BG113292A - BIAXIAL MAGNETO SENSITIVE SENSOR CONTAINING HALL ELEMENTS - Google Patents

Abstract

The biaxial magnetosensitive sensor containing Hall elements covers a semiconductor substrate (1) with p-type conductivity. On one of its sides, four identical rectangular structures of the same semiconductor with n-type conductivity are formed, arranged in the form of an equilateral cross - clockwise first (2), second (3), third (4) and fourth (5), forming Hall elements. Each of these elements contains three ohmic contacts - from the outside to the inside of the n-structures (2, 3, 4 and 5) sequentially first (6, 7, 8 and 9), second (10, 11, 12 and 13), and third (14, 15, 16 and 17). Contacts (10 and 13) are connected to a current source (18). Pins (16 and 17) are connected, pins (11 and 12) are connected, and pins (14 and 15) are also connected. Contacts (7 and 9) and respectively (6 and 8) are differential outputs (19 and 20) for the two orthogonal planar components of the measured magnetic field (21), which is in the plane of the substrate (1) and has an arbitrary orientation.

Description

BIAXIAL MAGNETO SENSITIVE SENSOR CONTAINING HALL ELEMENTS

FIELD OF ENGINEERING

The invention relates to a biaxial magnetosensitive sensor containing Hall elements, applicable in the field of robotics and mechatronic systems with artificial intelligence; quantum communication; 3D robotic medicine and minimally invasive surgery, including laparoscopy; the determination of uniaxial pressure by means of a magnetic modulator displacement system; contactless automation; control and measurement technology and weak-field magnetometry; the automotive industry, including hybrid vehicles and electric vehicles; energy; the remote measurement of angular and linear displacements and the positioning of objects in the plane; navigation; biomedical research; military and security, including underwater, land and air surveillance and prevention systems; counterterrorism, etc.

PRIOR ART

A biaxial magnetosensitive sensor containing Hall elements is known, comprising an n-type semiconductor substrate, on one side of which identical Hall elements are formed, formed by a common central ohmic contact with a square shape as at distances and symmetrical to its four sides, there are successively one rectangular internal ohmic contact and one rectangular external ohmic contact each. In the vicinity of the equilateral cross-shaped configuration so identified on the surface of the p-substrate, a deep p ⁺ -type ring, also in the form of an equilateral cross, is formed surrounding it. The four external contacts are connected and through a current source are connected to the central contact. The measured magnetic field is in the plane of the substrate and has an arbitrary orientation, as each pair of opposite to the central internal contacts are the differential outputs for the two orthogonal planar components of the magnetic field, [1-10].

A disadvantage of this biaxial magnetosensitive sensor containing Hall elements is the reduced sensitivity of the outputs due to the occurrence of surface conductive channels between the corresponding power contacts - the central and external ones due to the presence on the surface of positively charged electronic states, impurity atoms, clusters, adsorbed nanoparticles, etc. which channels shunt Hall potentials and voltages onto the output internal contacts.

A disadvantage is also the reduced measurement accuracy of the two outputs due to the presence between them of a parasitic inter-channel influence through the volume of their common i-substrate.

TECHNICAL ESSENCE

The task of the invention is to create a biaxial magnetosensitive sensor containing Hall elements with high sensitivity at both outputs and increased measurement accuracy of the output channels, minimizing the parasitic influence between them.

This task is solved with a biaxial magnetosensitive sensor containing Hall elements covering a semiconductor substrate with rtype impurity conductivity. Four identical rectangular structures of the same semiconductor with l-type impurity conductivity are formed on one side, arranged in the shape of an equilateral cross clockwise first, second, third and fourth, forming Hall elements. Each of these elements contains three ohmic contacts - from the outside to the inside of the «-structures successively first, second and third. The second contacts of the first and fourth structures are connected to a current source. The third contacts of the third and fourth structures are connected, the second contacts of the second and third structures are connected, and the third contacts of the first and second structures are also connected. The first contacts of the second and fourth structures, and respectively the first contacts of the first and third structures, are the differential outputs for the two orthogonal planar components of the measured magnetic field, which is in the plane of the substrate and has an arbitrary orientation.

An advantage of the invention is the high magnetic sensitivity of the two outputs, since the first (output) contacts of the four structures are outside the areas through which the supply currents flow and their shunting negative influence on the two outputs is removed.

An advantage is also the significantly reduced parasitic voltage of the two outputs in the absence of a magnetic field (offsets) as a result of the original series connection of the third contacts of the Hall elements, which leads to averaging and compensation of possible negative signals associated with geometric and technological imperfections, breaking the symmetry of individual structures.

Another advantage is the high measurement accuracy of the two sensor channels, since there is no mutual parasitic influence between the outputs as a result of the separately formed Hall elements, generating the information voltages only for the orthogonal components of the magnetic field as well as the reduced offset.

An advantage is also the increased resolution when measuring the minimum magnetic induction, due to the high sensitivity, the reduced offset and the reduced internal 1// (flicker) noise due to the fact that the supply currents do not flow through the areas with the first (output) contacts.

DESCRIPTION OF THE ATTACHED FIGURES

The invention is explained in more detail with an exemplary embodiment given in the attached Figure 1.

IMPLEMENTATION EXAMPLES

The biaxial magnetosensitive sensor containing Hall elements covers a semiconductor substrate 1 with p-type impurity conductivity. On one side of it, four identical rectangular structures of the same semiconductor with n-type impurity conductivity are formed, arranged in the form of an equilateral cross - clockwise first 2, second 3, third 4 and fourth 5, forming Hall elements. Each of these elements contains three ohmic contacts - from the outside to the inside of pstructures (2), (3), (4) and (5) sequentially first 6, 7, 8 and 9, second 10,11, 12 and 13, and third 14, 15, 16 and 17. The second contacts 10 and 13 of the first 2 and the fourth 5 structure are connected to a current source 18. The third contacts 16 and 17 of the third 4 and the fourth 5 structure are connected, the second contacts 11 and 12 of the second 3 and the third 4 structure is connected and the third contacts 14 and 15 of the first 2 and the second 3 structure are connected. The first contacts 7 and 9 of the second 3 and the fourth 5 structure, and respectively the first contacts 6 and 8 of the first 2 and the third 4 are the differential outputs 19 and 20 for the two orthogonal planar components of the measured magnetic field 21, which is in the plane of the substrate 1 and is of arbitrary orientation.

The action of the biaxial magnetosensitive sensor containing Hall elements, according to the invention, is as follows. When connecting the contacts 16 - 17, 11 - 12 and 14 - 15 of the four n-type rectangular structures 2, 3, 4 and 5, a series connection of these identical Hall elements with planar sensitivity takes place. Therefore, after the connection of contacts 10 and 13 with the terminals of the current source 18, and the structural symmetry of the thus formed identical microsensors, four identical components /shdd = /15,11 = /12,16 = /13,17 = /18· Characteristic feature of the current trajectories is that they are initially perpendicular to the upper surface of the pad 1, because the power contacts 10, 14, 11, 15, 12, 16, 13 and 17 in the absence of a magnetic field, B = 0, 21 represent equipotential planes. The current lines penetrate the volume of the structures 2, 3, 4 and 5, after which their effective trajectories are parallel to the upper surface of the substrate 1. Furthermore, through the connection thus made, the currents in the Hall elements 2 and 4, and 3 and 5, respectively are in opposite directions: /u,14 = |- /12,10! and / _15> c = |- /13,17). In the absence of a magnetic field, 1? = 0, 21 at outputs 19 and 20 parasitic output voltages arise - offsets unrelated to the metrological purpose of the sensor. As a result, the measurement accuracy is significantly reduced. This disadvantage, for example, for the output 19, is the result of the electrical asymmetry caused mainly by a geometric misalignment in the arrangement of the contacts 6, 10, 14 and 8, 12, 16 of the oppositely located Hall elements with respect to the center of the configuration 2, 3, 4 and 5. The root cause is technological - unavoidable imperfections in alloying, misalignment of masks during photolithography, mechanical stresses mostly from the metallization and casing of the chip, temperature gradients and fluctuations, aging, etc. The same analysis is valid for the other sensor channel - 20, formed by contacts 3, 11, 15 and respectively 9, 13, 17 of structures 3 and 5. In the configuration of Figure 1 in the absence of a magnetic field, B = 0.21 offsets are minimized thanks to the connections made between contacts 16 - 17, 11 - 12 and 14 - 15 of structures 2, 3, 4 and 5. As a result, the potential asymmetry in the areas with output contacts 6 and 8, and respectively 7 and 9 is practically compensated. In fact, possible parasitic signals resulting from geometric and technological imperfections, including temperature drift of the offsets, are averaged and minimized. The integral realization of the i-type structures 2, 3, 4 and 5 formed on the p-substrate 1 ensures the complete electrical isolation between them. For this reason, the parasitic inter-channel influence of the two outputs 19 and 20 is prevented as it is in the known solution, increasing the measurement accuracy.

The measured magnetic field B 21 , which is in the plane x-y of the substrate 1 through its two mutually perpendicular components B _x and B _y leads to the occurrence of corresponding deflecting moving carriers in the current components Lorentz forces, F _Lj = dUsh x B, where q is the elementary charge of the electron, and V _dr is the average drift velocity vector of the electrons. Since all the current components are confined in the equilateral cross-shaped structures 2, 3, 4 and 5, the action of the Lorentz forces F\ of the B _x and B _y fields is highly effective on all parts of the trajectories. As a result, the current lines of the oppositely directed components /ju,14 and - /12,16, and respectively Zi5,ii and - /13,17 are deformed - they "shrink" or "expand" as on the output terminals 7 and 9, 6 and 8, respectively, Hall potentials are generated. This sensory action is a manifestation of the plane magnetosensitive Hall effect, [1 - 10]. The potentials form at the differential outputs 19 and 20 Hall voltages V ₁₉ (J5) and Ugoff), which are the information indicators for the two orthogonal components B _x and B _y of the magnetic field vector B 21. The voltages V^//?) and V ₂ i(T?) are linear and odd functions of the magnetic fields B _x and B _y . As a result of the construction of the biaxial magnetometer of Figure 1, the sensitivity of the two output channels 19 and 20 is substantially increased. The reason is that contacts 7 and 9, as well as 6 and 8, are located outside the areas of current flow /yudd = |- /12,10! and /15,11 = |-/13,17(. In this case, the shunting action of the surface electronic states on the Hall potentials is minimized and the voltages Vi ₉ (B) 19 and В ₂ o(^) 20 increase. Moreover, the orthogonality of the corresponding current components relative to the two plane vectors B _x and B _y of the magnetic field B 21 is technologically improved. Thus, the forces F _L ,i act maximally effectively on the components, generating significant Hall potentials on the surface of structures 2, 3, 4 and 5. The absolute value of the vector of the magnetic field B 21 in the x-y plane and the angle Θ of the field B 21 relative to a fixed reference axis in the same plane are given by the expressions: |B| = (B _x ² + B, ² ) ¹ ' ² and Θ = ta«-'(V _y (B _y )/V _x (B _x )), [1 - 3].

The new solution, Figure 1, increases the resolution of the sensor when measuring the minimum magnetic induction B _min . This result is a consequence not only of the high sensitivity and the reduced offset, but also of the reduced internal 1// (flicker) noise of both channels 19 and 20. The reason is that the supply currents /shdd = |- /12,10! ^and As.n = I ^- /13.17! ^{do not} flow through the zones with the first (output) contacts 7-9 and 6-8, which significantly limits the fluctuation processes in the information signals V^B) 19 and В ₂₀ (В) 20, [11].

The unexpected positive effect of the new technical solution is a consequence of the original cross-shaped configuration of three-contact Hall elements 2, 3, 4 and 5 and the innovative connection of the power contacts 16-17, 11-12 and 14-15. A drastic limitation of the negative effects and signals in the individual output channels 19 and 20 has been achieved. The achieved results are high channel magnetic sensitivity, increased measurement accuracy, removed inter-channel influence and high resolution.

The new sensor has a wide range of applicability in combination with magnetic modulator systems containing two or more permanent magnets, including those oriented relative to each other with their poles of the same name, for example for measuring uniaxial pressure in presses, etc.

The biaxial magnetosensitive sensor containing Hall elements can be realized with various modifications of the integral silicon technology - CMOS, BiCMOS, SOS, and if necessary, micromachining silicon processes can be used. The new 2-D microsensor also operates in the cryogenic temperature range, which increases sensitivity and further minimizes 1// noise on both channels, especially for weak-field magnetometry, navigation and counterterrorism purposes.

APPENDIX: one figure

LITERATURE

[1] C.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", ^2nd ed., The Adam Hilger series on sensors, Bristol, IOP Publ. Ltd, 2004, p. 419; ISBN: 0-7503-0855-2.

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

[4] C. Sander, M. Comils, M.C. Vecchi, O. Paul, Sensitivitatsoptimitechnik Kongress, 3013, pp. 559-562.

[5] C. Sander, C. Leube, O. Paul, Novel compact two-dimensional CMOS vertical Hall sensor, Proc. 18 ^th Intern. Conf, on Solid-State Sensors, Actuators and Microsystems, Transducers, 2015, pp. 1164-1167.

[6] R.S. Popovic, P. Kejik, S. Reymond, E. Swiss et al., Multi-axis integrated Hall magnetic sensors, Nucl. Technol. Radiat. Prot., 39(88), (2007), pp. 20-80.

[7] S. Reymond, P. Kejik, R. Popovic, True 2D CMOS integrated Hall sensor, IEEE Sens. J., (2007), pp. 860-863.

[8] M. Paranjape, L. Landsberger, M. Kahrizi, A 2-D vertical Hall magnetic field sensor using active carrier confinement and micromachining techniques, Proc, of the 8 ^th Intern. Confer, on Solid-State Sensors and Actuators, and Eurosensors IX, Transducers '95, Stockholm, 1995, pp. 253-256.

[9] S.V. Lozanova, Ch.S. Roumenin, Parallel-field silicon Hall effect microsensors with minimal design complexity, IEEE Sensors Journal, 9(7) (2009), pp. 761-766

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

[11] M. Madec, J.-B. Schell, J.-B. Kammerer, C. Lallement, L. Hebrard, Compact modeling of vertical hall-effect devices: electrical behavior, Analog Integr. Circ. Sig. Process, 77 (2013) pp. 183-195.

Claims (1)

A biaxial magnetosensitive sensor containing Hall elements comprising a semiconductor substrate, ohmic contacts forming Hall elements and arranged in the form of an equilateral cross, a current source such that the measured external magnetic field is in the plane of the substrate and is of arbitrary orientation, CHARACTERIZED in that the semiconductor substrate (1) has p-type impurity conductivity, four identical rectangular structures of the same semiconductor with l-type impurity conductivity are formed on one side, located in the shape of the equilateral cross - clockwise first (2), second ( 3), third (4) and fourth (5), forming the Hall elements, each of which contains three ohmic contacts from the outside to the inside of the l-structures (2), (3), (4) and (5) sequentially first ( 6), (7), (8) and (9), second (10), (11), (12) and (13), and third (14), (15), (16) and (17), the second contacts (10) and (13) of the first (2) and fourth (5) structures are connected to the current source (18), the third contacts (16) and (17) of the third (4) and fourth (5) structures are connected, the second contacts (11) and (12) of the second (3) and third (4) structures are connected, and the third contacts (14) and (15) of the first (2) and second (3) structures are connected, the first contacts (7) and (9) of the second (3) and fourth (5) structures, and respectively the first contacts (6) and (8) of the first (2 ) and the third (4) are the differential outputs (19) and (20) for the two orthogonal plane components of the magnetic field (21).