BG67386B1 - Integrated hall effect sensor with an in-plane sensitivity - Google Patents

Abstract

The integrated Hall sensor with an in-plane sensitivity comprises two semiconductor wafers of an n-type conductivity, arranged in parallel - first (1) and second (2), and a current source (3). On one side of the wafers (1 and 2) are formed in series from left to right five and respectively three ohmic rectangular contacts, parallel to their long sides - first (4), second (5), third (6), fourth (7) and fifth (8) on wafer (1), and first (9), second (10) and third (11) of the second (2) wafer. Contact (6) of the first (1) and contact (10) of the wafer (2) are central and relative to them the first (4) and the fifth (8), and respectively the second (5) and the fourth (7) contact of the wafer (1), as the first (9) and third (11) contacts of the second (2) wafer are arranged symmetrically. Close to the two long sides of the contacts (6 and 10), in parallel and at equal distances from them, there is a deep zone (12) with p-type conductivity, the length of which is equal to that of the contacts (6 and 10). The two terminals of the current source (3) are connected to the contacts (6 and 10). The first contact (4) of wafer (1) is connected to the contact (9) of the second (2) one, and the fifth contact (8) of the first (1) wafer is connected to contact (11) of the wafer (2). The first (4) and fourth (7) contacts, and respectively the second (5) and fifth (8) contacts of the wafer (1) are connected. The differential output (13) of the sensor is the first (9) and third (11) contact of the wafer (2), and the measured magnetic field (14) is parallel to both the planes of the wafers (1 and 2) and the long sides of the contacts (4, 5, 6, 7, 8, 9, 10 and 11).

Description

(54) INTEGRAL HALL SENSOR WITH PLANE SENSITIVITY

Field of technique

The invention relates to an integral Hall sensor with planar sensitivity, applicable in the field of sensors; robotics and mechatronics including robotic and minimally invasive surgery; biomedicine; quantum communication; artificial intelligence security systems and military affairs; electric cars and hybrid vehicles; unmanned aerial vehicles; mechanical engineering and production automation; non-contact measurement of angular and linear displacements; weak-field magnetometry; energy; counter-terrorism including underwater, land and air surveillance and prevention; navigation etc.

Prior art

An integral Hall sensor with planar sensitivity is known, containing two identical semiconductor substrates with n-type impurity conductivity - first and second, located in parallel and a current source. Five rectangular ohmic contacts parallel to their long sides - first, second, third, fourth and fifth - are formed on one side of each of the pads successively from left to right and at equal distances. The first and fifth, and respectively the second and fourth contacts are symmetrical with respect to the third. The first and fifth contacts are interconnected. The second contact of the first pad is connected to the fourth of the second, and the fourth contact of the first pad to the second contact of the second. The two terminals of the current source are connected to the second and fourth contacts of the first pad. The differential output of the Hall sensor is the two central contacts, and the measured magnetic field is parallel, both to the planes of the pads and to the long sides of the contacts, [1-7].

A disadvantage of this integral Hall sensor with planar sensitivity is the low conversion efficiency (magnetosensitivity) due to the input and output contact pads being planar on the same surface, with the supply current flowing mostly horizontally. The action of the magnetic field through the deflecting Lorentz force on the horizontal current is negligible and the sensitivity is generated by the vertical component of the current.

A disadvantage is also the complicated construction of the sensor, containing ten contacts with a total of four connections between them, which limit the technological implementation through integral microelectronic processes.

A disadvantage is the reduced measurement accuracy due to the low sensitivity and the increased level of the own 1/f (flicker) noise from the passage of the horizontal component of the supply current through the output Hall contacts.

Technical essence of the invention

The task of the invention is to create an integral Hall sensor with planar sensitivity, which has high conversion efficiency (magnetosensitivity), simplified construction by reducing the number of contacts and connections between them, and increased measurement accuracy by reducing the inherent 1/f noise .

This task is solved with an integral Hall sensor with planar sensitivity, containing two semiconductor substrates with n-type impurity conductivity, located in parallel - first and second, and a current source. On one side of each pad, five and three ohmic rectangular contacts are formed sequentially from left to right, parallel to their long sides - first, second, third, fourth and fifth on the first pad, and first, second and third on the second. The third contact of the first and the second contact of the second pad are central, and relative to them the first and fifth, and respectively the second and fourth contacts of the first pad, as well as the first and third contact of the second are located symmetrically. Near the two long sides of the central contacts, parallel and equidistant from them, there is a deep zone of p-type impurity conductivity, the length of which is equal to that of the third contacts. The two terminals of the current source are connected to the central contacts. The first contact of the first pad is connected to the first contact of the second, and the fifth contact of the first is connected to the third contact of the second pad. The first and fourth and second and fifth contacts of the first pad, respectively, are connected. The differential output of the Hall sensor is the first and third contacts of the second pad, and the measured magnetic field is parallel to both the planes of the pads and the long sides of the contacts.

An advantage of the invention is the increased magnetosensitivity as a result of: 1. the greatly reduced horizontal components of the supply current in both pads from the formed deep p-type zones on the long sides of the central contacts, determining the penetration of the supply current deep into the volume of the structures and contributing to dominance of the magnetically controlled vertical components; 2. the closely located first and second, and respectively the fourth and fifth contacts of the first pad through their connection unite the significant co-directional changes in the magnetic field of the vertical current components generated by their Lorentz deviation.

An advantage is also the simplified structure of the Hall sensor, containing a total of eight instead of ten ohmic contacts, which helps the technological implementation.

An advantage is the further reduced 1/f flicker noise due to the sensor design containing deep p-type gate regions equal in length to the center contacts, which drastically reduces the horizontal current components so that they do not pass through the output contacts.

An additional advantage is the increased resolution when measuring the minimum magnetic induction as a result of the increased signal-to-noise ratio through high sensitivity and reduced flicker noise.

An advantage is also the high measurement accuracy as a result of the increased sensitivity and the reduced 1/f noise from the removed passage of the horizontal components of the supply current through the contacts.

An advantage is also the minimized parasitic offset of the output through the immediate connections of the pairs of contacts on the first pad, compensating inevitable parasitic potentials and improving electrical symmetry with respect to the output.

An advantage is also the increased stability of the output voltage to temperature fluctuations due to the operation of the Hall sensor in the current generator mode formed by the internal resistances of the pads.

Explanation of the attached figure

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

Example of implementation of the invention

The integral Hall sensor with planar sensitivity contains two semiconductor pads with n-type impurity conductivity located in parallel - the first 1 and the second 2, and a current source 3. On one side of the pads 1 and 2, five and three ohmic resistors are formed sequentially from left to right rectangular contacts parallel to their long sides - first 4, second 5, third 6, fourth 7 and fifth 8 on the first pad 1, and first 9, second 10 and third 11 on the second 2. The third contact 6 on the first 1 and the second contact 10 of the second pad 2 are central and relative to them the first 4 and the fifth 8, and respectively the second 5 and the fourth 7 contact of the first pad 1 as well as the first 9 and the third 11 contact of the second 2 are located symmetrically. Near the two long sides of the central contacts 6 and 10, parallel and at equal distances from them, there is one deep zone 12 with p-type impurity conductivity, the length of which is equal to that of contacts 6 and 10. The two terminals of the current source 3 are connected to the central contacts 6 and 10. The first contact 4 of the first pad 1 is connected to the first contact 9 of the second 2, and the fifth contact 8 of the first 1 is connected to the third contact 11 of the second pad 2. The first 4 and the fourth 7 contact , and respectively the second 5 and fifth 8 contacts of the first pad 1 are connected. The differential output 13 of the Hall sensor is the first 9 and the third 11 contact of the second pad 2, and the measured magnetic field 14 is parallel, both to the planes of the pads 1 and 2, and to the long sides of the contacts 4, 5, 6, 7 , 8, 9, 10 and 11.

The operation of the integral Hall sensor with planar sensitivity according to the invention is as follows. When connecting the central contacts 6 and 10 to the current source 3, and connecting electrodes 4 with 9, 8 with 11, 4 with 7, and 5 with 8 according to Figure 1, the currents I ₆ , ₄ flow in the volumes of the two pads 1 and 2 , Ie,5 and -I ₆ , ₇ , -I ₆ , ₈ , and respectively 1ю,9 and -Ιιο,ιι. Due to the symmetry of structures 1 and 2 with respect to contacts 6 and 10, and the method of connection, these current components are equal and oppositely directed. The trajectories of the electrons in pads 1 and 2 are curvilinear, since in the absence of a magnetic field B 14 the ohmic planar contacts 4, 5, 6, 7, 8, 9, 10 and 11 through which the supply current components flow are equipotential planes. That is why the current lines are initially perpendicular to the upper surfaces of pads 1 and 2, then change their direction and in a certain section in their volumes are parallel to the upper planes. In addition, the deep p-type enclosure zones 12, equal in length to the rectangular central contacts 6 and 10, do not allow the presence of horizontal current components on the surface of the structures 1 and 2. Typically, according to the silicon technology used, the depth of the p-zones 12 varies up to about 12-15 μm. As a result, the penetration depth w of the current lines at a fixed concentration of the doping donor impurity ND in n-type Si substrates 1 and 2 also depends on the ratio M between the width 11 of contacts 4, 5, 6, 7, 8, 9, 10 and 11, and the distances 1 ₂ between them, M = 11/1 ₂ , [1, 2, 5 - 7]. The maximum depth w at the most commonly used in microelectronics concentration of doping donor impurities N _D ~ 10 ¹⁵ cm ³ in Si and contact width up to about 5-10 μm constitutes about w ~ 30-40 μm. At the same time, pad 2 with contacts 9, 10 and 11 represents the first planar-sensitive Hall microsensor with three ohmic contacts. This class of elements was created and developed by Rumenin and Lozanova, [5, 8 - 10]. The load resistors that are included in the end electrodes 9 and 11 of these microsensors, [8], in the new solution of Figure 1 are replaced by the internal resistances R ₉ , ₁₀ , R ₁₀ ,n, R4, ₆ and R ₆ , ₈ of the two pads 1 and 2. These resistors determine the operating mode of the current generator. The resistances R ₉ , ₁₀ , = R ₁₀ ,n, and R4, ₆ = R ₆ , ₈ are the same due to the structural symmetry of pads 1 and 2 with respect to contacts 10 and 6. Usually at the differential output V _H (B) = V ₉ , ₁₁ (B) 13, formed by contacts 9 and 11, in the absence of an external magnetic field B 14, B = 0, there is a parasitic voltage or offset unrelated to the magnetic induction. Its minimization in our case is achieved by the innovative solution from Figure 1. The direct connections of the pairs of contacts 4 - 7 and 5 - 8 shorten the parasitic offset potentials in structures 1 and 2 relative to the potentials of output contacts 9 and 11 by the flow of equalizing currents. Such possibility is absent in the known decision.

The current generator mode, which occurs simultaneously for both structures 1 and 2, stabilizes the temperature drift at the output 13 of the sensor from the influence of the temperature T. This is due to the clearly regulated influence of the temperature T in such an operating mode on the kinetic and galvanomagnetic processes in semiconductors structures, [5].

In the presence of an external magnetic field B 14, in pads 1 and 2 forming the integral sensor and representing a five-contact and three-contact Hall element, the current components I ₆ , ₄ , 16.5 -I ₆ , ₇ , -I6, ₈ and respectively I ₁₀ , ₉ and -1ju,c are subjected to the deflecting lateral action of the Lorentz forces F _L j [1, 2, 5 - 10]. The topology of the current lines as a result of the originally modified instrument structure 1 is mainly vertical in the areas of contacts 4 and 5 as well as 7 and 8. At the same time, the pairs of electrodes 4 - 5 and 7 - 8 are located sufficiently close to each other. That is why the Lorentz deviation of the current lines, depending on the polarities of the current source E _s 3 and the magnetic field B 14, leads to a significant change in the currents through the contacts. For example, components - ΔI ₄ (B) and -ΔΙ ₇ (Β) decrease, and components + ΔI ₅ (B) and + ΔI ₈ (B) increase. The change in these currents is of the same value. Therefore, by connecting contacts 4 - 7 and 5 - 8, the significant co-directional changes in magnetic field B 14 of the current components through them are combined. The situation is similar for configuration 2 with the currents through contacts 9 and 11 in field B 14. Through the load resistors R ₉ , ₁₀ , R ₁₀ , ₁₁ , R4,6 and R6, ₈ the changes in the Hall currents are transformed into a change in the output voltage Vh(B) = V ₉ , ₁₁ (V). Therefore, the solution of Figure 1 leads to a substantial increase in the magnetic sensitivity of the sensor. The new configuration has a simplified design. It contains eight contacts and a reduced number of connections, which facilitates its technological implementation. The drastic minimization of the horizontal magnetically uncontrolled current components in both pads 1 and 2 reduces their passage through the output contacts 4 and 5 and 7 and 8. Therefore, the inherent 1/f noise is reduced. To reduce it, it is no longer necessary to apply the current spinning method [1, 6, 7], which requires additional circuit resources, an increase in the effective area of the chip and additional consumption of power supply, and the released heat leads to a deterioration of the metrological quality of the output signal. Simultaneously with the increased magnetic sensitivity and increased signal-to-noise ratio, the resolution in detecting the minimum magnetic induction Bmin, which is a key feature for the purposes of weak-field magnetometry, also increases. On the other hand, accuracy increases due to the synergy of high sensitivity, reduced parasitic offset, reduced noise and output temperature stabilization 13.

The unexpected positive effect of the new technical solution lies in the original design, the non-standard connection of contacts 4 with 7 and 5 with 8, as well as their close location. Only by modifying the instrument design and without using additional circuit approaches, high sensitivity and signal-to-noise ratio have been achieved, offset and temperature drift have been reduced, and metrological accuracy has been increased.

The integrated Hall sensor is implemented with CMOS, BiCMOS or micromachining microelectronic technologies, with the two conversion areas of the five-pin and three-pin elements 1 and 2 being deep n-type silicon pockets in p-type pads. Ohmic contacts 4, 5, 6, 7, 8, 9, 10 and 11 represent heavily doped n ⁺ regions, formed most often by epitaxy. The Hall microsensor can operate over a wide temperature range, including cryogenic environments, which dramatically increases sensitivity and reduces noise, improving overall performance in applications. For even higher conversion efficiency for weak-field magnetometry, counter-terrorism and navigation purposes, the chip with pads (eg n-type silicon pockets) 1 and 2 can be located between two identical field concentrators B 14 of ferrite or μmetal. The new sensor solution is the basis for building highly sensitive 2D and 3D magnetometers.

Claims (1)

Integral Hall sensor with plane sensitivity, containing two semiconductor pads with n-type impurity conductivity, located in parallel - first and second, and a current source, on one side of the first pad are formed in series from left to right five ohmic rectangular contacts parallel to their long sides - first, second, third, fourth and fifth, the third contact of the first pad is central, with respect to it the first and fifth, and respectively the second and fourth contacts are located symmetrically, the measured magnetic field is parallel to both the planes of the pads and and on the long sides of the contacts, characterized in that on one side of the second pad (2) there are three ohmic rectangular contacts in series from left to right, parallel to their long sides - first (9), second (10) and third 11) the second (10) being central and the first (9) and third (11) contacts being located symmetrically with respect to it, close to the two long sides of contacts (6) and (10), parallel and at equal distances from them there is a deep zone (12) with p-type impurity conductivity, the length of which is equal to that of contacts (6) and (10), the two terminals of the current source (3) are connected to the central contacts (6) and (10), the first contact (4) of the first pad (1) is connected to the first contact (9) of the second (2), and the fifth contact (8) of the first (1) is connected to the third contact ( 11) on the second pad (2), the first (4) and the fourth (7) contact, and respectively the second (5) and the fifth (8) contact of the first pad (1) are connected, as the differential output (13) of the sensor of Living room are the first (9) and third (11) contact of the pad (2)