WO2013123873A1 - 用于测量磁场的磁电阻传感器 - Google Patents

用于测量磁场的磁电阻传感器 Download PDF

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WO2013123873A1
WO2013123873A1 PCT/CN2013/071676 CN2013071676W WO2013123873A1 WO 2013123873 A1 WO2013123873 A1 WO 2013123873A1 CN 2013071676 W CN2013071676 W CN 2013071676W WO 2013123873 A1 WO2013123873 A1 WO 2013123873A1
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sensor
magnetoresistive
arm
magnetic field
bridge
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PCT/CN2013/071676
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English (en)
French (fr)
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迪克詹姆斯·G
金英西
沈卫锋
薛松生
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江苏多维科技有限公司
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Priority to US14/379,706 priority Critical patent/US11287490B2/en
Priority to JP2014557985A priority patent/JP6420665B2/ja
Priority to EP13751243.0A priority patent/EP2818884B1/en
Publication of WO2013123873A1 publication Critical patent/WO2013123873A1/zh

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
    • G01R33/06—Measuring direction or magnitude of magnetic fields or magnetic flux using galvano-magnetic devices
    • G01R33/09—Magnetoresistive devices
    • G01R33/093—Magnetoresistive devices using multilayer structures, e.g. giant magnetoresistance sensors
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
    • G01R33/06—Measuring direction or magnitude of magnetic fields or magnetic flux using galvano-magnetic devices
    • G01R33/09—Magnetoresistive devices
    • G01R33/098—Magnetoresistive devices comprising tunnel junctions, e.g. tunnel magnetoresistance sensors
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N50/00—Galvanomagnetic devices
    • H10N50/10—Magnetoresistive devices
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
    • G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
    • G01R15/20—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using galvano-magnetic devices, e.g. Hall-effect devices, i.e. measuring a magnetic field via the interaction between a current and a magnetic field, e.g. magneto resistive or Hall effect devices
    • G01R15/205—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using galvano-magnetic devices, e.g. Hall-effect devices, i.e. measuring a magnetic field via the interaction between a current and a magnetic field, e.g. magneto resistive or Hall effect devices using magneto-resistance devices, e.g. field plates

Definitions

  • the present invention relates to a magnetoresistive sensor, and more particularly to a magnetoresistive sensor for measuring a magnetic field.
  • Magnetic sensors are widely used in modern systems to measure or induce physical parameters such as magnetic field strength, current, position, motion, and direction.
  • sensors for measuring magnetic fields and other parameters.
  • they are subject to various well-known limitations in the prior art, such as oversize, low sensitivity, narrow dynamic range, high cost, low reliability, and other factors. Therefore, it is necessary to continuously improve the magnetic sensor, particularly to improve the sensor and its manufacturing method which are easily integrated with the semiconductor device or integrated circuit.
  • the tunnel junction magnetoresistive sensor has the advantages of high sensitivity, small size, low cost and low power consumption. Despite MTJ The sensor is compatible with semiconductor standard manufacturing processes, but the high sensitivity MTJ sensor does not achieve low cost mass production. In particular, the yield of the sensor depends on the MTJ. The offset value of the reluctance output of the component makes it difficult to achieve a high degree of matching of the magnetic resistance of the MTJ constituting the bridge, and the manufacturing process of the orthogonal magnetic field sensor integrated on the same semiconductor substrate is very complicated.
  • the response of the magnetoresistive element that can be used for the sensor is a function of the magnetization direction of the multilayer film made up of the sensing material.
  • an external field is usually required to bias the magnetic moment to operate at a stable and sensitive operating point.
  • This type of biasing typically uses external coils or permanent magnets.
  • the present invention provides a magnetoresistive sensor for measuring a magnetic field, which can realize mass production, has higher sensitivity for measuring a magnetic field, and has the characteristics of low power consumption and small size.
  • the invention discloses a magnetoresistive sensor for measuring a magnetic field, which comprises:
  • the sensitive axis of the magnetoresistive sensor being parallel to the Y axis, and the X axis being perpendicular to Y Axis
  • At least one sensing arm is composed of a magnetoresistive element disposed on the 'X-Y' surface of the substrate, and the magnetoresistive element is along Y The length in the axial direction is greater than its length along the X-axis;
  • a plurality of strip-shaped permanent magnets disposed on the substrate of the magnetoresistive sensor, and a gap magnetic field is formed between two adjacent strip-shaped permanent magnets, the gap magnetic field having an edge along X
  • a pad disposed at the end of the sensing arm, through which the sensing arm can be electrically connected.
  • At least one of the magnetoresistive elements is saturated by the gap magnetic field in the X-axis direction.
  • the response curve of the magnetoresistance resistance of the magnetoresistive sensor as a function of the external field has high linearity, high slope value, and low hysteresis in the working range of the magnetoresistive sensor.
  • the strip permanent magnet is magnetized to adjust the magnetization and direction of the strip permanent magnet to adjust the output performance of the magnetoresistive sensor.
  • the magnetoresistive element is an MTJ element or a GMR element.
  • the magnetoresistive sensor is a bridge magnetic field sensor.
  • the bridge magnetic field sensor is a push-pull full-bridge magnetic field sensor.
  • the push-pull full-bridge magnetic field sensor comprises four sensing arms, and the magnetic resistance of the resistance of the two sensing arms with the external field in the working interval of the magnetoresistive sensor is opposite to the magnetic resistance of the other two sensing arms.
  • the response curve of the resistance change with the external field has an opposite trend under the same external field.
  • the push-pull full-bridge magnetic field sensor comprises two sensor chips, each sensor chip comprising 'X-Y 'The surface of the substrate and the two sensor arms disposed on the surface of the substrate, one of which is arranged 180 degrees apart from the other sensor chip, and the two sensor chips are cut from the same wafer.
  • the electrical connection can be made between the sensing arms via the lead connection pads.
  • the bridge magnetic field sensor is a reference full bridge magnetic field sensor comprising a sensing arm and a reference arm, each reference arm being comprised of a magnetoresistive element.
  • the reference full-bridge magnetic field sensor comprises two sensing arms and two reference arms.
  • the absolute value of the slope of the response curve of the magnetoresistance of the sensing arm with the external field is much larger than the reference.
  • the reference full bridge magnetic field sensor comprises a sensor chip including 'X-Y The substrate of the surface and the magnetoresistive element constituting the sensor arm and the magnetoresistive element constituting the reference arm provided on the surface of the substrate.
  • the length of the magnetoresistive element constituting the reference arm in the X-axis direction is greater than its length along the Y-axis direction, and its along the X The length in the axial direction is greater than the length of the magnetoresistive element constituting the sensing arm in the X-axis direction.
  • the surface of the magnetoresistive element constituting the reference arm is covered with a ferromagnetic shielding layer of high magnetic permeability.
  • the magnetic field component of the strip-shaped permanent magnet disposed near the reference arm in the X-axis direction is larger than the strip-shaped permanent magnet disposed near the sensing arm at the X The magnetic field component in the axial direction.
  • the magnetoresistive element constituting the reference arm or the sensing arm is provided with a permanent magnet bias layer composed of a film or a multilayer film.
  • the magnetoresistive element constituting the reference arm is provided with an exchange bias layer composed of a film or a multilayer film.
  • the bridge magnetic field sensor is a push-pull half-bridge magnetic field sensor, and the push-pull half-bridge magnetic field sensor is composed of two sensing arms.
  • the push-pull half-bridge magnetic field sensor comprises two sensing arms, and the resistance curve of the resistance value of one of the sensing arms with the external field in the working interval of the magnetoresistive sensor is opposite to the resistance of the other sensor arm.
  • the response curve with the external field changes has the opposite trend under the same external field.
  • the push-pull half-bridge magnetic field sensor comprises two sensor chips, each sensor chip comprising 'X-Y A surface substrate and a sensor arm disposed on the surface of the substrate, wherein one sensor chip is arranged 180 degrees apart from the other sensor chip, and the two sensor chips are cut from the same wafer.
  • the electrical connection between the sensing arms of the push-pull half-bridge magnetic field sensor can be achieved by wire bond pads.
  • the magnetoresistive sensor is a reference half bridge magnetic field sensor comprising a sensing arm and a reference arm, each reference arm being constituted by a magnetoresistive element.
  • the reference half-bridge magnetic field sensor comprises an inductive arm and a reference arm, and the absolute value of the slope of the response curve of the magnetoresistance resistance of the sensing arm with the external field in the working range of the magnetoresistive sensor is much larger than the magnetic value of the reference arm.
  • the absolute value of the slope of the response curve of the resistance value as a function of the external field.
  • the reference half bridge magnetic field sensor comprises a sensor chip comprising 'X-Y The substrate of the surface and the magnetoresistive element constituting the sensor arm and the magnetoresistive element constituting the reference arm provided on the surface of the substrate.
  • the length of the magnetoresistive element constituting the reference arm in the X-axis direction is greater than its length along the Y-axis direction, and its along the X The length in the axial direction is greater than the length of the magnetoresistive element constituting the sensing arm in the X-axis direction.
  • the surface of the magnetoresistive element constituting the reference arm is covered with a ferromagnetic shielding layer of high magnetic permeability.
  • the magnetic field component of the strip-shaped permanent magnet disposed near the reference arm in the X-axis direction is larger than the strip-shaped permanent magnet disposed near the sensing arm The magnetic field component in the X-axis direction.
  • the magnetoresistive element constituting the reference arm or the sensing arm is provided with a permanent magnet bias layer composed of a film or a multilayer film.
  • the magnetoresistive element constituting the reference arm is provided with an exchange bias layer composed of a film or a multilayer film.
  • the magnetoresistive sensor is a semi-push-pull full-bridge magnetic field sensor consisting of two independent current drive sources and two sensor arms fully bridged.
  • the response curve of the magnetoresistance resistance of one of the semi-push-pull full-bridge magnetic field sensors varies with the external field, and the response curve of the magnetoresistance of the other sensor arm with the external field changes in the same external field. The trend of change.
  • the semi-push-pull full bridge magnetic field sensor comprises two sensor chips, each sensor chip comprising 'X-Y A surface substrate and a sensor arm disposed on the surface of the substrate, wherein one sensor chip is arranged 180 degrees apart from the other sensor chip, and the two sensor chips are cut from the same wafer.
  • the electrical connection between the sensing arms of the semi-push-pull full-bridge magnetic field sensor can be achieved by wire bond pads.
  • the magnetoresistive sensor is a semi-reference full bridge magnetic field sensor composed of two independent current driving sources, one sensing arm and one reference arm full bridge connection.
  • the absolute value of the slope of the response curve of the magnetoresistance resistance of the sensor arm as a function of the external field is much larger than the absolute value of the slope of the response curve of the magnetoresistance resistance of the reference arm as a function of the external field.
  • the semi-reference full bridge magnetic field sensor comprises a sensor chip comprising 'X-Y The substrate of the surface and the magnetoresistive element constituting the sensor arm and the magnetoresistive element constituting the reference arm provided on the surface of the substrate.
  • the length of the magnetoresistive element constituting the reference arm in the X-axis direction is greater than its length along the Y-axis direction, and its along the X The length in the axial direction is greater than the length of the magnetoresistive element constituting the sensing arm in the X-axis direction.
  • the surface of the magnetoresistive element constituting the reference arm is covered with a ferromagnetic shielding layer of high magnetic permeability.
  • the magnetic field component of the strip-shaped permanent magnet disposed near the reference arm in the X-axis direction is larger than the strip-shaped permanent magnet disposed near the sensing arm The magnetic field component in the X-axis direction.
  • the magnetoresistive element constituting the reference arm or the sensing arm is provided with a permanent magnet bias layer composed of a film or a multilayer film.
  • the magnetoresistive element constituting the reference arm is provided with an exchange bias layer composed of a film or a multilayer film.
  • the present invention provides a standard semiconductor manufacturing process, a linear bridge magnetoresistive sensor for mass production.
  • the sensor uses a highly sensitive magnetoresistive sensing element such as a tunnel junction magnetoresistance (MTJ) or a giant magnetoresistance ( GMR Multilayer film.
  • MTJ tunnel junction magnetoresistance
  • GMR Multilayer film a giant magnetoresistance
  • a monolithic permanent magnet is used to create a field of dispersion to provide a bias field that counteracts the non-ideal magnetic behavior of the sensing element.
  • the bias field generated by the permanent magnet balances the internal shape along the sensitive direction and the anisotropy energy of the material, while the cross-axis magnetic bias field optimizes the sensitivity of the sensor. Therefore, the high-sensitivity magnetic field sensing element can further enhance its low offset, high linearity, and good temperature stability by connecting into a bridge form to broaden its applicable field.
  • Figure 1 is a cross-sectional view of a tunnel junction magnetoresistance (MTJ) at MTJ An ohmmeter is connected between the top electrode layer and the bottom electrode layer of the element to show the change in resistance.
  • MTJ tunnel junction magnetoresistance
  • Figure 2 is a schematic diagram of the magnetoresistance response of the spin valve element reference layer magnetized along the hard axis direction.
  • Figure 3 is a response graph of the MTJ component.
  • Figure 4 shows the MTJ component rotated 180 ° under the same external field (flipped die ) response curve.
  • Figure 5 is a schematic diagram of connecting a plurality of MTJ elements into one magnetoresistive element.
  • Figure 6 is a circuit diagram of the push-pull full-bridge sensor.
  • Figure 7 is a circuit diagram of a reference full bridge sensor.
  • Figure 8 is a circuit diagram of the push-pull half-bridge sensor.
  • Figure 9 is a circuit diagram of a reference half-bridge sensor.
  • Figure 10 is a circuit diagram of a semi-push-pull full-bridge magnetic field sensor.
  • Figure 11 is a circuit diagram of a half-reference full-bridge sensor.
  • Figure 12 is a schematic diagram of the output voltage simulation of the bridge circuit as a function of the external field.
  • the bridge circuit consists of four high-sensitivity MTJs.
  • the bridge arms of the components are arranged in an inverted arrangement.
  • Figure 13 shows the location of the integrated permanent magnets.
  • the permanent magnets are parallel to the long axis and the sensitive axis of the MTJ sensing element.
  • Figure 14 is a cross-sectional view of the permanent magnet and MTJ element shown in Figure 13 and the magnetic line distribution of a pair of permanent magnets.
  • Figure 15 shows the offset and saturation fields of the response curve by setting the field strength and direction around the MTJ component.
  • Figure 16 shows the magnetic field distribution between a pair of chip permanent magnets in which the sensing element is located.
  • the magnetic field strength is a function of the width of the magnet and the spacing of the magnets.
  • Figure 17 is a schematic view showing the magnetic field component around the magnetoresistive element of Figure 16.
  • Figure 18 is a graph of sensitivity versus H cross /H k .
  • Figure 19 It is a sensor design layout diagram in which two chips are flipped. Each chip has two sensing arms, and the two chips form a full bridge. The same two chips are rotated 180 ° along the standard axis of the substrate.
  • Figure 20 Is a canonical reference bridge sensor chip layout that uses a tilted permanent magnet to set the bias field of the sensing arm, and a vertically aligned permanent magnet sets the bias field of the reference arm to optimize the output of the bridge while The shield layer can be selectively set.
  • FIG. 1 is a schematic diagram of the structure and electronic measurement of a Magnetic Tunnel Junctions (MTJ) component.
  • the MTJ element 1 is composed of a pinning layer 2, a tunnel barrier layer 5, and a ferromagnetic layer (sensitive layer) 6.
  • the pinning layer 2 is composed of a ferromagnetic layer (pinned layer) 4 and an antiferromagnetic layer 3, and the exchange coupling between the ferromagnetic layer 4 and the antiferromagnetic layer 3 determines the magnetization direction of the ferromagnetic layer 4;
  • the barrier layer 5 is usually formed of MgO or Al 2 O 3 and is located at the upper portion of the ferromagnetic layer 4.
  • the ferromagnetic layer 6 is located at the upper portion of the tunnel barrier layer 5.
  • Arrows 8 and 7 represent the magnetization directions of the pinned layer 4 and the sensitive layer 6, respectively.
  • the direction 8 of the magnetic moment of the pinned layer 4 is relatively fixed under the action of a magnetic field of a certain magnitude, and the direction of the magnetic moment 7 of the sensitive layer 6 is relatively free and rotatable relative to the direction 8 of the magnetic moment of the pinned layer 4.
  • the typical thickness of each layer indicated by 3, 4, 5, and 6 is between 0.1 nm and 100 nm.
  • the bottom electrode layer 16 and the top electrode layer 17 are directly associated with the antiferromagnetic layer 3 and the sensitive layer 6 Electrical contact.
  • the electrode layer is typically a non-magnetic conductive material that is capable of carrying current into the ohmmeter 18 .
  • Ohm meter 18 Applicable to known currents through the entire tunnel junction and measuring current (or voltage).
  • the tunnel barrier layer 5 provides most of the device's resistance, approximately 1000 ohms, while the resistance of all conductors is approximately 10 ohms.
  • the bottom electrode layer 16 is located above the insulating substrate 9, and the insulating substrate 9 is wider than the bottom electrode layer 16, which is located on the substrate 10 made of other materials. Above.
  • the material of the substrate is usually silicon, quartz, heat-resistant glass, GaAs, AlTiC. Or any other material that can be integrated on the wafer. Silicon is the best choice because it is easy to process into an integrated circuit (although magnetic sensors do not always need such a circuit).
  • the output of a GMR or MTJ component suitable for linear magnetic field measurements is shown in Figure 2.
  • the response curve 20 is saturated at low resistance state 21 and high resistance state 22, and R L and R H represent resistance values of low resistance state and high resistance state, respectively.
  • the region of the response curve 20 between the saturation fields varies linearly with the external field Hsense .
  • the external field Hsense is parallel to the sensitive axis of the sensing element.
  • the direction 8 of the magnetic moment of the pinned layer 4 is anti-parallel to the sensitive axis, meaning that it points in the direction of -H.
  • the response curve 20 of the magnetoresistive element is the maximum value, and when the two are parallel, it is the minimum value.
  • the intermediate value of the magnetoresistance response curve 20 varies with the angle between the free layer 6 and the pinned layer 4.
  • the H O value is often referred to as 'Orange Peel' or 'Neel Coupling', and its typical value is 1 to 40 Oe, the specific value of which is related to the structure and flatness of the ferromagnetic film in the magnetoresistive element. Depends on the material and manufacturing process.
  • H S is a saturated field.
  • H S is quantitatively defined as a value corresponding to the intersection of the tangent of the linear region and the tangent of the positive and negative saturation curves, which is taken in the case where the asymmetry of the response curve with respect to the H o point is eliminated.
  • Figure 2 shows the response curve 20 under ideal conditions.
  • the magnetoresistance R has a perfect linear relationship with the change of the external field H sense , and there is no hysteresis (in the actual case, the response curve of the magnetoresistance has a hysteresis with the change of the external field, which is called hysteresis.
  • the response curve of the magnetoresistance is a loop, which is usually used as a magnetoresistive material with a small hysteresis, which can be regarded as a perfect linear curve in practical use. In the field of practical sensors, this curve 20 will be more curved due to the constraints of the magnetic sensor design and the defects of the material.
  • the invention relates to the design and structure of the sensor and the process capable of being produced and implemented.
  • the sensor has excellent work induction and has high linearity, low hysteresis and high sensitivity in the working area (ie, the slope of the magnetoresistance response curve is large). ).
  • the RH sense curve 30 has a resistance value R L of a low resistance state 21 and a resistance value R H of a high resistance state 22.
  • the region of high sensitivity is near zero field, and the sensor's working range is near zero field, which is about 1/3 of the saturation field between 25 and 26.
  • the slope of the curve is proportional to the sensitivity of the sensor.
  • the zero field tangent 33 intersects the low field tangent 34 and the high field tangent 35 at point 25 (-H S + H O ) and point 26 ( H S + H O ), respectively. As shown in Fig.
  • the curve 30 corresponds to the high resistance state; when the magnetic moment direction 7 and the magnetic moment direction 8 are parallel, the curve 30 corresponds to the low resistance state.
  • the resistance is the intermediate value between R L and R H , which is the 'working point' of the ideal linear magnetic sensor.
  • another magnetoresistance R is a curve of the external field Hsense , which is rotated by 180° along the normal of the sensor. Under the action of the same external field H sense , the direction of the vector magnetic moment of the magnetoresistive R and the pinned layer 4 is parallel to the external field Hsense . In this case, the slope of the RH sense of the rotating chip is negative. Normally placed magnetoresistance and a 180° rotating magnetoresistance can construct a bridge, which proves to be larger than other possible methods.
  • magnetoresistive element strings are used as magnetoresistive arms of more complicated circuit structures.
  • the MTJ element 40 is on the bottom electrode layer 41 and the top electrode layer 42.
  • the internal current 43 flows vertically through the MTJ element 40 in the horizontal direction alternately through the top electrode layer and the bottom electrode layer.
  • the bottom electrode layer 41 is above the insulating layer 9, and the insulating layer 9 Located on the base substrate 10.
  • a pad that is, a resistive arm and other components such as an ohmmeter.
  • connection or the components on this circuit, can be connected to the components of other circuits on the chip through this pad without any other connection. Under normal conditions, the direction of current flow does not affect the effective resistance of the bridge arm resistance.
  • Keep the reference arm and the sensor arm The same size of the MTJ component is advantageous because it causes the etch bias of the device to be insensitive, and the resistance value of the MTJ component string of the reference arm and the sensing arm can be based on MTJ.
  • the number of components is set to change.
  • the bridge is used to change the signal of the magnetoresistive sensor so that its output voltage is easily amplified. This can change the noise of the signal, cancel the common mode signal, and reduce temperature drift or other deficiencies.
  • the component strings can be connected to form a Wheatstone bridge or other bridge.
  • Figure 6 It is a schematic diagram of a push-pull full-bridge sensor circuit.
  • the push-pull full-bridge magnetic field sensor includes four sensing arms. In the working range of the magnetoresistive sensor, the response curves of the resistance values of the two sensing arms with the external field change with respect to the magnetic resistance of the other two sensing arms with the external field. The varying response curves have opposite trends under the same external field action.
  • the push-pull full-bridge magnetic field sensor includes two sensor chips, each of which includes 'X-Y 'The surface of the substrate and the two sensing arms disposed on the surface of the substrate, one of which is arranged 180 degrees apart from the other sensor chip, and the two sensor chips are cut from the same wafer.
  • Figure 7 is a schematic diagram of a reference full bridge sensor circuit.
  • the bridge magnetic field sensor is a reference full bridge magnetic field sensor including a sensing arm and a reference arm, each reference arm being composed of a magnetoresistive element.
  • the reference full-bridge magnetic field sensor includes two sensing arms and two reference arms.
  • the absolute value of the slope of the response curve of the magnetoresistance of the sensing arm with the external field is much larger than the magnetic resistance of the reference arm.
  • the reference full bridge magnetic field sensor includes a sensor chip including the 'X-Y The substrate of the surface and the magnetoresistive element constituting the sensor arm and the magnetoresistive element constituting the reference arm provided on the surface of the substrate.
  • Figure 8 is a schematic diagram of the push-pull half-bridge sensor circuit.
  • the bridge magnetic field sensor is a push-pull half-bridge magnetic field sensor, and the push-pull half-bridge magnetic field sensor is composed of two sensing arms.
  • the push-pull half-bridge magnetic field sensor comprises two sensing arms.
  • the resistance curve of the resistance of one of the sensing arms with the external field changes with the resistance of the other sensor arm with the external field.
  • the response curve has an opposite trend under the same external field.
  • the push-pull half-bridge magnetic field sensor includes two sensor chips, each of which includes 'X-Y A surface substrate and a sensor arm disposed on the surface of the substrate, wherein one sensor chip is arranged 180 degrees apart from the other sensor chip, and the two sensor chips are cut from the same wafer.
  • Electrical connections can be made between the sensing arms of the push-pull half-bridge magnetic field sensor via lead connection pads.
  • Figure 9 is a schematic diagram of a reference half bridge sensor circuit.
  • the magnetoresistive sensor is a reference half-bridge magnetic field sensor including a sensing arm and a reference arm, and the reference arm is composed of a magnetoresistive element.
  • the reference half-bridge magnetic field sensor includes a sensing arm and a reference arm.
  • the absolute value of the slope of the response curve of the magnetoresistance of the sensing arm with the external field is much larger than the resistance of the reference arm with the external field.
  • the absolute value of the slope of the varying response curve is much larger than the resistance of the reference arm with the external field.
  • the reference half-bridge magnetic field sensor includes a sensor chip including 'X-Y The substrate of the surface and the magnetoresistive element constituting the sensor arm and the magnetoresistive element constituting the reference arm provided on the surface of the substrate.
  • Figure 10 is a schematic diagram of a half push-pull full-bridge magnetic field sensor circuit.
  • the magnetoresistive sensor is a semi-push-pull full-bridge magnetic field sensor consisting of two independent current drive sources and two sensor arms connected in full bridge.
  • the response curve of the magnetoresistance resistance of one of the semi-push-pull full-bridge magnetic field sensors with respect to the external field has an opposite tendency to the same external field with respect to the response curve of the magnetoresistance of the other sensor arm with the external field.
  • the semi-push-pull full-bridge magnetic field sensor includes two sensor chips, each of which includes 'X-Y A surface substrate and a sensor arm disposed on the surface of the substrate, wherein one sensor chip is arranged 180 degrees apart from the other sensor chip, and the two sensor chips are cut from the same wafer.
  • Figure 11 is a schematic diagram of a half-reference full-bridge sensor circuit.
  • a semi-reference full-bridge magnetic field sensor is constructed by two independent current drive sources, one sensing arm and one reference arm full bridge.
  • the absolute value of the slope of the response curve of the magnetoresistance of the sensor arm as a function of the external field is much larger than the absolute value of the slope of the response curve of the magnetoresistance of the reference arm as a function of the external field.
  • the semi-reference full bridge magnetic field sensor includes a sensor chip including the 'X-Y The substrate of the surface and the magnetoresistive element constituting the sensor arm and the magnetoresistive element constituting the reference arm provided on the surface of the substrate.
  • the 'push-pull full-bridge magnetic field sensor' 50 is used as an example.
  • the bridge contains four bridge arms that vary with the external field H sense . These bridge arms are defined as 'inductive arms'; pads for positive and negative bridge arms 27, 28 at the bottom of any one of the sensing arms 52. For the sake of clarity, these pads are not shown in the figure.
  • Sensing arm 52 and 52 'in response to the slope of the curve is positive RH sense, the same external field, the sensing arm 54 and 54' in response to the slope of the curve RH sense negative.
  • the direction of the arrows on 52 and 54 implies the sign of the slope of the respective RH sense curve.
  • the electrical pads of the push-pull full-bridge magnetic field sensor 50 which is arranged in a diamond shape from the top, are: bias voltage (Vbias, 45 ); right arm center pad (V2, 48); ground pad (GND, 46) and left arm center pad (V1, 47).
  • Sensor bridge arm on substrate 9 , 10 It is prepared and has electrical contacts on the substrate, the layout of which is shown in the figure above. There are many ways to connect the bridge arm to the external pads of the bridge. Typical connection structures include: chip-integrated connections, wire bond bonding, and solder ball connections.
  • the VH sense output curve 60 of the push-pull full-bridge magnetic field sensor 50 is shown in FIG. This curve is obtained from R H and R L of Figs. 3 and 4, and it is first necessary to calculate the variation of the output voltage V1-V2 with the external field H sense .
  • the values of the sensing arms (52, 52') and (54, 54') are R H and R L , respectively .
  • the resistance of the bridge circuit is:
  • the voltage V1 at the center point of the left bridge arm is:
  • the voltage V2 at the center of the right arm is:
  • the output of the bridge sensor is defined as:
  • H cross is a field that provides a magnetic bias field along the sensor plane perpendicular to the sensitive direction to bias the free layer magnetic moment.
  • H k is the net effective anisotropy energy of the free layer magnetic moment.
  • H k can be measured by an independent means such as a Vibrating Sample Magnetomete (VSM) or a Superconducting Quantum Interference Device (SQUID).
  • VSM Vibrating Sample Magnetomete
  • SQUID Superconducting Quantum Interference Device
  • the reference arms in the full bridge sensor 51 are 52, 52' and the reference arms are 53 and 53'. There is no arrow on the reference arm 53, indicating that the slope of its RH sense curve is very small.
  • the push-pull full-bridge sensor 50 has two types of sensor arms (52, 52') and (54, 54'), and the slopes of the RH sense curves of the two types of sensor arms are reversed.
  • the arrows above sensor arms 52 and 54 are the signs of the slope of the respective RH sense curves.
  • the push-pull full-bridge sensor 50 is compared to the reference full-bridge sensor 51. It has greater sensitivity because all the bridge arms contribute to the signal.
  • the push-pull half-bridge sensor 55 has two asymmetric sensing arms 52, 54.
  • the reference half bridge sensor 56 has only one sensing arm 52 and one reference arm 53.
  • the semi-push-pull full-bridge sensor 57 has two asymmetric sensing arms 52, 54 and two drive sources.
  • the half-push full-bridge magnetic field sensor is driven by drive source 59 instead of the bias voltage.
  • the semi-reference full bridge sensor 58 has a sensing arm 52, a reference arm 53, and two drive sources. 59.
  • the semi-reference magnetic field sensor is driven by drive source 59 instead of the bias voltage.
  • Push-pull full-bridge sensor 50 and reference full-bridge sensor 51 are shown in Figures 6 and 7.
  • the pads are clockwise, starting from the top: bias voltage (Vbias), center point of the right arm (V2), ground point (GND), and center point of the left arm (V1) ).
  • the external pads of these four bridge circuits can be connected to two different resistor arms.
  • the output voltage of the bridge circuit is usually measured by measuring the difference (V1-V2) between the V1 point and the V2 point by a voltmeter.
  • the push-pull half-bridge circuit sensor 55 and the reference half-bridge sensor 56 as shown in Figs. 8 and 9 have 3 The external pads are clockwise, starting from the top: bias voltage (Vbias), center point V1, and ground point (GND) through which the bridge circuit can be electrically connected.
  • Vbias bias voltage
  • GND ground point
  • the output voltages of the push-pull half-bridge sensor 55 and the reference bridge sensor 56 can be measured by a number of known methods.
  • One way is: Connect a voltmeter between the pads of V1 and GND.
  • the potential difference (V1-GND) between V1 and GND is the output voltage.
  • Another way is: at V1 and Vref
  • the voltmeter is connected between the pads (steady voltage supplied by an external circuit or device), and the potential difference (V1-Vref) between V1 and Vref is the output signal.
  • Vref It can be provided by a reverse biased diode, a voltage divider circuit or other known method.
  • the semi-push-pull full-bridge magnetic field sensor 57 and the semi-reference full-bridge sensor 58 as shown in Figures 10 and 11 have three external pads, clockwise, starting from the top: left half bridge and right half bridge.
  • the left half bridge consists of a constant current source I 1 ( 59 ), a center point V1 and a ground point GND.
  • the right half bridge consists of a constant current source I 2 ( 59 ' ), a center point V2 and a ground point GND.
  • Semi-push-pull full-bridge sensor 57 and semi-reference full-bridge sensor 58 The output voltage can be measured by a number of known methods. One method is to measure the output voltage of the bridge circuit by connecting the V1 point and the V2 point with a voltmeter and measuring the difference (V1-V2).
  • the steady current sources I 1 and I 2 in the half push-pull full bridge sensor 57 and the half reference full bridge sensor 58 can be implemented by a number of known methods.
  • One method is to monitor and adjust the voltage generated by a single magnetoresistive element of a set of magnetoresistive elements by a voltage controlled feedback loop, and the other is to utilize the output of one of a set of magnetoresistive elements.
  • This method needs to satisfy the resistance of a group of magnetoresistive elements much larger than the resistance of a single magnetoresistive element.
  • the resistance of the bridge circuit changes, and the voltage of the bridge circuit changes accordingly, because the energy of the circuit is provided by a steady current source instead of a voltage source.
  • the 'reference arm 53' is mentioned in the reference full bridge sensor 52, the reference half bridge sensor 56 and the half reference full bridge sensor 58.
  • the so-called reference arm 53 has a very low sensitivity with respect to the sensing arm, and appears on the response curve as being within the operating range of the sensor, and the absolute value of the slope of the response curve of the sensing arm is much larger than that of the reference arm 53. It is not practical to change the ⁇ R/R of the reference and sensing elements, so the sensitivity can be changed by changing H s . This approach can be achieved through a combination of several different technologies:
  • Magnetic Shielding - deposits a high permeability ferromagnetic layer on the reference arm to attenuate the effect of the applied magnetic field.
  • Shape Anisotropy Energy Since the reference element and the sensing element have different sizes, they have different shape anisotropy energies. The most common practice is to make the long axis length of the reference element larger than the long axis length of the sensing element, and the short axis length is smaller than the short axis length of the sensing element, so that the demagnetization effect of the reference element parallel to the sensitive direction is much larger than that of the sensing element.
  • the antiferromagnetic layer 1 (AF1) and the antiferromagnetic layer 2 (AF2) are antiferromagnetic materials, such as PtMn, IrMn, FeMn.
  • Ferromagnetic layer (FM) uses some representative ferromagnetic or multilayer films composed of ferromagnetic alloys, including but not limited to NiFe, CoFeB, CoFe and NiFeCo.
  • the insulating layer may be any insulating material capable of spin polarization, such as aluminum oxide or magnesium oxide.
  • the barrier layer is typically a thin film of non-ferromagnetic material such as Ta, Ru or Cu.
  • Antiferromagnetic layer AF1 The antiferromagnetic blocking temperature is lower than that of AF2, making the ferromagnetic layer /Ru/ The bias field of the pinned layer of the ferromagnetic layer structure and the bias field of the free layer are orthogonal to each other.
  • Permanent magnet bias in this technique, Fe, Co, Cr and Pt
  • a permanent magnet alloy material is deposited onto the surface of the sensing element or the magnetic tunnel junction to provide a magnetic field to bias the MTJ
  • the response curve of the component One advantage of permanent magnet bias is that a large magnetic field can be used to initialize the permanent magnet after the bridge is constructed. Another very important advantage is that the bias field can eliminate MTJ. The magnetic domain of the component to stabilize and linearize the output of the MTJ component. The great advantage of this design is its great flexibility in design adjustment.
  • the following is a multilayer film structure that can be implemented:
  • the magnetoresistive sensor 70 is fixed in the middle of the two on-chip permanent magnets 71.
  • the top layer of the structure on the bottom of the semiconductor substrate is not clearly visible.
  • the strip permanent magnets have a gap (Gap) 72, a width (W) 73, a thickness (t) 74 and a length (Ly) 75.
  • the strip permanent magnets are designed to provide a cross-bias field perpendicular to the sensitive axis (Y-axis) 76, primarily in the plane of the substrate. This axis is called the cross axis or directly called the X axis 78.
  • the magnetoresistive element 70 is designed to have an elliptical shape having a width W MR 82 and a length L MR 83. The portion passing through the magnetoresistive element 70 is shown in Fig. 1.
  • the strip-shaped permanent magnets are usually magnetized in a large magnetic field at the initial stage, so their remanence M PM 77 is mainly perpendicular to the sensitive axis 76, largely to the field parallel to the X-axis 78, and is located at XY. In-plane.
  • the X and Y axes are standard orthogonal Cartesian axes, and the Z axis is the normal direction of the substrate.
  • Figure 14 shows the projection of the magnetic line in the XZ plane. The size and direction of these fields can be calculated.
  • the magnetic field of the strip permanent magnet is considered to be the result of the virtual magnetic charge and magnetization boundary conditions formed by the edges 90 and 91 of the magnet as shown in FIG.
  • the direction of the remanence M PM 77 is at an angle ⁇ PM 92 with respect to the sensitive axis (Y-axis) 76.
  • the magnitude of the magnetic charge varies with the magnitude and direction of the remanence M PM 77 and the angle ⁇ PM 92 and is related to the inclination angle of the strip permanent magnet (' ⁇ ref ' or ' ⁇ sns '):
  • the final magnetic field on the face of the magnetoresistive element 70 between the two strip-shaped permanent magnets 71 is a vector H gap 94 .
  • the component direction of the field is mainly perpendicular to the edge of the strip permanent magnet 71.
  • Field 94' is copied to the right side of the figure for comparison.
  • the angle ⁇ gap between the H gap and the X axis satisfies:
  • Equation 19 is a function of W73 and gap72 shown in Fig. 16, which represents the saturation field of the reference element and the sensing element, which can be changed by changing the shape dimension of the magnet 71.
  • MTJ element using the same, and three-dimensional size MTJ bar permanent magnet film on the reference element and the sensing element, the H cross 100 is 6.5 times the effect of H sense 101, the reference saturation field element is 6.5 times the sensing element .
  • This ratio is sufficient for the bridge with reference arm 53 and can be increased to 10 by appropriate design.
  • Figure 17 is a schematic illustration of the magnetic field component around the magnetoresistive element of Figure 16. Including H cross 95, H off 96 and its combined vector H gap 94'. The figure shows that by setting the angle between the edge of the strip-shaped permanent magnet 71 and the sensitive direction, H cross 95 and the offset field H off 96 can be simultaneously generated for: (1) setting the saturation field value of the magnetoresistive element 70 , eliminating its offset field H O 23 ; (2) Optimizing the symmetry, offset, and sensitivity of the bridge output.
  • the remanence M PM 77 and the angle ⁇ PM 92 of the sensitive direction are set so that after the sensor chip is prepared, a fine adjustment device can be provided to minimize the offset value or symmetry, which can improve the product yield.
  • the magnetoresistive element 70 has an elliptical profile with a long axis L MR 83 longer than the minor axis W MR 82, and the major axis and the minor axis respectively and Y Axis 76 and X-axis 78 are parallel.
  • the magnetoresistive element When the magnetoresistive element operates, it is subjected to the net vector field H MR 104 as shown in Fig. 15, and the external field and the X axis have an angle ⁇ MR 105 , which can generate the net magnetic energy M MR of the free layer 6 of the magnetoresistive element 70. 106.
  • the M MR 106 has an angle ⁇ MR 107 with respect to the X axis.
  • Sensitivity is defined as the first derivative (slope) of the RH sense curve at zero field strength, which can be calculated by the following method:
  • (1) consisting of a magnetic magnetoresistive element found can function with respect to H MR, M MR's, H MR, M MR function with respect to ⁇ MR and ⁇ MR;
  • the second spontaneous magnetization field consists of two uniaxial fields with constants in X, Y, and Z: one is the demagnetizing field (d) The other is the material anisotropy energy (k).
  • H MR is completely along the Y axis
  • Figure 18 is a plot of sensitivity (V/V/Oe) as a function of H cross /H k (dimensionless). It can be seen that as H cross /H k decreases to 1, the calculated value of sensitivity increases infinitely. In fact, H cross is set to be slightly higher than H k , which makes the sensing area of the sensor wider, while reducing the hysteresis and avoiding other magnetic fields, so that the M MR of the free layer is not saturated.
  • the magnetoresistive element is fabricated on a circular substrate, called a wafer.
  • the wafer can be cut into single or two magnetoresistive elements to electrically connect the bridge. , then encapsulation.
  • Figure 19 shows the use of the magnetoresistive element 70 as shown in Figures 16 and 13.
  • the layout of the push-pull full-bridge sensor chip Two identical chips 122 and 123 are cut from the same wafer and packaged as a single sensor. Two chips rotate relative to each other with respect to the Z axis 180 °, its sensitive surface is the X-Y plane. Each chip has two electrically isolated magnetoresistive sensing arms.
  • Push-pull full-bridge sensor 50 through lead 125 Make an electrical connection. Rectangular pads are located at the edge of each chip, except that one wire position is circular to facilitate intuitive determination of the number and direction of each die pad. Each circuit has two pads on its node (a total of 8 One) for internal bridge connections and the other for external devices. This allows the pads on top of the chip 122 to be connected by lead wires to the package leads and the PCB of the lead frame.
  • the long axis of the component is along the direction of the sensitive axis.
  • the strip-shaped permanent magnets on the chip are arranged obliquely with a width W73, the spacing between the two magnets is Gap72, and the tilt angle is ⁇ sns 93 .
  • These magnets provide a magnetic bias field to saturate the sensing element when the additional provided H off satisfies H off -H o > H sat (this is necessary for a push-pull bridge to exhibit its linear operating state), at the top right
  • the negative magnetoresistive 54' is connected between GND and V2, and the upper left negative magnetoresistive 54 is connected between Vbias and V1.
  • the RH sense response curves of magnetoresistances 54 and 54' are shown in inset 120 and have a high impedance state in the negative direction of the external field H sense .
  • Figure 20 is a layout view of the reference full bridge sensor 51, which is provided with inclined strip-shaped permanent magnets having different widths, angles, and intervals between the sensing arm and the reference arm.
  • the magnetics constituting the reference arm The long axis of the resistive element is perpendicular to the Y axis of the sensitive axis, and the length in the X-axis direction is greater than the length of the magnetoresistive element constituting the sensing arm in the X-axis direction, so that the demagnetization effect of the reference arm parallel to the sensitive direction is much greater than the induction arm.
  • the reference arm and the sensing arm are prepared once on the substrate, and the reference bridge can be electrically connected by depositing wires or wire bonds on the substrate to form a bridge structure, and the reference full bridge sensor is cut from the wafer.
  • this structure Located on a substrate, this structure is called a 'monolithic sensor'.
  • the monolithic sensor simplifies the fabrication process while reducing the size of the sensor compared to multi-chip packaged sensors.
  • the MTJ component string is located in the middle of the strip-shaped permanent magnets with different inclinations, and 115, 116, 117 and 118 are the bridge arms of the bridge.
  • Optimizing the offset to zero can also adjust the number of MTJ components on the reference and sensing arms, or just optimize the offset of the reference or sensing arm.
  • a rectangular shield 119 as shown by the dashed line is also an alternative method. The role of the shield is to further reduce the effective sensitivity of the reference arms 115 and 116.
  • the magnetoresistive sensor used to measure the magnetic field enables mass production, has a higher sensitivity for measuring magnetic fields, and has low power consumption and small size.

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Abstract

本发明涉及一种用于测量磁场的磁电阻传感器。本发明提供了磁电阻传感元件的灵敏度的计算，该灵敏度与形状各向异性能及外场相关。磁电阻元件的长轴与敏感方向平行，同时具有一个垂直敏感方向的外场分量Hcross可以进一步饱和磁电阻元件的磁矩。单片永磁体的作用是产生具有角度的Hcross场同时抵消沿易磁化轴方向的非理想场。高灵敏度磁电阻元件可以广泛应用在电气领域。本发明将会对其构成的六种电桥形式进行阐述。

Description

用于测量磁场的磁电阻传感器
技术领域
本发明涉及了一种磁电阻传感器，尤其为一种用于测量磁场的磁电阻传感器。
背景技术
磁性传感器广泛用于现代***中以测量或感应磁场强度、电流、位置、运动、方向等物理参数。在现有技术中，有许多不同类型的传感器用于测量磁场和其他参数。但是，他们都受到了现有技术中的各种众所周知的限制，例如，尺寸过大，灵敏度低，动态范围窄，成本高，可靠性低以及其他因素。因此，持续地改进磁传感器，特别是改进易与半导体器件或集成电路整合的传感器及其制造方法是有必要的。
隧道结磁电阻传感器具有高灵敏度，尺寸小，成本低以及功耗低等优点。尽管 MTJ 传感器与半导体标准制造工艺相兼容，但是高灵敏度的 MTJ 传感器并没有实现低成本大规模生产。特别是传感器的成品率取决于 MTJ 元件磁阻输出的偏移值，构成电桥的 MTJ 的磁阻很难达到高的匹配度，同时正交磁场传感器在同一半导体基片上集成的制造工艺非常复杂。
可用于传感器的磁电阻元件的响应是由传感材料构成的多层膜的磁化方向的函数。为了获得磁感应通常需要一个外场对磁矩进行偏置使其工作在一个稳定灵敏的工作点上。这种偏置方式通常是采用外加线圈或者永磁体，这些设计从功耗、成本和大规模制造的角度来看是不可取的。
发明内容
针对上述问题，本发明提供一种用于测量磁场的磁电阻传感器，能够实现大规模生产，测量磁场的灵敏度更高，同时具备功耗低、尺寸小的特点。
本发明公开了一种用于测量磁场的磁电阻传感器，它包括：
基片，该基片具有一' X-Y '表面，磁电阻传感器的敏感轴平行于 Y 轴， X 轴垂直于 Y 轴；
至少一个感应臂，由磁电阻元件构成，磁电阻元件设置在基片的' X-Y '表面上，磁电阻元件沿 Y 轴方向的长度大于其沿 X 轴方向的长度；
多个设置在磁电阻传感器的基片上的条形永磁体，相邻两个条形永磁体之间形成间隙磁场，该间隙磁场具有沿 X 轴和 Y 轴的分量；
焊盘，设置在感应臂的末端，可以通过其将感应臂相电连。
优选地，至少一个磁电阻元件被间隙磁场在 X 轴方向饱和。
优选地，磁电阻传感器的磁电阻阻值随外场变化的响应曲线在磁电阻传感器的工作区间内具有高线性度、高斜率值、低磁滞。
优选地，对条形永磁体充磁来调节该条形永磁体的磁化强度和方向，以调节磁电阻传感器的输出性能。
优选地，磁电阻元件为 MTJ 元件或 GMR 元件。
优选地，该磁电阻传感器为桥式磁场传感器。
进一步优选地，桥式磁场传感器为推挽全桥磁场传感器。
更进一步优选地，推挽全桥磁场传感器包括四个感应臂，在磁电阻传感器的工作区间内其中两个感应臂的磁电阻阻值随外场变化的响应曲线相对另外两个感应臂的磁电阻阻值随外场变化的响应曲线在相同的外场作用下具有相反的变化趋势。
更进一步优选地，推挽全桥磁场传感器包括两个传感器芯片，每个传感器芯片包括具有' X-Y '表面的基片和设置在基片的表面上的两个感应臂，其中一个传感器芯片相对另一个传感器芯片以旋转 180 度的方式排布，两个传感器芯片由同一晶圆切割制成。
再进一步优选地，感应臂之间可通过引线连接焊盘实现电连。
进一步优选地，桥式磁场传感器为参考全桥磁场传感器，该参考全桥磁场传感器包括感应臂和参考臂，每个参考臂由磁电阻元件构成。
更进一步优选地，参考全桥磁场传感器包括两个感应臂和两个参考臂，在磁电阻传感器的工作区间内，感应臂的磁电阻阻值随外场变化的响应曲线的斜率绝对值远大于参考臂的磁电阻阻值随外场变化的响应曲线的斜率绝对值。
更进一步优选地，参考全桥磁场传感器包括一个传感器芯片，该传感器芯片上包括具有' X-Y '表面的基片和设置在基片表面上的构成感应臂的磁电阻元件和构成参考臂的磁电阻元件。
再进一步优选地，构成参考臂的磁电阻元件沿 X 轴方向的长度大于其沿 Y 轴方向的长度，且其沿 X 轴方向的长度大于构成感应臂的磁电阻元件沿 X 轴方向的长度。
再进一步优选地，构成参考臂的磁电阻元件的表面覆盖有一层高磁导率的铁磁屏蔽层。
优选地，设置在参考臂附近的条形永磁体在 X 轴方向的磁场分量大于设置在传感臂附近的条形永磁体在 X 轴方向的磁场分量。
再进一步优选地，构成参考臂或感应臂的磁电阻元件上设置有一层膜或多层膜构成的永磁偏置层。
再进一步优选地，构成参考臂的磁电阻元件上设置有一层膜或多层膜构成的交换偏置层。
进一步优选地，桥式磁场传感器为推挽半桥磁场传感器，该推挽半桥磁场传感器由两个感应臂构成。
更进一步优选地，推挽半桥磁场传感器包括两个感应臂，在磁电阻传感器的工作区间内其中一个感应臂的磁电阻阻值随外场变化的响应曲线相对另一个感应臂的磁电阻阻值随外场变化的的响应曲线在相同的外场作用下具有相反的变化趋势。
更优选地，推挽半桥磁场传感器包括两个传感器芯片，每个传感器芯片包括具有' X-Y '表面的基片和设置在基片表面上的感应臂，其中一个传感器芯片相对另一个传感器芯片以旋转 180 度的方式排布，两个传感器芯片由同一晶圆切割制成。
再进一步优选地，推挽半桥磁场传感器的感应臂之间可通过引线连接焊盘实现电连。
进一步优选地，该磁电阻传感器为参考半桥磁场传感器，该参考半桥磁场传感器包括感应臂和参考臂，每个参考臂由磁电阻元件构成。
更进一步优选地，参考半桥磁场传感器包括一个感应臂和一个参考臂，在磁电阻传感器的工作区间内感应臂的磁电阻阻值随外场变化的响应曲线的斜率绝对值远大于参考臂的磁电阻阻值随外场变化的响应曲线的斜率绝对值。
更优选地，参考半桥磁场传感器包括一个传感器芯片，该传感器芯片包括具有' X-Y '表面的基片和设置在基片表面上的构成感应臂的磁电阻元件和构成参考臂的磁电阻元件。
再进一步优选地，构成参考臂的磁电阻元件沿 X 轴方向的长度大于其沿 Y 轴方向的长度，且其沿 X 轴方向的长度大于构成感应臂的磁电阻元件沿 X 轴方向的长度。
优选地，构成参考臂的磁电阻元件的表面覆盖有一层高磁导率的铁磁屏蔽层。
再进一步优选地，设置在参考臂附近的条形永磁体在 X 轴方向的磁场分量大于设置在传感臂附近的条形永磁体在 X 轴方向的磁场分量。
再进一步优选地，构成参考臂或感应臂的磁电阻元件上设置有一层膜或多层膜构成的永磁偏置层。
再进一步优选地，构成参考臂的磁电阻元件上设置有一层膜或多层膜构成的交换偏置层。
进一步优选地，该磁电阻传感器为由两个独立的电流驱动源和两个感应臂全桥连接构成的半推挽全桥磁场传感器。
更进一步优选地，半推挽全桥磁场传感器中的一个感应臂的磁电阻阻值随外场变化的响应曲线相对另一个感应臂的磁电阻阻值随外场变化的响应曲线在相同的外场具有相反的变化趋势。
更优选地，半推挽全桥磁场传感器包括两个传感器芯片，每个传感器芯片包括具有' X-Y '表面的基片和设置在基片表面上的感应臂，其中一个传感器芯片相对另一个传感器芯片以旋转 180 度的方式排布，两个传感器芯片由同一晶圆切割制成。
再进一步优选地，半推挽全桥磁场传感器的感应臂之间可通过引线连接焊盘实现电连。
进一步优选地，该磁电阻传感器为由两个独立的电流驱动源、一个感应臂和一个参考臂全桥连接构成的半参考全桥磁场传感器。
更进一步优选地，感应臂的磁电阻阻值随外场变化的响应曲线的斜率绝对值远大于参考臂的磁电阻阻值随外场变化的响应曲线的斜率绝对值。
更进一步优选地，半参考全桥磁场传感器包括一个传感器芯片，该传感器芯片包括具有' X-Y '表面的基片和设置在基片表面上的构成感应臂的磁电阻元件和构成参考臂的磁电阻元件。
再进一步优选地，构成参考臂的磁电阻元件沿 X 轴方向的长度大于其沿 Y 轴方向的长度，且其沿 X 轴方向的长度大于构成感应臂的磁电阻元件沿 X 轴方向的长度。
再进一步优选地，构成参考臂的磁电阻元件的表面覆盖有一层高磁导率的铁磁屏蔽层。
再进一步优选地，设置在参考臂附近的条形永磁体在 X 轴方向的磁场分量大于设置在传感臂附近的条形永磁体在 X 轴方向的磁场分量。
再进一步优选地，构成参考臂或感应臂的磁电阻元件上设置有一层膜或多层膜构成的永磁偏置层。
再进一步优选地，构成参考臂的磁电阻元件上设置有一层膜或多层膜构成的交换偏置层。
本发明提供了一种标准半导体制造工艺、用于规模生产的线性桥式磁电阻传感器。该传感器采用高灵敏度的磁电阻传感元件例如隧道结磁电阻（ MTJ ）或者巨磁电阻（ GMR ）多层膜。单片永磁体用来产生散场，以提供偏置场，从而抵消传感元件的非理想磁行为。永磁体产生的偏置场可以平衡内部的沿敏感方向的形状和材料的各向异性能，同时交叉轴磁偏置场可以优化传感器的灵敏度。因此高灵敏度磁场敏感元件可通过连接成电桥形式进一步加强其低偏移，高线性度，好的温度稳定性以拓宽其适用的领域。
附图说明
图 1 是一个隧道结磁电阻（ MTJ ）的横截面示意图，在 MTJ 元件的顶电极层和底电极层之间连接有欧姆表显示其阻值变化。
图 2 是自旋阀元件参考层沿难轴方向磁化的磁电阻响应示意图。
图 3 是 MTJ 元件的响应曲线图，
图 4 是旋转 180 °的后的 MTJ 元件在同一外场作用下（ flipped die ）的响应曲线图。
图 5 是将多个 MTJ 元件连接为一个磁电阻元件的示意图。
图 6 是推挽全桥传感器的电路示意图。
图 7 是参考全桥传感器的电路示意图。
图 8 是推挽半桥传感器的电路示意图。
图 9 是参考半桥传感器的电路示意图。
图 10 是半推挽全桥磁场传感器的电路示意图。
图 11 是半参考全桥传感器的电路示意图。
图 12 是桥式电路随外场变化的输出电压模拟示意图，该桥式电路由四个高灵敏度的 MTJ 元件的桥臂翻转排列构成。
图 13 标示了集成永磁体摆放的位置。永磁体相对于 MTJ 传感元件的长轴以及敏感轴平行。
图 14 是图 13 所示的永磁体和 MTJ 元件的截面图以及一对永磁体的磁感线分布。
图 15 是通过设置 MTJ 元件周围的场强和方向的角度来控制其响应曲线的偏移和饱和场。
图 16 是传感元件所处的一对片式永磁体中间的磁场分布，磁场强度是磁体宽度和磁体间距的函数。
图 17 是图 16 中的磁电阻元件周围的磁场分量示意图。
图 18 是灵敏度关于 Hcross/Hk 的函数图。
图 19 是两个芯片翻转排列的传感器设计布局图，每一块芯片都有两个传感臂，两块芯片构成一全桥。相同的两块芯片沿基片标准轴旋转 180 °排列。
图 20 是一种规范的参考桥式传感器芯片布局图，该设计利用倾斜的永磁体设置传感臂的偏置场，竖直排列的永磁体设置参考臂的偏置场以优化电桥的输出，同时可以选择性地设置屏蔽层。
具体实施方式
图 1 是隧道结磁电阻（ Magnetic Tunnel Junctions, MTJ ）元件的结构和电子测量原理图。 MTJ 元件 1 由钉扎层 2 、隧道势垒层 5 、铁磁层（敏感层） 6 构成。钉扎层 2 由铁磁层（被钉扎层） 4 和反铁磁层 3 构成，铁磁层 4 和反铁磁层 3 之间的交换耦合作用决定了铁磁层 4 的磁化方向；隧道势垒层 5 通常由 MgO 或 Al2O3 形成，位于铁磁层 4 的上部。铁磁层 6 位于隧道势垒层 5 的上部。箭头 8 和箭头 7 分别代表被钉扎层 4 和敏感层 6 的磁化方向。被钉扎层 4 的磁矩方向 8 在一定大小的磁场作用下是相对固定的，敏感层 6 的磁矩方向 7 相对于被钉扎层 4 的磁矩方向 8 的是相对自由且可旋转的。 3 、 4 、 5 、 6 指示的各层的典型厚度为 0.1 nm 到 100 nm 之间。
底电极层 16 和顶电极层 17 直接与相关的反铁磁层 3 和敏感层 6 电接触。电极层通常采用非磁性导电材料，能够携带电流输入欧姆计 18 。欧姆计 18 适用于已知的穿过整个隧道结的电流，并对电流（或电压）进行测量。通常情况下，隧道势垒层 5 提供了器件的大多数电阻，约为 1000 欧姆，而所有导体的阻值约为 10 欧姆。底电极层 16 位于绝缘基片 9 上方，绝缘基片 9 要比底电极层 16 要宽，其位于其他材料构成的底基片 10 的上方。底基片的材料通常是硅、石英、耐热玻璃、 GaAs 、 AlTiC 或者是能够于晶圆集成的任何其他材料。硅由于其易于加工为集成电路（尽管磁性传感器不总是需要这种电路）成为最好的选择。
适合线性磁场测量的 GMR 或 MTJ 元件的输出图如图 2 所示。响应曲线 20 在低阻态 21 和高阻态 22 处饱和， RL 和 RH 分别代表低阻态和高阻态的阻值。响应曲线 20 在饱和场之间的区域是随外场 Hsense 线性变化的。外场 Hsense 平行于传感元件的敏感轴。被钉扎层 4 的磁矩方向 8 与敏感轴反平行意味着其指向 -H 的方向。当自由层 6 的磁矩方向 7 与被钉扎层 4 的磁矩方向 8 反平行时，磁电阻元件的响应曲线 20 为最大值，当两者平行时，为最小值。磁电阻响应曲线 20 的中间值随自由层 6 和被钉扎层 4 之间的角度的变化而变化。响应曲线 20 不是沿 H=0 的点对称的。饱和场 25 、 26 是沿着 HO 点 23 典型的偏移场，因此 RL 值对应的饱和场更接近 H=0 的点。 HO 值通常被称为'橘子皮效应（ Orange Peel ）'或'奈尔耦合（ Neel Coupling ）'，其典型值为 1 到 40 Oe ，其具体数值与磁电阻元件中铁磁性薄膜的结构和平整度有关，依赖于材料和制造工艺。
如图 2 所示的响应曲线在饱和场 25 和 26 之间的区域的工作状态可以近似为方程：
Figure PCTCN2013071676-appb-I000001
, (1)
其中， HS 是饱和场。 HS 被定量地定义为线性区域的切线与正负饱和曲线的切线的交点对应的值，该值是在响应曲线相对于 HO 点的不对称性消除的情况下所取的。
图 2 所示的是在理想情况下的响应曲线 20 。在理想状态下，磁电阻 R 随外场 Hsense 的变化是完美的线性关系，同时没有磁滞（在实际情况下，磁电阻的响应曲线随外场变化具有滞后的现象，我们称之为磁滞。磁电阻的响应曲线为一个回路，通常作为应用的磁电阻材料的磁滞很小，在实际使用中可以看做一个完美的线性曲线）。在实际应用的传感器领域，由于磁传感器设计的制约以及材料的缺陷，这条曲线 20 会更弯曲。本发明涉及了传感器的设计、结构以及能够生产实施的工序，该传感器具有卓越的工作感应，在工作区域内同时具有高线性度、低磁滞、高灵敏度的特点（即磁电阻响应曲线斜率大）。
R-Hsense 曲线 30 具有低阻态 21 的阻值 RL 和高阻态 22 的阻值 RH 。其高灵敏度的区域是在零场附近，传感器的工作区间位于零场附近，约为饱和场 25 和 26 之间 1/3 的区域。曲线 30 在 H=0 点处的切线为 33 。 该曲线的斜率和传感器的灵敏度成正比。零场切线 33 分别和低场切线 34 以及高场切线 35 相交于点 25 （ -HS+HO) 和点 26 （ HS+HO ）。如图 3 所示，当磁矩方向 7 与磁矩方向 8 反平行时，曲线 30 对应高阻态；当磁矩方向 7 和磁矩方向 8 平行时，曲线 30 对应低阻态。当 7 和 8 垂直时，阻值是位于 RL 和 RH 之间的中间值，这是理想的线性磁传感器的'工作点'。如图 4 所示，另一个磁电阻 R 与外场 Hsense 的变化曲线，该磁电阻是沿传感器的法线旋转了 180 °。在同一外场 Hsense 的作用下，该磁电阻 R 和被钉扎层 4 的矢量磁矩方向 8 是平行于外场 Hsense 的。在这种情况下，旋转的芯片的 R-Hsense 的斜率为负值。普通摆放的磁电阻和旋转 180 °设置的磁电阻可以构造电桥，这被证明比其他可能的方法输出值更大。
由于尺寸小， MTJ 元件能够连接成串以增加灵敏度，噪声减少至 1/F ，同时可以提高其 ESD 性能，其实施方式见图 5 。这些磁电阻元件串被用来作为更为复杂的电路结构的磁电阻臂。 MTJ 元件 40 在底电极层 41 和顶电极层 42 中间成三明治结构，内部的电流 43 垂直通过 MTJ 元件 40 水平方向交替流过顶电极层和底电极层。底电极层 41 在绝缘层 9 的上方，而绝缘层 9 位于底基片 10 上。在每个元件串的末端是焊盘，也就是电阻臂和其他元件例如欧姆计 18 连接的地方，或者此电路上的部件通过此焊盘可以和芯片上其他电路的部件连接，而没有任何其他的连接方式。在通常情况下，电流流动的方向并不对桥臂电阻的有效电阻产生影响。保持参考臂和感应臂的 MTJ 元件的尺寸相同是有利的，因为这会导致器件的刻蚀偏置不敏感，同时参考臂和感应臂的 MTJ 元件串的电阻值是可以根据 MTJ 元件个数设置来改变的。
电桥是用来改变磁电阻传感器的信号的，使其输出电压便于被放大。这可以改变信号的噪声，取消共模信号，减少温漂或其他的不足。上述的 MTJ 元件串可以连接构成惠斯通电桥或其他电桥。
图 6 是推挽全桥传感器电路的示意图。推挽全桥磁场传感器包括四个感应臂，在磁电阻传感器的工作区间内，其中两个感应臂的磁电阻阻值随外场变化的响应曲线相对另外两个感应臂的磁电阻阻值随外场变化的响应曲线在相同的外场作用下具有相反的变化趋势。
推挽全桥磁场传感器包括两个传感器芯片，每个传感器芯片包括具有' X-Y '表面的基片和设置在基片表面上的两个感应臂，其中一个传感器芯片相对另一个传感器芯片以旋转 180 度的方式排布，两个传感器芯片由同一晶圆切割制成。
感应臂之间可以通过引线连接焊盘实现电连。
图 7 是参考全桥传感器电路的示意图。
桥式磁场传感器为参考全桥磁场传感器，该参考全桥磁场传感器包括感应臂和参考臂，每个参考臂由磁电阻元件构成。
参考全桥磁场传感器包括两个感应臂和两个参考臂，在磁电阻传感器的工作区间内，感应臂的磁电阻阻值随外场变化的响应曲线的斜率绝对值远大于参考臂的磁电阻阻值随外场变化的响应曲线的斜率绝对值。
参考全桥磁场传感器包括一个传感器芯片，该传感器芯片包括具有' X-Y '表面的基片和设置在基片表面上的构成感应臂的磁电阻元件和构成参考臂的磁电阻元件。
图 8 是推挽半桥传感器电路的示意图。
桥式磁场传感器为推挽半桥磁场传感器，该推挽半桥磁场传感器由两个感应臂构成。
推挽半桥磁场传感器包括两个感应臂，在磁电阻传感器的工作区间内，其中一个感应臂的磁电阻阻值随外场变化的响应曲线相对另一个感应臂的磁电阻阻值随外场变化的的响应曲线在相同的外场作用下具有相反的变化趋势。
推挽半桥磁场传感器包括两个传感器芯片，每个传感器芯片包括具有' X-Y '表面的基片和设置在基片表面上的感应臂，其中一个传感器芯片相对另一个传感器芯片以旋转 180 度的方式排布，两个传感器芯片由同一晶圆切割制成。
推挽半桥磁场传感器的感应臂之间可以通过引线连接焊盘实现电连。
图 9 是参考半桥传感器电路的示意图。
该磁电阻传感器为参考半桥磁场传感器，该参考半桥磁场传感器包括感应臂和参考臂，参考臂由磁电阻元件构成。
参考半桥磁场传感器包括一个感应臂和一个参考臂，在磁电阻传感器的工作区间内感应臂的磁电阻阻值随外场变化的响应曲线的斜率绝对值远大于参考臂的磁电阻阻值随外场变化的响应曲线的斜率绝对值。
参考半桥磁场传感器包括一个传感器芯片，该传感器芯片上包括' X-Y '表面的基片和设置在基片表面上的构成感应臂的磁电阻元件和构成参考臂的磁电阻元件。
图 10 是半推挽全桥磁场传感器电路的示意图。
该磁电阻传感器为由两个独立的电流驱动源和两个感应臂全桥连接构成的半推挽全桥磁场传感器。
半推挽全桥磁场传感器中的一个感应臂的磁电阻阻值随外场变化的响应曲线相对另一个感应臂的磁电阻阻值随外场变化的响应曲线在相同的外场具有相反的变化趋势。
半推挽全桥磁场传感器包括两个传感器芯片，每个传感器芯片包括具有' X-Y '表面的基片和设置在基片表面上的感应臂，其中一个传感器芯片相对另一个传感器芯片以旋转 180 度的方式排布，两个传感器芯片由同一晶圆切割制成。
半推挽全桥磁场传感器的感应臂之间可以通过引线连接焊盘实现电连。
图 11 是半参考全桥传感器电路的示意图。
由两个独立的电流驱动源、一个感应臂和一个参考臂全桥连接构成了半参考全桥磁场传感器。
感应臂的磁电阻阻值随外场变化的响应曲线的斜率绝对值远大于参考臂的磁电阻阻值随外场变化的响应曲线的斜率绝对值。
半参考全桥磁场传感器包括一个传感器芯片，该传感器芯片包括具有' X-Y '表面的基片和设置在基片表面上的构成感应臂的磁电阻元件和构成参考臂的磁电阻元件。
以电桥形式为'推挽全桥磁场传感器' 50 为例，该电桥含有四个随外场 Hsense 变化的桥臂，这些桥臂被定义为'感应臂'；正负桥臂的焊盘 27 、 28 在任意一个感应臂 52 的底部。为清晰起见，这些焊盘在图中并未标示。感应臂 52 和 52' 的响应曲线 R-Hsense 的斜率为正值，同一外场作用下，感应臂 54 和 54' 的响应曲线 R-Hsense 的斜率为负值。位于 52 和 54 上的箭头的方向暗示了各自的 R-Hsense 曲线的斜率的符号。
从顶端开始顺着圆周呈菱形排列的推挽全桥磁场传感器 50 的电焊盘为：偏置电压（ Vbias, 45 ）；右臂中心焊盘（ V2, 48 ）；地线焊盘（ GND, 46 ）以及左臂中心焊盘（ V1, 47) 。传感器桥臂在基片 9 、 10 上制备且具有基片上的电触点，其布局图如上图所示。有很多种方式连接电桥臂和电桥的外接焊盘。典型的连接结构包括：芯片集成连接、绑线键合以及焊球连接。
推挽全桥磁场传感器 50 的 V-Hsense 输出曲线 60 如图 12 所示。由附图 3 和附图 4 的 RH 和 RL 得到该曲线，首先需要计算输出电压 V1-V2 随外场 Hsense 的变化。在这种情况下，感应臂（ 52 、 52' ）以及（ 54 、 54' ）的值分别为 RH 和 RL 。电桥电路的阻值为：
Figure PCTCN2013071676-appb-I000002
, (2)
当左右桥臂具有相同的阻值，电流通过左右两侧电桥之后被平分：
Figure PCTCN2013071676-appb-I000003
, (3)
左桥臂中心点的电压 V1 为：
Figure PCTCN2013071676-appb-I000004
, (4)
右桥臂中心点的电压 V2 为：
Figure PCTCN2013071676-appb-I000005
, (5)
桥式传感器的输出被定义为：
Figure PCTCN2013071676-appb-I000006
, (6)
因此，输出电压 V 在正场方向上的最大值如图 12 所示为 +Vpeak 61 。可以看到切线 63 穿过原点和 +Vpeak61 相交于 Hsense=Hsat 的点。因此，桥式电路的输出灵敏度被定义为桥式电路的输出在 H=0 的点的一阶导数：
Figure PCTCN2013071676-appb-I000007
, (7)
而，
Figure PCTCN2013071676-appb-I000008
, (8)
其中 Hcross 是沿着传感器平面垂直于敏感方向为其提供磁偏置场以偏置自由层磁矩的场。 Hk 是自由层磁矩的净有效各向异性能。 Hk 可以通过独立的方式例如震动样品磁强计（ Vibrating Sample Magnetomete, VSM ）或超导量子干涉仪（ Superconducting Quantum Interference Device, SQUID ）进行测量。此时我们替将方程 8 代入方程 7 可以得到灵敏度的 V-Hsense 曲线，如图 12 所示：
Figure PCTCN2013071676-appb-I000009
, (9)
前面我们已经详细描述了推挽全桥传感器 50 的灵敏度的计算。
接下来将针对相关的六种电桥形式的灵敏度做一个表格进行对比，此处省略完全的推导过程。电桥的结构如图 6-11 所示。其相对应的灵敏度和峰值电压如表 1 。
电桥类型 峰值电压 灵敏度
推挽全桥传感器 50
Figure PCTCN2013071676-appb-I000011
参考全桥传感器 51
Figure PCTCN2013071676-appb-I000012
Figure PCTCN2013071676-appb-I000013
推挽半桥传感器 55
Figure PCTCN2013071676-appb-I000014
Figure PCTCN2013071676-appb-I000015
参考半桥传感器 56
Figure PCTCN2013071676-appb-I000016
Figure PCTCN2013071676-appb-I000017
半推挽全桥传感器 57
Figure PCTCN2013071676-appb-I000018
Figure PCTCN2013071676-appb-I000019
半参考全桥传感器 58
Figure PCTCN2013071676-appb-I000020
Figure PCTCN2013071676-appb-I000021
表 1
如附图 7 所示，参考全桥传感器 51 中感应臂为 52 、 52' ，参考臂为 53 、 53' 。参考臂 53 上没有箭头，表示其 R-Hsense 曲线的斜率非常小。
如附图 6 所示，推挽全桥传感器 50 具有两类感应臂（ 52 、 52' ）以及（ 54 、 54' ），这两类感应臂的 R-Hsense 曲线的斜率是相反的。位于感应臂 52 和 54 上方的箭头是各自的 R-Hsense 曲线的斜率的符号。
由表 1 中第一行和第二行对比可以看出，推挽全桥传感器 50 相比参考全桥传感器 51 具有更大的灵敏度，因为所有的桥臂对信号都有贡献。
如附图 8 所示，推挽半桥传感器 55 有两个非对称的感应臂 52 、 54 ，
如附图 9 所示，参考半桥传感器 56 只有一个感应臂 52 和一个参考臂 53 。
如附图 10 所示，半推挽全桥传感器 57 有两个非对称的感应臂 52 、 54 以及两个驱动源 59 ，半推挽全桥磁场传感器由驱动源 59 驱动，而不是偏置电压。
如附图 11 所示，半参考全桥传感器 58 有一个感应臂 52 、一个参考臂 53 ，以及两个驱动源 59 ，半参考磁场传感器由驱动源 59 驱动，而不是偏置电压。
如附图 6 和 7 所示，推挽全桥传感器 50 和参考全桥传感器 51 的焊盘沿顺时针方向，从顶部开始依次为：偏置电压（ Vbias ）、右桥臂的中心点（ V2 ）、接地点（ GND ）以及左桥臂的中心点（ V1 ）。这四个桥式电路的外接焊盘都可以连接两个不同的电阻臂。通常通过电压表连接 V1 点和 V2 点测出其差值（ V1-V2 ）来测量桥式电路输出电压。
如附图 8 和附图 9 所示的推挽半桥电路传感器 55 和参考半桥传感器 56 具有 3 个外接焊盘，沿顺时针方向，从顶部开始依次为：偏置电压（ Vbias ）、中心点 V1 以及接地点（ GND ），桥式电路可通过此进行电连。
推挽半桥传感器 55 和参考电桥传感器 56 的输出电压可以通过很多已知的方法进行测量。一种方法是：在 V1 和 GND 的焊盘之间连接电压表， V1 和 GND 之间的电位差（ V1-GND ）就是输出电压。另一种方法是：在 V1 和 Vref （由外接电路或设备提供的稳恒电压）的焊盘之间连接电压表， V1 和 Vref 之间的电位差（ V1-Vref ）就是输出信号。 Vref 可由一个反向偏置的二极管、一个分压电路或其他已知的方法提供。
如附图 10 和附图 11 所示的半推挽全桥磁场传感器 57 和半参考全桥传感器 58 具有 3 个外接焊盘，沿顺时针方向，从顶部开始依次为：左半桥和右半桥。左半桥由恒流源 I1 （ 59 ），中心点 V1 以及接地点 GND 组成。右半桥由恒流源 I2 （ 59' ），中心点 V2 以及接地点 GND 组成。
半推挽全桥传感器 57 和半参考全桥传感器 58 的输出电压可以通过很多已知的方法进行测量。一种方法是：通过电压表连接 V1 点和 V2 点，测出其差值（ V1-V2 ）来测量桥式电路输出电压。
半推挽全桥传感器 57 和半参考全桥传感器 58 中的稳恒电流源 I1 和 I2 可以由许多已知的方法实现。一种方法是由电压控制反馈回路进行监控和调节一组磁电阻元件中单个磁电阻元件产生的电压，另一种方法是利用一组磁电阻元件中的一个磁电阻元件的输出。这种方法需要满足一组磁电阻元件的阻值远大于单个磁电阻元件的阻值。当电路工作时，桥式电路的阻值发生变化，桥式电路的电压也会相应发生变化，因为电路的能量由稳恒电流源提供，而不是电压源。
在参考全桥传感器 52 、参考半桥传感器 56 和半参考全桥传感器 58 中提到了'参考臂 53 '。所谓参考臂 53 是相对于感应臂来说具有很低的灵敏度，在响应曲线上表现为在传感器的工作范围内，感应臂的响应曲线的斜率的绝对值要远大于参考臂 53 。改变参考元件和传感元件的Δ R/R 是不实际的，因此可以通过改变 Hs 来改变灵敏度。这种方法可以通过几种不同技术的结合来实现：
磁屏蔽--将高磁导率铁磁层沉积在参考臂上以削弱外加磁场的作用。
形状各向异性能--由于参考元件和感应元件有不同的尺寸，因此具有不同的形状各向异性能。最普遍的做法是使参考元件的长轴长度大于感应元件的长轴长度，短轴长度小于感应元件的短轴长度，这样参考元件平行于敏感方向的退磁效应要远大于感应元件。
交换偏置--该技术是通过 MTJ 磁电阻元件自由层和相邻的反铁磁层或永磁层的交换耦合来构造一个有效的垂直于敏感方向的外场。可以在自由层和交换偏置层间设置 Cu 或 Ta 的隔离层来降低交换偏置强度。多层膜结构分述如下：
种子层 / 反铁磁层 1/ 铁磁层 /Ru/ 铁磁层 / 绝缘层 / 铁磁层 / 隔离层 / 反铁磁层 2/ 保护层 . . .
种子层 / 反铁磁层 1/ 铁磁层 Ru/ 铁磁层 / 绝缘层 / 铁磁层 / 隔离层 / 永磁层 / 保护层 . . .
种子层 / 反铁磁层 1/ 铁磁层 /Ru/ 铁磁层 / 绝缘层 / 铁磁层 / 反铁磁层 2/ 保护层 . . .
种子层 / 反铁磁层 1/ 铁磁层 /Ru/ 铁磁层 / 绝缘层 / 铁磁层 / 永磁层 / 保护层 . . .
其中，反铁磁层 1 （ AF1 ）和反铁磁层 2 （ AF2 ）是反铁磁材料，如 PtMn 、 IrMn 、 FeMn 。铁磁层（ FM ）采用一些具有代表性的由铁磁合金构成的铁磁薄膜或多层膜，包括但不限于 NiFe 、 CoFeB 、 CoFe 和 NiFeCo 。绝缘层可能是任何能够自旋极化的绝缘材料，如氧化铝或氧化镁。隔离层通常是 Ta 、 Ru 或 Cu 这些非铁磁材料构成的薄膜。反铁磁层 AF1 的反铁磁阻隔温度（ Blocking Temperature ）要低于 AF2 的，使铁磁层 /Ru/ 铁磁层结构的钉扎层的偏置场和自由层的偏置场正交垂直。
散场偏置（永磁偏置）--在该项技术中， Fe 、 Co 、 Cr 和 Pt 等永磁合金材料被沉积到传感元件表面或磁隧道结上，用于提供散磁场以偏置 MTJ 元件的响应曲线。永磁偏置的一个优势是可以在电桥构成以后，使用一个大的磁场来初始化永磁体。另外一个非常重要的优势是偏置场可以消除 MTJ 元件的磁畴，来稳定和线性化 MTJ 元件的输出。该设计的巨大优点在于其在设计调整上具有很大的灵活性。下面是可以实现的多层膜结构：
种子层 / 反铁磁层 1/ 铁磁层 /Ru/ 铁磁层 / 绝缘层 / 反铁磁层 / 厚隔离层 / 永磁层 / 保护层 . . .
其他技术涉及到在 MTJ 元件两侧设置偏置磁体。
以上调整灵敏度的技术可以单独使用或将几种技术结合起来使用。当将这些可用的几种技术结合起来可以使
Figure PCTCN2013071676-appb-I000022
极高，从而减少桥式传感器参考臂的 SMTJ ，提供一个非常稳定的的参考臂。
接下来将会对提供 Hcross 场的首选方式做一定描述。如附图 13 所示，磁电阻传感器 70 固定在两个片上永磁体 71 中间。半导体基片底部上构造的顶层显示的并不清晰。
条形永磁体之间具有间隙（ Gap ） 72 ，宽度（ W ） 73 ，厚度（ t ） 74 和长度（ Ly ） 75 。条形永磁体被设计为提供一个垂直于敏感轴（ Y 轴） 76 的交叉偏置场，主要是在基片的面内。这个轴被称为交叉轴或直接称为 X 轴 78 。磁电阻元件 70 被设计成具有宽度 WMR82 、长度 LMR83 的椭圆形状。穿过磁电阻元件 70 的部分见图 1 。
条形永磁体通常在初始阶段采用一个大的磁场充磁，因此它们的剩磁 MPM77 主要是垂直于敏感轴 76 的，在很大程度上是平行于 X 轴 78 的场，并位于 X-Y 面内。此处 X 轴和 Y 轴是标准正交的笛卡尔坐标轴， Z 轴是基片的法线方向。图 14 是磁感线在 X-Z 平面的投影。这些场的大小和方向是可以计算的。
条形永磁体的磁场被认为是在如图 15 所示的磁体的边缘 90 和 91 形成的虚拟磁荷和磁化边界条件作用的结果。剩磁 MPM77 的方向相对于敏感轴（ Y 轴） 76 呈夹角θ PM 92 。磁荷大小随着剩磁 MPM77 的大小和方向θ PM 92 进行变化，并且与条形永磁体的倾斜角（'θ ref '或'θ sns '）相关：
Figure PCTCN2013071676-appb-I000023
或
Figure PCTCN2013071676-appb-I000024
, (16)
虚拟磁荷产生的磁场为：
Figure PCTCN2013071676-appb-I000025
, (17)
如图 15 所示，在两块条形永磁体 71 间磁电阻元件 70 的面上的最终的磁场为矢量 Hgap94 。该场的分量方向主要垂直于条形永磁体 71 的边缘。场 94' 被复制平移到图的右侧以作比较。矢量 Hgap 和 X 轴之间的夹角θ gap 满足：
Figure PCTCN2013071676-appb-I000026
或
Figure PCTCN2013071676-appb-I000027
, (18)
在这种情况下θ PM = θ ref 或θ ref = π /2 ，位于磁电阻元件中心的磁场是剩磁 Mr 的函数：
Figure PCTCN2013071676-appb-I000028
, (19)
公式 19 是图 16 所示的 W73 和 gap72 的函数，该函数表示参考元件和感应元件的饱和场，可以通过改变磁体 71 的形状维度而改变。使用相同的 MTJ 元件、 MTJ 三维尺寸以及条形永磁体薄膜在参考元件和传感元件上，在 Hcross100 是 Hsense101 的 6.5 倍作用下，参考元件的饱和场是传感元件的 6.5 倍。这个比值对于带有参考臂 53 电桥来说是足够的，而通过适当的设计可以将这个比值增加到 10 。对于图 6 中的推挽全桥传感器 50 只设置了一种条形永磁体薄膜尺寸，因为这种结构并没有参考臂，所以不需要。
图 17 是图 16 中的磁电阻元件周围的磁场分量示意图。包括 Hcross95 、 Hoff96 以及其合矢量 Hgap94' 。该图表明通过设置条形永磁体 71 边缘和敏感方向的夹角，可以同时产生 Hcross95 和消除偏移场 Hoff96 ，这是为了： (1) 设定磁电阻元件 70 的饱和场值，消除其偏移场 HO23 ； (2) 优化电桥输出的对称性、偏移和灵敏度。此外，设置剩磁 MPM77 和敏感方向的夹角θ PM 92 是为了在传感芯片制备以后，可以提供一个微调装置能够最小化偏移值或对称性，这种方法可以提高产品优率。
完成对基片上条形永磁体产生的交叉轴磁场的大致描述之后，现在对方程 (8) 求导推出方程 (9) ，该方程表明了磁电阻灵敏度与其几何形状项以及铁磁材料的性能的关系。这一理论的发展是 MTJ 元件的自由层 6 的磁性物质具有厚度 TMR11 （见图 1 ）。磁电阻元件 70 自由层在 X-Y 平面的形状如图 8 和图 11 所示，磁电阻元件 70 具有长轴 LMR83 比短轴 WMR82 长的椭圆形轮廓，长轴和短轴分别和 Y 轴 76 、 X 轴 78 平行。
当磁电阻元件工作时，它受到如图 15 所示的净矢量场 HMR104 的作用，外场和 X 轴具有夹角θ MR 105 ，这样可以产生磁电阻元件 70 自由层 6 的净磁能 MMR106 。 MMR106 相对于 X 轴具有夹角Φ MR 107 。
灵敏度被定义为 R-Hsense 曲线在场强为零时的一阶导数（斜率），可以通过下面的方法进行计算：
(1) 找到磁电阻元件的磁自由能关于 HMR 、 MMR 的函数， HMR 、 MMR 关于θ MR 和Φ MR 的函数；
(2) 使能级最小化；
(3) 解决角度θ MR 和外场的函数关系；
(4) 得到 MMR-HMR 函数的导数在 HMR=0 时的值已决定零场时的灵敏度。
为了解释磁电阻元件的尺寸对其磁性能的影响，给出典型的 LMR 、 WMR 以及 TMR 值，分别为 3000 nm 、 12000 nm 以及 6 nm ，其在 X 、 Y 、 Z 方向上的比例为 500:2000:1 。因此，在这个尺寸下的退磁因子为：
Figure PCTCN2013071676-appb-I000029
, (20)
总能量 = 外场赋加的能量 + 自身的能量
Figure PCTCN2013071676-appb-I000030
, (21)
第二项的自发磁化场包括两个在 X 、 Y 、 Z 具有常量的单轴场：一个是退磁场 (d) ，另一个是材料各向异性能 (k) 。
Figure PCTCN2013071676-appb-I000031
, (22)
Figure PCTCN2013071676-appb-I000032
, (23)
Figure PCTCN2013071676-appb-I000033
, (24)
然后做一些简化近似：
(1) HMR 完全沿着 Y 轴；
(2) Hcross 完全沿着 X 轴；
(3) Mz=0 ，因为 dz >> dx, dy 。
则方程 (21) 简化为：
Figure PCTCN2013071676-appb-I000034
, (25)
将 (22) 和 (23) ***至 (25) ，则总能量变为：
Figure PCTCN2013071676-appb-I000035
, (26)
Figure PCTCN2013071676-appb-I000036
, (27)
Figure PCTCN2013071676-appb-I000037
, (28)
将 (28) 最小化以找到方程对θ的依赖：
Figure PCTCN2013071676-appb-I000038
, (29)
假设 Hcross 使磁电阻元件的 MMR 饱和，因此我们可以解决极小角θ的极限：
Figure PCTCN2013071676-appb-I000039
, (30)
Figure PCTCN2013071676-appb-I000040
, (31)
注意，总的各向异性能为：
Figure PCTCN2013071676-appb-I000041
, (32)
使用极小角度的近似：
Figure PCTCN2013071676-appb-I000042
, (33)
零场的一阶导数为：
Figure PCTCN2013071676-appb-I000043
, (34)
假设电桥传感器在饱和状态下的电压为 Vp ，则灵敏度为：
Figure PCTCN2013071676-appb-I000044
, (35)
这与交叉场 Hcross 和各向异性场 Hk 的差异相关。图 18 是灵敏度（ V/V/Oe ）随 Hcross/Hk （无量纲）变化的曲线。可以看到随着 Hcross/Hk 的减小至 1 ，灵敏度的计算值增值无穷大。实际上， Hcross 设置为稍微比 Hk 要高，这样就可以使传感器的感应区域更宽，同时降低磁滞，避免其他的磁场影响，使自由层的 MMR 不至于被饱和。
在大规模工业生产中，磁电阻元件是制备在圆形的基片上，称之为晶圆，在具体应用中可将晶圆切割为单个或两个磁电阻元件的芯片进行电连构成电桥，再进行封装。
图 19 是使用如图 16 和图 13 中的磁电阻元件 70 的推挽全桥传感器芯片的布局图。两个相同的芯片 122 和 123 是由同一块晶圆切割制成，被封装为一个传感器。两块芯片相对于 Z 轴相互旋转 180 °，其敏感面为 X-Y 平面。每一个芯片都有两个电隔离的磁电阻感应臂。
推挽全桥传感器 50 通过引线 125 进行电连接。矩形的焊盘位于每个芯片的边缘，除了一个焊线位是圆形的，以便于直观地确定每一个芯片焊盘的数量和方向。每一个电路的节点都有两个焊盘（总共有 8 个），一个用于内部的桥式连接，另一个用于与外部的器件连接。这使得位于芯片 122 顶部的焊盘可以通过引线连接到引线框的封装引脚和 PCB 上。
在所给的芯片中，元件的长轴沿着敏感轴方向。芯片上的条形永磁体呈倾斜设置，具有宽度 W73 ，两块磁体间的间距为 Gap72 ，倾斜角为θ sns 93 。这些磁体提供了磁偏置场，来饱和感应元件，当附加提供的 Hoff 满足 Hoff-Ho > Hsat 时（这是一个推挽桥展示其线性工作状态所必须的），右上方的负的磁电阻 54' 连接于 GND 和 V2 之间，左上方负的磁电阻 54 连接在 Vbias 和 V1 之间。磁电阻 54 和 54' 的 R-Hsense 响应曲线见中插图 120 ，在外场 Hsense 的负方向具有高阻态。
图 20 是参考全桥传感器 51 的布局图，该参考全桥设置了感应臂和参考臂间具有不同宽度、角度以及间隔的倾斜的条形永磁体 . 如图 20 所示，构成参考臂的磁电阻元件的长轴垂直于敏感轴 Y 轴，在 X 轴方向上的长度要大于构成感应臂的磁电阻元件在 X 轴方向上的长度，使参考臂平行于敏感方向的退磁效应要远大于感应臂。在这个设计中，参考臂和感应臂在基片上一次性制备完成，可通过在基片上沉积导线或引线键合进行电连接构成电桥结构，从该晶圆上切割制成的参考全桥传感器位于一个基片上，这种结构我们称之为'单片式传感器'，单片式传感器相对于多芯片封装的传感器来说，简化了制备工艺的同时缩小了传感器的体积。 MTJ 元件串位于不同倾角的条形永磁体的中间， 115 、 116 、 117 和 118 为电桥的桥臂。在这个设计中，θ ref = π /2 ，θ sns 在π /4 和π /2 之间。使偏移归零的优化的同时可以调整参考臂和感应臂上 MTJ 元件的数量，或只是对参考臂或感应臂偏移优化。如图虚线所示的矩形屏蔽层 119 也是可选的方法。屏蔽层的作用是进一步降低参考臂 115 和 116 的有效灵敏度。
其余桥式磁场传感器的布局图与上述相似，在此就不再累述了。
用于测量磁场的磁电阻传感器能够实现大规模生产，测量磁场的灵敏度更高，同时具备功耗低、尺寸小的特点。
上述实施例只为说明本发明的技术构思及特点，其目的在于让熟悉此项技术的人士能够了解本发明的内容并据以实施，并不能以此限制本发明的保护范围。凡根据本发明精神实质所作的等效变化或修饰，都应涵盖在本发明的保护范围之内。

Claims (42)

1. 一种用于测量磁场的磁电阻传感器，其特征在于：它包括：
基片，所述基片具有一' X-Y '表面，所述磁电阻传感器的敏感轴平行于 Y 轴， X 轴垂直于 Y 轴；
至少一个感应臂，所述感应臂由磁电阻元件构成，所述磁电阻元件设置在基片的' X-Y '表面上，所述磁电阻元件沿 Y 轴方向的长度大于其沿 X 轴方向的长度；
多个设置在所述基片上的条形永磁体，相邻两个条形永磁体之间形成间隙磁场，该间隙磁场具有沿 X 轴和 Y 轴的分量；
焊盘，所述焊盘设置在感应臂的末端，可以通过其将感应臂相电连。
2. 如权利要求 1 所述的磁电阻传感器，其特征在于：至少一个所述磁电阻元件被所述间隙磁场在 X 轴方向饱和。
3. 如权利要求 1 所述的磁电阻传感器，其特征在于：所述磁电阻传感器的磁电阻阻值随外场变化的响应曲线在所述磁电阻传感器的工作区间内具有高线性度、高斜率值、低磁滞。
4. 如权利要求 1 所述的磁电阻传感器，其特征在于：对条形永磁体充磁来调节该条形永磁体的磁化强度和方向，以调节磁电阻传感器的输出性能。
5. 如权利要求 1 所述的磁电阻传感器，其特征在于：磁电阻元件为 MTJ 元件或 GMR 元件。
6. 如权利要求 1 所述的磁电阻传感器，其特征在于：所述磁电阻传感器为桥式磁场传感器。
7. 如权利要求 6 所述的磁电阻传感器，其特征在于：所述桥式磁场传感器为推挽全桥磁场传感器。
8. 如权利要求 7 所述的磁电阻传感器，其特征在于：所述推挽全桥磁场传感器包括四个感应臂，在所述磁电阻传感器的工作区间内，其中两个感应臂的磁电阻阻值随外场变化的响应曲线相对另外两个感应臂的磁电阻阻值随外场变化的响应曲线在相同的外场作用下具有相反的变化趋势。
9. 如权利要求 8 所述的磁电阻传感器，其特征在于：所述推挽全桥磁场传感器包括两个传感器芯片，每个传感器芯片包括具有' X-Y '表面的基片和设置在基片表面上的两个感应臂，其中一个传感器芯片相对另一个传感器芯片以旋转 180 度 的方式 排布，两个传感器芯片由同一晶圆切割制成。
10. 如权利要求 9 所述的磁电阻传感器，其特征在于：所述感应臂之间能够通过引线连接焊盘实现电连。
11. 如权利要求 6 所述的磁电阻传感器，其特征在于：所述桥式磁场传感器为参考全桥磁场传感器，该参考全桥磁场传感器包括感应臂和参考臂，每个参考臂由磁电阻元件构成。
12. 如权利要求 11 所述的磁电阻传感器，其特征在于：所述参考全桥磁场传感器包括两个感应臂和两个参考臂，在所述磁电阻传感器的工作区间内，感应臂的磁电阻阻值随外场变化的响应曲线的斜率绝对值远大于参考臂的磁电阻阻值随外场变化的响应曲线的斜率绝对值。
13. 如权利要求 12 所述的磁电阻传感器，其特征在于：所述参考全桥磁场传感器包括一个传感器芯片，该传感器芯片包括具有' X-Y '表面的基片和设置在基片表面上的构成感应臂的磁电阻元件和构成参考臂的磁电阻元件。
14. 如权利要求 13 所述的磁电阻传感器，其特征在于：构成所述参考臂的磁电阻元件沿 X 轴方向的长度大于其沿 Y 轴方向的长度，且其沿 X 轴方向的长度大于构成所述感应臂的磁电阻元件沿 X 轴方向的长度。
15. 如权利要求 13 所述的磁电阻传感器，其特征在于：构成所述参考臂的磁电阻元件的表面覆盖有一层高磁导率的铁磁屏蔽层。
16. 如权利要求 13 所述的磁电阻传感器，其特征在于：设置在参考臂附近的条形永磁体在 X 轴方向的磁场分量大于设置在传感臂附近的条形永磁体在 X 轴方向的磁场分量。
17. 如权利要求 13 所述的磁电阻传感器，其特征在于：构成参考臂或感应臂的磁电阻元件上设置有一层膜或多层膜构成的永磁偏置层。
18. 如权利要求 13 所述的磁电阻传感器，其特征在于：构成参考臂的磁电阻元件上设置有一层膜或多层膜构成的交换偏置层。
19. 如权利要求 6 所述的磁电阻传感器，其特征在于：所述桥式磁场传感器为推挽半桥磁场传感器，该推挽半桥磁场传感器由两个感应臂构成。
20. 如权利要求 19 所述的磁电阻传感器，其特征在于：所述推挽半桥磁场传感器包括两个感应臂，在所述磁电阻传感器的工作区间内，其中一个感应臂的磁电阻阻值随外场变化的响应曲线相对另一个感应臂的磁电阻阻值随外场变化的的响应曲线在相同的外场作用下具有相反的变化趋势。
21. 如权利要求 20 所述的磁电阻传感器，其特征在于：所述推挽半桥磁场传感器包括两个传感器芯片，每个传感器芯片包括具有' X-Y '表面的基片和设置在基片表面上的感应臂，其中一个传感器芯片相对另一个传感器芯片以旋转 180 度 的方式 排布，两个传感器芯片由同一晶圆切割制成。
22. 如权利要求 21 所述的磁电阻传感器，其特征在于：所述推挽半桥磁场传感器的感应臂之间能够通过引线连接焊盘实现电连。
23. 如权利要求 6 所述的磁电阻传感器，其特征在于：所述磁电阻传感器为参考半桥磁场传感器，该参考半桥磁场传感器包括感应臂和参考臂，每个参考臂由磁电阻元件构成。
24. 如权利要求 23 所述的磁电阻传感器，其特征在于：所述参考半桥磁场传感器包括一个感应臂和一个参考臂，在所述磁电阻传感器的工作区间内，感应臂的磁电阻阻值随外场变化的响应曲线的斜率绝对值远大于参考臂的磁电阻阻值随外场变化的响应曲线的斜率绝对值。
25. 如权利要求 24 所述的磁电阻传感器，其特征在于：所述参考半桥磁场传感器包括一个传感器芯片，该传感器芯片包括具有' X-Y '表面的基片和设置在基片表面上的构成感应臂的磁电阻元件和构成参考臂的磁电阻元件。
26. 如权利要求 25 所述的磁电阻传感器，其特征在于：构成所述参考臂的磁电阻元件沿 X 轴方向的长度大于其沿 Y 轴方向的长度，且其沿 X 轴方向的长度大于构成所述感应臂的磁电阻元件沿 X 轴方向的长度。
27. 如权利要求 25 所述的磁电阻传感器，其特征在于：构成所述参考臂的磁电阻元件的表面覆盖有一层高磁导率的铁磁屏蔽层。
28. 如权利要求 25 所述的磁电阻传感器，其特征在于：设置在参考臂附近的条形永磁体在 X 轴方向的磁场分量大于设置在传感臂附近的条形永磁体在 X 轴方向的磁场分量。
29. 如权利要求 25 所述的磁电阻传感器，其特征在于：构成参考臂或感应臂的磁电阻元件上设置有一层膜或多层膜构成的永磁偏置层。
30. 如权利要求 25 所述的磁电阻传感器，其特征在于：构成参考臂的磁电阻元件上设置有一层膜或多层膜构成的交换偏置层。
31. 如权利要求 6 所述的磁电阻传感器，其特征在于：所述磁电阻传感器为由两个独立的电流驱动源和两个感应臂全桥连接构成的半推挽全桥磁场传感器。
32. 如权利要求 31 的磁电阻传感器，其特征在于：所述半推挽全桥磁场传感器中的一个感应臂的磁电阻阻值随外场变化的响应曲线相对另一个感应臂的磁电阻阻值随外场变化的响应曲线在相同的外场具有相反的变化趋势。
33. 如权利要求 32 的磁电阻传感器，其特征在于：所述半推挽全桥磁场传感器包括两个传感器芯片，每个传感器芯片包括具有' X-Y '表面的基片和设置在基片表面上的感应臂，其中一个传感器芯片相对另一个传感器芯片以旋转 180 度 的方式 排布，两个传感器芯片由同一晶圆切割制成。
34. 如权利要求 33 的磁电阻传感器，其特征在于：所述半推挽全桥磁场传感器的感应臂之间能够通过引线连接焊盘实现电连。
35. 如权利要求 6 所述的磁电阻传感器，其特征在于：所述磁电阻传感器为由两个独立的电流驱动源、一个感应臂和一个参考臂全桥连接构成的半参考全桥磁场传感器。
36. 如权利要求 35 所述的磁电阻传感器，其特征在于：所述感应臂的磁电阻阻值随外场变化的响应曲线的斜率绝对值远大于参考臂的磁电阻阻值随外场变化的响应曲线的斜率绝对值。
37. 如权利要求 36 所述的的磁电阻传感器，其特征在于：所述半参考全桥磁场传感器包括一个传感器芯片，该传感器芯片包括具有' X-Y '表面的基片和设置在基片表面上的构成感应臂的磁电阻元件和构成参考臂的磁电阻元件。
38. 如权利要求 37 所述的磁电阻传感器，其特征在于：构成所述参考臂的磁电阻元件沿 X 轴方向的长度大于其沿 Y 轴方向的长度，且其沿 X 轴方向的长度大于构成感应臂的磁电阻元件沿 X 轴方向的长度。
39. 如权利要求 37 所述的磁电阻传感器，其特征在于：构成所述参考臂的磁电阻元件的表面覆盖有一层高磁导率的铁磁屏蔽层。
40. 如权利要求 37 所述的磁电阻传感器，其特征在于：设置在参考臂附近的条形永磁体在 X 轴方向的磁场分量大于设置在传感臂附近的条形永磁体在 X 轴方向的磁场分量。
41. 如权利要求 37 所述的磁电阻传感器，其特征在于：构成参考臂或感应臂的磁电阻元件上设置有一层膜或多层膜构成的永磁偏置层。
42. 如权利要求 37 所述的磁电阻传感器，其特征在于：构成参考臂的磁电阻元件上设置有一层膜或多层膜构成的交换偏置层。
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