JPH0342680Y2 - - Google Patents

Description

[Detailed description of the invention] (a) Industrial application field The present invention relates to an improvement of a Darlington transistor, particularly a Darlington transistor incorporating a Zener diode for protection.

(b) Prior Art As shown in FIG. 1, a conventional Darlington transistor includes an N-type silicon semiconductor substrate 1 forming a common collector region, and a P-type first transistor 15 provided on the surface of the substrate 1. A base region 2 and an N ⁺ type first emitter region 3, a P type second base region 4 provided on the surface of the substrate 1 and constituting the second transistor 16, and an N ⁺ type second
A first emitter region 5 formed by an N type high concentration region 6 provided on the surface of the substrate 1 and a P ⁺ type high concentration region 7 extending from the first emitter region 3 across the first base region 2. Zener diode 8, similarly N-type high concentration region 6 and second emitter region 5 to second
A second Zener diode 9 formed by a P ⁺ type high concentration region 7 extending across the base region 4
, an N ⁺ type channel stop region 10 provided around the pellet, a base electrode 11 in ohmic contact with the first base region 2, and a connecting electrode 1 connecting the first emitter region 3 and the second base region 4.
2, an emitter electrode 13 in ohmic contact with the second emitter region 5, and a channel stop region 1.
The shield electrode 14 has one end in ohmic contact with the shield electrode 14 and extends inward.

The Darlington transistor having the above structure has a Darlington connected first transistor as shown in FIG.
A first Zener diode connected between the transistor T _r1 and the second transistor T _r2 and the bases and collectors of the first and second transistors T _r1 and T _r2 .
The circuit configuration consists of Z _D1 and a second Zener diode Z _D2 .

In the above Darlington transistor, the first and second Zener diodes 8 and 9 are set to the same Zener voltage, so when an L load is connected to the Darlington transistor, the high voltage generated at the L load is applied to the first Zener diode 8. There was a risk that the previous stage drive MOSIC could be destroyed.

(c) Purpose The Darlington transistor according to the present invention is the third
As shown in the figure, a semiconductor substrate 22 of one conductivity type which becomes a common collector region 21, and first base and emitter regions 23 and 2 which constitute a first transistor 37 are shown.
4, second base and emitter regions 25 and 26 constituting the second transistor 38, a high concentration region 27 of one conductivity type provided on the surface of the substrate 22 adjacent to the second base region 25, and a first base A first Zener diode 29 is formed of the common collector region 21 and a high concentration region 28 of opposite conductivity type provided on the surface of the region 23 and reaches the common collector region 21; and a high concentration region of one conductivity type provided on the surface of the second base region 25. Area 2
A second Zener diode 30 is formed of a high concentration region 28 of opposite conductivity type reaching 7 and a high concentration region 27 of one conductivity type, a base electrode 31 connection electrode 32 and an emitter electrode 33, A feature is that the Zener voltage of the diode 29 is set higher than that of the second Zener diode 30.

(E) Example The Darlington transistor according to the present invention is the third example.
As shown in the figure, an N-type silicon semiconductor substrate 22 serving as a common collector region 21, and a first transistor 37 in the previous stage formed by double diffusion on the surface of the substrate 22.
P-type first base region 23 and N ⁺
The first emitter region 24 of the type and the second transistor 38 of the second stage, which is provided by double diffusion on the surface of the substrate 22 adjacent to the first transistor 37, are
type second base region 25 and N ⁺ type second emitter region 26; 1 emitter area 24
The first base region 2 extends over the surface of the substrate 22 from the end.
The first Zener diode 29 is formed of the common collector region 21 and a P ⁺ type high concentration region 28 by selective diffusion that crosses the common collector region 21 and crosses the second emitter region 26.
N extending across the surface and across the second base region 25
P ⁺ due to selective diffusion reaching the high concentration region 27 of the mold
A second Zener diode 30 is formed by a type high concentration region 28 and an N type high concentration region 27, and an emitter provided around the pellet is formed during diffusion.
an N ⁺ type channel stop region 34 , a base electrode 31 of vapor-deposited aluminum in ohmic contact with the first base region 23 , and a first emitter region 24 .
and the oxide film 3 connecting with the second base region 25
connection electrode 3 of vapor-deposited aluminum extended over 5;
2, an emitter electrode 33 in ohmic contact with the second emitter region 26, and a shield electrode 36 having one end in ohmic contact with the channel stop region 34 and extending inwardly over an oxide film 35.

The feature of the present invention is that the Zener voltage of the first Zener diode 29 is determined by the PN junction formed by the first P ⁺ type high concentration region 28 and the low concentration common collector region 21, and the impurity concentration of the common collector region 21 is low. Using this fact, the second Zener diode 30
It is set higher. That is, the second Zener diode 30 is formed by a PN junction between the N type high concentration region 27 and the P ⁺ type high concentration region 28, and the concentration of both is approximately
It is set to have a Zener voltage of 60V. At this time, the Zener voltage of the first Zener diode 29 becomes approximately 120 to 130V.

According to the above structure, the high voltage generated by the L load flows through the second Zener diode 30 and the second
Flows to the base of transistor 38.

(f) Effects According to the present invention, simply by selectively providing the N-type high concentration region 27 adjacent to the second base region 25,
It is possible to protect drive ICs while retaining conventional protection functions. As a result, the present invention is most suitable for switching transistors with large L loads.

[Brief explanation of the drawing]

FIG. 1 is a sectional view illustrating a conventional example, FIG. 2 is an equivalent circuit diagram, and FIG. 3 is a sectional view illustrating the present invention. Explanation of main drawing numbers 21 is the common collector area, 2
2 is a semiconductor substrate; 23 and 24 are first base and emitter regions that constitute the first transistor 37; 25 and 26 are second base and emitter regions that constitute the second transistor 38; and 29 and 30 are the first and emitter regions that constitute the second transistor 38; 2 Zener diodes, 27 is an N type high concentration region, and 28 is a P ⁺ type high concentration region.

Claims (1)

[Scope of utility model registration request] a semiconductor substrate of one conductivity type serving as a common collector region; a first base and emitter region provided on the surface of the substrate constituting a first transistor;
a second base and emitter region provided on the surface of the substrate adjacent to the first transistor and constituting a second transistor; and a height of one conductivity type provided on the surface of the substrate adjacent to the second base region. a first Zener diode formed of a concentration region, a high concentration region of an opposite conductivity type reaching from the first base region to the common collector region, and the common collector region; a second Zener diode formed of a high concentration region of the opposite conductivity type reaching the high concentration region and the high concentration region of the one conductivity type;
A Darlington transistor comprising a connecting electrode connecting a base region.