RU2743625C1 - Magnetic field transducer with functionally integrated structure - Google Patents

Abstract

FIELD: magnetic fields.SUBSTANCE: invention relates to high-precision magnetic field sensors with a sensitivity of up to a fraction of nanotesla, the creation of such devices will expand the field of their application, especially in medicine. The design of the magnetic field transformer contains a horizontal bipolar n-p-n (p-n-p) transistor located on the substrate surface, containing a dielectric, a collector region and an emitter region of n (p) conductivity type, a base region of p (n) conductivity type, an electrode of the common bus is placed on the emitter region, on the base area - the control bus electrode, on the collector area - the output bus electrode, on the substrate surface there is also a power bus electrode, a load resistor connected, respectively, by the first terminal to the collector electrode, the second terminal to the power bus electrode, characterized in that the dielectric is located on the surface of the base region, on the surface of the dielectric there is an additional electrode of the control bus, which forms a functionally integrated structure of the MOS capacitor with the dielectric and the base region, while the resistance of the substrate forms a base resistor, and on the surface of the substrate there is a region of the additional collector n (p) of type pr flow, on the surface of which the power bus electrode is located.EFFECT: invention improves measurement accuracy and reduces energy consumption.1 cl, 13 dwg

Description

The invention relates to microelectronics and can be used to create various types of sensors, in particular a magnetic field.

Known analogues- semiconductor magnetic field sensors that use the deviations of the magnetic field of the trajectory of the diffusion motion of minority charge carriers (hereinafter PSMPD) [1. Kozlov AV, Korolev MA, Tikhonov R.D., Cheremisov AA, "Planar bipolar magnetotransistor", RF Patent 2439748; 2.R. Popovic, H.P. Bakes / Sensitive magnetotransistor magnetic field sensor // US Patent 4,700,211; 3. L.W. Davies, M.S. Wells Magneto - transistors incorporated in an IC // Proceding IREE Australia, 1971, no. 6, p. 235-238; 4. Kozlov A.V., Tikhonov R.D. "Semiconductor magnetic converter RF Patent 2284612]in the base of bipolar transistors.

The basis of the well-known structures of the PSMPD [1. Kozlov AV, Korolev MA, Tikhonov R.D., Cheremisov AA, "Planar bipolar magnetotransistor", RF Patent 2439748; 2. R. Popovic, H. P. Bakes / Sensitive magnetotransistor magnetic field sensor // US Patent 4,700,211; 3. L.W. Davies, M.S. Wells Magneto - transistors incorporated in an IC // Proceding IREE Australia, 1971, no. 6, p. 235-238; four. Kozlov A.V., Tikhonov R.D. "Semiconductor magnetic converter RF Patent 2284612] is a horizontal bipolar transistor located on the surface of the substrate, on areas emitter, collector and base whom the corresponding electrodes are placed, the structure also contains a dielectric and a load resistor.

The disadvantages of analogs are the need to convert the output signal, analog into a digital code, which significantly complicates their design and manufacturing technology, increases the energy consumption and reduces the accuracy of measuring the magnetic field.

These disadvantages are partially devoid of the closest, in technical essence, the design described in the patent [4. Kozlov A.V., Tikhonov R.D. "Semiconductor magnetic converter RF Patent 2284612], which is taken as a prototype. Its electrical circuit design and topology are shown respectively in figure 1, figure 2, figure 3.

The electrical circuit of the prototype contains an n-p-n (p-n-p) bipolar transistor, the emitter of which is connected to a common power bus, a base to a control bus, a collector to an output bus and through a load resistor to a power bus.

The design of the prototype shown in Fig. 2 is the design of a horizontal bipolar transistor located on the surface of the substrate, which contains a dielectric, collector and emitter regions of n (p) type of conductivity and a base region of p (n) type of conductivity, on the surface of which the corresponding electrodes are placed, that is, on the emitter area - the common bus electrode, on the base area - the control bus electrode, on the collector area - the output bus electrode, the power bus electrode and the load resistor. Figure 3 shows the topology of the prototype.

This device also has the disadvantages of an analog signal, time-consuming power consumption, and noise-limited magnetic field measurement accuracy.

The technical effect of the invention is to improve the measurement accuracy and reduce energy consumption.

These effects are achieved by:

The electrical circuit of the proposed PSMPD (figure 4) contains a two-collector n-p-n (p-n-p) bipolar transistor, the emitter of which is connected to a common power bus, the base is connected to the second terminal of the capacitor and the first terminal of the additional resistor, the second terminal of which , connected to the common bus, the first terminal of the capacitor is connected to the control bus, the first collector of the transistor is connected to the output bus and through the load resistor to the power bus, an additional resistor, the first terminal of which is connected to the common bus, and the second to the base of the transistor, and the second collector of the bipolar the transistor is connected to a common power bus.

The design of the PSMPD (Fig. 5), the topology (Fig. 6) contains a dielectric located on the surface of the base region, on the surface of which an additional electrode of the control bus is located forming a functionally integrated structure of the MOS capacitor with the dielectric and the base region, while the substrate resistance forms the base resistor , on the surface of the substrate there is also a region of an additional - second collector of n (p) type of conductivity, and on its surface there is a corresponding electrode of the second collector connected to the power bus.

Operating principle

The physical principle of operation of the prototype and the invention is similar and is based on the deviation of the trajectory of motion of electrons by a magnetic field (Lorentz's law).

This circumstance, in the presence of a magnetic field, leads to an increase in the distance of electrons passing from the emitter region to the collector region, i.e. to an increase in the effective thickness of the base of the transistor, and, accordingly, to a proportional decrease in the collector current of a horizontal bipolar transistor, since its value is related by a quadratic dependence with the effective thickness of the base of the transistor

I _k = I _b × β

where β = τ ₀ ∙ D _p / W _eff ²

where β is the gain of the transistor,

I _k - collector current,

I _b - base current;

τ ₀ is the lifetime of minority charge carriers;

D _p - diffusion coefficient;

W _eff - effective base thickness.

The principle of operation of the invention (see Fig. 7, Fig. 8) consists in applying to the input of the sensor (capacitor - C) a pulsed rectangular pulse voltage - a signal that is differentiated - R _d ∙ C by a chain. As a result, "short" negative and positive impulses are formed. In this case, a positive impulse (in the case of n - p - n) of a bipolar transistor) completely opens the transistor, to the deep saturation mode, in which it stays for a time - τ _n , which should exceed the recharge time of the input capacitance through an additional resistance R _d ∙ C :

τ _n = I _b ∙ L _n I _b (τ ₀ ∙ D _p / W _eff ² ) ∙ I _k

In this case, we have a dependence of the saturation time τ _n , which is easily and accurately measured on an oscilloscope on the effective base thickness, respectively, the magnetic field strength - B, i.e. τ _n = F (B).

It is important here that the sensitivity of the magnetic field sensor can be significantly improved if it is organized in the form of a series-connected pixel chain, in which the input of each pixel is connected to the output of the previous one (Fig. 7). In this case, the times of the sensor pixel signals are summed, while the sensor noise decreases in proportion to the square root of the number of pixels in the chain.

In this case, the power consumption of energy by the sensor practically does not depend on the number of its elements - a pixel.

The second additional PSMPD collector is designed to collect the "side signal" - minor carriers that do not participate in the formation of the output signal.

The electrical circuit of the invention is shown in figure 4, consists of a two-collector bipolar transistor, the base - 1 of which is connected through an additional resistance - 2 to the control bus - 8 and through a capacitor - 4 to the input bus - 5, its emitter - 6 is connected to the common bus - 3, the first collector - 11 is connected to the output bus - 7 and through the load resistor - 9 to the power bus - 10, the second collector is connected to the power bus - 10.

The design is shown in Fig. 5, and the topology in Fig. 6, which contains a two-collector horizontal bipolar transistor n-R-n (p-n-p) type, located on the surface of a lightly doped substrate - 13 p (n) type of conductivity, containing a dielectric - 14, regions of n (p) conductivity type, the first collector - 15 and the second additional collector - 16, emitter region - 17 n⁺ (R ⁺ ) type of conductivity and the base area - 18 p (n) type of conductivity on the emitter area - 19 there is an electrode of the common bus - 20, on the contact area of the base p⁺ type - 18 the electrode of the common bus is placed - 20, on the area of the first collector - the electrode of the output bus - 21 on the area of the additional second collector - the power bus electrode - 22, a load resistor - 23 is also placed on the surface of the substrate, connected respectively by the first terminal to the electrode of the first collector, the second to the power bus electrode - 24, while on the surface of the substrate area - 1, there is a thin dielectric - 25, and on its surface there is an additional electrode of the control bus - 26, which forms a functionally integrated structure of the MOS capacitor with the dielectric and the base area, while the substrate resistance - 13 forms the base resistor.

Manufacturing technology shown in Fig. 9, Fig. 10, Fig. 11,Fig. 12, Fig. 13.

An example of practical implementation is an electrical circuit of a pixel sensor chain, a prototype was experimentally investigated, which was assembled from KT315 silicon transistors, 0.1 μF capacitors and OMT resistances with 1 kΩ load and 22 kΩ additional.

Brief Description of Drawings

Fig. 1 Electrical diagram of the prototype.

Figure 2 Design of the prototype.

Fig. 3 Prototype topology.

Fig.4 Electrical diagram of the invention.

Fig. 5 Construction of the invention.

Fig. 6 Topology of the invention.

Fig. 7 Magnetic field transducer chain.

Fig. 8 Time dependences of the input and output pulse from time.

Fig.9 Formation of the reservoir by phosphorus diffusion.

Fig. 10 Formation of area contacts - ion doping with arsenic.

Fig. 11 MOS structure formation - fine oxidation.

Fig. 12 Formation of contacts.

Fig. 13 Deposition of Al.

Claims (1)

The design of the magnetic field transformer, containing a horizontal bipolar transistor npn (pnp), located on the surface of the substrate, containing a dielectric, a collector region and an emitter region of n (p) conductivity type, a base region of p (n) conductivity type, an electrode of the common bus is placed on the emitter region , on the base area - the control bus electrode, on the collector area - the output bus electrode, on the substrate surface there is also a power bus electrode, a load resistor connected, respectively, by the first terminal to the collector electrode, the second terminal to the power bus electrode, characterized in that the dielectric is located on the surface of the base region, on the surface of the dielectric there is an additional electrode of the control bus, which forms a functionally integrated structure of the MOS capacitor with the dielectric and the base region, while the substrate resistance forms the base resistor, and on the substrate surface there is an additional collector area of the n (p) type conductivity, on the surface of which the power bus electrode is located.

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