JPS5940305B2 - thyristor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thyristor, and particularly to a structure for improving di/di tolerance in a thyristor having an auxiliary thyristor gate.

Turn-on in the thyristor starts in a small area near the gate by the gate signal and expands to the entire area over time.

Therefore, the effective current-carrying area immediately after turn-on is small, and the rapid increase in main current (di/dt) increases the current density near the gate immediately after turn-on, causing a rise in temperature and deterioration of device characteristics and damage. is generally known. As one means for increasing the di/dt tolerance, there is a thyristor equipped with an auxiliary thyristor.

The structure of this example is shown in FIG. 1 as a top view, and as shown in FIG. 2 as a cross-sectional view taken along line A'A' in FIG. From P, , Ni, P2
are formed by laminating each region, and the P, (anode)
A region P is connected to the anode electrode A, a (gate) region is partially exposed on the main surface opposite to the main surface of the element, and a ring-shaped cathode region of the main thyristor section is connected to the main surface (opposite). An N2 region is formed. Furthermore, on the inner side thereof, there is an auxiliary thyristor gate N3 region formed in a concentric ring shape. Further, P-type high concentration layers p and f are formed in the surface layer of the P region. 2 and 3 in the figure are shorted emitters, which are provided throughout the cathode region N2 of the main thyristor.
In the figure, description of the entire area is omitted and only a part is shown), and 3 (only a part is shown as in the above) provided in the entire area of the auxiliary thyristor gate N2 region. In each figure, G represents a gate electrode, KS represents an auxiliary thyristor electrode, and KS represents a cathode electrode.

With the above structure, upon application of the gate current, the gate current flows through the emitter of the auxiliary thyristor to the emitter of the main thyristor, causing the auxiliary thyristor to fire first. This ignition instantaneously creates a strong electric field between the auxiliary thyristor and the main thyristor, causing rapid turn-on from the main emitter inward, expanding the initial ignition region and increasing V) di/d. In the center gate auxiliary thyristor shown in FIG. 1, its periphery is surrounded by emitters}B. dv/d1
The generated current flows out through the short circuit provided in the emitter. However, D inside the gate and auxiliary thyristor
The current generated by V/Dt, etc. flows through the P base and through the short circuit near the gate, but the area of this part is relatively large and the generated current is large, and since this part is the initial lighting area by the gate signal, it is There is a tendency for erroneous lighting due to the rise in temperature, Dv/Dt, etc. This also has the disadvantage that the turn-off characteristics deteriorate. To prevent this, there are methods to short-circuit the N layer of the emitter to the auxiliary thyristor by setting an appropriate impedance, and to short-circuit the cathode electrode inside the emitter, but none of these methods are sufficient, and improvements are strongly desired. Ta. The present invention has been made in response to the desire for improvements to the conventional thyristors described above, and its object is to provide a thyristor structure with excellent turn-off characteristics.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings, illustrating one embodiment of a thyristor having an auxiliary thyristor.

3 is a top view, FIG. 4 is a sectional view taken along line B'B' in FIG. 3, and FIG. 5 is a sectional view taken along line CC' in FIG. 3. , A is an anode electrode disposed in the first P region layer P1;
A first N region layer N facing the region layer Pl, a second P region layer P facing the first N region layer N1 and forming a gate; gate electrode G
, a second N region layer N, , formed by selective diffusion on a part of the exposed surface of the second P region layer Pl2, a thyristor main electrode K disposed on the region layer, and a thyristor main electrode K disposed on the region layer; P area layer P1
A third N-region layer N, 3 formed by diffusion along the periphery of the second N-region layer N]2 forms an auxiliary thyristor region, and a second 10P-region layer P1 is formed from a part of this region layer. ! , a high concentration P region layer P on the exposed surface layer, an auxiliary thyristor electrode K8 formed extending over a part of the soil, the second N region layer N, .
from the opposite edge facing the third N region layer N,3 to this second
The protruding region layer P of the second P region layer protruding into the N region layer of
1 and a short-circuit part P, with the cathode electrode provided on the surface layer; 2. The cathode region layer N, . Penetration portion P of second P region layer P,
It has a so-called emitter short-circuit structure, which has a plurality of t and V).

According to this invention, the protruding region layer P1 of the second P region protruding to the emitter layer and the cathode electrode are arranged along this and short-circuited at P22', and the low impedance of the surface causes V)Dv The current generated by /d1 flows into the cathode electrode at P2,'' through the P2,+ layer.

Regarding Di/Dt, a strong electric field is generated between the auxiliary thyristor and the main thyristor, and the firing current from the auxiliary thyristor is divided into two routes: one route flows through the P22 layer and flows into P22'', and the other route flows under the base layer. In other words, the electrode K of the auxiliary thyristor
The P, 2 layer exhibits this effect without depending on S, and can lengthen the peripheral length of the emitter, showing a remarkable effect on the initial ignition characteristic.

[Brief explanation of drawings]

1 and 2 show a conventional center gate thyristor. FIG. 1 is a top view, FIG. 2 is a sectional view taken along line NN in FIG. The center gate thyristor of the example is shown.
The figure is a cross-sectional view along line B in Figure 3, and Figure 5 is a cross-sectional view along line C in Figure 3.
FIG. 2 is a cross-sectional view taken along line /C'. The same reference numerals in the obituaries indicate the same or corresponding parts, respectively. P,...first P region layer, A...anode electrode, N,...first N region layer, Pl2...second P (gate) region layer, N,...・Second N (emitter) region 5 layers, P22'... protruding region layer of second P region layer, P,2... short circuit between P22 region layer and cathode electrode, G... gate Electrode, K...Cathode electrode, K,
... Auxiliary thyristor electrode, N, 3... Third N region (auxiliary thyristor) layer.

Claims (1)

[Claims] 1 a first P region layer of an anode, a first N region layer facing the first P region layer, a second P region layer facing the first N region layer forming a gate, and a second P region layer facing the first N region layer forming a gate; The second cathode formed by selectively diffusing a part of the exposed surface of the P region layer No. 2
a third N-region layer that is diffused into the second P-region layer along the periphery of the second N-region layer to form an auxiliary thyristor region; a protruding region layer of the second P region layer that protrudes into this region layer from an edge opposite to the third N region layer; a cathode electrode formed on the second N region layer; and a cathode electrode formed on the second N region layer; A short-circuit portion with the cathode electrode formed by shorting the protruding region layer of the P region layer with the cathode electrode at its protruding end, an anode electrode disposed on the first P region layer, and a second P region layer. A thyristor comprising a gate electrode disposed in the thyristor.