JPS6331411Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gate turn-off thyristor (also referred to as GTO) with an amplified gate structure, particularly a GTO with a buried gate layer.

In this type of GTO, the cathode emitter is divided into two parts, an auxiliary GTO region and a main GTO region, and a buried gate layer with a high impurity concentration is formed in the P layer (base) that is connected to the cathode emitter. can be,
GTO designed to increase total tightening pressure
are shown in Figures 1 and 2.

In Fig. 1, 1 is a reinforcing tungsten plate;
2 is P layer (anode emitter), 3 is N layer, 4 is P layer, 7 is P ^- layer (cathode base), 8 is N layer,
9 and 10 are cathode emitters, and a PNPN layer is formed on the tungsten plate 1. By dividing the cathode emitters 9 and 10 into two, an auxiliary GTO region A and a main GTO region C are formed. 5 and 6 are buried gate layers (high impurity concentration layer) formed in the P layer 4, 11 is an off-gate electrode, 12 is an aluminum electrode (cathode), 13 is an on-gate electrode, 14 is an aluminum wiring, 15 is a molybdenum plate, 16 is an oxide film (SiO ₂ ). Between the buried gate layers 5 and 6 is a main GTO region C and an auxiliary GTO.
This becomes region B which separates region A. This region B is for preventing the gate current flowing from the on-gate electrode 13 of the auxiliary GTO from flowing into the main GTO through the path indicated by arrow _a1 .
Most of the gate current is for firing the auxiliary GTO. In addition, this area B has the minimum necessary width in order to increase the tightening surface.
Along with this, the aluminum electrode 12 is extended in the auxiliary GTO direction, and the buried gate layer 5 in the main GTO region C is extended in the auxiliary GTO direction to reach just below the end of the aluminum wiring 14 on the main GTO side. A stretching section 5A is provided. Note that the oxide film 16 is formed so that the extended portion (region C ₁ ) of the aluminum electrode 12 and the P ^- layer 7 are insulated.

By reducing the separation region B in this way and extending the buried gate layer 5 in the direction of the auxiliary GTO on the aluminum electrode, it becomes possible to expand the area of the molybdenum plate 15 that contacts the aluminum electrode 12, making it possible to tighten it. This allows the total pressure to be increased.

However, with the above structure, although the pressurized area can be expanded, if a part of the oxide film 16 between the aluminum electrode 12 and the cathode base 7 becomes insulated,
The cathode base 7 and aluminum electrode 12 will be shot. If the GTO is used in such a state, a voltage of several tens of V is normally applied between the cathode aluminum electrode 12 and the cathode base 7 when turning off the GTO or keeping it in the off state, resulting in a large amount of leakage current. .

Further, in the GTO having the structure shown in FIG. 2, the cathode emitter 9 is also extended in the direction of the auxiliary GTO, and the pressurizing area can be increased as in FIG. 1. However, in this case, the aluminum electrode 12 and the cathode emitter 9 are bonded over substantially the entire surface.

In the GTO with this structure, an amplified gate current flows as shown by the arrow _a2 , but some of this current flows between the cathode emitter 9 and the cathode base 7.
The current flowing through the extension of the junction (area C ₂ ) is mainly
Does not contribute to GTO ignition. Therefore, the ignition characteristic is worse than that of the GTO having the structure shown in FIG.

This invention was made to eliminate the above-mentioned drawbacks, and the cathode emitter, cathode electrode, and buried gate layer of the main GTO region are moved toward the auxiliary GTO so that the separation region has the minimum necessary width. A gate turn-off thyristor with an amplification gate structure that can increase the pressurized area while maintaining sufficient performance by extending the extension and forming an oxide film on the extended part between the cathode emitter and cathode electrode to insulate it. The purpose is to provide

Hereinafter, the present invention will be explained in detail based on illustrated embodiments.

Figure 3 shows one embodiment of the present invention.
The same parts as in the figures and FIG. 2 are given the same reference numerals. In this example, the aluminum electrode 1 of the main GTO area C is
2. The cathode emitter 9 and the buried gate layer (high concentration P-type buried layer) 5 are extended in the direction of the auxiliary GTO so that the isolation region B has the minimum necessary width, as in the case of Fig. 2. However, in this embodiment, the oxide film 16 is provided so that the aluminum electrode 12 and the cathode emitter 9 are insulated in the extended portions (regions C ₁ and C ₂ ).
is formed. The edge of the extended portion 5A provided in the buried gate layer 5 reaches directly below the end of the aluminum wiring 14 on the main GTO side.

With the above structure, the area of the aluminum electrode 12 increases, allowing the use of a wide area molybdenum plate 15, increasing the total tightening pressure, and reducing thermal resistance. Furthermore, in the regions C ₁ and C ₂ , the cathode emitters 9 are also extended, and the oxide film 16 is formed between the aluminum electrode 12 and the cathode emitters 9 , so some defects may occur in the oxide film 16 . Even if the GTO is turned off, the cathode aluminum electrode 12 and the cathode base 7 will not shoot, and the leakage current when the GTO is turned off or maintained in the off state is reduced as much as possible. Moreover, since the oxide film 16 is present in this portion, the gate current (arrow a ₂ ) amplified by the auxiliary GTO is effectively used as the ignition gate current of the main GTO.

As described above, according to the present invention, it is possible to provide a gate turn-off thyristor with an amplification gate structure that can increase the pressurized area while maintaining sufficient performance.

[Brief explanation of the drawing]

Figures 1 and 2 show the amplification gate structure, respectively.
FIG. 3 is a vertical cross-sectional view showing an example of the structure of a GTO, and FIG. 3 is a vertical cross-sectional view showing an embodiment of the present invention. 1...Tungsten plate for reinforcement, 2...P layer (anode emitter), 3...N layer, 4...P layer, 5,
5A and 6...Buried gate layer, 7...P ^- layer (cathode base), 9 and 10...Cathode emitter, 12...Cathode aluminum electrode, 13...Gate electrode, 14...Aluminum wiring, 15 ...Molybdenum plate, 16...Oxide film.

Claims (1)

[Scope of utility model registration request] The N layer, which serves as the cathode emitter of the PNPN layer, is divided into two, an auxiliary GTO region and a main GTO region,
In a gate turn-off thyristor with an amplification gate structure in which a high concentration buried layer is formed in the P layer connected to the cathode emitter, the cathode electrode of the main GTO,
Assists cathode emitter and high concentration buried layer
The isolation region between the GTO region and the main GTO region is extended in the direction of the auxiliary GTO so that it has the minimum necessary width, and an oxide film is placed between the cathode electrode and the cathode emitter in an area corresponding to the extended portion. A gate turn-off thyristor having an amplification gate structure.