JPS6126232B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor electronic switch circuit element that uses a thyristor and is less likely to malfunction.

To prevent dv/dt effects (or rate effects) in the thyristor, its gate (G), cathode (K)
Inserting a resistor between them is called a short emitter and is already known, but in this method, the dv/dt
It is known that reducing the resistance between the gate and the cathode in an attempt to improve the withstand capability lowers the gate sensitivity and increases the holding current, which is a problem in semiconductor electronic switch circuits including thyristors. Therefore, a circuit as shown in FIG. 1 has been devised.

In FIG. 1, a thyristor 1 has a P emitter layer P _E and an n base layer N, whose adjacent layers have different conductivity types.
It is composed of four layers: _B , P base layer P _B , and n emitter layer n _E , and there is a resistance of 10 to 15 KΩ between the gate provided on the P base layer P _B on the cathode side and the cathode provided on the n emitter layer n _E. High resistance 2 and n collector layer n _C ,
A transistor 3 consisting of three layers, a P base layer P _B and an N emitter layer n _E, is connected, and a capacitive element 4 such as a capacitor is provided between the base of the transistor 3 and the anode of the thyristor 1, and the base of the transistor 3, Diode 5 in the opposite direction between the emitters
is provided.

When a forward voltage is rapidly applied to the anode A of thyristor 1 (dv/dt), the central Pn of thyristor 1
When the junction J ₂ is charged and this charging current passes through the third Pn junction J ₃ , the thyristor 1 is turned on (it is a rate effect). However, due to the presence of resistor 2, this charging current is bypassed, resulting in a large charging current.
The voltage across resistor 2 is Pn junction J ₃ of thyristor 1
The thyristor 1 does not turn on until it reaches the forward bias rising voltage of .

Furthermore, when the rise of the forward voltage (dv/dt) increases, the charging current in the capacitor 4 flows to the base of the transistor 3, driving the transistor 3 to the on state and lowering the impedance of the transistor 3 to its saturation resistance. When a high rising (dv/dt) voltage is applied to the anode terminal, the apparent resistance between the gate and cathode of thyristor 1 decreases, so the thyristor remains off, but the resistance of transistor 3 in the on state decreases. If the thyristor is large, the resistance between the gate and cathode of the thyristor increases, resulting in high dv/dt.
Unable to tolerate.

In normal integrated circuit technology, the silicon material of the thyristor 1 and the transistor 3 are the same and are insulated from each other, and in order to make the thyristor 1 with a high withstand voltage, the resistivity of the silicon material must be high. , Therefore, the saturation resistance of the transistor 3 increases and the dv/dt tolerance decreases. In order to compensate for such drawbacks, in conventional integrated circuits, a method can be considered in which a low resistance region is partially created as necessary (for example, using epitaxy, etc.) and the transistor 3 is formed in the low resistance region. The process is complicated and the cost is high, which is industrially disadvantageous.

The present invention aims to eliminate such drawbacks and provide a semiconductor electronic switch circuit element with high dv/dt resistance by a simpler method of reducing the saturation resistance of the transistor 3.

FIG. 2 shows an example of a semiconductor electronic switch circuit element according to the present invention.

In the figure, components other than thyristor 1 and transistor 3 are indicated by symbols, but they are actually integrated. Further, although a dielectric isolation method using a silicon oxide film is used for isolation between a plurality of single crystal silicon island regions in an insulating isolation substrate, other known isolation techniques may be used.

Generally, integrated circuit devices have a large number of devices arranged on the same plane, each requiring unique characteristics, so the device structures and manufacturing processes often differ. Even in the device of the present invention, the thyristor 1 and the transistor 3 are required to have independent characteristics. The thyristor 1 is required to have a high blocking voltage, and the transistor 3 is required to have a large current amplification factor and a low saturation resistance in the on state.

Therefore, in the device of the present invention, a single crystal silicon island region having the same resistivity as a high voltage thyristor is used, and the thickness of the P base layer of the transistor 3 is reduced in order to achieve a high current amplification factor and a low saturation resistance in the on state. It is made thinner than the thickness of the P base layer on the cathode side of the thyristor 1.

Figure 3 shows the ratio of the thickness of the P base layer of transistor 3 to the thickness of the P base layer of thyristor 1 and dv/
The relationship between dt tolerance is shown.

From this relationship, in order to improve the dv/dt withstand capability, the thickness of the P base layer P _B of the transistor 3 should be
It was found that the thickness should be 70% or less of the thickness of the P base layer P _B of the thyristor 1.

In FIG. 3, the thickness of the P base layer of transistor 3 was adjusted to be thinner than that of thyristor 1 by thinning the impurity diffusion when forming the P base layer.
The same results were obtained using a method in which the impurity diffusion for forming the n-emitter layer was made deeper than the thyristor 1.

[Brief explanation of the drawing]

Fig. 1 is a connection diagram of a semiconductor electronic switch circuit element for obtaining high dv/dt withstand capability, Fig. 2 is a partial longitudinal sectional view of a semiconductor electronic switch circuit element in which the circuit shown in Fig. 1 is integrated into a semiconductor, Figure 3 shows the ratio of the P _B layer thickness of the transistor and the P _B layer thickness of the thyristor.
FIG. 3 is a characteristic diagram showing the relationship between dv/dt tolerance. 1...Thyristor, 2...Resistor, 3...Transistor, 4...Capacitor, 5...Diode.

Claims (1)

[Claims] 1. a thyristor, a high resistance and a transistor each provided in parallel between the gate and cathode of the thyristor, a capacitive element that transmits a steep voltage applied to the anode of the thyristor to the base of the transistor, and the base of the transistor;
A diode placed in the opposite direction between the emitters is
The thyristor and the transistor are formed in the single crystal silicon island region having the same resistivity, and the thickness of the base layer of the transistor is the same as that of the thyristor. 70% of the base layer thickness on the cathode side
A semiconductor electronic switch circuit element which is: