BG113806A - The hall plane-sensitive microsensor - Google Patents

Abstract

The Hall plane-sensitive microsensor contains a current source (1) and a rectangular semiconductor substrate (2) with n-type impurity conductivit. Five rectangular ohmic contacts, first (3), second (4), third (5), fourth (6), and fifth (7), all parallel to their long sides, are formed in series on one side of it at distances apart. The first (3) and fifth (7), and the second (4) and fourth (6) contacts, respectively, are symmetrical with respect to the third (5), which is central. The second (4) and fourth (6) contacts are close to the central (5) contact. One p-type rectangular bounding zone (8) and (9) is formed on their other long sides and in their vicinity, penetrating the volume of the substrate (2). The first (3) and fifth (7) contacts are located next to the p-type zones (8) and (9). The opposite plane to that with the contacts (3), (4), (5), (6) and (7) contains a highly conductive layer (10). The first contact (3) and the fifth contact (7) are immediately electrically connected and via the current source (1) are connected to the central contact (5). The second (4) and fourth (6) contacts are the differential output (11) of the Hall effect microsensor with the measured magnetic field (12) parallel to both the plane of the substrate (2) and the long sides of the ohmic contacts (3), (4), (5), (6) and (7).

Description

PLANAR-SENSITIVE HALL MICROSENSOR

TECHNICAL FIELD

The invention relates to a planar-sensitive Hall microsensor applicable in the field of robotics; automotive industry, including hybrid vehicles and electric vehicles; artificial intelligence security systems; robotic and minimally invasive surgery; low-field and high-precision magnetometry; quantum communication and navigation; process automation, including contactless automation; in underwater, ground and air surveillance and prevention systems; counterterrorism, etc.

PRIOR ART

A planar-sensitive Hall microsensor is known, containing a rectangular semiconductor substrate with n-type impurity conductivity. On one side of it, at distances from each other, five rectangular ohmic contacts are formed sequentially - first, second, third, fourth and fifth, all parallel to their long sides. The first and fifth, and respectively the second and fourth contacts are symmetrical to the third, which is central. The second and fourth contacts are located in the middle zones between the central and end contacts. The first and fifth contacts are directly electrically connected and are connected to the third through a current source. The second and fourth contacts are the differential output of the Hall microsensor, and the measured magnetic field is parallel to both the plane of the substrate and the long sides of the ohmic contacts, [1-9].

A disadvantage of this planar-sensitive Hall microsensor is the low magnetic sensitivity (conversion efficiency) due to the generation of a significantly lower Hall voltage in the output contact areas due to a) the smaller supply current than that entering through the central contact in the substrate, since the output voltage is determined by oppositely directed current components, each of which is about two times smaller than the incoming current, b) the horizontal flow of part of the supply current through the output contact areas, planarly located simultaneously with the supply ones on the same surface of the substrate.

Another disadvantage is the reduced metrological accuracy as a result of the low sensitivity, leading to a noticeable presence in the output voltage of parasitic signals from typical sensor flaws such as temperature drift, hysteresis, internal 1//(flicker) noise, offset, etc.

TECHNICAL ESSENCE

The task of the invention is to create a planar-sensitive Hall microsensor with high magnetic sensitivity and increased measurement accuracy.

This task is solved with a planar-sensitive Hall microsensor, containing a current source and a rectangular semiconductor substrate with n-type impurity conductivity. On one side of it, at distances from each other, five rectangular ohmic contacts are formed sequentially - first, second, third, fourth and fifth, all parallel to their long sides. The first and fifth, and respectively the second and fourth contacts are symmetrical to the third, which is central. The second and fourth contacts are near the central one. On their other long sides and near them, a /?-type rectangular limiting zone is formed, penetrating into the volume of the substrate. The first and fifth contacts are located next to the p-type zones. The plane opposite the one with the contacts contains a highly conductive layer. The first and fifth contacts are directly electrically connected and are connected to the central one through the current source. The second and fourth contacts are the differential output of the Hall microsensor as the measured magnetic field is parallel to both the plane of the substrate and the long sides of the ohmic contacts.

An advantage of the invention is the high magnetic sensitivity resulting from four factors. The first is the two restrictive /?-type zones near the output contacts, contributing to a significantly deeper penetration into the volume of the entire supply current from the central contact before its division into two opposite components, which significantly increases the lateral Lorentz deviation of the entire current in a magnetic field; The second is the greatly reduced horizontal components of the supply current in the near-surface region of the substrate by the formed deep p-type zones on the long sides of the second and fourth contacts; The third is the accumulating role of the restrictive p-type zones near the output contacts of negative and positive charges on them in a magnetic field, from the incoming current through the central contact, which increases the Hall voltage; and The fourth is the highly conductive layer on the opposite side of the substrate, also contributing to a deeper penetration of the current from the third contact into the substrate. This is why the significantly higher supply current in the Hall mechanism generates a significantly higher output voltage value, i.e. magnetosensitivity.

Another advantage is the increased metrological resolution when detecting the minimum magnetic induction 5 _m i _n due to the increased signal-to-noise ratio through the high sensitivity and the greatly reduced noise fluctuations with the help of the deep /?-type zones surrounding the second and fourth contacts.

Another advantage is the increased measurement accuracy due to high sensitivity and reduced noise fluctuations.

DESCRIPTION OF THE APPENDIX FIGURES

The invention is explained in more detail by an exemplary embodiment thereof, schematically shown in the attached Figure 1, representing the cross-section of the Hall microsensor.

EXAMPLES OF IMPLEMENTATION

The planar Hall-sensitive microsensor contains a current source 1 and a rectangular semiconductor substrate 2 with i-type impurity conductivity. On one side of it, at distances from each other, five rectangular ohmic contacts are formed sequentially - the first 3, the second 4, the third 5, the fourth 6 and the fifth 7, all parallel to their long sides. The first 3 and the fifth 7, and the second 4 and the fourth 6, respectively, are symmetrical to the third 5, which is central. The second 4 and the fourth 6 contacts are near the central 5. On their other long sides and near them, a p-type rectangular limiting zone 8 and 9 is formed, penetrating into the volume of the substrate 2. The first 3 and the fifth 7 contacts are located next to the p-type zones 8 and 9. The plane opposite the one with the contacts 3, 4, 5, 6 and 7 contains a highly conductive layer 10. The first 3 and the fifth 7 contacts are directly electrically connected and are connected to the central 5 through the current source 1. The second 4 and the fourth 6 contacts are the differential output 11 of the Hall microsensor, as the measured magnetic field 12 is parallel to both the plane of the substrate 2 and the long sides of the ohmic contacts 3, 4, 5, 6 and 7.

The operation of the planar-sensitive Hall microsensor, also known as vertical, according to the invention is as follows. When the current source 1 is connected to the contacts 5 and 3-7, the supply current / ₅ flows through the central electrode 5 in the volume of the substrate 1. As a result of the original technical solution - the low-alloy p-type zones (rings) 8 and 9 formed near the contacts 4 and 6, the entire current / ₅ penetrates into the depth of the substrate 2 without lateral scattering. These zones 8 and 9 do not allow the separation of the current / 5 close to the surface into two components / 53 and -/ _5>7 directed oppositely to the end contacts 3 and 7; (/5/2) = /5,3 = ΙΑ?!· The equality of these currents is a consequence of the symmetry of the structure 2 with respect to the central terminal 5. After a certain degree of penetration, depending on the dimensions of the electrodes 3, 5 and 7, the current strength / ₅ , the depth of the p-type zones 8 and 9, and the effective resistance R* of the substrate 2, i.e. the concentration of the doping impurity, for example phosphorus P, the supply current / ₅ is divided into two equal components / _5;3 and -/ _5>7 , directed to electrodes 3 and 7. The trajectories of the electrons in the substrate 2 are curvilinear, [5,6,8,9]. A prerequisite for the vertical penetration w of the current / ₅ is also the equipotentiality of the central ohmic contact 5 in the absence of a magnetic field B 12. In general, this depth w at a fixed concentration of the donor impurity N _D in the n-type substrate 2 depends on the ratio M between the width / 1 of the supply contact 5, or 3 and 7, and the distances I2 between them, M = /]// ₂ , [8]. The calculated depth w at the most commonly used in microelectronics concentration of doping donor impurities N _D ~ 10 ¹⁵ cm' ³ in Si and, for example, a distance / 2 ~ 30 pm constitutes about w ~ 30 - 40 pm. At the same time, a vertical directing effect on the current /5 is performed by the two /?-type zones 8 and 9 adjacent to the central contact 5. The proximity of the low-doped p-type rings 8 and 9 to the p ⁺ contacts is determined by the technological processes used to realize the sensor IC. The kinetics of the electrons is also enhanced to a large extent by the highly conductive layer 10 with a floating potential on the opposite side, Figure 1. At the same time, the p-type limiting rings 8 and 9 prevent the flow of the supply current /5 along the surface of the substrate 2. As a result, metrological errors and fluctuations of the output 11 are greatly minimized, and the accuracy is increased.

In the presence of an external magnetic field B 12, the currents / ₅ , / 53 and -/ 5 7 are subjected to the deflecting lateral action of the Lorentz forces = i?V _dr x B, where q is the elementary charge of the electron, and Usht is the vector of the average drift velocity of the current carriers. That is why the current lines are deformed. The central current / ₅ , responsible in our case for the magnetic susceptibility, is deflected to the left or right, Figure 1. The generated current carriers accumulate/accumulate in the areas of the output contacts 4 and 6. The rings 8 and 9 near contacts 4 and 6 do not allow the additional non-equilibrium electrons generated by the Lorentz forces to leak out. Their concentration, for example, positive charges on contact 4 and negative on terminal 6, significantly increases the output voltage of the Hall Vn4,b(^) I. At the same time, through the Lorentz forces, currents / _{5 3} and -/5,7 "contract" towards the upper side of the structure 2, or "unfold" in its volume. This behavior is determined by the directions of the field B 12 and the individual components / ₅₃ and -/5 7.

The unexpected positive effect of the new technical solution lies in the specific design. With the help of the two /?-type zones 8 and 9, the entire current / ₅ entering the microsensor penetrates deep into the volume of the substrate 2. For the first time in this class of Hall elements, an approach is used that increases the magnetic sensitivity by Lorentzian deviation of practically the entire supply current / 5. In the new configuration, the output terminals 4 and 6 are located significantly closer to the central supply contact 5 as opposed to the previously common location where they are either next to the end contacts 3 and 7, or in the middle parts between the central 5 and electrodes 3 and 7. The proposed solution contains several advantages: a) the magnetic sensitivity increases by about two times; b) the signal-to-noise ratio increases, simultaneously with the resolution when detecting the minimum magnetic induction B _min 12, including the measurement accuracy increases.

The planar Hall-sensitive microsensor can be implemented with CMOS, BiCMOS or micromachining microelectronic technologies. The ohmic contacts 3, 4, 5, 6 and 7 are highly doped n ⁺ regions formed by epitaxy and with a depth of about 1 pm. The low-doped /?-type regions 8 and 9 can be replaced by “trench” or “trench” of appropriate depth (trench etch depth) by the etching procedure. The highly conductive layer 10 is implemented both with metallization and with a highly conductive “buried” (buried) n ⁺ -layer. The object of optimization can be the widths of the central contact 5 and the output terminals 4 and 6. Thus, it is possible to achieve simultaneously the most significant depth of vertical penetration of the current / ₅ into the volume as well as the maximum value of the output voltage 11. The Hall microsensor can operate in a wide temperature range, including in a cryogenic environment, which improves its main characteristics. For even higher conversion efficiency for the purposes of weak-field and high-precision magnetometry, seismology, counterterrorism, navigation, etc., the silicon chip with the microsensor can be placed between two identical field concentrators B 12 made of ferrite or μ-metal. For even higher magnetoelectric conversion, the n-GaAs semiconductor from the AB group should be used, whose electron mobility μ _η at room temperature T = 300 K is more than 8 times higher than that of n-Si. The new sensor solution is suitable for 2D and 3D vector magnetometers.

APPENDIX: one figure

LITERATURE

[1] S. Schott, Vertical hall sensor, US Patent No. US20100133632A1/03.06.2010.

[2] A.M.J. Huiser, H.P. Baltes, Numerical modeling of vertical Hall-effect devices, IEEE Electron Device Letters, EDL-5(11) (1984) pp. 468-470.

[3] R.S. Popovic, The vertical Hall-effect device, IEEE Electron Device Letters, EDL-5(9) (1984), pp. 357-358.

[4] R. Popovic, Integrated Hall element, US Patent 4,782,375 Al/01.11.1988.

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

[6] C. Sander, M.-C. Vecchi, M. Cornils, O. Paul, From three-contact vertical Hall elements to symmetrized vertical Hall sensors with low offset, Sensors and Actuators, A 240 (2016) pp. 92-102.

[7] T. Kaufmann, On the offset and sensitivity of CMOS-based five-contact vertical Hall devices, in "MEMS Technology and Engineering", v. 21, Der Andere Verlag, 2013, p. 147; ISBN: 978-3-86247-374-8.

[8] C. Roumenin, Microsensors for magnetic field, Ch. 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.

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

Claims (1)

PATENT CLAIMS A planar Hall-type microsensor comprising a current source and a rectangular semiconductor substrate with n-type impurity conductivity, on one side of which five rectangular ohmic contacts are formed sequentially at distances from each other - first, second, third, fourth and fifth, all parallel to their long sides, the first and fifth, and respectively the second and fourth contacts are symmetrical to the third, which is central, the first and fifth contacts are directly electrically connected and are connected to the central one through the current source, the second and fourth contacts are the differential output of the microsensor, the measured magnetic field being parallel to both the plane of the substrate and the long sides of the contacts, CHARACTERIZED in that the second (4) and fourth (6) contacts are in the vicinity of the central one (5), on their other long sides and in the vicinity of them a p-type rectangular limiting zone (8) is formed and (9), penetrating into the volume of the substrate (2), the first (3) and the fifth (7) contacts are located next to the p-type zones (8) and (9) as the plane opposite to that with the contacts (3), (4), (5), (6) and (7) contains a highly conductive layer (10).