JPH0427151A - Protective circuit for input/output part of semiconductor device - Google Patents

Abstract

PURPOSE:To reduce the area of input/output parts for a semiconductor device, to decrease in size a chip, to reduce the cost of the device and to enhance integration by so providing a protective circuit for the input/output parts as to superpose the circuit under a bonding pad. CONSTITUTION:In input/output parts, a protective circuit 28 is so provided as to be superposed under a bonding pad 30, which is connected to a transistor 32 through the circuit 28. The pad 30 is disposed with an aluminum (Al) second layer interconnection 38 externally through a hole 36 formed at a protective film 34. An aluminum (Al) first interconnection layer 42 is covered with an insulating film 40 under the layer 38. Further, the circuit 28 is provided under the layer 42, and connected to the layer 42.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a protection circuit for an exposed portion of a semiconductor device, which is provided in an input/output portion of a semiconductor device that is connected to an external circuit via a bonding pad.

[Conventional technology]

In semiconductor devices such as semiconductor integrated circuits (LSI),
If a high external overvoltage or overcurrent load is applied to the chip due to static electricity discharge, etc., if the overvoltage is not absorbed, problems may occur, such as malfunction of the semiconductor device or element destruction. be. To prevent such problems from occurring, a protection circuit consisting of resistors, diodes, etc. is usually added to the input/output section on the chip. An example of a planar configuration of a conventional input/output section is shown in FIG.
As shown in the figure, this input/output section includes a bonding wire 1 to connect an external circuit and an internal circuit of the semiconductor device.
A bonding pad 10 for bonding 6, a transistor section 12 provided with transistors for performing various processing on signals input/output via the pad 10, and a transistor section 12 provided between the pad 10 and the transistor section 12. The semiconductor device is configured to include a protection circuit 14 for protecting the semiconductor device from abnormal overvoltage, overcurrent, etc. Note that the reference numeral 16 in the figure is a bonding wire. Here, FIG. 5 shows an enlarged vertical cross-sectional view of the pad 10. As shown in FIG. 5, the conventional pad 10 has a multilayer wiring including, for example, a first aluminum layer and a second aluminum layer. , the peripheries of the wiring An first layer and the Aλ second layer provided on the insulation film 18 are covered with an insulation M20 and a protective film 22. A hole 24 is provided in the A1 second layer upper protective film 22, and the bonding wire 16 is bonded to the A (second layer) through the hole 24.

[Problems to be Solved by the Invention] However, the conventional protection circuit has an area that is 1/3 to 1/4 of the size of the transistor section 12, and is provided at a position different from the bonding pad 10. As a result, the input/output section occupies a large area on the chip of a semiconductor device.Especially in today's semiconductor devices, where there is a remarkable trend toward increasing the number of pins, the area occupied by this input/output section becomes large. There is a problem in that this becomes an obstacle to increasing the degree of integration of semiconductor devices. The present invention has been made in order to solve the above-mentioned problem of the conventional U point, and it is possible to reduce the area of the input/output section and reduce the chip size, thereby reducing the cost and increasing the integration of semiconductor devices. The purpose of the present invention is to provide a protection circuit for an input/output section that can protect the input/output section. [Means for Solving the Problems] The present invention provides a protection circuit provided in an input/output section of a semiconductor device connected to an external circuit via a bonding pad, in which the protection circuit is arranged so as to overlap the lower part of the bonding pad. By providing this, the above problem is solved.

[Effect]

In the present invention, in the protection circuit of the input/output section of the semiconductor device, the protection circuit is provided so as to overlap the lower part of the bonding pad. Therefore, on the chip, the area occupied by the input/output section consisting of the protection circuit and the bonding pad can be reduced compared to when they are provided separately. The area occupied by bonding pads and protection circuits has been reduced by 20-30% compared to the previous version. Therefore, it is possible to reduce the cost and increase the integration of the semiconductor device by reducing the chip size.

【Example】

Embodiments of the present invention will be described in detail below with reference to the drawings. This embodiment is an input/output section provided in a semiconductor device having a planar configuration as shown in FIG. As shown in Figure 1,
In this input/output section, the protection circuit 28 is provided so as to overlap the lower part of the bonding pad 30, and the bonding pad 30 is connected to the transistor section 32 via the protection film #I28. FIG. 2 shows a detailed vertical cross-sectional view of the protection circuit 28 and pad 30. As shown in FIG.
Aluminum (A, e) second layer wiring 3 externally via
8 is coming. The lower part of the second aluminum wiring layer 38 is covered with an insulating film 40 and aluminum (A1
) A first wiring layer 42 is provided. Furthermore, this AJ2
A protection circuit 28 is provided below the first wiring layer 42 and is connected to the AJ2 first wiring layer 42 . In addition, in FIG. 2, the reference numeral 44 is an insulating film, and the reference numeral 46 is a diffusion layer. A circuit example of the protection circuit 28 is shown in FIG. 3. As shown in FIG. 3, the protection circuit 28 consists of a resistor R and a diode D. This resistor R is made of polysilicon (Poly-31
licon> and a diffusion layer. or,
Diode D can be configured with a diffusion layer 46. In this embodiment, as shown in FIG. 1, since the protection circuit 28 is provided below the bonding pad 30, the area occupied by the input/output section on the chip can be reduced by 20 to 30% compared to the conventional one. I can do it. Therefore, since the chip area can be reduced, cost reduction and high integration can be achieved. In the above embodiment, an example of the vertical cross section of the protection circuit and the boarding pad is shown in FIG. Other configurations may be used as long as the circuit is provided below the bonding pad.Also, in Figure 1, the protection circuit is larger than the pad and the entire area of the pad overlaps, but the pad and @protection circuit The size and overlapping ratio are not limited to these, and the effects of the present invention can be obtained even if the protection circuit is small or has only one room. or,
In the embodiment, a two-layer aluminum wiring is used, but the same effect can be obtained in the case of a multilayer wiring of three or more layers.

【Effect of the invention】

As described above, according to the present invention, in a semiconductor device, the area occupied by the input/output section on the chip can be reduced. Therefore, excellent effects such as reducing the chip size of the semiconductor device and achieving cost reduction and higher integration of the semiconductor device can be obtained.

[Brief explanation of drawings]

FIG. 1 is a plan view showing the configuration of an input/output section according to an embodiment of the present invention, FIG. 3 is a circuit diagram showing a configuration example of the protection circuit, FIG. 4 is a plan view showing a configuration example of a conventional input/output section, and FIG. 5 is a circuit diagram of a protection circuit provided in the conventional input/output section. FIG. 2 is a vertical cross-sectional view of a main part showing a detailed configuration example. 8... Protection circuit, 0... Bonding pad, 2... Transistor part, 4... Protective film, 6... Hole, 8... Aluminum second wiring layer, O... Insulation Film, 2... Aluminum first layer wiring layer, 6... Diffusion layer.

Claims (1)

[Claims] (1) In a protection circuit provided in an input/output section of a semiconductor device connected to an external circuit via a bonding pad, the protection circuit is provided so as to overlap the lower part of the bonding pad. Output section protection circuit.