JPS58198908A - Semiconductor device equipped with protecting circuit - Google Patents

Abstract

PURPOSE:To increase the degree of integration and to prevent a surface breakdown between the emitter and base of a bipolar TR by forming a Zener diode structure between the 1st conduction type emitter area and the 2nd conduction type base area of the TR. CONSTITUTION:An epitaxial growth layer 3 is formed on a semiconductor substrate 1 and an island 10 is formed of an insulating layer 4. An N<+> layer 8 as a collector C and a P layer 5 as a base B are formed in the island 10 and an N<+> layer 7 as an emitter E is formed in a base B by impurity diffusion. Further, a P<+> layer 6 is formed at part of the P layer 5 in contact with at least the bottom surface part of the N<+> layer 7. In this case, the diameter B of the P<+> layer is less than the diameter A of the N<+> layer. Therefore, an area with higher dielectric strength than an original TR is formed at the contacting part between the P<+> layer 6 and emitter layer 7, so a breakdown occurs to not the surface, but this contacting part.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor device including a bipolar transistor.

When a high voltage is applied to the base of a bipolar transistor (hereinafter referred to as a transistor) formed on a semiconductor substrate, such as a silicon substrate, a breakdown occurs between the emitter and the base. Breakdown occurs near the surface of the silicon substrate. There are many.

When breakdown occurs on the surface of Silico 746.

For example, 5i (J
, hot carriers are generated at the interface between the device and the silicon substrate, and as a result of their binding, the transistor's Ill and current-layer characteristics are reduced.

SUMMARY OF THE INVENTION The present invention corrects the above-mentioned drawbacks, and provides a semiconductor device with a retention circuit that has a high degree of integration and prevents the emitter base M table 1 i reverse 1 field breakdown of a transistor.

Hereinafter, the present invention will be explained using Examples.

FIGS. 1 and 2 i show the structure of a semiconductor device.

FIG. 3 shows a symbolic circuit diagram.

Further, FIG. 4 shows an application example of III, and FIG. 5 shows a second application example.

First, the structure of the present invention will be described. An epitaxial growth layer 3 is formed on a semiconductor J & plate 1 made of silicon, and an island 1 is formed by an insulator 4.
0 is formed.

In this island 10, there are N"1i which becomes the collector C.
18. In the P layer 5% space B, which becomes the base B, an N+ layer 7, which becomes the emitter E, is formed by impurity diffusion.

The important thing to note is that the N+ layer 7 has an E of 1
P, which is pace 8, so that it is at least in contact with the bottom part of
A part of the layer KP''116 is formed.The diameter B of the above p+ l- is formed so that B<A with respect to the diameter of the N+ layer.

According to such a configuration, P”+,16 and emitter 7
The contact portion (shown by the thick line in Figure 2) K, which has a lower breakdown voltage than the original transistor breakdown voltage, has been formed.
Therefore, breakdown does not occur at the surface, but at this contact point.If a semiconductor device configured as described above is illustrated in an electronic circuit, a Zener diode ZD is connected between the pace emitter and the emitter as shown in Figure 3. It will be done. At this time, the breakdown voltage v8 of the Zener diode is smaller than the transistor-to-base breakdown voltage Bv[1OK, which is the original voltage of the transistor. In the transistor circuit shown in FIG. 3, the Zener diode operates during reverse operation, such as when a base V-bulk voltage is supplied. This Zener diode is of a recessed type, thereby stabilizing the surface of the paste. Namely.

Normally it breaks down on the surface of the pace.

This causes the surface to become unstable due to the injection of carriers into the Sin and Ps interfaces, increasing the recombination current at the base surface and causing H□ deterioration. This makes it possible to prevent property deterioration on the surface of the paste.

In addition, 1161Vc is supplied to the collector of the transistor, and a pace current b is supplied to the base, and when the transistor operates in the forward direction, the base 11CRIb also tries to pass through the Zener diode ZDKtIL, but since the relationship B<A, the amount of current is small and there is a concern that the characteristics will deteriorate. There isn't.

Further, since the transistor and the Zener diode can be integrally formed within the semiconductor substrate, the degree of M concentration is improved.

The method for forming a single structure was as follows: First, a paste was formed, and then an acceptor impurity such as B (boron) was ion-implanted into a part of the emitter formation region to form a P+^-poor region. After that, acceptor impurities are deposited in the emitter formation region and thermally diffused (drive-in) to form the emitter 7.
and P+ layer 6 may be formed at the same time. Note that P+ layer 6
penetrates the base layer and NaI! The structure may extend to the epitaxial layer 113.

FIG. 4 shows another embodiment of the present invention, and the symbols used correspond to those in FIG. 2.

Here, instead of P+1m6, KN+ in the emitter layer 7
A + layer 11 is formed so that the breakdown region (indicated by a thick - mark in the figure) wraps around the bottom surface of the emitter layer.

In another embodiment, the donor concentration at the peripheral surface of the emitter layer (N''JI) is suppressed to form a single N layer.

A structure may be used to prevent breakdown in the surface portion.

The semiconductor mounting structure as described above is suitable for a differential amplifier circuit as shown in FIG. 4. That is, in the conventional differential amplifier circuit, the transistor QI.

When Q is supplied with a high voltage level differential power, it will break down between the emitter and pace. As a result, the current amplification factor h□ decreases. However, in the differential amplifier circuit shown in FIG. 3, the above-mentioned defects do not occur due to the operation of the Zener diodes ZL), , ZD.

Further, the present invention may be applied to a self-propelled multivibrator as shown in FIG. Self-propelled multivibrator smell [,
Since a high discharge voltage is supplied to the base of the transistor QI-Q*, breakdown is likely to occur between the base and emitter if the conventional structure is used. However, in the circuit configuration shown in FIG. 5, the above-mentioned defects do not occur due to the operation of the Zener diodes ZD, , ZD. and transistors Q, , Q, and diodes ZD, , zO,.

Furthermore, since the load resistors RL, RL, etc. can be formed on the same semiconductor, when fabricating a semiconductor integrated circuit.

The stacking layer is improved.

As described above, when the semiconductor device of the present invention is applied to an electronic circuit to which a high voltage level input signal is supplied, there is no deterioration of the semiconductor mounting, that is, a decrease in the current amplification factor h□, etc.
Stable circuit operation can be performed. Furthermore, since the degree of integration is improved, it is suitable for semiconductor integrated circuits.

[Brief explanation of the drawing]

FIG. 1 is a plan view of essential parts showing the structure of a semiconductor device that is an embodiment of the present invention. FIG. 2 is a sectional view taken along the first layer line in FIG. 1. Figure 3 is a circuit diagram symbolizing a semiconductor device. Fig. 4 is a sectional view of the main part for explaining another embodiment of the present invention, Fig. 5 is a circuit diagram showing the first application example, and Fig. #I6 is a circuit diagram showing the second application example. be. l...Semiconductor substrate, 2...Drilling layer, 3...Nl
l epitaxial layer, 6...P+ layer, 9...insulating film, 11...N++ layer, Q,,Q,...transistor, ZD,. ZD, , Zener diode, Rb1. Rb3. R
e1゜Rel...Resistance. Figure 1 Figure 2 Figure 3 Figure 5 Figure 4
Figure z

Claims (1)

[Claims] A semiconductor device t11 in which a bipolar transistor is formed on a semiconductor substrate, characterized in that a Zener diode structure is formed between the -th conductivity type Ivy region of the bipolar transistor and the 112 conductivity type paste layer. A semiconductor device equipped with a circuit.