(19)
(11)EP 2 752 676 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
10.03.2021 Bulletin 2021/10

(21)Application number: 12828008.8

(22)Date of filing:  27.08.2012
(51)Int. Cl.: 
G01R 33/09  (2006.01)
G01R 33/06  (2006.01)
G01R 33/07  (2006.01)
G01R 33/02  (2006.01)
(86)International application number:
PCT/CN2012/080600
(87)International publication number:
WO 2013/029510 (07.03.2013 Gazette  2013/10)

(54)

TRIAXIAL MAGNETIC FIELD SENSOR

DREIACHSIGER MAGNETFELDSENSOR

CAPTEUR DE CHAMP MAGNÉTIQUE À AXE TRIPLE


(84)Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

(30)Priority: 30.08.2011 CN 201110251902

(43)Date of publication of application:
09.07.2014 Bulletin 2014/28

(73)Proprietor: Multidimension Technology Co., Ltd.
Free Trade Zone Zhangjiagang, Jiangsu 215634 (CN)

(72)Inventors:
  • LEI, Xiaofeng
    Zhangjiagang Jiangsu 215600 (CN)
  • ZHANG, Xiaojun
    Zhangjiagang Jiangsu 215600 (CN)
  • LI, Wei
    Zhangjiagang Jiangsu 215600 (CN)
  • XUE, Songsheng
    Zhangjiagang Jiangsu 215600 (CN)

(74)Representative: HGF 
1 City Walk
Leeds LS11 9DX
Leeds LS11 9DX (GB)


(56)References cited: : 
EP-A1- 2 003 462
WO-A1-2007/065377
WO-A1-2009/137802
CN-A- 101 813 479
CN-A- 102 385 043
CN-U- 202 210 145
US-A1- 2008 272 771
US-A1- 2009 315 129
US-A1- 2011 074 406
WO-A1-2006/070305
WO-A1-2009/119346
CN-A- 1 356 559
CN-A- 101 813 479
CN-A- 102 426 344
CN-U- 202 362 441
US-A1- 2009 115 405
US-A1- 2010 253 330
US-A1- 2011 147 867
  
      
    Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


    Description

    TECHNICAL FIELD



    [0001] The invention relates to the design of the bridge type magnetic field sensor, in particular a three-axis magnetic field sensor.

    BACKGROUND ART



    [0002] In recent years Magnetic Tunnel Junctions (MTJ) have begun finding acceptance in industrial applications as a new type of magnetoresistive sensor, using the Tunneling Magnetoresistance (TMR) Effect of magnetic multilayer materials. In this effect the magnitude and direction of a magnetic field applied to the multilayered film changes the resistance of the multilayer film. The TMR effect is larger than the AMR (Anisotropic Magnetic Resistance) effect, and it also known to have better temperature stability than the Hall Effect. As a result, TMR magnetic field sensors have the advantages of higher sensitivity, lower power consumption, better linearity, wider dynamic range, better temperature characteristics, and lower noise than AMR, GMR, or Hall devices. Moreover, MTJs can be easily fabricated with existing chip manufacturing technology which facilitates the production of very small integrated magnetic field sensors.

    [0003] Multi-axis magnetic field sensors generally have more than a single sensor chip integrated in the package, in order to provide vector measurement capability with good orthogonality. Because the magnetic field is a vector field, a multi-axis magnetic field sensor has a very wide range of applications, especially for electronic compass, which use biaxial or triaxial sensors for geomagnetic field measurements. As a result of this common application, simplified means of production of highly-integrated single-chip multi-axis magnetic field sensors are strongly desired.

    [0004] When deposited on the same wafer, GMR and MTJ materials used for the different sensor axes have the same magnetic moments, and after annealing have the same pinned layer direction, which makes fabrication of single-chip three-axis sensors difficult. As such, the most common approach to manufacture a GMR triaxial sensor is to package an X-axis sensor, a Y-axis sensor, and a Z-axis sensor deposited on three different substrates; such a GMR triaxial sensor suffers limitations such as excessive size, high packaging cost, and it has a lower sensitivity and higher power consumption than a MTJ sensor.

    [0005] As can be seen from the above, current AMR, Hall, and GMR triaxial sensors are disadvantageous in that they have excessive size, high packaging cost, lower sensitivity, higher power consumption, and the manufacturing methods are impractical.

    [0006] US2011/0147867 discloses a method of vertically mounting an integrated circuit. WO2009/137802A1 discloses a two-axis magnetic field sensor with multiple pinning directions and method to produce the sensor.

    SUMMARY OF THE INVENTION



    [0007] To resolve the above problems, the present invention provides a compact triaxial sensor with higher sensitivity and lower power consumption.

    [0008] There is provided a triaxial magnetoresistive sensor in accordance with the appended claims.

    [0009] Preferably, the Z-axis magnetic field sensor is a MTJ sensor positioned on and parallel with the substrate using a solder bump connection, wherein the Z-axis magnetic field sensor has a sensing direction perpendicular to the surface of the Z-axis sensor.

    [0010] Alternatively, the Z-axis magnetic field sensor is a MTJ magnetic field sensor with the sensitive direction parallel to the chip surface, and the Z-axis MTJ sensor is vertically disposed on the substrate using a solder bump connection.

    [0011] Alternatively, the Z-axis magnetic field sensor is a MTJ sensor, wherein the Z-axis sensor chip comprises magnetoresistive elements mounted onto oppositely inclined surfaces of the substrate.

    [0012] Alternatively, the Z-axis magnetic field sensor is a Hall Effect or giant Hall Effect magnetic field sensor.

    [0013] Preferably, the triaxial magnetic field sensor element, the insulation layer, the ASIC, and the substrate are stacked, and said insulation layer is provided with copper conductors positioned to connect said three-axis magnetic field sensor element and said ASIC.

    [0014] Preferably, the insulation layer, the ASIC, the substrate, and the triaxial sensor element are stacked, and copper conductor are positioned on the substrate in order to electrically connect the triaxial sensor element with the ASIC.

    [0015] Preferably, the copper conductors are fabricated using silicon via (TSV) technology.

    [0016] Preferably, the Z-axis magnetic field sensor is a perpendicular magnetic anisotropy MTJ sensor chip having a film surface positioned horizontally on the substrate, wherein the sensing direction of the Z-axis sensor is perpendicular to the surface of the Z-axis MTJ sensor chip.

    [0017] Alternatively, the Z-axis magnetic field sensor is a Hall Effect or a giant Hall Effect magnetic field sensor chip.

    [0018] Preferably, the Z-axis sensor is a MTJ sensor, said Z-axis sensor comprises MTJ magnetoresistive elements mounted onto oppositely inclined surfaces of the substrate and electrically connected with the substrate by solder bumps to form the Z-axis sensor, and the Z-axis sensor is electrically and physically connected with the ASIC by a copper conductor.

    [0019] The above design provides a highly integrated sensor with high sensitivity, low power consumption, good linearity, wide dynamic range, excellent thermal stability, and low magnetic noise.

    BRIEF DESCRIPTION OF THE DRAWINGS



    [0020] 

    Figure 1 is a schematic drawing of the magnetic resistance of a magnetic tunnel junction element.

    Figure 2 is a schematic drawing of an MTJ element with perpendicular magnetic anisotropy.

    Figure 3 is a graph of the ideal output of an MTJ element.

    Figure 4 is a graph of the ideal output of a perpendicular magnetic anisotropy MTJ element

    Figure 5 is a schematic diagram of MTJ elements electrically connected in series.

    Figure 6 is a schematic diagram of the Hall or giant Hall element.

    Figure 7 is a graph of the ideal output of a Hall element.

    Figure 8 is a schematic diagram of a MTJ push-pull bridge sensor.

    Figure 9 is a plot of the analog output of a MTJ push-pull bridge sensor.

    Figure 10 is a schematic diagram of a MTJ referenced bridge sensor.

    Figure 11 is simulation plot of the output of a MTJ referenced bridge sensor.

    Figure 12 is a schematic view of a type of single-chip biaxial magnetic field sensor.

    Figure 13 is a schematic view of the MTJ sensor Z-axis magnetic field sensor fixed on an incline.

    Figure 14 is a schematic diagram of the Z-axis mounted perpendicular to the MTJ bridge sensor.

    Figure 15 is a schematic view of the chip stack and wire bonding process used to achieve a triaxial magnetic field sensor.

    Figure 16 is a schematic diagram of the triaxial magnetic field sensor flip-chip process.

    Figure 17 is a schematic diagram of a single chip MTJ triaxial magnetic sensor.

    Figure 18 is a schematic view of another single-chip MTJ triaxial magnetic sensor.



    [0021] In the figures, 1 is a MTJ element; 2 a Magnetic pinned layer; 3 an antiferromagnetic layer; 4 a ferromagnetic layer; 5 a tunnel barrier layer; 6 a ferromagnetic free layer; 7 the magnetic direction of the ferromagnetic free layer; 8 the magnetic direction of the ferromagnetic pinned layer; 9 an applied magnetic field; 10 a sensing direction; 11 a seed layer; 12 an upper electrode; 13 the resistance of an MTJ element; 14 The low resistance value of an MTJ element; 15 the high resistance value of an MTJ element; 16 electric current; 17 a permanent magnet; 18 a substrate; 19 an ASIC; 20. a MTJ bridge sensor; 21 a solder bump; 22 an X-axis bridge sensor; 23 a Y-axis bridge sensor; 24 a Z-axis sensor; 25 a gold bond wire; 26 a solder bump; 27 an insulation layer; 28 a copper conductor; 29 a biaxial sensor; 30 a triaxial sensing element; 41 The direction of the magnetization of the free layer R1; 42 The direction of the magnetization of the free layer R2; 43 The direction of the magnetization of the free layer R3; 44 The direction of the magnetization of the free layer R4.

    DESCRIPTION OF THE PREFERRED EMBODIMENTS



    [0022] Below in conjunction with the accompanying drawings, Figures 1-18, preferred embodiments of the present invention are elaborated, such that the advantages and features of the appended claims are more easily understood by those skilled in the art.

    Tunnel junction magnetoresistance overview:



    [0023] Figure 1 is a schematic view of a standard MTJ element. The standard MTJ element 1 includes a free ferromagnetic layer 6, a ferromagnetic pinned layer 2, and a tunnel barrier layer 5 between the ferromagnetic layers. The free ferromagnetic layer 6 is composed of a ferromagnetic material, and the magnetization direction of the ferromagnetic free layer is able to change in response to an external magnetic field. The ferromagnetic pinning layer 2 has a magnetization direction that is pinned in one direction, and it does not change under general operating conditions. A ferromagnetic pinned layer 2 may be either at the top or bottom of the antiferromagnetic layer 3. The MTJ structure is usually deposited on top of a conductive seed layer 11, while an electrode 12 is usually deposited on top of the MTJ structure. The resistance of the MTJ element is measured between the seed layer 11 and the upper electrode layer 12, and its value 13 is representative of the relative orientation of the magnetizations of the ferromagnetic free layer 6 and the ferromagnetic pinned layer 2.

    [0024] Figure 2 is a schematic diagram of a perpendicular magnetic anisotropy MTJ element. The difference between the standard MTJ element and a perpendicular magnetic anisotropy MTJ element is the ferromagnetic pinning layer magnetization direction 8 and the magnetization direction of the ferromagnetic free layer 7 are aligned along the direction perpendicular to the film surface, that is, the sensitive direction of the MTJ is perpendicular to the film (chip) surface. A perpendicular magnetic anisotropy MTJ element has the same seed layer 11 as the standard MTJ element, and likewise the resistance value 13 is measured between the upper electrode layer 12 and the seed layer 11, and it represents the relative orientation of the magnetization of the ferromagnetic free layer 6 and the ferromagnetic pinned layer 2.

    [0025] Figure 3 is an ideal output response curve of an MTJ element, the output curve in the low-resistance state RL 14 and the high-impedance state RH 15, represent the low-resistance state 14 and the high-resistance state 15 of the saturated MTJ. When the magnetic free layer 7 magnetization direction and magnetic pinning layer 8 direction of magnetization are parallel, the measured resistance value 13 of the MTJ is the low-resistance state; when the magnetization direction of the ferromagnetic free layer 7 and the magnetization direction of the ferromagnetic pinned layer 8 are anti-parallel, the resistance value of the MTJ element 13 is the high-resistance value 15. By known techniques, the resistance of the MTJ element 1 is made linear as a function of applied magnetic field in the magnetic field range between the high-resistance state and the low resistance state, the saturation fields -Hs and Hs then define the linear range of the MTJ element.

    [0026] Figure 4 illustrates the ideal response of a perpendicular magnetic anisotropy MTJ element. When the component of the applied field parallel to the film surface is 0, the output curve of the perpendicular magnetic anisotropy MTJ element can have high sensitivity and low saturation field. However, in the usual case, the external field component of a direction parallel to the film surface direction is not 0, and under such conditions, the perpendicular magnetic anisotropy MTJ element has low sensitivity, high saturation field Hs value compared to a standard MTJ element, but relative to the Hall and giant Hall element it is much better and thus advantageous.

    [0027] Figure 5 is a schematic view of several MTJs connected in series to form a magnetoresistive element. A string of connected MTJs 1 can reduce noise and improve the stability of the sensor. In MTJ magnetoresistive element 24, the bias voltage of each MTJ 1 is decreased proportionally to the number of MTJs in the string. This reduces the current required to generate a large voltage output, thereby reducing the shot noise, and it also improves the ESD tolerance of the sensor. In addition to improving the output signal and increasing ESD tolerance, increasing the number of MTJs improves noise performance because uncorrelated random behavior of each individual MTJ element is averaged out.

    [0028] Figure 6 is a schematic view of a Hall or giant Hall element. Here, Iin + and Iin- are current input and output terminals, V1 and V2 are the voltage output terminals. When a steady current I+ flows between Iin- and Iin+, a magnetic field (the direction perpendicular to the plane formed by the current terminals and the voltage terminals) applied to the Hall or giant Hall element, will generate a differential voltage between terminals V1 and V2. The ideal output curve is shown in Figure 7.

    Push-pull bridge sensor design:



    [0029] Figure 8 is a schematic diagram of a MTJ push-pull full-bridge sensor. The four MTJ elements R1, R2, R3, and R4 are interconnected as a full-bridge, and each MTJ element is composed of one or a plurality of MTJs 1 connected in series (Figure 2). For each of the magnetoresistive elements the magnetization direction of the pinned layer is the same, and the freelayer magnetization direction with respect to the pinned layer magnetization direction at is at an angle θ (between 30° to 90°), and this angle θ is the same magnitude. Magnetoresistive element pairs (R1 and R3, R2 and R4) have the same free layer magnetization direction (41 and 43, 42 and 44), while magnetoresistive elements located adjacent to each other (R1 and R2, R3 and R4) have freelayer magnetization aligned in different directions (41 and 42, 43 and 44). In this specific full-bridge configuration, the sensitive direction 10 is perpendicular to the ferromagnetic pinned layer's magnetization direction 8. Because the magnetization direction of the magnetic pinned layer 8 of each of the magnetoresistive elements is the same, this push-pull full bridge sensor design can be implemented on a single chip to form a push-pull full bridge sensor, without the use of a multi-chip packaging process or the need to perform local laser heating.

    [0030] When a magnetic field is applied along the sensitive direction 10, it changes the relative orientation of the freelayer magnetization relative to the pinned layer magnetization. Therefore, magnetoresistive elements such that R1 and R3 show a resistance increase while the other two magnetoresistive elements R2 and R4 show a decreasing resistance. When the magnetic field is applied in the opposite direction then R1 and R3 resistance will be reduced while R2 and R4 resistance will be increased. The use of a combination of two pairs of magnetoresistive elements that have opposite response to the applied field, that is, a pair of MTJ elements has a resistance that increases while the other has a resistance that decreases, effectively doubling the response of the bridge circuit, produces what is called a "push-pull" bridge. In the ideal case, if the resistance value of resistor R1= (R1 + ΔR), R3 = (R1 + ΔR), R2=(R2 - ΔR), and R4=(R2 - ΔR), the bridge output becomes:

    Ideally, when R1 = R2> ΔR, the equation can be simplified:

    The simulated response for this push-pull bridge circuit is shown in Figure 9.

    [0031] The required magnetization angle between the ferromagnetic free layer and the ferromagnetic pinned layer may be achieved in the following ways:
    1. (1) Shape Anisotropy: Use shape anisotropy of the MTJ element to create easy magnetization axes, in order to bias the magnetic free layer magnetization directions. Shape anisotropy of the of the MTJ element is can be adjusted by changing the length relative to the width of the MTJ element, and also by rotating the elements;
    2. (2) Permanent Magnet Bias: Set permanent magnets around the MTJ element to produce a field to bias the free layer magnetization direction;
    3. (3) Coil Bias: Deposit metal wires used to carry a current for generating a magnetic field in layers above or below the MTJ elements, in order to produce a field to bias magnetic free layer directions;
    4. (4) Neel Coupling: Use the Neel Coupling field between the ferromagnetic pinned layer and the ferromagnetic free layer to bias ferromagnetic free layer magnetization;
    5. (5) Exchange Bias: In this technique, weak exchange coupling to an adjacent antiferromagnetic layer on the freelayer creates an effective bias field. The strength can be tuned by placing a Cu or Ta layer between the antiferromagnetic layer and the freelayer, which reduces the strength of exchange bias.

    Referenced Full-Bridge Magnetic Sensor Design:



    [0032] Figure 10 shows a schematic diagram of a referenced full bridge MTJ sensor. Here, four MTJ magnetoresistive elements R1, R2, R3 and R4 are interconnected to form a bridge, and each magnetoresistive element is composed of one or more MTJs connected in series (figure 2). In this design, the output curve of magnetoresistive elements R1 and R3 are strongly dependent on the applied magnetic field 9, and these elements are referred to as the sensing arms. The magnetoresistive response of elements R2 and R4, on the other hand, is only weakly dependent on the applied magnetic field 9, and these elements are called the reference arms. The sensitive direction of this referenced full-bridge structure 10 is parallel to the pinning direction 8. This specific referenced bridge design utilizes the same ferromagnetic pinned layer direction for all bridge arms, and it can thus be built on the same chip as the push-pull full bridge sensor, without the use of a multi-chip packaging process or local laser heating.

    [0033] When a field is applied to the referenced push-pull full bridge sensor, the magnetic field component along the sensitive direction causes the sensor arms R1 and R3 to increase or decrease in resistance, while the reference arm elements R2 and R4 do not change much. In practice, the output of the referenced MTJ full-bridge sensor is linear over a wide field range. A simulation output response curve is shown in Figure 11.

    [0034] In order to build a practical referenced bridge sensor, it is important to set different sensitivities for the sense and reference arms. The sensitivity of a magnetoresistive element is defined as the change in resistance as a function of applied magnetic field:

    It is not practical to reduce the magnetoresistance of the reference arm with respect to the sensor arm, so the relative change in sensitivity between the reference and sense arms is best accomplished by changing Hs. This can be accomplished through any one of or a combination of the following methods:
    1. (1) Magnetic Shielding: A high permeability ferromagnetic layer is deposited over the reference arm in order to attenuate the applied magnetic field;
    2. (2) Shape Anisotropy: Pattern the reference and the sense elements into different sizes, therefore have different shape anisotropy energies and thus different sensitivities. It is most common to vary the length to width ratio of the sensing elements such that the demagnetizing field of the reference elements is much larger than the demagnetizing fields of the sensing elements ;
    3. (3) Exchange Bias: This technique is used to create a bias field on the free layer of the MTJ element perpendicular to the sensitive direction of the MTJ element by using weak exchange coupling to an antiferromagnetic layer. A Cu or Ta barrier layer may be provided between the free layer and the exchange bias layer to reduce the strength of the exchange bias;
    4. (4) In-Stack Bias: In this technique, permanent magnet alloys of Fe, Co, Cr or Pt are deposited onto the surface of the sensor element of the magnetic tunnel junction , and the resulting stray field biases the MTJ element A large magnetic field can then be used to initialize the sensor at different angles. A very important advantage is that the bias field can eliminate the magnetic domains in the MTJ element to improve the stability and linearity of the MTJ element, and the direction of the magnetization can be adjusted to provide great flexibility in tuning the response.

    Single-Chip Biaxial Magnetic Sensor Design:



    [0035] Because the sensors are comprised of magnetoresistive films deposited simultaneously on the same wafer, the pinned layer magnetization directions of the areas used to make different sensor axes are the same. Unfortunately, the biaxial magnetic field sensors consist of two bridge sensors that must be rotated at a 90 ° angle with respect to each other. In the following we will describe the realization of the single chip biaxial magnetic field sensor. Single chip MTJ-axis magnetic field sensor design can be achieved through the following methods or combination of several methods:

    Method 1: Local Laser Heating: After deposition the pinned layers of the different sensor bridges are aligned parallel to each other. A local laser pulse may be applied in the presence of a magnetic field to realign the pinned layer in specific areas;

    Method 2: Multiple Depositions: Different magnetoresistive films may be deposited on different areas of the chip to achieve the correct pinned layer orientation for each sensor.

    Method 3: Referenced/Push-Pull: A single chip MTJ biaxial magnetic field sensor may be achieved as shown on Figure 12. Full bridge and referenced bridge sensors can be developed that are sensitive to fields parallel or perpendicular to the pinned layer direction. These full-bridge sensors can be built on the same substrate using the same steps and the same ferromagnetic pinned layer 8 set direction.


    Triaxial Magnetic Field Sensor Design:



    [0036] A triaxial magnetic sensor includes a substrate, the substrate includes a biaxial magnetic field sensor 29, a Z-axis magnetic field sensor element 24 and an ASIC 19, said biaxial magnetic sensor 29 is integrated onto the substrate 18 and it contains an X-axis the bridge magnetic field sensor 22 sensitive to fields in the X-direction and a Y-axis the bridge magnetic field sensor 23 sensitive to magnetic fields in the Y-direction. Said biaxial magnetic field sensor 29 and the Z-axis magnetic field sensor 24 are connected to the ASIC 19, and each of the X, Y and Z axes are mutually orthogonal. The ASIC is used for signal conditioning.

    [0037] Figure 15 shows a triaxial magnetic field sensor chip fabricated using a stack and wire bond process in which the ASIC element 19 is mated with a biaxial magnetic field sensor 29 chip and a Z-axis magnetic field sensor 24 chip. The biaxial magnetic field sensor 29 includes an X-axis full bridge magnetic field sensor 22 and a Y-axis magnetic field full bridge sensor 23. The biaxial magnetic field sensor 29 and the Z-axis magnetic field sensor 24 are stacked on the surface of the ASIC 19, and gold wire bonds 25 are used to electrically interconnect the biaxial magnetic field sensor 29, the Z-axis magnetic field sensor 24, and the ASIC 19.

    [0038] Figure 16 illustrates the stack and the flip chip process for building a triaxial magnetic field sensor. Here, the ASIC 19 is combined with a biaxial magnetic field sensor 29 and a Z-axis magnetic field sensor 24, where said biaxial magnetic field sensor 29 contains an X-axis bridge magnetic field sensor 22 and a Y-axis bridge magnetic field sensor 23. As shown in Figure 16, the biaxial magnetic field sensor 29 and the Z-axis magnetic field sensor 24 are stacked on the surface of the ASIC 19, and tin solder balls 26 are used to electrically and mechanically connect the biaxial magnetic field sensor 29 and the Z-axis magnetic field sensor 24 to the ASIC 19.

    [0039] In order to provide Z-axis sensing capability, the Z-axis sensor may be achieved by several methods including:
    1. (1) As shown in Figure 13 the MTJ bridge sensors can be built on to an inclined surface. Figure 13 is a schematic view of a MTJ bridge sensor chip attached to an inclined surface, the MTJ sensor chips are sensitive to the magnetic field component parallel to their surface, but in combination can detect the Z-axis component of the field applied, so that they are sensitive only to a field applied in the Z axis direction.
      In a first embodiment of Figure 13, the substrate 18 is wet etched to form the beveled groove, wherein MTJ elements are placed onto opposite slopes and connected through solder bumps to the ASIC component. The relative placement of the MTJ chips can cancel X and Y-axis cross-axis sensitivity and increase sensitivity to fields in the Z-axis direction. To enhance its sensitivity for the Z-axis direction the MTJ sensors can be a full bridges using various implementations including those shown in Figure 8 and Figure 10.
      In the second embodiment of Figure 13, the substrate 18 prepared by wet etching to form the beveled grooves, and then MTJ bridge sensors are placed onto the opposite slopes of the groove and connected to the ASIC 19 through the solder bump, the corresponding placement the of the MTJ bridges can cancel X, Y-axis cross-axis sensitivity and increase sensitivity to fields in the Z-axis direction. The two MTJ bridge magnetic field sensors can be push-pull full bridge sensor (Figure 8) or referenced full-bridge sensors (Figure 2).
    2. (2) Figure 14 shows a vertically mounted MTJ bridge sensor. Figure 14 shows vertically mounted MTJ bridge sensor schematic wherein the edge of the MTJ bridge sensor 20 has solder bumps 21 that are used to set the MTJ bridge sensor 20 onto the ASIC element 19 with a 90° angle, and the solder bump 21 provides electrical connection to the ASIC 19, the chip is now sensitive to Z- axis magnetic field.
    3. (3) As shown in Figure 2, the magnetic field bridge sensors may comprise perpendicular magnetic anisotropy MTJ elements, and these can be configured as a push-pull bridge sensor or as a referenced bridge sensor. The perpendicular magnetic anisotropy MTJ bridge sensor stacked on the ASIC 19 and electrically interconnected thereto;
    4. (4) The Z-axis sensor may be built from Hall Effect or giant Hall Effect sensors. As shown in Figure 6, the output terminals of the Hall Effect sensor or giant Hall Effect sensor are perpendicular to the direction of the current and the applied magnetic field, therefore the sensor can be constructed with output terminals V1 and V2 parallel and current terminals parallel to the film surface, such that placing the sensor on the surface causes the sensor to detect the Z-axis magnetic field.

    Single-Chip Triaxial TMR Magnetic Field Sensor Design:



    [0040] Figure 17 is a schematic diagram of a single chip triaxial MTJ magnetic sensor. Shown in Figure 17, the substrate 18 contains the ASIC 19 circuitry, the surface of the ASIC component is an oxide passivation layer 27, the passivation layer 27 is smoothed using chemical mechanical polishing. After polishing the triaxial magnetic field sensor unit 30 is built onto the ASIC element 19. The triaxial magnetic field sensor unit 30 comprises an X-axis bridge sensor 22, a Y-axis bridge sensor 23, a Z-axis bridge sensor 24. The ASIC 19, the X-axis magnetic field bridge sensor 22, the Y-axis bridge magnetic field sensor 23, the Z-axis magnetic field bridge sensor 24 are electrically interconnected through the copper vias 28. The copper vias 28 may be manufactured using standard semiconductor processes such as coating with photoresist, exposure, plating (deposition), and a second exposure step.

    [0041] For the X-axis sensor, an X bridge type magnetic field sensor 22 is used, and for the Y-axis sensor, a Y-axis the bridge magnetic field sensor 23 is used, and the sensor bridges utilize a conventional MTJ element 1. This implementation is shown in Figure 12.

    [0042] The Z-axis sensor may be a Z-axis magnetic field sensor 24 chips fixed on a slope (Figure 13), it also may be a perpendicular magnetic anisotropy MTJ sensor (see Figure 2), or it could be a Hall or giant Hall Effect magnetic field sensor (Figure 7).

    [0043] Figure 18 is a schematic view of another single chip MTJ-axis magnetic sensor. As shown in Figure 17, the substrate 18 contains the ASIC element 19, an oxide passivation layer 27 on the surface of the ASIC 19, the three-axis magnetic field sensor unit 30 is located at the back surface of the substrate 18, the three-axis magnetic field sensor unit 30 includes bridges sensor for the X-axis 22, Y-axis 23, and Z-axis 24. The ASIC component 19, the X-axis magnetic field sensor 22, the Y axis bridge magnetic field sensor 23, and the Z-axis magnetic field sensor 24 are interconnected through the copper vias 28. The copper vias 28 are through silicon vias manufactured utilizing semiconductor processing, such as wet etching, dry etching, and electroplating (deposition).

    [0044] For the X-axis sensor, an X-axis bridge type magnetic field sensor 22 is used, and for the Y-axis sensor, a Y-axis bridge magnetic field sensor 23 is used. The sensor bridges utilize a conventional MTJ element 1. The implementation is shown in Figure 1.

    [0045] For Z-axis sensing, a Z-axis magnetic field sensor 24 may use MTJ magnetic field sensor chips fixed on a slope (Figure 13), or it also may use a perpendicular magnetic anisotropy MTJ the magnetic field sensor (see Figure 2), or it could also be a Hall Effect or giant Hall Effect magnetic field sensor (Figure 7).

    [0046] The above described embodiments demonstrate specific implementations of the present invention, and obviously other specific implementations exist that do not exceed the scope of the appended claims. It will be apparent to those skilled in the art that various modifications can be made to the present invention without departing from the scope of the appended claims.


    Claims

    1. A triaxial magnetoresistive sensor, comprising:

    a substrate (18);

    a biaxial sensor (29);

    a Z-axis sensor (24) that has a sensing direction along the Z-axis; and

    an ASIC (19),

    wherein the biaxial sensor includes a X-axis bridge sensor (22) that has a sensing direction along the X-axis and a Y-axis bridge sensor (23) that has a sensing direction along the Y-axis, such that any two of the X, Y, and Z axes are mutually orthogonal,
    wherein the Z-axis sensor and the biaxial sensor are both connected with the ASIC
    wherein the X-axis bridge sensor (22) and the Y-axis bridge sensor (23) are MTJ bridge sensors,
    wherein the X-axis bridge sensor (22) and the Y-axis bridge sensor (23) are located on the substrate (18),
    wherein the biaxial sensor (29) is electrically connected to the ASIC (19) by gold bonding wires (25) or using solder bumps (26), and
    characterized in that the X-axis bridge sensor (22) is a referenced full bridge sensor comprising first magnetoresistive elements (1) and second magnetoresistive elements (1) having a weaker magnetoresistive response to applied magnetic field than the first magnetoresistive elements, and
    the Y-axis bridge sensor (23) is a push-pull full bridge sensor comprising magnetoresistive elements (1) with equal magnetoresistive responses to applied magnetic field, in which the magnetization direction magnetic pinned layer (8) of the magnetoresistive elements of the X-axis bridge sensor (22) and the Y-axis bridge sensor (23) is the same.
     
    2. A triaxial magnetoresistive sensor as in claim 1, wherein the Z-axis sensor (24) is a perpendicular magnetic anisotropy MTJ sensor having a film surface, positioned on and parallel with the substrate (18), wherein the Z-axis sensor (24) has a sensing direction perpendicular to the film surface of the Z-axis sensor.
     
    3. A triaxial magnetoresistive sensor as in claim 1, wherein the Z-axis sensor (24) is a MTJ sensor positioned perpendicularly on the substrate (18) and connected to the ASIC (19) by solder bumps (26), wherein the sensing direction of the Z-axis sensor is parallel to the film surface of the Z-axis sensor.
     
    4. A triaxial magnetoresistive sensor as in claim 1, wherein the Z-axis sensor (24) is a MTJ sensor, wherein the Z-axis sensor comprises MTJ magnetoresistive elements (1) mounted onto oppositely inclined surfaces of the substrate (18), and
    the Z-axis sensor is electrically and physically connected with the ASIC by solder bumps (26).
     
    5. A triaxial magnetoresistive sensor claimed by claim 1, wherein the Z-axis sensor is Hall Effect or giant Hall Effect magnetic field sensor.
     
    6. A triaxial magnetoresistive sensor, comprising a substrate (18) provided with a triaxial sensor (30) and an ASIC (19),
    wherein the triaxial sensor includes a X-axis bridge sensor (22) that has a sensing direction along a X-axis, a Y-axis bridge sensor (23) that has a sensing direction along a Y-axis, and a Z-axis sensor (24) that has a sensing direction along a Z-axis, wherein any two of X, Y, and Z axes are mutually orthogonal,
    wherein the X-axis bridge sensor (22) and the Y-axis bridge sensor (23) are MTJ bridge sensors,
    wherein the X-axis bridge sensor (22) and the Y-axis bridge sensor (23) are located on the single substrate (18),
    wherein the triaxial sensor (30) is electrically connected to the ASIC (19), and characterized in that the X-axis bridge sensor (22) is a referenced full bridge sensor comprising first magnetoresistive elements (1) and second magnetoresistive elements (1) having a weaker magnetoresistive response to applied magnetic field than the first magnetoresistive elements, and
    the Y-axis bridge sensor (23) is a push-pull full bridge sensor comprising magnetoresistive elements (1) with equal magnetoresistive responses to applied magnetic field, in which the magnetization direction magnetic pinned layer (8) of the magnetoresistive elements of the X-axis bridge sensor (22) and the Y-axis bridge sensor (23) is the same.
     
    7. A triaxial magnetoresistive sensor as in claim 6, comprising an insulation layer (27) between the triaxial magnetic field sensor element (30) and the ASIC (19), and wherein the insulation layer is provided with copper conductors (28) positioned to achieve electrical interconnection between the components of said triaxial magnetic field sensor element and said ASIC.
     
    8. A triaxial magnetoresistive sensor as in claim 6, comprising an insulation layer (27), wherein the substrate is provided between the triaxial magnetic field sensor element (30) and the ASIC (19), and
    wherein the substrate is provided with copper conductors (28) positioned to achieve electrical interconnection between the components of said triaxial magnetic field sensor element and said ASIC.
     
    9. A triaxial magnetoresistive sensor as in claim 6, wherein the Z-axis sensor (24) is a perpendicular anisotropy MTJ sensor chip having a film surface positioned on and parallel with the substrate (18), such that the sensing direction of the Z-axis sensor is perpendicular to the film surface of the Z-axis sensor chip.
     
    10. A triaxial magnetoresistive sensor claimed by claim 6, wherein the Z-axis sensor is Hall Effect or giant Hall Effect magnetic field sensor.
     
    11. A triaxial magnetoresistive sensor as in claim 6, wherein the Z-axis sensor (24) is a MTJ sensor, said Z-axis sensor comprises MTJ magnetoresistive elements (1) mounted onto oppositely inclined surfaces of the substrate (18) and electrically connected with the substrate by solder bumps (26) to form the Z-axis sensor, and the Z-axis sensor is electrically and physically connected with the ASIC (19) by a copper conductor (28).
     


    Ansprüche

    1. Dreiachsiger magnetoresistiver Sensor, umfassend:

    ein Substrat (18);

    einen zweiachsigen Sensor (29);

    einen Z-Achsensensor (24), der eine Erfassungsrichtung entlang der Z-Achse aufweist; und

    eine ASIC (19),

    wobei der zweiachsige Sensor einen X-Achsen-Brückensensor (22), der eine Erfassungsrichtung entlang der X-Achse aufweist, und einen Y-Achsen-Brückensensor (23) beinhaltet, der eine Erfassungsrichtung entlang der Y-Achse aufweist, sodass beliebige zwei von der X-, Y- und Z-Achse zueinander orthogonal sind,

    wobei der Z-Achsensensor und der zweiachsige Sensor beide mit der ASIC verbunden sind,

    wobei der X-Achsen-Brückensensor (22) und der Y-Achsen-Brückensensor (23) MTJ-Brückensensoren sind,

    wobei sich der X-Achsen-Brückensensor (22) und der Y-Achsen-Brückensensor (23) auf dem Substrat (18) befinden,

    wobei der zweiachsige Sensor (29) durch Goldverbindungsdrähte (25) oder unter Verwendung von Lötperlen (26) elektrisch mit der ASIC (19) verbunden ist, und

    dadurch gekennzeichnet, dass der X-Achsen-Brückensensor (22) ein referenzierter Vollbrückensensor ist, der erste magnetoresistive Elemente (1) und zweite magnetoresistive Elemente (1) umfasst, die eine schwächere magnetoresistive Reaktion auf angelegtes Magnetfeld als die ersten magnetoresistiven Elemente aufweisen, und

    der Y-Achsen-Brückensensor (23) ein Push-Pull-Vollbrückensensor ist, der magnetoresistive Elemente (1) mit gleichen magnetoresistiven Reaktionen auf angelegtes Magnetfeld umfasst, wobei die magnetisch fixierte Schicht (8) in Magnetisierungsrichtung der magnetoresistiven Elemente des X-Achsen-Brückensensors (22) und des Y-Achsen-Brückensensors (23) gleich ist.


     
    2. Dreiachsiger magnetoresistiver Sensor nach Anspruch 1, wobei der Z-Achsensensor (24) ein MTJ-Sensor mit senkrechter magnetischer Anisotropie ist, der eine Filmoberfläche aufweist, der auf und parallel zu dem Substrat (18) positioniert ist, wobei der Z-Achsensensor (24) eine Erfassungsrichtung senkrecht zu der Filmoberfläche des Z-Achsensensors aufweist.
     
    3. Dreiachsiger magnetoresistiver Sensor nach Anspruch 1, wobei der Z-Achsensensor (24) ein MTJ-Sensor ist, der senkrecht auf dem Substrat (18) positioniert und durch Lötperlen (26) mit der ASIC (19) verbunden ist, wobei die Erfassungsrichtung des Z-Achsensensors parallel zu der Filmoberfläche des Z-Achsensensors ist.
     
    4. Dreiachsiger magnetoresistiver Sensor nach Anspruch 1, wobei der Z-Achsensensor (24) ein MTJ-Sensor ist, wobei der Z-Achsensensor magnetoresistive MTJ-Elemente (1) umfasst, die auf entgegengesetzt geneigten Oberflächen des Substrats (18) montiert sind, und
    der Z-Achsensensor durch Lötperlen (26) elektrisch und physisch mit der ASIC verbunden ist.
     
    5. Dreiachsiger magnetoresistiver Sensor nach Anspruch 1, wobei der Z-Achsensensor ein Hall-Effekt- oder ein riesiger Hall-Effekt-Magnetfeldsensor ist.
     
    6. Dreiachsiger magnetoresistiver Sensor, umfassend ein Substrat (18), das mit einem dreiachsigen Sensor (30) und einer ASIC (19) bereitgestellt ist,
    wobei der dreiachsige Sensor einen X-Achsen-Brückensensor (22), der eine Erfassungsrichtung entlang einer X-Achse aufweist, einen Y-Achsen-Brückensensor (23), der eine Erfassungsrichtung entlang einer Y-Achse aufweist, und einen Z-Achsensensor (24) beinhaltet, der eine Erfassungsrichtung entlang einer Z-Achse aufweist, wobei beliebige zwei von der X-, Y- und Z-Achse zueinander orthogonal sind;
    wobei der X-Achsen-Brückensensor (22) und der Y-Achsen-Brückensensor (23) MTJ-Brückensensoren sind,
    wobei sich der X-Achsen-Brückensensor (22) und der Y-Achsen-Brückensensor (23) auf dem einzelnen Substrat (18) befinden,
    wobei der dreiachsige Sensor (30) elektrisch mit der ASIC (19) verbunden ist, und
    dadurch gekennzeichnet, dass der X-Achsen-Brückensensor (22) ein referenzierter Vollbrückensensor ist, der erste magnetoresistive Elemente (1) und zweite magnetoresistive Elemente (1) umfasst, die eine schwächere magnetoresistive Reaktion auf angelegtes Magnetfeld als die ersten magnetoresistiven Elemente aufweisen, und
    der Y-Achsen-Brückensensor (23) ein Push-Pull-Vollbrückensensor ist, der magnetoresistive Elemente (1) mit gleichen magnetoresistiven Reaktionen auf angelegtes Magnetfeld umfasst, wobei die magnetisch fixierte Schicht (8) in Magnetisierungsrichtung der magnetoresistiven Elemente des X-Achsen-Brückensensors (22) und des Y-Achsen-Brückensensors (23) gleich ist.
     
    7. Dreiachsiger magnetoresistiver Sensor nach Anspruch 6, umfassend eine Isolationsschicht (27) zwischen dem dreiachsigen Magnetfeldsensorelement (30) und der ASIC (19), und wobei die Isolationsschicht mit Kupferleitern (28) bereitgestellt ist, die positioniert sind, um elektrische Verbindung zwischen den Komponenten des dreiachsigen Magnetfeldsensorelements und der ASIC zu erreichen.
     
    8. Dreiachsiger magnetoresistiver Sensor nach Anspruch 6, umfassend eine Isolationsschicht (27), wobei das Substrat zwischen dem dreiachsigen Magnetfeldsensorelement (30) und der ASIC (19) bereitgestellt ist, und
    wobei das Substrat mit Kupferleitern (28) bereitgestellt ist, die positioniert sind, um elektrische Verbindung zwischen den Komponenten des dreiachsigen Magnetfeldsensorelements und der ASIC zu erreichen.
     
    9. Dreiachsiger magnetoresistiver Sensor nach Anspruch 6, wobei der Z-Achsensensor (24) ein MTJ-Sensorchip mit senkrechter Anisotropie ist, der eine Filmoberfläche aufweist, die auf und parallel zu dem Substrat (18) positioniert ist, sodass die Erfassungsrichtung des Z-Achsensensors senkrecht zu der Filmoberfläche des Z-Achsen-Sensorchips ist.
     
    10. Dreiachsiger magnetoresistiver Sensor nach Anspruch 6, wobei der Z-Achsensensor ein Hall-Effekt- oder ein riesiger Hall-Effekt-Magnetfeldsensor ist.
     
    11. Dreiachsiger magnetoresistiver Sensor nach Anspruch 6, wobei der Z-Achsensensor (24) ein MTJ-Sensor ist, wobei der Z-Achsensensor magnetoresistive MTJ-Elemente (1) umfasst, die auf entgegengesetzt geneigten Oberflächen des Substrats (18) montiert und durch Lötperlen (26) elektrisch mit dem Substrat verbunden sind, um den Z-Achsensensor zu bilden, und wobei der Z-Achsensensor durch einen Kupferleiter (28) elektrisch und physisch mit der ASIC (19) verbunden ist.
     


    Revendications

    1. Capteur magnétorésistif à axe triple, comprenant :

    un substrat (18) ; un capteur à axe double (29) ;

    un capteur de l'axe des Z (24) qui possède une direction de détection le long de l'axe des Z ; et un ASIC (19),

    ledit capteur à axe double comprenant un capteur en pont de l'axe des X (22) qui possède une direction de détection le long de l'axe des X et un capteur en pont de l'axe des Y (23) qui possède une direction de détection le long de l'axe des Y, de sorte que deux axes quelconques parmi les axes X, Y et Z soient orthogonaux entre eux,

    ledit capteur de l'axe des Z et ledit capteur à axe double étant tous deux raccordés à l'ASIC

    ledit capteur en pont de l'axe des X (22) et ledit capteur en pont de l'axe des Y (23) étant des capteurs en pont MTJ,

    ledit capteur en pont de l'axe des X (22) et ledit capteur en pont de l'axe des Y (23) étant situés sur le substrat (18),

    ledit capteur à axe double (29) étant raccordé électriquement à l'ASIC (19) par des fils métalliques de liaison en or (25) ou à l'aide de billes de soudure (26), et

    caractérisé en ce que le capteur en pont de l'axe des X (22) est un capteur en pont complet référencé comprenant des premiers éléments magnétorésistifs (1) et des seconds éléments magnétorésistifs (1) possédant une réponse magnétorésistive au champ magnétique appliqué plus faible que les premiers éléments magnétorésistifs, et

    le capteur en pont de l'axe des Y (23) est un capteur en pont complet push-pull comprenant des éléments magnétorésistifs (1) avec des réponses magnétorésistives égales au champ magnétique appliqué, dans laquelle la couche piégée magnétique de direction de magnétisation (8) des éléments magnétorésistifs du capteur en pont de l'axe des X (22) et du capteur en pont de l'axe des Y (23) est identique.


     
    2. Capteur magnétorésistif à axe triple selon la revendication 1, ledit capteur de l'axe des Z (24) étant un capteur MTJ à anisotropie magnétique perpendiculaire possédant une surface de film, positionnée sur le substrat (18) et parallèle à celui-ci, ledit capteur de l'axe des Z (24) possédant une direction de détection perpendiculaire à la surface de film du capteur de l'axe des Z.
     
    3. Capteur magnétorésistif à axe triple selon la revendication 1, ledit capteur de l'axe des Z (24) étant un capteur MTJ positionné perpendiculairement sur le substrat (18) et raccordé à l'ASIC (19) par des billes de soudure (26), ladite direction de détection du capteur de l'axe des Z étant parallèle à la surface de film du capteur de l'axe des Z.
     
    4. Capteur magnétorésistif à axe triple selon la revendication 1, ledit capteur de l'axe des Z (24) étant un capteur MTJ, ledit capteur de l'axe des Z comprenant des éléments magnétorésistifs MTJ (1) montés sur des surfaces inclinées opposées du substrat (18), et
    ledit capteur de l'axe des Z étant raccordé électriquement et physiquement à l'ASIC par des billes de soudure (26).
     
    5. Capteur magnétorésistif à axe triple selon la revendication 1, ledit capteur de l'axe des Z étant un capteur de champ magnétique à effet Hall ou à effet Hall géant.
     
    6. Capteur magnétorésistif à axe triple, comprenant un substrat (18) doté d'un capteur à axe triple (30) et d'un ASIC (19),
    ledit capteur à axe triple comprenant un capteur en pont de l'axe des X (22) qui possède une direction de détection le long de l'axe des X, un capteur en pont de l'axe des Y (23) qui possède une direction de détection le long de l'axe des Y, et un capteur de l'axe des Z (24) qui possède une direction de détection le long de l'axe des Z, deux axes quelconques des axes X, Y et Z étant orthogonaux l'un à l'autre,
    ledit capteur en pont de l'axe des X (22) et ledit capteur en pont de l'axe des Y (23) étant des capteurs en pont MTJ,
    ledit capteur en pont de l'axe des X (22) et ledit capteur en pont de l'axe des Y (23) étant situés sur l'unique substrat (18),
    ledit capteur à axe triple (30)
    étant raccordé électriquement à l'ASIC (19), et
    caractérisé en ce que le capteur en pont de l'axe des X (22) est un capteur en pont complet référencé comprenant des premiers éléments magnétorésistifs (1) et des seconds éléments magnétorésistifs (1) possédant une réponse magnétorésistive au champ magnétique appliqué plus faible que les premiers éléments magnétorésistifs, et
    le capteur en pont de l'axe des Y (23) est un capteur en pont complet push-pull comprenant des éléments magnétorésistifs (1) avec des réponses magnétorésistives égales au champ magnétique appliqué, dans laquelle la couche piégée magnétique de direction de magnétisation (8) des éléments magnétorésistifs du capteur en pont de l'axe des X (22) et du capteur en pont de l'axe des Y (23) est identique.
     
    7. Capteur magnétorésistif à axe triple selon la revendication 6, comprenant une couche isolante (27) entre l'élément de capteur de champ magnétique à axe triple (30) et l'ASIC (19), et ladite couche isolante étant dotée de conducteurs en cuivre (28) positionnés pour réaliser un raccordement électrique entre les composants dudit élément capteur de champ magnétique à axe triple et dudit ASIC.
     
    8. Capteur magnétorésistif à axe triple selon la revendication 6, comprenant une couche isolante (27), ledit substrat étant disposé entre l'élément capteur de champ magnétique à axe triple (30) et l'ASIC (19), et
    ledit substrat étant doté de conducteurs en cuivre (28) positionnés pour réaliser un raccordement électrique entre les composants dudit élément capteur de champ magnétique à axe triple et ledit ASIC.
     
    9. Capteur magnétorésistif à axe triple selon la revendication 6, ledit capteur de l'axe des Z (24) étant une puce de capteur MTJ à anisotropie perpendiculaire possédant une surface de film positionnée sur le substrat (18) et parallèle à celui-ci, de sorte que la direction de détection du capteur de l'axe des Z soit perpendiculaire à la surface de film de la puce de capteur de l'axe des Z.
     
    10. Capteur magnétorésistif à axe triple selon la revendication 6, ledit capteur de l'axe des Z étant un capteur de champ magnétique à effet Hall ou à effet Hall géant.
     
    11. Capteur magnétorésistif à axe triple selon la revendication 6, ledit capteur de l'axe des Z (24) étant un capteur MTJ, ledit capteur de l'axe des Z comprenant des éléments magnétorésistifs MTJ (1) montés sur des surfaces inclinées opposées du substrat (18) et raccordés électriquement au substrat par des billes de soudure (26) pour former le capteur de l'axe des Z, et ledit capteur de l'axe des Z étant raccordé électriquement et physiquement à l'ASIC (19) par un conducteur en cuivre (28).
     




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    REFERENCES CITED IN THE DESCRIPTION



    This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.

    Patent documents cited in the description