JPH01239877A - Structure for electrostatic measure of integrated circuit - Google Patents

Abstract

PURPOSE:To reduce mutual interaction between separated GND lines and the number of elements used for separation by providing a diode whose one electrode is connected to a first GND line and the other is connected to a second GND line, and connecting the substrate with the first GND line. CONSTITUTION:As a structure for an electrostatic measure of an integrated circuit which has first and second GND lines 1 and 2, a first conduction type substrate 14 and a first diode D1, whose one electrode is connected to the first GND line 1 and the other is connected to the second GND line 2, are provided, and the substrate 14 and the first GND line 1 are connected electrically. For example, the first diode D1 is connected between the GND lines 1 and 2, and static electricity can be bypassed from the second GND line 2 to the first GND line side, and the second diode D2 is made by the connection between the p-type substrate 14 and the GND line 1 so as to enable static electricity to be bypassed from the first GND line side 1 to the second GND line 2 side.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to improvements in electrostatic countermeasure structures for integrated circuits.

(Prior art) In integrated circuit devices, as the degree of integration increases,
Circuit devices that include a mixture of analog and digital circuits are increasingly being used. In such integrated circuit devices, by separating the GND lines of each circuit part,
They are often designed to reduce crosstalk between adjacent GND lines.

Furthermore, as an electrostatic countermeasure device between nine separate GND lines, as shown in the circuit diagram in Figure 5, two
diodes 3 and 4 are connected to the first diodes 3 and 4. Second GND line 1.
A structure in which two phantom transistors are connected in place of a diode, and a structure in which two phantom transistors are connected in place of a diode have been proposed. In the structure of FIG. 5, by using two diodes 3, 4.

Static electricity in both directions between the first GND line 1 and the second GND line 2 is bypassed by the forward voltage of either the diode 3 or 4.

(Problem to be solved by the invention) As mentioned above, since two diodes 3.4 are used, the parasitic capacitance between the two GND lines 1.2 is naturally reduced by one diode. larger than the case. Originally, the first. The purpose of separating the second GND lines 1 and 2 is to reduce mutual differences between the two GND lines. Therefore.

An increase in the parasitic capacitance as described above goes against the reduction of the mutual influence between the two, and an improvement has been sought.

Furthermore, since two diodes or phantom transistors are used, the number of elements increases, which is a hindrance to increasing the integration density.

Therefore, an object of the present invention is to reduce mutual influence between GND lines separated by one.

Another object of the present invention is to provide an electrostatic countermeasure structure for an integrated circuit that can effectively reduce the number of elements used for this purpose.

(Means for Solving the Problems) The present invention provides an anti-static structure for an integrated circuit having first and second GND lines, the substrate being of a first conductivity type, and one pole of the first conductivity type. connected to the GND line of
a first whose other pole is connected to the second GND line;
Equipped with a diode.

The substrate and the first GND line are electrically connected, thereby achieving the above object.

(Function) The present invention has two separated first and second parts. This example is similar to the fifth conventional example in that two diodes are used to bypass static electricity in both directions between the second GND lines. However, in the present invention, a diode region is not specially formed for one diode, and the first diode region is not specially formed for one diode.
For example, by electrically connecting the GND line of the p-type substrate and the second
A diode region naturally formed by an n-type region of a circuit portion connected to a GND line is used. Therefore, the anode is substantially connected to the second GND line, and the anode is connected to the first GND line.
one first whose cathode is connected to the GND line of
By simply configuring diodes, it is possible to achieve the same electrostatic countermeasure effect as the conventional example shown in
Since only the diodes are specially formed, the parasitic capacitance between the two GND lines is also dramatically reduced.

(Embodiment) FIG. 1 is a schematic circuit diagram of an embodiment of the present invention, and FIG. 2 is a sectional view showing a specific structure of this embodiment.

In this embodiment there are two as shown in FIG.

1st. Between the second GND lines 1 and 2, the cathode
The anode is connected to the second GND line 2, and the anode is connected to the second GND line 2.
A first diode D1 connected to is electrically connected. Therefore, from the second GND line 2 to the first GN
It can be seen that static electricity can be bypassed to the D line 1 side.

On the other hand, the integrated circuit of this embodiment has a p-type substrate) 1
4 is used, and the first GND line 1 is electrically connected to the p-type substrate 14 as shown by a temporary connection line 30. and.

By connecting the substrate 14 and the GND line 1, a second diode is naturally formed, as will be explained in detail below, and a diode is formed from the first GND line 1 side to the second GND line 2 side. It is configured so that static electricity can be bypassed.

The surface side of the integrated circuit is covered with a protective film 15 to protect the internal circuit portion, which will be described later. First and second GNDs separated from each other inside this protective film 15
A line 1.2 is formed. 1st. The second GND lines 1 and 2 constitute GND lines of different circuit devices, respectively.

The first GND line 1 is electrically connected to a base diffusion region 17 and an emitter region 18 which are further diffused into an n-type region 16 which is diffused in the substrate 14 .

On the other hand, the second GND line 2 is electrically connected to a p-type base diffusion region 19 formed in the n-type region 16. Further, in the circuit on the second GND line 2 side, a hot side line 23 is electrically connected to an emitter region 22 which is diffused into an n-type region with nine isolation regions 20 in between. In addition.

Reference numerals 25 to 29 indicate SiO□ layers.

In FIG. 2, the n-type region 16 and the p-type base diffusion region 19 constitute the first diode DI shown in FIG. That is, this p-type base diffusion region 1
9 is specially formed to form the first diode D1 in FIG.

On the other hand, as mentioned above, the 10th GND line 1.

It is electrically connected to the substrate 14.

Then, this p-type substrate 14 and the second GN
A second diode D2 is naturally formed by the n-type region 21 in the circuit portion on the D line 2 side. This n-type region 21 can be constituted by a resistor island in the circuit portion on the second CHD line 2 side, a collector region of an NPN transistor, or the like.

The second diode D2 using the substrate 14 described above will be explained in more detail with reference to FIGS. 3 and 4.

In FIG. 3, one-circuit devices A and B each have C
, NDD line, 2, and corresponds to the circuit portion configured on the left and right sides of the dashed-dotted line C in FIG. 2 as a boundary. Then, the first GND line 1 and the second GND line 1
A first diode D1 is formed between the ND line 2 and the base diffusion region 19 and the n-type region 16 described above.

Between both GND lines, the cathode is connected to the first GND line 1.
, an anode is inserted so as to be connected to the second GND line 2.

On the other hand, in the circuit shown as an example in the circuit device B on the second GND line 2 side, an NPN transistor Q1 and resistors R+, R2, and R3 are connected. Hot side line 23 and GND line 2 like resistors R and R2
Each resistor island of the resistor R3 that is connected in series between the resistor R3 and the resistor R3 that is not directly connected to the hot side line 23 is +
It is reverse biased by the Vcc2 voltage.

Furthermore, there is a transistor such as the transistor Q1 in which the collector of an NPN transistor is connected to the hot side line.

When the circuit device B as described above is configured on the second GND line 2 side, since the first GND line 1 is electrically connected to the p-type substrate 14, each resistor island Alternatively, a second diode D2 with N as the collector of the transistor Q is naturally formed.

Note that the resistors R, -R3 and the transistor Q1 in the circuit device B described above are merely examples, and are not limited to these. can also be used to configure the second diode D2.

On the other hand, the first diode DI can be formed in a region having a size of 60 μm×80 μm, for example, as shown in a plan view in FIG. In addition, the reference numeral 51 in FIG.
．． 52 are the first and second GND lines 1, respectively.
, 2 are shown.

In the above embodiment, two or more diodes are formed, but the electrostatic withstand voltage is the electrostatic withstand voltage of each terminal in the same power supply system and the electrostatic withstand voltage between each terminal in different power supply systems. Therefore, if the electrostatic withstand voltage between the same power supply systems is made high enough,
Due to the effect of the two diodes, the electrostatic withstand voltage between different power supply systems can also be increased.

(Effects of the Invention) As described above, according to the two present inventions, by electrically connecting the first CHD line to the substrate of the first conductivity type, the substratum is naturally connected without configuring a diode. A second diode can be configured by the straight and the hot side on the second GND line side. Therefore,
1 between the first GND line and the second GND line
By simply forming two first diodes, an electrostatic countermeasure structure for an integrated circuit is provided that can effectively reduce mutual influence between both GND lines without increasing parasitic capacitance. Since it is only necessary to specially configure one diode, the number of elements can be halved compared to the conventional configuration of two diodes, making it possible to increase the integration density.

4. P in figure. Figure 1 is a schematic circuit diagram for explaining one embodiment of the present invention, Figure 2 is a sectional view for explaining the embodiment of Figure 1, and Figure 3 is a schematic diagram of the embodiment of Figure 2. FIG. 4 is a schematic plan view for explaining the first diode, and FIG. 5 is a circuit diagram for explaining a conventional electrostatic countermeasure structure.

DESCRIPTION OF SYMBOLS 1... First GND line, 2... Second GND line, 14... P type substrate, Dl... First
diode, D2... second diode.

that's all

Claims (1)

[Claims] 1. A static electricity countermeasure structure for an integrated circuit having first and second GND lines, the substrate having a first conductivity type, and one pole connected to the first GND line and the other pole connected to the first GND line. An electrostatic countermeasure structure for an integrated circuit, comprising a first diode connected to the second GND line, and the substrate and the first GND line are electrically connected.