JP2017083280A - Semiconductor device and magnetic sensor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor device and a magnetic sensor device that can suppress a manufacturing cost.SOLUTION: A semiconductor device 1 schematically includes: a substrate 2; a conductor 3 on the substrate 2, that generates a bias magnetic field 30 by a current I flowing in the conductor; an insulator film 4 covering the conductor 3; and an MR sensor unit 5, that receives an application of the bias magnetic field 30 through the insulator film 4 and outputs a change in the bias magnetic field 30 associated with approach of a detection target 7, as an electric signal, as shown in Figs. 1(a) and 1(b).SELECTED DRAWING: Figure 1

Description

  The present invention relates to a semiconductor device and a magnetic sensor device.

  Conventionally, a substrate, a thin film magnet that generates a bias magnetic field, a magnetoresistive element to which a bias magnetic field is applied, and an output of the magnetoresistive element are formed on the substrate by a Co—Pt thin film that is a hard magnetic film layer. There is known a magnetic sensor in which a circuit portion to be processed is formed on the same chip (see, for example, Patent Document 1).

  This magnetic sensor is small because the magnetoresistive element, the output processing circuit, and the thin film magnet are formed on the same chip.

JP-A-5-264701

  However, the conventional magnetic sensor has a problem that the manufacturing cost increases because a thin film magnet must be formed using a material such as Pt or Nd that is more expensive than a material such as wiring formed on the substrate.

  Accordingly, an object of the present invention is to provide a semiconductor device and a magnetic sensor device that can reduce manufacturing costs.

  According to one embodiment of the present invention, a substrate, a conductor formed on the substrate and generating a bias magnetic field by a current flowing through the substrate, an insulating film covering the conductor, and a bias magnetic field is applied through the insulating film so that a detection target approaches And a magnetic sensor unit that outputs a change in the bias magnetic field accompanying the above as an electrical signal.

  According to the present invention, the manufacturing cost can be suppressed.

FIG. 1A is a cross-sectional view showing an example of the configuration of the semiconductor device according to the first embodiment, and FIG. 1B is a schematic view showing an example of the arrangement of MR sensor portions and conductors. . FIG. 2A is a schematic diagram illustrating an example of a bias magnetic field generated by the conductor of the semiconductor device according to the first embodiment, and FIG. 2B is a diagram illustrating the Hall sensor unit and the conductor according to the modification. FIG. 2C is a schematic diagram illustrating an example of a bias magnetic field generated by two conductors according to a modified example, and FIG. 2D is an MR diagram according to the modified example. It is the schematic which shows an example of arrangement | positioning of a sensor part and two conductors. FIG. 3A is a cross-sectional view showing an example of the configuration of the magnetic sensor device according to the second embodiment, and FIGS. 3B and 3C are examples of modifications of the magnetic sensor device. FIG.

(Summary of embodiment)
A semiconductor device according to an embodiment includes a substrate, a conductor formed on the substrate and generating a bias magnetic field by a current flowing through the substrate, an insulating film covering the conductor, and a bias magnetic field applied through the insulating film, And a magnetic sensor unit that outputs a change in the bias magnetic field accompanying the approach as an electric signal.

  The strength H of the bias magnetic field formed by the current flowing through the conductor is proportional to the current I flowing through the conductor and inversely proportional to the distance r from the conductor as known as Ampere's law, but depends on the material of the conductor. do not do. Since a semiconductor device can apply a bias magnetic field to a magnetic sensor unit by passing a current through a conductor, it is not necessary to use an expensive material to form a conductor, compared to the case of forming a thin film magnet, Manufacturing cost can be suppressed.

[First embodiment]
(Outline of the semiconductor device 1)
FIG. 1A is a cross-sectional view showing an example of the configuration of the semiconductor device according to the first embodiment, and FIG. 1B shows an example of the arrangement of MR (Magneto Resistive) sensor units and conductors. FIG. FIG. 2A is a schematic diagram illustrating an example of a bias magnetic field generated by the conductor of the semiconductor device according to the first embodiment, and FIG. 2B is a diagram illustrating the Hall sensor unit and the conductor according to the modification. FIG. 2C is a schematic diagram illustrating an example of a bias magnetic field generated by two conductors according to a modified example, and FIG. 2D is an MR diagram according to the modified example. It is the schematic which shows an example of arrangement | positioning of a sensor part and two conductors. In the above sectional view, hatching is not performed to illustrate the bias magnetic field. Note that, in each drawing according to the embodiment described below, the ratio between figures may be different from the actual ratio.

  For example, as illustrated in FIG. 1A, the semiconductor device 1 detects a change in the bias magnetic field 30 due to the approach of the detection target 7. As an example, the detection object 7 is a counter magnet disposed on a buckle of a seat belt device mounted on a vehicle. The detection object 7 is configured to move in the direction of the semiconductor device 1 when the tongue plate is inserted and away from the semiconductor device 1 when the tongue plate is discharged from the buckle. The direction of this movement is, for example, from the back side of the paper surface of FIG. The semiconductor device 1 is not limited to the arrangement with respect to the buckle, but can be used for a non-contact switch or the like.

  As shown in FIG. 1A, the semiconductor device 1 includes a substrate 2, a conductor 3 that is formed on the substrate 2 and generates a bias magnetic field 30 by a current I flowing therethrough, an insulating film 4 that covers the conductor 3, An MR sensor unit 5 as a magnetic sensor unit that is applied with a bias magnetic field 30 through the insulating film 4 and outputs a change in the bias magnetic field 30 accompanying the approach of the detection target 7 as an electric signal is schematically configured. .

  When the semiconductor device 1 is disposed on the buckle, as an example, it is assumed that a mechanical switch is turned on after the tongue plate is inserted and a current flows through the conductor 3.

(Configuration of substrate 2)
The substrate 2 is a semiconductor substrate such as a silicon substrate, for example. On this substrate 2, for example, in addition to the conductor 3 and the MR sensor unit 5, an amplification circuit that amplifies the electrical signal output from the MR sensor unit 5, and whether a tongue plate is mounted based on the amplified electrical signal A control circuit or the like is formed. This control circuit is electrically connected to the conductor 3 and the MR sensor unit 5. Then, the control circuit supplies the current I to the conductor 3 and determines whether the tongue plate is attached based on the electric signal output from the MR sensor unit 5. Therefore, the semiconductor device 1 is an IC (Integrated Circuit) chip in which the MR sensor unit 5, the control circuit, and the like are integrated. As an example, this control circuit is electrically connected to an external terminal that is electrically connected to a vehicle control unit or the like of the vehicle, and exchanges information and signals with the vehicle control unit and the like.

(Configuration of conductor 3)
The conductor 3 is formed by a semiconductor process such as sputtering using a conductive metal material such as Cu or Al. For example, as shown in FIG. 1B, the conductor 3 has an angle of 45 ° with the first MR element 51 of the MR sensor section 5 to be described later and the magnetic sensing section 50 a of the fourth MR element 54. Is arranged. That is, by using this configuration, the angle θ between the magnetic sensing portion 50a and the bias magnetic field 30 formed by the conductor 3 is 45 ° as shown in FIG.

  As shown in FIG. 2A, the conductor 3 has a rectangular cross section. Accordingly, the bias magnetic field 30 formed by the current I flowing through the conductor 3 becomes a concentric magnetic field surrounding the conductor 3 as shown in FIG. Since the current I flows toward the back of the sheet of FIG. 2A, the bias magnetic field 30 is a magnetic field that rotates clockwise.

  As shown in FIG. 2 (a), the conductor 3 of the present embodiment has a rectangular shape with a rectangular cross section, so that the parallel region 31, the parallel region 32, It has a vertical region 33 and a vertical region 34.

  The parallel region 31 and the parallel region 32 are regions in which the horizontal component of the bias magnetic field 30 is larger than the vertical component on the paper surface of FIG. The parallel region 31 is a region above the conductor 3, and the parallel region 32 is a region below the conductor 3. This region is suitable for disposing a magnetic sensor unit that detects a change in the bias magnetic field 30 applied in a direction substantially parallel to the magnetosensitive surface.

  The vertical region 33 and the vertical region 34 are regions in which the vertical component of the bias magnetic field 30 is larger than the horizontal component on the paper surface of FIG. The vertical region 33 is a region on the left side of the conductor 3, and the vertical region 34 is a region on the right side of the conductor 3. This region is suitable for arranging a magnetic sensor unit that detects a change in the bias magnetic field 30 applied in a direction substantially perpendicular to the magnetosensitive surface.

  Since the magnetic sensor unit of the present embodiment is the MR sensor unit 5, it is arranged in at least one of the parallel region 31 and the parallel region 32. Since the conductor 3 is disposed on the substrate 2, the MR sensor unit 5 is disposed in the parallel region 31. That is, the conductor 3 is formed between the substrate 2 and the MR sensor unit 5.

  The conductor 3 has a horizontally elongated rectangular shape so as to form a magnetic field closer to an ellipse than a magnetic field close to a circle in order to make the horizontal component of the bias magnetic field 30 more parallel to the magnetosensitive surface 50 of the MR element. Have.

  As a modification, when the magnetic sensor is a Hall sensor unit 5 a made of a Hall element, the Hall sensor unit 5 a is arranged in at least one of the vertical region 33 and the vertical region 34. FIG. 2B shows a modification in which the hall sensor unit 5 a is arranged in the vertical region 33.

  A semiconductor device 1 shown in FIG. 2B includes a substrate 2, a conductor 3 formed on the substrate 2, a hall sensor unit 5a formed on the substrate 2, and an insulation covering the conductor 3 and the hall sensor unit 5a. And a membrane 4a.

  Since the Hall sensor unit 5a detects a change in the bias magnetic field 30 applied in a direction substantially perpendicular to the magnetosensitive surface, the conductor 3 is formed in the same layer as the Hall sensor unit 5a. Since the conductor 3 is formed in the same layer as the hall sensor portion 5a, the conductor 3 can be formed in the process of forming the hall sensor portion 5a. Furthermore, when the conductor 3 is formed of the same material as the wiring that electrically connects the hall sensor unit 5a and the control circuit, the conductor 3 can be formed in the process of forming the wiring.

  As a modification, the number of conductors 3 is not limited to one, and may be constituted by a plurality of conductors as shown in FIGS. 2 (c) and 2 (d). As shown in FIGS. 2 (c) and 2 (d), when two conductors 3 are arranged in parallel, when the distance between the conductors is appropriate and the current I flows in the same direction, the magnetic field between the conductors. Cancel each other in opposite directions, and a bias magnetic field 30 is generated so as to surround the two conductors 3.

(Configuration of insulating film 4)
The insulating film 4 is formed by a semiconductor process such as a CVD (Chemical Vapor Deposition) method using, for example, SiO ₂ or SiN. As an example, the insulating film 4 of the present embodiment is composed of a first insulating film 40 and a second insulating film 41 as shown in FIG.

  The first insulating film 40 is an insulating film formed after the conductor 3 is formed. The second insulating film 41 is an insulating film formed after the MR sensor unit 5 is formed.

(Configuration of MR sensor unit 5)
As shown in FIG. 1B, the MR sensor unit 5 is roughly configured to include MR elements 51 to 54. In the MR sensor unit 5, a bridge circuit is formed by the MR elements 51 to 54.

  For example, the MR elements 51 to 54 are formed by a semiconductor process such as sputtering using a ferromagnetic metal such as Ni, Fe, or Co. The resistance values of the MR elements 51 to 54 to which no magnetic field is applied are equal.

  The MR elements 51 to 54 are formed above the conductor 3 after the conductor 3 and the first insulating film 40 are formed, for example.

One end of the MR element 51 is electrically connected to one end of the MR element 52. The other end of the MR element 51 is electrically connected to a control circuit, for example, and supplied with a reference voltage _VCC . The other end of the MR element 52 is electrically connected to, for example, a ground circuit. The MR element 51 and the MR element 52 constitute a half bridge circuit.

One end of the MR element 53 is electrically connected to one end of the MR element 54. The other end of the MR element 53 is electrically connected to a control circuit, for example, and supplied with a reference voltage _VCC . The other end of the MR element 54 is electrically connected to, for example, a ground circuit. The MR element 53 and the MR element 54 constitute a half bridge circuit.

MR sensor unit 5 includes a middle point potential _{V 1} of the half-bridge circuit of the MR element 51 and MR element 52, the midpoint potential _{V 2} of the half-bridge circuit of the MR element 53 and MR element 54, the differential voltage (= V ₁ −V ₂ ) is output as an electrical signal.

  As shown in FIG. 1B, each of the MR elements 51 to 54 has a magnetic sensing portion 50a arranged in parallel at equal intervals, and a connecting portion 50b for electrically connecting the magnetic sensing portion 50a. Yes. The magnetosensitive part 50 a is a part where the magnetoresistance value changes according to the direction of the bias magnetic field 30. Further, as an example, the connection portion 50b is a portion that is so small that the change in the magnetoresistance value is negligible compared to the magnetic sensing portion 50a. Note that the connection portion 50b may be formed using, for example, a conductive member whose magnetic resistance value does not change.

  As shown in FIG. 1B, the MR element 51 is arranged such that the magnetic sensitive part 50 a has an angle of 45 ° with respect to the bias magnetic field 30. The MR element 52 is disposed so that the MR element 51 is rotated by 90 °, and the magnetic sensing portion 50 a is at an angle of 45 ° with respect to the bias magnetic field 30. The MR element 53 and the MR element 54 are arranged so as to be rotationally symmetric by rotating the MR element 51 and the MR element 52 by 180 °. Therefore, the magnetic sensitive part 50 a of the MR element 51 to the MR element 54 has an angle of 45 ° with respect to the bias magnetic field 30.

  When only the bias magnetic field 30 acts on the MR sensor unit 5, the angle between the magnetic sensing unit 50a and the bias magnetic field 30 is 45 °, so that the resistance values of the MR elements 51 to 54 are the same, and the difference therebetween The voltage becomes zero.

  Therefore, when the tongue plate is not attached, that is, when the detection target 7 is sufficiently separated from the MR sensor unit 5, the electrical signal output from the MR sensor unit 5 becomes zero. For example, the MR sensor unit 5 is corrected so that the electrical signal output from the MR sensor unit 5 becomes zero when the detection target 7 is sufficiently separated from the MR sensor unit 5.

  When the tongue plate is mounted, that is, when the detection target 7 is positioned above the MR sensor unit 5, the direction of the bias magnetic field 30 changes, so that the magnetic resistance of the MR elements 51 to 54 changes and the electric signal is changed. Is no longer zero, and the connected control circuit determines the attachment of the tongue plate.

(Effects of the first embodiment)
The semiconductor device 1 according to the present embodiment can reduce the manufacturing cost. Specifically, since the semiconductor device 1 can apply the bias magnetic field 30 to the MR sensor unit 5 by flowing the current I through the conductor 3, a thin film magnet using a material higher than the material of the conductor 3 is formed. Compared with the case where it does, manufacturing cost can be suppressed using an inexpensive material for the conductor 3.

  In the semiconductor device 1, the conductor 3 can be formed of the same material as the wiring used for the amplifier circuit and the control circuit. Therefore, the material is common as compared with the material forming the thin film magnet that is different from the wiring and the MR element. As a result, the manufacturing cost can be reduced. The conductor 3 can be formed in the process of forming the wiring if the material is common. However, since the thin film magnet is formed of a material different from that of the wiring and the MR element, it must be formed in a separate process. Therefore, the semiconductor device 1 is reduced in the number of processes and the manufacturing cost is suppressed.

  Since the semiconductor device 1 does not require a bias magnet for applying a bias magnetic field from the outside, the manufacturing cost is suppressed as compared with the case where a bias magnet more expensive than the conductor 3 is used. Further, the semiconductor device 1 can be reduced in size because a bias magnet is not required on the outside.

[Second Embodiment]
The second embodiment is different from the first embodiment in that the conductor is located outside the magnetic sensor element in which the magnetic sensor is sealed.

  FIG. 3A is a cross-sectional view showing an example of the configuration of the magnetic sensor device according to the second embodiment, and FIGS. 3B and 3C are examples of modifications of the magnetic sensor device. FIG. In the embodiments described below, parts having the same functions and configurations as those of the first embodiment are denoted by the same reference numerals as those of the first embodiment, and description thereof is omitted.

  As shown in FIG. 3A, the magnetic sensor device 9 is applied with a bias magnetic field 30, and outputs a change in the bias magnetic field 30 accompanying the approach of the detection target 7 as an electric signal, and a magnetic sensor element. And a conductor 3 that generates a bias magnetic field 30 to be applied to 90 by a current I flowing therethrough.

  As shown in FIG. 3A, the magnetic sensor device 9 has a conductor 3 when the magnetic sensor element 90 detects a change in the bias magnetic field 30 applied in a direction substantially parallel to the magnetic sensitive surface 91. Is disposed on the opposite surface (back surface 93) side of the surface (front surface 92) of the magnetic sensor element 90 to which the detection target 7 approaches.

  The magnetic sensor element 90 includes MR elements 51 to 54, and a bridge circuit is formed by the MR elements 51 to 54. The MR elements 51 to 54 are sealed with a sealing agent such as an epoxy resin, for example.

  The magnetic sensor element 90 may be a bare chip composed of the MR elements 51 to 54, or may be an IC chip including an amplifier circuit and a control circuit connected to the MR elements 51 to 54.

  The conductor 3 is attached to the back surface 93 of the magnetic sensor element 90 with an adhesive, for example. As a modification, the magnetic sensor device 9 may have a configuration in which a plurality of conductors are attached to the magnetic sensor element 90 as shown in FIG. In this case, as shown in FIG. 3B, the conductor 3 may have a circular cross section or an electric wire whose periphery is covered with an insulator. The conductor 3 may not be attached to the magnetic sensor element 90, and may be disposed so as to be in contact with the magnetic sensor element 90 or in the vicinity thereof.

  The conductor 3 may be formed on the surface of the printed wiring board, for example, or may be disposed on the printed wiring board. In this case, the magnetic sensor element 90 is disposed on the conductor 3 and attached to the printed wiring board.

  As another modification, the magnetic sensor device 9 detects a change in the bias magnetic field 30 to which the magnetic sensor element 90 is applied in a direction substantially perpendicular to the magnetosensitive surface 91 as shown in FIG. In this case, the conductor 3 is disposed on at least one of the side surface 94 and the side surface 95 of the magnetic sensor element 90. FIG. 3B shows a case where the conductor 3 is disposed on the side surface 94 and the side surface 95 as an example.

  The magnetic sensor element 90 has a Hall element, and the Hall element is sealed with a sealing agent such as an epoxy resin.

  The conductor 3 disposed on the side surface 94 and the side surface 95 of the magnetic sensor element 90 generates a bias magnetic field 30 that penetrates the magnetically sensitive surface 91 of the Hall element in a substantially vertical direction.

(Effect of the second embodiment)
The magnetic sensor device 9 according to the present embodiment can apply the bias magnetic field 30 to the magnetic sensor element 90 by the conductor 3, so that the manufacturing cost can be reduced as compared with the case where the bias magnetic field is generated using the bias magnet. be able to.

  Since the magnetic sensor device 9 generates the bias magnetic field 30 using the conductor 3, the magnetic sensor device 9 can be reduced in size as compared with the case where a bias magnet is used.

  In the above-described embodiment, the MR sensor unit 5 is disposed in the parallel region 31 and the parallel region 32, and the Hall sensor unit 5a is disposed in the vertical region 33 and the vertical region 34. The MR sensor unit 5 may be arranged in the vertical region 33 or the vertical region 34 so that the Hall sensor unit 5a may be arranged in the parallel region 31 or the parallel region 32 so as to be perpendicular to the magnetic sensitive surface.

  The MR sensor unit 5 is composed of four MR elements. However, the present invention is not limited to this, and a plurality of four MR elements forming a bridge circuit may be arranged adjacent to each other. Two MR circuits may be formed by two MR elements.

  As mentioned above, although some embodiment and modification of this invention were demonstrated, these embodiment and modification are only examples, and do not limit the invention based on a claim. These novel embodiments and modifications can be implemented in various other forms, and various omissions, replacements, changes, and the like can be made without departing from the scope of the present invention. In addition, not all combinations of features described in these embodiments and modifications are necessarily essential to the means for solving the problems of the invention. Further, these embodiments and modifications are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 1 ... Semiconductor device, 2 ... Board | substrate, 3 ... Conductor, 4 ... Insulating film, 4a ... Insulating film, 5 ... MR sensor part, 5a ... Hall sensor part, 7 ... Detection object, 9 ... Magnetic sensor apparatus, 30 ... Bias magnetic field 31 ... Parallel region 32 ... Parallel region 33 ... Vertical region 34 ... Vertical region 40 ... First insulating film 41 ... Second insulating film 50 ... Magnetic sensing surface 50a ... Magnetic sensing portion 50b ... Connection part, 51-54 ... MR element, 90 ... Magnetic sensor element, 91 ... Magnetic sensing surface, 92 ... Front surface, 93 ... Back, 94 ... Side, 95 ... Side

Claims (6)

A substrate,
A conductor formed on the substrate and generating a bias magnetic field by a current flowing through the substrate;
An insulating film covering the conductor;
A magnetic sensor unit to which the bias magnetic field is applied via the insulating film and outputs a change in the bias magnetic field as the detection target approaches, as an electrical signal;
A semiconductor device comprising: When the magnetic sensor unit detects a change in the bias magnetic field applied in a direction substantially parallel to the magnetosensitive surface,
The conductor is formed between the substrate and the magnetic sensor unit;
The semiconductor device according to claim 1. When the magnetic sensor unit detects a change in the bias magnetic field applied in a direction substantially perpendicular to the magnetosensitive surface,
The conductor is formed in the same layer as the magnetic sensor unit;
The semiconductor device according to claim 1. A magnetic sensor element to which a bias magnetic field is applied and outputs a change in the bias magnetic field as the detection target approaches, as an electrical signal;
A conductor generated by a current flowing in the bias magnetic field applied to the magnetic sensor element;
A magnetic sensor device comprising: When the magnetic sensor element detects a change in the bias magnetic field applied in a direction substantially parallel to the magnetosensitive surface,
The conductor is disposed on the opposite side of the surface of the magnetic sensor element to which the detection object approaches,
The magnetic sensor device according to claim 4. When the magnetic sensor element detects a change in the bias magnetic field applied in a direction substantially perpendicular to the magnetosensitive surface,
The conductor is disposed on a side surface of the magnetic sensor element;
The magnetic sensor device according to claim 4.

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