BG113275A - Planar magnetically sensitive element - Google Patents

Abstract

The planar magnetosensitive element contains a current source (1) and two identical semiconductor rectangular pads with n-type impurity conductivity - first (2) and second (3), located parallel to each other. On one side of each of the pads (2) and (3) consecutively and at equal distances, three identical rectangular ohmic contacts are formed from left to right - first (4) and (5), second (6) and (7), and third (8) and (9) located parallel to their long sides, contacts (6) and (7) being central. The surfaces of the two pads (2) and (3) between the first (4) and (5) and the central (6) and (7) as well as between the central (6) and (7) and the third (8) and (9) contacts are covered with a thin dielectric layer (10) of constant thickness, on which metal gate electrodes are formed - from left to right: first (11) and second (12) for the pad (2), and third (13) and fourth (14) ) for the pad (3). The first (11) and the second (12) gate electrode are simultaneously connected to the contact (7) of the pad (3), and the third (13) and the fourth (14) gate electrode are simultaneously connected to the contact (6) of the pad (2) . The third contacts (8) and (9) are connected, and the first (4) and (5) contacts are connected to the terminals of the current source (1). The contacts (6) and (7) are the differential output (15) of the element, the measured magnetic field (16) being parallel to both the planes of the pads (2) and (3) and the long sides of the contacts (4) , (5), (6), (7), (8) and (9).

Description

PLANA-MAGNETO-SENSITIVE ELEMENT

FIELD OF ENGINEERING

The invention relates to a planar magnetosensitive element applicable in the field of sensors, medicine including robotic and minimally invasive surgery, 3D telemedicine and laparoscopy, quantum communication, security systems with artificial intelligence, robotics, mechatronics, navigation, micro- and nano - technologies, contactless automation including remote measurement of angular and linear displacements, space research, control and measurement technology and weak-field magnetometry, electric cars and hybrid vehicles, energy, counter-terrorism, military affairs, etc.

PRIOR ART

A planar magnetosensitive element is known, containing a current source and a semiconductor rectangular substrate with l-type impurity conductivity, on one side of which three rectangular ohmic contacts are formed at equal distances from each other in succession - first, second and third, located parallel to their long sides as the second one is central and the other two contacts are located symmetrically to it on its two long sides. The first and third contacts through the load resistors are connected to one terminal of the current source, the other terminal of which is connected to the central contact. The measured magnetic field is parallel to both the substrate plane and the long sides of the rectangular contacts, and the first and third contacts are the output of the element, [1-6].

A disadvantage of this planar magnetosensitive element is the reduced conversion efficiency (sensitivity) as a result of the low mobility of the current carriers in the silicon semiconductor used in its technological implementation.

A disadvantage is also the reduced metrological accuracy due to the low magnetic sensitivity, leading to a noticeable presence in the output voltage of parasitic signals from sensor defects such as temperature drift, offset, hysteresis, internal 1// (flicker) noise, non-linearity, etc.

TECHNICAL ESSENCE

The task of the invention is to create a planar magnetosensitive element with high sensitivity and high metrological accuracy.

This task is solved with a planar magnetosensitive element containing a current source and two identical semiconductor rectangular pads with l-type impurity conductivity - first and second, located parallel to each other. On one side of each of the pads successively and at equal distances are formed from left to right three identical rectangular ohmic contacts - first, second and third, located parallel to their long sides, with the second contacts being central. The surfaces of the two pads between the first and central as well as between the central and third contacts are covered with a thin dielectric layer of constant thickness on which metal gate electrodes are formed — from left to right first and second for the first pad, and third and fourth for the second. The first and second gate electrodes are simultaneously connected to the center contact of the second pad, and the third and fourth gate electrodes are simultaneously connected to the center contact of the first pad. The two third contacts are connected, and the two first contacts are connected to the terminals of the current source. The central contacts are the differential output of the element, as the measured magnetic field is parallel both to the planes of the pads and to the long sides of the contacts.

An advantage of the invention is the high sensitivity due to the generation of additional electrical charges of the appropriate polarity under the dielectric layer by the pairs of gate electrodes in the two pads, leading to an increased Hall-type output voltage.

The advantage is also the increased measurement accuracy as a result of the high sensitivity at an unchanged level of the sensor parasitic signals - temperature drift, hysteresis, offset, non-linearity, internal (flicker) noise, etc.

An advantage is also the increased resolution when measuring the minimum magnetic induction, due to the high sensitivity at the same time as the increased signal-to-noise ratio of the element, which provides more detailed mapping of the planar and spatial topology of the magnetic field.

Another advantage is the implementation of the magnetosensitive element in a single cycle, without the need for technological processes that are different in nature, complicating the implementation of the load resistors and the two structural configurations with the ohmic contacts on the silicon chip.

DESCRIPTION OF THE ATTACHED FIGURES

The invention is explained in more detail with an exemplary embodiment given in the attached Figure 1, representing its cross-section.

IMPLEMENTATION EXAMPLES

The planar magnetosensitive element contains a current source 1 and two identical semiconductor rectangular pads with /g-type impurity conductivity - the first 2 and the second 3, located parallel to each other. On one side of each of the pads 2 and 3, successively and at equal distances, three identical rectangular ohmic contacts are formed from left to right - first 4 and 5, second 6 and 7, and third 8 and 9, located parallel to their long sides as contacts 6 and 7 are central. The surfaces of the two pads 2 and 3 between the first 4 and 5 and the central 6 and 7 as well as between the central 6 and 7 and the third 8 and 9 contacts are covered with a thin dielectric layer 10 of constant thickness on which metal gate electrodes are formed - from the left on the right, first 11 and second 12 for the first pad 2, and third 13 and fourth 14 for the second 3. The first 11 and second 12 gate electrodes are simultaneously connected to contact 7 of the second pad 3, and the third 13 and fourth 14 gate electrodes are simultaneously connected to contact 6 of the first pad 2. The two third contacts 8 and 9 are connected, and the two first 4 and 5 are connected to the terminals of the current source 1. Contacts 6 and 7 are the differential output 15 of the element with the measured magnetic field 16 being parallel as on the planes of the pads 2 and 3, as well as on the long sides of the contacts 4, 5, 6, 7, 8 and 9.

The action of the planar magnetosensitive element, according to the invention, is as follows. After the immediate connection of the third contacts 8 and 9, and the inclusion of the two first contacts 4 and 5 to the current source 1, in the volume of the two pads 2 and 3 flow two oppositely directed and equal in value current components and - ^9.5, Л, 8 = | - ^9.51 · Power supply planar contacts 4 and 8, respectively 9 and 5 represent equipotential planes to which, in the absence of an external magnetic field B 16, B = 0, the currents through them are always perpendicularly directed to the upper sides of the pads 2 and 3, penetrating deep into their volumes. The depth of penetration into the silicon structures, as is our case, at a fixed concentration of doping donor impurities N _D = const in substrates 2 and 3 depends on the ratio between the width of contacts 4, 8, 9 and 5 and the distance between them Z ₄ . ₈ and Z ₉ . ₅ . The maximum value of the depth at N _d ~ 10 cm' with optimized geometric parameters is about 30 - 40 pm. Between contacts 4 and 8 and respectively 9 and 5, the current lines in a first approximation are parallel to the upper sides of the pads 2 and 3, passing under the central contacts 6 and 7, Figure 1. As a result, the trajectories of the current carriers are curvilinear, [1-6] .

The application of the measured magnetic field B 16 parallel to the pads 2 and 3, and to the long sides of contacts 4, 5, 6, 7, 8 and 9 leads to a lateral (lateral) deviation (deflection) of the current lines along the entire length of their non-linear trajectories. The reason for this is the action of the Lorentz forces F^, F _L = qV _dt x B, where q is the elementary charge of the electron, and V _dr is the vector of the average drift velocity of the electrons in pads 2 and 3, [2,7, 8]. This method of magnetic activation of the Hall elements gives them their name - planar magnetosensitive sensors, in Figure 1 the magnetic vector B 11 is perpendicular to the cross sections of pads 2 and 3. As a result of the Lorentzian deviation from the forces F^, depending on the directions of the currents / _4>8 and /95, and in the magnetic field B 16, the non-linear trajectories in the volumes of pads 2 and 3 "shrink" and "expand", respectively. For this reason, Hall potentials φβ(Β) and - φη(Β\ φ^Β) = |- ^7(^)|, equal in value but opposite in sign, are simultaneously generated on the upper surfaces of the two planar magnetosensitive structures 2 and 3, which are registered with contacts 6 and 7. The actually measured magnetic field B 16 breaks the electrical symmetry of the current trajectories. Therefore' as a result of the Lorentz deflection, a Hall voltage V ₁₅ (B) = Vh,6-7(^) arises on the differential output 15 of the element. This signal is a linear and odd function of the strength of the currents / _4>8 and - / ₉₍₅ , as well as the magnetic field B 16. Due to the low mobility of electrons μ _η in silicon - the main semiconductor in integrated microelectronic technologies, significant values of the sensitivity S at room temperature, μ _η (Τ = 300 K) ~ 1200 cm^^s ¹ , [2,3,5,8,9]. As is well known, the conversion efficiency or sensitivity S is directly proportional to the mobility μ _η of electrons, S ~ μ _η , [2,8 ].

In the new solution in Figure 1, an innovative way of increasing the sensitivity has been chosen. The surfaces of the two pads 2 and 3 located between the first 4 and 5 and the central 6 and 7, as well as between the central 6 and 7 and the third 8 and 9 contacts are covered with a thin dielectric layer 10 of constant thickness, on which the metal gates are formed electrodes 11 and 12, and 13 and 14, respectively. They are separated from the interfaces of the upper planes of substrates 2 and 3 by a thin dielectric layer 10, parts of which have a constant thickness d _m ~ const. Layer 10 is primarily silicon dioxide SiO ₂ as in MOS transistors. The original connection of gate electrodes 13 and 14 with output contact 6, and respectively gate electrodes 11 and 12 with contact 7 induces through the potentials -φ _Ί and +^ ₆ a field effect in the thus formed MOS structures 2 and 3, [9,10] . If in i-type substrate 1, as is our case, for example, the gate potential is positive + φ^, in the interface areas under electrodes 13 and 14, additional electrons are extracted from the volume of substrate 3 by the field effect, i.e. the negative component of the Hall-type field -E _n increases. At a negative gate voltage -φ _Ί in the near-surface areas under gates 11 and 12, a regime of electron depletion is realized, i.e. the positive field component increases. The polarities of the gate potentials ±Vg are aligned with the action of the Lorentz force ±F^ and in practice the field effect amplifies the action of the Lorentz force. Therefore, the described process increases the output voltage of the microsensor KutisC^) 15. As a result of the technical solution of Figure 1, the magnetic sensitivity S and the measuring accuracy of the field B 15 increase. At the same time, the high signal Voutis^) 15 also leads to an increase in the signal-to-noise ratio (S/N) with the negative factors such as parasitic offset, nonlinearity, temperature drift, intrinsic (flicker) noise and hysteresis unchanged. Therefore, the resolution when measuring the minimum magnetic induction B _m j _n increases, which

Claims (1)

PATENT CLAIMS A planar magnetosensitive element containing a current source and a semiconductor rectangular substrate with i-type impurity conductivity, on one side of which three identical rectangular ohmic contacts first, second and third are formed sequentially and at equal distances from left to right, located parallel to their long sides such that the second contact 7 is central and the measured magnetic field is parallel to the plane of the pad and to the long sides of the contacts, CHARACTERIZED in that there is another second semiconductor pad (2) parallel to the first (2) and identical with it, on one side of which are also formed at equal distances from left to right three identical rectangular ohmic contacts - first (5), second (7) and third (9), located parallel to their long sides like the second contact (7 ) is also central, the surfaces of the two pads (2) and (3) between the first (4) and (5) and the central (6) and (7) as well as between the central (6) and (7) and the third (8) and (9) accounts kts are covered with a thin dielectric layer (10) of constant thickness, on which metal gate electrodes are formed - from left to right first (11) and second (12) for the first pad (2), and third (13) and fourth ( 14) for the second (3), the first (11) and the second (12) gate electrode are simultaneously connected to contact (7) on the pad (3), and the third (13) and fourth (14) gate electrode are simultaneously connected to contact (6) on pad (2), the third contacts (8) and (9) are connected, and the first (4) and (5) are connected to the terminals of the current source (1) as contacts (6) and (7) are the differential output (15) of element. provides a more detailed definition of the topology of magnetic induction in 16. The unexpected positive result of the new technical solution is that a non-standard approach to increase sensitivity is used in Hall sensors - the field effect typical of MOS transistors. Through this method, the Hall potentials +^ ₆ and _{-φ Ί themselves} are used to generate additional uncompensated charges of opposite sign to those of the Lorentz deviation F _L j on the corresponding parts of the upper surfaces of the element. An important feature is that the magneto-sensitive element is implemented in a single technological cycle, without requiring additional complicating processes for forming the load resistors on the silicon chip, which is an important advantage. The planar magnetosensitive element can be implemented with CMOS or BiCMOS technologies, with the configuration's conversion zones representing deep i-type pockets 2 and 3 in a p-type substrate. The integrated technology allows the new element together with the signal processing V _O ut(F) 15 circuitry to be implemented on a common silicon chip, forming an intelligent microsystem (MEMS). The operation of the proposed planar magnetosensitive converter is in a wide temperature range, including at cryogenic temperatures. For even higher sensitivity for weak-field magnetometry and counter-terrorism purposes, the chip can be sandwiched between two identical oblong B 15 ferrite or μ-metal magnetic field concentrators.