BG112694A - Integrated two-axis magnetic field sensor - Google Patents

Abstract

The two-axis integrated magnetic field sensor contains a semiconductor substrate (1) with p-type impurity conductivity, on one side of which are formed two identical structures of the same semiconductor, but with n-type impurity conductivity and in the form of an equilateral cross - first ) and a second (3), parallel to each other. Each of the structures (2 and 3) contains one more central ohmic contact (4 and 5) with a square shape, and symmetrically to its four sides there is one external rectangular ohmic contact - clockwise first (6 and 7), second (8 and (9), third (10 and 11), and fourth (12 and 13) Contacts (4 and 5) are connected to the terminals of the current source (14). The contact (6) of the first structure (2) is connected with the contact (11) of the second structure (3), the contact (8) of the structure (2) is connected to the contact (13) of the second structure (3), the contact (10) of the structure (2) is connected to the contact (7) ) of the second structure (3), and the contact (12) of the structure (2) is connected to the contact (9) of the second structure (3) .The measured magnetic field (15) is in the plane of the substrate (1) and is of arbitrary The contacts (6 and 10) of the structure (2) are the differential output (16) for one orthogonal planar component of the magnetic field (15), and the contacts (9 and 13) of the structure (3) are the differential output (17) for the other orthogonal plane component of the magnetic field (15).

Description

TWO-AXLE INTEGRATED MAGNETIC FIELD SENSOR

FIELD OF THE INVENTION

The invention relates to a two-axis integrated magnetic field sensor applicable in the field of robotics and mechatronics; control and measurement technology; low-field magnetometry; navigation; automation, including contactless automation; micro- and nanotechnologies; 2-D positioning of objects in the plane; energy; the automotive industry, including the electric car industry; remote measurement of angular and linear displacements; biomedical research; military and security, including underwater, ground and air surveillance and prevention systems; counterterrorism, etc. , · *

BACKGROUND OF THE INVENTION

A two-axis integrated magnetic field sensor is known, containing a n-type semiconductor structure (silicon), on one side of which a central ohmic contact with a square shape is formed. At distances and symmetrically with respect to its four sides, there is one rectangular inner ohmic contact and one rectangular outer ohmic contact. The four external contacts are connected and connected to the central contact via a power source. The measured magnetic field is in the plane of the structure and has an arbitrary orientation as each pair opposite to the central internal contacts are the outputs for the two orthogonal planar components of the magnetic field, [1-3].

The disadvantage of this biaxial integrated magnetic field sensor is the reduced sensitivity of the two outputs from surface leakage of the four supply current components between the central and end contacts, leading to incomplete generation of the respective running voltages forming the metrological information of the two sensor channels.

Another disadvantage is the low measurement accuracy as a result of the parasitic mutual interchannel influence in the process of measuring the two orthogonal magnetic components.

TECHNICAL ESSENCE

It is an object of the invention to provide a two-axis integrated magnetic field sensor with high sensitivity and high measuring accuracy of the two sensor channels.

This problem is solved with a two-axis integrated magnetic field sensor containing a semiconductor substrate with p-type impurity conductivity, on one side of which are formed two identical structures of the same semiconductor, but with p-type impurity conductivity and in the form of an equilateral cross - first and second, parallel to each other. Each of the l-type structures contains another central ohmic contact with a square shape and symmetrically to its four sides there is an external rectangular ohmic contact - clockwise first, second, third and fourth, respectively. The two square contacts are connected to the terminals of a power source. The first contact of the first structure is connected to the third contact of the second, the second contact of the first structure is connected to the fourth contact of the second, the third contact of the first structure is connected to the first contact of the second, and the fourth contact of the first structure is connected to the second contact. from the second. The measured magnetic field is in the plane of the p-type substrate and is of arbitrary orientation as the first and third contacts of the first structure are the differential output for one orthogonal plane component of the magnetic field, and the second and fourth contacts of the second structure are the differential output for the other orthogonal plane component of the magnetic field.

An advantage of the invention is the high magnetic sensitivity of the two sensor outputs due to the generation by the four components of the supply currents in each of the two structures of the full Hall voltages as a result of the neutralized surface current flow in the two structures.

Another advantage is the high measuring accuracy of the two sensor channels, as there is no mutual channel influence as a result of the well-localized parts of the supply currents in the two cruciform structures generating Hall voltages only from the respective orthogonal components of the magnetic field in the substrate plane.

Another advantage is the significantly reduced parasitic voltage of the two outputs in the absence of a magnetic field (offsets), due to the original connection of the respective end contacts of the two structures, which leads to averaging of possible negative signals related to geometric and technological imperfections. .

DESCRIPTION OF THE ATTACHED FIGURES

The invention is illustrated in more detail by an exemplary embodiment thereof, given in the attached Figure 1.

EXAMPLES OF IMPLEMENTATION

The biaxial integrated magnetic field sensor contains a semiconductor substrate 1 with p-type impurity conductivity, on one side of which are formed two identical structures of the same semiconductor, but with p-type impurity conductivity and in the form of an equilateral cross - first 2 and second 3 , parallel to each other. Each of the structures 2 and 3 contains another central ohmic contact 4 and 5 with a square shape and symmetrically to its four sides there is an external rectangular ohmic contact - clockwise first 6 and 7, second 8 and 9, third 10 and 11, and fourths 12 and 13. The two contacts 4 and 5 are connected to the terminals of the current source 14. The first contact 6 of the first structure 2 is connected to the third contact 11 of the second 3, the second contact 8 of the first structure 2 is connected to the fourth contact 13 of the second 3, the third contact 10 of the first structure 2 is connected to the first contact 7 of the second 3, and the fourth contact 12 of the first structure 2 is connected to the second contact 9 of the second 3. The measured magnetic field 15 is in the plane p- type substrate 1 and has an arbitrary orientation as the first 6 and the third contact 10 of the first structure 2 are the differential output 16 for one orthogonal planar component of the magnetic field 15, and the second 9 and the fourth contact 13 of the second structure 3 are the differential output 17 for the other orthogonal plane component of the magnetic field 15.

The operation of the biaxial integrated magnetic field sensor according to the invention is as follows. When the central contacts 4 and 5 of the two identical cross-shaped structures 2 and 3 are connected to the current source 14 and the connections between the end contacts 6 - 11, 8 - 13, 10 - 7 and 12 - 9 are made in this way, four identical components flow = / 4,10 = A, 8 = Ldg = / 5,7 = D, n = ^ 5,9 = / 5,13 of the total supply current / _{4> 5} . Given the connection of the ohmic contacts 6 11, 8 - 13, 10 - 7 and 12 - 9, the current components are directed in the opposite direction: / 4,6 = - / 4,10; A, 8 = - A, 12; ^ 5,7 = - / 5,11 ^and ^ 5,9 = - / 5,13 · The technological integral realization of the two i-type structures 2 and 3 in the form of an equilateral cross on the p-substrate 1 provides from. on the one hand, their electrical insulation, preventing parasitic influence between them, and on the other - completely limited flow of current components in the cross-shaped structures 2 and 3. Also removes the surface leakage of the supply current of the sensor, leading to many negative consequences, such as in the known solution. The selected connection of contacts 6 - 11, 8-13, 10 - 7 and 12 - 9 significantly reduces the inevitable parasitic voltage at the two outputs 16 and 17 in the absence of magnetic field B 15 (offsets). The reason for this advantage of the solution of Figure 1 is the averaging and minimization of possible parasitic signals resulting from geometric and technological imperfections violating the electrical symmetry in structures 2 and 3. An important result is that the two sensor subsystems 2 and 3 operate in generator mode. current. This is achieved by their series connection to the current source 14 - the internal ohmic resistances of the respective sides of the two cross-shaped structures 2 and 3 are summed, providing a constant value of the current components / _{4; 6} = / _{4> 10} = L, 8 = h, n = /5.7 = / _{5) 11} = / 5,9 = / 5,13 · That is why the metrological information of the two outputs 16 and 17 of the sensor is a voltage format and is convenient for further processing. The trajectory of the eight current components of the current / 4,5 in the areas under contacts 4, 6, 8, 10 and 12 for structure 2, and respectively 5, 7, 9, 11, 13 for structure 3 is initially perpendicular to their upper surfaces, since these contacts are low-impedance and represent equipotential planes. The current lines penetrate the volume of structures 2 and 3, after which their effective trajectories are parallel to the upper surfaces.

The external magnetic field B 15, which is in the plane x-y of the substrate 1 and has an arbitrary orientation, through its two mutually perpendicular components B _x and B _y leads to the emergence of corresponding deflecting moving carriers in the current components Lorentz forces, F _{L > i} = gV _dr х В, where q is the elementary load of the electron, and V _dr is the vector of the average drift velocity of the electrons. Since all current components are limited in the countries of the cruciform structures 2 and 3, the action of the Lorentz forces F [is maximally effective. As a result of the Lorentz deflection F [the trajectories of the oppositely directed current components = - Hello; D.8 = - 412; / 5,7 = - Дп И 1 ₅ , ₉ = - А, 13 "shrink" and respectively "expand". Depending on the direction of the magnetic vector B (B _X , B ^ 15, each in the pairs of opposite currents increases or decreases at the expense of the other. This sensory mechanism is a manifestation of the well-known Hall effect [1,3]. current generator operation, instead of changes of the individual current components through the ohmic contacts of the two structures 2 and 3, on these terminals opposite in sign Hall potentials are generated.These potentials form in the differential outputs 16 and 17 Hall voltages Vn / B) and UDV ), which are the information indicators for the two orthogonal components B _x and B _y of the magnetic field vector B 15. The connection of contacts 6-11, 8 - 13, 10 - 7 and 12-9 provides parallel connection of Hall potentials with one and same sign. The output voltages Y1b (B) and Vi7 (B) are linear and odd functions of the magnetic fields B _x and B _y . The increase in magnetosensitivity is due to the current limiting components of the current / 4,5 through the cross-shaped zones. This innovative approach eliminates the flow of currents in the near-surface areas, improving the orthogonality of the respective current components relative to the two planar vectors B _x and B _y of the magnetic field B 15. Thus the force F] acts most effectively on the whole component, generating maximum Hall potential on the surface. In addition, the magnetically controlled surface current i _s additionally achieves a higher conversion efficiency [4]. The limited current components in the cross-shaped regions of structures 2 and 3 eliminate one of the significant disadvantages of vector magnetometry - the mutual interchannel influence when measuring the magnetic fields B _x and B _y . The absolute value of the vector of the magnetic field B 15 in the plane x-y and the angle Θ of the field B 15 relative to a fixed reference axis in the same plane are given by the expressions: | = (B _x + B _y ² ) ^1/2 and Θ = 1ap ^l (Y _y {B _y ) 1Y _x {VD), [1,3].

The unexpected positive effect of the new technical solution lies in the originality of the selected cruciform structure, limiting the surface current flow. In addition, the configuration and innovative connection of contacts 6-11, 8-13,

- 7 and 12 - 9 leads to simultaneous increase of the magnetic sensitivity, the accuracy of the 2-D sensor and elimination of the parasitic interchannel influence.

The two-axis magnetic field sensor can be realized with various modifications of the integrated silicon technology - CMOS, BiCMOS, SOS, and if necessary, micromachining silicon processes can be used. In addition to the integrated design, the two-axis microsensor for magnetic field allows, if necessary, a discrete implementation. The new 2-D magnetometer also functions in the field of cryogenic temperatures, which increases the sensitivity of both channels, especially for the purposes of low-field magnetometry and counterterrorism.

APPENDIX: one figure

LITERATURE

[1] Ch.S. Roumenin, Microsensors for magnetic field, in “MEMS - a practical guide to design, analysis and applications”, Ch. 9, ed. by J. Korvink and O. Paul, William Andrew Publ., USA, 2006, pp. 453-523; ISBN: 0-8155-1497-2.

[2] R. Popovic, Hall effect devices, 2 ^nd ed., Ser. The Adam Hilger series on sensors, Bristol, IOP Publ. Ltd, 2004.

[3] C. Roumenin, “Solid State Magnetic Sensors” - Handbook of Sensors and Actuators, Elsevier, Amsterdam-Lausanne-New York-OxfordShannon-Tokyo, 1994, pp. 450; ISBN: 0 444 89401.

[4] C. Roumenin, S. Lozanova, S. Noykov, Experimental evidence of magnetically controlled surface current in Hall devices, Sensors and Actuators, A 175, (2012) 45-52.

Claims (1)

PATENT CLAIMS Biaxial integrated magnetic field sensor, containing a semiconductor structure with p-type impurity conductivity, on which are formed a central ohmic contact with a square shape and symmetrically to its four sides on one external rectangular ohmic contact - clockwise respectively first, second, third and fourth, there is a current source as the measured magnetic field is in the plane of the structure and is of arbitrary orientation, CHARACTERIZED by the fact that there is a second semiconductor structure (3) with n-type impurity conductivity, identical to the first (2) as the two are in the shape of an equilateral cross and are parallel to each other, in the same way on both the first structure (2) and on the second (3) are also formed a central square and ohmic contact (5) and symmetrically to its four sides there are one external rectangular ohmic contact - clockwise respectively first (7), second (9), third (11) and fourth (13), structures (2) and (3) are located on a semiconductor pad (1) of the same semiconductor, but with p-type impurity conductivity, the two square contacts (4) and (5) are connected to the terminals of the current source (14), the first contact (6) of the first structure (2) is connected with the third contact (11) of the second (3), the second contact (8) of the first structure (2) is connected to the fourth contact (13) of the second (3), the third contact (10) of the first structure (2) is connected with the first contact (7) of the second (3), and the fourth contact (12) of the first structure (2) is connected to the second contact (9) of the second (3), the first (6) and the third contact (10) of the first structure (2) are the differential output (16) for one orthogonal plane component of the magnetic field (15), and the second (9) and the fourth contact (13) of the second structure (3) are the differential output (17) for the other orthogonal plane component of the magnetic field (15).