JPH0124939Y2 - - 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 and an N ⁺ type second emitter region 5 forming a second transistor 16 provided on the surface of the substrate 1; 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 end of the first emitter region 3 across the first base region 2.
A first Zener diode 8 ^formed of a second Zener diode 9, an N ⁺ type channel stop region 10 provided around the pellet, a base electrode 11 in ohmic contact with the first base region 2, a first emitter region 3 and a second base region 4. An emitter electrode 13 is in ohmic contact with the second emitter region 5, and a shield electrode 14 has one end in ohmic contact with the channel stop region 10 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 Darlington transistor described above, the first and second Zener diodes 8 and 9 are set to the same Zener voltage, so when the Darlington transistor is connected to the L load, 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 MOS IC would be destroyed.

Therefore, in the present invention, the Zener voltage of the second Zener diode 9 is set to be slightly lower than that of the first Zener diode 8, so that the high voltage generated by the L load flows to the base of the second transistor 16. However, even this structure does not efficiently extract high voltage.

(c) Purpose The present invention was made in view of the above, and an object thereof is to provide a Darlington transistor that completely eliminates the conventional drawbacks.

(d) Configuration The Darlington transistor according to the present invention is the third
As shown in the figure, a semiconductor substrate 2 serving as a common collector area
1, first base and emitter regions 22 and 23 forming the first transistor 33, second base and emitter regions 24 and 25 forming the second transistor 34, and first and second Zener diodes 28. . has been done.

(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 21 serving as a common collector region 36, a P-type first base region 22 forming a first transistor 33 formed by double diffusion on the surface of the substrate 21, and an N ⁺ type first emitter region 23 and first transistor 3
A P-type second base region 24 and an N ⁺ -type second emitter region 2 constituting a second transistor 34 provided by double diffusion on the surface of the substrate 21 adjacent to the P-type second emitter region 2
5, an N-type high concentration region 26 formed by ion implantation of N-type impurities provided on the surface of the substrate 21,
A first Zener diode 28 formed by a P ⁺ type high concentration region 27 that extends from the end of the first emitter region 23 on the surface of the substrate 21, crosses the first base region 22, and reaches the N type high concentration region 26. and a second zener formed by a P ⁺ type high concentration region 27 that extends from the end of the second emitter region 25 over the surface of the substrate 21, crosses the second base region 24, and reaches the N type high concentration region 26. diode 29 and a second
A P-type third base region 30 and an N ⁺ -type third emitter region 31 constituting a third transistor 35 provided by double diffusion on the surface of the substrate 21 adjacent to the transistor 34, and a third emitter region. The third base region 30 extends from the end of the substrate 21 on the surface of the substrate 21.
The third Zener diode 32 is formed by the P ⁺ type high concentration region 27 that crosses the N type high concentration region 26 and reaches the N type high concentration region 26, and the N ⁺ type channel formed during emitter diffusion provided around the pellet. a base electrode 38 of vapor deposited aluminum in ohmic contact with the top region 37 and the first base region 22;
, a first connection electrode 40 extending on the oxide film 39 connecting the first emitter region 23 and the second base region 24, an emitter electrode 41 in ohmic contact with the second emitter region 25, and a third emitter region. a second connection electrode 42 extending over the oxide film 39 connecting the oxide film 31 and the second base region 24; and a shield electrode extending inward over the oxide film 39 with one end in ohmic contact with the channel stop region 37. It is composed of 43.

A feature of the present invention is that a third transistor 35 and a third Zener diode 32 are provided. The third emitter region 31 of the third transistor 35 is connected to the second transistor 3 constituting the rear stage of the Darlington transistor by the second connection electrode 42.
4, and a third Zener diode 32 is formed between the base and collector. The Zener voltage of the third Zener diode 32 is determined by making the protrusion width of the P ⁺ type high concentration region 27 into the N type high concentration region 26 larger than that of the other first and second Zener diodes 28 and 29. Set it as low as 5 to 10V.

According to the above structure, the third transistor 35 is inserted between the collector and base of the second transistor 34 in parallel with the first transistor 33, as shown in the equivalent circuit diagram shown in FIG. 4, and the base is connected to the third Zener diode. 32 to the collector.

In the Darlington transistor of the present invention, during normal operation, the third transistor 35 is in a floating state, and the first transistor 33 is OFF.
When a high voltage is applied to the collector, the base potential of the third transistor 35 is raised through the third Zener diode 32 and turned ON. and third transistor 3
4,35 allows for efficient overtaking.

(F) Effects According to the present invention, the high voltage generated by the L load can be efficiently removed by the third transistor 35 and the third Zener diode 32, so that the preceding drive MOS IC can be reliably protected. It is also useful for preventing output oscillations when used in high-voltage Darlington transistors of about 300 to 350V.

[Brief explanation of the drawing]

FIG. 1 is a sectional view illustrating a conventional example, FIG. 2 is an equivalent circuit diagram thereof, FIG. 3 is a sectional view illustrating the present invention, and FIG. 4 is an equivalent circuit diagram thereof. Explanation of main figure numbers 21 is a semiconductor substrate, 33 is a first transistor, 34 is a second transistor, 35 is a third transistor, 28 is a first Zener diode,
29 is a second Zener diode, and 32 is a third Zener diode.

Claims (1)

[Scope of utility model registration request] A semiconductor substrate of one conductivity type serving as a common collector region, a first base of an opposite conductivity type provided on the surface of the substrate constituting a first transistor, an emitter region of one conductivity type, and the substrate constituting a second transistor. formed of a second base of opposite conductivity type provided on the surface, an emitter region of one conductivity type, a high concentration region of opposite conductivity type provided on the surfaces of at least the first and second base regions, and the common collector region. In the Darlington transistor comprising first and second Zener diodes, a third base of an opposite conductivity type and an emitter region of one conductivity type constituting a third transistor are provided on the surface of the substrate, and at least A third Zener diode is provided which is formed by a high concentration region of opposite conductivity type provided on the surface of the third base region and the common collector region, and a third Zener diode is formed between the third emitter region of the third transistor and the common collector region. A Darlington transistor, characterized in that it is connected to a second base region.