JPS6043036B2 - thyristor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The invention relates to a semiconductor comprising an N emitter layer with an outer first electrode, a P emitter layer with an outer second electrode and a base layer adjacent to each of these layers. a substrate, and an emitter disposed on the surface of this semiconductor substrate, capable of switching off the conduction of the thyristor by selectively bridging the PN junction between one of the two emitter layers and an adjacent base layer to a low resistance. Concerning a thyristor with a short circuit.

Such a thyristor is known from US Pat. No. 3,243,669.

In that, a controllable emitter short is formed between a semiconductor region of a first conductivity type connected to the cathode (anode), a second semiconductor region of the first conductivity type connected to the base layer, and between these regions. an intermediate layer of a second conductivity type present in the thyristor, in which case the intermediate layer is covered by a gate with a control terminal located at the interface of the thyristor and separated from it by a thin electrically insulating layer. . When the emitter short is turned off by applying a control voltage to the control terminal, the thyristor is converted from an on state to an off state in which no load current can actually flow, regardless of the voltage applied in the forward direction.

The transition from the OFF state to the ON state is controlled via an insulated gate PN between both base layers inside the thyristor.
This is done by applying a second control voltage to the gate of another shorting structure bridging the junction. The short-circuit structure naturally requires relatively high connection costs. Another difficulty is that the two control voltages must be synchronized one after the other in time. The object of the invention is to provide a thyristor of the first-mentioned type which has a simple construction and can be operated in a simple manner.

The purpose of this is to divide the N emitter layer (P emitter layer) into a plurality of strip-shaped emitter regions, each of which is conductively interconnected to each other to form a first (second) electrode.
In addition, a plurality of strip-shaped short-circuit electrodes are electrically conductively connected to each other.
A shorting electrode provided along the emitter region and in contact with a portion of an adjacent base layer extending to the surface of the semiconductor substrate inside each emitter region and further in contact with the base layer is connected to the first (first) 2) a firing electrode wire-connected to each part of the electrode via a controllable field effect transistor, the base layer or one area thereof having a terminal for a firing circuit, said controllable field effect transistor; is achieved by having a control input connected to the ignition circuit.

The advantage obtained by the invention lies in particular in that the turning-off of the thyristor from the on state to the off state and vice versa takes place in each case by the same short-circuit structure provided on the surface of the thyristor.

The present invention will be explained in detail below with reference to the drawings. The thyristor shown in FIGS. 1 and 2 consists of semiconductor layers 1 of alternating conductivity types made of, for example, bottom-pumped silicon.
It has a semiconductor element having 1 to 4. In it the emitter area 1a. The outer N-type layer 1 consisting of 1d to 1d is called the N-emitter layer, and the outer P-type layer 4 is called the P-emitter layer. P-type layer 2 and N-type layer 3 form a so-called base layer. The P emitter layer 4 is provided with an anode 5 having an anode terminal A. The emitter zones 1a to 1d can be seen in FIG. This annular structure forms the outer part of the short-circuiting electrode, which is completed in FIG. 2 by connecting passages 7 to 9 passing above and below.
These connecting paths each form a short-circuit electrode that runs alongside the strip-shaped N emitter sections 1a to 1d. For clarity, portions 6 to 9 are shown with diagonal lines in FIG. From FIG. 1, which shows the sectional view taken along the line I-1 in FIG. It's covered.

Short-circuiting electrodes 7 to 9 are each provided on each part of the base layer 2 extending up to the surface F. The parts 7 to 9 which are conductively connected to each other and to the part 6 are led to a first terminal of an electronic switch, for example a field effect transistor 14, and a second terminal of the electronic switch. The children are connected to a common cathode terminal K. When a control voltage U1 is applied to the control terminal G of the electronic switch 14, the electronic switch 14 closes, the PN junctions between the emitter regions 1a to 1d and the base layer 2 being respectively short-circuited via the switch 14. As a result, the thyristor is in an off state in which no load current actually flows through the terminals A and K, regardless of the voltage of forward polarity.The thermally generated holes are guided from the base layer 2 towards the cathode. , N emitter areas 1a to 1d do not inject carriers into the base layer 2.If the shorting electrodes 7 to 9 inside the ring 6 are uniformly distributed, a good protection of the thyristor against undesired ignition phenomena is achieved. Stability occurs. When the control voltage U1 of G is turned off just as the time t1 is reached, the switch 14 opens and the emitter short-circuit is thereby ineffective. As a result, the thyristor fires. The load current changes accordingly. flows through a low-resistance thyristor in the load circuit connected to A and K. The thyristor is turned off at that moment by applying GICU1 again. An alternating voltage is present across A and K. If the zero potential passage occurs before the application of U1,
Turn-off also takes place thereby. According to the development of the present invention, if the switch 14 is provided with a DC power supply 15 in series with the polarity such that when the switch 14 is closed, a voltage is applied in the opposite direction to the PN junction between 1a to 1d and 2, the turn-off operation can be performed. is promoted, resulting in better blocking properties in the off-state.

In order to accelerate the ignition process, it is further advantageous to modify the circuit shown in FIG. 1 in such a way that the shorting electrode, e.g. .

The separated electrodes are then connected to terminal Z of the ignition current circuit Z1. Electrode 8 thereby acts as an ignition electrode.
Optionally, electrode 8 can also remain connected to parts 6, 7 and 9, in which case these parts also serve as ignition electrodes. The ignition pulse P1 provided by Z1 is immediately applied to the base layer 2. FIG. 3 shows another embodiment of the invention.

It differs from FIG. 1 in that parts 10 to 13 are no longer connected to the cathode terminal K and form parts of an auxiliary emitter electrode. There is no outer ring 6, in this case part 1
The left edge of 0 is extended beyond the left edge of the N emitter area 1a to bridge the PN junction between 1a and 2 located there. The same is true for the right edge of 13 bridging the PN junction at the right edge of 1d. Further in FIG. 3, main emitter layers 16 and 17 are provided, which are covered by cathode parts 18, 19. Portions 18, 19 are led to a common cathode terminal K. The main emitter layers 16 and 17 are formed on the surface F of the base layer 2.
It is penetrated by a region which extends up to and is connected here with parts 18, 19. Area 20 forms a fixed emitter short which prevents undesired firing action in the main emitter layer in the off-state of the thyristor. electronic switch 14
It is effective to form the terminal G so that it is in a closed state unless a control voltage is applied to the terminal G. When the switch 14 is closed, the Pn junction between the base layer 2 and the auxiliary emitter regions 1a to 1d is bridged to a low resistance, so that no auxiliary current is formed in the region of the auxiliary emitter regions.

Upon application of voltage pulse P1 to gate G, switch 14
opens, the bridge is removed and an auxiliary emitter current is created which is directed through the extended edge areas of parts 10 and 13 into the main emitter regions 18 and 19 and causes a rapid ignition action there. The thyristor is thereby switched into a conductive state with a load current flowing between A and K. Even when the switch 14 closes again after falling P1 and the auxiliary emitter current is interrupted, the main current flowing through the N main emitter layer continues.
Only then, when the voltage between the anode and cathode is interrupted or, if an alternating voltage is used, by the next passing of that voltage to zero potential, is the thyristor switched into the off state. The improvement in stability due to the connection of the power supply 15 which applies a reverse voltage to the Pn junction between the areas 1a to 1d and the layer 2 treated with reference to FIG. 1 also applies to the embodiment shown in FIG. It's meaningful.

Furthermore, here too, the ignition operation can be facilitated by the connection of the ignition current circuit Z1 already mentioned.

G can then be connected to terminal Z of the ignition current circuit Z1. In this case, a pulse voltage is used as a pulse P1 which can be taken out at Z when supplying the ignition current to the base layer 2. Thyristors with auxiliary emitter sections are described in the book, Semiconductor Electronics Series Volume 5, Spenke (
E. Spenk) “Pn junction (Pn-Ubergan)”
ge)” Berlin, Springer Verlag (Spring?)
RVerlag) 197 Kui Publishing, No. 123 and 124
It is written on the page.

The switch 14 advantageously consists of an MIS field effect transistor, which can advantageously be integrated into the semiconductor body of the thyristor.

Apart from the embodiment of the present invention described above, an emitter short section that can be turned off may be attached to the P emitter layer 4.

For the explanation of such a thyristor structure, FIGS. 1 and 3 may be used with the symbols A and K interchanged, with the entire semiconductor section having an opposite conductivity type, and the voltage or pulsed voltage used. It helps if you reverse the polarity.

[Brief explanation of the drawing]

FIG. 1 is a sectional view taken along line I-1 in FIG. 2 of an embodiment of the present invention;
FIG. 2 is a plan view thereof, and FIG. 3 is a sectional view of another embodiment. 1a, 1b, 1c, 1d...emitter area, 2
...p base layer, 3...n base layer, 6,7
, 8, 9... Short circuit electrode, 10, 11, 12, 1
3... Emitter electrode, 14... Field effect transistor, 16, 17... Main emitter layer, F... Semiconductor substrate surface, 21... ...Ignition circuit.

Claims (1)

[Claims] 1. A semiconductor substrate comprising an N emitter layer with a first electrode on the outside, a P emitter layer with a second electrode on the outside, and a base layer adjacent to each of these layers; in which the N
The emitter layer (P emitter layer) is divided into a plurality of striped emitter regions, and each of the divided portions is conductively wired to each other to form a first (second) electrode, and is also conductively connected to each other. A plurality of strip-shaped shorting electrodes are provided along the emitter region and contact portions of an adjacent base layer that extend to the surface of the semiconductor substrate inside each emitter region, and further contact the base layer. A short-circuiting electrode is wire-connected to each part of said first (second) electrode via a controllable field effect transistor, and the base layer or one area thereof has a ignition electrode with a terminal for an ignition circuit. Thyristor, characterized in that the controllable field effect transistor has a control input terminal connected to the ignition circuit.