film formed on the insulating substrate, The giant magnetoresistive thin film is formed on the top and end faces of the magnetic insulating film and the end face of the first soft magnetic film, and the nonmagnetic insulating film is formed on the insulating substrate so that one end is in contact with the giant magnetoresistive thin film. and, the non-magnetic insulating end the non-magnetic on the upper surface of the film The second soft magnetic film is formed in contact with the giant magnetoresistive thin film formed on the end face of the edge film and the end face of the first soft magnetic film, and the nonmagnetic insulating film passes through the giant magnetoresistive thin film. Two thin-film magnetoresistive elements in which an electric path and a magnetic path from the first soft magnetic film to the second soft magnetic film are restricted only in an arrangement direction of the first soft magnetic film and the second soft magnetic film, The bridge circuit is provided with two opposite sides and a fixed resistance element on the other two opposite sides.

  As described above, when the thin film magnetoresistive element in which the electric path and the magnetic path from the first soft magnetic film to the second soft magnetic film are regulated in one direction via the giant magnetoresistive thin film by the nonmagnetic insulating film, Since dispersion and magnetic flux path length non-uniformity can be suppressed, a magnetic sensor with high magnetic field sensitivity and excellent linearity can be obtained. Further, when a magnetic sensor is configured with a bridge circuit having two thin film magnetoresistive elements on two opposite sides and a fixed resistance element on the other two opposite sides, it acts on the thin film magnetoresistive element by the null method. Magnetic field fluctuations can be detected, and influences such as fluctuations in the power supply voltage and the input impedance and nonlinearity of the detector can be eliminated, so that highly accurate magnetic field detection can be performed.

  In the thin film magnetoresistive element of the present invention, a nonmagnetic insulating film is interposed in a required portion between the first and second soft magnetic films and the giant magnetoresistive thin film, and the first soft magnetism is interposed via the giant magnetoresistive thin film. Since the electric path and the magnetic path from the film to the second soft magnetic film are regulated in one direction, the dispersion of the magnetic flux and the nonuniformity of the magnetic flux path length can be suppressed, and the magnetic field sensitivity and its linearity can be improved. In addition, since the magnetic flux path and the current path coincide with each other, the MR effect can be effectively exhibited even in a weak magnetic field.

  The method of manufacturing a thin film magnetoresistive element of the present invention includes a first soft magnetic film and a giant magnetoresistive thin film, a second soft magnetic film and a giant magnetoresistive thin film, and a first soft magnetic film and a second soft magnetic film. Since it includes a step of forming a nonmagnetic insulating film at a required portion between the magnetic film and the magnetic and magnetic paths from the first soft magnetic film to the second soft magnetic film through the giant magnetoresistive thin film in one direction A regulated thin film magnetoresistive element can be manufactured.

  The magnetic sensor according to the present invention includes a thin film magnetoresistive element in which an electric path and a magnetic path from the first soft magnetic film to the second soft magnetic film are regulated in one direction through a giant magnetoresistive thin film by a nonmagnetic insulating film. In addition, it is possible to suppress magnetic flux dispersion and magnetic flux path length non-uniformity, and to obtain a magnetic sensor with high magnetic field sensitivity and excellent linearity. Further, when a magnetic sensor is configured with a bridge circuit having two thin film magnetoresistive elements on two opposite sides and a fixed resistance element on the other two opposite sides, it acts on the thin film magnetoresistive element by the null method. Magnetic field fluctuations can be detected, and influences such as fluctuations in the power supply voltage and the input impedance and nonlinearity of the detector can be eliminated, so that highly accurate magnetic field detection can be performed.

  A first embodiment of a thin film magnetoresistive element according to the present invention will be described with reference to FIGS. FIG. 1 is a plan view of a thin film magnetoresistive element according to the first embodiment, and FIG. 2 is a cross-sectional view taken along line AA of FIG.

  As shown in FIGS. 1 and 2 (a), the thin film magnetoresistive element 1A of this example is formed on the insulating substrate 2 and the insulating substrate 2, and one end thereof is arranged to face the gap through a required gap g. The band-shaped first soft magnetic film 3 and second soft magnetic film 4 are formed on the upper surface of the first soft magnetic film 3 near the gap g and on the upper surface of the second soft magnetic film 4 near the gap g. The nonmagnetic insulating film 5, the end surfaces of the first and second soft magnetic films 3 and 4 facing the gap g on the insulating substrate 2 in the gap g, and the end surface and the upper surface of the nonmagnetic insulating film 5 that follows the nonmagnetic insulating film 5 It consists of a giant magnetoresistive thin film 6 formed in part.

  The insulating substrate 2 is formed into a required shape and size with a high-rigidity nonmagnetic insulator such as an inorganic dielectric, plastics, or nonmagnetic ceramic.

As shown in FIG. 1, the first soft magnetic film 3 connects a narrow width portion 3a having a required gap width Wg, a wide width portion 3b wider than the gap width Wg, and both the portions 3a and 3b. It consists of the taper part 3c. Further, as shown in FIG. 1, the second soft magnetic film 4 includes a narrow width portion 4a having a required gap width Wg, a wide width portion 4b wider than the gap width Wg, and both the portions 4a and 4b. And a taper portion 4c connecting the two. The first and second soft magnetic films 3 and 4 are formed by sputtering a soft magnetic material having a high saturation magnetic flux density such as a Co ₇₇ Fe ₅ Si ₉ B ₈ alloy or a permalloy alloy (Fe ₆₅ Ni ₃₅ ) on the insulating substrate 2. A gap g having a gap length of Lg is provided between the first and second soft magnetic films 3 and 4. Although the end faces of the narrow width portions 3a and 4a can be formed perpendicular to the insulating substrate 2, it is easy to form the giant magnetoresistive thin film 6 having a uniform thickness with respect to the end faces and is formed on the end faces. In order to suppress the change in the characteristics of the giant magnetoresistive thin film 6, it is desirable to incline at an inclination angle θt of 20 to 45 degrees with respect to the perpendicular M standing on the insulating substrate 2.

The nonmagnetic insulating film 5 electrically insulates between the upper surface of the first soft magnetic film 3 and the giant magnetoresistive thin film 6 and between the second soft magnetic film 4 and the giant magnetoresistive thin film 6. It is formed by sputtering an inorganic dielectric such as SiO ₂ or Al ₂ O ₃ on the first soft magnetic film 3.

The giant magnetoresistive thin film 6 has a remarkably large MR ratio compared to an alloy-type giant magnetoresistive thin film such as a permalloy alloy, and a large MR ratio can be obtained in one layer. A granular magnetic film in which magnetic fine particles are dispersed is formed. Examples of the granular magnetic film include 32 vol% CoFe—MgF ₂ and Co _38.6 Y _14.0 O _47.4 . In the example of FIG. 2A, the giant magnetoresistive thin film 6 is on the insulating substrate 2 in the gap g, the end faces of the first and second soft magnetic films 3 and 4 facing the gap g, and the following. The nonmagnetic insulating film 5 is formed on a part of the end surface and the upper surface, but it is sufficient if it is formed on at least the end surfaces of the first soft magnetic film 3 and the second soft magnetic film 4. Alternatively, the giant magnetoresistive thin film 6 may be formed first, the gap g may be opened, and then the nonmagnetic insulating film 5 and the first and second soft magnetic films 3 and 4 may be formed.

  In the thin film magnetoresistive element 1A of this example, as shown in FIG. 1, the end portions of the wide portion 3b of the first soft magnetic film 3 and the wide portion 4b of the second soft magnetic film 4 that do not have the nonmagnetic insulating film 5 are provided. This is a terminal portion for signal detection, and detects a magnetic signal in the direction from the first soft magnetic film 3 to the second soft magnetic film 4 through the giant magnetoresistive thin film 6 or in the opposite direction.

  In the thin film magnetoresistive element 1A of this example, since the nonmagnetic insulating film 5 is formed on the upper surfaces of the first and second soft magnetic films 3 and 4, respectively, the giant magnetoresistive thin film 6 is formed from the upper surface of the first soft magnetic film 3. The electric and magnetic paths reaching the upper surface of the second soft magnetic film 4 can be interrupted via the first soft magnetic film 3 and the giant magnetoresistive thin film 6 as shown by the arrows in FIG. Thus, the electric and magnetic paths leading to the second soft magnetic film 4 can be restricted only in the arrangement direction of the first soft magnetic film 3 and the second soft magnetic film 4. Therefore, dispersion of magnetic flux and non-uniformity of magnetic flux path length can be suppressed, and magnetic field sensitivity and linearity can be improved. In the form of FIG. 2B, the nonmagnetic insulating film 5 is formed on the giant magnetoresistive thin film 6. Also in this case, as shown by the arrows in the figure, the electric circuit and the magnetic circuit are restricted, and the same effect can be obtained.

  Hereinafter, a method of manufacturing the thin film magnetoresistive element 1A according to the first embodiment will be described with reference to FIG. FIG. 3 is a flowchart showing a manufacturing procedure of the thin film magnetoresistive element 1A.

  First, a soft magnetic film as a base for the first soft magnetic film 3 and the second soft magnetic film 4 is formed on one surface of the insulating substrate 2 to have a uniform thickness by plating, sputtering, or the like (procedure S1). Next, a photoresist layer is uniformly formed on the soft magnetic film, and a mask for forming the first soft magnetic film and the second soft magnetic film is formed through an exposure process and a development process (step S2). Next, the portion of the soft magnetic film not covered with the photoresist layer is removed by etching, ion milling, or the like, and then the remaining photoresist layer is removed (step S3). As a result, the first soft magnetic film 3 and the second soft magnetic film 4 are formed on one surface of the insulating substrate 2 so as to face each other with a required gap g therebetween. Next, a nonmagnetic insulating film 5 is formed by sputtering (step S4), and a photoresist layer is again formed uniformly on the entire upper surface of the insulating substrate 2 including the upper surfaces of the first soft magnetic film 3 and the second soft magnetic film 4. Then, a mask for forming a nonmagnetic insulating film is formed through the exposure process and the development process (step S5). Next, the portion of the oxide film not covered with the photoresist layer is removed by etching or ion milling, and then the remaining photoresist layer is removed (step S6). Thereby, the nonmagnetic insulating film 5 is laminated on the upper surface of the first soft magnetic film 3 and the upper surface of the second soft magnetic film 4 respectively. Next, the giant magnetoresistive thin film 6 is formed by sputtering (step S7), and after a photoresist layer is uniformly formed on the giant magnetoresistive thin film 6, the giant magnetoresistive thin film 6 is subjected to an exposure process and a development process. Is formed (step S8). Next, the portion of the oxide film not covered with the photoresist layer is removed by etching or ion milling, and then the remaining photoresist layer is removed (step S9). Thus, the thin film magnetoresistive element 1A according to the first embodiment shown in FIGS. 1 and 2 having the giant magnetoresistive thin film 6 in the gap g is obtained.

  According to the manufacturing method of this example, the nonmagnetic insulating film 5 is formed between the upper surface of the first soft magnetic film 3 and the giant magnetoresistive thin film 6 and between the upper surface of the second soft magnetic film 4 and the giant magnetoresistive thin film 6. Since it includes a forming step, an electric circuit and a magnetic circuit between the upper surface of the first soft magnetic film 3 and the giant magnetoresistive thin film 6 and an electric circuit and a magnetic circuit between the upper surface of the second soft magnetic film 4 and the giant magnetoresistive thin film 6 and The magnetic path is interrupted, and the electric path and magnetic path from the first soft magnetic film 3 to the second soft magnetic film 4 through the giant magnetoresistive thin film 6 are arranged in the arrangement direction of the first soft magnetic film 3 and the second soft magnetic film 4. 1A can be manufactured.

  Next, a second embodiment of the thin film magnetoresistive element according to the present invention will be described with reference to FIGS. 4 is a plan view of the thin film magnetoresistive element according to the second embodiment, FIG. 5A is a cross sectional view taken along line BB of FIG. 4, FIG. 6 is a cross sectional view of the thin film magnetoresistive element according to the comparative example, and FIG. Is a table showing specifications of the thin film magnetoresistive element according to the second embodiment and the thin film magnetoresistive element according to the comparative example, and FIG. 8 shows the effect of the thin film magnetoresistive element according to the second embodiment as compared with the comparative example. It is a graph shown by comparison.

  As shown in FIGS. 4 and 5A, the thin film magnetoresistive element 1B of this example includes an insulating substrate 2, a strip-shaped first soft magnetic film 3 formed on the insulating substrate 2, and a first soft magnetic film. A nonmagnetic insulating film 5 formed on the upper surface near one end of the film 3 and a part of the upper surface of the nonmagnetic insulating film 5 through one end surface of the nonmagnetic insulating film 5 and one end surface of the first soft magnetic film 3. The giant magnetoresistive thin film 6 formed on a part of the upper surface of the insulating substrate 1 is formed so that one end in the length direction is in contact with the giant magnetoresistive thin film 6 formed on one end face of the first soft magnetic film 3. The belt-shaped second soft magnetic film 4 is formed.

  The film thickness tg of the giant magnetoresistive thin film 6 is equivalent to the gap length Lg of the thin film magnetoresistive element 1A according to the first embodiment, and can be arbitrarily set as required. By setting the thickness to 0.05 μm or more and less than 1.0 μm, the thin film magnetoresistive element 1B having a gap length Lg of 0.05 μm or more and less than 1.0 μm can be realized. In the example of FIG. 5, the giant magnetoresistive thin film 6 is formed on the upper surface of the insulating substrate 2 from a part of the upper surface of the nonmagnetic insulating film 5 through one end surface of the nonmagnetic insulating film 5 and the first soft magnetic film 3. Although it is formed in a part over a part, it is sufficient if it is formed at least on the end face of the first soft magnetic film 3.

  The second soft magnetic film 4 is formed by sputtering a soft magnetic material having the same quality as that of the first soft magnetic film 3.

  Others are the same as those of the thin film magnetoresistive element 1A according to the first embodiment.

  In the thin film magnetoresistive element 1B of this example, a nonmagnetic insulating film 5 is formed on the upper surface of the first soft magnetic film 3, and the second soft magnetic film 3 is disposed on the end surface side of the first soft magnetic film 3 through the giant magnetoresistive thin film 6. Since the magnetic film 4 is formed, the electric and magnetic paths from the upper surface of the first soft magnetic film 3 to the second soft magnetic film 4 through the giant magnetoresistive thin film 6 can be interrupted, and the first soft magnetic film 3 The electric path and magnetic path from the first to the second soft magnetic film 4 through the giant magnetoresistive thin film 6 can be restricted only in the arrangement direction of the first soft magnetic film 3 and the second soft magnetic film 4. Therefore, the dispersion of the magnetic flux and the non-uniformity of the magnetic flux path length can be suppressed, and the magnetic field sensitivity and the linearity thereof can be improved. Further, when the giant magnetoresistive thin film is sufficiently thinner than the soft magnetic film, for example, when it is 1/5 or less, as shown in FIG. 5B, the first soft magnetic film 3 and the second soft magnetic film 4 are used. The same effect can be obtained even if the heights of the end faces are not matched.

  Further, as shown in FIG. 5, the thin film magnetoresistive element 1 </ b> B of this example has one end of the wide portion 3 b formed in the first soft magnetic film 3 and one end of the wide portion 6 b formed in the second soft magnetic film 4. 1 has a terminal portion for signal detection, and detects a magnetic signal in a direction crossing the giant magnetoresistive thin film 6 in the thickness direction. Therefore, the thin film magnetoresistive element 1B of this example can regulate the gap length Lg between the first soft magnetic film 3 and the second soft magnetic film 4 with the film thickness tg of the giant magnetoresistive thin film 6. There is no manufacturing limitation on the gap length as in the case of forming a giant magnetoresistive thin film in the slit-like gap formed in the soft magnetic film, and the magnetic field sensitivity can be improved by reducing the gap length.

  That is, as shown in FIG. 6, after forming a slit-like gap 203 at the center of a soft magnetic film 202 formed on a substrate 201 by applying a fine processing technique such as ion beam etching, the gap A thin film magnetoresistive element 200 (thin film magnetoresistive element according to a comparative example) in which a giant magnetoresistive thin film 204 is formed by sputtering in 203 has a uniform giant into the gap 202 even when the sputtering conditions are optimized. Since it becomes difficult to form the magnetoresistive thin film 203, it is difficult to make the gap length 0.5 μm or less. On the other hand, the thin film magnetoresistive element 1B of this example can regulate the gap length Lg between the first soft magnetic film 3 and the second soft magnetic film 4 with the film thickness tg of the giant magnetoresistive thin film 6. Therefore, by controlling the film thickness tg of the giant magnetoresistive thin film 6, a thin film magnetoresistive element having a gap length of 0.5 μm or less can be manufactured.

  Therefore, the inventors of the present application, as shown in FIG. 7, have compared the thin film magnetoresistive element 200 according to the comparative example in which the film thickness tg of the giant magnetoresistive thin film 203 is 0.25 μm and the gap length Lg is 0.5 μm, The thin film magnetoresistive element 1B according to the second embodiment in which the film thickness tg of the resistive thin film 5 is 0.25 μm and the gap length Lg is 0.1 μm is manufactured, and the magnetic field sensitivities thereof are compared. As is clear from FIG. 7, the other specifications are the same.

  When the strength of the magnetic field at the center of the gap was measured while changing the magnitude of the external magnetic field Hex, as shown in FIG. 8, the gap with respect to the change in the external magnetic field Hex of the thin film magnetoresistive element 1B according to the second embodiment was measured. The rate of change in the strength of the magnetic field at the center is nearly twice that of the thin film magnetoresistive element 200 according to the comparative example, and the magnetic field sensitivity of the thin film magnetoresistive element 1B according to the second embodiment is increased. Has been demonstrated.

  Further, in the thin film magnetoresistive element 1B of this example, the gap length Lg is regulated by the film thickness tg of the giant magnetoresistive thin film 6 as described above, so that it is not necessary to apply a microfabrication technique as means for forming the gap portion. The manufacturing process of the thin film magnetoresistive element can be simplified, and the cost of the thin film magnetoresistive element can be reduced.

  Hereinafter, the manufacturing method of the thin film magnetoresistive element 1B according to FIG. 5A in the second embodiment will be described with reference to FIG. FIG. 9 is a flowchart showing a manufacturing procedure of the thin film magnetoresistive element 1B.

  First, a soft magnetic film as a base of the first soft magnetic film 3 is formed on one surface of the insulating substrate 2 to have a uniform thickness by plating, sputtering, or the like (step S11). Next, a photoresist layer is uniformly formed on the soft magnetic film, and a mask for forming a first soft magnetic film is formed through an exposure process and a development process (step S12). Next, the portion of the soft magnetic film not covered with the photoresist layer is removed by etching or ion milling, and then the remaining photoresist layer is removed (step S13). As a result, the required first soft magnetic film 3 is formed on one surface of the insulating substrate 2. Next, the nonmagnetic insulating film 5 is formed by sputtering (step S14), and a photoresist layer is uniformly formed again on the entire upper surface of the insulating substrate 2 including the upper surface of the first soft magnetic film 3, and the exposure process and the developing process are performed. Then, a mask for forming a nonmagnetic insulating film is formed (step S15). Next, the portion of the oxide film not covered with the photoresist layer is removed by etching or ion milling, and then the remaining photoresist layer is removed (step S16). Thereby, the nonmagnetic insulating film 5 is laminated on the upper surface of the first soft magnetic film 3. Next, the giant magnetoresistive thin film 6 is formed by sputtering (procedure S17), and then a photoresist layer is uniformly formed on the giant magnetoresistive thin film 6, followed by an exposure process and a development process. Is formed (step S18). Next, the portion not covered with the photoresist layer is removed by etching or ion milling, and then the remaining photoresist layer is removed (step S19). Thus, the giant magnetoresistive thin film 6 is formed on the end face of the first soft magnetic film 3 and the end face of the nonmagnetic insulating film 5. Next, a nonmagnetic insulating film 7 is formed on the insulating substrate 2 by sputtering (step S20), and a portion of the oxide film not covered with the photoresist layer is removed by etching or ion milling. Thereafter, the remaining photoresist layer Is removed (procedure S21). As a result, the nonmagnetic insulating film 7 is laminated on the portion of the insulating substrate 2 in contact with the end face of the giant magnetoresistive thin film 6. Next, a soft magnetic film as a base of the second soft magnetic film 3 is formed on the nonmagnetic insulating film 7 to have a uniform thickness by plating or sputtering (step S22), and a photoresist layer is formed on the soft magnetic film. A mask for forming the second soft magnetic film is formed through the exposure process and the development process (step S23). Next, the portion of the soft magnetic film that is not covered with the photoresist layer is removed by etching, ion milling, or the like, and then the remaining photoresist layer is removed (step S24). Thereby, the thin film magnetoresistive element 1B according to the second embodiment shown in FIGS. 4 and 5 is obtained.

  According to the manufacturing method of this example, since the step of forming the nonmagnetic insulating film 5 between the upper surface of the first soft magnetic film 3 and the giant magnetoresistive thin film 6 is included, giant magnetism is applied from the upper surface of the first soft magnetic film 3. The electric path and magnetic path leading to the second soft magnetic film 4 through the resistive thin film 6 are blocked, and the electric path and magnetic path extending from the first soft magnetic film 3 to the second soft magnetic film 4 via the giant magnetoresistive thin film 6 are blocked. The thin film magnetoresistive element 1B restricted only in the arrangement direction of the first soft magnetic film 3 and the second soft magnetic film 4 can be manufactured.

  Next, a third embodiment of the thin film magnetoresistive element according to the present invention will be described with reference to FIGS. FIG. 10 is a plan view of the thin film magnetoresistive element according to the third embodiment, and FIG. 11 is a cross-sectional view taken along the line CC in FIG.

  As shown in FIGS. 10 and 11, the thin film magnetoresistive element 1 </ b> C of this example includes an insulating substrate 2, a strip-shaped first soft magnetic film 3 formed on the insulating substrate 2, and a first soft magnetic film 3. The giant magnetoresistive thin film 6 formed on the upper surface near one end, the upper surface and end surface of the first soft magnetic film 3, the non-magnetic insulating film 5 formed on the outer peripheral portion and the end surface of the upper surface of the giant magnetoresistive thin film 6, and one end It is composed of a strip-shaped second soft magnetic film 4 formed so that the lower surface of the portion is in contact with the giant magnetoresistive thin film 6 exposed from the nonmagnetic insulating film 5.

  Since the configuration of each part is the same as that of the thin film magnetoresistive element 1B according to the second embodiment except for the laminated structure of the films 3 to 6, the corresponding parts are denoted by the same reference numerals and description thereof is omitted. .

  In the thin film magnetoresistive element 1C of this example, a giant magnetoresistive thin film 6 is formed on the upper surface of the first soft magnetic film 3, and between the end face of the first soft magnetic film 3 and the end face of the second soft magnetic film 4. Since the nonmagnetic insulating film 5 is interposed, the electric path and magnetic path from the end face of the first soft magnetic film 3 to the end face of the second soft magnetic film 4 can be interrupted, and the first soft magnetic film 3 can produce giant magnetism. The electric path and magnetic path reaching the second soft magnetic film 4 through the resistive thin film 6 can be restricted only in the thickness direction of the giant magnetoresistive thin film 6. Therefore, the dispersion of the magnetic flux and the non-uniformity of the magnetic flux path length can be suppressed, and the magnetic field sensitivity and the linearity thereof can be improved. In the thin film magnetoresistive element 1C of this example, the giant magnetoresistive thin film 6 is formed on the upper surface of the first soft magnetic film 3, so that the giant magnetoresistive thin film 6 is formed on the end face of the first soft magnetic film 3. In comparison, the thickness of the giant magnetoresistive thin film 6 can be easily controlled, and the magnetic field sensitivity can be improved from this point. Furthermore, the thin film magnetoresistive element 1C of this example can regulate the gap length Lg between the first soft magnetic film 3 and the second soft magnetic film 4 with the film thickness tg of the giant magnetoresistive thin film 6. There is no manufacturing limitation on the gap length as in the case of forming a giant magnetoresistive thin film in the slit-like gap formed in the soft magnetic film, and the magnetic field sensitivity can be improved by reducing the gap length.

  Hereinafter, a method of manufacturing the thin film magnetoresistive element 1C according to the third embodiment will be described with reference to FIG. FIG. 12 is a flowchart showing a manufacturing procedure of the thin film magnetoresistive element 1C.

  First, an insulating substrate 2 is prepared in which a soft magnetic film serving as a base for the first soft magnetic film 3 is formed on one surface to have a uniform thickness by plating or the like (step S21). Next, a photoresist layer is uniformly formed on the soft magnetic film, and a mask for forming a first soft magnetic film is formed through an exposure process and a development process (step S22). Next, the portion of the soft magnetic film not covered with the photoresist layer is removed by etching, ion milling, or the like, and then the remaining photoresist layer is removed (step S23). As a result, the required first soft magnetic film 3 is formed on one surface of the insulating substrate 2. Next, the giant magnetoresistive thin film 6 is formed by sputtering (step S24), and after a photoresist layer is uniformly formed on the giant magnetoresistive thin film 6, the giant magnetoresistive thin film 6 is subjected to an exposure process and a development process. Is formed (step S25). Next, the portion not covered with the photoresist layer is removed by etching or ion milling, and then the remaining photoresist layer is removed (step S26). Thereby, the giant magnetoresistive thin film 6 is laminated on the upper surface of the first soft magnetic film 3. Next, a photoresist layer is uniformly formed on the entire upper surface of the insulating substrate 2 including the upper surface of the first soft magnetic film 3 and the upper surface of the giant magnetoresistive thin film 6. An opening is formed only from the outer peripheral portion of the upper surface to the end surface of the giant magnetoresistive thin film 6 and the upper surface of the first soft magnetic film 3 and the end surface portion of the first soft magnetic film 3 that follow this. A mask for forming the magnetic insulating film is formed (step S27). Next, the nonmagnetic insulating film 5 is formed by sputtering in the opening of the photoresist layer (procedure S28), and then the remaining photoresist layer is removed (procedure S29). As a result, the first soft magnetic film 3, the giant magnetoresistive thin film 6 and the nonmagnetic insulating film 5 are formed on the required portions of the insulating substrate 2. Next, the second soft magnetic film 4 is formed by sputtering (procedure S30). Thereafter, the soft magnetic film is removed by ion milling, etching, or the like, and the remaining photoresist layer is removed (procedure S31). Next, a photoresist layer is uniformly formed, and a mask for the second soft magnetic film is formed through an exposure process and a development process (step S32). Thereby, the thin film magnetoresistive element 1C according to the third embodiment shown in FIGS. 10 and 11 is obtained.

  According to the manufacturing method of this example, the nonmagnetic property is provided between the upper surface of the giant magnetoresistive thin film 6 and the lower surface of the second soft magnetic film 4 and between the end surface of the first soft magnetic film 3 and the end surface of the second soft magnetic film 4. Since the step of forming the insulating film 5 is included, the electric and magnetic paths from the upper surface of the first soft magnetic film 3 to the second soft magnetic film 4 through the giant magnetoresistive thin film 6 and from the end surface of the first soft magnetic film 3 are included. The electric and magnetic paths directly reaching the second soft magnetic film 4 are interrupted, and the electric and magnetic paths extending from the first soft magnetic film 3 to the second soft magnetic film 4 via the giant magnetoresistive thin film 6 are connected to the giant magnetoresistive thin film 6. The thin film magnetoresistive element 1C restricted only in the film thickness direction can be manufactured.

  FIG. 13 shows a thin film magnetoresistive element 1D according to a fourth embodiment of the present invention. FIG. 13 is a cross-sectional view of a main part of a thin film magnetoresistive element 1D according to the fourth embodiment.

  As shown in FIG. 13, in the thin film magnetoresistive element 1D of this example, the first and second soft magnetic films 3 and 4 are formed on the insulating substrate 2 with a predetermined gap g therebetween, and the first and first soft magnetic films 1 and 4 are formed. The nonmagnetic insulating film 5 is laminated on the upper surface of each of the two soft magnetic films 3 and 4, and the giant magnetoresistive thin film 6 is formed on the end faces of the first and second soft magnetic films 3 and 4 and the end face of the nonmagnetic insulating film 5. The third soft magnetic film 11 is formed through the above.

  Even with this configuration, the same effect as the thin film magnetoresistive element 1A according to the first embodiment can be exhibited. Further, if a hard magnetic film is formed in place of the third soft magnetic film 11, a bias effect can be expected.

  FIG. 14 shows a thin film magnetoresistive element 1E according to the fifth embodiment of the present invention. FIG. 14 is a plan view of an essential part of a thin film magnetoresistive element 1E according to the fifth embodiment.

  As shown in FIG. 14, in the thin film magnetoresistive element 1E of this example, the second soft magnetic film 5 is formed in a cross shape, and the giant magnetoresistive thin film 6 extends in a direction perpendicular to each other about the second soft magnetic film 5. (Not shown), a nonmagnetic insulating film 5 and a first soft magnetic film 3 (not shown) are formed. The laminated structure of the first soft magnetic film 3, the nonmagnetic insulating film 5, the giant magnetoresistive thin film 6, and the second soft magnetic film 4 is the thin film magnetoresistive element 1A, 1B according to the first to third embodiments. , 1C.

  Since the thin film magnetoresistive element 1E of this example can simultaneously detect magnetic fields in two orthogonal directions, it can be used not only as a general magnetic sensor but also as a magnetic sensor for special applications such as a compass. .

  Hereinafter, an embodiment of a magnetic sensor according to the present invention will be described with reference to FIGS. 15 is a plan view of the magnetic sensor according to the embodiment, FIG. 16 is a cross-sectional view of a principal part of a fixed resistance element applied to the magnetic sensor according to the embodiment, and FIG. 17 is an equivalent circuit of the magnetic sensor according to the embodiment. FIG.

  As shown in FIG. 15, the magnetic sensor 21 of this example includes two thin film magnetoresistive elements 1 </ b> A according to the first embodiment on two opposite sides, and includes a fixed resistive element 22 on the other two opposite sides. The terminal 23 is formed at the end of each soft magnetic film 3 and 4 constituting the thin film magnetoresistive element 1A.

  As shown in FIG. 16, the fixed resistance element 22 is formed on an insulating substrate 24, a strip-shaped first nonmagnetic metal film 25 formed on the insulating substrate 24, and an upper surface near one end of the first nonmagnetic metal film 25. The formed nonmagnetic insulating film 26 and a portion extending from a part of the upper surface of the nonmagnetic insulating film 26 to a part of the upper surface of the substrate 24 through one end surfaces of the first nonmagnetic metal film 25 and the nonmagnetic insulating film 26. The formed giant magnetoresistive thin film 27 and the strip-shaped second nonmagnetic metal film 28 formed so that one end in the length direction covers the giant magnetoresistive thin film 27 and does not contact the first nonmagnetic metal film 25. Become.

  Since the magnetic sensor 21 of this example uses the thin film magnetoresistive element 1A according to the first embodiment as a thin film magnetoresistive element, the magnetic field sensitivity is high and the linearity is excellent. Further, the magnetic sensor 21 of this example forms a bridge circuit with two thin film magnetoresistive elements 1A provided on two opposing sides and fixed resistance elements 22 provided on the other two opposing sides. Therefore, high-precision magnetic field detection can be performed by the null method that does not depend on fluctuations in the power supply voltage and on the input impedance or non-linearity of the detector.

That is, as shown in FIG. 17, when the resistance values of the two thin film magnetoresistive elements 1A are R ₁ and R ₃ respectively and the resistance values of the two fixed resistance elements 22 are R ₂ and R ₄ respectively, the input voltage The output voltage Vout with respect to Vin is expressed by the following equation.

As is apparent from this equation, the output voltage Vout of the bridge circuit is determined only by the resistance values R ₁ , R ₂ , R ₃ , R _{4 of} each element and the input voltage Vin, and in an equilibrium state, the output voltage Vout is Since it becomes zero, it becomes possible to detect the magnetic field with high accuracy independent of fluctuations in the power supply voltage and the input impedance or non-linearity of the detector, and a highly practical magnetic sensor can be obtained.

  In the above embodiment, the thin film magnetoresistive element 1A according to the first embodiment is used as the thin film magnetoresistive element. Instead, the thin film magnetoresistive element 1B according to the second embodiment or the third embodiment is used instead. The thin film magnetoresistive element 1C according to the embodiment can also be used. In the embodiment, the fixed resistance element 21 having the first nonmagnetic metal film 25, the nonmagnetic insulating film 26, the giant magnetoresistive thin film 27, and the second nonmagnetic metal film 28 is used. Fixed resistance elements having other configurations can also be used.

It is a top view of the thin film magnetoresistive element concerning the example of the 1st embodiment. It is AA sectional drawing of FIG. It is a flowchart which shows the manufacturing method of the thin film magnetoresistive element which concerns on the example of 1st Embodiment. It is a top view of the thin film magnetoresistive element concerning the example of a 2nd embodiment. It is sectional drawing of the thin film magnetoresistive element which concerns on the example of 2nd Embodiment. It is sectional drawing of the thin film magnetoresistive element which concerns on a comparative example. It is a table | surface figure which shows the specification of the thin film magnetoresistive element which concerns on the example of 2nd Embodiment, and the thin film magnetoresistive element which concerns on a comparative example. It is a graph which shows the effect of the thin film magnetoresistive element which concerns on the example of 2nd Embodiment by comparison with a comparative example. It is a flowchart which shows the manufacturing method of the thin film magnetoresistive element based on the example of 2nd Embodiment. It is a top view of the thin film magnetoresistive element which concerns on the example of 3rd Embodiment. It is CC sectional drawing of FIG. It is a flowchart which shows the manufacturing method of the thin film magnetoresistive element based on the example of 3rd Embodiment. It is principal part sectional drawing of the thin film magnetoresistive element which concerns on the example of 4th Embodiment. It is principal part sectional drawing of the thin film magnetoresistive element which concerns on the example of 5th Embodiment. It is a top view of the magnetic sensor which concerns on the example of embodiment. It is principal part sectional drawing of the fixed resistance element applied to the magnetic sensor which concerns on the embodiment. It is an equivalent circuit diagram of the magnetic sensor according to the embodiment. It is principal part sectional drawing of the thin film magnetoresistive element which concerns on a prior art example.

Explanation of symbols

1A to 1E Thin film magnetoresistive element 2 Insulating substrate 3 First soft magnetic film 4 First soft magnetic film 5 Nonmagnetic insulating film 6 Giant magnetoresistive thin film 11 Third soft magnetic film 21 Magnetic sensor 22 Fixed resistance element 23 Terminal

Claims (4)

A giant magnetoresistive thin film, first and second soft magnetic films having one end electrically and magnetically connected via the giant magnetoresistive thin film, and the first soft magnetic film and the second soft magnetic film. A thin film magnetoresistive element having a nonmagnetic insulating film interposed between at least one of them and the giant magnetoresistive thin film, wherein the first and second soft magnetic films are provided with signal detection terminal portions. In
The nonmagnetic insulating film is formed on an upper surface of the first soft magnetic film formed on an insulating substrate, and the giant magnetoresistive thin film is formed on an upper surface and an end surface of the nonmagnetic insulating film and an end surface of the first soft magnetic film. The nonmagnetic insulating film is formed on the insulating substrate so that one end is in contact with the giant magnetoresistive thin film, and one end is on the end surface of the nonmagnetic insulating film and the first surface on the top surface of the nonmagnetic insulating film. The second soft magnetic film is formed so as to be in contact with the giant magnetoresistive thin film formed on the end face of the soft magnetic film, and the non-magnetic insulating film passes through the giant magnetoresistive thin film from the first soft magnetic film. A thin film magnetoresistive element characterized in that an electric path and a magnetic path leading to a second soft magnetic film are restricted only in an arrangement direction of the first soft magnetic film and the second soft magnetic film. 2. The thin film magnetoresistive element according to claim 1, wherein the giant magnetoresistive thin film is formed of a granular magnetic film in which ferromagnetic fine particles are dispersed in an insulator matrix . The thickness of the giant magnetoresistive thin film formed between the first soft magnetic film and the second soft magnetic film is 0.05 μm or more and less than 1.0 μm . Thin film magnetoresistive element. A giant magnetoresistive thin film, first and second soft magnetic films having one end electrically and magnetically connected via the giant magnetoresistive thin film, and the first soft magnetic film and the second soft magnetic film. A thin film magnetoresistive element having a nonmagnetic insulating film interposed between at least one of them and the giant magnetoresistive thin film, wherein the first and second soft magnetic films are provided with signal detection terminal portions. The nonmagnetic insulating film is formed on the top surface of the first soft magnetic film formed on the insulating substrate, and the giant surface is formed on the top surface and end surface of the nonmagnetic insulating film and the end surface of the first soft magnetic film. A magnetoresistive thin film is formed, and the nonmagnetic insulating film is formed on the insulating substrate so that one end is in contact with the giant magnetoresistive thin film, and one end is on the end surface of the nonmagnetic insulating film on the top surface of the nonmagnetic insulating film. And the giant magnetic resistance formed on the end surface of the first soft magnetic film. The second soft magnetic film is formed in contact with the thin film, and the electric path and magnetic path from the first soft magnetic film to the second soft magnetic film via the giant magnetoresistive thin film are formed by the nonmagnetic insulating film. A bridge having two thin film magnetoresistive elements that are restricted only in the arrangement direction of the first soft magnetic film and the second soft magnetic film on two opposing sides and a fixed resistive element on the other two opposing sides A magnetic sensor using a thin film magnetoresistive element comprising a circuit.

Images