JPH03209759A - Semiconductor device - Google Patents

Abstract

PURPOSE:To relieve current density of a contact window when a current is biased in a specified window, and remarkably improve electrostatic breakdown strength, by making the contact hole, which a surge current passes, sufficiently large. CONSTITUTION:A contact window 15 has an area 4 times as large as the smallest contact window out of contact windows except the contact window group existing on input terminal nodes and the contact window group existing on transistor source nodes. When a surge being the transient negative maximum current is applied to an input terminal, a diffusion layer under polysilicon 14 forms a channel being the carrier path. A current flows from an aluminum wiring 11 connected with an input terminal to an aluminum wiring 12 of earth potential via the contact windows 15. Since the contact window which the surge current passes is as large as 4 times or more, the current density of a contact window is relieved even if the current is biased on a specified window. Hence the electrostatic breakdown strength is remarkably improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor device having a contact window-shaped semiconductor integrated circuit with high resistance to electrostatic discharge damage.

[Prior Art] Conventionally, a protection circuit has been provided in the input/output portion of a semiconductor integrated circuit in order to obtain resistance to electrostatic discharge damage. Below is an example of a conventional input protection circuit for a semiconductor integrated circuit.
This will be explained based on FIG.

In Figure 2, 1 is an aluminum wire connected to the input terminal,
Reference numeral 2 indicates an aluminum wiring at a ground potential, 3 a diffusion layer, 4 polysilicon, and 5 a contact window.

The operation of the input protection circuit for the semiconductor integrated circuit configured as described above will be described below.

First, when a negative transient maximum current surge is applied to the input terminal (not shown), the diffusion layer under the polysilicon 4 forms a channel, which is a carrier path, and is connected to the input terminal. A current is generated from the aluminum wiring 1 at the ground potential to the aluminum wiring 2 at the ground potential through the contact window 5.

Furthermore, when a positive surge is applied to the input terminal, a punch-through current that occurs when the energy barrier between the emitter and the base is sufficiently lowered by the collector-emitter voltage flows in a path in the opposite direction to that described above.

Therefore, the surge applied to the input terminal can flow into the aluminum wiring 2 at ground potential through the input protection circuit, so that the internal circuit is protected.

Similarly, in the output protection circuit, due to the punch-through current of the transistor whose drain is the output terminal node,
Since the surge can flow into the aluminum wiring 2 at ground potential or the aluminum wiring at power supply voltage potential, the internal circuit is protected.

[Problems to be Solved by the Invention] However, in the configuration of conventional semiconductor integrated circuits, with the miniaturization of pattern rules in recent years, the area of contact windows through which surges pass has become smaller, and each contact window is Because they are not in a symmetrical positional relationship, a certain contact among the contact windows that are on the same node as the input/output terminal, or the contact window group that is on the same node as the source of the transistor whose drain is this node. There has been a problem in that the current tends to be biased toward the window, and the specific contact window is easily destroyed.

The present invention solves the problems of the prior art, and aims to provide a semiconductor integrated circuit having a contact window shape with high resistance to electrostatic discharge damage.

[Means for Solving the Problems] In order to achieve the above object, the present invention has the following configuration. In other words, the present invention provides a contact window group located at the same node as an input terminal or an output terminal, or a contact window group located at the same node as a source of a transistor whose drain is the node of the input terminal or output terminal, or all of them. is the area of the contact window with the smallest area among the contact windows other than all the contact windows mentioned above.
This is a semiconductor device characterized by having an area more than twice as large.

[Function] According to the configuration of the present invention described above, since the contact window through which the surge current passes is sufficiently large, even if the current is biased toward a certain contact window, the current density in the contact window is relaxed, and electrostatic damage is prevented. The resistance is significantly higher [Example] The present invention will be explained in more detail below using an example. Note that the present invention is not limited to the following example.

FIG. 1 shows one embodiment of the present invention. That is, FIG. 1 is a plan view of a semiconductor integrated circuit according to the present invention, in which 11 is an aluminum wiring connected to an input terminal, 12 is an aluminum wiring at ground potential, 13 is a diffusion layer, 14 is polysilicon, and 15 is a contact window. It shows.

The contact window 15 has the smallest area among the contact windows other than the contact window group located at the node of the input terminal or the contact window group located at the source node of the transistor whose drain is the input terminal node. It is assumed that the area is more than four times the area of the area.

Next, the operation of the input protection circuit configured as described above will be explained.

First, when a negative transient maximum current surge is applied to the input terminal (not shown), the diffusion layer under the polysilicon 14 forms a channel, which is a carrier path, and is connected to the input terminal. A current is generated through the contact window 15 from the aluminum wiring 11 at the ground potential to the aluminum wiring 12 at the ground potential.

Furthermore, when a positive surge is applied to the input terminal, a punch-through current that occurs when the energy barrier between the emitter and the base is sufficiently lowered by the collector-emitter voltage flows in a path in the opposite direction to that described above.

Therefore, the surge applied to the input terminal can flow into the aluminum wiring 12 at ground potential through the input protection circuit, so that the internal circuit is protected.

Similarly, in the output protection circuit, due to the punch-through current of the transistor whose drain is the output terminal node,
Since the surge can flow into the aluminum wiring 12 at ground potential or the aluminum wiring 11 at power supply voltage potential, the internal circuit is protected. And, since the contact window through which the surge current passes is sufficiently large, at least four times as large, even if the current is biased toward a specific contact window, the current density in the contact window is relaxed, and the resistance to electrostatic damage is significantly high. becomes.

On the other hand, the contact window through which the surge current passes is 4.
If it is less than twice that, the current tends to be concentrated in a certain contact window, and the current density of the contact window tends to exceed and destroy it, which is not preferable.

In the embodiment of the present invention, an input protection circuit is taken as an example, but
The same applies to output protection circuits.

[Effects of the Invention] As described above, according to the present invention, the contact window through which the surge current passes is sufficiently large, so even if the current is biased toward a certain contact window, the current density in the contact window is relaxed, and the current density in the contact window is relaxed. It is possible to achieve the effect that electrical breakdown resistance is significantly increased.

[Brief explanation of drawings]

FIG. 1 is a plan view of a semiconductor integrated circuit according to an embodiment of the present invention, and FIG. 2 is a plan view showing a conventional example. 1.11... Aluminum wiring connected to input terminal 2...
Aluminum wiring at ground potential 3...Diffusion layer 4...Polysilicon 5...Contact window Fig. 1 Fig. 2

Claims (1)

[Claims] (1) Any or all of the contact windows located at the same node as the input terminal or output terminal, or the contact windows located at the same node as the source of the transistor whose drain is the node of the input terminal or output terminal, A semiconductor device characterized in that the semiconductor device has an area that is four times or more the area of the smallest contact window among the contact windows other than all the contact window groups.