KR102000056B1 - Electrostatic discharge protection circuit and method for fabricating the same - Google Patents

Abstract

The present invention relates to an antistatic circuit composed of a double gate TFT thin film transistor and an organic light emitting diode display device including the same. The antistatic circuit of the present invention includes a first gate electrode formed on a substrate; A gate insulating layer formed on the substrate and including a first gate contact hole exposing a portion of the first gate electrode; A semiconductor layer formed on the gate insulating layer to overlap the first gate electrode; A drain electrode formed on the semiconductor layer and connected to the first gate electrode through the first gate contact hole, and a source electrode spaced apart from the drain electrode; A passivation layer formed on the substrate and including a second gate contact hole exposing a portion of the source electrode; And at least one double gate TFT diode formed on the passivation layer and including a second gate electrode connected to the source electrode through the second gate contact hole, wherein the second gate electrode is connected to an input terminal. The drain electrode is grounded.

Description

Antistatic circuit and method of manufacturing the same {ELECTROSTATIC DISCHARGE PROTECTION CIRCUIT AND METHOD FOR FABRICATING THE SAME}

The present invention relates to an antistatic circuit, and to an antistatic circuit consisting of a double gate TFT diode and a method of manufacturing the same.

Video display devices that implement a variety of information as screens are core technologies of the information and communication era, and are being developed in a direction of thinner, lighter, portable and high performance. Accordingly, various display devices such as a liquid crystal display (LCD), a plasma display panel (PDP), an electro luminescent display (ELD), and the like are utilized, and such display devices include elements for displaying an image. In particular, an antistatic circuit is provided inside the display device to protect the devices from electric shock such as external static electricity.

1 is a diagram illustrating a voltage flow of a display device when a rated voltage and an overvoltage are applied. FIG. 2A is a circuit diagram of a general antistatic circuit, and FIG. 2B is a circuit diagram of FIG. 2A in a diode structure. 3 is a cross-sectional view of a general antistatic circuit including two TFT diodes.

As shown in FIG. 1, when the rated voltage is applied, the rated voltage is applied to an element such as a thin film transistor array (TFT array) provided in the display area to drive the display device. In addition, when an instantaneous overvoltage such as electrostatic discharge (ESD) is applied, the overvoltage is discharged through an ESD protection circuit connected to the ground terminal.

In general, an antistatic circuit is a structure in which 2N (N is an integer of 1 or more) TFT diodes are connected. For example, as shown in Figs. 2A and 2B, when the antistatic circuit is composed of two TFT diodes, the first TFT diode and the second TFT diode are connected in parallel. In the TFT diode as described above, the gate electrode and the drain electrode are connected to each other to drive the diode. At this time, the first TFT diode is driven when positive static electricity flows in, and the second TFT diode is driven when negative static electricity flows in.

Specifically, as shown in FIG. 3, the TFT diode includes the gate electrodes 11a and 11b, the gate insulating layer 12, the semiconductor layers 13a and 13b, the drain electrodes 14a and 14c, and the source electrode formed on the substrate 10. (14b, 14d). At this time, the drain electrodes 14a and 14c of the first TFT diode and the second TFT diode are connected to the gate electrodes 11a and 11b, respectively. The drain electrode 14a of the first TFT diode is connected to the source electrode 14d of the second TFT diode via the first metal pattern 16a.

In this case, the first metal pattern 16a is connected to the gate / data input signal. The source electrode 14d of the first TFT diode is grounded, and the drain electrode 14a of the second TFT diode is also grounded through the second metal pattern 16b formed on the protective film 15.

That is, the antistatic circuit has a structure in which 2N TFT diodes are horizontally connected to each other and occupies a large amount of horizontal area. In particular, in the case of applying the same to a high resolution display device having a narrow wiring gap, it is necessary to reduce the size of the TFT diode. However, when the size of the TFT diode is reduced, the current bypass capability decreases, and when the number of TFT diodes is reduced, the leakage current of the antistatic circuit increases, which causes a problem that the reliability of the display device is degraded.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and by providing a double gate TFT diode, to provide an antistatic circuit and a method of manufacturing the same, the horizontal area is minimized and the efficiency is improved.

An antistatic circuit of the present invention for achieving the above object comprises a first gate electrode formed on a substrate; A gate insulating layer formed on the substrate and including a first gate contact hole exposing a portion of the first gate electrode; A semiconductor layer formed on the gate insulating layer to overlap the first gate electrode; A drain electrode formed on the semiconductor layer and connected to the first gate electrode through the first gate contact hole, and a source electrode spaced apart from the drain electrode; A passivation layer formed on the substrate and including a second gate contact hole exposing a portion of the source electrode; And at least one double gate TFT diode formed on the passivation layer and including a second gate electrode connected to the source electrode through the second gate contact hole, wherein the second gate electrode is connected to an input terminal. The drain electrode is grounded.

In addition, the method of manufacturing an antistatic circuit of the present invention for achieving the same object relates to a method of manufacturing an antistatic circuit comprising at least one or more double gate TFT diode, the step of forming the double gate TFT diode, the substrate Forming a first gate electrode on the substrate; Forming a gate insulating layer including a first gate contact hole exposing a portion of the first gate electrode on the substrate; Forming a semiconductor layer on the gate insulating layer to overlap the first gate electrode; Forming a drain electrode connected to the first gate electrode through the first gate contact hole and a source electrode spaced apart from the drain electrode on the semiconductor layer; Forming a passivation layer on the substrate, the passivation layer including a second gate contact hole exposing a portion of the source electrode; And forming a second gate electrode connected to the source electrode through the second gate contact hole on the passivation layer, wherein the second gate electrode is connected to an input terminal and the drain electrode is grounded.

The drain electrode of the first double gate TFT diode in which the second gate electrode of the double gate TFT diode is connected to the input terminal is connected to the source electrode of the second double gate TFT diode adjacent to the first double gate TFT diode. The drain electrode of the second double gate TFT diode is grounded.

The semiconductor layer is formed of a material selected from oxides, organic materials, amorphous silicon, and polycrystalline silicon.

The protective film and the gate insulating film are formed of the same material, and the protective film and the gate insulating film have the same thickness.

The first gate electrode and the second gate electrode may be formed of a transparent conductive material or an opaque conductive material, or may have a structure in which the transparent conductive material and the opaque conductive material are stacked.

As described above, the antistatic circuit of the present invention and a method of manufacturing the same include one or more double gate TFT diodes. Since the double gate TFT diode can be driven in the positive direction, one double gate TFT diode can emit both positive and negative static electricity to the outside. Thus, by reducing the number of TFT diodes, it is possible to reduce the horizontal area of the antistatic circuit, and to prevent the parasitic capacitance from increasing by the antistatic circuit.

1 is a diagram illustrating a voltage flow of a display device when a rated voltage and an overvoltage are applied.
2A is a circuit diagram of a general antistatic circuit.
FIG. 2B is a circuit diagram of FIG. 2A in a diode structure.
3 is a cross-sectional view of a general antistatic circuit including two TFT diodes.
4A is a plan view of an antistatic circuit of the present invention.
4B is a cross-sectional view taken along the line II ′ of FIG. 4A.
5 is a plan view of an antistatic circuit according to another embodiment of the present invention.
6 is a circuit diagram of an antistatic circuit of the present invention.
7A is a circuit diagram showing two double gate TFT diodes connected.
FIG. 7B is a cross-sectional view of FIG. 7A.
8A to 8F are sectional views showing the manufacturing method of the antistatic circuit of the present invention.

The antistatic circuit of the present invention comprises at least one double gate TFT diode. In this case, the antistatic circuit is formed in a structure connected to a gate wiring, a data wiring, and the like for applying a signal for driving the thin film transistor array unit of the display device.

Hereinafter, with reference to the accompanying drawings will be described in detail the antistatic circuit of the present invention and a manufacturing method thereof.

4A is a plan view of the antistatic circuit of the present invention, and FIG. 4B is a sectional view taken along line II ′ of FIG. 4A. 5 is a plan view of an antistatic circuit according to another embodiment of the present invention.

4A and 4B, the antistatic circuit of the present invention includes at least one double gate TFT diode. The double gate TFT diode includes a first gate electrode 105, a gate insulating layer 110, a semiconductor layer 115, a drain electrode 120a, a source electrode 120b, and a second gate electrode 130. In this case, the double gate TFT diode is a thin film transistor selected from an oxide thin film transistor, an organic thin film transistor, an amorphous silicon thin film transistor, and a polysilicon thin film transistor.

Specifically, the first gate electrode 105 is formed on the substrate 100. The first gate electrode 105 may be formed of a transparent conductive material or an opaque conductive material, or may have a structure in which a transparent conductive material and an opaque conductive material are stacked. The transparent conductive material is selected from tin oxide (TO), indium tin oxide (ITO), indium zinc oxide (IZO), and indium tin zinc oxide (ITZO). . The non-transparent conductive material may be copper (Cu), silver (Ag), aluminum (Al), chromium (Cr), molybdenum (Mo), tungsten (W), titanium (Ti), thallium (Ta) and alloys thereof And the like.

The gate insulating layer 110 is formed of an inorganic insulating material such as SiOx, SiNx, Al ₂ O _3, or the like on the substrate 100 to cover the first gate electrode 105. The semiconductor layer 115 is formed on the gate insulating layer 110 to overlap the first gate electrode 105. The semiconductor layer 115 is formed of an oxide, an organic material, amorphous silicon, polycrystalline silicon, or the like.

The drain electrode 120a and the source electrode 120b having a structure spaced apart from each other are formed on the semiconductor layer 115. The drain electrode 120a is connected to the first gate electrode 105 through a first gate contact hole formed in the gate insulating layer 110 to expose the first gate electrode 105. In this case, as shown in FIG. 5, the drain electrode 120a and the source electrode 120b have a plurality of protrusions formed at one side thereof, and the protrusions of the drain electrode 120a and the source electrode 120b have a plurality of protrusions. The shapes of the drain electrode 120a and the source electrode 120b may be variously changed.

The passivation layer 125 is formed on the substrate 100 to cover the drain electrode 120a and the source electrode 120b. The passivation layer 125 may be formed of an inorganic insulating material such as SiOx, SiNx, Al ₂ O ₃ , or an organic insulating material such as acrylic, polyimide (PI), polyamide (PA), and benzocyclobutene (BCB). have. In particular, the passivation layer 125 is formed to have the same thickness as the gate insulating layer 110, and preferably formed of the same material as the gate insulating layer 110.

The second gate electrode 130 is formed on the passivation layer 125. Like the first gate electrode 105, the second gate electrode 130 may be formed of a transparent conductive material or an opaque conductive material, or may have a structure in which the transparent conductive material and the non-transparent conductive material are stacked. The second gate electrode 130 as described above is connected to the source electrode 120b through a second gate contact hole formed in the passivation layer 125 to expose the source electrode 120b. In this case, the second gate electrode 130 is formed of the same material as the pixel electrode of the thin film transistor array formed in the display area.

The TFT diode of the present invention as described above has a double gate structure including the first gate electrode 105 and the second gate electrode 130. Specifically, the second gate electrode 130 of the double gate TFT diode is connected to the input terminal, and the drain electrode 120a is grounded. At this time, a gate / data input signal is input to the input terminal, and the double gate TFT diode is connected to each drive wiring such as a gate wiring and a data wiring. When the voltage applied to the gate wiring, the data wiring, or the like is not suitable for driving the thin film transistor array, it is emitted to the outside.

As described above, in the antistatic circuit of the present invention, the first gate electrode 105 is connected to the drain electrode 120a, and the second gate electrode 130 is at least one or more double gates connected to the source electrode 120b. It consists of a TFT diode. In particular, the antistatic circuit of the present invention can emit not only positive static electricity but also negative static electricity to the outside with only one double gate TFT diode.

For example, when positive static electricity flows into the double gate TFT diode through an input terminal through which a gate / data input signal is input, the positive static electricity passes through the second gate electrode 130 and the source electrode ( In the direction of the drain electrode 120a at 120b. On the contrary, when negative static electricity flows through the input terminal, negative static electricity is discharged from the drain electrode 120a to the source electrode 120b through the first gate electrode 105.

A general antistatic circuit is composed of a TFT diode in which current is conducted only in one direction, and thus, at least two TFT diodes are provided to emit positive and negative static electricity to the outside. In particular, since the plurality of TFT diodes are arranged side by side horizontally, the size of the antistatic circuit is increased. In addition, as the number of TFT diodes increases, the reaction rate of the antistatic circuit decreases, and thus, the reaction cannot be reacted to an instantaneous electrostatic discharge.

However, the antistatic circuit of the present invention, as described above, includes a double gate TFT diode in which current is conducted in both directions. At this time, one double gate TFT diode is equivalent to two vertical TFT diodes arranged horizontally.

6 is a circuit diagram of an antistatic circuit of the present invention.

As illustrated in FIG. 6, the antistatic circuit of the present invention may emit positive and negative static electricity to the outside using one double gate TFT diode. Thus, the number of TFT diodes is reduced by one half compared to a general antistatic circuit, and has a high performance antistatic capability relative to area.

In addition, as the number of TFT diodes is reduced, the parasitic capacitance can be prevented from increasing by the antistatic circuit. Further, when the antistatic circuit of the present invention is applied to an organic light emitting diode display device having a panel (GIP) structure as a gate IC, the layout can be easily designed.

In particular, the antistatic circuit of the present invention may comprise a plurality of double gate TFT diodes.

FIG. 7A is a circuit diagram showing two double gate TFT diodes connected, and FIG. 7B is a cross-sectional view of FIG. 7A showing a first double gate TFT diode and a second double gate TFT diode.

As shown in FIGS. 7A and 7B, an antistatic circuit including two double gate TFT diodes has a structure in which a first double gate TFT diode and a second double gate TFT diode are connected side by side. The two double gate TFT diodes perform the same function as four conventional TFT diodes, but have a size 1/2 of the typical four TFT diodes.

Specifically, the second gate electrode 230a of the first double gate TFT diode is connected to the gate / data input signal, and the drain electrode 220c of the second double gate TFT diode is grounded. The source electrode 220d of the second double gate TFT diode is connected to the drain electrode 220a of the first double gate TFT diode. At this time, the source electrode 220d of the second double gate TFT diode and the drain electrode 220a of the first double gate TFT diode are connected to the second gate electrode 230b connected to the source electrode 220d of the second double gate TFT diode. Are connected to each other through.

For example, when positive static electricity flows into the antistatic circuit through the input terminal, positive static electricity is discharged from the first double gate TFT diode toward the second double gate TFT diode. Conversely, when negative static electricity flows through the input terminal, negative static electricity is discharged from the second double gate TFT diode toward the first double gate TFT diode.

Hereinafter, the manufacturing method of the antistatic circuit of the present invention will be described in detail.

8A to 8F are cross-sectional views illustrating a method of manufacturing the antistatic circuit of the present invention.

As shown in FIG. 8A, the gate electrode 105 is formed on the substrate 100. The gate electrode 105 is formed of the same material as the gate electrode of the thin film transistor formed in the display area of the substrate, and is formed of a transparent conductive material or an opaque conductive material, or a structure in which a transparent conductive material and an opaque conductive material are stacked. It can be formed as. The gate insulating layer 110 is formed on the substrate 100 to cover the gate electrode 105. In this case, the gate insulating layer 110 is formed of an inorganic insulating material such as SiOx, SiNx, Al ₂ O _3, or the like.

Subsequently, as shown in FIG. 8B, the semiconductor layer 115 is formed on the gate insulating layer 110 to overlap the gate electrode 105. The semiconductor layer 115 is formed of an oxide, an organic material, amorphous silicon, polycrystalline silicon, or the like.

8C, the gate insulating layer 110 is selectively removed to expose the first gate electrode 105 to form the first gate contact hole 110H. The process of forming the first gate contact hole 110H may be performed before the semiconductor layer 115 is formed.

As shown in FIG. 8D, the drain electrode 120a and the source electrode 120b having the structure spaced apart from each other are formed on the semiconductor layer 115. The drain electrode 120a is connected to the first gate electrode 105 through the first gate contact hole 110H. Next, as shown in FIG. 8E, the passivation layer 125 is formed on the substrate 100 to cover the drain electrode 120a and the source electrode 120b. The passivation layer 125 may be formed of an inorganic insulating material such as SiOx, SiNx, Al ₂ O ₃ , or an organic insulating material such as acrylic, polyimide (PI), polyamide (PA), and benzocyclobutene (BCB). have. In addition, the passivation layer 125 may have a structure in which an inorganic insulating material and an organic insulating material are stacked.

In particular, the protective film 125 may be formed to have the same thickness as the gate insulating film 110. This is to equalize the gap between the semiconductor layer 115 and the first gate electrode 105 and the gap between the semiconductor layer 115 and the second gate electrode 130 to be described later. In addition, the passivation layer 125 and the gate insulating layer 110 may be formed of the same material so that the double gate TFT diode may have a vertically symmetrical structure.

Next, the protective layer 125 is selectively removed to form a second gate contact hole 125H exposing the source electrode 120b. The process of forming the second gate contact hole 125H is performed simultaneously with the process of forming a drain contact hole for connecting the thin film transistor formed in the display area and the pixel electrode. Accordingly, the second gate contact hole 125H for connecting the source electrode 120b and the second gate electrode 130 to be described later may be formed without an additional mask process.

Next, as shown in FIG. 8F, the second gate electrode 130 is formed on the passivation layer 125. In this case, the second gate electrode 130 is formed simultaneously with the pixel electrode of the thin film transistor array formed in the display area. The second gate electrode 130 is connected to the source electrode 120b through the second gate contact hole 125H. Like the first gate electrode 105, the second gate electrode 130 may be formed of a transparent conductive material or an opaque conductive material, or may have a structure in which the transparent conductive material and the non-transparent conductive material are stacked.

The TFT diode of the antistatic circuit of the present invention as described above includes a double gate TFT diode including first and second gate electrodes 105 and 130 overlapping each other with the semiconductor layer 115 interposed therebetween. Thus, by reducing the number of TFT diodes, it is possible to reduce the size of the antistatic circuit. The parasitic capacitance can be prevented from increasing by the antistatic circuit.

On the other hand, the present invention described above is not limited to the above-described embodiment and the accompanying drawings, it is possible that various substitutions, modifications and changes within the scope without departing from the technical spirit of the present invention It will be apparent to those of ordinary skill in Esau.

100, 200: substrate 105, 205a, 205b: first gate electrode
110 and 210: gate insulating film 110H: first gate contact hole
115, 215a, 215b: semiconductor layers 120a, 220a, 220c: drain electrodes
120b, 220b, 220d: source electrodes 125, 225: protective film
125H: second gate contact hole 130, 230a, 230b: second gate electrode

Claims (10)

A first gate electrode formed on the substrate;
A gate insulating layer formed on the substrate and including a first gate contact hole exposing a portion of the first gate electrode;
A semiconductor layer formed on the gate insulating layer to overlap the first gate electrode;
A drain electrode formed on the semiconductor layer and connected to the first gate electrode through the first gate contact hole, and a source electrode spaced apart from the drain electrode;
A passivation layer formed on the substrate and including a second gate contact hole exposing a portion of the source electrode; And
At least one double gate TFT diode formed on the passivation layer and including a second gate electrode connected to the source electrode through the second gate contact hole;
And the second gate electrode is connected to an input terminal and the drain electrode is grounded. The method of claim 1,
The drain electrode of the first double gate TFT diode in which the second gate electrode of the double gate TFT diode is connected to the input terminal is connected to the source electrode of the second double gate TFT diode adjacent to the first double gate TFT diode. The drain electrode of the second double gate TFT diode is grounded. The method of claim 1,
The semiconductor layer is an antistatic circuit, characterized in that formed of a material selected from oxide, organic material, amorphous silicon and polycrystalline silicon. The method of claim 1,
And the protective film and the gate insulating film are formed of the same material, and the protective film and the gate insulating film have the same thickness. The method of claim 1,
And the first gate electrode and the second gate electrode are formed of a transparent conductive material or an opaque conductive material, or a structure in which the transparent conductive material and the opaque conductive material are laminated. A method of manufacturing an antistatic circuit comprising at least one or more double gate TFT diodes,
Forming the double gate TFT diode,
Forming a first gate electrode on the substrate;
Forming a gate insulating layer including a first gate contact hole exposing a portion of the first gate electrode on the substrate;
Forming a semiconductor layer on the gate insulating layer to overlap the first gate electrode;
Forming a drain electrode connected to the first gate electrode through the first gate contact hole and a source electrode spaced apart from the drain electrode on the semiconductor layer;
Forming a passivation layer on the substrate, the passivation layer including a second gate contact hole exposing a portion of the source electrode; And
Forming a second gate electrode on the passivation layer, the second gate electrode being connected to the source electrode through the second gate contact hole;
And the second gate electrode is connected to an input terminal and the drain electrode is grounded. The method of claim 6,
The drain electrode of the first double gate TFT diode in which the second gate electrode of the double gate TFT diode is connected to the input terminal is connected to the source electrode of the second double gate TFT diode adjacent to the first double gate TFT diode. The drain electrode of the second double gate TFT diode is grounded. The method of claim 6,
The semiconductor layer is a method of manufacturing an antistatic circuit, characterized in that formed of a material selected from oxide, organic material, amorphous silicon and polycrystalline silicon. The method of claim 6,
And the protective film and the gate insulating film are formed of the same material, and the protective film and the gate insulating film have the same thickness. The method of claim 6,
And the first gate electrode and the second gate electrode are formed of a transparent conductive material or an opaque conductive material, or a structure in which the transparent conductive material and the non-transparent conductive material are laminated.

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