HK1095376B - Sensing apparatus including integrated set/reset driver and magneto-resistive sensor - Google Patents

Description

Sensing device comprising an integrated set/reset driver and a magneto-resistive sensor

RELATED APPLICATIONS

This application claims the benefit of the following U.S. provisional applications: (1) 60/475175, filed On 2.6.2003, having a Honeywell case number of H0004956 entitled "On-Die Set/Reset Driver for a magnetic-Resistive Sensor" (Set/Reset Driver On Die for magnetoresistive Sensor), inventor Mark D.Amundson and William F.Witcaft; (2) 60/475191 filed on 2.6.2003 under the name "semiconductor device integrated with magnetoresistive Sensor with a magnetic-Resistive-sensing Sensor" (semiconductor device) with a Honeywell case number of H0004602, inventor: Lonny L.berg and William F.Witcraft; and (3) 60/462872, filed on 15.4.2003 under the name of Honeywell case number H0004948 entitled "Integrated GPS Receiver and magneto-Resistive Sensor Device", to William F.Witcaft, Hong Wan, Cheisan J.Y., and Tamara K.Bratland. The entire contents of each of these provisional applications are also incorporated herein by reference.

This application is also related to and incorporated by reference into the following U.S. non-provisional applications: (1) the invention is also filed, the Honeywell case number is H0004602US, the invention name is 'Semiconductor Device Integration with a magnetic-ResistentSensor', the invention is Lonny L.berg and William F.Witcaft; and (2) ___ filed concurrently with the same, having the Honeywell case number H0004948US entitled "Integrated GPS Receiver and magnetic-reactive Sensor Device", by William F.Witcaft, Hong Wan, Cheisan J.Yue, and TamaraK.Bratland.

Technical Field

The present invention relates generally to magnetic field and current sensors, and more particularly, but not by way of limitation, to signal processing for magnetoresistive sensors.

Background

Magnetic field sensors are used for magnetic compasses, ferrous metal detection and current sensing. They can detect magnetic field changes in machine components, earth's magnetic field, underground mines, or electrical devices and lines.

In magnetic sensors, particularly Anisotropic Magnetoresistive (AMR) bridge sensors, a thin film of magnetoresistive material is deposited on a silicon substrate to accurately sense the strength and/or direction of a local magnetic field. Since the deposition of thin films on silicon substrates may utilize semiconductor foundry (semiconductor foundry) processes for fabrication, additional steps may be added to create adjacent semiconductor circuit elements. These semiconductor circuit elements are not typically co-located on the same substrate as the magnetoresistive sensor because the sensor film is not compatible with conventional semiconductor manufacturing processes.

Typically, magnetoresistive sensors use Permalloy (Permalloy), which is a ferromagnetic alloy containing nickel and iron, as the magnetoresistive material. Typically, the permalloy is disposed in thin strips of permalloy film. When a current is passed through a single strip, the direction of magnetization of the strip may form an angle with the direction of current flow. When the direction of magnetization changes, the effective resistance of the strip changes. In particular, a magnetization direction parallel to the direction of the current flow results in the greatest resistance through the strip, and a magnetization direction perpendicular to the direction of the current flow results in the least resistance through the strip. This changing resistance may cause the voltage drop across the strip to change as current passes through the strip. This change in voltage can be measured as an indication of a change in the direction of magnetization of the external magnetic field acting on the strip.

To form the magnetic field sensing structure of a magnetoresistive sensor, several strips of permalloy may be electrically connected together. The permalloy strips may be placed on the substrate of the magnetoresistive sensor as continuous resistors of the "herringbone" type or as linear strips of magnetoresistive material with the conductors across the strips at a 45 degree angle to the long axis of the strips. The latter configuration is known as "barberpole biasing". Because of the configuration of these conductors, the current in the strip can be forced to flow at a 45 degree angle to the long axis of the strip. These sensing structure designs are described in detail in U.S. patent No. 4847584 issued to Bharat b.pant on 11/7/1989 and assigned to the assignee of the present application. The entire contents of U.S. patent No. 4847584 are hereby incorporated by reference. Other patents and patent applications describing magnetic sensor technology are set forth below in conjunction with the description of FIG. 2.

Magnetic sensors typically include multiple reorientation elements or "strips" through which current can pass for controlling and adjusting these sensing characteristics. For example, magnetic sensor designs often include a set/reset and/or offset reorienting element or "tape" (hereinafter referred to as "set/reset tape" and "offset tape").

The offset band is used to cancel or modify the external magnetic field. The set/reset strap helps reorient the magnetoresistive thin-film texture for optimal measurement accuracy. This process of reorienting the magnetoresistive film uses the set/reset strap metallization to apply a short (brief) high magnetic field strength to force the randomly oriented film texture substantially in one direction. The application of such a short field (brief field) places the film "on" in one orientation. A second short field application of similar strength but opposite orientation "resets" the film's grain orientation. A magnetic field that is repeatedly set and/or reset is used to ensure that the thin film particles remain undisturbed and in a relatively known magnetic orientation.

Although the set/reset straps themselves are typically on-chip, the driver circuitry for these straps is typically not on-chip, making space inefficient. Such off-chip solutions typically pulse the current through one or more strips (typically metal) on the magnetoresistive sensor bridge, but use external board level circuitry to switch and generate the current pulse.

Similarly, other components, such as operational amplifiers, transistors, capacitors, and the like, are typically implemented on a separate chip from the magnetoresistive sensor. For example, signal conditioning and electrostatic discharge circuitry is typically not on-chip. While this may be good for some applications, for other applications where physical space is at a premium, it would be desirable to have one or more of the semiconductor components be part of the same chip as the magnetoresistive sensor. Therefore, a single chip design, and in particular a design with set/reset driver circuits located on the chip, would be desirable.

Disclosure of Invention

A magnetic sensing device and methods of making and using the same are disclosed. The sensing device may include one or more magneto-resistive-sensing elements for detecting or measuring a magnetic field, one or more reorientation elements for adjusting the magneto-resistive-sensing elements, and a semiconductor circuit having a driver circuit for controlling or driving the reorientation elements. The magneto-resistive-sensing element, the reorientation element, and the semiconductor circuit may all be arranged in a single package and/or monolithically formed on a single chip. Alternatively, the semiconductor circuit and the at least one magneto-resistive-sensing element are monolithically formed on a single chip; the semiconductor circuit, the at least one reorientation element and the at least one magneto-resistive-sensing element are monolithically formed on a single chip; or at least a portion of the semiconductor circuit is monolithically formed on the first chip with the at least one magneto-resistive-sensing element and the at least one reorientation element. At least a portion of the semiconductor circuit is formed on the second chip. Alternatively, the first and second chips are electrically connected together. Alternatively, the first chip is placed orthogonally to the second chip. Alternatively, the second chip is placed close to the first chip. Alternatively, the first and second chips do not have electrical connections, wherein any electrical interaction is independent of the electrical connections.

Drawings

Preferred embodiments of the present invention will now be described in conjunction with the following drawing figures, wherein like numerals denote like elements throughout the several views, and wherein:

FIG. 1 is a simplified block diagram illustrating the integration of one or more semiconductor device components with a magnetoresistive sensor in accordance with an exemplary embodiment;

FIG. 2 is a block diagram depicting a magnetoresistive sensor with integrated set/reset driver circuitry according to an exemplary embodiment;

FIG. 3 is a schematic diagram illustrating a set/reset circuit with a magnetoresistive sensor that may be implemented on-die (on-die) in accordance with an exemplary embodiment;

FIG. 4 is a plan view of a magnetoresistive sensor having a semiconductor component according to an exemplary embodiment;

FIG. 5 is a first simplified circuit diagram depicting a first compass circuit integrated with a magnetoresistive sensor in accordance with an exemplary embodiment; and

the second simplified circuit diagram of FIG. 6 depicts a second compass circuit integrated with a magnetoresistive sensor according to an exemplary embodiment.

Detailed Description

In view of the wide variety of embodiments to which the principles of the present invention may be applied, it should be understood that the described embodiments are exemplary only, and should not be taken as limiting the scope of the invention.

FIG. 1 is a simplified block diagram illustrating integration of one or more semiconductor device components with a magnetoresistive sensor, according to an embodiment. In general, the term integrated or integrated may mean that one or more subsystems are included in a larger system. On the other hand, integration may refer to the integration of the subsystem, its structure and functionality with other components of a larger system. Except where noted, the words integrated and integrated may be used interchangeably throughout this specification to describe a combination of components in accordance with either definition or both.

The device 100 includes first and second portions 102, 104. The first portion 102 may include magnetoresistive sensing elements (hereinafter collectively referred to as "MR sensors") and wiring, such as thin film traces. The second portion 104 may include one or more semiconductor device components, such as set/reset driver circuits. In a preferred embodiment, the second portion 104 also includes signal conditioning circuitry and circuitry for ESD (electrostatic discharge) protection of the MR sensor in the first portion 102. As described below, the second portion 104 may be processed in particular by standard semiconductor manufacturing techniques, such as those used for CMOS (complementary metal oxide semiconductor).

The first and second portions 102, 104 may be disposed on the same chip, making the device 100 a separate single chip or monolithically integrated design. Prior attempts to integrate semiconductor devices with MR sensors typically included at least two dies that were separately placed on a printed circuit board, which likely resulted in larger size and increased complexity for end-user devices (e.g., cell phones, portable devices, watches, automotive sensors, etc.). The single chip design of the apparatus 100 provides reduced size and increased functionality.

For example, the first and second portions 102, 104 may be fabricated using standard RF/microwave processing, such as using CMOS, Bipolar, BiCMOS, GaAs (gallium arsenide), and InP (indium phosphide). Although technologies such as GaAs may have advantages in terms of operational speed, reduced power consumption may best be achieved by using other technologies such as those including SOI (silicon on insulator) or MOI (microwave on insulator), SOI variants. In one embodiment SOI 0.35 μ processing is used.

In a preferred embodiment, the first portion 102 is fabricated using standard lithographic, metallization and etching processes, such as those described in the patent lists referenced below. However, other techniques for manufacturing MR sensors may also be used. Second portion 104 is preferably fabricated using SOI 0.35 μ process, or another RF/microwave process, such as GaAs process.

The MR sensor may be integrated with one or more semiconductor device components by one of at least two methods. In a first embodiment, the MR sensor may be fabricated on the same die as the semiconductor device assembly, and may include other circuitry, such as signal conditioning and ESD protection circuitry. In a second embodiment, the MR sensor is fabricated on a first die, while at least some of the semiconductor device components are fabricated on a second die.

The first and second dies may then be placed in close proximity to each other and may be packaged within a single integrated circuit chip. In either case, depending on the particular application, one or more connections may advantageously be included between the semiconductor device assembly and the MR sensor. For example, such a connection may provide feedback. Alternatively, the semiconductor device assembly and the MR sensor may simply be in physical proximity to each other without intentional electrical interaction.

Since conventional semiconductor processing techniques may be used, specific semiconductor device circuitry is not disclosed herein because it is relatively flexible. Thus, conventional semiconductor designs that may be implemented in CMOS/Bipolar/BiCMOS may be utilized in accordance with the presently disclosed embodiments. Example semiconductor devices that may be implemented include, but are not limited to, capacitors, inductors, operational amplifiers, set/reset circuitry for MR sensors, accelerometers, pressure sensors, position sensing circuitry, compass circuitry, and the like.

Certain semiconductor device components may generate electromagnetic fields that appear to be sufficient to affect the operation of the MR sensor. Thus, it may be desirable to physically separate the sensing components of the MR sensor portion 102 of the integrated device 100 from the components of the semiconductor device portion 104 to provide optimal sensing operation. The amount of separation may be determined, for example, using theoretical or empirical means. As an alternative to introducing physical isolation between potentially interfering components of the integrated device 100, a shielding layer may be provided, as described in U.S. provisional patent application No. 60/475191.

Demonstration of manufacturing techniques

Fig. 2 depicts an example cross-section of an apparatus 200 in which one or more semiconductor components, such as those used with set/reset driver circuits, may be implemented with an MR sensor. For the purposes of this example, assume that CMOS/Bipolar semiconductor technology is used. Semiconductor device components (including any signal conditioning circuitry and drivers for setup and/or offset strips associated with the MR sensor portion) can be fabricated in bulk in a CMOS/Bipolar underlayer, while the MR sensor can be fabricated in layer 202-206 above the contact glass layer 208. Also shown in FIG. 2 are various contacts V1-V3 and metallizations M1-M3, as well as the NiFe permalloy structure (see first dielectric layer 206). In addition to the bottom layer 210, the contact glass layer 208, and the first dielectric layer 206, a second dielectric layer 204 and a passivation layer 202 are also shown.

In one embodiment, layer 202 is formed using standard photolithography, metallization, and etch processes 206, while layer 208 is formed using an SOI 0.35 μ process, or using other RF/microwave methods, such as using a GaAs process 210. Other components of the MR sensor (such as the set, reset and offset straps; signal conditioning circuitry, and ESD protection circuitry) may be included at various locations in layers 206 and 210, and are not fully shown in FIG. 2.

Exemplary magnetoresistive design

For further information on the design of MR sensors, reference may be made to the following patents and/or patent applications to Honeywell, the entire contents of which are incorporated herein by reference.

(1) U.S. Pat. No. 6529114 to Bohlinger et al, "Magnetic field sensing Device"

The device comprises a two-axis integrated device for measuring a magnetic field, comprising two sensor cells formed of an MR material having a crystalline anisotropy field direction. The elements of the first of the two sensor cells have a full anisotropy field in a first direction. The elements of the second of the two sensor units have a full anisotropy field in a second direction perpendicular to the first direction. Means are provided for setting the magnetization direction in the elements of the first and second sensor units. The output of the first sensor unit represents the magnetic field component perpendicular to the first direction and the output of the second sensor unit represents the magnetic field component perpendicular to the second direction.

(2) U.S. Pat. No. 6232776 to Pant et al, "Magnetic Field Sensing for interferometric Sensing an inductive Magnetic Field in a sensor plane" ("Pant et al")

Pant et al provide a magnetic field sensor that anisotropically senses an incident magnetic field. This may preferably be done by providing a magnetic field sensor device having one or more ring-shaped MR sensor elements for sensing the incident magnetic field. The MR material used is preferably anisotropic and may be either colossal magneto-resistive (CMR) material or some form of giant magneto-resistive (GMR) material. Since the shape of the sensor element is annular, the shape anisotropy is minimized. The resulting output provided by the magnetic field sensor arrangement is then relatively independent of the direction of the incident magnetic field in the sensor plane.

In one embodiment of Pant et al, the magnetic field sensor includes a first leg and a second leg. The first pin is connected between the output network and a first power supply terminal. The second pin is connected between the output network and a second power supply terminal. In order to anisotropically sense an incident magnetic field, at least one ring-shaped sensor element formed of an MR material is included in at least one of the first and second legs. Preferably, two or more annular MR sensor elements are included in the first or second leg, and the other leg is formed of a non-magnetoresistive material. The two or more ring sensor elements are preferably connected in a series configuration by a plurality of non-magnetoresistive connectors to form respective legs.

In order to maximize the sensitivity of the magnetic sensor device, the ring-shaped sensor element is preferably formed of a CMR material. However, the use of GMR materials is also contemplated. Exemplary CMR materials are those MnO typically expressed by the formula (LnA)₃A material represented by wherein Ln ═ La, Nd, or Pr, and a ═ Ca, Sr, Ba, or Pb. Preferably, the colossal MR material is LaCaMnO, with a La concentration of between 26 and 32 atomic percent, a Ca concentration of between 9 and 20 atomic percent, and a Mn concentration of between 47 and 64 atomic percent.

In another embodiment of Pant et al, the magnetic field sensor includes a first leg, a second leg, a third leg, and a fourth leg. The first and second pins are preferably connected between the first and second output networks and the first power supply terminal, respectively. The third and fourth pins are preferably connected between the third and fourth output networks, respectively, and the first power supply. In order to anisotropically sense an incident magnetic field, at least one ring-shaped sensor element formed of an MR material is included in at least one of the first, second, third and fourth legs. Preferably, the first and fourth legs are each formed from two or more annular MR sensor elements, and the second and third legs are formed from non-magnetoresistive material. For each of the first and fourth legs, a corresponding two or more ring sensor elements are preferably connected in a series configuration by a plurality of non-magnetoresistive connectors to form a corresponding leg. The annular MR sensor element is preferably formed of the same CMR material as described above.

(3) U.S. Pat. No. 5952825 to Wan, "Magnetic Field sensing devices with inductive Coils for Producing Magnetic Fields" ("Wan")

Wan provides a set/reset feature and an independent feature of generating a known magnetic field at the magnetic sensing element by using a unique coil structure. The presence of these two features in the magnetic field sensor adds more sensor functions than the sum of the individual functions of the two features.

In order to simplify this, Wan uses extremely small low power devices comprising means for setting and resetting magnetic domains in MR sensors arranged in a bridge network, and current strips for setting the magnetization direction in the opposing bridge elements. The magnetization directions in the opposite bridge elements may be arranged in the same or opposite directions, depending on the particular design. The current strip generates a known magnetic field at the magnetic field sensing element. The known magnetic field is used for functions such as testing, setting, compensation and calibration, and feedback applications.

(4) U.S. Pat. No. 5820924 to Witcraft et al, "Method of simulating a magnetic Sensor"

Witcraft et al provides a method comprising: (i) manufacturing a magnetic field sensor comprising the steps of providing a silicon substrate; (ii) forming an insulating layer as a new line on a substrate generating a first magnetic field; (iii) forming a layer on the insulating layer in the presence of said first magnetic field of the MR material; (i v) determining a first value of the anisotropy field; and (v) annealing at a temperature selected to provide the desired anisotropy field.

(5) U.S. Pat. No. 5247278 to Pant et al, "Magnetic Field sensing device" ("Pant et al II")

Pant et al II provides a set/reset feature and a separate feature that generates a known magnetic field at the magnetic sensing element. The presence of these two features in the magnetic field sensor adds more sensor functions than the sum of the individual functions of the two features.

In one aspect, Pant et al II includes means for setting and resetting magnetic domains in MR sensing elements arranged in a bridge network. Current strips are provided for setting the magnetization direction in opposite bridge elements in the same direction or in opposite directions, depending on the specific design. In another aspect of the invention, the second current strap generates a known magnetic field at the magnetic field sensing element. The known magnetic field is used for functions such as testing, setting and calibration.

(6) Witcraft et al, U.S. patent application No. 09/947733, "Method and System for Improving the Efficiency of the Set and Offset Strapson a Magnetic Sensor" ("Witcraft et al II")

Witcraft et al II provides a method for manufacturing a magnetic field sensor comprising the step of manufacturing a holder material approximating a magnetic field sensing structure. The sensor includes a substrate, a current strip, and the magnetic field sensing structure.

Witcraft et al II also provides a set-reset or offset band as the current band. This embodiment may also include a set-reset strap and an offset strap in the same sensor. In another embodiment, the magnetic field sensing structure also includes permalloy strips that are interconnected to each other and to output terminals that produce an indication of the magnetic field.

(7) U.S. patent application No. 10/002454 to Wan et al, entitled "360-Degree rotate Position Sensor" ("Wan et al II")

In U.S. patent application Wan et al II, the 360 degree rotational position sensor includes a Hall (Hall) sensor and an MR sensor. A magnet or the 360 degree rotational position sensor is mounted on the rotational shaft. The 360 degree rotational position sensor is positioned substantially close to the magnet so that the 360 degree rotational position sensor is able to detect the magnetic field generated by the magnet. The hall sensor detects the polarity of the magnetic field. The MR sensor detects angular positions of the magnetic field up to 180 degrees. The combination of the output of the hall sensor and the output of the MR sensor can provide angular position sensing of magnetic fields up to 360 degrees.

(8) U.S. Pat. No. 5521501 to Dettmann et al, entitled "Magnetic Field Sensor Constructed from a reconstruction Lineard One Magnetic resistance and Magnetic resistance of Magnetic resistance and resistance" ("Dettmann et al")

Dettmann et al provides a single magnetic field dependent resistor comprising one or more MR film strips on a highly conductive thin film conductor strip disposed in an insulating manner perpendicular to the longitudinal direction of the magnetic field dependent resistor. The high-conductive thin-film conductor strip is provided with a bent structure. In order to generate an electrical resistance in the case of a current flow, despite the presence of curved strips arranged adjacent to one another and having alternating magnetic field directions, the resistance of which changes isotropically in all sub-regions under the influence of the field to be measured, the MR film strip is divided into regions having a Barber pole structure with an inclination angle opposite to the longitudinal direction of the strip.

Advantageously, the bending of the highly conductive thin film conductor strip leads to the situation: a reversal of the magnetization direction requires only a small current. Moreover, since the magnetic fields of the bending strips arranged adjacent to each other largely cancel each other out due to their opposite directions, the stray magnetic fields present outside the sensor chip are very low. The magnetic field sensors can then be operated very close to each other. For the same reason, the alternating magnetized conductor also has a very low inductance, so that the limitation of the measuring frequency due to the inductance no longer occurs.

When the magnetic field sensor works with the MR resistor, a constant current is fed to the MR resistor. The measured voltage of the MR resistor is used as an output signal. When a current pulse of a certain direction is passed through the highly conductive thin film conductor strip, the self-magnetization in the region of the MR resistor is set in a certain way. In this state, the magnetic field to be measured causes the resistance value of the MR resistor to increase. This means that the output signal is larger than in the absence of a magnetic field. If a current pulse, now in the opposite direction to the previous pulse, is fed into the highly conductive thin film conductor strip, the direction of the self-magnetization reverses. The magnetic field to be measured then causes the resistance to decrease and the output voltage to be smaller than in the absence of the magnetic field. With the changing direction of the pulse, an AC voltage is then present at the output, whose amplitude is proportional to the magnetic field to be measured. Any effects, such as temperature, that cause small shifts in the resistance values of the MR film strips do not affect the AC output voltage. However, a decrease in the MR effect is perceived due to the increase in temperature in the amplitude of the output AC voltage.

Thus, in another embodiment, another highly conductive thin film strip is disposed below each MR film strip. The current through the strips is controlled by the sensor output voltage so that the applied magnetic field to be measured is exactly cancelled by the current. In this case, the MR magnetic field sensor functions as a zero detector. The output of the arrangement is the amount of compensation current, which is independent of the temperature of the arrangement. Likewise, the non-linearity no longer plays a role in the sensor characteristic because the sensor is not modulated.

In a further embodiment of the Dettmann et al patent, four parallel MR resistors each comprising a plurality of regions are disposed over the thin layer of alternating magnetization conductor and the highly conductive compensating conductor. These regions are provided with a basheer rod structure of alternating positive and negative angles from the longitudinal direction of the MR film strip, such that they start with alternating regions of positive and negative basheer rod structure angles, respectively. These four resistors are connected together to form a Wheatstone bridge. If the alternately magnetized conductor is again operated with pulses of alternately opposite directions, an AC voltage signal appears at the output of the bridge. Only one dc voltage signal is superimposed on this signal, which results from the fact that the four resistance values of the bridge may differ. However, the dc voltage component is much smaller than when using a single resistor which allows simple evaluation. Of course, compensation of the magnetic field to be measured can also be used here.

The bridge design may include four resistors formed from an even number of regions. Only the angular order of the babbitt structure changes from one resistor to another. The direction of alternating magnetization is set in this region by a first high current pulse flowing through the alternating magnetization conductor. The sensor bridge can then sense the magnetic field and can be used in a conventional manner without alternating magnetization. Because all four resistors of the bridge comprise the same area, the same change will occur in all resistors as the temperature of the sensor design changes. This also applies to the changing component due to the variable layer voltage and subsequently due to the alternating magnetization. The sensor bridge thus has a reduced zero point compared to known sensor bridge designs and is therefore also suitable for measuring smaller fields in normal operation. The constant current through the alternating magnetized conductor can be used to generate a certain steady magnetic field, by which a certain sensor sensitivity can be set. The arrangement of Dettmann et al can thus be advantageously used in the application of different evaluation methods for magnetic field measurements.

Exemplary Metal-insulator-Metal capacitor integration

To provide the functionality of the set/reset driver circuit, the device 200 of fig. 2 may include a plurality of semiconductor device components. In addition, one or more specific capacitors may be included, such as a metal-insulator-metal (MIM) capacitor 305 shown in the first dielectric layer 206. As shown, the MIM capacitor 305 is located between contact V1 and the nitride layer overlying the low resistance metallization M1. Although the MIM capacitor 305 is shown located in the first dielectric layer 206, it may alternatively be located in other locations, such as in the passivation layer 202, the second dielectric layer 204, or in the CMOS/Bipolar bottom layer 210. The integrated MIM capacitor is an improvement over the linear capacitor used with existing MR sensors because of its reduced size, which may make the overall package smaller.

The device 200 is the preferred configuration for an MR sensor, and other configurations having different permalloy arrangements and structures may be used instead. In yet another embodiment, the MIM capacitor 305 may be included in the device 200 and the CMOS/Bipolar bottom layer 210 may be omitted or other base layer or substrate materials may be used instead.

Integrated or integrated set/reset circuit

The schematic diagram of fig. 3 depicts set/reset circuits 360, 362 with MR sensors according to an exemplary embodiment that may be implemented on-die (on-die) or monolithically integrated. The circuit design shown in fig. 3 is only one of many possible designs and is not meant to be limiting in any way.

Exemplary circuit 360 is an amplification circuit to increase the signal gain of the MR sensor. When sensing across the legs of the magnetoresistive bridge, two operational amplifiers with negative feedback loops provide differential voltage signals representative of local magnetic field variations. The resistor values shown are particularly well suited for the preferred embodiment, and other resistor values and configurations may be more suitable for other MR sensor designs. Similarly, although two operational amplifiers are shown for circuit 360, other designs may use more or fewer operational amplifiers and may include more or fewer bias resistors.

An exemplary circuit 362 is a switching circuit that generates set/reset current pulses through the set/reset strap to properly orient the thin film magnetic domains of the bridge circuit in the proper direction. Circuit 362 includes a pair of complementary field effect transistors that are switched by the ESDR relay to provide the set/reset pulse. Similar to circuit 360, design choices for a particular magnetoresistive sensor may require changes to the switching circuit. This resistor value is shown for the preferred embodiment.

The circuit 364 is fully optional and may be used for testing purposes. It shows this flexibility: many application specific features may be included in the set/reset driver circuit without departing from the scope of the present invention. Various modifications may be made to all of the circuits shown in fig. 3. For example, thermal or temperature compensation circuitry may be included to prevent thermal drift.

Exemplary semiconductor Circuit integration

Fig. 4 is a plan view of one embodiment of a device 300 in which the set/reset driver circuitry is integrated on-chip or monolithically integrated with the MR sensor. Exemplary components of the device 300 include a magnetoresistive bridge 301, a set/reset strap 302, an offset strap 304, a set/reset circuit 306, 308, a laser trim point 310 (for matching the impedance of the legs of the bridge 301), an ESD protection diode 312, a MIM capacitor 314, an operational amplifier 316, a contact 318, and a test point 320. For further information reference may be made to the patents and patent applications included above.

The simplified circuit diagrams 500-600 of fig. 5-6 depict an exemplary type of semiconductor circuit that may be integrated with an MR sensor. These exemplary figures are not an exhaustive or fixed list of circuits that may be integrated with or to the MR sensor, but illustrate the breadth of circuits that may be so combined.

The simplified circuit diagram 500 of FIG. 5 depicts a compass circuit 502 that may be integrated with the MR sensor. In this embodiment, the MR sensor can be formed from first and second magnetoresistive sensing elements 504, 506. The first and second magneto-resistive-sensing elements 504, 506 may sense orthogonal magnetic fields and responsively provide first and second outputs. In a three-dimensional coordinate system, for example, the first magnetoresistive sensing element 504 can sense a magnetic field in the "X" direction, and the second magnetoresistive sensing element 506 can sense a magnetic field in the "Y" direction. The X-Y plane can of course be rotated by the coordinate system.

Reorientation elements in the form of one or more set/reset and/or offset strips (not shown) may be formed on or integrated with first and second magneto-resistive-sensing elements 504, 506. As described above, these reorientation elements may be used to control and adjust the sensing characteristics of the first and second magneto-resistive-sensing elements 504, 506.

The compass circuit 502 may include: (i) an offset band driver circuit 508 for performing offset adjustment of the first and/or second magneto-resistive-sensing elements 504, 506; (ii) a set/reset band driver circuit 510 for completing a set/reset sequence of the first and/or second magneto-resistive-sensing elements 504, 506; and (iii) first and second differential amplifiers 512, 514 for functionally regulating the outputs of the first and second magneto-resistive-sensing elements 504, 506, respectively. The tape driver circuit 508, the set/reset tape driver circuit 510, and the first and second differential amplifiers 512, 514 may be arranged in the same package as the first and second magneto-resistive-sensing elements 504, 506. Alternatively, the circuit may be monolithically formed on the same die as the first and second magneto-resistive-sensing elements 504, 506.

The compass circuit 502 may include a temperature compensation circuit to counter adverse temperature effects of the MR sensor. The temperature compensation may be in the form of, for example, a thermistor, a permalloy element, and/or an active-regulation (active-regulation) circuit. The active conditioning circuit may sense changes due to temperature effects, i.e., increases or decreases in voltage or current, and then provide compensation in the form of voltage and/or current in response.

The compass circuit 502 may also include other components. Further details regarding the components of compass circuit 502 may be found in the present specification and in the patents and patent applications incorporated above.

The simplified circuit diagram 600 of FIG. 6 depicts a second compass circuit 602 into which the MR sensor is integrated. In this embodiment, the MR sensor can be formed from first, second and third magneto-resistive-sensing elements 604 and 608, which can sense three orthogonal magnetic fields. The first and second magneto-resistive-sensing elements 604 and 606 may be fabricated on a first die, while the third magneto-resistive-sensing element 608 may be fabricated on a second die. Although the second die may be packaged with the first and second magneto-resistive-sensing elements 604, 606, in this embodiment, the second die is not so packaged.

In a three-dimensional coordinate system, the first magneto-resistive-sensing element 604 may sense a magnetic field in the "X" direction, and the second magneto-resistive-sensing element 606 may sense a magnetic field in the "Y" direction. The third magneto-resistive-sensing element 608 may sense a magnetic field in the "Z" direction.

Similar to compass circuit 502, reorientation elements in the form of one or more set/reset and/or offset bands (not shown) may be formed on or integrated with first, second and third magneto-resistive-sensing elements 604-608. The compass circuit 602 may also be arranged with a set/reset band driver circuit 610 and first, second and third differential amplifiers 612 and 616. The set/reset strap driver circuit 610 may complete the set/reset sequence for the first, second, and/or third magneto-resistive-sensing elements 604 and 608. The first, second and third differential amplifiers 612 and 616 may be used to functionally regulate the outputs of the first, second and third magneto-resistive-sensing elements 604 and 608, respectively.

In this embodiment, the set/reset band driver circuit 610 and the first, second and third differential amplifiers 612 and 616 may all be formed on the first die. However, assuming that the third magneto-resistive-sensing element 608 and the set/reset strap can be formed on the second die, the set/reset strap driver circuit 610 and the third differential amplifier 616 can be interconnected with the second die. Thus, a set/reset pulse applied to compass circuit 602 at node 618 may be output to set/reset interface 620 through the first die and transmitted to the second die to perform a set/reset sequence for the third magneto-resistive-sensing element 608. Similarly, the output signal of the third magneto-resistive-sensing element 608 destined for the third differential amplifier 616 may be communicated to the first die through the sensor interface 622.

In an alternative form of embodiment, the set/reset band driver circuit 610 and some of the first, second and third differential amplifiers 612 and 616 may be formed on the first die. Other portions, such as the set/reset band driver circuit 610 and the third differential amplifier 616, may be formed on the second die and interconnected with the first die. As those skilled in the art will recognize, other combinations of components of the compass circuit 602 are possible.

Similar to the compass circuit 502, each of the differential amplifiers 612-616 may be arranged with an optional adjustable offset and gain to advantageously compensate and/or eliminate unwanted changes in the magnetoresistive elements 604-608. The compass circuit 602 may also include temperature compensation circuitry, as described above, to counter adverse temperature effects of the MR sensor.

Exemplary Process for integrating semiconductor Components with MR Sensors

Table 1 below illustrates a simplified exemplary process for integrating one or more semiconductor device components, such as for setting/resetting circuitry with an MR sensor. Such processing is believed to be unique in that semiconductor foundries have previously been spared from contaminating the materials typically used in the manufacture of magnetic sensors with their processing. In addition, companies in the magnetic industry (e.g., disk drive head manufacturers, etc.) have been separated from electronics companies, and their specialized manufacturing techniques have been kept largely separate from each other.

Table 1: sample manufacturing process

Cleaning wafer
	Oxide and nitride diffusion, lithography, etching, cleaning (device specific construction)
Boron/phosphorus implant (if any), clean
	(end front-end processing; begin back-end processing)
Depositing contact glass (if any), reflowing
	Sputtering, etching, NiFe mask, photoetching (device place)Specific construction)
Dry etch metallization, deposition and build-up of dielectric (e.g., TEOS), planarization (device specific build-up)
	Examination and evaluation

In a preferred embodiment, the semiconductor device processing is done at the front end, while the lithography and etching steps associated with manufacturing the MR sensor are done at the back end. Table 1 is intended to be generally applicable to many MR sensor manufacturing processes and thus does not include details as to how a particular configuration is obtained. The construction shown in fig. 2 includes several iterations of back-end steps to obtain multiple dielectric layers and metallization layers. Of course, additional cleaning and other steps may be performed as appropriate.

Devices having set/reset driver circuits integrated with MR sensor devices and exemplary processing options have now been described. Since such integrated devices can be manufactured as a single chip, advantages that a user can achieve include, among other things, a reduction in size and an increase in functionality.

Conclusion

In the preceding detailed description, numerous specific details are set forth in order to provide a thorough understanding of the exemplary embodiments herein. It will be understood, however, that the embodiments may be practiced without these specific details. In other instances, well-known methods, procedures, components and circuits have not been described in detail so as not to obscure the description.

Moreover, the disclosed embodiments are merely exemplary and other embodiments may be used in place of, or in combination with, the disclosed embodiments. Moreover, in addition to the above-described techniques, it is contemplated that the above-described devices and components may be fabricated using silicon/gallium arsenide (Si/GaAs), silicon/germanium (SiGe), and/or silicon carbide (SiC) fabrication techniques. These technologies include Heterojunction Bipolar Transistor (HBT) manufacturing processes, and/or metal semiconductor field effect transistor (MESFET) manufacturing processes.

The exemplary embodiments described herein may be arranged in a variety of devices and other apparatuses that may include or may be used with any suitable voltage source, such as batteries, alternators, and the like, to provide any suitable voltage, such as approximately 0.4, 5, 10, 12, 24, and 48 volts DC, and approximately 24 and 120 volts AC, and the like.

Exemplary embodiments have been described and illustrated. Further, the claims should not be read as limited to the described order or elements unless stated to that effect. In addition, the use of the word "devices" in any claim is intended to invoke 35u.s.c. $112, 6, and claims without the word "devices" are not so intended.

Claims (10)

1. A sensing device, comprising:

at least one magneto-resistive-sensing element;

at least one reorientation element for conditioning the at least one magneto-resistive-sensing element; and

a semiconductor circuit having a driver circuit for controlling the at least one reorientation element, wherein the at least one magneto-resistive-sensing element, the at least one reorientation element, and the semiconductor circuit are arranged in a single package, and wherein at least a portion of the semiconductor circuit is formed integrally with the at least one magneto-resistive-sensing element on a first chip, wherein at least a portion of the semiconductor circuit is formed on a second chip.

2. The sensing apparatus of claim 1, wherein the first and second chips are electrically connected together.

3. The sensing apparatus of claim 1, wherein the first chip is placed orthogonally to the second chip.

4. The sensing apparatus of claim 1, wherein the second chip is placed in proximity to the first chip.

5. The sensing apparatus of claim 4, wherein the first and second chips are electrically connected together.

6. The sensing apparatus of claim 4, wherein the first and second chips are free of electrical connections, wherein any electrical interaction is independent of electrical connections.

7. The sensing apparatus of claim 1, wherein the first magneto-resistive-sensing element and the first portion of the semiconductor circuitry are formed on a first chip and the second magneto-resistive-sensing element and the second portion of the semiconductor circuitry are formed on a second chip.

8. The sensing apparatus of claim 7, wherein the first portion of the semiconductor circuit comprises a driver circuit for controlling the first reorientation element to adjust the first magneto-resistive-sensing element, and the second portion of the semiconductor circuit comprises a driver circuit for controlling the second reorientation element to adjust the second magneto-resistive-sensing element.

9. The sensing apparatus of claim 7, wherein at least one amplifier is included in at least one of the first and second portions of the semiconductor circuit.

10. The sensing apparatus of claim 1, wherein the driver circuit comprises at least one of functional adjustment, signal conditioning, and electrostatic discharge protection circuitry.