BG112808A - Hall effect microsensor with an in-plane sensitivity - Google Patents

Abstract

The Hall microsensor with an in-plane sensitivity contains a rectangular semiconductor wafer (1) with n-type hopping conduction, as on one of its sides are formed three rectangular ohmic contacts in series and at equal distances - first (4), second (5) and third (6), as the first (4) and the third (6) are terminal and the second (5) is central, all of them are parallel to their long sides. The magnetic field (13) which is measured is parallel to both the plain of the wafer (1) and the long sides of the ohmic contacts (4, 5 and 6). One of the exits of a current source (11) is connected to the central contact (5) and the wafer (1). There are two other identical semiconductor wafers (1 and 3), on one of the sides of which there are two ohmic contacts at the same distance - sequentially from left to right first (7 and 9), and second respectively (8 and 10). ). The contacts (4, 5, 6, 7, 8, 9 and 10) of the wafers (1, 2 and 3) are parallel to their long sides. Contact (7) of the wafer (1) and contact (9) of the wafer (3) are connected to the other terminal of the current source (11). Contact (8) of the wafer (1) and contact (4) of the wafer (2), as well as contact (6) of the wafer (2) and contact (9) of the wafer (3) are respectively connected to each other, as the connections between the contacts (8 and 4), and (6 and 9) respectively, form the differential output (12) of the Hall microsensor.

Description

HALL MICROSENSOR WITH PLANE SENSITIVITY

TECHNICAL FIELD

The invention relates to a Hall microsensor with planar sensitivity, applicable in the field of robotics and mechatronics; contactless automation; measurement of angular and linear displacements; weak-field magnetometry; multi-rotor unmanned aerial vehicles; navigation; 3D robotic and minimally invasive surgery, including telemedicine; electric vehicle construction; energy; positioning of objects in the plane and space; intelligent quantum communication systems; military affairs; counterterrorism and security, etc.

PRIOR ART

A Hall microsensor with planar sensitivity is known, containing a semiconductor substrate with i-type impurity conductivity, on one side of which three rectangular ohmic contacts are formed at equal distances from each other - one central and two end contacts. The end contacts are symmetrical with respect to the long sides of the central one. With one load resistor each, the end contacts are connected to one terminal of a current source, the other terminal of which is connected to the central contact. The differential output of the Hall microsensor is the end contacts, as the measured magnetic field is parallel to the plane of the substrate and to the long sides of the contacts, [1-8].

A disadvantage of this Hall microsensor with planar sensitivity is its complicated implementation through the integrated silicon technologies used in microelectronics, requiring inherently different physicochemical processes for the formation of the contacts on the substrate on the one hand, and for the implementation of the two load resistors on the other.

A disadvantage of the microsensor is also the reduced metrological accuracy as a result of significant temperature drift of the output voltage due to the different temperature coefficients of the substrate and load resistors.

TECHNICAL ESSENCE

The task of the invention is to create a Hall microsensor with planar sensitivity, which has a simplified technological implementation and high metrological accuracy.

This task is solved with a Hall microsensor with planar sensitivity, containing three semiconductor substrates with i-type impurity conductivity and a rectangular shape - sequentially first, second and third, arranged parallel to each other. On one side of the second substrate, three rectangular ohmic contacts are formed at equal distances - first, second and third, with the first and third being extreme, and the second being central. Also, on one side of the first and third substrates, which are the same, there are two ohmic contacts at the same distance - sequentially from left to right, first and second. The contacts of all substrates are parallel to their long sides. The first contact of the first substrate and the second contact of the third are connected to one terminal of a current source, the other terminal of which is connected to the central contact of the second substrate. The second contact of the first substrate and the first contact of the second, as well as the third contact of the second substrate and the first contact of the third are respectively connected to each other. The connections between these contacts form the differential output of the Hall microsensor, with the measured magnetic field parallel to the planes of the pads and the long sides of the contacts.

An advantage of the invention is the full technological compatibility through uniform physicochemical processes of silicon technologies used in microelectronics for the complete realization of the contacts on the pads and resistors of the Hall microsensor.

Another advantage is the increased measurement accuracy resulting from the minimal temperature drift of the output due to the identical temperature coefficients of all i-type semiconductor substrates.

Another advantage is the reduced or compensated (zeroed) parasitic output voltage (offset) of the microsensor in the absence of a magnetic field due to the original connection of the end contacts of the three pads, with this specific shunting, compensating currents flow between the three structures, equalizing the electrical potentials in them in the absence of a magnetic field, including in the areas of the two output contacts.

Another advantage is the unchanged conversion efficiency (sensitivity) of the new solution and the microsensor's two load resistors as a result of generating additional Hall potentials with the same sign in a magnetic field on the corresponding contacts of the first and third pads, connected to the end contacts of the second pad, forming the output.

DESCRIPTION OF THE APPENDIX FIGURES

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

EXAMPLES OF IMPLEMENTATION

The Hall microsensor with planar sensitivity contains three semiconductor substrates with n-type impurity conductivity and a rectangular shape - first 1, second 2 and third 3, arranged in parallel to each other. On one side of the second substrate 2, three rectangular ohmic contacts are formed at equal distances - first 4, second 5 and third 6, with the first 4 and third 6 being the ends, and the second 5 being the center. Also, on one side of the first 1 and the third 3 substrates, which are identical, there are two ohmic contacts at the same distance - first 7 and 9, respectively, from left to right, and second 8 and 10, respectively. Contacts 4, 5, 6, 7, 8, 9 and 10 on substrates 1, 2 and 3 are parallel to their long sides. The first contact 7 of the first pad 1 and the second contact 9 of the third 3 are connected to one terminal of a current source 11, the other terminal of which is connected to the central contact 5 of the second pad 2. The second contact 8 of the first pad 1 and the first contact 4 of the second 2, as well as the third contact 6 of the second pad 2 and the first contact 9 of the third 3 are respectively connected to each other. The connections between these contacts 8 and 4, respectively 6 and 9 form the differential output 12 of the Hall microsensor, as the measured magnetic field 13 is parallel to the planes of the pads and to the long sides of the contacts 4, 5, 6, 7, 8, 9 and 10.

The operation of the Hall microsensor with planar sensitivity, according to the invention, is based on the generation of the Hall effect by a magnetic field parallel to the semiconductor planes (contrary to the generally accepted vertical activation of the Hall phenomenon) — a regularity discovered and used for the first time by Ch. Rumenin and P. Kostov [1,2,4-6], and further developed by S. Lozanova [8], is as follows. Given the planarity of the ohmic contacts 4, 5, 6, 7, 8, 9 and 10, Figure 1, when the current source Es 11 is turned on and the magnetic field B = 0 is absent, they represent equipotential planes. The current paths through these contact surfaces are initially directed vertically downwards into the volume of the pads 1, 2 and 3, then become parallel to their upper sides, and finally are again perpendicular to the sides of the pads 1, 2 and 3. Therefore, the current lines are curvilinear. According to the innovative connection of the pairs of contacts 4 — 8,6 — 9 and 7 - 10, the directions of the equal in value supply currents through them are oppositely directed. As a result of possible geometric asymmetry, technological imperfections, internal mechanical stresses, temperature fluctuations, etc., an offset E _n (B = 0) # 0 may occur at the output Ει ₂ ^Ξ Ε _8; 9 12 of the configuration in Figure 1. In fact, the existence of such a parasitic output voltage means that an electrical asymmetry has occurred in the identical structures 1, 2 and 3. In the proposed solution, Figure 1, overcoming this serious sensor defect is achieved by directly connecting contacts 4 — 8, 6 - 9 and 7 — 10 to pads 1, 2 3. With such a non-standard shorting, compensating (equalizing) currents flow between the pads 1, 2 and 3 themselves, equalizing the electrical conditions (potentials) in them. Therefore, in the areas of the two output contacts 8-4 and 9-6 in the absence of a magnetic field B 13, B = 0, the offset is drastically reduced or compensated (zeroed), Ei ₂ (B = 0) = E ₈₉ (B = 0) ~ 0. This approach, compared to the complex dynamic offset compensation or so-called current spinning [7], is significantly simplified and is immanent in the technical solution itself, as the final results in both cases are very close.

Applying the measured magnetic field B 13 parallel to the pads 1, 2 and 3 and to the long sides of contacts 4, 5, 6, 7, 8, 9 and 10 hlu mil leads to a lateral deflection of the nonlinear current lines along their entire length. This is a result of the action of the Lorentz forces F _L(i , F _Li = 7 Kir x B, where q is the elementary charge of the electron, and Vdr is the vector of the average drift velocity of the electrons in the volumes of substrates 1, 2 and 3. (In Figure 1, the magnetic vector B 13 is perpendicular to the cross sections of structures 1, 2 and 3). As a result of the Lorentz deviation from the forces Fy, depending on the directions of the supply currents in substrates 1, 2 and 3, and the magnetic field B 13, the nonlinear trajectories “contract” and/or “expand”, respectively. For this reason, Hall potentials are simultaneously generated on the planar contacts 4-8, 6-9, equal in value and with opposite sign: and - Unb(^)> and UnvF) and - Udof) In fact, the measured magnetic field B 13 violates the overall electrical symmetry of the currents trajectories relative to the central contact 5 in pad 2. At the same time, a Hall voltage, Vi2(F), appears on the differential output 12 of the microsensor. It is generated by the oppositely flowing supply currents Λ.4 and - /5.6 in the second 2 pad, leading to an increase and, respectively, a decrease in the potentials of contacts 4 and 6 from the Lorentz forces acting in opposite directions. The conversion efficiency (sensitivity) of the new solution also remains unchanged compared to the microsensor with the two load resistors. The reason is that in a magnetic field B 13 additional Hall potentials U _H 8 and - V _H 9 with the same sign as those on contacts 4 and 6 are generated, which stabilizes the value of the output signal Vn^)· The voltage ΡηζΒ) is a linear and odd function of the strength and direction of the total supply current / ₅ and the polarity of the magnetic field B 13. It should also be noted the role of the surface magnetically controlled current in the three structures 1, 2 and 3, further increasing the output voltage W), [9].

In the new solution, magnetoresistive structures are used for the first time - pads 1 and 2 with pairs of contacts 7-8 and 9-10, Figure 1. They replace the load resistors from the known solution. That is why both the basic magnetosensitive element - pad 2 with contacts 4-5-6, and structures 1 and 3 with contacts 7, 8, 9 and 10 are implemented in a single technological cycle and with the same physicochemical processes, which significantly simplifies the implementation of the Hall microsensor. In addition, in the field B 13 the resistances of the two resistors Ri and R ₃ , formed with pads 1 and 3 only increase by the same value, MR ~ B ² . As a result, this change, which at low values of the induction B 13 in silicon is about 1 - 2 %, does not affect the output voltage Vi2(F), since the output 12 is differential. The simultaneous additional increase in the magnetoresistances AR _{7 S} (B) and DV ₉ ю(B) by the same value is the in-phase component in the output 12.

I'll do it.

The unexpected positive effect of the new technical solution is that through the original design, containing magnetoresistors instead of load resistors and the innovative connection of pads 1, 2 and 3, full technological compatibility, increased measurement accuracy as a result of minimal temperature drift, reduced or compensated parasitic offset and unchanged sensitivity are achieved.

The technological implementation of the Hall microsensor with planar sensitivity is carried out on the basis of silicon CMOS or BiCMOS integral processes. In this case, p-type “pockets” are formed in p-Si wafers. The planar ohmic contacts 4, 5, 6, 7, 8, 9 and 10 are formed by ion implantation and are heavily doped p ⁺ - regions in n-Si “pockets”. By changing the distance between the pairs of contacts 7-8 and 9-10 on pads 1 and 3, the required value of the “load” resistors in the new solution is achieved. Silicon planar technologies allow the simultaneous formation of a common chip and the processing electronic circuitry of the output voltage depending on the specific application. The configuration is also operable in the cryogenic temperature range, for example, the boiling point of liquid nitrogen T = 77 K, which expands the scope of application, especially in weak-field magnetometry and counterterrorism.

APPENDIX: one figure

LITERATURE

[1] Ch.S. Rumenin, P.T. Kostov, Planar Hall sensor, Author's certificate BG№ 37208/26.12.1983.

[2] S. Roumenin, Bipolar magnetotransistor sensors - An invited review, Sensors and Actuators, A 24 (1990) 83-105.

[3] A.M.J. Huiser, H.P. Baltes, Numerical modeling of vertical Hall-effect devices, IEEE Electron Device Letters, 5(9) (1984) pp. 482-484.

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[4] C. Roumenin, Parallel-field Hall microsensors - An overview, Sensors and Actuators, A 30 (1992) 77-87.

[5] Ch. Roumenin, Solid State Magnetic Sensors, Elsevier, Amsterdam, 1994, p. 450; ISBN: 0 444 89401.

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

[7] Sander, Ch., Vecchi, M., Cornils, M„ Paul, O. From Three-contact vertical Hall elements to symmetrized vertical Hall sensors with low offset, Sens. Actuators, A 240 (2016), 92-102.

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

[9] C. Roumenin, S. Lozanova, S. Noykov, Experimental evidence of magnetically controlled surface current in Hall devices, Sens. Actuators, A 175 (2012) 47-52.

Claims (1)

PATENT CLAIMS Hall microsensor with plane sensitivity, containing a rectangular semiconductor substrate with i-type impurity conductivity, on one side are formed sequentially and at equal distances three rectangular ohmic contacts - first, second and third as the first and third are terminal and the second - central , all parallel to its long sides, the measured magnetic field is parallel to the plane of the substrate and the long sides of the contacts, there is another current source, one terminal of which is connected to the central contact of the substrate, CHARACTERIZED by the fact that there are two more identical semiconductor pads (1) and (3), on one of the sides of which there are two ohmic contacts at the same distance - successively from left to right first (7) and (9), and respectively second (8). ) and (10), contacts (4), (5), (6), (7), (8), (9) and (10) of pads (1), (2) and (3) are parallel to long sides, the first contact (7) of the pad (1) and the second contact (9) of the pad (3) are connected connected to the other terminal of the current source (11), the second contact (8) of the substrate (1) and the first contact (4) of the substrate (2), as well as the third contact (6) of the substrate (2) and the first contact (9) of pad (3) are respectively interconnected, the connections between contacts (8) and (4), and respectively (6) and (9) form the differential output (12) of the Hall microsensor.