JPS5936918Y2 - thyristor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thyristor structure that allows the gate firing current to be adjusted as required without changing the gate firing voltage.

Conventionally, in a thyristor having an amplification gate structure, for example, as shown in FIG. 1 and FIG. A current flows through the cathode 3, and at that time, a potential difference is generated due to the equivalent resistances R1 and R2 of the P base layer, and the potential difference of the lower resistance R1 of the auxiliary emitter region 4 increases between the P base layer 8 and the auxiliary emitter region 4. When the minority carrier injection potential becomes larger than , electron injection occurs from the auxiliary emitter region 4 to the PN base layer 8, and the anode
．． Depending on the voltage applied between the cathode 3 and the
Equivalent resistance R of emitter layer 10, N base layer 9, P base layer 8, auxiliary emitter region 4, auxiliary electrode 7, P base layer 8
2. A current flows through the short-circuit portion 2, and the potential difference generated across the equivalent resistance R2 increases, so that the main emitter region 1 becomes conductive, and the anode 11 and cathode 3 become completely conductive.

On the other hand, when a negative voltage is suddenly applied to the cathode 3 and a positive voltage to the anode 11 due to the junction capacitance C existing in the junction J2, a displacement current (2) of the following equation is generated.

dv -・・・・・・・・・
...(1)■-Cd1 This displacement current ■ acts equivalently like a gate current, and there is a risk that the thyristor will be turned on unnecessarily, especially in the main emitter region around the thyristor. In 1,
The current density of the displacement current I increases, and the probability of transitioning to a conductive state at an unnecessary time increases.

Therefore, the peripheral part of the main emitter region 1 is short-circuited with the P base layer 8 by the metal of the cathode 3, and a method is adopted in which the displacement current is absorbed at this short-circuited part.

However, if the periphery of the main emitter region 1 on the side where the gate 5 is located is short-circuited, it becomes impossible to transition the main emitter region 1 to a conductive state with the gate current, and the main emitter region 1
and P base layer 8 are not short-circuited around the gate 1-5 side.

Therefore, the displacement current in the part of the P base layer 8 where the main emitter region 1 is not transferred to the auxiliary emitter region 4 or the main emitter region 1.
In order to prevent the thyristor from unnecessarily transitioning to the conductive state due to the current flowing toward the P base layer 8, a ring portion 6 having the same potential as the cathode 3 is provided on the P base layer 8 to absorb the displacement current.

This ring part 6 has an equivalent resistance R3 in the P base layer 8 with respect to the gate current, and the gate current that does not contribute to the ignition of the thyristor flows through the equivalent resistance R3, so that the thyristor is ignited. This has the disadvantage of unnecessarily increasing the gate current required for this purpose.

The present invention aims to improve the drawbacks of the prior art described above, and to provide a thyristor that does not unnecessarily increase the gate current required for ignition of the thyristor and can prevent erroneous ignition due to displacement current. .

Hereinafter, the present invention will be explained in detail using an embodiment shown in FIGS. 3 and 4.

The feature of the present invention is that, compared to the prior art thyristors shown in FIGS. It is characterized in that it has a barrier layer 12 in which an impurity having the same conductivity type as the emitter region is diffused in a band shape, and that the ring portion 6 in FIG. 1 is eliminated.

The effects of the present invention will be explained below.

First, when the gate current flows from the gate 5 through the auxiliary emitter region 4 toward the cathode 3, it passes through the equivalent resistances of R1 and R2, and this gate current contributes to ignition. Although there is a gate current component that does not contribute to ignition flowing through the equivalent resistance R4 of the P base layer 8 under the barrier layer 12 and the equivalent resistance R5 of the peripheral part of the P base layer 8 without the barrier layer 12, there is a gate current component that does not contribute to ignition. 12, the equivalent resistance R4 can be made large, and the gate current component that does not contribute to ignition can be significantly reduced.

On the other hand, with respect to the above-mentioned displacement current, the displacement current generated in the peripheral part of the P base layer 8 is generated in the auxiliary emitter region 4 because the equivalent resistance R4 of the P base layer 8 under the barrier part 12 is large.
Since it does not flow in the direction of , but flows into the cathode 3 through the equivalent resistance R5, the probability of shifting to an unnecessary conduction state is reduced.

At this time, if the shorting protrusion 13 is provided on the cathode 3, the effect will be further ensured.

The following modification of the present invention is shown in FIG.

In FIG. 5, as a substitute for the barrier layer 12 in FIG.
It has a band-shaped groove 14 formed by photo-etching or the like, and it is clear that the effect is the same as that of the barrier layer 12 explained using FIGS. 3 and 4.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a thyristor according to the prior art, FIG. 2 is a sectional view taken along line A-A in FIG. 1, FIG. 3 is a plan view of a thyristor according to the present invention, and FIG. 5 is a sectional view taken along the line -B, and FIG. 5 is a sectional view showing a modified example of the cyrisk according to the present invention. 1...Main emitter region, 5...Gate, 8...P base layer, 12...Auxiliary emitter region.

Claims (1)

[Scope of utility model registration request] In a thyristor having an amplification gate 1 structure having an auxiliary emitter between the gate and the main emitter, an impurity region having the same conductivity type as the auxiliary emitter is formed in a band shape on the side opposite to the auxiliary emitter with respect to the gate position. Cyrisk is characterized by: