JP2012037379A - Semiconductor apparatus with current detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To highly accurately detect a current with simple configuration of a semiconductor apparatus including a sensor for detecting the current using a magnetoresistance effector.SOLUTION: A semiconductor apparatus includes: a substrate on which a semiconductor circuit is formed; a first wiring member disposed over the substrate; a vertical wiring member erected on the first wiring member; a second wiring member connected to the vertical wiring member and installed in parallel with the first wiring member; a first magnetoelectric transducer disposed while facing the vertical wiring member; a second magnetoelectric transducer opposing the first magnetoelectric transducer with the vertical wiring member therebetween; a first device wiring for connecting the first magnetoelectric transducer and the second magnetoelectric transducer in series; and a first amplifier circuit to which a midpoint of the first device wiring is inputted.

Description

  The present invention relates to a semiconductor device, and more particularly to a semiconductor device provided with a sensor that detects a current using a magnetoresistive element.

  In addition to the Hall element, a magnetoresistive effect element is known as a magnetoelectric conversion element that detects a magnetic field applied from the outside. The magnetoresistive element includes an AMR (Anisotropic Magneto-Resistance) element using a metal magnetoresistive effect, a GMR (Giant Magneto-Resistance) element using a giant magnetoresistive effect, and a TMR (Tunnel) using a tunnel magnetoresistive effect. Magneto-Resistance) element. In particular, GMR elements and TMR elements that can obtain a larger MR ratio than others are drawing attention.

  Patent Document 1 discloses a GMR element and a TMR element having a spin valve structure. A magnetoresistive effect element having a spin valve structure has a first thin film layer (free layer) and a second thin film layer (fixed layer) made of a ferromagnetic material separated by a nonmagnetic thin film layer. The magnetization direction of the first thin film layer of ferromagnetic material is set to be orthogonal to the fixed magnetization direction of the second thin film layer when the applied magnetic field is zero. In order to fix the magnetization direction of the ferromagnetic second thin film layer, the antiferromagnetic thin film layer is attached in direct contact with the second thin film layer. As an alternative structure, the antiferromagnetic thin film layer may be a ferromagnetic layer having a high coercivity.

The TMR element uses a nonmagnetic layer such as AlOx or MgO for the nonmagnetic layer that partitions the free layer and the fixed layer to detect a change in current flowing in a direction perpendicular to the film surface. The GMR element uses a conductive material such as Cu or Ru for the nonmagnetic layer to detect a change in current flowing in a direction parallel to the film surface. A CPP (Current-Perpendicular-to-Plane) -GMR element uses a conductive material such as Cu or Ru as a nonmagnetic layer to detect a change in current flowing in a direction perpendicular to the film surface.

By making the magnetization direction of the free layer and the fixed layer substantially perpendicular to each other when no external magnetic field is applied, a TMR element and a GMR element that can obtain a linear output with respect to the external magnetic field can be configured. By incorporating a magnetoelectric conversion element such as a TMR element into an IC (Integrated Circuit), the current flowing through the IC can be detected. For example, Patent Document 2 discloses a current sensor that detects a current flowing in an IC using a TMR element manufactured on the IC.

  By accurately detecting the current flowing through the IC, it is possible to detect an abnormal operation or failure of the element. In addition to detecting the inflow of an abnormal current signal, the power consumption of the IC is reduced by controlling the power consumption in the circuit to be suppressed.

Japanese Examined Patent Publication No. 8-21166 Special table 2007-520057

  The magnetic field generated by the current becomes weaker in inverse proportion to the distance from the electric wire. For this reason, in order to detect a weak current using the same magnetoelectric conversion element, it is preferable to bring the magnetoelectric conversion element close to the electric wire, but the rate of change of the magnetic field strength with respect to the change in the distance from the electric wire also increases. Therefore, the detection sensitivity becomes sensitive to variations between the electric wire and the magnetoelectric conversion element. If the magnetoelectric conversion element is arranged near the electric wire, the temperature of the magnetoelectric conversion element is likely to change due to the effect of Joule heat generated in the electric wire. For this reason, it was difficult to accurately detect a weak current.

The present invention has been made to solve such a problem, and an object thereof is to provide a current detector with high detection accuracy with a simple configuration.

A semiconductor device according to the present invention is connected to a substrate on which a semiconductor circuit is formed, a first wiring member disposed on the substrate, a vertical wiring member erected on the first wiring member, and a vertical wiring member The second wiring member laid in parallel with the first wiring member, the first magnetoelectric conversion element arranged to face the vertical wiring member, and the first magnetoelectric conversion element across the vertical wiring member The first magnetoelectric conversion element, the first element wiring connecting the first magnetoelectric conversion element and the second magnetoelectric conversion element in series, and the first amplification to which the midpoint of the first element wiring is input And a circuit.

According to the present invention, it is possible to reduce a current detection error caused by an overlay error that occurs between the magnetoelectric conversion element and the detection current line.

1 is a perspective view showing an overall configuration of a semiconductor device according to the present invention. FIG. 5 is a plan view showing a current detector according to the first embodiment, and shows a relationship between a fixed layer of a magnetoelectric conversion element and a detection current. The top view (a) and the side view (b) showing the current detector according to the first embodiment show the relationship between the magnetoelectric conversion element and the magnetic guide. It is a perspective view which shows the structure of the current detector in connection with Embodiment 2 of this invention. It is a top view showing the current detector in connection with Embodiment 2, and represents the relationship between the fixed layer of the magnetoelectric conversion element and the detected current. 6 is a perspective view showing a wiring structure of a magnetoelectric conversion element in a current detector according to Embodiment 2. FIG. It is a perspective view which shows the structure of the current detector in connection with Embodiment 3 of this invention. FIG. 9 is a plan view showing a current detector according to Embodiment 3, showing a relationship between a fixed layer of a magnetoelectric conversion element and a detection current. It is a perspective view which shows the structure of the current detector in connection with Embodiment 4 of this invention.

  In general, when a signal is detected from a change in resistance of an element, when current noise is applied to a power supply line connected to the element, the voltage at both ends of the element changes even if the signal to be detected does not change. It is known that a so-called half-bridge structure is preferable in order to prevent erroneous signal detection. In the half-bridge structure, two substantially equal elements are connected in series to pass an equal current, and the midpoint potential is detected.

  Consider that this structure is applied to the case of detecting the current flowing in the IC wiring. In order to provide two substantially equal elements in an IC, it is necessary not only to make the characteristics of the elements equal, but also to equalize the influence of the magnetic field generated from the current to be detected. For example, in the case of an MR element or a Hall element, this can be realized by making the shape and arrangement of the element appropriate. In the spin valve type GMR element and TMR element, it is necessary to further orient the magnetization direction of the fixed layer appropriately.

  The magnetic field formed by the current flowing inside the electric wire is formed so as to draw a circle around the central axis of the substantial current flow. The resistance change of the TMR element is greatest when the magnetic field is arranged so as to be applied in a direction perpendicular to the fixed layer. For this reason, when the plane perpendicular to the direction of current flow and the TMR element formation surface are not parallel, the plane perpendicular to the direction of current flow and the line parallel to the line formed by intersecting the TMR element formation plane are The TMR element is provided at two points on the straight line intersecting the central axis of the substantial current flow, and the distance from the current line is equal, and the surface perpendicular to the current flow direction and the TMR element formation surface are It is preferable to fix the magnetization direction of the fixed layer of the TMR element in a direction parallel to or anti-parallel to the intersecting line.

The magnetization direction of the fixed layer of the TMR element is fixed by performing a heat treatment while applying a magnetic field to the element. The TMR elements in the same chip are preferably arranged so that the magnetization directions of the fixed layers are the same and a half-bridge output can be obtained. However, in order to obtain different outputs from the two TMR elements arranged as described above, for example, an electric wire is bent to form at least two portions having different current flow directions, and close to the respective portions. Thus, it is necessary to form a TMR element.

At this time, the influence of the portions having different current flow directions on the distant TMR element is reduced. Since the TMR elements must be arranged with a sufficient interval, a large area is required on the IC in order to form a current detection line. This is not preferable because not only the restrictions on the miniaturization of the IC are increased, but also the in-plane distribution of the TMR element characteristics is easily affected.

On the other hand, when the plane perpendicular to the current flow direction and the TMR element formation surface are parallel, the TMR is set to two points that are on an arbitrary straight line intersecting the central axis of the substantial current flow and have the same distance from the electric wire. It is preferable to provide an element and fix the magnetization direction of the fixed layer of the TMR element in a parallel or antiparallel direction to a straight line connecting the two TMR elements.

If formed in this way, the TMR element is arranged at an equal distance with respect to a part of the electric wire perpendicular to the element forming surface, so that a current sensor can be provided in a small part such as both ends of the contact. For this reason, not only does it contribute to miniaturization of the IC, but it is also less susceptible to the in-plane distribution of TMR element characteristics. The shape of the TMR element viewed from the direction perpendicular to the element formation surface of the fixed layer is such that the magnetic domain structure of the free layer smoothly changes following the change of the magnetic field, such as a circle or an ellipse. Shape is preferred. Hereinafter, embodiments of the semiconductor device according to the present invention will be specifically described.

Embodiment 1 FIG.
First, a semiconductor device according to the present invention will be described with reference to FIG. FIG. 1 is a perspective view schematically showing a relationship between a semiconductor device and a current detector. On the left side, the semiconductor device 1 in which the circuit 1a is formed on the substrate 3 is displayed. The figure on the right side is an enlarged view of a part of the semiconductor device 1 and shows the configuration of the current detector 2 according to the first embodiment. The current detector 2 detects a current flowing through a circuit formed on the substrate 3. The current detector 2 includes magnetoelectric conversion elements 10 and 11, a detection current line 15, a voltage source 21, a differential amplifier circuit 22, and an element wiring 23.

The detection current line 15 includes a first portion (vertical wiring member) 16 provided substantially perpendicular to the substrate 3 and parallel portions 19 and 20 substantially parallel to the substrate 3. One end of the parallel portion (first wiring member) 19 is connected to the first portion 16 and is laid in parallel with the parallel portion (second wiring member) 20. The magnetoelectric conversion element 10 and the magnetoelectric conversion element 11 are connected in series by an element wiring 23 to form a half bridge. The voltage source 21 is connected to one end of the element wiring 23, and the other end is dropped to the ground. A midpoint 23 a of the magnetoelectric conversion element 10 and the magnetoelectric conversion element 11 is input to the differential amplifier circuit 22.

FIG. 2 shows the relationship between the fixed layer of the magnetoelectric transducer and the detected current. The detected current (current to be measured) flows through the parallel portion 20, the first portion 16, and the parallel portion 19. The magnetoelectric conversion elements 10 and 11 are arranged at approximately the same distance from the center of the first portion 16 and at positions opposite to each other. The magnetization direction of the fixed layer of the magnetoelectric conversion elements 10 and 11 may be either, but the magnetoelectric conversion element 10 is an in-plane direction in which the fixed layer is formed so that the influence of the parallel portions 19 and 20 is offset. The first portion 16 is preferably perpendicular to the desired direction. That is, the magnetization direction faces the longitudinal direction of the parallel portions 19 and 20. The magnetization directions of the fixed layers of the magnetoelectric conversion elements 10 and 11 are substantially equal.

The magnetic field generated around the first portion 16 is proportional to the current flowing through the detection current line 15. By connecting the voltage source 21 to the half bridge and amplifying the potential difference between the midpoint potential and the reference voltage, an output corresponding to the current flowing through the detection current line 15 can be obtained. The reference voltage may be connected to an appropriate constant voltage source.For example, a resistance element formed substantially the same is connected in series and connected to the same voltage source as that of the half bridge, and the midpoint potential thereof is set. It may be a reference voltage. According to the current detector 2 of the first embodiment, it is possible to form a current detector that can detect the current flowing through the wiring without forming a large current path in the IC. In addition, since the half bridge is composed of magnetoelectric transducers with uniform temperature characteristics, it is less susceptible to resistance changes due to temperature.

FIG. 3 is a top view (a) and a side view (b) showing the current detector. The parallel portion 19 is disposed on the insulating film 27 formed on the substrate 3. The magnetoelectric conversion elements 10 and 11 are preferably formed between the parallel part 19 and the parallel part 20. The magnetoelectric transducers 10 and 11 may be provided with a magnetic flux guide. In this figure, a magnetic flux guide (yoke) 24 made of a magnetic material is provided so as to surround the magnetoelectric conversion elements 10 and 11. The magnetic material can pass more magnetic flux than the non-magnetic material, and the magnetic guide 24 can collect (collect) the magnetic flux.

Embodiment 2. FIG.
FIG. 4 is a perspective view schematically showing a configuration of a current detector according to Embodiment 2 of the present invention. The current detector 2 includes magnetoelectric conversion elements 10, 11, 12, 13, a detection current line 15, a voltage source 21, and a differential amplifier circuit 22. The detection current line 15 through which the current to be detected flows is a first portion (first vertical wiring member) 16 and a second portion (second vertical wiring member) provided substantially perpendicular to the substrate 3. 17 is provided. The detection current line 15 includes parallel portions 18, 19, and 20 that are substantially parallel to the substrate. One end of the parallel portion 20 is connected to the first portion 16 and is laid in parallel to the parallel portion 19. One end of the parallel part (third wiring member) 18 is connected to the second part 17 and is laid in parallel with the parallel part 19.

The detected current (current to be measured) flows through the parallel part 20, the first part 16, the parallel part 19, the second part 17, and the parallel part 18. The magnetoelectric conversion elements 10 and 11 are arranged at approximately the same distance from the center of the first portion 16 and at positions opposite to each other. The magnetoelectric transducers 12 and 13 are arranged at approximately the same distance from the center of the second portion 17 at the opposite positions. The magnetoelectric conversion element 10 and the magnetoelectric conversion element 13 are connected in series by an element wiring 23A to form a half bridge. The magnetoelectric conversion element 11 and the magnetoelectric conversion element 12 are connected in series by an element wiring 23B to form a half bridge. The voltage source 21 is connected to one end of the element wirings 23A and 23B, and the other end is dropped to the ground. The midpoint 23 a of the magnetoelectric conversion element 10 and the magnetoelectric conversion element 13 and the midpoint 23 b of the magnetoelectric conversion element 11 and the magnetoelectric conversion element 12 are input to the differential amplifier circuit 22.

FIG. 5 is a plan view schematically showing the configuration of the current detector 2 according to the second embodiment. The magnetization direction of the fixed layer of the magnetoelectric conversion elements 10 and 11 is an in-plane direction in which the fixed layer is formed and is perpendicular to the direction in which the first portion 16 is desired from the magnetoelectric conversion element 10. The magnetization direction of the pinned layer of the magnetoelectric conversion elements 12 and 13 is an in-plane direction in which the pinned layer is formed and is perpendicular to the direction in which the second portion 17 is desired from the magnetoelectric conversion element 12. It is preferable that the magnetization directions of the fixed layers of the magnetoelectric conversion elements 10 to 13 are all equal. More preferably, the magnetization direction of the fixed layer is parallel to the longitudinal direction of the parallel portions 18 to 20.

The magnetic field generated by the current flowing through the first portion 16 and the second portion 17 is generated in the direction described by the thin arrows in FIG. When current flows through the detection current line 15, the resistances of the magnetoelectric conversion elements 10 and 12 increase with reference to the resistance when no current flows because the magnetization directions of the fixed layer and the free layer approach antiparallel. . However, when a current flows through the detection current line 15, the resistances of the magnetoelectric conversion elements 11 and 13 decrease with reference to the resistance when no current flows because the magnetization directions of the fixed layer and the free layer approach parallel. .

When a magnetoelectric conversion element having a characteristic in which resistance changes linearly with respect to a magnetic field is used, an output proportional to the amount of current to be measured is generated from the differential amplifier circuit 22. The magnetoelectric conversion elements 10 to 13 are preferably elements such as TMR elements or CPPGMR elements that allow current to flow perpendicularly to the substrate. The magnetic field changes depending on the distance from the wiring through which the current to be measured flows. It is desirable that the size of the magnetoelectric transducers 10 and 11 is smaller than the area where the first portion 16 and the surface on which the magnetoelectric transducer is formed intersect so that it is not easily affected by the size of the device. . Similarly, the size of the magnetoelectric conversion elements 12 and 13 is desirably smaller than the area where the second portion 17 and the surface on which the magnetoelectric conversion elements are formed intersects.

The wiring of the magnetoelectric conversion element is preferably configured as shown in FIG. 6, for example. In this example, the element wiring (wirings A to F) 23 for connecting the magnetoelectric conversion elements and the detection current line 15 through which the current to be measured flows are simultaneously formed at the same height from the substrate surface. A differential amplifier circuit 22 is connected to the wirings A and B. A constant pressure source 21 is connected to the wirings C and E. The wirings D and F are grounded. By doing so, an output proportional to the amount of current to be measured can be obtained.

  According to the current detector 2 of the second embodiment, the mask for patterning the magnetoelectric transducers 10 to 13 and the mask for patterning (contact holes) of the first portion 16 and the second portion 17 are not translated. Even if the error occurs, the influences cancel each other, so that the influence on the output can be reduced and the current detection accuracy can be improved.

Embodiment 3 FIG.
A third embodiment will be described with reference to FIGS. As shown in FIG. 7, the current detector 2 according to the present invention includes four magnetoelectric conversion elements 10 to 13 around the first portion 16 provided substantially perpendicular to the substrate, and the magnetization direction of the fixed layer. And a straight line extending in the vertical direction and passing through the center of the first portion 16. The magnetoelectric conversion elements 10 and 11 are arranged on the opposite side with the first portion 16 in between. The element wiring 23A connects the magnetoelectric conversion elements 10 and 11 in series and constitutes a first half bridge.

The magnetoelectric conversion element 12 is disposed outside the magnetoelectric conversion element 11. The magnetoelectric conversion element 13 is disposed outside the magnetoelectric conversion element 10. The element wiring 23B connects the magnetoelectric conversion elements 12 and 13 in series, and constitutes a second half bridge. The first half bridge and the second half bridge have different distances from the first portion 16. The midpoint 23a of the first half bridge is connected to the operational amplifier circuit 22a. The midpoint 23b of the second half bridge is connected to the operational amplifier circuit 22b.

  It is known that the strength (H) of the magnetic field at a position r away from the electric wire through which the current I flows is H = I / 2πr according to Ampere's law. If the distance from the detection current line 15 (the first portion 16) is r, the first half bridge can express the magnetic field H1 detected by the first half bridge as H1 = I / 2πr. Similarly, when the distance from the detection current line 15 (first portion 16) is r + δr, the magnetic field H2 detected by the second half bridge is H2 = I / 2π (r + δr). By combining these equations, r is obtained in the form of r = H2 / (H1−H2) * δr.

Since the current in the IC fluctuates at a high speed, the current distribution in the wiring due to the skin effect cannot be ignored when the current is detected at high speed using the TMR element. When a high frequency current is detected, the current is distributed near the surface of the wiring due to the skin effect, so the distance between the current line and the TMR element is effectively shortened, and the amount of current is estimated more than the actual amount. In the present embodiment, the effective distance between the wiring and the TMR element is obtained from the outputs of two half bridges having different distances from the electric wire. By correcting with this value, the amount of current can be detected correctly.

  When a magnetic field higher than the saturation magnetic field is applied to the TMR element, the resistance becomes constant and the magnetic field cannot be detected. In Embodiment 3, the half bridge by the two TMR elements provided in the position where the distance from an electric wire differs is provided. When the amount of current is small, the current is detected with high accuracy by referring to the output of the first half bridge close to the first portion 16. When the amount of current is large and the output of the first half bridge is saturated, a high current can be detected with reference to the output of the second half bridge far from the first portion 16. As a result, a current detector with high accuracy and a wide detection current range can be obtained.

The outputs of the first half bridge and the second half bridge may be analog-calculated as they are, or may be digitally converted by an AD converter to perform a desired calculation depending on the application. Further, in the present embodiment, an example of two half bridges has been shown, but by using three or more half bridges and using signals from TMR elements arranged at a distance suitable for the measurement magnetic field range, Current can be detected with high accuracy corresponding to a wider current range.

Embodiment 4 FIG.
The fourth embodiment will be described with reference to FIG. The current detector shown in FIG. 9 includes a first half bridge and a second half bridge, similarly to the current detector shown in FIG. The midpoint 23a of the first half bridge is connected to the operational amplifier circuit 22a. The midpoint 23b of the second half bridge is connected to the operational amplifier circuit 22b. The current detector 2 shown in the fourth embodiment includes an output selection circuit 25. The output selection circuit 25 outputs the output of the differential amplifier circuit 22a or the differential amplifier circuit 22b to Vout according to an instruction from the control circuit 26.

  DESCRIPTION OF SYMBOLS 1 Semiconductor device, 2 Current detector, 3 Substrate, 10-13 Magnetoelectric conversion element, 15 Detection current line, 16 1st part, 17 2nd part, 18-20 Parallel part, 21 Voltage source, 22 Differential amplification Circuit, 23 element wiring, 24 magnetic flux guide, 25 output selection circuit, 26 control circuit, 27 insulating film

Claims (8)

A substrate on which a semiconductor circuit is formed;
A first wiring member disposed on the substrate;
A vertical wiring member erected on the first wiring member;
A second wiring member connected to the vertical wiring member and laid in parallel with the first wiring member;
A first magnetoelectric transducer disposed opposite to the vertical wiring member;
A second magnetoelectric conversion element facing the first magnetoelectric conversion element across the vertical wiring member;
A first element wiring connecting the first magnetoelectric conversion element and the second magnetoelectric conversion element in series;
And a first amplifier circuit to which a midpoint of the first element wiring is input. A third magnetoelectric conversion element disposed outside the first magnetoelectric conversion element;
A fourth magnetoelectric conversion element disposed opposite to the third magnetoelectric conversion element across the vertical wiring member and disposed outside the vertical wiring member with respect to the second magnetoelectric conversion element;
A second element wiring connecting the third magnetoelectric conversion element and the fourth magnetoelectric conversion element in series;
The semiconductor device according to claim 1, further comprising: a second amplifier circuit to which a midpoint of the second element wiring is input. The magnetization direction of the fixed layer of the first magnetoelectric conversion element and the magnetization direction of the fixed layer of the second magnetoelectric conversion element are oriented in the same direction and in the longitudinal direction of the first wiring member. The semiconductor device according to claim 1. The magnetization direction of the fixed layer of the third magnetoelectric conversion element and the magnetization direction of the fixed layer of the fourth magnetoelectric conversion element are oriented in the same direction and in the longitudinal direction of the first wiring member. The semiconductor device according to claim 2. The semiconductor device according to claim 2, wherein a magnetic flux guide is provided in each of the first to fourth magnetoelectric conversion elements. 3. The semiconductor device according to claim 2, further comprising a selection switch that selects an output selected from the output of the first amplifier circuit and the output of the second amplifier circuit. A substrate on which a semiconductor circuit is formed;
A first wiring member disposed on the substrate;
A first vertical wiring member erected on the first wiring member;
A second wiring member connected to the first vertical wiring member and laid in parallel with the first wiring portion;
A second vertical wiring member erected on the first wiring member spaced from the first vertical wiring member;
A third wiring member connected to the second vertical wiring member and laid in parallel with the first wiring member;
A first magnetoelectric transducer disposed opposite to the first vertical wiring member;
A second magnetoelectric conversion element facing the first magnetoelectric conversion element across the first vertical wiring member;
A third magnetoelectric transducer disposed opposite to the second vertical wiring member;
A fourth magnetoelectric conversion element facing the third magnetoelectric conversion element across the second vertical wiring member;
A first element wiring connecting the first magnetoelectric conversion element and the second magnetoelectric conversion element in series;
A second element wiring connecting the third magnetoelectric conversion element and the fourth magnetoelectric conversion element in series;
A semiconductor device comprising: an amplifier circuit to which a midpoint of the first element wiring and a midpoint of the second element wiring are input. The magnetization direction of the fixed layer of the 1st magnetoelectric conversion element to the 4th magnetoelectric conversion element has faced the same direction, and has faced the longitudinal direction of the 1st wiring member. The semiconductor device described.

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