JP2015141121A - magnetic sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a configuration that suppresses erroneous detection of a magnetic field applied in a direction other than a direction orthogonal to both a direction in which a current flows and a direction in which a potential difference is generated in a magnetic sensor having a hall element.SOLUTION: A magnetic sensor 1 includes a first semiconductor substrate 2, a second semiconductor substrate 3, a hall element 4 disposed on a flat surface 2a of the first semiconductor substrate 2, and a junction 5 joining the first semiconductor substrate 2 and the second semiconductor substrates 3. The magnetic sensor 1 is configured such that a magnetic shield 6 for surrounding a periphery of the hall element 4 when viewed from a normal line to the flat surface 2a of the first semiconductor substrate 2 is disposed between the flat surface 2a of the first semiconductor substrate 2 and a surface 3a of the second semiconductor substrate 3.

Description

  The present invention relates to a magnetic sensor having a Hall element that detects the intensity of a magnetic field using the Hall effect.

  Conventionally, a magnetic sensor having a Hall element that detects the intensity of a magnetic field using the Hall effect (for example, a magnetic sensor described in Patent Document 1) is known. The Hall effect is a phenomenon in which when a magnetic field perpendicular to the direction of current flow is applied to a current flow, a potential difference occurs in the direction perpendicular to both the direction of current flow and the direction of magnetic field application. It is.

  The magnetic sensor described in Patent Document 1 is configured to include a Hall element and a signal processing circuit that performs signal processing such as converting a magnetic field detected by the Hall element into an electric signal, and uses the Hall effect. The magnetic field generated by the magnet and the magnetic field generated by the current are converted into electrical signals and output. Thus, the magnetic sensor detects a magnetic field applied in a direction orthogonal to both the direction of current flow and the direction of potential difference.

  In the magnetic sensor described in Patent Document 1, a Hall element is provided on one surface of a semiconductor substrate, and this Hall element detects a so-called horizontal Hall element, that is, a magnetic field perpendicular to one surface of the semiconductor substrate. It is configured as a Hall element. In this magnetic sensor, graphene is used as the Hall element.

JP 2012-215498 A

  However, a magnetic sensor using a lateral Hall element such as the magnetic sensor described in Patent Document 1 erroneously detects a magnetic field applied in a direction other than the direction perpendicular to both the direction of current flow and the direction of potential difference. May end up. That is, for example, a magnetic field applied in a direction in which current flows or a direction in which a potential difference occurs may be detected. In particular, in the magnetic sensor described in Patent Document 1, the Hall element is made of graphene, and graphene has a high magnetic field detection sensitivity. Therefore, such erroneous detection is particularly likely to occur.

  In view of the above points, the present invention provides a configuration in which a magnetic sensor having a Hall element is less likely to erroneously detect a magnetic field applied in a direction other than the direction perpendicular to both the direction of current flow and the direction of potential difference. With the goal.

  To achieve the above object, according to the first aspect of the present invention, a first semiconductor substrate (2) having a flat surface (2a) and a second semiconductor having one surface (3a) directed to the flat surface of the first semiconductor substrate. A substrate (3), a Hall element (4) provided on the plane of the first semiconductor substrate and detecting a magnetic field perpendicular to the plane of the first semiconductor substrate using the Hall effect, the plane of the first semiconductor substrate, and the second A bonding portion (5) provided between one surface of the semiconductor substrate and bonding the first semiconductor substrate and the second semiconductor substrate; and a hole in at least one of the first semiconductor substrate and the second semiconductor substrate. A magnetic sensor provided with a signal processing circuit for converting a magnetic field detected by an element into an electrical signal, has the following characteristics.

  That is, the space between the plane of the first semiconductor substrate and one surface of the second semiconductor substrate surrounds the periphery of the Hall element when viewed from the direction of the perpendicular to the plane of the first semiconductor substrate, and includes a soft magnetic material. The magnetic shield part (6) is provided, and the Hall element is sealed by the first semiconductor substrate, the second semiconductor substrate, and at least one of the bonding part and the magnetic shield part.

  Therefore, the magnetic field applied to the Hall element is not affected by the magnetic field perpendicular to the plane of the first semiconductor substrate, but the magnetic field applied in the linear direction including the plane of the first semiconductor substrate is reduced. . That is, the influence of a magnetic field other than a magnetic field (a magnetic field perpendicular to the plane of the first semiconductor substrate) applied in a direction orthogonal to both the direction in which a current that is a magnetic field to be detected as a Hall element and the direction in which a potential difference occurs is small. Become. Thereby, the effect that it becomes difficult to produce a misdetection is acquired.

  In addition, the code | symbol in the bracket | parenthesis of each means described in this column and the claim shows the correspondence with the specific means as described in embodiment mentioned later.

1 is a perspective view showing a magnetic sensor according to a first embodiment of the present invention. It is a perspective view which shows the sensor chip part (part comprised by the 1st semiconductor substrate, Hall element, etc.) in the magnetic sensor shown in FIG. It is a figure which shows the plane structure of the sensor chip part (part comprised by the 1st semiconductor substrate, the Hall element, etc.) in the magnetic sensor shown in FIG. It is a figure which shows the cross-sectional structure of the sensor chip part (part comprised by the 1st semiconductor substrate, the Hall element, etc.) in the magnetic sensor shown in FIG. It is a figure which shows the planar structure of the sensor chip part (part comprised by the 1st semiconductor substrate, the Hall element, etc.) in the magnetic sensor which concerns on 2nd Embodiment of this invention. It is a figure which shows the plane structure of the sensor chip part (part comprised by the 1st semiconductor substrate, the Hall element, etc.) in the magnetic sensor which concerns on other embodiment of this invention. It is a figure which shows the planar structure of the sensor chip part (part comprised by the 1st semiconductor substrate, the Hall element, etc.) in the magnetic sensor which concerns on another embodiment of this invention. It is a figure which shows the planar structure of the sensor chip part (part comprised by the 1st semiconductor substrate, the Hall element, etc.) in the magnetic sensor which concerns on another embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other will be described with the same reference numerals.

(First embodiment)
A magnetic sensor 1 according to a first embodiment of the present invention will be described with reference to FIGS. FIG. 2 shows the sensor chip portion (portion constituted by the first semiconductor substrate 2, the Hall element 4 and the like) in the magnetic sensor 1 shown in FIG. 1 upside down from FIG. .

  As shown in FIGS. 1 and 2, the magnetic sensor 1 includes a first semiconductor substrate 2, a second semiconductor substrate 3, a Hall element 4 provided on the plane 2 a of the first semiconductor substrate 2, It has the junction part 5 which joins the semiconductor substrates 2 and 3. As shown in FIG. 2 and FIG. 3, the magnetic sensor 1 is formed from a direction perpendicular to the plane 2 a of the first semiconductor substrate 2 between the plane 2 a of the first semiconductor substrate 2 and one surface 3 a of the second semiconductor substrate 3. A magnetic shield portion 6 configured to surround the periphery of the Hall element 4 when viewed is provided.

  The magnetic sensor 1 uses the Hall effect to convert a magnetic field generated by a magnet or a magnetic field generated by a current into an electrical signal and output the electrical signal. As a result, the magnetic sensor 1 has a direction (arrow Bz in FIG. 1) that is orthogonal to both the direction of current flow (see arrow Bx in FIG. 1) and the direction in which a potential difference occurs (see arrow By in FIG. 1). ) Is detected. The magnetic sensor 1 is applied as a current sensor, for example.

  The first semiconductor substrate 2 is a thin plate-like semiconductor substrate made of a semiconductor such as Si (silicon). As shown in FIGS. 2 and 3, in the magnetic sensor 1 according to the present embodiment, the first semiconductor substrate 2 has a plane 2a, and the Hall element 4 is provided on the plane 2a. As shown in FIG. 4, in the magnetic sensor 1 according to the present embodiment, the silicon oxide film 7 is formed on the surface of the first semiconductor substrate 2, and the plane 2 a is formed as the surface of the silicon oxide film 7. It has been configured.

  The Hall element 4 is a horizontal Hall element, that is, a Hall element that detects a magnetic field perpendicular to the plane 2a of the first semiconductor substrate 2 (see arrow Bz in FIGS. 1 and 4). The configuration of the Hall element 4 is not particularly limited as long as it is a known Hall element, but the magnetic sensor 1 according to the present embodiment employs graphene that is an element with high magnetic field detection sensitivity.

  As shown in FIG. 3, here, the Hall element 4 includes four electrodes 4 a, 4 b, 4 c that are orthogonal to each other at four corners of a rectangular semiconductor region 21 a formed on the plane 2 a of the first semiconductor substrate 2. 4d is provided. The semiconductor region 21a is electrically connected to these electrodes 4a to 4d via electrodes (wirings) (not shown) disposed in the semiconductor region 21a. In the magnetic sensor 1 according to the present embodiment, a potential detection electrode 21b for detecting the substrate potential of the first semiconductor substrate 2 is provided on the plane 2a of the first semiconductor substrate 2.

  Here, for example, when a constant current flows from the electrode 4b to the electrode 4d, a current mainly including a component parallel to the plane 2a of the first semiconductor substrate 2 is allowed to flow. At this time, when a magnetic field perpendicular to the plane 2a is applied to the current (see arrow Bz in FIG. 4), the magnetic field is applied between the electrodes 4a and 4c due to the Hall effect described above. Hall voltage is generated. Then, by detecting the generated Hall voltage signal, a magnetic field perpendicular to the plane 2a of the first semiconductor substrate 2 is obtained. In the Hall element 4, a Hall voltage signal can be detected by the electrodes 4b and 4d by passing a current through the electrodes 4a and 4c. By utilizing such electrode replacement, the offset voltage (unbalanced voltage) generated in the Hall element 4 can be canceled.

  Similar to the first semiconductor substrate 2, the second semiconductor substrate 3 is a thin semiconductor substrate made of a semiconductor such as Si (silicon). As shown in FIGS. 1 and 2, the second semiconductor substrate 3 has one surface 3 a directed to the plane 2 a of the first semiconductor substrate 2, and the plane 2 a of the first semiconductor substrate 2 and the second semiconductor substrate 3 It is joined to the second semiconductor substrate 3 via a joint part 5 described later provided between the one surface 3a. The second semiconductor substrate 3 is provided with a signal processing circuit (not shown) for converting the magnetic field detected by the Hall element 4 into an electric signal. This signal processing circuit may be provided on the first semiconductor substrate 2.

  As shown in FIGS. 1 and 2, the bonding portion 5 is provided between the plane 2 a of the first semiconductor substrate 2 and one surface 3 a of the second semiconductor substrate 3, and the first semiconductor substrate 2 and the second semiconductor substrate 3. It is a member which joins. The material of the joint 5 is not particularly limited, and can be made of, for example, a material containing Si or a soft magnetic material. Note that the bonding portion 5 is formed by a film forming method such as sputtering, vapor deposition, or CVD.

  As shown in FIGS. 2 and 3, in the magnetic sensor 1 according to the present embodiment, the junction 5 continuously surrounds the Hall element 4 when viewed from the direction of the perpendicular to the plane 2 a of the first semiconductor substrate 2. Is formed. That is, the junction 5 is formed so as to surround the entire circumference of the Hall element 4 (hereinafter referred to as “continuously” as meaning “around the entire circumference”). Further, as shown in FIG. 3, the bonding portion 5 is formed along the outer edge of the flat surface 2 a of the first semiconductor substrate 2. In the magnetic sensor 1 according to this embodiment, the Hall element 4 made of graphene is sealed by the first semiconductor substrate 2, the second semiconductor substrate 3, and the bonding portion 5 (for example, vacuum sealing, inert gas sealing). Has been stopped). The term “sealing” as used herein means that the Hall element 4 is isolated from the outside so as not to touch the outside air. Since the Hall element 4 is sealed in this way, in the magnetic sensor 1 according to the present embodiment, a change in characteristics of the Hall element 4 in particular with time is reduced, and detection can be performed with high accuracy. In the magnetic sensor 1 according to the present embodiment, a mold sealing structure in which a mold resin is provided around the first semiconductor substrate 2 and the second semiconductor substrate 3 may be used.

  Here, in the magnetic sensor 1 according to the present embodiment, as described above, the magnetic shield portion 6 is provided between the flat surface 2 a of the first semiconductor substrate 2 and the one surface 3 a of the second semiconductor substrate 3. As shown in FIGS. 2 and 3, the magnetic shield 6 is formed so as to continuously surround the periphery of the Hall element 4 when viewed from the direction of the perpendicular to the plane 2 a of the first semiconductor substrate 2. As shown in FIG. 3, the magnetic shield part 6 is formed in a region surrounded by the joint part 5 when viewed from the direction of the perpendicular to the plane 2 a of the first semiconductor substrate 2. It is set as the structure formed continuously along the external shape. The material of the magnetic shield portion 6 is not particularly limited as long as it includes a material having a high magnetic permeability (soft magnetic material). Here, a soft magnetic material such as NiFe (nickel iron), permalloy, and ferrite is used. It consists of The magnetic shield portion 6 is formed as a film by sputtering, vapor deposition, CVD, or the like, and then formed by a method such as photolithography, etching, or lift-off.

  In the magnetic sensor 1 according to the present embodiment, the magnetic shield part 6 described above is provided, and the Hall element 4 is surrounded by the magnetic shield part 6 made of a material containing a soft magnetic material. The influence of the external magnetic field on the enclosed area on the internal magnetic field is reduced. That is, when viewed from the direction of the perpendicular to the plane 2a, the magnetic shield portion 6 is formed on the plane 2a so as to surround the Hall element 4, so that the plane 2a out of the magnetic field applied to the Hall element 4 can be obtained. However, the magnetic field applied in the linear direction (Bx, By) including the plane 2a is small. That is, the influence of a magnetic field other than a magnetic field (magnetic field perpendicular to the plane 2a) applied in a direction orthogonal to both the direction of current flow and the direction of potential difference, which is a magnetic field to be detected as the Hall element 4, is reduced. For this reason, in the magnetic sensor 1 which concerns on this embodiment, the effect that it becomes difficult to produce a misdetection is acquired. In the magnetic sensor 1 according to the present embodiment, since the magnetic shield portion 6 is continuously formed, this effect is particularly great.

  In the magnetic sensor 1 according to this embodiment, the Hall element 4 is sealed by the first and second semiconductor substrates 2 and 3 and the bonding portion 5 as described above. It may be configured to be sealed by 2, 3 and the magnetic shield part 6.

  As described above, in the magnetic sensor 1 according to the present embodiment, the Hall element 4 is seen between the plane 2a of the first semiconductor substrate 2 and the one surface 3a of the second semiconductor substrate 3 when viewed from the direction of the perpendicular to the plane 2a. Is provided with a magnetic shield portion 6 configured to surround the periphery of the magnetic field.

  For this reason, in the magnetic sensor 1 according to the present embodiment, the magnetic field applied to the Hall element 4 has no effect on the magnetic field perpendicular to the plane 2a, but is applied in the linear direction including the plane 2a. Becomes smaller. That is, the influence of a magnetic field other than a magnetic field (magnetic field perpendicular to the plane 2a) applied in a direction orthogonal to both the direction of current flow and the direction of potential difference, which is a magnetic field to be detected as the Hall element 4, is reduced. Thereby, in the magnetic sensor 1 which concerns on this embodiment, the effect that it becomes difficult to produce a misdetection is acquired.

  In particular, in the magnetic sensor 1 according to the present embodiment, the magnetic shield portion 6 is formed continuously. For this reason, in the magnetic sensor 1 which concerns on this embodiment, the effect which becomes difficult to produce the erroneous detection mentioned above becomes especially large.

(Second Embodiment)
A second embodiment of the present invention will be described with reference to FIG. In this embodiment, in the first embodiment, the magnetic shield portion 6 is configured as a wiring that electrically connects the Hall element 4 and the signal processing circuit. Others are the same as those in the first embodiment, and therefore only the parts different from the first embodiment will be described.

  As shown in FIG. 5, in the magnetic sensor 1 according to the present embodiment, the magnetic shield portion 6 has a rectangular outer shape that surrounds the periphery of the Hall element 4 when viewed from the direction perpendicular to the plane 2 a of the first semiconductor substrate 2. It is set as the structure formed intermittently along. Here, as an example, two quadrangles are used, and one quadrangle (hereinafter referred to as an outer quadrangle) surrounds the other quadrangle (hereinafter referred to as an inner quadrangle). And in the magnetic sensor 1 which concerns on this embodiment, the junction part 5 is provided surrounding these two squares (an outer side square, an inner side square).

  As shown in FIG. 5, the magnetic shield part 6 formed along the outer shape of the outer quadrangle is constituted by two parts (see reference numerals 6a and 6b in FIG. 5). Moreover, the magnetic shield part 6 formed along the outer shape of the inner quadrangle is constituted by four parts (see reference numerals 6c, 6d, 6e, and 6f in FIG. 5). Four (6a to 6d) of these six portions 6a to 6f are electrically connected to any one of the electrodes 4a, 4b, 4c, and 4d of the Hall element 4, and are connected to the second semiconductor substrate 3. It is electrically connected to the formed signal processing circuit. The remaining two (6e, 6f) of the six parts 6a to 6f are used as a potential detection electrode 21b for detecting the substrate potential of the first semiconductor substrate 2. Thus, in the magnetic sensor 1 according to the present embodiment, the magnetic shield 6 is used as a wiring that electrically connects the Hall element 4 and the signal processing circuit.

  In the present embodiment, since the magnetic shield portion 6 is used as a wiring as described above, it is particularly preferable that the magnetic shield portion 6 is made of a Ni (nickel) -based material that is a material having a low contact resistance. preferable.

  As described above, in the magnetic sensor 1 according to this embodiment, the magnetic shield portion 6 is configured as a wiring that electrically connects the Hall element 4 and the signal processing circuit. For this reason, in the magnetic sensor 1 according to the present embodiment, the number of parts is small, and the manufacture becomes easy.

(Other embodiments)
The present invention is not limited to the embodiment described above, and can be appropriately changed within the scope described in the claims.

  For example, in the first and second embodiments, the junction 5 is formed along the outer edge of the plane 2a of the first semiconductor substrate 2 when viewed from the direction of the perpendicular to the plane 2a of the first semiconductor substrate 2, and the magnetic shield unit 6 was formed in a region surrounded by the joint 5. However, as shown in FIGS. 6 and 7, the magnetic shield portion 6 is formed along the outer edge of the flat surface 2 a of the first semiconductor substrate 2, and the joint portion 5 is formed in a region surrounded by the magnetic shield portion 6. May be.

  Further, in the first and second embodiments, the joint portion 5, which is a separate member from the magnetic shield portion 6, is provided, but the magnetic shield portion 6 and the joint portion 5 may be the same. That is, the magnetic shield part 6 may be configured by the joint part 5. For example, as shown in FIG. 8, in the first embodiment, the first semiconductor substrate 2 and the second semiconductor substrate 3 are interposed via the magnetic shield part 6. It is good also as a structure joined together. That is, here, the Hall element 4 is sealed by the first semiconductor substrate 2, the second semiconductor substrate 3, and the magnetic shield portion 6. Here, the magnetic shield part 6 is formed along the outer edge of the flat surface 2 a of the first semiconductor substrate 2.

2 First semiconductor substrate 2a Plane of first semiconductor substrate 3 Second semiconductor substrate 3a One surface of second semiconductor substrate 4 Hall element 5 Junction part 6 Magnetic shield part 7 Silicon oxide film

Claims (4)

A first semiconductor substrate (2) having a plane (2a);
A second semiconductor substrate (3) having one surface (3a) directed to the plane of the first semiconductor substrate;
A Hall element (4) provided on a plane of the first semiconductor substrate and detecting a magnetic field perpendicular to the plane of the first semiconductor substrate by using a Hall effect;
A bonding portion (5) provided between the plane of the first semiconductor substrate and one surface of the second semiconductor substrate and bonding the first semiconductor substrate and the second semiconductor substrate;
A magnetic sensor provided with a signal processing circuit for converting a magnetic field detected by the Hall element into an electrical signal in at least one of the first semiconductor substrate and the second semiconductor substrate,
A structure between the plane of the first semiconductor substrate and one surface of the second semiconductor substrate surrounds the periphery of the Hall element when viewed from a direction perpendicular to the plane of the first semiconductor substrate, and includes a soft magnetic material. Magnetic shield part (6) is provided,
The Hall element is configured to be sealed by the first semiconductor substrate, the second semiconductor substrate, and at least one of the bonding portion and the magnetic shield portion.   2. The magnetic shield portion according to claim 1, wherein the magnetic shield portion is formed so as to surround the circumference of the Hall element over the entire circumference when viewed from a direction perpendicular to the plane of the first semiconductor substrate. Magnetic sensor.   The magnetic sensor according to claim 1, wherein the magnetic shield part is configured as a wiring that electrically connects the Hall element and the signal processing circuit.   The magnetic sensor according to claim 1, wherein the magnetic shield portion is configured by the joint portion.

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