JPS62155563A - Semiconductor device - Google Patents

Abstract

PURPOSE:To provide a semiconductor device capable of withstanding a high voltage against the reverse bias voltage by making the vicinities of corners of the PN junction portion of the base with the emitter high-concentration portions which have a higher impurity on concentration than the other base portions. CONSTITUTION:A P-type impurity is first ion-implanted into an N-type collector 2C to form a base 2B, and then a P<+> type impurity of a higher concentration is ion-implanted again into the vicinities of the corner portions of the PN junction between the collector 2C and the base 2B, forming high-concentration portions 2Ba. Thereafter drive-in thermal diffusion is performed, forming and completing the base 2B. Then, an N<++> type impurity is thermally diffused into the base 2B, forming an emitter 2E. The high-concentration portions 2Ba may also be formed by the thermal diffusion method, if necessary, without being limited to the ion implantation method. The layer resistance rhos of the high- concentration portions 2Ba of a transistor 2 formed in this way is 90-110OMEGA/square, and this value is about 1/3 of the specific resistance rhos of the base 1B of an prior equivalent item, which is 300-350OMEGA/square.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor device such as a switching power transistor.

For example, in the deflection circuit of a cathode ray tube of a television receiver, an n-p-n junction transistor is used as a switching element for turning a sawtooth wave current ON and OFF. The structure of such an n-p-n junction transistor is as shown in FIG. 3, and this transistor 1 has an n-type emitter IE and a p-type base IB1.
N-type flutter ICs are formed by n-p-n junctions, and the withstand voltage value of the reverse bias voltage between the emitter IE and the base IB is usually about 300 to 350V.

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When such a transistor 1 is used as a switching element as described above, a high reverse bias voltage is often applied between the emitter IE and the base IB. has a low breakdown voltage value with respect to a reverse bias voltage, so there is a problem that the insulation between the emitter IE and the base IB is easily destroyed by a high reverse bias voltage.

The present invention has been made in view of these conventional problems, and it is an object of the present invention to provide a semiconductor device having a high breakdown voltage value against reverse bias voltage.

.゛ In order to achieve the above object, the present invention provides n-p-
A semiconductor device having an n-transistor structure is characterized in that at least the vicinity of the corner of the pn junction between the base and the emitter is made into a high-la-concentration layer with a higher concentration of impurity ions than the rest of the base.

In the semiconductor device with the above configuration, the impurity ion concentration near the junction of the base with the emitter is higher than the impurity ion seismic intensity of other parts of the base, so the high ion concentration part The layer resistance ρS becomes smaller, the impedance between the emitter and the base becomes smaller, and even if a high reverse bias voltage is applied between the emitter and the base, the insulation between the emitter and the base is not destroyed. This is thought to be because the impedance between the emitter and base is reduced, which results in less power being applied during reverse bias, and less heat generation.

Figure 1 shows an embodiment of the semiconductor device of the present invention.
The structure of n-type power transistor 2 is shown. The transistor 2 of this embodiment has n
First, a p-type impurity is ion-implanted into the collector 2C of the mold to form the base 2B, and then a higher concentration p+-type impurity is again implanted near the corner of the pn junction (collector junction) between the collector 2C and the base 2B. After ion implantation, the high concentration area 2Ba
form. After that, indentation heat diffusion is performed and the base 2
Complete formation of B. Then, the n-type impurity is added to the base 2
Thermal diffusion (emitter diffusion) is performed in B to form an emitter 2E. This highly concentrated EilE 2 Ba can be formed not only by the ion implantation method but also by the thermal diffusion method, if necessary.

The height 71 of the transistor 2 thus formed is located at the portion 2B.
The layer resistance ρS of a is 90 to 110 Ω/mouth, and this value is higher than the specific resistance ρS of the base IB of the conventional equivalent product of 300 to 3
This is about 1/3 compared to 50Ω/mouth.

Regarding the three types of transistors according to the embodiments of the present invention (implemented products 1 to 3) having the above specific resistance values and the three types of conventional transistors (comparative products 1 to 3) also having the above specific resistance values, Then, a reverse bias voltage was applied between emitter E and base B, and the withstand voltage value between emitter and base was measured. This measurement was performed using the measurement circuit TC shown in FIG. This measurement circuit TC connects the switch S to the terminal a side,
Connect the variable voltage DC power supply VE and the capacitor CP,
After charging the capacitor CP, connect the switch S to the terminal side (base a side) and apply a reverse bias voltage between the emitter E and base B of the transistor under test T connected as shown in the figure. be. The measurement was carried out by gradually increasing the voltage value of the DC power supply VE, and the voltage value at which dielectric breakdown occurred between the emitter E and the base B of the test transistor T was determined. The results are shown in Table 1.

Table 1 As is clear from Table 1 above, the withstand voltage values for the reverse bias voltage between the emitter and base of the transistor of this example are approximately twice as high as those of the conventional product, and the transistor of this example It was demonstrated that it has excellent reverse bias voltage resistance.

Source IF and conventional technology - As is clear from the above explanation (by adopting the structure of the present invention for a semiconductor device, the withstand voltage value for the reverse bias voltage between the emitter and base can be increased compared to that of a conventional equivalent product). Therefore, it can be used in circuits where a high reverse bias voltage occurs.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view of a power transistor showing an embodiment of the present invention, FIG. 2 is a reverse bias characteristic/1111 constant circuit diagram thereof, and FIG. 3 is a schematic sectional view of a conventional power transistor. 2...Power transistor 2B...Base 2Ba...High impurity 1 degree part 2C...Collector 2E...Emitter

Claims (1)

[Claims] 1. A semiconductor device having an n-p-n transistor structure, characterized in that at least the vicinity of a corner of a pn junction between a base and an emitter is a high-concentration region having a higher impurity ion concentration than the rest of the base.