JPS5910071B2 - Semiconductor controlled rectifier - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a semiconductor controlled rectifier (
thyristor element).

In conventional techniques for preventing thyristor destruction due to overvoltage, the thyristor is typically gate-fired when overvoltage is applied between the anode and cathode of the thyristor.

This method requires a device that detects the application of overvoltage and simultaneously supplies gate current to the gate of the thyristor. Therefore, there is a drawback that the device is large and expensive. The present invention relates to a novel thyristor element that can actively utilize leakage current generated within the thyristor element due to overvoltage to turn on the thyristor to prevent it from being destroyed by heat.

Therefore, unlike the prior art, the present invention does not require a power supply device that gate-ignites the thyristor when an overvoltage is applied, and is particularly useful for downsizing and cost reduction of the thyristor DC power transmission device. The present invention will be described in detail below with reference to the drawings. 1 and 2 show a first embodiment of the present invention. 1 is a thyristor with an NPNP four-layer structure; 2 is an anode electrode; 3 is a cathode electrode; 6 is an N-type auxiliary (emitter) region provided within the PB base layer; 4 is a PB base layer on the surface of the auxiliary region 6; 5 is a leak collection electrode provided on the PB base layer so that its protrusion 5' faces closely to the auxiliary region 6; G is the auxiliary region; 6. This is a gate electrode placed opposite to 6.

The four-layer structure portion sandwiched between the anode electrode 2 and the cathode electrode 3 constitutes the main thyristor M, and the four-layer structure portion sandwiched between the anode electrode 2 and the auxiliary electrode 4 constitutes the auxiliary thyristor S. In the device having the above configuration, when a forward voltage is applied between the anode 2 and the cathode 3 without applying an ignition voltage to the gate electrode G, the N-PB junction J2 located directly below and outside the electrode 5 The generated leakage current is collected at the leakage collection electrode 5. Since the resistance between the protruding portion 5' and the auxiliary (emitter) region 6 is smaller than the resistance between the other portion of the leak collection electrode 5 and the region 6, most of the leakage current flows as shown in FIG. As shown by i1, it flows from the protrusion 5' into the auxiliary (emitter) region 6 in a concentrated manner. The leakage current 1 is the auxiliary (emitter)
It acts as a gate current for the auxiliary thyristor S including the region 6, so when the leakage current 1 exceeds a certain value, the auxiliary thyristor S turns on and the forward current 1
F1 is playing. The forward current 1F1 spreads over the entire surface of the auxiliary electrode 4 and flows into the main thyristor Mf)n emitter layer. It is clear that the forward current 1F1 acts as a gate current for the main thyristor M, so that the main thyristor M undergoes an initial turn-on over the entire peripheral area facing the auxiliary electrode 4, and finally a complete turn-on. state. As described above, the area of the leak collecting electrode 5 is increased to collect leak current in a wide area, and the leak current is caused to flow into the auxiliary (emitter) area 6 from the protrusion 5' having a relatively small area. Then, since the current density can be increased, turf-on of the auxiliary thyristor S is more likely to occur. In other words, since the auxiliary thyristor S can be reliably turned on at a leakage current value smaller than the leakage current value at which the main thyristor M starts to break over, the main thyristor M
is also definitely turned on. Furthermore, since the conduction area of the main thyristor at the initial stage of turn-on, that is, the initial turn-on area, becomes large, it is possible to prevent the main thyristor from breaking over and causing thermal damage due to local turn-on. Therefore, the present invention provides a leak collection electrode 5
The resistance between the part other than the protrusion 5' and the auxiliary electrode 4 is increased so that most of the leakage current collected in the electrode 5 flows from the protrusion 5 into the auxiliary (emitter) region 6. It is also characterized by A second embodiment that can easily achieve such effects is shown in FIGS. 3 and 4. The configuration of the second embodiment is similar to that of the second embodiment except that an additional N region 7 is provided on the lower side of the edge of the leak collection electrode 5 near the auxiliary electrode 4 and on the PB base region between the auxiliary electrode 4 and the leak collection electrode 5. This is the same as the first embodiment. The leakage current collected at the collection electrode 5 assists (
When attempting to flow into the emitter region 6, the collection electrode 5
The path from the auxiliary N region 7 to the auxiliary (emitter) region 6 has extremely high resistance because the junction between the additional region 7 and the PB base region is reverse biased. Therefore,
The leakage current collected at the collection electrode 5 is auxiliary (emitter)
The area 6 is concentrated from the portion 5/ of the electrode 5 facing the area 6.
flows into. Another feature of this second embodiment is that the forward voltage increase rate withstand capacity (the maximum value when applying the forward voltage V to prevent the thyristor from turning on due to the displacement current generated when the forward voltage increases) is the maximum value of the first embodiment. In the case of the example, Dt can also be made larger.

That is, in the first embodiment, the displacement current generated at the J2 junction under and around the leak collecting electrode 5 is concentrated from the protrusion 5/ of the collecting electrode 5 and flows into the auxiliary (emitter) region 6. However, in the second embodiment shown in FIGS. 3 and 4, the junction between the additional N region 7 and the PB base region is reverse biased and the junction capacitor Therefore, the displacement current collected on the collection electrode 5 flows into the auxiliary electrode 4 through the additional N region 7 over almost the entire surface thereof. Therefore, in the second embodiment, concentration of the displacement current to the auxiliary (emitter) region 6 does not occur, so that the auxiliary thyristor S is not turned on by the displacement current, and the forward voltage increase rate withstand capability is increased. 5 and 6 show a third embodiment in which the electrodes 4 and 5 are formed into a ring shape with the cathode electrode 3 in the center in the embodiments shown in FIGS. 3 and 4. The current collected in the leakage collecting electrode 5 flows intensively into the auxiliary (emitter) region 6 and turns on the auxiliary thyristor, thereby turning on the main thyristor. A portion 8 that extends and connects a part of the cathode electrode 3 to the surface of the PB base region is
The displacement current generated at the J2 junction on the periphery of the cathode electrode 3 is collected in the electrode 4, and flows concentratedly into the periphery of the emitter region on the lower side of the cathode electrode 3, causing malfunction and incorrect turn-on of the main thyristor. This is to prevent it from happening. As a result, the forward voltage increase rate withstand capability of the thyristor can be increased. 7 to 9 show a fourth embodiment of the present invention.

In the figures, the same or equivalent parts as in the first to third embodiments are designated by the same reference numerals. This example} Well, auxiliary electrode 4
and a leak collecting electrode 5 are provided concentrically with the central cathode electrode 3, on substantially the same circumference, facing each other about half a circumference, and the gate electrode G for turning on the thyristor is auxiliary (
This embodiment differs from the third embodiment in that it is provided between the emitter region 6 and the emitter region. The leak current collected at the leak collection electrode 5 is transferred to the auxiliary (emitter) of the electrode.
A concentrated flow flows into the auxiliary (emitter) region from the portion facing the region 6, causing the auxiliary thyristor to turn on. The forward current of the auxiliary thyristor flows from the auxiliary electrode 4 through the PB base region to the emitter, turning on the main thyristor. In this embodiment, when a gate signal is applied to the gate electrode G to turn it on, the gate current is divided into the main thyristor part and the auxiliary thyristor part, and both of them cause the main thyristor to turn on. , the initial turn-on area is significantly increased, and the fin voltage (minimum forward voltage that must be applied between the anode and cathode to turn on the thyristor) is reduced.

10 and 11 show the fifth embodiment of the present invention, and the third embodiment
In the second embodiment shown in FIG. 4, the cathode electrode 3 and the auxiliary electrode 4 are formed into a ring shape so that the leak collection electrode 5 is in the center.

Therefore, its operation etc. are the same as in the second embodiment. FIG. 12 shows an example of a circuit in which a large number of thyristors of the present invention are connected in series and in parallel.

Voltage between anode and cathode of each thyristor Vn (n=1
, 2...) become non-uniform, each thyristor is automatically turned on at an anode-cathode voltage lower than the breakover voltage. Therefore, it is possible to prevent each thyristor from being thermally destroyed due to local turn-on due to breakover. The conventional technology requires a control circuit that applies a signal to the gate G of each thyristor to forcibly turn it on when an overvoltage is applied to the thyristor. In this case, the disadvantage is that the device becomes large and the cost increases. According to this embodiment, a thyristor-applied device that does not have these drawbacks can be obtained. In the above description, the third and fifth embodiments show examples in which the gate electrode is also used as a leak collection electrode to simplify the structure, and the other embodiments show examples in which both electrodes are separate bodies. However, these are not absolute and may be substituted for each other in other ways. It will also be apparent that the conductivity type of each region can be of the opposite type. Note that the manufacturing process of the semiconductor-controlled rectifying element of the present invention is completely the same as that of the conventional one, and only the diffusion pattern needs to be changed.

[Brief explanation of drawings]

1 is a plan view of the first embodiment of the present invention, FIG. 2 is a sectional view taken along the line -' of FIG. 1, FIG. 3 is a plan view of the second embodiment of the present invention, and FIG. 5 is a plan view of the third embodiment of the present invention, FIG. 6 is a sectional view taken along line -1 of FIG. 5, and FIG. 7 is a fourth embodiment of the present invention. 8 is a sectional view taken along line 15 of FIG. 7, and FIG. 9 is a sectional view taken along line 15 of FIG. 7.
10 is a plan view of the fifth embodiment of the present invention; FIG. 11 is a sectional view taken along line X1) A7 in FIG. 10;
FIG. 12 is a wiring diagram showing an example of a circuit used in the present invention. 2... Anode electrode, 3... Cathode electrode, 4... Auxiliary electrode, 5... Leak collection electrode, 6... Auxiliary region. 7... Additional area, M... Main thyristor, S...
Auxiliary thyristor.

Claims (1)

[Claims] 1. PNPN formed to have mutually opposite conductivity types
A semiconductor controlled rectifier consisting of a four-layer element, comprising a main thyristor formed between a cathode and an anode electrode provided in an outer region of one conductivity type and an opposite conductivity type outer region, and a main thyristor provided in an opposite conductivity type middle region. an auxiliary (emitter) region of one conductivity type, an auxiliary electrode provided spanning from the auxiliary (emitter) region to a middle region of the opposite conductivity type, and a portion that closely opposes the auxiliary (emitter) region; and a leak collecting electrode provided in the middle region of opposite conductivity type, and the leak current collected at the leak collecting electrode is directed from the close opposing portion to the auxiliary (emitter) region. A semiconductor-controlled rectifier element configured to allow a concentrated flow. 2. The semiconductor-controlled rectifier device according to claim 1, characterized in that the gate electrode is arranged between the outer region of one conductivity type of the main thyristor and the auxiliary (emitter) region of one conductivity type. 3 PNPN formed to have opposite conductivity types
A semiconductor controlled rectifier consisting of a four-layer element, comprising a main thyristor formed between a cathode and an anode electrode provided in an outer region of one conductivity type and an opposite conductivity type outer region, and a main thyristor provided in an opposite conductivity type middle region. and an auxiliary (emitter) region of one conductivity type, an auxiliary electrode provided spanning from the auxiliary (emitter) region to a middle region of the opposite conductivity type, and a portion facing the auxiliary (emitter) region. , a leak collecting electrode provided in an opposite conductivity type middle region, and a leak collecting electrode and an auxiliary (emitter) region provided in the opposite conductivity type middle region between the auxiliary electrode and the leak collecting electrode. an additional region of one conductivity type formed by excluding at least a portion of the opposing portion of the electrode, and the leakage current collected at the leakage collection electrode is transmitted between the leakage collection electrode and the auxiliary (emitter) region. The auxiliary (emitter)
A semiconductor-controlled rectifying element characterized in that it is configured to flow concentratedly into a region. 4. A semiconductor-controlled rectifier device according to claim 3, characterized in that the gate electrode is arranged between the outer region of one conductivity type of the main thyristor and the auxiliary (emitter) region of one conductivity type.