JPS63224361A - Buried gate gto thyristor - Google Patents

Abstract

PURPOSE:To improve the current efficiency of an ON gate current and to reduce the capacities of a gate power source and a gate current control element by forming an insulating film on an emitter layer at a part opposed to a gate layer. CONSTITUTION:An insulating film I2 made of SiO2 is formed on an emitter layer N2 region opposed to a buried gate P2<+> formed on a high concentration impurity layer P. This film I2 utilizes a mask pattern used to form a base layer P2<+> in the same width as that of the buried layer P2<+> to form simultaneously upon the formation of an insulating film I1. Accordingly, a gate current from a buried layer P2 scarcely feed to a region ohmically contacted with a cathode electrode K of an emitter layer N2 to easily inject electrons from the emitter layer N2 in an effective thyristor section for turning ON, thereby increasing the utility efficiency of a gate current and reducing the gate current. Thus, the capacities of a gate power source and a gate current control element can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a GTO (gate turn-off) thyristor with a buried gate layer.

80 Summary of the Invention The present invention improves on-gate current efficiency by forming an insulating film between the surface of the emitter layer and the emitter electrode in a portion facing the buried gate layer in a buried gate type GTO+iristor. It was designed so that it could be made higher.

C0 Prior Art A GTO thyristor with a buried gate layer is constructed as shown in FIG. PI @ Nl m Pl e N1
A lattice-like or strip-like impurity layer P- with a height of 1 mg is embedded in the Pt base layer, and an ohmic connection is obtained with the gate electrode G using this Pt layer as a gate layer. P! ″
'' is a low concentration impurity layer, A is an anode electrode, K is a cathode electrode, and 1 is an insulating film.

Compared to the cathode split type GTO thyristor shown in Fig. 3, the Gτ0 thyristor with such a structure can easily insulate the gate and cathode, has excellent area utilization efficiency and thermal resistance characteristics, and is suitable for GTO thyristors for high power control. It is widely used in Irista.

D0 Problems to be Solved by the Invention In the conventional buried gate type GTO thyristor, the utilization efficiency of the turn-on gate current is higher than that of the cathode split type GTO thyristor.
There was a problem that it was inferior to thyristors. This will be explained in detail below.

In the architecture of FIG. 2, the on-gate flow consists of a connected buried gate layer P1 and a single L-mitter layer N.

It flows as shown by the arrow. At this time, the effective thyristor part that turns on becomes the projection region q where the buried gate layer P1+ does not exist, and in this projection region S, N,
Only the gate current flowing into the emitter layer becomes effective as an on-state current.

That is, among the distributed gate current components, electrons are injected from the emitter layer due to the gate current component flowing into the N region, but these are trapped in the heavily doped buried layer p, and are injected from the base layer. It becomes an ineffective ingredient that does not excite. In contrast, the purchase shown in FIG. 3 does not have the above-mentioned ineffective components.

Therefore, in a buried gate type GTO thyristor, the gate turn-on current is larger than that in a split cand type GTO thyristor, and the turn-on gate current is used less efficiently, and a large capacity gate power supply and gate current control board must be prepared. Must be.

1. Means and operation for solving the problem The present invention was made in view of the above points, and has four layers of PNPN, and a highly concentrated impurity layer is entirely formed in the base region. In a buried gate type GTO thyristor with /il as the gate layer, the emitter is formed in the part facing the gate layer)
Is there an insulating film between the emitter electrode and the surface? This structure allows the flow from the buried gate 1@ to easily flow to the effective iris register section.

F, real tIIfA example FIG. 1 shows an example of an element vR showing an embodiment of the present invention.

The difference between this figure and Figure 2 is that P becomes a high-opening impurity layer.
1 + Insulation work such as 8101 on the N opposite to the buried gate, emitter layer area table diagram! It is at the point where it was formed. When the insulating film 8 is made to have the same width as the P base layer, it is formed simultaneously with the formation of the insulating film 1 using the mask pattern used for forming the P base layer.

According to the above structure, the gate current from the Pt layer easily flows to the region of the N emitter layer that makes ohmic contact with the cando electrode (the region where the insulating film is not formed). Therefore, it becomes easier to inject electrons from the N layer in the effective iris resistor section for turn-on, thereby increasing the gate current utilization efficiency and reducing the gate current.

As an example based on this example, we made prototypes with the structure shown in Figure 2 and the structure shown in Figure 1 under the same conditions for each part, and measured the minimum on-state current. We were able to reduce the number to about 115.

In addition, in the example, the case where the size is the same as that of the insulating film 1st "Pt" shield is shown, but this does not necessarily have to be the same, and as long as the two face each other, the on-gate current efficiency will be improved. It has the effect of increasing

G1 Effects of the Invention As described above, the present invention has a structure in which an insulating film is formed on the surface of the emitter layer in the part facing the gate layer, so that the on-gate current of the buried gate layer easily flows to the effective thyristor part, and the on-gate current Improve the current efficiency of the gate.
-4 sources and gate current control elements can be made smaller.

[Brief explanation of drawings]

FIG. 1 is a curved view showing an embodiment of the present invention, FIG. 2 is a sectional view of a conventional buried gate type GTO thyristor, and FIG. 3 is a sectional view of a canned split type GTO thyristor. P? ...buried gate layer, ...insulating film.

Claims (1)

[Claims] A buried gate type GTO that has four layers of PNPN and has a high concentration impurity layer formed in its base region and uses this layer as a gate layer.
A buried gate type GTO thyristor characterized in that an insulating film is formed on a surface of an emitter layer at a portion facing the gate layer and between the emitter electrode and the emitter electrode.