CN112079327A

CN112079327A - Torque sensor and method for manufacturing the same

Info

Publication number: CN112079327A
Application number: CN202010920299.8A
Authority: CN
Inventors: 汪建平; 邓登峰
Original assignee: Hangzhou Silan Microelectronics Co Ltd
Current assignee: Hangzhou Silan Microelectronics Co Ltd
Priority date: 2020-09-04
Filing date: 2020-09-04
Publication date: 2020-12-15

Abstract

The application discloses a torque sensor and a manufacturing method thereof, comprising a substrate; an epitaxial layer on the substrate; the first doping regions and the second doping regions are respectively positioned in the epitaxial layer; a plurality of first ohmic contact regions at both ends of the first doped region; a plurality of second ohmic contact regions at both ends of the second doped region; and the first isolation structure is positioned in the epitaxial layer and the substrate and surrounds the first doped region and the second doped region. According to the torque sensor, the bending moment sensing unit is additionally arranged, the torque sensing signal and the bending moment signal are obtained at the same time, the bending moment signal is adopted to compensate the torque sensing signal, the influence of the bending moment on the torque sensing signal is eliminated, and the accuracy of the measured torque value can be improved.

Description

Torque sensor and method for manufacturing the same

Technical Field

The invention relates to the technical field of sensing, in particular to a torque sensor and a manufacturing method thereof.

Background

Torque sensors based on MEMS (Micro-Electro-Mechanical systems) are widely used, for example, a torque sensor is used in a power-assisted electric bicycle, a torque generated when a person steps on a pedal is converted into a torque through a rotating shaft of the electric bicycle, and the torque is fed back to a control motor of the electric bicycle, so as to achieve the purpose of power assistance. The principle of the piezoresistive torque sensor is that after a rotating shaft is subjected to torque, the resistance value of the sensor adhered to the rotating shaft changes, and the torque on the rotating shaft can be measured by detecting a difference signal output by a Wheatstone bridge formed by the resistance.

The MEMS piezoresistive torque sensor can be implemented by using a single crystal silicon injection resistor, and a wheatstone bridge composed of four diffusion resistors is generally used to output a differential signal to implement detection and output of a torque sensing signal. The electrical resistance in single crystal silicon not only senses longitudinal strain, i.e., strain in the direction of current flow, but also senses partial strain in the lateral and shear directions, which can produce a significant amount of cross talk in the silicon strain gauge. The bending moment is the moment required to bend the rotating shaft. In practice, the torque sensor generally uses a rod-shaped structure as shown in fig. 1 as a carrier, which not only receives a torque twisting the torque sensor along the circumferential direction of the rod, but also has a moment bending the torque sensor, i.e. a bending moment.

Disclosure of Invention

In view of the above problems, an object of the present invention is to provide a torque sensor and a method for manufacturing the same, which can eliminate the influence of bending moment, temperature, and the like on a torque sensing value output from the torque sensor and improve the accuracy of the torque sensing value output from the torque sensor.

According to a first aspect of the present invention, there is provided a torque sensor comprising: a substrate; an epitaxial layer on the substrate; the first doping regions and the second doping regions are respectively positioned in the epitaxial layer; a plurality of first ohmic contact regions at both ends of the first doped region; a plurality of second ohmic contact regions at both ends of the second doped region; the first isolation structure is positioned in the epitaxial layer and the substrate and surrounds the first doping region and the second doping region, wherein a plurality of first ohmic contact resistances are formed by the first doping regions and the first ohmic contact regions, the first ohmic contact resistances form a torque sensing unit, and a torque sensing signal is output; and a plurality of second ohmic contact resistors are formed on the second doping regions and the second ohmic contact regions, form a bending moment sensing unit and output bending moment sensing signals.

Optionally, at least four of the first ohmic contact resistances form a first wheatstone bridge configuration and at least four of the second ohmic contact resistances form a second wheatstone bridge configuration.

Optionally, the substrate is (100) crystal plane P-type silicon.

Optionally, four first ohmic contact resistors form a first wheatstone bridge structure, four second ohmic contact resistors form a second wheatstone bridge structure, and the four first ohmic contact resistors and the four second ohmic contact resistors are arranged at intervals and enclose an octagon.

Optionally, of the four first ohmic contact resistances, a first ohmic contact resistance and a second ohmic contact resistance are parallel to a [110] crystal orientation of the P-type silicon, and a third ohmic contact resistance and a fourth ohmic contact resistance are perpendicular to the [110] crystal orientation of the P-type silicon.

Optionally, in the four second ohmic contact resistors, an included angle between a first ohmic contact resistor and a second ohmic contact resistor and a [110] crystal orientation of the P-type silicon is 23 ° to 45 °, and an included angle between a third ohmic contact resistor and a fourth ohmic contact resistor and the [110] crystal orientation of the P-type silicon is 135 ° to 157 °.

Optionally, the method further comprises: and the temperature sensing unit is positioned in the epitaxial layer in the first isolation structure and used for sensing temperature change and outputting a temperature sensing signal.

Optionally, the temperature sensing unit includes: a diode or a transistor.

Optionally, the temperature sensing unit includes: the third doped region is positioned in the epitaxial layer; the third ohmic contact area is positioned in the third doping area and used as a base area of the triode; the fifth ohmic contact region is positioned in the epitaxial layer adjacent to the third doped region and is used as a collector region of the triode; and the sixth ohmic contact region is positioned in the third doped region and is used as an emitting region of the triode.

Optionally, the base and the collector of the triode are shorted.

Optionally, the method further comprises: a second isolation structure in the epitaxial layer and the substrate, the second isolation structure surrounding the temperature sensing unit.

Optionally, the first isolation structure and the second isolation structure respectively include: an upper isolation structure located in the epitaxial layer; and the lower isolation structure is positioned in the substrate and the epitaxial layer, and the upper isolation structure is connected with the lower isolation structure.

Optionally, the method further comprises: a fourth ohmic contact region in the epitaxial layer.

Optionally, the method further comprises: a plurality of buried layers located between the substrate and the epitaxial layer below the temperature sensing unit, the buried layers being partially located in the substrate.

Optionally, the method further comprises: the insulating layer is positioned on the epitaxial layer; and the plurality of conductive channels are positioned in the insulating layer, are respectively in contact with the corresponding ohmic contact regions, and are used for electrically connecting a plurality of first ohmic contact resistors of the torque sensing unit, electrically connecting a plurality of second ohmic contact resistors of the bending moment sensing unit, and electrically connecting the temperature sensing unit, the torque sensing unit and the bending moment sensing unit with the outside.

Optionally, the first ohmic contact resistance, the third ohmic contact resistance, the second ohmic contact resistance and the fourth ohmic contact resistance are sequentially connected in series through corresponding conductive channels and wires to form a closed loop, a torque sensing signal is output between a node between the first ohmic contact resistance and the third ohmic contact resistance and a node between the second ohmic contact resistance and the fourth ohmic contact resistance, and a direct current voltage is input between a node between the first ohmic contact resistance and the fourth ohmic contact resistance and a node between the second ohmic contact resistance and the third ohmic contact resistance.

Optionally, the third ohmic contact resistor, the second ohmic contact resistor, the fourth ohmic contact resistor, and the first ohmic contact resistor are sequentially connected in series through corresponding conductive channels and wires to form a closed loop, a bending moment sensing signal is output between a node between the second ohmic contact resistor and the third ohmic contact resistor and a node between the first ohmic contact resistor and the fourth ohmic contact resistor, and a direct current voltage is input between a node between the first ohmic contact resistor and the third ohmic contact resistor and a node between the second ohmic contact resistor and the fourth ohmic contact resistor.

Optionally, the upper isolation structure of the second isolation structure and the sixth ohmic contact region are connected through a conductive via and a wire, and are connected to ground.

Optionally, the method further comprises: and the bonding pads are connected with part of the conductive channels through leads and used for applying driving signals to the torque sensing unit, the bending moment sensing unit and the temperature sensing unit and outputting the torque sensing signal, the bending moment sensing signal and the temperature sensing signal.

Optionally, the substrate is a substrate deformable by torque forces and bending moment forces.

Optionally, the first doped region, the second doped region, the third doped region, the first ohmic contact region, the second ohmic contact region, and the third ohmic contact region are P-type doped regions, and the epitaxial layer, the fifth ohmic contact region, and the sixth ohmic contact region are N-type doped regions.

Optionally, the fourth ohmic contact region is an N-type doped region.

According to another aspect of the present invention, there is provided a method of manufacturing a torque sensor, including: forming an epitaxial layer on a substrate; forming a first isolation structure in the substrate and the epitaxial layer; forming a plurality of first doped regions and a plurality of second doped regions in the epitaxial layer; forming a plurality of first ohmic contact regions and a plurality of second ohmic contact regions at two ends of the first doping region and two ends of the second doping region respectively, wherein a plurality of first ohmic contact resistances are formed on the plurality of first doping regions and the first ohmic contact regions, and the plurality of first ohmic contact resistances form a torque sensing unit to output a torque sensing signal; the plurality of second doping regions and the second ohmic contact regions form a plurality of second ohmic contact resistors, the plurality of second ohmic contact resistors form a bending moment sensing unit and output bending moment sensing signals, and the first isolation structure surrounds the first doping regions and the second doping regions.

Optionally, the substrate is (100) crystal plane P-type silicon.

Optionally, the method further comprises: and forming a temperature sensing unit in the epitaxial layer in the first isolation structure, wherein the temperature sensing unit is used for sensing temperature change and outputting a temperature sensing signal.

Optionally, the temperature sensing unit includes: a diode or a transistor.

Optionally, the method further comprises: forming a third doped region in the epitaxial layer; forming a third ohmic contact region in the third doped region to serve as a base region of the triode; forming a fifth ohmic contact region in the epitaxial layer adjacent to the third doped region to serve as a collector region of the triode; and forming a sixth ohmic contact region in the third doped region to serve as an emitting region of the triode.

Optionally, the base and the collector of the triode are shorted.

Optionally, the method further comprises: forming a second isolation structure in the epitaxial layer and the substrate, the second isolation structure surrounding the temperature sensing unit.

Optionally, between the steps of forming the third ohmic contact region and forming the fifth ohmic contact region, further comprising: a fourth ohmic contact region is formed in the epitaxial layer adjacent the first doped region.

Optionally, the step of forming the first and second isolation structures comprises: forming a lower isolation structure in the substrate and the epitaxial layer; an upper isolation structure is formed in the epitaxial layer and connected with the lower isolation structure.

Optionally, between the steps of forming the lower isolation structure in the substrate and forming the epitaxial layer on the substrate, the method further includes: and forming a plurality of buried layers in the substrate, wherein the buried layers are respectively positioned between the substrate and the epitaxial layer corresponding to the torque sensing unit, the bending moment sensing unit and the temperature sensing unit, and the buried layers are partially positioned in the substrate.

Optionally, after the step of forming the first to sixth ohmic contact regions, further comprising: forming an insulating layer on the epitaxial layer; forming a plurality of vias in the insulating layer; and forming a plurality of conductive channels in the plurality of through holes, wherein the conductive channels are respectively used for electrically connecting the first ohmic contact resistors of the torque sensing unit, the second ohmic contact resistors of the bending moment sensing unit and the temperature sensing unit with the outside.

Optionally, after the step of forming a plurality of conductive vias in a plurality of the through holes, the method further includes: and forming a plurality of bonding pads, wherein the bonding pads are connected with part of the conductive channels through leads and are used for applying driving signals to the torque sensing unit, the bending moment sensing unit and the temperature sensing unit and outputting the torque sensing signals, the bending moment sensing signals and the temperature sensing signals.

Optionally, the first doped region, the second doped region, the third doped region, the first ohmic contact region, the second ohmic contact region, and the third ohmic contact region are P-type doped, and the fourth ohmic contact region, the epitaxial layer, the fifth ohmic contact region, and the sixth ohmic contact region are N-type doped regions.

The torque sensor comprises a torque sensing unit and a bending moment sensing unit, and the torque sensing unit and the bending moment sensing unit respectively output a torque sensing signal and a bending moment sensing signal and compensate the torque sensing signal according to the bending moment sensing signal to obtain a more accurate torque sensing value.

Further, the torque sensor comprises a temperature sensing unit outputting a temperature sensing signal, and the torque sensing signal can be compensated according to the temperature sensing signal, so that the accuracy of the torque sensing value is further improved.

Drawings

The above and other objects, features and advantages of the present invention will become more apparent from the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:

FIG. 1 shows a simplified installation of a torque sensing device according to the prior art;

FIG. 2 shows a schematic structural diagram of a torque sensing device according to the prior art;

FIG. 3 shows an equivalent circuit schematic of a torque sensor according to the prior art;

FIG. 4 shows a schematic structural diagram of a torque sensor according to the prior art;

FIG. 5 shows a schematic structural diagram of a torque sensor according to an embodiment of the invention;

FIG. 6 shows a schematic circuit diagram of a torque sensor according to an embodiment of the invention;

FIG. 7 illustrates a schematic structural diagram of a torque sensing device according to an embodiment of the present invention;

FIG. 8 illustrates a schematic structural diagram of a torque sensing system according to an embodiment of the present invention;

FIGS. 9 a-9 h illustrate cross-sectional views of stages of a method of manufacturing a torque sensor according to an embodiment of the invention;

fig. 10 and 11 show top views of torque sensors according to embodiments of the present invention.

Detailed Description

Various embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Like elements in the various figures are denoted by the same or similar reference numerals. For purposes of clarity, the various features in the drawings are not necessarily drawn to scale.

The following detailed description of embodiments of the present invention is provided in connection with the accompanying drawings and examples.

FIG. 1 shows a simplified installation of a torque sensing device according to the prior art. As shown in fig. 1, a prior art torque sensing device (not shown) is mounted on a rotating shaft 104 via a patch 103. The first end 101 of the rotating shaft 104 is fixed, the second end 105 is connected to a force applying part, such as a pedal, and when the pedal is in operation, the force is applied to the pedal and is transmitted through the second end 105 of the rotating shaft 104, so that the rotating shaft 104 is rotated or bent by a torque or a bending moment.

The side wall of the rotating shaft 104 has a flat surface 102, and the torque sensing device is flatly mounted on the flat surface 102, and specifically, the torque sensing device can be adhered to the flat surface 102 by using an insulating paste or a silver paste. The torque sensing device is physically limited and is generally designed as a planar structure. The planar dimension of the plane 102 is equal to or greater than the planar dimension of the torque sensing device.

Fig. 2 shows a schematic structural diagram of a torque sensing device according to the prior art. As shown in fig. 2, the torque sensing device includes a substrate 110, and a torque sensor 120 and a processing unit 130 disposed on the substrate 110, wherein the torque sensor 120 includes a plurality of torque sensing elements 1, the plurality of torque sensing elements 1 form a torque sensing unit, and the torque sensing unit senses a torque deformation of the rotating shaft 104 and outputs a torque sensing signal. The direction indicated by the arrow in fig. 2 is a clockwise direction as viewed from the second end 105 side of the rotating shaft 104. The substrate 110 may be made of an iron sheet, corresponding to 103 in fig. 1.

Referring to fig. 1 and 2, the rotation shaft 104 deforms under the action of the torque and the bending moment, the plane 102 deforms along with the rotation shaft 104, the substrate 110 deforms along with the plane 102, the torque sensitive element 1 changes the deformation to generate an electrical parameter, so as to output a corresponding torque sensing signal to the processing unit 130, and the processing unit 130 can convert the analog torque sensing signal into a digital signal for digital processing and analysis.

Fig. 3 shows an equivalent circuit schematic of the torque sensor of fig. 2. As shown in fig. 3, the torque sensor 120 includes a first wheatstone bridge structure including a first resistor R1, a second resistor R2, a third resistor R3 and a fourth resistor R4, and the first to fourth resistors (R1-R4) correspond to the torque sensing unit formed by the torque sensitive element 1 in fig. 2. The first resistor R1, the fourth resistor R4, the second resistor R2 and the third resistor R3 are connected in series to form a closed loop. A direct current voltage Vs is input between a node between the first resistor R1 and the fourth resistor R4 and a node between the second resistor R2 and the third resistor R3. A differential signal Vout, which is a torque sensing signal, is output between a node between the first resistor R1 and the third resistor R3 and a node between the second resistor R2 and the fourth resistor R4. The relation expression between the ratio of the differential signal Vout to the dc input voltage Vs and the first to fourth resistances (R1-R4) is:

fig. 4 shows a schematic diagram of the torque sensor of fig. 2. As shown in the figure, the torque sensor 120 of the prior art is a planar structure, wherein the substrate of the torque sensor 120 is a P-type silicon substrate with a (100) crystal plane, a first resistor R1, a second resistor R2, a third resistor R3 and a fourth resistor R4 are fabricated on the substrate, the placement of the resistors determines the direction of current, the placement direction of the resistors refers to the current direction of the resistors, the current direction of the first resistor R1 and the second resistor R2 is parallel to the [110] crystal direction of the P-type silicon, and the current direction of the third resistor R3 and the fourth resistor R4 is perpendicular to the current direction of the first resistor R1 and the second resistor R2, that is, perpendicular to the [110] crystal direction of the P-type silicon.

If the sensor is placed in the forward direction in the direction of fig. 4, the torque sensor 120 is placed at 45 ° in fig. 2. The [110] crystal orientation piezoresistive coefficient can be expressed as:

wherein, subscript l represents the longitudinal direction, and the corresponding stress direction is parallel to the current direction; the following table t shows the transverse direction, the direction of the corresponding stress is perpendicular to the direction of the current, and the formula of the rate of change of the resistance is combined:

the rate of change of the resistances of the first resistor R1 and the second resistor R2 is: pi₄₄Sigma/2; the rate of change of the resistances of the third resistor R3 and the fourth resistor R4 is: -pi₄₄Sigma/2. Pi is a piezoresistive coefficient, and the physical meaning of the piezoresistive coefficient is the proportional relation between the resistance change rate and the unit pressure, namely under the same pressure, the larger the piezoresistive coefficient is, the larger the resistivity change is. The unit is 1/Pa.

For (100) plane P type silicon, pi₄₄Is 1.38E-3Pa^-1. If the second end 105 of the rotating shaft 104 is subjected to clockwise force from the right end and the rotating shaft 104 is subjected to corresponding torsional force, the first resistor R1, the second resistor R2, the third resistor R3 and the fourth resistor R4 are subjected to compressive stress, the compressive stress is negative, the resistance values of the first resistor R1 and the second resistor R2 are reduced, and the resistance values of the third resistor R3 and the third resistor R4 are increased; if the second end 105 of the rotating shaft 104 receives a counterclockwise twisting force from the right end, the first resistor R1, the second resistor R2, and the second resistor R2The three resistors R3 and the third resistor R4 are under tensile stress, and the tensile stress is positive, so that the resistances of the first resistor R1 and the second resistor R2 are increased, and the resistances of the third resistor R3 and the third resistor R4 are decreased. The stress in the 45-degree angle direction is the largest, and correspondingly, the resistance changes most obviously after being stressed, so that the best measuring effect can be ensured.

If the rotating shaft 104 is subjected to bending moment force rather than torque force, referring to fig. 1, if the second end 105 of the rotating shaft 104 is subjected to downward pressure, i.e., the rotating shaft 104 is subjected to downward bending moment force, the first resistor R1, the second resistor R2, the third resistor R3 and the third resistor R4 are subjected to tensile stress, and at the same time, because the torque sensor 120 is obliquely placed at 45 °, the rate of change of the resistance of the first resistor R1 and the second resistor R2 is pi₄₄Sigma/2 multiplied by the cosine of 45 DEG, the rate of change of resistance of the third resistor R3 and the third resistor R4 is pi₄₄The product of sigma/2 and the sine of 45 degrees, namely the resistance values of the first resistor R1, the second resistor R2, the third resistor R3 and the third resistor R4 are all reduced; if the second end 105 of the rotating shaft 104 is pressed upward, i.e., the rotating shaft 104 is subjected to an upward bending moment, the first resistor R1, the second resistor R2, the third resistor R3 and the third resistor R4 are subjected to compressive stress and their resistance values are all reduced. Under the influence of bending moment force, the torque sensing signal directly output by the sensor has an error.

Fig. 5 shows a schematic structural diagram of a torque sensor according to an embodiment of the invention. Compared to the torque sensor shown in fig. 4, the torque sensor of the present embodiment includes a torque sensing unit and a bending moment sensing unit. The torque sensing unit senses a torque change of the rotating shaft 104 and outputs a torque sensing signal. The bending moment sensing unit senses bending moment deformation of the rotating shaft 104 and outputs a bending moment sensing signal.

Fig. 6 shows a schematic circuit diagram of a torque sensor according to an embodiment of the invention. As shown in fig. 6, the torque sensing unit includes a first wheatstone bridge structure including a first resistor R1, a second resistor R2, a third resistor R3, and a fourth resistor R4. The first resistor R1, the fourth resistor R4, the second resistor R2 and the third resistor R3 are connected in series to form a closed loop. A direct current voltage Vs is input between a node between the first resistor R1 and the fourth resistor R4 and a node between the second resistor R2 and the third resistor R3. A first differential signal Vout1, i.e., a torque sensing signal, is output between a node between the first resistor R1 and the third resistor R3 and a node between the second resistor R2 and the fourth resistor R4.

In the present embodiment, when there is no deformation or stress, the resistances of the first resistor R1, the second resistor R2, the third resistor R3 and the fourth resistor R4 are equal.

The current direction of the first resistor R1 and the second resistor R2 is parallel to the [110] crystal orientation direction of the P-type silicon, and the current direction of the third resistor R3 and the fourth resistor R4 is perpendicular to the current direction of the first resistor R1 and the second resistor R2, namely perpendicular to the [110] crystal orientation direction of the P-type silicon.

The bending moment sensing unit comprises a second Wheatstone bridge structure, and the second Wheatstone bridge structure comprises a fifth resistor R5, a sixth resistor R6, a seventh resistor R7 and an eighth resistor R8. The fifth resistor R5, the eighth resistor R8, the sixth resistor R6, and the seventh resistor R7 are connected in series to form a closed loop. A direct current voltage Vs is input between a node between the fifth resistor R5 and the seventh resistor R7 and a node between the sixth resistor R6 and the eighth resistor R8, and a second differential signal Vout2, i.e., a bending moment sensing signal, is output between a node between the sixth resistor R6 and the seventh resistor R7 and a node between the fifth resistor R5 and the eighth resistor R8.

In the present embodiment, when there is no deformation or stress, the resistances of the fifth resistor R5, the sixth resistor R6, the seventh resistor R7, and the eighth resistor R8 are equal.

The included angle between the current direction of the fifth resistor R5 and the sixth resistor R6 and the crystal orientation of [110] of the P-type silicon is 23-45 degrees, the current direction of the seventh resistor R7 and the eighth resistor R8 is perpendicular to the current direction of the fifth resistor R5 and the sixth resistor R6, namely, the included angle between the current direction of the seventh resistor R5 and the crystal orientation of [110] of the P-type silicon is 135-157 degrees.

In the present embodiment, the torque sensing unit and the bending moment sensing unit share the same power supply and receive the dc voltage Vs.

In a preferred embodiment, the torque sensor 202 further includes a temperature sensing unit for sensing a temperature change and outputting a temperature sensing signal.

Wherein the temperature sensing unit comprises a temperature sensitive diode D1. The temperature sensitive diode D1 is connected with a constant current source, the constant current source generates current id, and a voltage signal Vout3 at two ends of the temperature sensitive diode is the temperature sensing signal.

FIG. 7 illustrates a schematic structural diagram of a torque sensing device according to an embodiment of the present invention. As shown in fig. 7, the torque sensing device 200 includes a substrate 201, and a torque sensor 202 and a processing unit 203 provided on the substrate 201.

The torque sensor 202 is located on the substrate 201, and an included angle between the torque sensor 202 and the substrate 201 on a horizontal plane of the substrate 201 is 45 °.

The torque sensor 202 includes a torque sensing unit and a bending moment sensing unit, the torque sensing unit including a first wheatstone bridge structure including a first resistor R1, a second resistor R2, a third resistor R3, and a third resistor R4 connected in series in a closed loop; the bending moment sensing unit includes a second wheatstone bridge structure, the second wheatstone bridge structure includes a fifth resistor R5, a sixth resistor R6, a seventh resistor R7 and an eighth resistor R8 connected in series to form a closed loop, and a temperature sensitive diode D1 constituting the temperature sensing unit, where the direction indicated by the arrow in the figure is a twisting direction of the rotating shaft 104 when external force is sensed, for example, when a pedal of a moped is clockwise stepped, the rotating shaft 104 is clockwise twisted. The included angle between the current direction of the first resistor to the fourth resistor (R1-R4) of the torque sensing unit and the torque direction is 45 degrees, the current direction of the seventh resistor R7 and the eighth resistor R8 of the bending moment sensing unit is perpendicular to the torsion direction, and the fifth resistor R5 and the sixth resistor R6 are parallel to the torsion direction corresponding to the bending moment direction.

The processing unit 203 is located on the substrate 201, spaced from the torque sensor 202 and connected thereto by gold wire bonding. The processing unit 203 and the substrate 201 form an angle of 45 ° in the horizontal plane of the substrate 201. The processing unit 203 performs analog-to-digital conversion processing on the torque sensing signal and the bending moment sensing signal.

In the present embodiment, the processing unit 203 is an IC chip.

In a preferred embodiment, the processing unit 203 compensates the torque sensing signal according to the bending moment sensing signal to obtain a compensated torque sensing signal, and then performs an analog-to-digital conversion process on the compensated torque sensing signal.

The closer the distance between the processing unit 203 and the torque sensor 202 is, the better, the interference of the signal on the transmission line can be reduced, and the precision can be improved.

The installation of the torque sensor 202 shown in fig. 7 can be regarded as that the torque sensor 202 shown in fig. 5 can be rotated 45 ° counterclockwise on the horizontal plane of the substrate 201, and the processing unit 203 can also be rotated 45 ° counterclockwise on the horizontal plane of the substrate 201, so that unnecessary possible interference can be reduced. Under the condition that torque force and bending moment force exist simultaneously, the first resistor R1, the second resistor R2, the third resistor R3 and the third resistor R4 are most sensitive to torque, two resistor values are increased and reduced under the action of the torque force, a first Wheatstone bridge structure formed by the two resistor values outputs a torque sensing signal Vout1, but the resistor values can be reduced or increased by the same value under the action of the bending moment force, so that the resistance ratio relation among the first resistor R1, the second resistor R2, the third resistor R3 and the third resistor R4 can be changed, and the value of the torque sensing signal Vout1 is influenced. The sensitivity of the fifth resistor R5, the sixth resistor R6, the seventh resistor R7 and the eighth resistor R8 to bending moment is the highest, the resistance values of the two resistors are increased and reduced under the action of bending moment force, and the bending moment sensing signal Vout2 output by the second Wheatstone bridge structure formed by the two resistors is less influenced by torque. The first resistor R1, the second resistor R2, the third resistor R3 and the third resistor R4 have the same resistance value under the stress-free condition, the fifth resistor R5, the sixth resistor R6, the seventh resistor R7 and the eighth resistor R8 have the same resistance value under the stress-free condition, and some deviation exists in the actual condition without external force, and the deviation value can be initially calibrated by the processing unit.

The current directions of the fifth resistor R5 and the sixth resistor R6 form an angle of 23-45 degrees with the crystal direction of [110], the typical value is 32 degrees, the current directions of the seventh resistor R7 and the eighth resistor R8 are perpendicular to the current directions of the fifth resistor R5 and the sixth resistor R6, and form an angle of 135-157 degrees with the crystal direction of [110], the bending moment in the design direction is the largest, but the corresponding voltage dependent coefficients are also smaller, and the design can be optimized in consideration of compromise.

The temperature is an important factor which can affect the resistance value of the resistor, the temperature sensitive diode D1 is arranged on the torque sensor 202 and is used for sensing the ambient temperature, when the temperature rises, the forward voltage drop of the temperature sensitive diode D1 is reduced, for example, a constant current Id of 10 microamperes is applied to a certain temperature sensitive diode, the temperature rises by 1 ℃ every time, the forward voltage drop is reduced by 2 millivolts, and the voltage at the two ends of the temperature sensitive diode D1 is monitored to obtain a corresponding temperature value. In other embodiments, the temperature sensing unit may also be implemented by a temperature-sensitive resistor, the temperature-sensitive resistor is connected in series with the constant voltage source, and the corresponding temperature information may be obtained by detecting a current value flowing through the temperature-sensitive resistor.

The original torque sensing signal and the bending moment signal of the embodiment of the invention are voltage signals, and the original temperature sensing signal obtained by adopting the temperature sensitive diode is also a voltage signal, so that the later data processing is convenient.

FIG. 8 illustrates a schematic structural diagram of a torque sensing system according to an embodiment of the present invention. As shown in fig. 8, the torque sensing system includes a torque sensing device 200 and a micro control unit 300, wherein the torque sensing device 200 includes a torque sensor 202 and a processing unit 203, the torque sensor 202 includes a torque sensing unit 2021 and a bending moment sensing unit 2022, the torque sensing unit 2021 senses a torque output torque sensing signal of the rotating shaft, and the bending moment sensing unit 2022 senses a bending moment output bending moment sensing signal of the rotating shaft; the processing unit 203 performs analog-to-digital conversion on the torque sensing signal and the bending moment sensing signal, or compensates the torque sensing signal according to the bending moment sensing signal, and then performs analog-to-digital conversion on the compensated torque sensing signal.

In the present embodiment, the processing unit 203 is an IC chip.

The micro control unit 300 is connected to the processing unit 203 via a flexible circuit board.

When the processing unit 203 performs analog-to-digital conversion on the torque sensing signal and the bending moment sensing signal, the micro control unit 300 compensates the torque sensing signal after analog-to-digital conversion according to the bending moment sensing signal after analog-to-digital conversion, outputs a compensated torque sensing value, and eliminates the influence of the bending moment on the torque to obtain accurate torque data.

When the processing unit 203 compensates the torque sensing signal according to the bending moment sensing signal, the compensated torque sensing signal is subjected to analog-to-digital conversion processing. The micro control unit 300 receives the torque sensing signal after the analog-to-digital conversion processing, outputs a compensated torque sensing value, and eliminates the influence of the bending moment on the torque to obtain accurate torque data.

In a preferred embodiment, the torque sensor 202 further comprises a temperature sensing unit 2023, and the temperature sensing unit 2023 senses a temperature change and outputs a temperature sensing signal. The processing unit 203 compensates the torque sensing signal according to the temperature sensing signal, and then performs analog-to-digital conversion on the compensated torque sensing signal. The micro control unit 300 receives the torque sensing signal after the analog-to-digital conversion processing, outputs a compensated torque sensing value, and eliminates the influence of temperature and bending moment on the torque to obtain accurate torque data.

From the torque sensing signal, the temperature sensing signal and the bending moment sensing signal, the calibration comprises plotting a function f of different torques at different temperatures_{A button}(P_{Torsion bar}T), and then plotting the function f of different bending moments at different temperatures_{A bend}(P_BendT), then plotting the function f for different torques and bending moments at different temperatures_A(P_{Torsion bar}，P_BendT), finally, according to the relation of 3 functions, corresponding algorithm processing is carried out to eliminate the influence of temperature and bending moment, because IC processing data is not flexible enough and cost is high, and MCU (Microcontroller Unit, microcontrol Unit) is flexible, it is more beneficial for different users to adopt proper processing method according to the requirement, digital processing can be realized by MCU (Microcontroller Unit, microcontrol Unit), wherein the processing Unit can be connected with MCU by flexible circuit board. Wherein, P_{Torsion bar}＝k₁Vout1；P_Bend＝k₂Vout2, the processing unit as D/A converter converts Vout1, Vout2 and Vout3 into digital signal, and the MCU processes the digital signal data. Because the torque sensing device 200 of the embodiment of the invention has small volume and small data volume, M is adoptedThe CU is suitable. The processing unit and the MCU constitute a data processing unit, and compensate the first differential signal Vout1 using the second differential signal Vout2 and the third differential signal Vout3, and output a compensated torque sensing value.

FIGS. 9 a-9 h illustrate cross-sectional views of stages of a method of manufacturing a torque sensor, such as spliced along the cross-sectional views shown by dashed lines A1-A2 and A2-A3 in FIG. 10, in accordance with an embodiment of the present invention; fig. 10 and 11 show top views of manufacturing processes of a torque sensor according to an embodiment of the present invention, which are described in this application by taking an example that the torque sensing unit and the bending moment sensing unit respectively include four resistors, and in other embodiments, the number of resistors of the torque sensing unit and the bending moment sensing unit may be 8 or other numbers.

In the embodiment, the temperature sensing unit measures temperature according to the characteristic that a diode (P-N junction) drops forward under constant current and changes with temperature, the diode can be directly adopted, a triode (such as an NPN tube) can also be adopted, and the triode with a collector electrode and a base electrode which are in short circuit and used as a positive electrode and an emitter electrode which is used as a negative electrode is adopted as the temperature sensing unit in the embodiment.

Referring to fig. 9a, a plurality of buried layers 302 and a plurality of lower isolation doped regions 303a are formed in a substrate 301.

In this step, ion implantation is performed on the surface of the substrate 301, thereby forming a plurality of Buried layers (BN) 302. Before forming the buried layer 302, an ion implantation window is defined on the surface of the substrate 301 by photolithography, and the buried layer 302 is activated by a push junction after the ion implantation, for example, by a high temperature annealing process. In one embodiment, the buried layer 302 is located below the temperature sensing unit, and the main function of the buried layer 302 is to reduce the collector series resistance and reduce the parasitic PNP transistor amplification effect. In one embodiment, buried layer 302 is also formed below the torque sensing unit and the bending moment sensing unit.

In this embodiment, forming a plurality of lower isolation doped regions 303a in the substrate 301 is also included. The lower isolation doping region 303a is formed by ion implantation, and is P + type doped, and the implanted ions are boron (B) ions.

In this embodiment, the substrate 301 is, for example, a P-type silicon substrate of a (100) plane, the buried layer 302 is, for example, an N + -type buried layer, and the implanted ions are phosphorus ions.

Further, an epitaxial layer 304 is formed on the surface of the semiconductor structure, and ions in the lower isolation doping region 303a are diffused into the epitaxial layer 304 to form a lower isolation structure 303b, as shown in fig. 9 b.

In this embodiment, an epitaxial layer 304 is formed on the substrate 301 and the buried layer 302 by an epitaxial process. Processes for achieving epitaxial growth include Molecular Beam Epitaxy (MBE), ultra-high vacuum chemical vapor deposition (UHV/CVD), atmospheric and reduced pressure epitaxy (ATM & RP Epi), and the like. After the epitaxial layer 304 is formed, an annealing process is adopted to diffuse ions in the lower isolation doping region 303a in the epitaxial layer 304 and the substrate 301, so as to form a lower isolation structure 303b located in the substrate 301 and the epitaxial layer 304.

In this embodiment, the epitaxial layer 304 is, for example, an N-type epitaxial layer and the material is, for example, monocrystalline silicon.

Further, a plurality of upper isolation structures 305 are formed in the epitaxial layer 304, as shown in fig. 9 c.

In this embodiment, ion implantation is performed on the surface of the epitaxial layer 304 corresponding to the lower isolation structure 303b, thereby forming an upper isolation structure 305. Wherein a window for ion implantation is defined lithographically at the surface of epitaxial layer 304 prior to forming upper isolation structure 305.

In this embodiment, the upper isolation structure 305 may adopt the same photolithography mask as the lower isolation structure 303b to ensure that the upper isolation structure 305 and the lower isolation structure 303b can be connected, thereby implementing the isolation of the temperature sensing unit from the bending moment sensing unit and the torque sensing unit. The isolation structures include a first isolation structure (including an upper isolation structure 305 and a lower isolation structure 303b) and a second isolation structure (including an upper isolation structure 305 and a lower isolation structure 303b) that separates the epitaxial layer 304 into a first region and a second region in which the plurality of buried layers 302 are located, respectively. The first isolation structure surrounds the torque sensing unit, the bending moment sensing unit and the temperature sensing unit, the first isolation structure is of a square annular structure, the second isolation structure surrounds the temperature sensing unit and is of a square annular structure, the square annular structure of the second isolation structure is not closed and is provided with an opening, and a subsequently formed conductive channel is connected with the temperature sensing unit through the non-closed part of the second isolation structure.

The upper isolation structure 305 is doped P + type, for example, with boron ions implanted.

In this embodiment, the isolation structure is connected to the substrate 301 such that the temperature sensing unit is isolated from the bending moment sensing unit and the torque sensing unit on respective islands.

In this embodiment, the upper isolation structure 305 of the first isolation structure is used to prevent leakage between the epitaxial layer 304 of the first region and the lower isolation structure 303 b. Normally, to ensure that the resistances of the torque sensing unit and the bending moment sensing unit are not electrically leaked from the epitaxial layer 304, a forward voltage is applied to the epitaxial layer 304 of the first region, so that a reverse PN junction is formed between the epitaxial layer 304 and the first doped region 306a and the second doped region 306 b.

When the isolation structure and substrate 301 are connected to the torque sensor ground, the epitaxial layer 304 and substrate 301 also form an inverted PN junction so that the epitaxial layer 304 and lower isolation structure 303b do not form a via. Without the upper isolation structure 305, the reverse PN junction of the diced epitaxial layer 304 and the substrate 301 has defects in the edge region, which can lead to leakage.

Further, a plurality of first doped regions 306a, a plurality of second doped regions 306b and a third doped region 306c are formed in the epitaxial layer 304, as shown in fig. 9 d.

In this embodiment, the window for ion implantation is formed, for example, by forming a silicon nitride mask on the surface of epitaxial layer 304 and then patterning the mask. Ion implantation is performed in the epitaxial layer 304 through a patterned mask to form a plurality of first doped regions 306a, a plurality of second doped regions 306b, and a third doped region 306c, which are P-type doped.

Referring to fig. 10, the isolation structure includes a first isolation structure surrounding a first doped region 306a, a second doped region 306b and a third doped region 306c, and a second isolation structure surrounding the third doped region 306c to separate the epitaxial layer into a first region and a second region, the first doped region 306a and the second doped region 306b being located in the epitaxial layer 304 of the first region, and the third doped region 306c being located in the epitaxial layer 304 of the second region.

In this embodiment, a plurality of first doped regions 306a are used to form a plurality of resistors of the torque sensing unit, a plurality of second doped regions 306b are used to form a plurality of resistors of the bending moment sensing unit, the first doped regions 306a and the second doped regions 306b are located in the epitaxial layer 304 of the first region, the third doped regions 306c are used to form diodes of the temperature sensing unit, and the third doped regions 306c are located in the epitaxial layer 304 of the second region. In forming the first doped region 306a, the second doped region 306b and the third doped region 306c, the implanted ions are, for example, boron and gallium. In this embodiment, four first doping regions 306a and four second doping regions 306b are formed, the four first doping regions 306a and the four second doping regions 306b are arranged at intervals and surround an octagon, and the first doping regions 306a and the second doping regions 306b are isolated from each other, so that when the first doping regions 306a and the second doping regions 306b are formed, at least four ion implantation directions are provided, and the ion implantation direction of the third doping region 306c may be the same as or different from one of the four ion implantation directions.

In this embodiment, referring to fig. 10, four first doping regions 306a will subsequently form four first ohmic contact resistors, four second doping regions 306b will subsequently form four second ohmic contact resistors, and the four first ohmic contact resistors and the four second ohmic contact resistors form an octagon. Among the four first ohmic contact resistors, the first ohmic contact resistor (the first resistor R1) and the second first ohmic contact resistor (the second resistor R2) are parallel to the crystal orientation of [110] of the P-type silicon, and the third first ohmic contact resistor (the third resistor R3) and the fourth first ohmic contact resistor (the fourth resistor R4) are perpendicular to the crystal orientation of [110] of the P-type silicon. Of the four second ohmic contact resistors, an included angle between the first second ohmic contact resistor (the fifth resistor R5) and the second ohmic contact resistor (the sixth resistor R6) and the crystal orientation of [110] of the P-type silicon is 23 to 45 °, and an included angle between the third second ohmic contact resistor (the seventh resistor R7) and the fourth second ohmic contact resistor (the eighth resistor R8) and the crystal orientation of [110] of the P-type silicon is 135 to 157 °.

Further, a plurality of first ohmic contact regions 307 are formed in the first doped region 306a, a plurality of second ohmic contact regions 318 are formed in the second doped region 306b and a third ohmic contact region 308 is formed in the third doped region 306c, as shown in fig. 9 e.

In this embodiment, a first ohmic contact region 307 is formed at both ends of the first doped region 306a, a second ohmic contact region 318 is formed at both ends of the second doped region 306b, and a third ohmic contact region 308 is formed in the third doped region 306c by ion implantation, and the first ohmic contact region 307, the second ohmic contact region 318 and the third ohmic contact region 308 are all P-type doped regions. The ion doping concentration of the first, second and third

ohmic contact regions

307, 318 and 308 is higher than that of the first, second and third

doped regions

306a, 306b and 306 c.

In this embodiment, the first ohmic contact region 307 and the first doped region 306a form first to fourth first ohmic contact resistances for constituting the torque sensing unit, corresponding to the resistances R1-R4 in fig. 7, and the second ohmic contact region 318 and the second doped region 306b form first to fourth second ohmic contact resistances for constituting the bending moment sensing unit, corresponding to the resistances R5-R8 in fig. 7, the first ohmic contact region 307 serves as an electrode region of the first ohmic contact resistance, the second ohmic contact region 318 serves as an electrode region of the second ohmic contact resistance, which electrode regions are used for subsequent electrical connections, thereby forming the resistances in the torque sensing unit and the bending moment sensing unit. The third ohmic contact region 308 is located in the third doped region 306c and serves as a base of the temperature sensing unit, in this embodiment, a transistor with a shorted base and collector is used as the temperature sensing unit, and in other embodiments, a diode may be directly used.

Further, a fourth ohmic contact region 309, a fifth ohmic contact region 310 are formed in the epitaxial layer 304 and a sixth ohmic contact region 311 is formed in the third doped region 306c, as shown in fig. 9f and 10.

In this embodiment, an ion implantation process is used to form the fourth ohmic contact region 309, the fifth ohmic contact region 310, and the sixth ohmic contact region 311, and the fourth ohmic contact region 309, the fifth ohmic contact region 310, and the sixth ohmic contact region 311 are all N + type doped regions.

In this embodiment, the fourth ohmic contact region 309 is located in the epitaxial layer 304 of the first region, and then a high level is applied to the epitaxial layer 304 of the first region through the fourth ohmic contact region 309, so as to avoid a forward leakage between the first and second

doped regions

306a and 306b and the epitaxial layer 304.

The fifth ohmic contact region 310 is located in the epitaxial layer 304 of the second region and serves as a collector of the transistor of the temperature sensing unit, and the sixth ohmic contact region 311 is located in the third doped region 306c and serves as an emitter of the transistor of the temperature sensing unit.

Further, an insulating layer 312 is formed on the surface of the semiconductor structure, and a plurality of via holes 313 are formed in the insulating layer 312, as shown in fig. 9 g.

In this step, an insulating layer 312 is formed on the surface of the semiconductor structure using a physical vapor deposition or chemical vapor deposition process. The insulating layer 312 is made of, for example, Boro-phospho-silicate Glass (BPSG), which is silicon dioxide doped with boron and phosphorus, and has an excellent hole filling capability, so that the surface of the epitaxial layer 304 can be planarized.

In this embodiment, the method further includes forming a plurality of via holes 313 in the insulating layer 312, for example, forming a photoresist mask on a surface of the insulating layer 313, and then performing anisotropic etching. Anisotropic etching employs, for example, dry etching such as ion milling etching, plasma etching, reactive ion etching, laser ablation, or the like. In forming the via 313, the epitaxial layer 304 is used as an etching stop layer, for example, or etching is stopped at the surface of the epitaxial layer 304 by controlling the etching time.

In this embodiment, the plurality of through holes 313 are respectively located in the insulating layer 312 above the ohmic contact regions (including the first to sixth ohmic contact regions 307 to 311), and the bottom of the through holes 313 expose the corresponding ohmic contact regions, so that the subsequently formed conductive channels can contact the corresponding positions of the torque sensing unit (the plurality of first ohmic contact resistances) and the bending moment sensing unit (the plurality of second ohmic contact resistances) to realize electrical connection.

Further, a conductive material is filled in the plurality of via holes 313 to form a plurality of conductive vias 314, as shown in fig. 9 h.

In this embodiment, a plurality of conductive vias 314 are formed in the plurality of vias 313, for example, using an atomic layer deposition, physical vapor deposition, or chemical vapor deposition process. The material of the conductive path 314 is, for example, a metal conductive material. The conductive via 314 also includes a portion formed at the surface of the insulating layer 312 via a press point.

In this embodiment, the conductive via 314 above the third ohmic contact region 308 and the fifth ohmic contact region 310 is connected because the collector and base of the transistor are shorted, thereby forming a diode.

Further, forming a wiring layer on the insulating layer 312 is also included, as shown in fig. 11.

In this embodiment, the first isolation structure surrounding the first doped region 306a, the second doped region 306b and the third doped region 306c is not shown. Referring to fig. 11, the wiring layer includes a first wire 315 connecting a plurality of first ohmic contact resistances in the torque sensing unit and a second wire 316 connecting a plurality of second ohmic contact resistances in the bending moment sensing unit, and the trio of the temperature sensing unit is connected by the second wire 316.

The first lead 315 sequentially connects the plurality of first ohmic contact resistors in series through conductive paths of the plurality of first ohmic contact resistors, and leads out a connection terminal of the torque sensing unit through the second lead 316 for external connection; the second wire 316 sequentially connects the plurality of second ohmic contact resistors in series through conductive paths of the plurality of second ohmic contact resistors, and leads out a connection terminal of the torque sensing unit for external connection.

In this embodiment, the first and

second conductors

315, 316 are located, for example, in different layers, separated by an insulating layer, the torque sensing unit and the bending moment sensing unit share the same power source, there is a common connection point where the first and

second conductors

315, 316 are connected by a conductive channel 314.

In this embodiment, referring to fig. 6 and 11, when viewed in a counterclockwise direction, the first ohmic contact resistor (first resistor R1), the fourth first ohmic contact resistor (fourth resistor R4), the second first ohmic contact resistor (second resistor R2), and the third first ohmic contact resistor (third resistor R3) are sequentially connected in series through the corresponding conductive channels and conductive wires to form a closed loop, a torque sensing signal is output between a node between the first ohmic contact resistor (first resistor R1) and the third first ohmic contact resistor (third resistor R3) and a node between the second ohmic contact resistor (second resistor R2) and the fourth first ohmic contact resistor (fourth resistor R4), and a node between the first ohmic contact resistor (first resistor R1) and the fourth ohmic contact resistor (fourth resistor R4) and the second ohmic contact resistor (second resistor R2) and the third ohmic contact resistor (third resistor R3) are sequentially connected in series, and the torque sensing signal is output between the node between the first ohmic contact resistor R1 and the fourth ohmic contact resistor R4 A direct current voltage is input between the nodes.

A third second ohmic contact resistor (a seventh resistor R7), a first second ohmic contact resistor (a fifth resistor R5), a fourth second ohmic contact resistor (an eighth resistor R8) and a second ohmic contact resistor (a sixth resistor R6) are sequentially connected in series through corresponding conductive channels and wires to form a closed loop, a bending moment sensing signal is output between a node between the second ohmic contact resistor (the sixth resistor R6) and the third second ohmic contact resistor (the seventh resistor R7) and a node between the first second ohmic contact resistor (the fifth resistor R5) and the fourth second ohmic contact resistor (the eighth resistor R8), a direct-current voltage is input between a node between the first second ohmic contact resistor (the fifth resistor R5) and the third second ohmic contact resistor (the seventh resistor R7) and a node between the second ohmic contact resistor (the sixth resistor R6) and the fourth second ohmic contact resistor (the eighth resistor R8).

Further, a plurality of bonding pads 317 are formed, the bonding pads 317 are connected with the second conducting wire 316 and located at the end of the second conducting wire 316, and power signals are applied to the torque sensor through the bonding pads 317 and output signals are obtained.

In this embodiment, the plurality of pads 317 include VS pads, GND pads, Vout1+ pads and Vout 1-pads, Vout2+ pads and Vout 2-pads, and Vout3+ pads, wherein a direct current voltage is applied to the torque sensing unit and the bending moment sensing unit through the VS pads and the GND pads, a torque sensing signal output from the torque sensing unit is obtained through the Vout1+ pads and the Vout 1-pads, a bending moment sensing signal output from the bending moment sensing unit is obtained through the Vout2+ pads and the Vout 2-pads, and a temperature sensing signal output from the temperature sensing unit is obtained through the Vout3+ pads and the GND pads.

In the final semiconductor device, the isolation structure is connected to the GND pad for connection to ground.

The torque sensor comprises a torque sensing unit highly sensitive to torque and a bending moment sensing unit highly sensitive to bending moment, can provide a torque sensing signal and a bending moment sensing signal at the same time, can compensate the torque sensing signal according to the bending moment sensing signal, and provides a more accurate torque sensing value.

The torque sensing device is provided with the torque sensing unit and the bending moment sensing unit, and processes the torque data and the bending moment data, so that the influence of the bending moment on the torque can be eliminated, and the torque sensing device is ensured to output accurate torque data. The torque sensor also comprises a temperature sensing unit which is used for measuring the influence of temperature on a torque sensitive device of the torque sensing unit so as to eliminate the influence of the temperature on the detection result of the torque sensor and further improve the accuracy of the torque data of the torque sensing device. The MCU can be adopted to ensure the data processing precision at low cost.

While embodiments in accordance with the invention have been described above, these embodiments are not intended to be exhaustive or to limit the invention to the precise embodiments described. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and the practical application, to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A torque sensor, comprising:

a substrate;

an epitaxial layer on the substrate;

the first doping regions and the second doping regions are respectively positioned in the epitaxial layer;

a plurality of first ohmic contact regions at both ends of the first doped region;

a plurality of second ohmic contact regions at both ends of the second doped region; and

a first isolation structure in the epitaxial layer and the substrate surrounding the first doped region and the second doped region,

the first doping regions and the first ohmic contact regions form a plurality of first ohmic contact resistances, the first ohmic contact resistances form a torque sensing unit, and a torque sensing signal is output; and a plurality of second ohmic contact resistors are formed on the second doping regions and the second ohmic contact regions, form a bending moment sensing unit and output bending moment sensing signals.

2. The torque transducer according to claim 1, wherein at least four of the first ohmic contact resistances form a first wheatstone bridge configuration and at least four of the second ohmic contact resistances form a second wheatstone bridge configuration.

3. The torque transducer according to claim 2, wherein the substrate is (100) plane P-type silicon.

4. The torque transducer according to claim 3, wherein four of the first ohmic contact resistors form a first Wheatstone bridge configuration and four of the second ohmic contact resistors form a second Wheatstone bridge configuration, the four first ohmic contact resistors and the four second ohmic contact resistors being spaced apart and enclosing an octagon.

5. The torque sensor according to claim 4, wherein of the four first ohmic contact resistances, a first and a second of the first ohmic contact resistances are parallel to a [110] crystal orientation of the P-type silicon, and a third and a fourth of the first ohmic contact resistances are perpendicular to the [110] crystal orientation of the P-type silicon.

6. The torque sensor according to claim 5, wherein, of the four second ohmic contact resistances, an included angle between a first ohmic contact resistance and a second ohmic contact resistance and a [110] crystal orientation of the P-type silicon is 23-45 °, and an included angle between a third ohmic contact resistance and a fourth ohmic contact resistance and the [110] crystal orientation of the P-type silicon is 135-157 °.

7. The torque sensor of claim 4, further comprising:

and the temperature sensing unit is positioned in the epitaxial layer in the first isolation structure and used for sensing temperature change and outputting a temperature sensing signal.

8. The torque sensor according to claim 7, wherein the temperature sensing unit includes: a diode or a transistor.

9. The torque sensor according to claim 8, wherein the temperature sensing unit includes:

the third doped region is positioned in the epitaxial layer;

the third ohmic contact area is positioned in the third doping area and used as a base area of the triode;

the fifth ohmic contact region is positioned in the epitaxial layer adjacent to the third doped region and is used as a collector region of the triode;

and the sixth ohmic contact region is positioned in the third doped region and is used as an emitting region of the triode.

10. The torque transducer according to claim 9, wherein the base and collector of the transistor are shorted.

11. The torque sensor of claim 10, further comprising:

a second isolation structure in the epitaxial layer and the substrate, the second isolation structure surrounding the temperature sensing unit.

12. The torque sensor of claim 11, wherein the first and second isolation structures each comprise:

an upper isolation structure located in the epitaxial layer;

and the lower isolation structure is positioned in the substrate and the epitaxial layer, and the upper isolation structure is connected with the lower isolation structure.

13. The torque sensor of claim 1, further comprising:

a fourth ohmic contact region in the epitaxial layer.

14. The torque sensor of claim 7, further comprising:

a plurality of buried layers located between the substrate and the epitaxial layer below the temperature sensing unit, the buried layers being partially located in the substrate.

15. The torque sensor of claim 7, further comprising:

the insulating layer is positioned on the epitaxial layer;

and the plurality of conductive channels are positioned in the insulating layer, are respectively in contact with the corresponding ohmic contact regions, and are used for electrically connecting a plurality of first ohmic contact resistors of the torque sensing unit, electrically connecting a plurality of second ohmic contact resistors of the bending moment sensing unit, and electrically connecting the temperature sensing unit, the torque sensing unit and the bending moment sensing unit with the outside.

16. The torque transducer according to claim 15, wherein a first ohmic contact resistor, a fourth ohmic contact resistor, a second ohmic contact resistor and a third ohmic contact resistor are connected in series via respective conductive paths and conductive lines to form a closed loop, a torque sensing signal is output between a node between the first ohmic contact resistor and the third ohmic contact resistor and a node between the second ohmic contact resistor and the fourth ohmic contact resistor, and a dc voltage is input between the node between the first ohmic contact resistor and the fourth ohmic contact resistor and a node between the second ohmic contact resistor and the third ohmic contact resistor.

17. The torque transducer according to claim 15, wherein a third ohmic contact resistor, a first ohmic contact resistor, a fourth ohmic contact resistor, and a second ohmic contact resistor are connected in series via respective conductive paths and conductive lines to form a closed loop, a bending moment sensing signal is output between a node between the second ohmic contact resistor and the third ohmic contact resistor and a node between the first ohmic contact resistor and the fourth ohmic contact resistor, and a dc voltage is input between the node between the first ohmic contact resistor and the third ohmic contact resistor and a node between the second ohmic contact resistor and the fourth ohmic contact resistor.

18. The torque transducer according to claim 12, wherein the upper isolation structure of the second isolation structure is connected to the sixth ohmic contact region by a conductive via and wire and to ground.

19. The torque sensor according to claim 16 or 17, further comprising:

and the bonding pads are connected with part of the conductive channels through leads and used for applying driving signals to the torque sensing unit, the bending moment sensing unit and the temperature sensing unit and outputting the torque sensing signal, the bending moment sensing signal and the temperature sensing signal.

20. The torque sensor of claim 3, wherein the substrate is a substrate deformable by torque forces and bending moment forces.

21. The torque transducer according to claim 9, wherein the first, second, third, first, second and third ohmic contact regions are P-type doped, and the epitaxial layer, the fifth and sixth ohmic contact regions are N-type doped.

22. The torque sensor of claim 13, wherein the fourth ohmic contact region is an N-type doped region.

23. A method of manufacturing a torque sensor, comprising:

forming an epitaxial layer on a substrate;

forming a first isolation structure in the substrate and the epitaxial layer;

forming a plurality of first doped regions and a plurality of second doped regions in the epitaxial layer; and

a plurality of first ohmic contact regions and a plurality of second ohmic contact regions are formed at both ends of the first doping region and both ends of the second doping region, respectively,

the first doping regions and the first ohmic contact regions form a plurality of first ohmic contact resistances, the first ohmic contact resistances form a torque sensing unit, and a torque sensing signal is output; the plurality of second doping regions and the second ohmic contact regions form a plurality of second ohmic contact resistors, the plurality of second ohmic contact resistors form a bending moment sensing unit and output bending moment sensing signals, and the first isolation structure surrounds the first doping regions and the second doping regions.

24. The method of manufacturing as claimed in claim 23, wherein at least four of the first ohmic contact resistances form a first wheatstone bridge configuration and at least four of the second ohmic contact resistances form a second wheatstone bridge configuration.

25. The manufacturing method according to claim 24, wherein the substrate is (100) plane P-type silicon.

26. The manufacturing method according to claim 25, wherein four first ohmic contact resistors constitute a first wheatstone bridge configuration, four second ohmic contact resistors constitute a second wheatstone bridge configuration, and four first ohmic contact resistors and four second ohmic contact resistors are arranged at intervals and surround an octagon.

27. The method of manufacturing of claim 26, wherein a first and a second of the four first ohmic contact resistances are parallel to a [110] crystal orientation of the P-type silicon, and a third and a fourth of the first ohmic contact resistances are perpendicular to the [110] crystal orientation of the P-type silicon.

28. The manufacturing method according to claim 27,

among the four second ohmic contact resistors, an included angle between the first ohmic contact resistor and the P-type silicon in the crystal orientation [110] is 23-45 degrees, and an included angle between the third ohmic contact resistor and the P-type silicon in the crystal orientation [110] is 135-157 degrees.

29. The method of manufacturing of claim 26, further comprising:

and forming a temperature sensing unit in the epitaxial layer in the first isolation structure, wherein the temperature sensing unit is used for sensing temperature change and outputting a temperature sensing signal.

30. The manufacturing method of claim 29, wherein the temperature sensing unit comprises: a diode or a transistor.

31. The method of manufacturing of claim 30, further comprising:

forming a third doped region in the epitaxial layer;

forming a third ohmic contact region in the third doped region to serve as a base region of the triode;

forming a fifth ohmic contact region in the epitaxial layer adjacent to the third doped region to serve as a collector region of the triode;

and forming a sixth ohmic contact region in the third doped region to serve as an emitting region of the triode.

32. The method of manufacturing of claim 31, wherein the base and collector of the transistor are shorted.

33. The method of manufacturing of claim 29, further comprising:

forming a second isolation structure in the epitaxial layer and the substrate, the second isolation structure surrounding the temperature sensing unit.

34. A method of manufacturing as claimed in claim 31, wherein, between the steps of forming the third ohmic contact region and forming the fifth ohmic contact region, further comprising:

a fourth ohmic contact region is formed in the epitaxial layer adjacent the first doped region.

35. The method of manufacturing of claim 23, wherein the substrate is a substrate deformable by torque forces and bending moment forces.

36. The method of manufacturing of claim 33, wherein forming the first and second isolation structures comprises:

forming a lower isolation structure in the substrate and the epitaxial layer;

an upper isolation structure is formed in the epitaxial layer and connected with the lower isolation structure.

37. The method of manufacturing of claim 36, wherein between the steps of forming a lower isolation structure in a substrate and forming an epitaxial layer on the substrate, further comprising:

and forming a plurality of buried layers in the substrate, wherein the buried layers are respectively positioned between the substrate and the epitaxial layer corresponding to the torque sensing unit, the bending moment sensing unit and the temperature sensing unit, and the buried layers are partially positioned in the substrate.

38. The manufacturing method according to claim 34, further comprising, after the step of forming the first to sixth ohmic contact regions:

forming an insulating layer on the epitaxial layer;

forming a plurality of vias in the insulating layer;

and forming a plurality of conductive channels in the plurality of through holes, wherein the conductive channels are respectively used for electrically connecting the first ohmic contact resistors of the torque sensing unit, the second ohmic contact resistors of the bending moment sensing unit and the temperature sensing unit with the outside.

39. The manufacturing method according to claim 38, wherein a first ohmic contact resistor, a fourth ohmic contact resistor, a second ohmic contact resistor, and a third ohmic contact resistor are connected in series in sequence via respective conductive paths and wires to form a closed loop, a torque sensing signal is output between a node between the first ohmic contact resistor and the third ohmic contact resistor and a node between the second ohmic contact resistor and the fourth ohmic contact resistor, and a direct current voltage is input between the node between the first ohmic contact resistor and the fourth ohmic contact resistor and a node between the second ohmic contact resistor and the third ohmic contact resistor.

40. The manufacturing method according to claim 38, wherein a third ohmic contact resistor, a first ohmic contact resistor, a fourth ohmic contact resistor and a second ohmic contact resistor are connected in series via respective conductive paths and conductive wires to form a closed loop, a bending moment sensing signal is output between a node between the second ohmic contact resistor and the third ohmic contact resistor and a node between the first ohmic contact resistor and the fourth ohmic contact resistor, and a direct current voltage is input between a node between the first ohmic contact resistor and the third ohmic contact resistor and a node between the second ohmic contact resistor and the fourth ohmic contact resistor.

41. The method of manufacturing of claim 38, wherein after the step of forming a plurality of conductive vias in the plurality of vias, further comprising:

and forming a plurality of bonding pads, wherein the bonding pads are connected with part of the conductive channels through leads and are used for applying driving signals to the torque sensing unit, the bending moment sensing unit and the temperature sensing unit and outputting the torque sensing signals, the bending moment sensing signals and the temperature sensing signals.

42. The method of manufacturing of claim 34, wherein the first, second, third, first, second, and third ohmic contact regions are P-type doped, and the fourth, epitaxial, fifth, and sixth ohmic contact regions are N-type doped.