BG67772B1 - TWO-AXIS INTEGRAL HALL SENSOR - Google Patents

Abstract

The two-axis integral Hall sensor, measuring the two planar components of the magnetic field, contains a direct current source (1) and a semiconductor substrate (2) with p-type impurity conductivity. On one side of it is embedded a square ring (3) of the same semiconductor with n-type conductivity, dividing the near-surface region of the p-type substrate (2) into an outer and inner square part. In the sector of one of the vertices of the ring (3) there is a narrow p-type zone (4), connecting the outer and inner parts of the near-surface region of the substrate (2). In the middles of the four sides of the ring (3) one ohmic contact (5, 6, 7 and 8) is formed. Near the two sides of the narrow p-zone (4), in the ring (3) one more ohmic power contact (9 and 10) are added, connected to the terminals of the current source (1). The measured magnetic field (11) is in the plane of the substrate (2) and is of arbitrary orientation. The pairs of opposite contacts (5 and 7), and respectively (6 and 8) in the ring (3) are the differential outputs (12 and 13) for the two orthogonal planar components of the magnetic field (11).

Description

Field of technology

The invention relates to a two-axis integral Hall sensor, applicable in the field of robotics and mechatronics; control and measurement technology; medicine, including robotic and minimally invasive surgery; navigation; low-field and high-precision magnetometry; automation, including contactless automation; 2-D positioning of objects in the plane; energy; automotive industry and electric vehicle construction; remote measurement of angular and linear displacements; military and security - ground, air and underwater surveillance and prevention systems; counterterrorism, etc.

Prior art

A two-axis integral Hall sensor is known, measuring simultaneously the two planar components of the magnetic field, containing an n-type semiconductor (silicon) square substrate, on one side of which a central ohmic contact with a square shape is formed. At distances and symmetrically with respect to its four sides, there is successively one rectangular inner ohmic contact and one rectangular outer ohmic contact. The four outer contacts are connected and through a power supply voltage source are connected to the central contact. The measured magnetic field is in the plane of the substrate and has an arbitrary orientation. The pairs of inner contacts opposite to the central one are the outputs for the two orthogonal planar components of the magnetic field, [1-8].

A disadvantage of this two-axis integral Hall sensor is the reduced sensitivity of both outputs due to surface current leakage originating from the separate power supply current components between the central and end contacts and leading to incomplete generation of the corresponding Hall potentials and voltages forming the metrological information of the two channels.

Another disadvantage is the low measurement accuracy resulting from the parasitic inter-channel influence of the surface current, which reduces the Hall voltages when measuring the two orthogonal magnetic components.

Technical essence of the invention

The task of the invention is to create a two-axis integral Hall sensor with high sensitivity and high measurement accuracy of both output channels.

This problem is solved with a two-axis integral Hall sensor, measuring simultaneously the two planar components of the magnetic field, containing a DC source and a semiconductor substrate with p-type impurity conductivity. On one side of it is embedded a square ring of the same semiconductor with n-type conductivity, dividing the near-surface region of the p-type substrate into an outer and inner square part. In the sector of one of the vertices of the ring there is a narrow p-type zone, connecting the outer and inner parts of the near-surface region of the p-type substrate. One ohmic contact is formed along the centers of the four sides of the embedded n-ring. Near the two sides of the narrow p-zone, one more ohmic power contact is added to the ring, connected to the terminals of the DC source. The measured magnetic field is in the plane of the substrate and has an arbitrary orientation. The pairs of opposing ohmic contacts in the n-type ring are the differential outputs for the two orthogonal planar components of the magnetic field.

An advantage of the invention is the high magnetic sensitivity of the two sensor channels, due to the generation of full Hall potentials, respectively Hall voltages, from the common supply current in the square ring as a result of the drastically reduced surface leakage of the currents in the sensor vector configuration.

Another advantage is the high measurement accuracy of the two sensor outputs, as there is no mutual inter-channel influence as a result of the well-localized components of the supply current in the n-type ring, generating Hall voltages only from the corresponding orthogonal components of the magnetic field.

Another advantage is the simplified design of the biaxial configuration, containing a total of six contacts and a single supply current, instead of nine electrodes and four separately formed current components of the known solution. Thus, no additional contacts and connections between them are required to redirect the current in the necessary orthogonal to the magnetic field directions. The sensitivity in our case is generated by the interaction in a magnetic field of the opposite pairs of output contacts with the single current trajectory.

Explanation of the attached figure

The invention is explained in more detail with an exemplary embodiment thereof, given in the attached figure 1, representing a plan of the two-axis sensor configuration.

Examples of implementation of the invention

The two-axis integral Hall sensor, measuring the two planar components of the magnetic field, contains a direct current source 1 and a semiconductor substrate 2 with p-type impurity conductivity. On one side of it is embedded a square ring 3 of the same semiconductor with n-type conductivity, dividing the near-surface region of the p-type substrate 2 into an outer and inner square part. In the sector of one of the vertices of the ring 3 there is a narrow p-type zone 4, connecting the outer and inner parts of the near-surface region of the p-type substrate 2. In the middles of the four sides of the ring 3, one ohmic contact 5, 6, 7 and 8 is formed. Near the two sides of the narrow p-zone 4, in the n-ring 3, one more ohmic power contact 9 and 10 are added, connected to the terminals of the current source 1. The measured magnetic field 11 is in the plane of the substrate 2 and has an arbitrary orientation. The pairs of opposite ohmic contacts 5 and 7, and respectively 6 and 8 in the n-type ring 3 are the differential outputs 12 and 13 for the two orthogonal planar components of the magnetic field 11.

The operation of the two-axis integral Hall sensor according to the invention is as follows. When the power contacts 9 and 10 are connected to the source 1, operating in the current generator mode, a single power supply current I1 flows in the n-type ring 3, consisting of four parts I5 = |-I ₇ | = I6 = |-I ₈ | = I1. The constant current generator 1,11 = const, forming the four equal components in the ring 3, determines the same flow conditions. The current lines 11, passing through the opposite electrodes 5, 7 and respectively 6, 8, have opposite directions. In fact, depending on the polarity of the power contacts 9 and 10, the current lines I1 circulate in the ring 3 clockwise or counterclockwise, ± 11. The four n-regions of the ring 3, forming a square, are precisely limited by the p-type substrate 2, eliminating the leakage of the power current 11 along the surface of the structure 2. The power contacts 9 and 10 are separated by the narrow p-type zone 4, preventing shunting of the current I1. In this way, the entire current I1 flows through the n ring 3. Thus, the structure of Figure 1 is simplified and contains only six contacts. The sector with the narrow p-type zone 4, connecting the outer and inner parts of the surface region of the substrate 2 is irrelevant at which vertex of the ring 3 it will be realized.

The measured magnetic field B 11 is in the x-y plane of the substrate 2 and is of arbitrary orientation. The two mutually perpendicular magnetic fields B _x and B _y act on the moving carriers of components I ₅ , -I ₇ , 1 ₆ and -I 8 through the Lorentz forces, F щ = qV ь х В, where q is the elementary charge of the electron, and Vdr is the vector of the average drift velocity of the electrons in the ring 3. Since the currents 15, -I 7, I 6 and -I 8 are limited, the deflecting action of the Lorentz forces F щ is maximally effective. As a result of the Lorentz deflection Fl in the thus formed n-type configuration 3 with square geometry, the trajectories of the oppositely directed components I 5 and I ₆ , for example, are “contracted” and -I ₇ and -I ₈ are “expanded”, respectively. In this process, the current carriers either “rise” to the surface of the ring 3, where the output contacts 5 and 6 are, or “fall” to its lower side, moving away from electrodes 7 and 8. In the first case, additional negative charges are generated on contacts 5 and 6 and the corresponding Hall potentials are negative, and in the second - contacts 7 and 8 acquire a positive potential. As a result, the Hall differential voltages Vi ₂ (B x) 12 and V13(B y) 13 are generated on the output terminals 5 and 7, and 6 and 8, respectively, i.e. the information indicators for the values and directions of the two orthogonal components B x and B y of the magnetic field vector B 11. In essence, the configuration of Figure 1 is a functional combination of four three-contact Hall elements with planar magnetosensitivity - the power electrodes 9 and 10, and each of the 3 contacts located in the middle parts of the square ring: 9-5-10; 9-6-10; 9-7-10 and 9-8-10, [1, 3, 4, 6, 8]. These three-contact sensors are activated by the planar components B _x and B _y . According to the action of the Hall effect, the output voltages V ₁₂ (B) 12 and V ₁₃ (B) 13 are linear and odd functions of the fields ± B x and ± B y, and of the current ±I1. The increased magnetic sensitivity is due to the 3 components I5, -I7, 16 and -I8 of the current I1 limited in the n-ring. This innovative approach eliminates the leakage of currents in the near-surface region. At the same time, the orthogonality of the corresponding current lines with respect to the two planar vectors B x and B y of the field B 11 is improved. Thus, the force Fl acts as effectively as possible on the individual parts of the trajectory I ₁ , generating through them maximum Hall potentials on contacts 5, 6, 7 and 8. The limitation of the currents in the sides of the square n-ring 3 reduces one of the significant disadvantages of vector magnetometry - the mutual inter-channel influence when measuring the magnetic fields Bx and By. Using a power supply in the current generator mode 1, and not a constant voltage as in the known solution, prevents a change in the current in the ring 3 from the field B 11. In addition, at current I ₁ = const, preservation of the magnetic susceptibility is achieved with a variation in temperature T. The absolute value of the field vector B 11 in the x -y plane and the angle Θ of the vector B 11 relative to a fixed reference axis in the same plane are given by the expressions: | B | = (Bx ² + B y ² ) ^1/2 and Θ = tan ^-1 ( Vy(B y)/( V,(Bx)), [1,8].

The unexpected positive effect of the new technical solution lies in the introduced narrow ring structure 3 and the single magnetosensitivity-generating current I ₁ . As a result, high conversion efficiency, increased measurement accuracy of the 2-D sensor and a simplified design are achieved.

The two-axis Hall sensor can be implemented with various modifications of the integrated silicon technology - CMOS, BiCMOS, SOS, and if necessary, micromachining silicon processes can be used. The optimal depth of the n-ring 3 is about 5-7 pm. The new 2-D magnetometer also functions in the cryogenic temperature range, as the current generator mode I ₁ = const preserves the magnetic sensitivity without using complex circuitry.

Claims (1)

1. A two-axis integral Hall sensor comprising a power source and a semiconductor substrate with ohmic contacts, the measured magnetic field being in the plane of the substrate and having an arbitrary orientation, characterised in that the power source (1) is a DC generator, the semiconductor substrate (2) has a p-type impurity conductivity, on one side of which a square ring (3) of the same semiconductor with n-type conductivity is embedded, dividing the near-surface region of the p-type substrate (2) into an outer and inner square part, in the sector of one of the vertices of the ring (3) there is a narrow p-type zone (4) connecting the outer and inner parts of the near-surface region of the p-type substrate (2), and in the middles of the four sides of the ring (3) one ohmic contact (5, 6, 7 and 8) is formed, in the vicinity of the two sides of the narrow p-zone (4), in the n-ring (3) one more ohmic power contact (9 and 10) is added, connected to the terminals of the current source (1), the pairs of opposite ohmic contacts (5 and 7), and respectively (6 and 8) in the ring (3) are the differential outputs (12 and 13) for the two orthogonal planar components of the magnetic field (11).