RU171465U1 - Reversible Switching Conductivity with Reverse Conductivity - Google Patents

Abstract

Usage: for semiconductor switches. The essence of the utility model consists in the fact that a reversibly switched dynistor with reverse conductivity is a four-layer pnpn structure with anode p- and cathode n-emitters shorted by shunts, where cylindrical nnp-diodes embedded in counter-parallel are built into the four-layer structure four-layer structure, and the p-emitter of the four-layer structure is shorted by anode shunts located around the cathode emitters of the built-in diodes. EFFECT: provision of the possibility of commutation by the dynistor of powerful alternating current pulses. 3 s.p. f-ly, 3 ill.

Description

The utility model relates to power semiconductor technology and can be used in semiconductor switches of electrical energy.

A known design of a reversible-switched dynistor (RVD) [1], which is a four-layer p ⁺ -n-p-n ⁺ structure with cathode and anode emitter pn junctions shorted by technological shunts, and the shunt of one emitter has the shape of a cylinder located coaxial with the shunt of the second emitter, in the form of a ring or an equilateral hexagon.

The disadvantage of this technical solution is a large voltage drop and, accordingly, large energy losses during the flow of reverse current. The reason for the large voltage drops is the eccentric arrangement of the cathode shunts of the dinistor (anode of the diodes), relative to the geometric axis of the anode shunts (cathode of the diodes). This arrangement of shunts leads to a significant increase in the active length of the high-resistance areas of the integrated diodes and large voltage drops on them. As a result, the maximum allowable pulsed reverse current in the HFR is several times lower than the maximum permissible pulsed forward current (≥10), which prevents the use of the HFD in the switches of powerful alternating current pulses. To use reversible-switched dynistors in these switches, it is necessary to connect additional circuit elements to the RVD, namely, an external antiparallel diode and a saturation inductor, which prevents the passage of the RVD pump current to the diode. This complicates the design of the switch and increases its cost.

The proposed technical solution is devoid of this drawback and provides the ability to switch a reversibly-switched dynistor of powerful alternating current pulses without external additional elements. This is achieved with the help of the design of a reversibly switchable dynistor with reverse conductivity (RVDD), which is a four-layer p ⁺ -n-p-n ⁺ structure with an anode p ⁺ and cathode n ⁺ emitters shorted by shunts, in addition, in a four-layer the structure has n ⁺ -n-r-p ⁺ cylindrical diodes embedded in opposite parallel to the four-layer structure, and the four-layer p ⁺ emitter is additionally shorted by anode shunts located around the cathode emitters of the built-in diodes.

An additional positive effect is achieved when the diameters of the cathodic and anodic emitters of the built-in diodes are equal and coaxial with each other, and the anodic shunts of the four-layer structure of the dynistor are at the corners of equilateral hexagons, in the center of each of which is the cathode emitter of the built-in diode, and the diameter of the anode shunts of the four-layer structure the dinistor should be less than the diameter of the cathode emitters of the built-in diodes, and the total area of the anode shunts of the dinistor should be equal ummarnoy area cathode emitters embedded diodes.

The silicon structure of the WFDD is a power integrated circuit consisting of a large number of identical unit cells (EJ), each of which contains thyristor (p ⁺ -n-p-n ⁺ ), transistor (n ⁺ -p-n ⁺ ) and diode (n ⁺ -n-p-p ⁺ ) sections.

The features that distinguish the proposed technical solution include:

- a built-in antiparallel n ⁺ -n-p-p ⁺ diode is formed in the shape of a right circular cylinder;

- the central location of the cathode of the built-in diode within the area of an equilateral hexagon, in the corners of which are the anode shunts of the four-layer structure of the dinistor;

- a smaller diameter of the anode shunts of the four-layer structure of the dinistor compared to the diameter of the cathode emitter of the built-in diode;

- approximately equal to the area of the cathode emitter of the built-in diode and a third of the area of the anode shunts located in the corners of an equilateral hexagon.

The design of the utility model is shown in the drawings.

FIG. 1 - Radial section of a unit cell of a reversibly switched dynistor with reverse conductivity.

FIG. 2 - General view of one unit cell from the anode of the dinistor.

FIG. 3 - General view of the unit cells from the cathode of the dinistor.

1 - n-base;

2 - collector pn junction;

3 - cathode n ⁺ emitter of a dinistor;

4 - anode p ⁺ emitter of a dinistor;

5 - cathode emitter of the built-in diode;

6 - anode emitter of a built-in diode;

7 - anode shunts of the p ⁺ emitter of the dinistor;

8 - metallization of the anode;

9 - metallization of the cathode;

10 - thyristor n ⁺ -p ⁺ -p-n-p ⁺ sections;

11 - transistor n ⁺ -p ⁺ -pnn ⁺ sections;

12 - diode p ⁺ -p-nn ⁺ sections.

In this design, the inclusion of the RVDD is performed by a short-term application of a voltage of reverse polarity, which leads to the flow of a reverse current pulse - the pump current of the dinistor. At this moment, a breakdown of the low-voltage n ⁺ p junction occurs and counter injection of charge carriers from collector junction 2 and anode shunts 7 into the high-resistance n-base 1 of the dynistor. As a result, a thin and uniform layer of electron-hole plasma appears in the thyristor 10 and transistor 11 sections, which, when the voltage polarity is changed, initiates the injection of minority carriers from emitter regions 3 and 4 into the base regions of the dynistor, which leads to the fast inclusion of the entire active area of the device with low values of transitional and steady-state voltage drops.

At the pumping stage, a part of the reverse current flows through the built-in diode sections 12. However, the effect of this current on the fast switching on of the dynistor is much weaker than the pump current flowing through the anode shunts 7 in section 11. Within the EI, the reverse current of the built-in diode during pumping causes switching on thyristor sections 10 in a narrow region near the side surface of the diode. In this case, at normalized pump currents, the inclusion of a dynistor occurs nonuniformly - with a time delay associated with the propagation of the on state. The main pumping in the HPPD at a control current duration of 1-3 μs passes through the anode shunts 7 in sections 11, and the subsequent switching of the current pulse of direct polarity occurs in sections 10 and 11 uniformly over the entire area of the dynistor, without delay relative to the time the pump current passes through zero.

On the other hand, the built-in RVDD diodes have significantly lower voltage drops during the flow of a power pulse of a reverse polarity current compared to quasi-diodes in sections 11 and are capable of transmitting reverse currents comparable to direct pulse currents. The separation of the RVDD into sections 11, 10 and 12, which are responsible for pumping, the flow of direct and reverse currents, makes it possible to use the RVDD in switching modes of powerful weakly damped bipolar current pulses with current durations from several units to tens of microseconds. In this mode, the reverse current power pulses following the first forward current pulse also serve as an effective pumping into the base regions of the electron-hole plasma for switching repeatedly repeated forward current pulses.

We will consider the specific implementation of the proposed solution by the example of manufacturing a reversible switchable dynistor RVDD153-50-20 for a pulsed current of 50,000 A and a maximum blocking voltage of up to 2500 V. A semiconductor structure of p ⁺ -n-p-n ⁺ type with a diameter of 2 inches was made on the basis of neutron doped silicon KOF80-60.

On the one hand, in the n-type silicon wafer, using the diffusion of boron and aluminum, a p ⁺ -p-n-structure is formed and the surfaces are oxidized. Then, using silicon oxide photolithography, sections are opened from the p ⁺ type of conductivity under the cathode n ⁺ emitter 3 of the dinistor and from the n-type conductivity under the cathode emitters 6 of built-in diodes and anode shunts of the 7 p ⁺ emitter of the dinistor, into which phosphorus pen. Then, phosphorus is accelerated with simultaneous diffusion of boron from the side of the dinistor anode, which forms the anode p ⁺ emitter 4. Moreover, in each unit cell, the cathode emitter 6 and the anode emitter 5 of the built-in diode are placed on the same axis one below the other, and the anode shunts 7 in the amount of 6 pcs placed around the circumference in the corners of the regular hexagon around the cathode emitter 6 of the built-in diode. The size of the unit cell, consisting of a built-in diode and six anode shunts 7, forming an n ⁺ -p-n ⁺ transistor is 0.92 mm. 2690 pcs are placed on a plate with a diameter of 50 mm. unit cells of a dinistor. After the final formation of the four-layer p ⁺ -n-p-n ⁺ structure, the contact surfaces of the HPHD are metallized from the side of the anode 8 and cathode 9.

Comparative tests of the proposed design and prototype showed that the ratio of pulsed forward current to reverse current in the high pressure hoses is reduced by 7 times compared to the high pressure hoses. The operability of the RVDD semiconductor structure design was tested in the block of the preionization switch of a powerful laser system. It has been established that reversibly switched reverse conductors with a blocking voltage of up to 2500 V operate reliably in bipolar power current pulses with an amplitude of up to 50 kA and a current pulse duration of up to 150 μs. At the same time, due to the exclusion from the switch of preionization of the high-voltage diode assembly and other elements of the power circuit (delay chokes, varistors), the overall dimensions and cost of the switch based on the HPHD decreases by more than 2 times.

The source of information

[1] Copyright certificate of the USSR No. 1554690. Registered 04/04/1988. "Reversible-switched dinistor."

Claims (4)

1. Reversible switch-on dynistor with reverse conductivity, which is a four-layer p ⁺ -npn ⁺ structure with anode p ⁺ and cathode n ⁺ emitters shorted by shunts, characterized in that n ⁺ -npp ⁺ cylindrical diodes are built into the four-layer structure forms connected in opposite parallel to the four-layer structure, and the p ⁺ emitter of the four-layer structure is shorted by anode shunts located around the cathode emitters of the built-in diodes. 2. Reversible-switched dynistor with reverse conductivity according to claim 1, characterized in that the diameters of the cathode and anode emitters of the built-in diodes are equal and are aligned with each other. 3. Reversible-switched dinistor with reverse conductivity according to paragraphs. 1, 2, characterized in that the anode shunts of the four-layer structure are located in the corners of equilateral hexagons, in the center of each of them is the cathode emitter of the built-in diode. 4. Reversible-switched dynistor with reverse conductivity according to paragraphs. 1-3, characterized in that the total area of the anode shunts is equal to the total area of the cathode emitters of the built-in diodes.

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