JP2001339051A - Protective circuit for circuit element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the breakage of a circuit element caused by static electricity in the formation process of a transistor element or after its formation, in a semiconductor device where circuit elements such as the above transistor element and a wiring pattern are formed on an insulating substrate. SOLUTION: This is a protective circuit consisting of a protective resistance element 13 being arranged on an insulating substrate 10 equipped with a circuit element and input/output terminals 11 and 12, and connected between the adjacent input/output terminals 11 and 12. The end of the protective resistance element 13 and a part of the input/output terminals 11 and 12 form a protective capacitive element 15 through a gate insulating film 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a protection circuit for a circuit element, and more particularly to a protection circuit for a transistor element and a wiring pattern formed on an insulating substrate.

[0002]

2. Description of the Related Art Conventionally, in a semiconductor device having a circuit element such as a transistor element or a wiring pattern formed on an insulating substrate, such as an array substrate of a liquid crystal display device, the circuit element is destroyed by static electricity in a manufacturing process. In order to prevent this, a protection circuit is provided. In this protection circuit, a resistance element or a diode element is connected as a protection element between the input / output terminals connected to the circuit element to prevent the flow of a current that would destroy the circuit element by dispersing static electricity. is there.

[0003]

Incidentally, since the protective elements such as the resistor element and the diode element are formed in the same step as the transistor element, it is necessary to wait for the formation of the transistor element before the transistor element can function as the protective element. No. For this reason, in the process of forming the transistor element, electrostatic breakdown that occurs between the time when the gate electrode is formed and the time when the source and drain electrodes are formed is prevented.
It did not function as a protection element, and was not an effective means for preventing a reduction in product yield.

[0004] Even after the transistor element is formed, if a large current exceeding the permissible amount of the protection element flows due to static electricity, destruction of the transistor element particularly near the input / output terminal may occur. There was a problem that he could not escape.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a circuit element protection circuit capable of preventing a circuit element from being destroyed by static electricity generated during or after a transistor element is formed.

[0006]

According to a first aspect of the present invention, there is provided a resistive element disposed on a substrate having a circuit element and an input / output terminal connected thereto, and connected between the adjacent input / output terminals. It is a protection circuit for a circuit element consisting of: This protection circuit is characterized in that an end of the resistance element and a part of the input / output terminal are arranged so as to form a capacitance element via an insulating film.

According to a second aspect of the present invention, there is provided a protection for a circuit element comprising a diode element disposed on a substrate having a circuit element and an input / output terminal connected thereto and connected between the adjacent input / output terminals. Circuit. This protection circuit is characterized in that an end of the diode element and a part of the input / output terminal are arranged so as to form a capacitance element via an insulating film.

In a preferred embodiment, the resistance element or the diode element is formed of the same layer as an active layer forming a transistor element.

In a preferred embodiment, the insulating film comprises:
The insulating film is the same as the gate insulating film of the transistor element.

In a further preferred embodiment, the active layer of the transistor element is formed of polysilicon or amorphous silicon.

According to a third aspect of the present invention, in the first or second aspect, an end of the resistance element or the diode element has
For example, a plurality of protrusions having a saw-like shape are formed.

According to a fourth aspect of the present invention, there is provided a protection circuit disposed on a substrate having a circuit element and an input / output terminal connected to the circuit element, wherein an end of the input / output terminal, an active layer of the circuit element, It is characterized in that the resistance elements composed of the same layer are arranged so as to form a capacitance element via an insulating film.

In a preferred embodiment, the other end of the resistance element is disposed so as to overlap with another wiring through an interlayer insulating film having a thickness larger than that of the insulating film. here,
The resistance element and the wiring form a capacitance element via an interlayer insulating film.

According to the first to fourth aspects of the present invention, if static electricity that destroys the gate electrode is generated before the source / drain electrodes of the transistor element (not shown) are formed, the gate electrode of the transistor element is not affected. First, since the resistive element or the diode element, the input / output terminal, and the capacitive element including the insulating film are destroyed by static electricity, high electric field energy of the static electricity is consumed, and the gate electrode is prevented from being destroyed by static electricity. Also, when the transistor element is formed and the protection circuit comes to work,
When a large current exceeding the allowable amount of the resistor element or the diode element flows, the capacitive element is destroyed by the current exceeding the allowable amount, so that high electric field energy of static electricity is consumed. Therefore, the probability that the transistor element is destroyed by static electricity is significantly reduced as compared with the related art.

In particular, according to the structure of the third aspect, the thickness of the insulating film covering the protrusion is partially reduced, and if the shape is acute, a high electric field of static electricity is concentrated on the protrusion. become. Therefore, destruction occurs in a wide range at the end of the resistance element or the diode element, and the high electric field energy of static electricity is further consumed.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which a circuit element protection circuit according to the present invention is applied to an array substrate of a liquid crystal display device will be described below.

In the following embodiments, of the electrode structure formed on the array substrate, only the portion where the protection circuit is formed will be described, and circuit elements such as transistor elements and wiring patterns will be illustrated and illustrated. Description is omitted.

[First Embodiment] FIG. 1 is a schematic view showing an electrode structure of an array substrate according to a first embodiment.
(A) is a schematic plan view showing an electrode structure near an input / output terminal,
FIG. 1B is a schematic cross-sectional view taken along the line aa ′ in FIG.

Input / output terminal 1 formed on insulating substrate 10
Reference numerals 1 and 12 denote a part of a wiring connected to a transistor element (not shown). Both terminals are electrically connected by a protective resistance element 13. The protection resistance element 13 is formed of the same layer as the active layer forming the transistor element, and becomes a resistance element by controlling the amount of impurities to be doped. In the transistor element of this embodiment, the active layer is formed of polysilicon.

The end of the protection resistor 13 and the input / output terminal 11
Are arranged so as to overlap in a plane with the gate insulating film 14 interposed therebetween. Here, an end portion of the protection resistance element 13 and a part of the input / output terminal 11 form a protection capacitance element 15 via a gate insulating film 14. Although not shown in FIG. 1B, the other end of the protection resistance element 13 and a part of the input / output terminal 12 are similarly formed with protection capacitance elements.

An interlayer insulating film 16 is formed on the surfaces of the input / output terminals 11 and the gate insulating film 14, and a wiring 17 on the same layer as the source / drain electrodes of the transistor portion (not shown) is formed thereon. .

The electrode structure of the protective resistance element 13 is formed in the same step as that of the transistor element (not shown).
When the electrode structure is formed, the input / output terminal 1
1 and the protection resistance element 13 are electrically connected, and the protection resistance element 13 functions as a protection element.

In the protection circuit shown in FIG. 1 including the protection resistance element 13 and the protection capacitance element 15, the gate electrode is broken before the source / drain electrodes of the transistor element (not shown) are formed. When such static electricity is generated, the protection capacitance element 15 is destroyed before the gate electrode of the transistor element. At the time of this destruction, high electric field energy of static electricity is consumed, so that destruction of the gate electrode due to static electricity can be prevented. Further, when a large current that exceeds the allowable amount of the protective resistance element 13 flows due to static electricity at the time when the transistor element is formed and the protective resistance element 13 functions as the protection element, the allowable amount is exceeded. The protection capacitance element 15
Is destroyed. Also at this time, the high electric field energy of the static electricity is consumed. Therefore, the probability that the transistor element is destroyed by static electricity is greatly reduced as compared with the related art, and a decrease in yield due to electrostatic breakdown can be prevented.

[Embodiment 2] FIG. 2 is a schematic diagram showing an electrode structure of an array substrate according to Embodiment 2.
(A) is a schematic plan view showing an electrode structure near an input / output terminal,
FIG. 2B is a schematic cross-sectional view taken along the line bb ′ in FIG.

The second embodiment shows an example in which the protection element is constituted by a diode element. The other configuration is the same as that of the first embodiment, and the same reference numerals are given to the same parts.

The input / output terminal 1 formed on the insulating substrate 10
1 and 12 are electrically connected by a protection diode element 18. This protection diode element 18
The diode element is formed by the same layer as the active layer forming the transistor element and by controlling the amount of doped impurities. In the transistor element of this embodiment,
The active layer is formed of polysilicon.

The end of the protection diode element 18 and a part of the input / output terminal 11 are disposed so as to overlap in a plane with the gate insulating film 14 interposed therebetween. Here, an end of the protection diode element 18 and a part of the input / output terminal 11 form a protection capacitance element 19 via the gate insulating film 14. FIG.
Although not shown in (B), the other end of the protection diode element 18 and a part of the input / output terminal 12 are similarly formed with protection capacitance elements.

An interlayer insulating film 16 is formed on the surfaces of the input / output terminals 11 and the gate insulating film 14, and a wiring 17 in the same layer as the source / drain electrodes of the transistor element (not shown) is formed thereon.

The electrode structure according to the second embodiment is also formed in the same step as the transistor element (not shown). When the electrode structure is formed, the input / output terminal 11 and the protection diode element 18 are connected by the wiring 17. The protection diode element 18 is electrically connected and functions as a protection element.

The protection diode element 18 shown in FIG.
In the protection circuit composed of the transistor and the protection capacitance element 19, if static electricity that destroys the gate electrode is generated before the source / drain electrodes of the transistor element (not shown) are formed, Then, the protection capacitance element 19 is destroyed. At this time, since the high electric field energy of the static electricity is consumed, the gate electrode can be prevented from being damaged by the static electricity. When a large current that exceeds the allowable amount of the protection diode element 18 flows at the time when the transistor element is formed and the protection diode element 18 functions as the protection element, the amount exceeding the allowable amount is used. Of the protection capacitance element 19
Is destroyed. Also at this time, the high electric field energy of the static electricity is consumed. Therefore, the probability that the transistor element is destroyed by static electricity is greatly reduced as compared with the related art, and a decrease in yield due to electrostatic breakdown can be prevented.

Third Embodiment FIG. 3 is a schematic diagram showing an electrode structure of an array substrate according to a third embodiment, and is a schematic plan view showing an electrode structure near input / output terminals. FIG. 3 is FIG.
(A), and equivalent parts are denoted by the same reference numerals. Here, differences from the first embodiment will be described.

In the third embodiment, the protective resistive element 13 constituting the protective capacitive element 21 has a planar shape of the input / output terminal 1.
It is formed in a saw-like shape at the end overlapping with 1.

As described above, when the end portion of the protective resistance element 13 is formed in a sawtooth shape, the thickness of the gate insulating film 14 covering the sawtooth portion is partially reduced, and the shape is sharpened. Therefore, the high electric field of the static electricity is concentrated on a particularly sharp portion of the saw-like portion. When the end of the protective resistance element 13 is rectangular as in the first embodiment, there are two corners that are easily broken, but when the end is saw-shaped as shown in FIG. Breakage occurs in the range, the high electric field energy of the static electricity is dispersed, and more energy is consumed at the time of breakdown. Therefore, the function as a protection circuit can be further improved as compared with the first embodiment.

In the third embodiment, the protection circuit provided with the protection resistor element 13 has been described as an example. However, for example, as shown in FIG. 4, the invention can also be applied to a protection circuit provided with the protection diode element 18. In FIG. 4, the protection capacitance element 22
Is formed in a saw-tooth shape at an end overlapping with the input / output terminal 11.
Also in this case, the high electric field energy of the static electricity is further consumed, so that the function as the protection circuit can be further improved.

In the third embodiment, the protection resistance element 13
And an example in which the end portion of the protection diode element 18 is formed in a saw shape, the action of dispersing the high electric field energy of the static electricity and further consuming the energy is not limited to such a saw shape, but a plurality of acute angles. This can be achieved by forming a typical projection.

Fourth Embodiment FIG. 5 is a schematic diagram showing an electrode structure of an array substrate according to a fourth embodiment.
(A) is a schematic plan view showing an electrode structure near an input / output terminal,
FIG. 5B is a schematic cross-sectional view taken along the line cc ′ of FIG.

In the fourth embodiment, an example in which a protection element and a protection capacitance element are formed in parallel will be described. FIG. 5
Here, an example in which a diode element is used as a protection element is shown, and the same reference numerals are given to parts equivalent to those in the second embodiment.

Input / output terminal 1 formed on insulating substrate 10
1 and 12 are electrically connected by a protection diode element 18. This protection diode element 18
The diode element is formed by the same layer as the active layer forming the transistor element and by controlling the amount of doped impurities. However, the protection diode element 18 and the input / output terminal 11 are arranged apart from each other in a plane, and the capacitance element as in the second embodiment is not formed.

In the fourth embodiment, as shown in FIG. 5B, a part of the input / output terminal 11 and the resistance element 2 formed of the same layer as the active layer of the transistor element (not shown) are used.
2 are arranged so as to overlap in a plane with the gate insulating film 23 interposed therebetween. Here, the resistance element 22 and a part of the input / output terminal 11 form a protection capacitance element 24 via the gate insulating film 23. The resistance element 22 is formed of the same layer as the active layer forming the transistor element, and becomes a resistance element by controlling the amount of doped impurities.

An interlayer insulating film 25 is formed on the surfaces of the input / output terminals 11 and the gate insulating film 23, and a wiring 27 of the same layer as the source / drain electrodes of the transistor element (not shown) is formed thereon. The other end of the resistance element 22 has an interlayer insulating film 25 thicker than the gate insulating film 23.
Are arranged so as to overlap the wiring 27 in a plane through the intermediary. Here, the resistance element 22 and the wiring 27 form a capacitance element 28 via an interlayer insulating film 25.

The electrode structure of the fourth embodiment is also formed in the same step as the transistor element (not shown). When the electrode structure is formed, the input / output terminal 11 and the protection diode element 18 are connected by the wiring 17. The protection diode element 18 is electrically connected and functions as a protection element.

A protection diode element 1 as shown in FIG.
8. In a protection circuit composed of the protection capacitance element 24 and the capacitance element 28, if static electricity that destroys the gate electrode is generated before the source / drain electrodes of the transistor element (not shown) are formed, the transistor The protection capacitance element 24 is destroyed before the gate electrode of the element. At this time, since the high electric field energy of the static electricity is consumed, the gate electrode can be prevented from being damaged by the static electricity. When a large current that exceeds the allowable amount of the protection diode element 18 flows at the time when the transistor element is formed and the protection diode element 18 functions as the protection element, the amount exceeding the allowable amount is used. The protection capacitor 24 is destroyed by the current. Also at this time, the high electric field energy of the static electricity is consumed.
Therefore, the probability that the transistor element is destroyed by static electricity can be greatly reduced as compared with the related art.

The capacitance element 28 is formed by the gate insulating film 23
Since the structure is formed with an interlayer insulating film 25 having a larger thickness than that of the protective capacitor 24, the current is captured by the capacitor 28 even if the protective capacitor 24 is broken. And will not flow out to other areas. As described above, a large current exceeding the allowable amount of the protection diode element 18 is consumed and captured by the protection capacitance element 24 and the capacitance element 28.
As compared with the cases of Nos. 1 to 3, it is possible to more effectively prevent the yield from being reduced due to electrostatic breakdown.

In the fourth embodiment, an example is shown in which a diode element is used as a protection element. However, as in the first embodiment, a resistance element may be used as a protection element. Further, the protection capacitance element may be formed in a part of the protection element as in the first and second embodiments, or the protection capacitance element in that case may be shaped as in the third embodiment.

Further, even if a protection resistor element or a protection diode element is not formed as a protection element, it can function effectively against electrostatic breakdown.

Further, in the transistor elements of the first to fourth embodiments, an example in which the active layer is formed of polysilicon has been described. However, the active layer of the transistor element may be formed of amorphous silicon.

In the first to fourth embodiments, the case where the present invention is applied to an array substrate of a liquid crystal display device has been described. However, a circuit element protection circuit according to the present invention is a circuit element such as a transistor element or a wiring pattern on an insulating substrate. The present invention can be generally applied to a semiconductor device having elements formed thereon.

[0048]

As described above, according to the circuit element protection circuit according to the present invention, with regard to static electricity generated in the process of forming the transistor element, the capacitive element is destroyed before the gate electrode is destroyed, Since the high electric field energy of the gate electrode is consumed, the breakdown of the gate electrode can be prevented. Also, if a large current that exceeds the allowable amount of the protection element flows due to static electricity after the transistor element is formed, the capacitive element is destroyed by the current exceeding the allowable amount, and the high electric field energy of the static electricity also increases. Since it is consumed, the probability of destruction of a transistor element near an input / output terminal due to static electricity can be significantly reduced. Therefore, it is possible to prevent a decrease in the yield of the product due to the electrostatic breakdown.

In particular, when a plurality of protrusions are formed at the end of a resistance element or a diode element, destruction can be caused in a wide range of a capacitance element. Energy can be further consumed, and the function as a protection circuit can be further improved.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an electrode structure of an array substrate according to a first embodiment.

FIG. 2 is a schematic diagram showing an electrode structure of an array substrate according to a second embodiment.

FIG. 3 is a schematic diagram showing an electrode structure of an array substrate according to a third embodiment.

FIG. 4 is a schematic diagram showing another electrode structure of the array substrate according to the third embodiment.

FIG. 5 is a schematic diagram showing an electrode structure of an array substrate according to a fourth embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Insulating substrate, 11, 12 ... Input / output terminal, 13 ... Protective resistance element 14, 23 ... Gate insulating film, 15, 19, 21, 22, 22
24: protection capacitance element 18: protection diode element, 28: capacitance element

Claims (4)

[Claims] 1. A protection circuit for a circuit element, comprising a resistor element disposed on a substrate having a circuit element and an input / output terminal connected to the circuit element and connected between adjacent input / output terminals, A protection circuit for a circuit element, wherein an end of the element and a part of the input / output terminal are arranged so as to form a capacitive element via an insulating film. 2. A protection circuit for a circuit element comprising a diode element disposed on a substrate having a circuit element and an input / output terminal connected to the circuit element and connected between the adjacent input / output terminals, A protection circuit for a circuit element, wherein an end of the element and a part of the input / output terminal are arranged so as to form a capacitive element via an insulating film. 3. The protection circuit for a circuit element according to claim 1, wherein a plurality of protrusions are formed at an end of the resistance element or the diode element. 4. A resistive element which is arranged on a substrate having a circuit element and an input / output terminal connected thereto and which is formed of the same layer as an end of the input / output terminal and an active layer of the circuit element. A protection circuit for a circuit element, which is arranged so as to form a capacitor element via an insulating film.