SU879521A1 - Hall generator - Google Patents

Description

(54) HALL SENSOR

i

The invention relates to a measurement technique, more specifically, to devices for measuring magnetic fields, based on the use of galvanic and magnetic effects.

Devices are known for measuring and converting magnetic fields into an electrical signal with use. eat galvanomagnetic effects - Hall sensors

These devices have weak mechanical strength due to low contact size and for the same reason they have low power dissipation in the operation mode without overheating, which limits the operating current through the converter, and hence its sensitivity to the magnetic field. And besides, these devices have a sensitivity to temperature changes, which leads to an additional measurement error.

Also known is a Hall sensor for 25 measurements of magnetic fields 2.

Famous Hall sensor containing a Hall element made of a semiconductor wafer located on a dielectric substrate, 30

current and potential electrodes and compensation resistance connected in parallel with or in series with potential electrodes. In the first case, this resistance has the same temperature coefficient as the Hall sensor, in the second - it has the opposite, compared to the Hall sensor, it has a thermal coefficient. Connection of additional resistance is used for temperature compensation.

The disadvantages of the known device are, firstly, the lack of accuracy, and secondly, the difficulty of selecting resistances with the same temperature coefficients. The purpose of the invention is to improve the accuracy of measurements.

In order to increase accuracy in the Hall sensor containing a dielectric substrate on which the Hall element is located, made of a semiconductor plate, current and potential electrodes, the length of the current electrodes is equal to the width of the semiconductor plate, and

The thickness of the semiconductor wafer is defined by the expression:

- (Ñ-ИО,)

,

0, 52-1

where d is the plate thickness, microns;

c is the coefficient determined by the concentration of current carriers;

cL is the temperature coefficient of the output voltage.

The drawing shows a schematic of the Hall sensor,

The Hall sensor contains a dielectric substrate 1, on which a semiconductor wafer is located. Hall Element 2 is formed from this plate, having Hall protrusions 3 and 4 on which potential electrodes are applied (not shown in the drawing). Current electrodes 5 and b are applied both to the working area of the Hall element 2 and to the non-working areas 7-10 of the semiconductor wafer.

The Hall sensor works in the usual manner. The current electrodes 5 and b are connected to a power source, and a signal proportional to the magnitude of the magnetic field is removed from the potential electrodes.

In order for the temperature coefficient of the output voltage to be minimal, the thickness of the semiconductor wafer is selected taking into account the expression:

geo-s / rrz95L

J

d io

OD1T

where d is the semiconductor thickness

plates) in - coefficient determined by

carrier concentration;

o is the temperature coefficient of the output voltage. For example, for indium antimonide, already at a carrier concentration of 710 cm, the temperature coefficient of the output voltage goes through zero. However, the thickness of the Hall element 2 in this case will be unreasonably large. Optimally used in the manufacture of Hall sensors is an antimonide indium with a current carrier concentration of 10 10 cm. The value in for this carrier concentration will be equal to 0.124. By substituting this value into the formula, one can determine the thickness of the Hall element to obtain any desired temperature coefficient of the output voltage of the Hall sensor.

For example, if it is required that this coefficient be equal to zero, then the thickness of the Hall element 2 is 52 microns.

When defining the shape of the Hall element f 2, the semiconductor substance is etched only along the contour of the element, so that the grooves separate the working area of the Hall element 2 from the non-working sections 7-10 of the semiconductor wafer. The current electrodes 5, 6 are applied both to the working and non-working portions of the semiconductor wafer, so that the length of the contacts is equal to the width of the entire semiconductor wafer.

5 Thus, due to the larger contact area of the current electrodes 5.6c with a semiconductor plate, the mechanical strength of the Hall sensor is increased and the power is increased,

0 discharged from the surface of the Hall element 2 through large-area current electrodes 5, 6, made, for example, from copper foil. In this case, the smaller the size of the Hall element 2,

with the greater the effect.

Using the detected dependence of the temperature coefficient of the output voltage on the thickness of the semiconductor wafer for different concentrations of current carriers, in the manufacture of Hall sensors, one can preselect a plate thickness that, for a given concentration of current carriers, will provide the necessary value of the temperature coefficient

5 output voltages.

Claims (2)

1.A. Kobus, J. Tushinsky. Hall sensor and magnetoresistors, M., 1971, 0 s. 101-106. 2. The patent of Germany No. 1104603, cl. 21 e 26/01. 7 j  f