JPH03139121A - Semiconductor device - Google Patents

Abstract

PURPOSE:To improve the electrostatic breakdown voltage of a line terminal by inserting a resistor into the source electrode side of a transistor. CONSTITUTION:The part between drain electrode D and source electrode S is connected between line terminal 3 and earth terminal 4, and a resistor 5 is inserted to the source electrode S side of a transistor Q1 connecting a gate electrode G with the source electrodes S connection side of the line terminal 3 and earth terminal 4. Therefore, when overvoltage is applied to the line terminal 3 by this resistor 5, it is possible to reduce electric current flowing between the drain electrode D and source electrode S of the transistor Q1. Thus, the strength against overvoltage of the transistor Q1 constituting a protection network can be improved so that the electrostatic breakdown voltage of the line terminal 3 is improved too.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor device equipped with a protection circuit for protecting a functional circuit from overvoltage.

[Background Art] In recent years, due to the miniaturization of semiconductor elements accompanying the increase in the integration and capacity of semiconductor devices, there is a tendency for the electrostatic breakdown voltage of input signal terminals and power supply terminals of semiconductor devices to decrease. For this reason, there is an increasing need to introduce protection means for input signal terminals and power supply terminals suitable for highly integrated semiconductor devices.

FIG. 7 is a configuration diagram of a conventional semiconductor device. As shown in FIG. 7, the semiconductor device includes a functional circuit 1 including a transistor Q3, a transistor Q4, etc., and a protection circuit 8 for protecting the functional circuit 1 from overvoltage.

The drain electrode of the transistor Q1 constituting the protection circuit 8 is connected to the power supply terminal 3, and the source electrode S and gate electrode G are connected to the ground terminal 4.

Note that this transistor Q1 is an N-channel type.

When an overvoltage is applied to the power supply terminal 3, the protection circuit 8 absorbs this overvoltage and protects the functional circuit 1 by connecting the power A terminal 3 and the ground terminal 4 with low impedance using the transistor Q1. As a result, the electrostatic breakdown voltage of the power supply terminal 3 is increased.

[Problems to be Solved by the Invention] However, due to the transistor Q constituting such a protection circuit 8, when an overvoltage is applied, the transistor Q,
When a current is caused to flow between the drain voltage iD and the source electrode B115 by breaking down between the drain voltage iD and the source electrode S, if this current value exceeds the allowable value of the transistor Q1, the transistor Q1 will be thermally destroyed. As a result, the functional circuit 1 may also be destroyed.

(Means for Solving the Problem) The semiconductor device according to claim (1) has a drain electrode and a source electrode connected between a power terminal and a ground terminal, and a drain electrode and a source electrode connected to each other between a power terminal and a ground terminal. In the semiconductor device 1 including a protection circuit including a transistor having a gate electrode connected thereto, the semiconductor device according to claim 2, further comprising a resistor on the source electrode side of the transistor, has a resistor between an input signal terminal and a ground terminal. In a semiconductor device including a protection circuit including a transistor in which a drain electrode and a source electrode are connected and a gate electrode is connected to a source electrode connection side of an input signal terminal and a ground terminal, a resistor is inserted on the source electrode side of the transistor. .

[Function] According to the semiconductor device according to claim (1), the drain electrode and the source electrode are connected between the power supply terminal and the ground terminal, and the gate electrode is connected to the source electrode connection side of the power supply terminal and the ground terminal. In such a transistor, since a resistor is inserted on the source electrode side of the transistor, the resistor can reduce the current flowing between the drain electrode and the source electrode of the transistor when an overvoltage is applied to the power supply terminal.

According to the semiconductor device according to claim (2), the drain electrode and the source electrode are connected between the input signal terminal and the ground terminal, and the gate electrode is connected to the source electrode connection side of the input signal terminal and the ground terminal. In a transistor, since a resistor is inserted on the source electrode side of the transistor, this resistor can reduce the current flowing between the drain electrode and the source electrode of the transistor when an overvoltage is applied to the input signal terminal.

[Example] An example of the semiconductor device according to claim (1) will be described with reference to the drawings.

FIG. 1 is a configuration diagram showing a first embodiment of a semiconductor device according to claim (1). As shown in FIG. 1, the semiconductor device includes a functional circuit 1 and a protection circuit 2, each of which includes a transistor Q3, a transistor Q4, and the like.

A drain electrode of a transistor Q1 constituting the protection circuit 2 is connected to a power supply terminal 3, a gate electrode G is connected to a ground terminal 4, and a source electrode S is connected to the ground terminal 4 via a resistor 5. Note that this transistor Q1 is an N-channel type.

In a semiconductor device equipped with such a protection circuit 2, when an overvoltage is applied to the power supply terminal 3, the transistor Q constituting the protection circuit 2 connects the power supply terminal 3 and the ground terminal 4 with low impedance. , protects the functional circuit 1 from overvoltage by absorbing this overvoltage. At this time, the resistor 5 reduces the current flowing between the drain electrode D and the source electrode S of the transistor Q1.

FIG. 2 is a diagram showing the relationship between the voltage applied to the transistor Q and time in the first embodiment described in claim (1). ■
indicates an overvoltage applied to the transistor Q1, ■ indicates a potential change at the drain electrode, ■ indicates a potential change at the source electrode S, and ■ indicates a potential change between the drain potential JiD and the source electrode S.

As shown in FIG. 2, when an overvoltage is applied to the transistor Q (■), the potential of the drain electrode (■) and the potential of the source electrode S (■) also change accordingly. The reason why the potential of the source electrode S changes is because a potential is generated in the resistor 5 connected to the source electrode S. Therefore, the potential change (2) between the drain electrode and the source electrode S of the transistor Q1 is obtained by subtracting the potential change (2) at the source electrode S from the potential change (2) at the drain electrode.

When an overvoltage is applied to the transistor Q constituting the protection circuit 8 of the conventional semiconductor device, since no resistor is connected to the source electrode Is, the potential of the source electrode S is as follows.
It is considered to be equivalent to the ground terminal 4. Therefore, the potential between the drain electrode D and the source electrode S of the conventional transistor Q is shown as ■ in the second leap.

That is, the drain electrode D of the transistor Q1 of the embodiment
The potential ■ between the source electrode S is considerably reduced compared to the potential between the drain electrode iD and the source electrode Is of the conventional transistor Q.

The reason why the overvoltage (2) applied to the transistor Q1 and the potential change (2) at the drain electrode do not match is due to the delay effect caused by the resistance of the wiring itself and stray capacitance.

Next, in the third article, the drain electrode D/source of the transistor Q constituting the protection circuit 2 of the first embodiment described in claim (1) and the transistor Q constituting the conventional protection circuit 8 when an overvoltage is applied. FIG. 3 is a diagram showing the relationship between the current flowing between electrodes S and time. a shows a change in the current flowing between the drain electrode D and the source electrode S of the conventional transistor Q, and b shows a change in the current flowing between the drain electrode D and the source electrode S of the transistor Q of the embodiment.

As is clear from the third part, the transistor Q of the example,
It can be seen that the peak value of the current flowing between the drain electrode D and the source electrode S is considerably reduced compared to the peak value of the current flowing between the drain electrode D and the source electrode S of the conventional transistor Q1.

In this way, by inserting the resistor 5 between the source electrode S of the transistor Q1 constituting the protection circuit 2 and the ground terminal 4, and reducing the current flowing between the drain electrode D and the source electrode S, the transistor Q, It is possible to increase the withstand capacity against overvoltage.

FIG. 4 is a configuration diagram showing a second embodiment of the semiconductor device according to claim (1). As shown in FIG.
The gate electrode G of the transistor Q2 constituting the transistor Q2 is connected to the power supply terminal 3, and the source electrode S is connected to the power supply terminal 3 through the resistor 5.
and connect the drain electrode to the ground terminal 4. Note that this transistor Q2 is a P-channel type.

Such a protection circuit 6 is connected to the power supply terminal 3 similarly to the protection circuit 2.
If overvoltage is applied to the power terminal 3 and ground terminal 4,
This overvoltage can be absorbed by making a low impedance connection between the two. An embodiment of the semiconductor device according to claim (2), in which the resistor 5 is characterized by a current flowing between the drain electrode and the source electrode S of the transistor Q, will be described with reference to the drawings.

FIG. 5 is a configuration diagram showing a first embodiment of a semiconductor device according to claim (2). As shown in FIG.
The drain electrode of the transistor Q constituting the transistor Q is connected to the input signal terminal 7, the gate electrode G is connected to the ground terminal 4, and the source electrode S is connected to the ground terminal 4 via the resistor 5. Note that this transistor Q is an N-channel type.

FIG. 6 is a configuration diagram showing a second embodiment of the semiconductor device according to claim (2). As shown in FIG.
The gate electrode G of the transistor Q2 constituting the transistor Q2 is connected to the input signal terminal 7, the source electrode S is connected to the input signal terminal 7 via the resistor 5, and the drain electrode is connected to the ground terminal 4. Note that this transistor Q2 is a P-channel type.

Such a protection circuit 2. The protection circuit 6 is connected to the human power signal terminal 7
When overvoltage is applied to input signal terminal 7 and ground terminal 4
This overvoltage is absorbed and the functional circuit 1 is protected from the overvoltage by connecting with a low impedance between them. At this time, the resistor 5 is connected to the transistor Q1 and the transistor Q2.
This is to reduce the current flowing between the drain electrode D and the source electrode S.

Note that in this embodiment, transistors Q1 . Although there is one transistor Q2, there may be a plurality of transistors.

〔Effect of the invention〕

According to the semiconductor device according to claim (1), in a transistor in which a drain electrode and a source electrode are connected between a power supply terminal and a ground terminal, and a gate electrode is connected to the source electrode connection side of the power supply terminal and the ground terminal. Since a resistor is inserted on the source electrode side of the transistor, this resistor can reduce the current flowing between the drain electrode and the source electrode of the transistor when an overvoltage is applied to the power supply terminal. As a result, the overvoltage resistance of the transistors forming the protection circuit can be increased, the electrostatic breakdown voltage of the power supply terminal of the semiconductor device can be increased, and the functional circuit can be protected.

According to the semiconductor device according to claim (2), the transistor has a drain electrode and a source electrode connected between an input signal terminal and a ground terminal, and a gate electrode connected to the source electrode connection side of the power supply terminal and the ground terminal. In this case, since a resistor is inserted on the source electrode side of the transistor, this resistor can reduce the current flowing between the drain electrode and the source electrode of the transistor when an overvoltage is applied to the input signal terminal. As a result, the overvoltage resistance of the transistors that make up the protection circuit can be increased.
It is possible to increase the electrostatic breakdown voltage of the input signal terminal of a semiconductor device and protect the functional circuit.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a first embodiment of the semiconductor device according to claim (1), and FIG. 2 is a diagram showing the relationship between voltage applied to the transistor Q and time of the first embodiment. FIG. 3 shows a transistor Q constituting the protection circuit 2 of the first embodiment and a transistor Q constituting the conventional protection circuit 8.
FIG. 4 is a diagram showing the relationship between the current flowing between the drain electrode D and the source electrode S and time when an overvoltage of 1 is applied. FIG. 4 is a configuration diagram showing the second embodiment, and FIG. FIG. 6 is a block diagram showing a first embodiment of the described semiconductor device, FIG. 6 is a block diagram showing a second embodiment, and FIG. 7 is a block diagram showing a conventional semiconductor device. 3...Power terminal, 4...Ground terminal, 5...Resistor,
7...Input signal terminal, Ql...Transistor (N channel type), Q2...Transistor [P channel type], G...Gate electrode, D...Drain electrode, S
... Source electrode - 1 Figure 3 - Mio Mizute 4 - Tsubakige Shimajo 5 - Kamei 71 - Enter Pufui 1 Jij Ima stand 5 Ruichi Q1 - 1 - One system 2nd Zuzuzugin Tomoji-Kou

Claims (2)

[Claims] (1) In a semiconductor device equipped with a protection circuit including a transistor in which a drain electrode and a source electrode are connected between a power terminal and a ground terminal, and a gate electrode is connected to the source electrode connection side of the power terminal and the ground terminal, A semiconductor device characterized in that a resistor is inserted on the source electrode side of the transistor. (2) A semiconductor device equipped with a protection circuit including a transistor in which a drain electrode and a source electrode are connected between an input signal terminal and a ground terminal, and a gate electrode is connected to the source electrode connection side of the input signal terminal and ground terminal. 2. A semiconductor device according to claim 1, wherein a resistor is inserted on the source electrode side of the transistor.