JP2633831B2 - Bipolar semiconductor integrated circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] The present invention relates to a bipolar semiconductor integrated circuit, in which a protection element is provided between a power supply terminal and a base of a bipolar transistor connected to the power supply terminal. Prevents destruction of the circuit due to negative static electricity.

[Industrial applications]

The present invention relates to a bipolar semiconductor integrated circuit, and more particularly, to a bipolar transistor which operates by a current flowing through a PN junction and a bipolar semiconductor integrated circuit using a diode or the like.

The bipolar semiconductor integrated circuit has a structure as shown in FIG. In the drawing, an n ⁺ -type buried layer 11 is formed on a P-type substrate 10, and n-type element formation regions 12, 13, and 14 are formed thereon by epitaxial growth. Element formation area 12-14
Each is separated by a P ⁺ -type element isolation region 15. The substrate 10 is grounded.

The element forming region 12 is provided with a P-type region 16 and n ⁺ regions 17 and 18, and an NPN transistor having electrodes 19, 20 and 21 attached thereto as base, collector and emitter is formed. The element forming region 13 includes an n ⁺ type region 23,
P-type regions 23 and 24 are provided, and electrodes 2 attached to these
A lateral PNP transistor having 5, 26, and 27 bases, emitters, and collectors, respectively, is configured. A P-type region 28 is provided in the element forming region 14, and electrodes 29, 30 at both ends thereof are provided.
The resistance is configured by attaching. An electrode 32 for setting the potential of the element forming region 14 is provided in the n ⁺ type region 31.
33 is an insulating layer.

In the above bipolar semiconductor integrated circuit, the power supply voltage +
The electrodes that can be connected to the power supply terminal to which Vcc is applied are the base (electrode 19) and the emitter (electrode 21) of the NPN transistor
And the emitter of a lateral PNP transistor (electrode 26)
And a collector (electrode 27) and a resistor element formation region (electrode
32).

This is, for example, the collector of an NPN transistor (electrode 2
0) is connected to the power supply terminal, and when the power supply of the semiconductor integrated circuit is erroneously reversely connected, n
This is because a large current flows in the forward direction to the element forming region 12 of the mold, and the semiconductor integrated circuit is destroyed.

In contrast, the emitter of NPN transistor (electrode 2
If 1) is connected to the power supply terminal, no current flows between the substrate 10 and the emitter (electrode 21) even if the power supply is reversely connected by mistake.

[Conventional technology]

FIG. 4 shows a circuit diagram of an example of a conventional semiconductor integrated circuit. In the figure, a power supply terminal 40 to which a power supply voltage + Vcc is applied has a lateral PNP transistor Tr ₁ , T
The emitters of r ₂ and Tr ₃ are connected. Also, terminal 41
Is grounded.

The transistors Tr ₁ , Tr ₂ and Tr _{3 form} a current mirror circuit, and perform a constant current output operation according to the bias of the transistor Tr ₄ and the resistor R ₁ . S transistor Tr _5, Tr ₆ husband constitute a differential amplifier circuit, the transistor Tr _2, and is supplied with operating current by a constant current source diode D ₂ and transistor Tr ₉ of the current mirror configuration. Transistor
The output signal extracted from the collector of Tr ₆ is amplified by transistor Tr ₈ and then output from terminal 44 via open-collector transistor Tr ₇ . Accordingly, this circuit, the base of the transistor Tr ₅ is set to the non-inverting input terminal 42, a differential amplifier circuit the base of the transistor Tr ₆ is an inverting input terminal 43.

[Problems to be Solved by the Invention] However, in the circuit shown in FIG. 4, when negative high-voltage static electricity enters the power supply line, the transistors Tr ₁ , Tr ₂ , Tr
_{When a} reverse voltage exceeding the breakdown voltage is applied to the PN junction between the n-type element forming region 13 and the P-type region 23 of the semiconductor integrated circuit as shown in FIG. There is a problem that a semiconductor integrated circuit is thermally destroyed.

The present invention has been made in view of such a point,
It is an object of the present invention to provide a bipolar semiconductor integrated circuit that has a simple configuration and prevents destruction due to static electricity.

[Means for solving the problem]

The bipolar semiconductor integrated circuit of the present invention is configured using a bipolar element that operates by a current flowing through a PN junction, and a plurality of lateral-structure PNP transistors (Tr ₁ ) are connected to a high-potential-side power supply terminal (40). , Tr ₂ , Tr ₃ ) A bipolar semiconductor integrated circuit that connects each emitter and supplies power to the elements in each part of the circuit from the collector of each of a plurality of lateral PNP transistors (Tr ₁ , Tr ₂ , Tr ₃ ) In a plurality of lateral structure PNP transistors (Tr ₁ , Tr ₂ , T
r ₃ ) comprising a protection element (50) having an NPN transistor having a lower breakdown voltage than that of the protection element (50), and connecting a base having an emitter and a resistance of the NPN transistor in the protection element (50) to the power supply terminal (40). , The collector of the NPN transistor is connected to the base of each of a plurality of laterally structured PNP transistors (Tr ₁ , Tr ₂ , Tr ₃ ).

[Action]

In the present invention, NPN of PNP transistors connected lateral structure to the power supply terminal when the negative static electricity was coming to the power supply terminal _{(Tr 1, Tr 2, Tr} 3) lower protection element having a breakdown voltage than (50) since the reverse current flows between the base and the collector of the transistor, breakdown due to static electricity of the PNP transistor of the connected lateral structure _{(Tr 1, Tr 2, Tr} 3) is prevented in the power source terminal, also protective element (50) By connecting the base of the NPN transistor to the power supply terminal (40) via a resistor, the value of the reverse current flowing between the base and collector of the protection element (50) can be reduced, preventing the protection element (50) from being destroyed. Can be further performed.

〔Example〕

FIG. 1 is a circuit diagram showing one embodiment of a bipolar semiconductor integrated circuit according to the present invention. The circuit shown in FIG. 1 constitutes a differential amplifier circuit, in which the same parts as those in FIG. 4 are denoted by the same reference numerals, and description thereof will be omitted.

In FIG. ₁ , a protection element 50 is connected between a power supply terminal 40 and a commonly connected base of each of the lateral PNP transistors Tr ₁ , Tr ₂ and Tr ₃ .

The protection element 50 is composed of an NPN transistor as shown in FIG. FIG. 2A is a plan view of the protection element 50. FIG. Here, a portion surrounded by a solid line 51 is an element formation region of the protection element 50. A portion surrounded by a solid line 52 of the element forming region is an n ⁺ -type region, the electrode 53 serving as a collector is attached to the n ⁺ -type region.

The portion surrounded by the solid line 54 is a P-type region, and n ⁺
A portion 55a facing the mold region, and n ⁺
A portion 55b extending in a direction away from the mold region, and a portion 55a
And a portion 55c extending in a direction away from the n ⁺ -type region from the other end of. An electrode 56 serving as a base is attached to an end of the portion 55b.

End portion 55c is a portion surrounded by a solid line 57 is a large area with the n ⁺ -type region, the electrode 58 serving as the emitter is attached to the individual n ⁺ -type region.

Therefore, as shown in FIG. 2B, the protection element 50 is an NPN transistor having a resistance at the base, and the electrodes 56, 58
It is used with a common connection between bases and emitters. For this reason, the protection element 50 is substantially equivalent to a diode as shown in FIG.

The breakdown voltage in the reverse direction of the PN junction between the base and collector of the protection element 50 is a lateral PNP type transistor Tr ₁ , Tr ₂ , Tr ₃
It is smaller than the reverse breakdown voltage of the PN junction between each emitter and base and larger than the voltage between the terminals 40 and 41.

As shown in FIG. 1, the protection element 50 has an electrode 53 connected to a common base of the transistors Tr ₁ , Tr ₂ , and Tr ₃ .
The commonly connected electrodes 56 and 58 are connected to the power supply terminal 40.

Here, even when the power supply of the semiconductor integrated circuit is incorrectly reversely connected and the power supply terminal 40 is at the ground level and the power supply voltage + Vcc is applied to the terminal 41, the base and the emitter of the protection element 50 which is an NPN transistor are connected to the terminals. Because the breakdown voltage between the base and the collector is higher than the voltage Vcc, no current flows from the substrate 10 of the semiconductor integrated circuit to the base and the emitter of the protection element 50.

If the power supply terminal 40 power supply voltage + Vcc is applied correctly, the base of the protective element 50, the transistor Tr ₁ via a collector, Tr _2, Tr ₃ current flows to the base of each, but the base of the protective element 50 the resistance Therefore, the above current is very small, and the operation of each of the transistors Tr ₁ , Tr ₂ and Tr ₃ can be regarded as the same as that of FIG.

Here, when static electricity of negative polarity large voltage is mixed into the power supply line, the emitters of the transistors Tr ₁ , Tr ₂ , Tr ₃
A reverse current flows from the collector of the protection element 50 having a lower breakdown voltage than the breakdown voltage between the bases to the base. At this time,
Since the base of the protection element 50 has a resistance, the value of the reverse current is small, so that the collector-base of the protection element 50 is not thermally damaged.

As a result, the transistor Tr connected to the power supply terminal 40
₁ , ₁ , ₂ and ₃ are prevented from being destroyed by static electricity. Further, since the protection element 50 does not suffer thermal damage, the transistors Tr ₁ , Tr ₂ , and Tr ₃ are protected by the above-described operation even if a large amount of negative voltage static electricity enters the power supply line a plurality of times.

〔The invention's effect〕

As described above, according to the present invention, not only the destruction when the power supply is reversely connected but also the destruction due to static electricity entering the power supply terminal is prevented, and the electrostatic withstand capability of the bipolar semiconductor integrated circuit is reduced. It can be high and has no effect on the normal operation of the circuit.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of an embodiment of a bipolar semiconductor integrated circuit according to the present invention, FIG. 2 is a view for explaining a protection element shown in FIG. 1, and FIG. 3 is a cross-sectional view of the bipolar semiconductor integrated circuit. FIG. 4 is a circuit diagram of an example of a conventional circuit. In the figure, 10 is a substrate, 12, 13, 14 are element forming regions, 16, 23, 24, 28 are P-type regions, 17, 18, 22, 31 are n ⁺ -type regions, 19 to 21, 25 to 27. , 29 to 32, 53, 56, 58 are electrodes, 40 is a power supply terminal, and 50 is a protection element.

Claims (1)

(57) [Claims] 1. A high-potential power supply terminal (40) comprising a plurality of lateral PNP transistors (T
r ₁ , Tr ₂ , Tr ₃ ) Bipolar type in which the respective emitters are connected and the collector of each of the plurality of lateral PNP transistors (Tr ₁ , Tr ₂ , Tr ₃ ) supplies power to the elements in each part of the circuit In a semiconductor integrated circuit, the plurality of lateral structure PNP transistors (Tr ₁ , Tr ₂ , T
r ₃ ) comprising a protection element (50) having an NPN transistor having a lower breakdown voltage than that of the protection element (50), and connecting a base having an emitter and a resistance of the NPN transistor in the protection element (50) to the power supply terminal (40). A bipolar semiconductor integrated circuit, wherein a collector of the NPN transistor is connected to a base of each of the plurality of lateral PNP transistors (Tr ₁ , Tr ₂ , Tr ₃ ).