Magnetic Sensors

Abstract

In the present invention, a first magnetic layer (10) is such that parts thereof are a first magnetoresistive element (120a) and a second magnetoresistive element (130a). An electroconductive layer (20) is provided on portions of the first magnetic layer (10) other than the abovementioned parts. An insulation layer (30) is provided on the electroconductive layer (20) and on the abovementioned parts of the first magnetic layer (10). A resist layer (40) is provided on the insulation layer (30) and has a ring shape. A seed layer (50) is provided on the resist layer (40) and on the insulation layer (30) in a portion located in a first region (R1) surrounded by the resist layer (40). A second magnetic layer (60) is provided on the seed layer (50) and covers the second magnetoresistive element (130a). A dummy electrode (160), which is a part of the electroconductive layer (20), is located in the first region (R1). A through hole (30h) is formed in the insulation layer (30) located on the dummy electrode (160) in the first region (R1). In the through hole (30h), the second magnetic layer (60) is connected, via the seed layer (50), to the dummy electrode (160).

Description

[Technical field]

[0001] The present invention relates to a magnetic sensor. [Background technology]

[0002] A prior art document disclosing the configuration of a magnetic sensor is International Publication No. 2019 / 111765 (Patent Document 1). The magnetic sensor described in Patent Document 1 includes a magnetic sensing element, an insulating layer covering the magnetic sensing element, a first conductor located on the insulating layer, a first magnetic member located on the first conductor and covering the first conductor when viewed from a direction perpendicular to the insulating layer, and a member provided along a part of the first conductor and made of a different material from the first conductor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2019 / 111765 Summary of the Invention [Problem to be solved by the invention]

[0004] If the adhesion between the insulating layer and the first conductive portion is low, there is a possibility that the first magnetic member will peel off from the insulating layer together with the first conductive portion.

[0005] The present invention has been made in consideration of the above problems, and aims to provide a magnetic sensor that can suppress peeling of a magnetic layer provided above an insulating layer from the insulating layer. [Means for solving the problem]

[0006] The magnetic sensor according to the present invention includes a first magnetic layer, a conductive layer, an insulating layer, a resist layer, a seed layer, and a second magnetic layer. The first magnetic layer is provided on a main surface of a substrate, and a part of the first magnetic layer becomes a first magnetoresistance element and a second magnetoresistance element. The conductive layer is provided on a portion of the first magnetic layer other than the part. The insulating layer is provided on the part of the first magnetic layer and on the conductive layer. The resist layer is provided on the insulating layer and has a ring shape when viewed from a direction perpendicular to the main surface. The seed layer is provided on the insulating layer and on the resist layer in a portion located in a first region surrounded by the resist layer when viewed from a direction perpendicular to the main surface. The second magnetic layer is provided on the seed layer and covers the second magnetoresistance element when viewed from a direction perpendicular to the main surface. A dummy electrode, which is a part of the conductive layer, is located in the first region. A through hole is formed in the insulating layer located on the dummy electrode in the first region. The second magnetic layer is connected to the dummy electrode in the through hole via the seed layer. Effect of the Invention

[0007] According to the present invention, it is possible to suppress peeling of the magnetic layer provided above the insulating layer from the insulating layer. [Brief description of the drawings]

[0008] [Figure 1] 1 is a plan view showing a configuration of a magnetic sensor according to an embodiment of the present invention; [Diagram 2] 2 is a cross-sectional view of the magnetic sensor of FIG. 1 as viewed from the direction of the arrows along line II-II. [Diagram 3] 1 is an equivalent circuit diagram of a magnetic sensor according to an embodiment of the present invention. [Figure 4] 1 is a partial cross-sectional view showing a state in which an insulating layer is formed so as to cover a main surface of a semiconductor substrate. [Diagram 5] 11 is a partial cross-sectional view showing a state in which a through hole is formed in an insulating layer located above a dummy electrode. FIG. [Figure 6] FIG. 2 is a partial cross-sectional view showing a state in which a resist layer is formed on an insulating layer. [Figure 7]10 is a partial cross-sectional view showing a state in which a seed layer is formed on a portion of an insulating layer and a portion of a resist layer located in a first region surrounded by a resist layer. FIG. [Figure 8] FIG. 4 is a partial plan view showing the configuration of a magnetic sensor according to a first modified example of the embodiment of the present invention. [Figure 9] 13 is a chart showing anisotropy of the detection sensitivity of a magnetic field of the magnetic sensor according to the first modified example of the embodiment of the present invention. [Figure 10] FIG. 11 is a partial plan view showing the configuration of a magnetic sensor according to a second modified example of the embodiment of the present invention. [Figure 11] 13 is a chart showing anisotropy of the detection sensitivity of a magnetic field of a magnetic sensor according to a second modified example of the embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, a magnetic sensor according to an embodiment of the present invention will be described with reference to the drawings. In the following description of the embodiment, the same or corresponding parts in the drawings are given the same reference characters and their description will not be repeated.

[0010] Fig. 1 is a plan view showing the configuration of a magnetic sensor according to an embodiment of the present invention. Fig. 2 is a cross-sectional view of the magnetic sensor of Fig. 1 as seen from the direction of the arrows II-II. Fig. 3 is an equivalent circuit diagram of the magnetic sensor according to an embodiment of the present invention. In Fig. 1, the edge of a second magnetic layer, which will be described later, is indicated by a dotted line.

[0011] 1 and 2, a magnetic sensor 1 according to an embodiment of the present invention includes a first magnetic layer 10, a conductive layer 20, an insulating layer 30, a resist layer 40, a seed layer 50, and a second magnetic layer 60. The magnetic sensor 1 further includes a semiconductor substrate 110.

[0012] The semiconductor substrate 110 is composed of a base portion 111 made of a semiconductor such as Si, and an insulating film 112 formed on the base portion 111 and made of SiO2, Si3N4, or the like.

[0013] The first magnetic layer 10 is provided on the main surface of the semiconductor substrate 110. The first magnetic layer 10 is made of a magnetic material such as an alloy containing Ni and Fe. The first magnetic layer 10 has a thickness of, for example, 0.04 μm. The first magnetic layer 10 is patterned by an ion milling method or the like. Parts of the first magnetic layer 10 become the first magnetoresistance elements 120a, 120b and the second magnetoresistance elements 130a, 130b.

[0014] The conductive layer 20 is provided on the portion of the first magnetic layer 10 other than the above-mentioned portion. The conductive layer 20 is made of a conductive material such as Au or Al. The conductive layer 20 is patterned by wet etching or the like. The conductive layer 20 becomes a terminal, a wiring, or a dummy electrode, which will be described later. A Ti layer 21 is provided directly on the conductive layer 20.

[0015] The insulating layer 30 is provided on the above-mentioned portion of the first magnetic layer 10 and on the conductive layer 20. The insulating layer 30 is made of an insulating material such as SiO2. The insulating layer 30 covers the first magnetoresistance elements 120a, 120b and the second magnetoresistance elements 130a, 130b. The insulating layer 30 does not cover the portions of the conductive layer 20 that will become terminals.

[0016] The resist layer 40 is provided on the insulating layer 30, and has an annular shape when viewed from a direction perpendicular to the main surface of the semiconductor substrate 110. In this embodiment, the resist layer 40 has an annular shape when viewed from a direction perpendicular to the main surface of the semiconductor substrate 110. The resist layer 40 covers the first magnetoresistance elements 120a, 120b and the second magnetoresistance elements 130a, 130b, but it is sufficient that the resist layer 40 covers at least the second magnetoresistance elements 130a, 130b.

[0017] The seed layer 50 is provided on the insulating layer 30 and the resist layer 40 in a portion located in the first region R1 surrounded by the resist layer 40 when viewed from a direction perpendicular to the main surface of the semiconductor substrate 110. In this embodiment, the seed layer 50 is composed of a layer containing titanium (Ti) and a layer containing gold (Au) located on the layer containing titanium (Ti). However, the configuration of the seed layer 50 is not limited to the above, and may include at least one layer of iron (Fe), molybdenum (Mo), tantalum (Ta), platinum (Pt), and copper (Cu). As a method for forming the seed layer 50, patterning using a resist or the like can be used. In this embodiment, the seed layer 50 has an octagonal shape when viewed from a direction perpendicular to the main surface of the semiconductor substrate 110, but may have a circular shape or a polygonal shape other than an octagonal shape. The seed layer 50 has a thickness of, for example, 0.5 μm.

[0018] The second magnetic layer 60 is provided on the seed layer 50 and covers the second magnetoresistance element 130a when viewed from a direction perpendicular to the main surface of the semiconductor substrate 110. In this embodiment, the second magnetic layer 60 has an octagonal shape when viewed from a direction perpendicular to the main surface of the semiconductor substrate 110, but may have a circular shape or a polygonal shape other than an octagonal shape. The maximum thickness of the second magnetic layer 60 is preferably 2.0 μm or less. The second magnetic layer 60 can be formed by patterning using a resist or the like.

[0019] As shown in Fig. 1 and Fig. 3, the magnetic sensor 1 according to an embodiment of the present invention includes a first magnetic resistance element 120a and a second magnetic resistance element 130a, and a first magnetic resistance element 120b and a second magnetic resistance element 130b, which are electrically connected to each other by wiring to form a Wheatstone bridge type bridge circuit. In this embodiment, the magnetic sensor 1 includes two sets of the first magnetic resistance element and the second magnetic resistance element, but is not limited to this, and may include at least one set of the first magnetic resistance element and the second magnetic resistance element. When the magnetic sensor 1 includes only one set of the first magnetic resistance element and the second magnetic resistance element, specifically, when the magnetic sensor 1 includes only the first magnetic resistance element 120a and the second magnetic resistance element 130a, a half bridge circuit is formed.

[0020] Each of the first magnetoresistance elements 120a, 120b and the second magnetoresistance elements 130a, 130b is an anisotropic magnetoresistance (AMR) element. Each of the first magnetoresistance elements 120a, 120b and the second magnetoresistance elements 130a, 130b may be a magnetoresistance element such as a giant magnetoresistance (GMR) element, a tunnel magnetoresistance (TMR) element, a ballistic magnetoresistance (BMR) element, or a colossal magnetoresistance (CMR) element, instead of an AMR element.

[0021] 1 and 2, the second magnetoresistance element 130a is covered by the second magnetic layer 60 and therefore serves as a so-called fixed resistor that hardly detects a magnetic field in a direction perpendicular to the main surface of the semiconductor substrate 110 (vertical magnetic field) and a magnetic field in a direction parallel to the main surface of the semiconductor substrate 110 (horizontal magnetic field). The first magnetoresistance element 120a is not covered by the second magnetic layer 60 and therefore serves as a so-called magnetosensitive resistor whose electric resistance value changes when an external magnetic field is applied. That is, the first magnetoresistance element 120a functions as a magnetosensitive element, and the second magnetoresistance element 130a does not function as a magnetosensitive element.

[0022] Similarly, the second magnetoresistance element 130b is covered by the second magnetic layer 60 and therefore serves as a so-called fixed resistor, which detects almost no magnetic field in a direction perpendicular to the main surface of the semiconductor substrate 110 (vertical magnetic field) or a magnetic field in a direction parallel to the main surface of the semiconductor substrate 110 (horizontal magnetic field). The first magnetoresistance element 120b is not covered by the second magnetic layer 60 and therefore serves as a so-called magnetosensitive resistor, whose electrical resistance value changes when an external magnetic field is applied. That is, the first magnetoresistance element 120b functions as a magnetosensitive element, and the second magnetoresistance element 130b does not function as a magnetosensitive element.

[0023] 1 and 3, the first magnetoresistance elements 120a, 120b and the second magnetoresistance elements 130a, 130b are electrically connected to each other by wiring provided on the semiconductor substrate 110. Specifically, the first magnetoresistance element 120a and the second magnetoresistance element 130a are connected in series by the wiring 146. The first magnetoresistance element 120b and the second magnetoresistance element 130b are connected in series by the wiring 150.

[0024] On the semiconductor substrate 110, a midpoint terminal (V+) 140, a midpoint terminal (V-) 141, a power supply terminal (Vcc) 142, a ground terminal (Gnd) 143, and an output terminal (Out) 144 are further provided.

[0025] Each of the first magnetic resistance element 120a and the second magnetic resistance element 130b is connected to a midpoint terminal (V+) 140. Specifically, the first magnetic resistance element 120a and the midpoint terminal (V+) 140 are connected by a wiring 145, and the second magnetic resistance element 130b and the midpoint terminal (V+) 140 are connected by a wiring 152.

[0026] Each of the first magnetic resistance element 120b and the second magnetic resistance element 130a is connected to a midpoint terminal (V-) 141. Specifically, the first magnetic resistance element 120b and the midpoint terminal (V-) 141 are connected by a wiring 149, and the second magnetic resistance element 130a and the midpoint terminal (V-) 141 are connected by a wiring 148.

[0027] The wiring 146 is connected to a power supply terminal (Vcc) 142 to which a current is input. The wiring 150 is connected to a ground terminal (Gnd) 143.

[0028] 1 and 2, each of the wirings 145, 146, 148, 149, 150, 152, the midpoint terminal (V+) 140, the midpoint terminal (V-) 141, the power supply terminal (Vcc) 142, the ground terminal (Gnd) 143, and the output terminal (Out) 144 is formed of a conductive layer 20. The conductive layer 20 in the portions that will become the midpoint terminal (V+) 140, the midpoint terminal (V-) 141, the power supply terminal (Vcc) 142, the ground terminal (Gnd) 143, and the output terminal (Out) 144 is exposed and not covered with the insulating layer 30. The conductive layer 20 in the portions that will become the wirings 145, 146, 148, 149, 150, 152 is covered with the insulating layer 30.

[0029] Since the magnetic sensor 1 has the above circuit configuration, a potential difference that depends on the strength of the external magnetic field is generated between the midpoint terminal (V+) 140 and the midpoint terminal (V-) 141. When this potential difference exceeds a preset detection level, a signal is output from the output terminal (Out) 144.

[0030] As shown in FIG. 1, in this embodiment, the portion of the first magnetic layer 10 that becomes the first magnetoresistance elements 120a, 120b is formed along approximately the entire edge of the second magnetic layer 60 so as to surround the second magnetic layer 60 when viewed in a direction perpendicular to the main surface of the semiconductor substrate 110, thereby providing isotropic magnetic field detection sensitivity.

[0031] 1 and 2, a dummy electrode 160, which is a part of the conductive layer 20, is located in the first region R1. The dummy electrode 160 is not electrically connected to any of the midpoint terminal (V+) 140, the midpoint terminal (V-) 141, the power supply terminal (Vcc) 142, the ground terminal (Gnd) 143, and the output terminal (Out) 144, and is at a floating potential. In this embodiment, the dummy electrode 160 has a circular shape when viewed from a direction perpendicular to the main surface of the semiconductor substrate 110, but may have a polygonal shape.

[0032] 2, in the first region R1, a through hole 30h is formed in the insulating layer 30 located on the dummy electrode 160. The second magnetic layer 60 is connected to the dummy electrode 160 through the seed layer 50 in the through hole 30h.

[0033] Here, a process for connecting the second magnetic layer 60 and the dummy electrode 160 will be described. Fig. 4 is a partial cross-sectional view showing a state in which an insulating layer is formed so as to cover the main surface of a semiconductor substrate. As shown in Fig. 4, a portion of the insulating layer 30 located on the dummy electrode 160 has a convex shape following the shape of the dummy electrode 160.

[0034] Fig. 5 is a partial cross-sectional view showing a state where a through hole is formed in the insulating layer located on the dummy electrode. As shown in Fig. 5, a through hole 30h is formed by removing a part of the insulating layer 30 and the Ti layer 21 located on the dummy electrode 160 by etching. As a result, a part of the upper surface of the dummy electrode 160 is exposed.

[0035] 6 is a partial cross-sectional view showing a state in which a resist layer is formed on an insulating layer. As shown in FIG 6, a resist layer 40 is formed on the insulating layer 30 so as to surround the insulating layer 30 located on the dummy electrode 160 and to cover at least the second magnetoresistance element 130a.

[0036] 7 is a partial cross-sectional view showing a state in which a seed layer is formed on the insulating layer and the resist layer in a portion located in the first region surrounded by the resist layer. As shown in FIG. 7, a seed layer 50 is formed on the insulating layer 30 in a portion located in the first region R1 surrounded by the resist layer 40 and on the resist layer 40. The seed layer 50 formed in the through hole 30h is in direct contact with the dummy electrode 160.

[0037] 2, a second magnetic layer 60 is formed on the seed layer 50. The second magnetic layer 60 formed in the through hole 30h is connected to the dummy electrode 160 via the seed layer 50.

[0038] In the magnetic sensor 1 according to this embodiment, the second magnetic layer 60 is connected to the dummy electrode 160 via the seed layer 50. Since the bonding strength between the dummy electrode 160 and the seed layer 50 is higher than the bonding strength between the insulating layer 30 and the seed layer 50, the second magnetic layer 60 provided above the insulating layer 30 can be prevented from peeling off from the insulating layer 30 by connecting the second magnetic layer 60 to the dummy electrode 160 via the seed layer 50. In other words, the second magnetic layer 60 is connected to the dummy electrode 160 via the seed layer 50, and thus the second magnetic layer 60 can be prevented from peeling off from the insulating layer 30 together with the seed layer 50.

[0039] In the magnetic sensor 1 according to the present embodiment, the magnetic field detection sensitivity is isotropic, but the magnetic field detection sensitivity may be anisotropic. A magnetic sensor according to a modified example having anisotropic magnetic field detection sensitivity will be described below.

[0040] The magnetic sensor according to the first variant of one embodiment of the present invention differs from the magnetic sensor 1 according to one embodiment of the present invention only in the shape of the portion of the first magnetic layer that becomes the first magnetoresistance element, and therefore the configuration that is similar to that of the magnetic sensor 1 according to one embodiment of the present invention will not be described repeatedly.

[0041] Fig. 8 is a partial plan view showing the configuration of a magnetic sensor according to a first modified example of an embodiment of the present invention. As shown in Fig. 8, in the magnetic sensor according to the first modified example of an embodiment of the present invention, a portion of the first magnetic layer 10 that becomes the first magnetoresistance element 220a is formed along only a part of the entire periphery of the edge of the second magnetic layer 60 so as to surround the second magnetic layer 60 when viewed from a direction perpendicular to the main surface of the semiconductor substrate 110.

[0042] Specifically, the portion of the first magnetic layer 10 that becomes the first magnetoresistance element 220a is formed along only approximately 3 / 4 of the circumference surrounding the second magnetic layer 60, excluding the 1 / 4 circumference portion located in the lower right corner of Figure 8 at the edge of the second magnetic layer 60, when viewed from a direction perpendicular to the main surface of the semiconductor substrate 110.

[0043] Fig. 9 is a chart showing the anisotropy of the magnetic field detection sensitivity of the magnetic sensor according to the first modified example of one embodiment of the present invention. Fig. 9 shows the relationship between the magnetic field strength (mT) at which the magnetic sensor changes from an OFF state to an ON state and the angular direction in which the magnetic field acts on the magnetic sensor. The data of the magnetic sensor 1 according to one embodiment of the present invention is shown by a dotted line, and the data of the magnetic sensor according to the first modified example is shown by a solid line.

[0044] 9, the magnetic sensor according to the first modification had the lowest sensitivity to the magnetic fields acting from the 135° and 315° directions. As in the magnetic sensor according to the first modification, the portion of the first magnetic layer 10 that becomes the first magnetoresistance element 220a is formed along only a part of the entire circumference of the edge of the second magnetic layer 60 so as to surround the second magnetic layer 60 when viewed from a direction perpendicular to the main surface of the semiconductor substrate 110, and this allows the detection sensitivity of the magnetic sensor to have anisotropy.

[0045] The magnetic sensor according to the second variant of one embodiment of the present invention differs from the magnetic sensor 1 according to one embodiment of the present invention mainly in the shape of the portion of the first magnetic layer that becomes the first magnetic resistance element and the arrangement of the first magnetic layer, and therefore the configuration that is similar to that of the magnetic sensor 1 according to one embodiment of the present invention will not be described repeatedly.

[0046] Fig. 10 is a partial plan view showing the configuration of a magnetic sensor according to a second modified example of an embodiment of the present invention. As shown in Fig. 10, in the magnetic sensor according to the second modified example of an embodiment of the present invention, a portion of the first magnetic layer 10 that becomes the first magnetoresistance element 320a is formed along only a part of the entire periphery of the edge of the second magnetic layer 60 so as to surround the second magnetic layer 60 when viewed from a direction perpendicular to the main surface of the semiconductor substrate 110.

[0047] Specifically, the portion of the first magnetic layer 10 that becomes the first magnetoresistance element 320a is formed along only approximately 5 / 8 of the circumference surrounding the second magnetic layer 60, excluding the 3 / 8 circumference portion located at the bottom in Figure 10 at the edge of the second magnetic layer 60, when viewed from a direction perpendicular to the main surface of the semiconductor substrate 110.

[0048] Fig. 11 is a chart showing the anisotropy of the magnetic field detection sensitivity of the magnetic sensor according to the second modified example of one embodiment of the present invention. Fig. 11 shows the relationship between the magnetic field strength (mT) at which the magnetic sensor changes from an OFF state to an ON state and the angular direction in which the magnetic field acts on the magnetic sensor. The data of the magnetic sensor 1 according to one embodiment of the present invention is shown by a dotted line, and the data of the magnetic sensor according to the second modified example is shown by a solid line.

[0049] 11, the magnetic sensor according to the second modification had the lowest sensitivity to the magnetic fields acting from the 0° and 180° directions. As in the magnetic sensor according to the second modification, the portion of the first magnetic layer 10 that becomes the first magnetoresistance element 320a is formed along only a part of the entire circumference of the edge of the second magnetic layer 60 so as to surround the second magnetic layer 60 when viewed from a direction perpendicular to the main surface of the semiconductor substrate 110, and this allows the detection sensitivity of the magnetic sensor to have anisotropy.

[0050] Moreover, one vertex P1 of the octagonal shape of the second magnetic layer 60 is disposed in an angular position where the detection sensitivity of the magnetic field is low due to anisotropy. In the magnetic sensor according to the second modification, one vertex P1 of the octagonal shape of the second magnetic layer 60 is disposed in a position in the 0° direction, and the other vertex P2 of the octagonal shape of the second magnetic layer 60 is disposed in a position in the 180° direction.

[0051] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0052] 1 magnetic sensor, 10 first magnetic layer, 20 conductive layer, 21 Ti layer, 30 insulating layer, 30h through hole, 40 resist layer, 50 seed layer, 60 second magnetic layer, 110 semiconductor substrate, 111 base, 112 insulating film, 120a, 120b, 220a, 320a first magnetoresistance element, 130a, 130b second magnetoresistance element, 145, 146, 148, 149, 150, 152 wiring, 160 dummy electrode, P1, P2 vertex, R1 first region.

Claims

1. a first magnetic layer provided on a major surface of the substrate, a portion of which becomes the first magnetoresistance element and the second magnetoresistance element; a conductive layer provided on a portion other than the portion of the first magnetic layer; an insulating layer provided on the portion of the first magnetic layer and on the conductive layer; a resist layer provided on the insulating layer and having an annular shape when viewed in a direction perpendicular to the main surface; a seed layer provided on the insulating layer and the resist layer in a portion located in a first region surrounded by the resist layer when viewed from a direction perpendicular to the main surface; a second magnetic layer provided on the seed layer and covering the second magnetoresistance element when viewed in a direction perpendicular to the main surface; a dummy electrode that is a part of the conductive layer is located within the first region; a through hole is formed in the insulating layer located above the dummy electrode in the first region, The second magnetic layer is connected to the dummy electrode through the seed layer in the through hole.

2. 2. The magnetic sensor of claim 1, wherein the portion of the first magnetic layer that becomes the first magnetoresistance element is formed along only a portion of the entire circumference of the edge of the second magnetic layer so as to surround the second magnetic layer when viewed from a direction perpendicular to the main surface, thereby providing anisotropy in magnetic field detection sensitivity.

3. the second magnetic layer has a polygonal shape when viewed in a direction perpendicular to the main surface, The magnetic sensor according to claim 2 , wherein one vertex of the polygonal shape is disposed at a position in an angular direction in which the anisotropy reduces detection sensitivity of a magnetic field.

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