BG112385A - DUAL MICROSCENER FOR MAGNETIC FIELD - Google Patents

Abstract

The two-axis magnetic field microsensor comprises a p-type semiconductor pad (1) on which a deep n-type layer (2) is formed in the form of a Maltese equally strange cross with four equal rectangular sides. At the short sides of the n-layer (2) are located ohmic contacts - first (3), second (4), third (5) and fourth 6 as (3) and (5) are the opposite. The contact resistors (7) and (8) are connected via the resistors (10) and (11) to the contacts of the current source (9) and the contacts (5) with value as the other two (7) and (8) are connected to the current source (9) so that the polarity of contacts (3) and (5) and respectively of (4) and (6) coincide. The measured outer magnetic field (12) is of random orientation and lies in the plane of the pad (1) with the pairs of contacts - (3) and (5), respectively (4) and (6) for the two orthogonal plane components of the magnetic field vector (12).

Description

(54) TWO-AXIS MICRO-SENSOR FOR MAGNETIC BULLETS equal rectangular sides. On the short sides of the η - layer (2) are located ohmic contacts - first (3), second (4), third (5) and fourth 6 as (3) and (5), and respectively (4) and (6) are opposite. Contacts (3) and (4) through equal value load resistors (7) and (8) are connected to the terminals of the current source (9), and contacts (5) and (6) through load resistors (10) and (11) with a value as the other two (7) and (8) are connected to the current source (9) so that the polarities of contacts (3) and (5), and (4) and (6), respectively. The measured external magnetic field (12) has an arbitrary orientation and lies in the plane of the pad (1) as the pairs of contacts - (3) and (5), and respectively (4) and (6) are the outputs (13) and (14) for the two orthogonal plane components of the magnetic field vector (12).

claim, 1 figure

Siya Valcheva Lozanova Chavdar Stanoev Rumenin

Sofia

TWO-AXIS MICRO-SENSOR FOR MAGNETIC FIELD

FIELD OF THE INVENTION

The invention relates to a two-axis microsensor for magnetic field, applicable in the field of non-contact measurement of angular and linear displacements, positioning of objects in the plane, robotics and mechatronics, low-field magnetometry, cognitive systems and automation, electrical engineering, control, measurement technology energy and energy efficiency, military affairs and security, etc.

BACKGROUND OF THE INVENTION

A biaxial microsensor for magnetic field is known, containing / z-type semiconductor substrate, on one side of which are formed a central ohmic contact with a square shape as at distances and symmetrically with respect to its four sides there is one rectangular inner ohmic contact and one outer ohmic contact. A deep surrounding // - type zone is formed near all contacts. The four external contacts are connected and connected to the central contact via a power source. The measured external magnetic field has an arbitrary orientation and lies in the plane of the n-type substrate as each pair of opposite internal contacts relative to the central one are the outputs for the two orthogonal plane components of the magnetic field vector, [1 - 6].

A disadvantage of this two-axis microsensor for magnetic field is the reduced sensitivity of the two sensor outputs when measuring the planar components of the magnetic field as a result of the volumetric flow of the four supply currents between the central and end ohmic contacts.

Another disadvantage is the reduced accuracy of the microsensor as a result of parasitic output voltages at both outputs (offsets) in the absence of a magnetic field caused by electric asymmetry due to geometric asymmetry in the location of internal and external contacts relative to the central, inevitable technological imperfections when enclosing the chip, etc.

Another disadvantage is the complicated construction, containing nine ohmic contacts, which significantly increases the dimensions of the structure and reduces its resolution (resolution) and makes it difficult to implement the microsensor.

TECHNICAL ESSENCE

It is an object of the invention to provide a two-axis microsensor for a magnetic field with high magnetic sensitivity, increased measuring accuracy of the two sensor channels and a simplified construction by reducing the number of ohmic contacts.

This problem is solved with a two-axis microsensor for a magnetic field, containing a p-type semiconductor substrate, on one side of which is formed a deep / z-type layer in the form of a Maltese cross with four equal rectangular sides (equilateral cross). On the short sides of the n - type layer there is respectively one ohmic contact - first, second, third and fourth as the first and third, and respectively the second and fourth are opposite. The first and second contacts through the same value load resistors are connected to the terminals of the current source, and the third and fourth through the load resistors with the same value as the other two resistors are connected to the current source so that the polarities of the first and third and second and fourth contacts to match. The measured external magnetic field is of arbitrary orientation and lies in the plane of the p-type substrate as the pairs of opposite contacts first and third, and respectively second and fourth are the outputs for the two orthogonal plane components of the magnetic field vector.

An advantage of the invention is the high magnetic sensitivity of the two sensor channels as a result of the removed leakage of the supply current components from the deep p-type epitaxial layer formed in the p-substrate.

Another advantage is the high measuring accuracy of the two sensor channels due to the drastically reduced parasitic influence between the components of the supply current through the n-type layer and the ability to reset the offsets of both outputs by changing the values of the four load resistors.

Another advantage is the significantly simplified instrument design of the two-axis magnetic field microsensor, containing only four instead of nine contacts.

Another advantage is the need for a special arrangement in a fixed coordinate system of the microsensor with respect to the source of the magnetic field due to the improved orthogonality of the two parts of the i-layer in the form of a cross as a result of the precision of microelectronic technology.

DESCRIPTION OF THE ATTACHED FIGURES

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

EXAMPLES OF IMPLEMENTATION

The biaxial microsensor for the magnetic field contains a p-type semiconductor substrate 1, on one side of which is formed a deep / 7-type layer 2 in the form of a Maltese cross with four equal rectangular sides (equilateral cross). On the short sides of the and - layer 2 there is respectively one ohmic contact - first 3, second 4, third 5 and fourth 6 as the first 3 and the third 5, and respectively the second 4 and the fourth 6 are opposite. The first 3 and the second 4 contacts through the same value load resistors 7 and 8 are connected to the terminals of the current source 9, and the third 5 and the fourth 6 through the load resistors 10 and 11 with a value as the other two 7 and 8 are connected to the current source 9, that the polarities of the first 3 and third 5, and of the second 4 and fourth 6 contacts, respectively, coincide. The measured external magnetic field 12 is of arbitrary orientation and lies in the plane of the p-type substrate 1 as the pairs of opposite contacts - the first 3 and the third 5, and respectively the second 4 and the fourth 6 are the outputs 13 and 14 for the two orthogonal plane components of the vector. the magnetic field 12.

The operation of the biaxial magnetic field microsensor according to the invention is as follows.

When contacts 3 and 4 are connected, and respectively 5 and 6 to the current source 9, four equal and two in two opposite directions current components / ₃ and - Is, and respectively / ₄ and - 1 ₆ flow. This specific feature is due to the connection of contacts 3, 4, 5 and 6 through the same load resistors 7, 8, 10 and 11 to the current source 9 in such a way that the currents between the opposite contacts 3 and 5, and respectively 4 and 6 are opposite directed relative to the center of the c-type epitaxial layer 2. Since the values of the load resistors 7, 8, 10 and 11 are many times greater than the internal resistance of the individual sections of the p-type symmetrical cross 2, the mode of operation of the microsensor is a generator of current. The created deep epitaxial i-layer 2 in the form of an equilateral (Maltese) cross uniquely limits the areas in which the current components / ₃ and - / 5 flow, and C and -1 _{6, respectively} . Thus, the parasitic volumetric and surface leakage of the supply current is eliminated. The trajectories of the components / ₃ and -1 ₅ , and respectively / ₄ and / b in the areas below the ohmic contacts 3 and 5 as 4 and 6 in the absence of a magnetic field 12 B (B _XJ B _y ) = 0 are initially perpendicular to the upper surface on the substrate 1. The reason is that the low-resistance contacts 3, 4, 5 and 6 represent equipotential current planes. Therefore, the currents penetrate significantly into the volume of the p-layer 2. Then the effective trajectories 1 ₃ and -1 ₅ , and respectively C and -1 ₆ in the volume of the p-layer 2 become almost parallel to its upper surface. This topology of current trajectories, which is important for the operation of the microsensor, is dictated by the relatively deep cruciform n-layer and its small linear dimensions. If in the case of structural asymmetry there is an inequality of these currents, their equalization is done by trimming a corresponding change in the values of the load resistors 7, 8, 10 or 11. Thus the inevitable offsets V _i3 (0) and Vi ₄ (0) of the differential outputs 13 and 14 in the absence of a magnetic field B 12 (B = 0) are easily compensated (reset).

The external magnetic field B 12, which lies in the plane of the substrate 1 and is of arbitrary orientation, through its two mutually perpendicular components B _x and B _y generates corresponding laterally deflecting moving current carriers Lorentz forces -Pm = ^ V _dr x B, where q is the elementary load of the electron, and V _dr is the vector of the average drift velocity of the moving current carriers, in our case the electrons in the p-layer 2. As a result of the Lorentz deflections F _{L> i the} trajectories in their separate parts - under contacts 3, 4 , 5 and 6 and between them for each of the oppositely directed current components Li- 1 ₅ , and respectively Ц and - 1 _{6 are} simultaneously deformed by “shrinking” and / or “expanding”. Depending on the direction of the magnetic vector B 12, each in the pairs of opposite currents increases or decreases. Due to the operating mode of the current generator / ₃ = -1 ₅ = Ц = - / ₆ = const, instead of changes of the individual current components through contacts 3 and 5, and respectively 4 and 6, opposite sign Hall potentials are generated. Thus, through the Hall effect on the two differential outputs 13 and 14, Hall voltages arise: F ₃ , 5 (B _x ) = V] ₃ (B _X ) 13 and Y ₄ , b (B _y ) = UnC-Wu) 14. The output signals 13 and 14 are linear and odd functions of the magnetic vectors B _x and B _y and contain metrological information. The increase in the magnetic sensitivity is due to the limitations in the substrate 1 of the epitaxial n-layer 2 through technological implementation. This original approach eliminates leakage of supply current. Also, the mutually perpendicular sides of the cross significantly improve the orthogonality of the current components I ₃ , - Is, / ₄ and - / _{6 with} respect to the two planar vectors B _x and B _y of the magnetic field B 12. Perfectly bounded in the p-type substrate 1 cruciform active zone 2 maximally reduces the parasitic mutual influence of the two sensor channels B _x and B _y . Therefore, as a result, the magnetic sensitivity and metrological accuracy increase. The absolute value of the vector of the magnetic field B 13 in the plane x-y of the substrate 1 and the angle Θ of the field B 14 with respect to a fixed reference axis in the same plane are given by the well-known expressions: | = (B _x + B _y ² ) ^1/2 and Θ = tanXv / B _y )! V, (B,)).

Through the proposed innovative design, a drastic simplification of vector magnetometers has been achieved for the first time. The data for the two orthogonal components B _x and B _y of the vector B 12 are obtained with only four 3, 4, 5 and 6, instead of nine ohmic contacts as in the known solution. The analysis of the operation of this unusual and maximally simplified 2D microsensor shows that its power supply and architecture form a virtual ohmic contact (source) in the central zone of the p-epitaxial cross.

The unexpected positive effect of the new technical solution lies in the innovative instrument design containing only four ohmic contacts 3, 4, 5 and 6, the current-limiting epitaxial p-layer 2, and the original inclusion of the pairs of contacts 3 and 5, and 4 respectively. and 6 to the current source 9, providing oppositely directed current components generating the two output voltages of Hall V ₁₃ (B _X ) 13 and Y ₁₄ (B _y ) 14.

This 2D magnetometer can be realized by various modifications of the planar silicon technology - CMOS, BiCMOS, SOS, and if necessary micromachining silicon processes can be used.

Claims (6)

[1] Ch.S. Roumenin, “Solid State Magnetic Sensors”, Elsevier, Amsterdam, 1994, p. 450; ISBN: 0 444 89401. [2] R. Popovic, “Integrated Hall element”, U.S. Patent 4,782,375 / November 1, 1988. [3] F. Burger, P.-A. Besse, R.S. Popovic, “New fully integrated 3-D silicon Hall sensor for precise angular-position measurements”, Sensors and Actuators, A 67 (1998) pp. 72-76. [4] M. Paranjape, L.M. Landsberger, M. Kahrizi, “A CMOS-compatible 2-D vertical Hall magnetic-field sensor using active carrier confinement and postprocess micromachining”, Sensors and Actuators, A 53 (1996) 278 -283. [5] Ch.S 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. [6] RS Popovic, “The vertical Hall-effect device”, IEEE Electron Device Lett., EDL-5 (1984), pp. 357-358.