JP2002190390A - Repair method and manufacturing method for light- emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for repairing a light-emitting device with which images of high quality are displayed, even if a pin hole is formed when an EL layer is film-formed. SOLUTION: When a reverse bias voltage is applied to an EL element with time intervals, almost no current flows to an EL layer but flows to a defective part which is shorted. If a large current flows to the defective part, the temperature at the part rises to burn the part, gasificate for evaporation, oxidate, or carbonize to turn into an insulating body, causing changes at the defective part. As a result, a current flowing to the EL element, when a voltage of reverse bias is applied becomes small.

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for repairing an EL panel in which an EL element formed on a substrate is sealed between the substrate and a cover material, and a method for manufacturing using the repair method. The invention also relates to a method for repairing an EL module having an IC mounted on the EL panel. In this specification, the EL panel and the EL module are collectively referred to as a light emitting device.

[0001]

2. Description of the Related Art An EL element emits light by itself and therefore has high visibility, is not required to have a backlight required for a liquid crystal display (LCD), is optimal for thinning, and has no restriction on a viewing angle. Therefore, in recent years, light emitting devices using EL
It is attracting attention as an electro-optical device replacing T and LCD.

An EL element has a layer containing an organic compound capable of obtaining luminescence (Electro Luminescence) generated by applying an electric field (hereinafter, referred to as an EL layer), an anode layer, and a cathode layer. Luminescence in an organic compound includes light emission (fluorescence) when returning from a singlet excited state to a ground state and light emission (phosphorescence) when returning to a ground state from a triplet excited state. The present invention can be applied to a light emitting device using either light emission.

[0003] In this specification, all layers provided between an anode and a cathode are defined as EL layers. Specifically, the EL layer includes a light emitting layer, a hole injection layer, an electron injection layer, a hole transport layer,
An electron transport layer and the like are included. Basically, the EL element has an anode /
It has a structure in which a light emitting layer / cathode is laminated in order. In addition to this structure, an anode / hole injection layer / light emitting layer / cathode or anode / hole injection layer / light emitting layer / electron transport layer / cathode Etc. in some cases.

[0004] In this specification, emission of an EL element is referred to as driving of the EL element. In this specification, a light-emitting element including an anode, an EL layer, and a cathode is referred to as an EL element.

[0005]

Generally, an EL element is
After one of the anode and the cathode is formed, an EL layer is formed so as to be in contact with the electrode, and the other of the anode and the cathode is formed so as to be in contact with the EL layer.

[0006] As a method of forming an EL layer, there are mainly a film forming method by vapor deposition and a film forming method by spin coating. In any of the methods, when the electrodes and the EL layer are formed, the substrate is washed before the film is formed and the cleanliness in a clean room where the film is formed is controlled so that dust and the like do not adhere to the substrate. Efforts are being made to ensure thoroughness.

However, in spite of the above efforts, there is a case where dust or the like adheres to the electrodes and the like, and a hole (pinhole) is formed in the formed EL layer. FIG. 12A shows two electrodes 20.
FIG. 1 schematically shows a cross-sectional view of the EL element 200 when the elements 1 and 202 are short-circuited. When a pinhole opens in the EL layer 203,
When the electrode 202 is formed on the EL layer 203, the two electrodes 201 and 202 may be connected at a pinhole and short-circuited. Hereinafter, a portion where two layers formed with the light emitting layer interposed therebetween is in contact with a pinhole formed in the light emitting layer is referred to as a defective portion 204.

FIG. 13A shows a voltage-current characteristic of an EL element having no defective portion, and FIG. 13B shows a voltage-current characteristic of an EL element short-circuited at the defective portion.

Comparing FIG. 13A and FIG. 13B, the current flowing in the EL element 200 when a reverse bias voltage is applied to the EL element 200 is larger in the case of FIG. 13B.

[0010] This is different from FIG.
In the case (B), the two electrodes are short-circuited in the defective portion 204, so that a current flows in the defective portion 204.

At the defect 204, two electrodes 201,
When the short circuit 202 occurs, the emission luminance of the EL layer decreases. FIG. 12B schematically shows a current flow when a forward bias voltage is applied to an EL element having a defective portion.

At the defective portion 204, two electrodes 201,
When the short circuit 202 is present, the defective portion 204 has a resistance R
It is considered that the electrode has _SC and connects two electrodes of the EL element 200. Therefore, when a forward current I _ori flows from one electrode of the EL element, the current flowing to the defective portion 204 is I _SC , and the current flowing to the EL layer 203 is I _{di o}
Then, the current I _ori = I _SC + I _dio is satisfied.

Assuming that I _ori is constant in the above-mentioned formula I _ori = I _SC + I _dio , the current I _dio that actually flows through the EL layer 203 becomes small in an EL element having a defective portion. When the resistance R _SC in the defective portion 204 decreases, I _SC increases, so that this tendency becomes remarkable, and the rectifying property of the EL element 200 further deteriorates.

When the current I _dio flowing through the EL layer 203 decreases, the light emission luminance of the EL element 200 decreases. That is, when a short circuit occurs at the defective portion, the emission luminance of the EL element when a forward bias voltage is applied is lower than when the short circuit does not occur.

[0015] Even when the EL layer is formed by laminating a plurality of layers, if a pinhole is formed in the light emitting layer, a hole injection layer or a hole transport layer is formed through the pinhole. Then, the electron injection layer or the electron transport layer is connected. A portion where the hole injection layer or the hole transport layer is connected to the electron injection layer or the electron transport layer is also in a state where a reverse bias current flows like the defective portion where the electrode is short-circuited. This causes a decrease in light emission luminance of the EL element. Hereinafter, all portions where the two layers formed with the light emitting layer interposed therebetween are in contact via pinholes formed in the light emitting layer are collectively referred to as a defective portion.

Furthermore, in addition to a decrease in the emission luminance of the EL element, if a short circuit occurs at a defective portion, a current always flows through the defective portion, so that the deterioration of the EL layer around the defective portion is promoted. .

The present invention has been made in view of the above problems, and has as its object to devise a method for repairing a defective portion.

[0018]

Means for Solving the Problems Even if a defect is formed in an EL element, if the resistance at the defect is increased, the present inventors can improve the EL when a forward bias voltage is applied.
We thought that it would be possible to prevent the current flowing through the layer from being reduced.

Therefore, a method has been devised in which a reverse bias voltage is applied to the EL element and a reverse bias current I _rev is supplied to increase the resistance R _SC at the defective portion.

When a reverse bias current I _rev is applied to the EL element, most of the current I _rev does not flow to the EL layer but to the short-circuited defective portion. If the current flowing through the defective part is large, the temperature of the defective part rises,
Some change occurs in the defective portion due to evaporation and evaporation, or oxidation or carbonization to become an insulator, resulting in an increase in the resistance R _SC . Note that, in this specification, a defective portion whose resistance R _SC is increased by flowing a reverse bias current is referred to as a denatured layer.

When the resistance R _SC is increased, when a forward bias voltage is applied to the EL element, the current flowing through the denatured layer is reduced, and the current flowing through the EL layer is increased instead, and the light emission luminance is increased.

Further, since a current always flows in the defective portion, deterioration of the EL layer existing around the defective portion is easily promoted. However, since the denatured layer has a high resistance R _SC , it is difficult for a current to flow, thereby preventing the deterioration of the EL layer around the denatured layer from being promoted.

The repair method of the present invention can be used not only for an active matrix type light emitting device but also for a passive type light emitting device.

The configuration of the present invention will be described below.

According to the present invention, there is provided a method of repairing a light emitting device in which a first voltage and a second voltage are sequentially applied to an EL element, wherein the first voltage and the second voltage have different heights. A method for repairing a light emitting device, wherein the voltage is a reverse bias voltage is provided.

According to the present invention, there is provided a method of repairing a light emitting device in which a voltage applied to an EL element is gradually changed from a first voltage to a second voltage, the method comprising repairing the first voltage and the second voltage.
Are provided with reverse bias voltages having different heights from each other.

According to the present invention, there is provided a method of repairing a light emitting device including an EL element having an anode, an EL layer in contact with the anode, and a cathode in contact with the EL layer, wherein a first electrode is provided between the anode and the cathode. And a second voltage are applied in order, and the first voltage and the second voltage are reverse bias voltages having different heights from each other. .

According to the present invention, there is provided a method for repairing a light emitting device including an EL element having an anode, an EL layer in contact with the anode, and a cathode in contact with the EL layer, wherein a voltage is applied between the anode and the cathode. The voltage is gradually changed from a first voltage to a second voltage, and the first voltage and the second voltage are reverse bias voltages having different heights from each other. A repair method is provided.

According to the present invention, there is provided a method for repairing a light emitting device including an EL element having an anode, an EL layer in contact with the anode, and a cathode in contact with the EL layer, wherein a first electrode is provided between the anode and the cathode. The voltage and the second voltage are sequentially applied to insulate or increase the resistance of a portion where a reverse bias current flows between the anode and the cathode, and the first voltage and the second voltage are: There is provided a method for repairing a light emitting device, wherein the voltages are reverse bias voltages having different heights.

According to the present invention, there is provided a method for repairing a light emitting device including an EL element having an anode, an EL layer in contact with the anode, and a cathode in contact with the EL layer, wherein a voltage is applied between the anode and the cathode. By gradually changing the voltage from the first voltage to the second voltage, a portion where a reverse bias current flows between the anode and the cathode is insulated or made to have a high resistance, and the first voltage and the first The method of repairing a light emitting device, wherein the second voltage is a reverse bias voltage having different heights from each other.

The present invention may be characterized in that the first voltage and the second voltage fall within ± 15% of the avalanche voltage of the EL element.

According to the present invention, there is provided a method for repairing a light emitting device in which a first voltage and a second voltage are sequentially applied to an EL element, wherein the first voltage is a ground voltage and the second voltage is a ground voltage.
Is a reverse bias voltage, and a method for repairing the light emitting device is provided.

According to the present invention, there is provided a method of repairing a light emitting device in which a voltage applied to an EL element is gradually changed from a first voltage to a second voltage, wherein the first voltage and the second voltage are different from each other. , One being a ground voltage and the other being a reverse bias voltage.

According to the present invention, there is provided a method for repairing a light emitting device including an EL element having an anode, an EL layer in contact with the anode, and a cathode in contact with the EL layer, wherein a first electrode is provided between the anode and the cathode. And a second voltage are sequentially applied, wherein the first voltage is a ground voltage, and the second voltage is a reverse bias voltage. .

According to the present invention, there is provided a method of repairing a light-emitting device including an EL element having an anode, an EL layer in contact with the anode, and a cathode in contact with the EL layer, wherein a voltage is applied between the anode and the cathode. The voltage is gradually changed from a first voltage to a second voltage, wherein one of the first voltage and the second voltage is a ground voltage and the other is a reverse bias voltage. The repair method of the light emitting device described above is provided.

According to the present invention, there is provided a method for repairing a light emitting device including an EL element having an anode, an EL layer in contact with the anode, and a cathode in contact with the EL layer, wherein a first electrode is provided between the anode and the cathode. The voltage and the second voltage are applied in order to insulate or increase the resistance of the portion where the reverse bias current flows between the anode and the cathode, and the first voltage is a ground voltage, A method for repairing a light emitting device is provided, wherein the second voltage is a reverse bias voltage.

According to the present invention, there is provided a method of repairing a light-emitting device including an EL element having an anode, an EL layer in contact with the anode, and a cathode in contact with the EL layer, wherein a voltage is applied between the anode and the cathode. By gradually changing the voltage from the first voltage to the second voltage, a portion where a reverse bias current flows between the anode and the cathode is insulated or made to have a high resistance, and the first voltage and the voltage One of the second voltages is a ground voltage, and the other is a reverse bias voltage.

The present invention may be characterized in that the reverse bias voltage falls within ± 15% of the avalanche voltage of the EL element.

[0039]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A repair method according to the present invention will be described with reference to FIG. FIG. 1A shows a current flow when a reverse bias voltage is applied to an EL element having a defective portion.
It is the figure which showed typically.

The ground voltage GND and the reverse bias voltage V _rev are alternately applied to the EL element. In FIG. 1 (B),
5 shows a timing chart when a ground voltage GND and a reverse bias voltage V _rev are alternately applied. In the present embodiment, the ground voltage GND and the reverse bias voltage V _rev are alternately applied, but the present invention is not limited to this configuration. In the present invention, a reverse bias voltage may be applied to the EL element. Therefore, a reverse bias voltage V _rev and a reverse bias voltage other than the forward bias voltage or V _rev may be applied to the EL element alternately.

Also, in this embodiment, the EL
A reverse bias voltage is applied to the device, but the present invention is not limited to this. A DC reverse bias voltage may be applied to the EL element.

In this embodiment, the reverse bias voltage is gradually increased until the avalanche phenomenon occurs and the avalanche current flows through the EL element. In this specification, a voltage at which an avalanche current starts flowing through an EL element is referred to as an avalanche voltage.
However, the present invention is not limited to this configuration, and the level of the voltage applied to the EL element can be appropriately set by a designer. The voltage applied to the EL element needs only to be high enough to denature the defective portion and high enough not to break the EL element or to deteriorate the EL layer.

Further, a configuration may be employed in which the reverse bias voltage applied by direct current is gradually increased.

Further, a reverse bias voltage having a constant height may be applied to the EL element at regular intervals, or may be applied as a direct current.

When a reverse bias voltage is applied to the EL element at regular intervals, it is possible to prevent the EL layer around the defective portion from being deteriorated by heat or the like generated by application of the reverse bias voltage. .

Further, by gradually increasing the reverse bias voltage, it becomes easy to find the optimum reverse bias voltage which is optimal for the EL element to be repaired.

The reverse bias voltage V is applied to the EL element._revIs applied
Then, the reverse bias current I_revFlows
You. Reverse bias current I_revFlows into the EL layer 103
Current I _dioAnd the current flowing through the defective portion 104 is I_SCTo be
And I_rev= I_dio+ I_SCMeet. But reverse bias
Since almost no current flows through the EL layer,_rev≒
I_{S C}Holds.

When the current I _rev flows through the defective portion 104, the temperature of the defective portion 104 rises, so that the defective portion is burned out, vaporized and evaporated, or oxidized or carbonized to become an insulator. Thus, it becomes a denatured layer. Therefore, the resistance R _SC increases.

FIG. 2A shows a change in voltage-current characteristics of an EL element having a defective portion 104 over time when the repair method of the present invention is used. The graph of the voltage-current characteristic changes in the direction of the arrow over time. V _av means an avalanche voltage. When a reverse bias voltage is applied, the resistance R _SC of the defective portion increases over time, and the current I _SC flowing through the defective portion accordingly increases.
Is reduced, the current flowing through the EL element is reduced.

FIG. 2B schematically shows a current flow when a forward bias voltage is applied to the EL element. When the current I _SC flowing through the defective portion becomes small, when a forward bias voltage is applied to the EL element, the current I _SC actually flowing through the EL layer
_{The dio} increases, and the emission luminance increases.

By using the method of the present invention, the EL
Pinholes are formed by the influence of dust and the like during layer formation,
Even if two layers formed with the light emitting layer interposed therebetween are short-circuited, the short-circuited defective portion can be changed to a denatured layer to increase the resistance, and a forward bias voltage is applied to the EL element. Thus, the current actually flowing through the EL layer can be increased. Therefore, according to the repair method of the present invention, even when a defective portion exists, the light emission luminance when the same voltage is applied can be increased.

Further, since current always flows in the defective portion, deterioration of the EL layer existing around the defective portion is easily promoted. However, since the denatured layer has a high resistance R _SC , it is difficult for a current to flow, thereby preventing the deterioration of the EL layer around the denatured layer from being promoted.

[0053]

Embodiments of the present invention will be described below.

Embodiment 1 In this embodiment, an example in which the repair method of the present invention is used for an active matrix light emitting device having two thin film transistors (TFTs) in each pixel will be described.

FIG. 3 shows a circuit diagram of a pixel of a light emitting device using the repair method of the present invention. Each pixel has a source signal line Si (i
Is any one of 1 to x) and a power supply line Vi (i is 1
To x) and a gate signal line Gj (j is 1 to
y).

Each pixel is provided with a switching TFT 3
01, an EL driving TFT 302, and an EL element 303
And a capacitor 304.

The gate electrode of the switching TFT 301 is connected to the gate signal line Gj. One of the source region and the drain region of the switching TFT 301 is connected to the source signal line Si, and the other is connected to the EL driving TFT 3.
02 is connected to the gate electrode 02.

The source region of the EL driving TFT 302 is connected to the power supply line Vi, and the drain region is connected to one of the two electrodes of the EL element 303. Of the two electrodes of the EL element 303, E
The part of the L driving TFT 302 not connected to the drain region is connected to the opposite power supply 307.

Note that, of the two electrodes of the EL element 303, the electrode connected to the drain region of the EL driving TFT 302 is called a pixel electrode, and the electrode connected to the counter power supply 307 is called a counter electrode.

The capacitor 304 is provided with an EL driving TF
It is formed between the gate electrode of T302 and the power supply line Vi.

FIG. 4A shows a pixel portion of a light emitting device having a plurality of pixels shown in FIG. The pixel portion 306 has source signal lines S1 to Sx, power supply lines V1 to Vx, and gate signal lines G1 to Gy. In the pixel portion 306, a plurality of pixels 305 are formed in a matrix.

FIG. 4B shows the operation of the TFT in each pixel and the level of the voltage input to the power supply line Vi and the counter electrode when the defective portion of the EL element 303 is repaired. E
When repairing the defective portion of the L element 303, both the switching TFT 301 and the EL driving TFT 302 of each pixel are turned on. Then, by making the voltage of the power supply line Vi constant and changing the voltage of the counter electrode at regular intervals, a predetermined reverse bias current is passed through the EL element at regular intervals.

The repair of the defect of the EL element is performed by the
6 may be performed simultaneously for all the pixels 305 included in the pixel 6, or may be performed for each line or each pixel.

By using the method of the present invention, the EL
Pinholes are formed by the influence of dust and the like during layer formation,
Even if two layers formed with the light emitting layer interposed therebetween are short-circuited, by changing the short-circuited defective portion to a denatured layer and increasing the resistance, when a forward bias voltage is applied to the EL element, The current actually flowing to the EL layer can be increased. Therefore, according to the repair method of the present invention, even when a defective portion exists, the light emission luminance when the same voltage is applied can be increased.

Further, since current always flows in the defective portion, deterioration of the EL layer around the defective portion is easily promoted. However, since the denatured layer has a high resistance R _SC , it is difficult for a current to flow, thereby preventing the deterioration of the EL layer around the denatured layer from being promoted.

Note that the repair method of the present invention is not necessarily applicable only to the light emitting device having the above configuration. The present invention can be used for a light emitting device having any structure.

Embodiment 2 In this embodiment, an example in which the repair method of the present invention is used for an active matrix light emitting device having three thin film transistors (TFTs) in each pixel will be described.

FIG. 5 shows a circuit diagram of a pixel of a light emitting device using the repair method of the present invention. Each pixel has a source signal line Si (i
Is any one of 1 to x) and a power supply line Vi (i is 1
To x) and the write gate signal line Ga
j (j is any one of 1 to y) and an erasing gate signal line Gej (j is any one of 1 to y).

Each pixel is provided with a switching TFT 5
01a, an erasing TFT 501b, and an EL driving TFT
502, an EL element 503, and a capacitor 504.

The gate electrode of the switching TFT 501a is connected to the write gate signal line Gaj.
One of a source region and a drain region of the switching TFT 501a is connected to the source signal line Si, and the other is connected to the source signal line Si.
It is connected to the gate electrode of the L driving TFT 502.

The gate electrode of the erasing TFT 501b is connected to the erasing gate signal line Gej. T for erasing
One of the source region and the drain region of the FT 501b is connected to the power supply line Vi, and the other is connected to the gate electrode of the EL driving TFT 502.

The source region of the EL driving TFT 502 is connected to the power supply line Vi, and the drain region is connected to one of the two electrodes of the EL element 503. Of the two electrodes of the EL element 503, E
The other side of the L driving TFT 502 that is not connected to the drain region is connected to the opposite power supply 507.

Note that, of the two electrodes of the EL element 503, the electrode connected to the drain region of the EL driving TFT 502 is called a pixel electrode, and the electrode connected to the counter power supply 507 is called a counter power supply.

The capacitor 504 is connected to an EL driving TF
It is formed between the gate electrode of T502 and the power supply line Vi.

FIG. 6A shows a pixel portion of a light emitting device having a plurality of pixels shown in FIG. The pixel portion 506 has source signal lines S1 to Sx, power supply lines V1 to Vx, write gate signal lines Ga1 to Gay, and erase gate signal lines Ge1 to Gay. In the pixel portion 506, a plurality of pixels 505 are formed in a matrix.

FIG. 6B shows the operation of the TFT in each pixel and the level of the voltage input to the power supply line Vi and the counter electrode when the defective portion of the EL element 503 is repaired. E
When repairing a defective portion of the L element 503, both the switching TFT 501a and the EL driving TFT 502 of each pixel are turned on. Also, the TF for erasing each pixel
T501b is turned off. Then, by making the voltage of the power supply line Vi constant and changing the voltage of the counter electrode at regular intervals, a predetermined reverse bias current flows through the EL element 503 at regular intervals.

The repair of the defect of the EL element 503 may be performed simultaneously for all the pixels 505 included in the pixel portion 506, or may be performed for each line or each pixel.

By using the method of the present invention, the EL
Pinholes are formed by the influence of dust and the like during layer formation,
Even if the two layers formed with the light emitting layer interposed therebetween are short-circuited, the short-circuited defect portion is changed to a denatured layer,
The resistance can be increased, and the current actually flowing to the EL layer when a forward bias voltage is applied to the EL element can be increased. Therefore, according to the repair method of the present invention,
Even if a defective portion exists, the light emission luminance when the same voltage is applied can be increased.

Further, since current always flows in the defective portion, deterioration of the EL layer around the defective portion is easily promoted. However, since the denatured layer has a high resistance R _SC , it is difficult for a current to flow, thereby preventing the deterioration of the EL layer around the denatured layer from being promoted.

(Embodiment 3) In this embodiment, the configuration of a driving circuit for driving the pixel portion of the light emitting device shown in Embodiment 1 will be described. Note that the source signal line driving circuit and the gate signal line driving circuit for driving the pixel portion in Embodiment 1 are not limited to the structure described in this embodiment.

FIG. 7 is a block diagram showing a driving circuit of the light emitting device of this embodiment. 7A, a source signal line driver circuit 601 includes a shift register 602, a latch (A) 603, and a latch (B) 604.

In the source signal line driver circuit 601, a clock signal (CLK) and a start pulse (SP) are input to the shift register 602. Shift register 6
02 sequentially generates a timing signal based on the clock signal (CLK) and the start pulse (SP), and sequentially supplies the timing signal to a subsequent circuit through a buffer or the like (not shown).

The timing signal from the shift register 602 is buffer-amplified by a buffer or the like. The wiring to which the timing signal is supplied has a large load capacitance (parasitic capacitance) because many circuits or elements are connected.
This buffer is provided to prevent "dulling" of the rise or fall of the timing signal caused by the large load capacitance. It is not always necessary to provide a buffer.

The timing signal buffer-amplified by the buffer is supplied to the latch (A) 603. The latch (A) 603 has a plurality of stages of latches for processing an n-bit digital video signal (a digital signal having image information). When the timing signal is input, the latch (A) 603
01, and sequentially takes in and holds an n-bit digital video signal supplied from outside.

When the digital video signal is taken into the latch (A) 603, the digital video signal may be sequentially input to the latches of a plurality of stages of the latch (A) 603. However, the present embodiment is not limited to this configuration. The latches of a plurality of stages included in the latch (A) 603 may be divided into several groups, and a so-called divided drive in which digital video signals are input simultaneously in parallel for each group may be performed. The number of groups at this time is called a division number. For example, when the latch is divided into groups for every four stages, it is referred to as divided drive in four divisions.

The time until the writing of the digital video signal to the latches of all the stages of the latch (A) 603 is completed is called a line period. Actually, the line period may include a period obtained by adding the horizontal retrace period to the line period.

When one line period ends, the latch (B)
A latch signal (Latch Signal) is supplied to 604. At this moment, the digital video signal written and held in the latch (A) 603 is simultaneously sent to the latch (B) 604, and written and held in the latches of all the stages of the latch (B) 604.

The digital video signal is latched (B) 604
The digital video signal is sequentially written into the latch (A) 603 which has been transmitted to the latch 603 based on the timing signal from the shift register 602.

During the second one line period, the digital video signal written and held in the latch (B) 603 is input to the source signal line.

FIG. 7B is a block diagram showing a configuration of the gate signal line driving circuit.

The gate signal line driving circuit 605 has a shift register 606 and a buffer 607, respectively.
In some cases, a level shifter may be provided.

In the gate signal line driving circuit 605, the timing signal from the shift register 606 is
07 and supplied to the corresponding gate signal line.
The gate signal line is connected to the gate electrode of the switching TFT of one line of pixels. Since the switching TFTs of the pixels for one line must be turned ON all at once, a buffer capable of flowing a large current is used.

When the repair method of the present invention is used, the switching TFT is turned on by controlling the signal input to the gate signal line by the gate signal line driving circuit, and the signal is input from the source signal line driving circuit to the source signal line. The EL driving TFT is turned on by a digital signal.

In this embodiment, the configuration of the driving circuit of the pixel portion shown in Embodiment 1 has been described. However, the driving circuit of the pixel portion shown in Embodiment 2 has the same configuration. Note that the pixel portion described in Embodiment 2 includes two gate signal line driver circuits, and each gate signal line driver circuit has a structure illustrated in FIG. 7B. In the case of Example 2,
Each gate signal line drive circuit controls signals input to the write gate signal line and the erase gate signal line.

(Embodiment 4) In this embodiment, the driving circuit for driving the pixel portion of the light emitting device shown in Embodiment 1 is described in Embodiment 3.
A configuration different from the case shown in FIG. Note that the source signal line driving circuit and the gate signal line driving circuit for driving the pixel portion in Embodiment 1 are not limited to the structure described in this embodiment.

FIG. 8 shows the source signal line drive circuit 6 of this embodiment.
11 shows a circuit diagram of FIG. 612 is a shift register, 613
Denotes a level shifter, and 614 denotes a sampling circuit.

A clock signal (CLK) and a start pulse signal (SP) are input to the shift register 612.
An analog signal (analog video signal) having image information is input to the sampling circuit 614.

The shift register 612 supplies a clock signal (C
LK) and the start pulse signal (SP) are input,
A timing signal is generated and input to the level shifter 613. The amplitude of the timing signal input to the level shifter 613 is amplified, and the timing signal is input to the sampling circuit 614.
Is input to

The analog video signal similarly input to the sampling circuit 614 is sampled by the timing signal input to the sampling circuit 614, and input to the corresponding source signal line.

FIG. 8B is a block diagram showing a configuration of a gate signal line driving circuit.

The gate signal line driving circuit 615 has a shift register 616 and a buffer 617, respectively.
In some cases, a level shifter may be provided.

In the gate signal line driving circuit 615, the timing signal from the shift register
17 and supplied to the corresponding gate signal line.
The gate signal line is connected to the gate electrode of the switching TFT of one line of pixels. Since the switching TFTs of the pixels for one line must be turned ON all at once, a buffer capable of flowing a large current is used.

When the repair method of the present invention is used, the switching TFT is turned on by controlling the signal input to the gate signal line by the gate signal line driving circuit, and the signal is input from the source signal line driving circuit to the source signal line. The EL driving TFT is turned on by an analog video signal.

(Embodiment 5) In this embodiment, a case where the repair method of the present invention is used for an EL element having an EL layer formed of a plurality of layers will be described.

FIG. 9A shows the structure of an EL element. First, a polythiophene derivative PEDOT having a thickness of 30 nm is formed as a hole injection layer by spin coating on an anode made of a compound of a combination of indium oxide and tin oxide (ITO). Next, MTDATA and α-NPD are each formed as a hole transport layer by vapor deposition at 20 nm and α-NPD at 10 nm. A singlet compound, Alq ₃ , is formed thereon as a light emitting material for forming a light emitting layer with a thickness of 50 nm by an evaporation method. By depositing Yb as a cathode to a thickness of 400 nm,
An EL element is formed.

When a defect due to a pinhole is formed in the light emitting layer of the EL device having the above structure, Yb serving as a cathode is replaced with α-NPD serving as a hole transport layer in the defect.
Contact with

By supplying a reverse bias current to the EL element having the defective portion at regular intervals, the temperature of the defective portion rises, and the defective portion is burned out, vaporized and evaporated, oxidized or carbonized. As a result, the defective portion turns into a denatured layer, and the resistance can be increased. Therefore, it is possible to prevent the deterioration of the EL layer existing around the modified layer from being promoted.

The light emission obtained from this EL element utilizes singlet excitation energy by a singlet compound.

FIG. 9B shows the structure of another EL element.
First, a 20-nm-thick copper phthalocyanine is formed as a hole-injecting layer by a vapor deposition method on an anode made of a compound of indium oxide and tin oxide. Next, α-NPD was formed to a thickness of 10 nm by a vapor deposition method as a hole transport layer. Ir (ppy) ₃ which is a triplet compound and CBP are used as a light emitting material for forming a light emitting layer thereon.
Is deposited to a thickness of 20 nm by a vapor deposition method. Further, 10 nm of BCP and 40 n of Alq ₃ were formed on the light emitting layer as an electron transporting layer.
m, after each formed by a vapor deposition method, Yb
Is deposited to a thickness of 400 nm to form an EL element.

When a defect due to a pinhole is formed in the light emitting layer of the EL device having the above structure, BCP which is an electron transporting layer is replaced by α which is a hole transporting layer in the defect.
-Contact with NPD.

By supplying a reverse bias current to the EL element having the defective portion at regular intervals, the temperature of the defective portion rises, and the defective portion is burned out, vaporized and evaporated, oxidized or carbonized. As a result, the defective portion becomes a denatured layer and the resistance can be increased. Therefore, it is possible to prevent the deterioration of the EL layer existing around the modified layer from being promoted.

The light emission obtained from this EL device utilizes triplet excitation energy by a triplet compound.

FIG. 10A shows the structure of an EL element. First, PEDOT, which is a polythiophene derivative, is formed as a hole injection layer to a thickness of 30 nm by spin coating on an anode made of a compound (ITO) in which indium oxide and tin oxide are combined. A singlet compound, Alq ₃ , is used as a light emitting material for forming a light emitting layer thereon.
Is formed to a thickness of 50 nm by a vapor deposition method. Then, an EL element is formed by depositing Pb as a cathode to a thickness of 400 nm.

When a defect due to a pinhole is formed in the light emitting layer of the EL device having the above structure, Pb which is a cathode at the defect is replaced by PEDOT which is a hole injection layer.
Contact with

By supplying a reverse bias current to the EL element having the defective portion at regular intervals, the temperature of the defective portion rises, and the defective portion is burned out, vaporized and evaporated, oxidized or carbonized. As a result, the defective portion turns into a denatured layer, and the resistance can be increased. Therefore, it is possible to prevent the deterioration of the EL layer existing around the modified layer from being promoted.

The light emission obtained from this EL element utilizes singlet excitation energy by a singlet compound.

FIG. 10B shows the structure of the EL element. First, Pb is deposited as a cathode to a thickness of 400 nm. A singlet compound, Alq ₃ , is formed as a light-emitting material for forming a light-emitting layer thereon by evaporation at a thickness of 50 nm. Next, as a hole injection layer, PEDOT, which is a polythiophene derivative, is formed with a thickness of 30 nm by spin coating. Then, Au is formed to a thickness of 5 nm. Note that Au is provided in order to prevent the surface of the EL layer from being deteriorated in a later step. An EL element is formed by forming an anode made of a compound of a combination of indium oxide and tin oxide (ITO) thereon.

When a defect due to a pinhole is formed in the light emitting layer of the EL device having the above structure, Pb serving as a cathode is replaced with PEDOT serving as a hole injection layer in the defect.
Contact with

The light emission obtained from this EL device utilizes singlet excitation energy by a singlet compound.

According to the present invention, a pinhole is formed due to the influence of dust or the like when the EL layer is formed, and the two layers formed with the light emitting layer interposed therebetween are short-circuited. EL by increasing the resistance of the defect
When a forward bias voltage is applied to the element, the current actually flowing to the EL layer can be increased. Therefore, according to the repair method of the present invention, even when a defective portion exists, the light emission luminance when the same voltage is applied can be increased.

Further, by increasing the resistance by changing the defective portion to a modified layer, it is possible to prevent the deterioration of the EL layer existing around the modified layer from being promoted.

The carbide formed by carbonizing the EL material has high insulating properties and is stable as a substance. Therefore, the repair method of the present invention is particularly effective when the organic EL material is filled in the defective portion, for example, when a defective portion occurs when the EL material is formed so as to be in contact with the EL layer.

This embodiment can be implemented by freely combining with Embodiments 1 to 4.

(Embodiment 6) In a light emitting device using the repair method of the present invention, it is possible to use an EL material capable of utilizing phosphorescence from triplet excitons for light emission. A light-emitting device using an EL material capable of utilizing phosphorescence for light emission can dramatically improve external light-emitting quantum efficiency. Thus, low power consumption, long life, and light weight of the EL element can be achieved.

Here, a report is shown in which the triplet exciton is used to improve the external light emission quantum efficiency. (T.Tsutsui, C.Adac
hi, S. Saito, Photochemical Processes in Organized
Molecular Systems, ed.K. Honda, (Elsevier Sci. Pub.,
Tokyo, 1991) p.437.)

The molecular formula of the EL material (coumarin dye) reported in the above article is shown below.

[0127]

Embedded image

(MABaldo, DFO'Brien, Y. You, A. Shou
stikov, S. Sibley, METhompson, SRForrest, Nature
395 (1998) p.151.)

The EL materials (P
The molecular formula of (t complex) is shown below.

[0130]

Embedded image

(MABaldo, S. Lamansky, PEBurrrows,
METhompson, SRForrest, Appl.Phys.Lett., 75 (199
9) p.4.) (T.Tsutsui, M.-J.Yang, M.Yahiro, K.Nakamu
ra, T.Watanabe, T.tsuji, Y.Fukuda, T.Wakimoto, S.Ma
yaguchi, Jpn.Appl.Phys., 38 (12B) (1999) L1502.)

The EL materials (I
The molecular formula of (r complex) is shown below.

[0133]

Embedded image

As described above, if the phosphorescence emission from the triplet exciton can be used, it is possible in principle to realize a high external emission quantum efficiency three to four times higher than the case where the fluorescence emission from the singlet exciton is used. .

The structure of this embodiment can be implemented by freely combining with any of the structures of Embodiments 1 to 5.

(Embodiment 7) In this embodiment, voltage-current characteristics when a reverse bias voltage is actually applied to an EL element having a defective portion will be described.

The EL device used in this example was prepared from a compound (ITO) obtained by combining indium oxide and tin oxide.
Copper phthalocyanine is formed as a hole injection layer with a thickness of 20 nm by an evaporation method on the anode made of. Next, MTDATA of 20 nm and α-N
PD is formed to a thickness of 10 nm by a vapor deposition method. A singlet compound, Alq _3, having a thickness of 50 nm is formed thereon by a vapor deposition method as a light emitting material for forming a light emitting layer. Next, an EL element is formed by depositing lithium acetylacetonate (Liacac) to a thickness of 2 nm as an electron injection layer and an aluminum alloy to a thickness of 50 nm as a cathode.

FIG. 14 shows voltage-current characteristics when a reverse bias voltage is applied to the EL element having the above configuration. At Point A where the reverse bias voltage is −5 V, the reverse bias current increases and then decreases again.

Even when the EL element is destroyed by applying a reverse bias voltage, the reverse bias current is considered to increase. However, in Point A, since the current value decreases thereafter, the defective portion has It can be considered that some change has occurred and the resistance of the defective portion has increased.

In the repair method of the present invention, the height of the reverse bias voltage applied to the EL element and the time for applying the reverse bias vary depending on the materials and constitutions of the anode, cathode and EL layer of the EL element. If the reverse bias voltage is too low, the effect of the present invention cannot be obtained. Conversely, if the reverse bias voltage is too high, the deterioration of the EL layer is promoted or the EL element itself is destroyed.

In the voltage-current characteristics shown in FIG. 14, the reverse bias current sharply increases in the region where the reverse bias voltage is -6.5 V or less. Therefore, in the case of the EL element used in this embodiment, when a reverse bias voltage of -6.5 V or less is applied, it is considered that the EL element is being destroyed or the EL layer is being deteriorated.

The practitioner needs to appropriately set the height of the reverse bias voltage and the application time depending on the materials and structures of the anode, cathode, and EL layer of the EL element.

(Embodiment 8) In this embodiment, a description will be given of a voltage-current characteristic in the case where the value of the reverse bias voltage is increased to the avalanche voltage (V _av ) by direct current and then reduced again.

[0144] Figure 15, the value of the reverse bias voltage is increased until avalanche voltage direct current (V _av), when began to decrease again, the voltage - shows a graph of current characteristics. As the reverse bias voltage is increased, Point B, P
In point C and Point D, the reverse bias current I _rev temporarily becomes large, and some change occurs in the defective portion to change to the denatured layer.

Even if the reverse bias voltage V _rev is increased to V _{av and} then reduced again, no particular change is observed in the reverse bias current I _rev .

This embodiment can be implemented by freely combining with Embodiments 1 to 7.

(Embodiment 9) In this embodiment, a sectional view of a light emitting device using the repair method of the present invention will be described.

In FIG. 16, a switching TFT 721 provided on a substrate 700 is formed using an n-channel TFT.

In this embodiment, the switching TFT is used.
Although 721 has a double gate structure in which two channel formation regions are formed, a single gate structure in which one channel formation region is formed or a triple gate structure in which three channel formation regions are formed may be used.

[0150] A driver circuit provided over the substrate 700 includes an n-channel TFT 723 and a p-channel TFT 724. In this embodiment, the TFT included in the driving circuit
Has a single gate structure, but may have a double gate structure or a triple gate structure.

The wirings 701 and 703 function as a source wiring of a CMOS circuit, and the wiring 702 functions as a drain wiring.
The wiring 704 functions as a wiring for electrically connecting the source wiring 708 and the source region of the switching TFT, and the wiring 705 functions as a wiring for electrically connecting the drain wiring 709 and the drain region of the switching TFT. I do.

The EL driving TFT 722 is formed using a p-channel TFT. In this embodiment, E
Although the L driving TFT 722 has a single gate structure, it may have a double gate structure or a triple gate structure.

Further, a wiring 706 is a source wiring (corresponding to a current supply line) of the EL driving TFT, and 707 is E
This electrode is electrically connected to the pixel electrode 710 by being overlapped on the pixel electrode 710 of the L driving TFT.

Reference numeral 710 denotes a pixel electrode (anode of an EL element) made of a transparent conductive film. As a transparent conductive film,
A compound of indium oxide and tin oxide, a compound of indium oxide and zinc oxide, zinc oxide, tin oxide, or indium oxide can be used. Further, a material obtained by adding gallium to the transparent conductive film may be used. The pixel electrode 710 has a flat interlayer insulating film 7 before forming the wiring.
11 is formed. In this embodiment, it is very important to flatten the step due to the TFT using the flattening film 711 made of resin. Since an EL layer formed later is extremely thin, poor light emission may be caused by the presence of a step. Therefore, it is desirable that the EL layer be flattened before forming the pixel electrode so that the EL layer can be formed as flat as possible.

After forming the wirings 701 to 707, a bank 712 is formed as shown in FIG. Bank 712 is 10
The insulating film or the organic resin film containing silicon having a thickness of 0 to 400 nm may be formed by patterning.

Since the bank 712 is an insulating film,
Attention must be paid to electrostatic breakdown of the element during film formation.
In this embodiment, the resistivity is reduced by adding carbon particles or metal particles to the insulating film used as the material of the bank 712 to suppress the generation of static electricity. At this time, the resistivity is 1 × 10 ⁶ to 1 × 1.
The addition amount of the carbon particles and metal particles may be adjusted so as to be 0 ¹² Ωm (preferably 1 × 10 ⁸ to 1 × 10 ¹⁰ Ωm).

An EL layer 713 is formed on the pixel electrode 710. Although only one pixel is shown in FIG. 16, in this embodiment, EL layers corresponding to R (red), G (green), and B (blue) are separately formed. In this embodiment, a low-molecular organic EL material is formed by an evaporation method.
Specifically, a 20-nm-thick copper phthalocyanine (CuPc) film was provided as the hole injection layer 713a, and a 70-nm-thick tris-8-quinolinolato aluminum complex (Alq ₃ ) film was provided thereon as the light-emitting layer 713b. It has a laminated structure. Quinacridone in Alq _3, perylene or D
The emission color can be controlled by adding a fluorescent dye such as CM1.

However, the above example is an example of the organic EL material that can be used for the EL layer, and it is not necessary to limit the invention to this. An EL layer (a layer for performing light emission and carrier movement therefor) may be formed by freely combining a light emitting layer, a charge transport layer, or a charge injection layer. For example, in this embodiment, a low molecular organic EL material is
Although an example in which the layer is used as a layer has been described, a polymer organic EL material may be used. It is also possible to use an inorganic material such as silicon carbide for the charge transport layer and the charge injection layer. Known materials can be used for these organic EL materials and inorganic materials.

Next, a cathode 714 made of a conductive film is provided on the EL layer 713. In this embodiment, an alloy film of aluminum and lithium is used as the conductive film. Of course, a known MgAg film (an alloy film of magnesium and silver)
May be used. As the cathode material, a conductive film made of an element belonging to Group 1 or 2 of the periodic table or a conductive film to which those elements are added may be used.

When the cathode 714 is formed, EL
The element 719 is completed. Note that the EL element 71 here
Reference numeral 9 denotes a capacitor formed by the pixel electrode (anode) 710, the EL layer 713, and the cathode 714.

It is effective to provide the passivation film 716 so as to completely cover the EL element 719. As the passivation film 716, an insulating film including a carbon film, a silicon nitride film, or a silicon nitride oxide film is used, and the insulating film is used in a single layer or in a stacked layer.

At this time, a film having good coverage is preferably used as a passivation film, and a carbon film, in particular, a D film is preferably used.
It is effective to use an LC (diamond-like carbon) film. Since the DLC film can be formed in a temperature range from room temperature to 100 ° C. or lower, it can be easily formed above the EL layer 713 having low heat resistance. In addition, the DLC film has a high blocking effect against oxygen, and the EL layer 713
Can be suppressed. Therefore, the problem that the EL layer 713 is oxidized during the subsequent sealing step can be prevented.

Furthermore, a sealing material 717 is provided on the passivation film 716, and a cover material 718 is attached. As the sealing material 717, an ultraviolet curable resin may be used, and it is effective to provide a substance having a moisture absorbing effect or a substance having an antioxidant effect inside. In this embodiment, a cover material 718 having a carbon film (preferably a diamond-like carbon film) formed on both surfaces of a glass substrate, a quartz substrate, or a plastic substrate (including a plastic film) is used.

Thus, an EL display device having a structure as shown in FIG. 16 is completed. After forming the bank 712,
It is effective to continuously process the steps up to the formation of the passivation film 716 without exposing to the atmosphere using a multi-chamber type (or in-line type) film forming apparatus. Further, by further developing, it is also possible to continuously perform processing up to the step of bonding the cover material 718 without releasing to the atmosphere.

The features of the TFT in this embodiment are as follows.
The gate electrode is formed from a two-layered conductive film, and in the low-concentration impurity region provided between the channel formation region and the drain region, there is almost no difference in concentration and a gentle concentration gradient. A region (GOLD region) that overlaps the electrode and a region (L
DD area). Further, a peripheral portion of the gate insulating film, that is, a region not overlapping with the gate electrode and a region above the high-concentration impurity region are tapered.

In the light emitting device of this embodiment, the light emitting layer 713
If a pinhole is formed in b, a defective portion where the hole injection layer 713a and the cathode 714 are in contact via the pinhole is formed. According to the repair method of the present invention, the resistance can be increased by changing the defective portion to the denatured layer 715. Therefore, the luminance of the portion other than the pinhole of the pixel can be increased, and the deterioration of the EL layer around the pinhole can be prevented from being promoted.

In this embodiment, only the configuration of the pixel portion and the driving circuit is shown. However, according to the manufacturing process of this embodiment, other components such as a signal dividing circuit, a D / A converter, an operational amplifier, a gamma correction circuit, and the like can be used. Can be formed on the same insulator, and a memory and a microprocessor can also be formed.

The configuration of the present embodiment is similar to that of the first, second, and third embodiments.
It can be implemented in any combination with 3, 4, 6 or 8.

(Embodiment 10) In this embodiment, a sectional view of a light emitting device using the repair method of the present invention will be described.

In FIG. 17, a p-channel TFT 200 and an n-channel TFT of a driving circuit are formed on the same substrate.
201, a TFT 203 for EL driving of a pixel portion, a TFT 204 for switching, and a storage capacitor 205 are formed.

In the p-channel TFT 200 of the driver circuit, the conductive layer 220 having the second tapered shape has a function as a gate electrode, and the channel forming region 20
6. Third function as source or drain region
Impurity region 207a, and fourth impurity region (A) 207 forming an LDD region that does not overlap with gate electrode 220
b, a structure having a fourth impurity region (B) 207c forming an LDD region partly overlapping with the gate electrode 220.

In the n-channel TFT 201, a conductive layer 221 having a second tapered shape has a function as a gate electrode, and a first impurity region functioning as a channel formation region 208 and a source or drain region. 209 a, a second impurity region (A) (A) 209 b forming an LDD region not overlapping with the gate electrode 221, and a second impurity region (A) 209 b forming an LDD region partially overlapping the gate electrode 221
Having an impurity region (B) 209c. For the channel length of 2 to 7 μm, the length of the portion where the second impurity region (B) 209c overlaps with the gate electrode 221 is 0.1 to 0.3 μm. The length of Lov is controlled from the thickness of the gate electrode 221 and the angle of the tapered portion. n
By forming such an LDD region in a channel type TFT, a high electric field generated in the vicinity of the drain region can be reduced to prevent generation of hot carriers and prevent deterioration of the TFT.

Similarly, in the EL driving TFT 203, the conductive layer 223 having the second tapered shape has a function as a gate electrode, and the third impurity which functions as a channel formation region 212, a source region or a drain region. A structure including a region 213a, a fourth impurity region (A) 213b forming an LDD region not overlapping with the gate electrode 223, and a fourth impurity region (B) 213c forming an LDD region partially overlapping with the gate electrode 223; Has become.

The driving circuit is formed by a logic circuit such as a shift register circuit or a buffer circuit, or a sampling circuit formed by an analog switch. In FIG. 17, the TFTs forming them are shown in a single-gate structure in which one gate electrode is provided between a pair of sources and drains. However, a multi-gate structure in which a plurality of gate electrodes are provided between a pair of sources and drains is shown. No problem.

The drain region of the EL driving TFT 203 is connected to the pixel electrode 271 via the wiring 231.
An EL layer 272 made of a known organic EL material is formed so as to be in contact with the pixel electrode 271, and a cathode 273 is formed so as to be in contact with the EL layer 272.

In the switching TFT 204, a conductive layer 224 having a second tapered shape has a function as a gate electrode, and the channel forming regions 214a and 21a.
4b, first impurity regions 215a and 217 functioning as a source region or a drain region, a second impurity region (A) 215b forming an LDD region not overlapping with the gate electrode 224, and an LD partially overlapping the gate electrode 224.
The structure has a second impurity region (B) 215c that forms the D region. Second impurity region (B) 213
The length of the portion where c overlaps with the gate electrode 224 is 0.1 to
0.3 μm. Further, a semiconductor extending from the first impurity region 217 and having a second impurity region (A) 219b, a second impurity region (B) 219c, and a region 218 to which an impurity element which determines a conductivity type is not added. Layer and third
A storage capacitor is formed from an insulating layer formed of the same layer as the gate insulating film having the shape of, and a capacitor wiring 225 formed of the second tapered conductive layer.

In the light emitting device of this embodiment, the EL layer 272
When a pinhole is formed in the pixel electrode, a defective portion where the pixel electrode 271 and the cathode 273 are in contact via the pinhole is formed. According to the repair method of the present invention, the resistance can be increased by changing the defective portion to the denatured layer 274. Therefore, the luminance of the portion other than the pinhole of the pixel can be increased, and the deterioration of the EL layer around the pinhole can be prevented from being promoted.

The configuration of the present embodiment is similar to that of Embodiments 1, 2,
It can be implemented in any combination with 3, 4, 6 or 8.

(Embodiment 11) In this embodiment, a sectional view of a light emitting device using the repair method of the present invention will be described.

In FIG. 18, reference numeral 811 denotes a substrate, and 812, an insulating film serving as a base (hereinafter, referred to as a base film). As the substrate 811, a light-transmitting substrate, typically, a glass substrate, a quartz substrate, a glass ceramic substrate, or a crystallized glass substrate can be used. However, it must withstand the maximum processing temperature during the manufacturing process.

The base film 812 is particularly effective when a substrate containing mobile ions or a substrate having conductivity is used, but need not be provided on a quartz substrate. Base film 812
May be used as an insulating film containing silicon (silicon). Note that, in this specification, the “insulating film containing silicon” refers specifically to silicon such as a silicon oxide film, a silicon nitride film, or a silicon nitride oxide film (SiOxNy: x and y are arbitrary integers). On the other hand, it refers to an insulating film containing oxygen or nitrogen at a predetermined ratio.

Reference numeral 8201 denotes a switching TFT;
Reference numeral 2 denotes an EL driving TFT, each of which is an n-channel TFT.
It is formed of FT and p-channel TFT. In the case where the EL emission direction is the lower surface of the substrate (the surface on which the TFT and the EL layer are not provided), the above structure is preferable. However, the present invention is not limited to this configuration. T for switching
FT and EL driving TFTs are p-channel even for n-channel TFTs.
Either channel type TFT may be used.

The switching TFT 8201 includes a source region 813, a drain region 814, and an LDD region 815a.
To 815d, the isolation region 816 and the channel formation region 86
3, 864, an active layer including a gate insulating film 818, gate electrodes 819a and 819b, and a first interlayer insulating film 820.
And a source signal line 821 and a drain wiring 822. Note that the gate insulating film 818 or the first interlayer insulating film 820 may be common to all TFTs on the substrate,
It may be different depending on the circuit or element. 817
Reference numerals a and 817b denote masks for forming a channel formation region.

The switching TFT shown in FIG.
Reference numeral 8201 denotes a so-called double gate structure in which gate electrodes 819a and 819b are electrically connected.
Of course, not only a double gate structure but also a so-called multi-gate structure such as a triple gate structure (a structure including an active layer having two or more channel formation regions connected in series)
It may be.

The multi-gate structure is extremely effective in reducing the off-state current. If the off-state current of the switching TFT is sufficiently reduced, the EL driving TFT 820 is accordingly reduced.
The minimum capacitance required by the capacitor connected to the second gate electrode can be suppressed. That is, since the area of the capacitor can be reduced, the multi-gate structure is effective in increasing the effective light emitting area of the EL element.

Further, in the switching TFT 8201, the LDD regions 815a to 815d are provided so as not to overlap the gate electrodes 819a and 819b via the gate insulating film 818. Such a structure is very effective in reducing off-state current. Also, the LDD region 815a
The length (width) of .about.815d may be 0.5-3.5 .mu.m, typically 2.0-2.5 .mu.m.

It is more preferable to provide an offset region (a region made of a semiconductor layer having the same composition as the channel formation region and to which a gate voltage is not applied) between the channel formation region and the LDD region from the viewpoint of reducing off-state current. . Also,
In the case of a multi-gate structure having two or more gate electrodes, an isolation region 816 provided between channel formation regions
(A region where the same impurity element is added at the same concentration as the source region or the drain region) is effective in reducing off-state current.

Next, the EL driving TFT 8202 includes an active layer including a source region 826, a drain region 827, and a channel formation region 805, a gate insulating film 818, a gate electrode 830, a first interlayer insulating film 820, It is formed to have a wiring 831 and a drain wiring 832.
In this embodiment, the EL driving TFT 8202 is a p-channel TFT. Note that reference numeral 829 is a mask for forming a channel formation region.

The drain region 814 of the switching TFT 8201 is electrically connected to the gate 830 of the EL driving TFT 8202. Although not shown, specifically, the gate electrode 830 of the EL driving TFT 8202 is electrically connected to the drain region 814 of the switching TFT 8201 via a drain wiring (also referred to as a connection wiring) 822. The gate electrode 83
0 has a single gate structure, but may have a multi-gate structure. In addition, the EL driving TFT 8202
Are connected to a power supply line (not shown).

The EL driving TFT 8202 is an element for controlling the amount of current injected into the EL element, and a relatively large amount of current flows. Therefore, it is preferable that the channel width (W) is designed to be larger than the channel width of the switching TFT. Further, it is preferable that the channel length (L) is designed to be long so that an excessive current does not flow to the EL driving TFT 8202. Desirably 0.5 per pixel
２2 μA (preferably 1 to 1.5 μA).

Further, the thickness of the active layer (particularly, the channel formation region) of the EL driving TFT 8202 is increased (preferably 50 to 100 nm, more preferably 60 to 8 nm).
0 nm), deterioration of the TFT may be suppressed.
Conversely, in the case of the switching TFT 8201, from the viewpoint of reducing the off-state current, the thickness of the active layer (particularly, the channel formation region) is reduced (preferably 20 to 5).
0 nm, more preferably 25 to 40 nm) is also effective.

The structure of the TFT provided in the pixel has been described above. At this time, a drive circuit is also formed. FIG. 18 shows a CM which is a basic unit forming a drive circuit.
The OS circuit is shown.

In FIG. 18, a TFT having a structure for reducing hot carrier injection while keeping the operating speed as low as possible is replaced with an n-channel type TFT 82 of a CMOS circuit.
04. Note that the driver circuit here refers to a source signal side driver circuit and a gate signal side driver circuit. Of course, other logic circuits (such as a level shifter, an A / D converter, and a signal dividing circuit) can be formed.

N-channel TFT 820 of CMOS circuit
The active layer 4 has a source region 835 and a drain region 83.
6, including an LDD region 837 and a channel formation region 862, and the LDD region 837 overlaps with the gate electrode 839 via the gate insulating film 818. 838 is a mask for forming a channel formation region.

The LDD region 8 is formed only on the drain region 836 side.
The reason why 37 is formed is that the operation speed is not reduced. In addition, the n-channel TFT 8204 does not need to care much about the off-state current value, and it is better to emphasize the operation speed. Therefore, the LDD region 837
Is completely overlapped with the gate electrode, and it is desirable to reduce the resistance component as much as possible. That is, it is better to eliminate the so-called offset.

Also, a p-channel type TFT of a CMOS circuit
In the case of 8205, the deterioration due to hot carrier injection is hardly noticeable, so that an LDD region does not need to be provided. Therefore, the active layer includes a source region 840, a drain region 841, and a channel formation region 861, over which a gate insulating film 818 and a gate electrode 843 are provided. Of course, n
An LDD region is provided similarly to the channel type TFT 8204,
It is also possible to take hot carrier measures. In addition,
842 is a mask for forming a channel formation region.

The n-channel TFT 8204 and the p-channel TFT
Each of the channel type TFTs 8205 has a source wiring 844 on a source region with a first interlayer insulating film 820 therebetween.
845. Further, an n-channel TFT 8204 and a p-channel TFT 8
The drain region 205 is electrically connected to each other.

Next, reference numeral 847 denotes a first passivation film having a thickness of 10 nm to 1 μm (preferably 200 to 5 μm).
00 nm). As a material, an insulating film containing silicon (especially a silicon nitride oxide film or a silicon nitride film is preferable)
Can be used. This passivation film 847
Has a role of protecting the formed TFT from alkali metals and moisture. Finally, the TFT (especially the EL driving T
The EL layer provided above the FT) contains an alkali metal such as sodium. That is, the first passivation film 847 converts these alkali metals (mobile ions) to T
It also functions as a protective layer that does not penetrate the FT side.

Reference numeral 848 denotes a second interlayer insulating film.
It has a function as a flattening film for flattening a step formed by FT. As the second interlayer insulating film 848, an organic resin film is preferable, and polyimide, polyamide, acrylic, BCB (benzocyclobutene), or the like is preferably used.
These organic resin films have an advantage that a good flat surface is easily formed and the relative dielectric constant is low. Since the EL layer is very sensitive to unevenness, it is desirable that the step due to the TFT is almost completely absorbed by the second interlayer insulating film 848. In order to reduce the parasitic capacitance formed between the gate signal line or the data signal line and the cathode of the EL element, it is desirable to provide a thick material having a low relative dielectric constant. Therefore, the film thickness is 0.
5-5 μm (preferably 1.5-2.5 μm) is preferred.

Reference numeral 849 denotes a pixel electrode (anode of an EL element) made of a transparent conductive film, which is formed after opening a contact hole (opening) in the second interlayer insulating film 848 and the first passivation film 847. The opening is formed so as to be connected to the drain wiring 832 of the EL driving TFT 8202. If the pixel electrode 849 and the drain region 827 are not directly connected as shown in FIG. 18, it is possible to prevent the alkali metal of the EL layer from entering the active layer via the pixel electrode.

A third interlayer insulating film 85 made of a silicon oxide film, a silicon nitride oxide film or an organic resin film is formed on the pixel electrode 849.
0 is provided for a thickness of 0.3-1 μm. The third interlayer insulating film 850 has an opening formed by etching on the pixel electrode 849, and the edge of the opening is etched so as to have a tapered shape. The taper angle is 10-60
° (preferably 30 to 50 °).

The EL layer 85 is formed on the third interlayer insulating film 850.
1 is provided. The EL layer 851 is used in a single layer or a stacked structure; however, the use of the EL layer 851 in a stacked structure has higher luminous efficiency. Generally, a hole injection layer / a hole transport layer / a light emitting layer / an electron transport layer are formed in this order on a pixel electrode. A structure such as a hole transport layer / light emitting layer / electron transport layer / electron injection layer may be used. In the present invention, any known structure may be used, and the EL layer may be doped with a fluorescent dye or the like.

The structure shown in FIG. 18 is an example in the case where a method of forming three types of EL elements corresponding to RGB is used. Although only one pixel is shown in FIG. 18, pixels having the same structure are formed corresponding to the respective colors of red, green, and blue, whereby color display can be performed. The present invention can be implemented regardless of the light emitting method.

On the EL layer 851, the cathode 85 of the EL element is provided.
2 are provided. As the cathode 852, a material containing magnesium (Mg), lithium (Li), or calcium (Ca) having a small work function is used. Preferably Mg
An electrode made of Ag (a material obtained by mixing Mg and Ag at a ratio of Mg: Ag = 10: 1) may be used. Other examples include a MgAgAl electrode, a LiAl electrode, and a LiFAl electrode.

Note that the pixel electrode (anode) 849 and the EL layer 8
An EL element 8206 is formed by 51 and the cathode 852.

The EL layer 851 must be formed individually for each pixel. However, since the EL layer 851 is extremely weak against moisture,
Normal photolithography technology cannot be used. Therefore, it is preferable to selectively form the film by a vapor phase method such as a vacuum evaporation method, a sputtering method, and a plasma CVD method using a physical mask material such as a metal mask.

As a method for selectively forming the EL layer, an ink jet method, a screen printing method, a spin coating method, or the like can be used. However, since these methods cannot continuously form a cathode at present, the above-described method is used. It can be said that the method is more preferable.

Reference numeral 853 denotes a protective electrode,
51, an electrode for protecting the cathode 852 from external moisture and the like and for connecting the cathode 852 of each pixel.
As the protective electrode 853, a low-resistance material including aluminum (Al), copper (Cu), or silver (Ag) is preferably used. This protective electrode 853 can also be expected to have a heat radiation effect of reducing heat generation of the EL layer.

Further, reference numeral 854 denotes a second passivation film having a thickness of 10 nm to 1 μm (preferably 200 to 5 μm).
00 nm). Second passivation film 85
The purpose of providing 4 is mainly to protect the EL layer 851 from moisture, but it is also effective to have a heat radiation effect. However, since the EL layer is weak to heat as described above, the temperature is preferably as low as possible (preferably in a temperature range from room temperature to 120 ° C.).
It is desirable to form a film. Therefore, the plasma CVD method,
It can be said that a sputtering method, a vacuum evaporation method, an ion plating method or a solution coating method (spin coating method) is a desirable film forming method.

Note that all the TFTs shown in FIG.
It goes without saying that the polysilicon film used in the present invention may be provided as an active layer.

In the light emitting device of this embodiment, the EL layer 860
When a pinhole is formed in the pixel electrode, a defective portion where the pixel electrode 849 and the cathode 852 are in contact with each other through the pinhole is formed. According to the repair method of the present invention, the resistance can be increased by changing the defective portion to the denatured layer 860. Therefore, the luminance of the portion other than the pinhole of the pixel can be increased, and the deterioration of the EL layer around the pinhole can be prevented from being promoted.

The structure of the present embodiment is similar to that of Embodiments 1, 2,
It can be implemented in any combination with 3, 4, 6 or 8.

Embodiment 12 Since a light emitting device using an EL element is of a self-luminous type, it has better visibility in a bright place and a wider viewing angle than a liquid crystal display device. Therefore, it can be used for display portions of various electronic devices.

Electronic equipment using the light emitting device using the repair method of the present invention include a video camera, a digital camera, a goggle type display (head mounted display), a navigation system, a sound reproducing device (car audio, audio component, etc.), Note-type personal computers, game machines, portable information terminals (mobile computers, mobile phones, portable game machines, electronic books, etc.), and image reproducing devices provided with recording media (specifically, Digi
Play a recording medium such as tal Versatile Disc (DVD),
A device provided with a display device capable of displaying the image). In particular, for portable information terminals that often view the screen from an oblique direction, the wide viewing angle is regarded as important.
It is desirable to use a light emitting device having an element. FIG. 11 shows specific examples of these electronic devices.

FIG. 11A shows an EL display device, which includes a housing 2001, a support base 2002, a display portion 2003, a speaker portion 2004, a video input terminal 2005, and the like. The light-emitting device using the repair method of the present invention can be used for the display portion 2003. Since a light-emitting device having an EL element is a self-luminous type, it does not require a backlight and can have a thinner display portion than a liquid crystal display device. Note that the EL display device includes all information display devices for personal computers, TV broadcast reception, advertisement display, and the like.

FIG. 11B shows a digital still camera, which includes a main body 2101, a display portion 2102, an image receiving portion 2103,
An operation key 2104, an external connection port 2105, a shutter 2106, and the like are included. A light-emitting device using the repair method of the present invention can be used for the display portion 2102.

FIG. 11C shows a notebook personal computer, which includes a main body 2201, a housing 2202, and a display portion 2.
203, keyboard 2204, external connection port 220
5, including a pointing mouse 2206 and the like. A light-emitting device using the repair method of the present invention can be used for the display portion 2203.

FIG. 11D shows a mobile computer, which includes a main body 2301, a display portion 2302, and a switch 230.
3, an operation key 2304, an infrared port 2305, and the like. The light emitting device using the repair method of the present invention is a display unit 230.
2 can be used.

FIG. 11E shows a portable image reproducing apparatus (specifically, a DVD reproducing apparatus) provided with a recording medium, and includes a main body 2401, a housing 2402, a display portion A 2403, a display portion B 2404, and a recording medium ( DVD, etc.) reading unit 240
5, operation keys 2406, a speaker unit 2407, and the like. The display portion A2403 mainly displays image information, and the display portion B2404 mainly displays character information. However, the light-emitting device using the repair method of the present invention uses these display portions A and B2.
403, 2404. Note that the image reproducing device provided with the recording medium includes a home game machine and the like.

FIG. 11F shows a goggle type display (head mounted display),
1, including a display unit 2502 and an arm unit 2503. The light-emitting device using the repair method of the present invention can be used for the display portion 2502.

FIG. 11G shows a video camera, which includes a main body 2601, a display portion 2602, a housing 2603, an external connection port 2604, a remote control receiving portion 2605, and an image receiving portion 260.
6, a battery 2607, a voice input unit 2608, operation keys 2609, and the like. The light-emitting device using the repair method of the present invention can be used for the display portion 2602.

[0222] Here, FIG. 11H illustrates a mobile phone, which includes a main body 2701, a housing 2702, a display portion 2703, a voice input portion 2704, a voice output portion 2705, operation keys 2706,
An external connection port 2707, an antenna 2708, and the like are included.
A light-emitting device using the repair method of the present invention can be used for the display portion 2703. Note that the display portion 2703 displays white characters on a black background, so that power consumption of the mobile phone can be suppressed.

If the emission luminance of the EL material becomes higher in the future, it becomes possible to enlarge and project the light containing the output image information with a lens or the like and use it for a front-type or rear-type projector.

[0224] The electronic device may be the Internet or C.
Information distributed through an electronic communication line such as an ATV (cable television) is often displayed, and in particular, opportunities to display moving image information are increasing. Since the response speed of the EL material is extremely high, the light-emitting device is preferable for displaying moving images.

[0225] In the light emitting device, since the light emitting portion consumes power, it is desirable to display information so that the light emitting portion is reduced as much as possible. Therefore, when a light emitting device is used for a portable information terminal, particularly a display portion mainly for character information such as a mobile phone or a sound reproducing device, the light emitting portion is driven to form character information with a non-light emitting portion as a background. It is desirable to do.

As described above, the applicable range of the light emitting device using the repair method of the present invention is extremely wide, and the light emitting device can be used for electronic devices in various fields. Further, the electronic apparatus of the present embodiment may use any of the configurations shown in Embodiments 1 to 11.

(Embodiment 13) In this embodiment, a case where the repair method of the present invention is applied to a passive type (simple matrix type) light emitting device will be described.

[0228] FIG. 19A illustrates a structure of a passive light-emitting device. A pixel portion 805 includes a plurality of pixels 806. Each pixel has one of a plurality of data lines 803,
And one of the plurality of scanning lines 804. Data line 8
An EL layer is formed between the pixel line 03 and the scanning line 804, and the data line 803 and the scanning line 804 serve as electrodes, and an EL element 807 is formed.

The signal input to the data line 803 is controlled by the data line driving circuit 801 and
4 is controlled by the scanning line driving circuit 802.

FIG. 19B shows the voltage levels of signals input to the scanning lines 804 and the data lines 803 when the repair method of the present invention is used. By keeping the voltage of each scanning line 804 constant and changing the voltage of the data line every fixed period, a predetermined reverse bias current flows through the EL element 807 every fixed period.

The repair of the defect of the EL element 807 may be performed simultaneously for all the pixels 806 included in the pixel portion 805, or may be performed for each line or each pixel.

By using the method of the present invention, the EL
Pinholes are formed by the influence of dust and the like during layer formation,
Even if the two layers formed with the light emitting layer interposed therebetween are short-circuited, the resistance of the short-circuited defective portion can be increased, and when the forward bias voltage is applied to the EL element, the EL layer is actually Current flowing through the motor can be increased. Therefore, according to the repair method of the present invention, even when a defective portion exists, the light emission luminance when the same voltage is applied can be increased.

Further, since current always flows in the defective portion, deterioration of the EL layer existing around the defective portion is easily promoted. However, since the denatured layer has a high resistance R _SC , it is difficult for a current to flow, thereby preventing the deterioration of the EL layer around the denatured layer from being promoted.

This embodiment can be implemented by freely combining with Embodiments 5 to 8, and 12.

[0235]

According to the present invention, a pinhole is formed by the influence of dust or the like during the formation of an EL layer due to the above structure, and even if two layers formed with a light emitting layer interposed therebetween are short-circuited, short-circuiting occurs. The resistance of the defective portion can be increased, and the current actually flowing to the EL layer when a forward bias voltage is applied to the EL element can be increased. Therefore, according to the repair method of the present invention, even if a defective portion exists,
The light emission luminance when the same voltage is applied can be increased.

Further, since current always flows in the defective portion, deterioration of the EL layer existing around the defective portion is easily promoted. However, since the denatured layer has a high resistance R _SC , it is difficult for a current to flow, thereby preventing the deterioration of the EL layer around the denatured layer from being promoted.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a current flow in an EL element when a reverse bias voltage is applied to the EL element.

FIG. 2 is a diagram schematically showing a change in a voltage-current characteristic of an EL element in a process of repair and a current flow in the EL element when a forward bias voltage is applied to the EL element after repair.

FIG. 3 is a circuit diagram of a pixel.

FIG. 4 is a circuit diagram of a pixel portion and an operation of the pixel portion at the time of repair.

FIG. 5 is a circuit diagram of a pixel.

FIG. 6 is a circuit diagram of a pixel portion and an operation of the pixel portion at the time of repair.

FIG. 7 illustrates a structure of a driving circuit.

FIG. 8 illustrates a structure of a driving circuit.

FIG. 9 illustrates a structure of an EL element.

FIG. 10 illustrates a structure of an EL element.

FIG. 11 is an electronic apparatus having a light emitting device using the repair method of the present invention.

FIG. 12 is a cross-sectional view of an EL element having a defect, and FIG.
The figure which showed typically the flow of the electric current when the electric current of a forward bias flows into the L element.

FIG. 13 illustrates voltage-current characteristics of an EL element.

FIG. 14 is a graph of voltage-current characteristics when a reverse bias current is applied to an EL element.

FIG. 15 shows voltage-current characteristics of an EL element.

FIG. 16 is a cross-sectional view of a light-emitting device.

FIG. 17 is a cross-sectional view of a light-emitting device.

FIG. 18 is a cross-sectional view of a light-emitting device.

FIG. 19 illustrates a case where the repair method of the present invention is used for a passive light emitting device.

────────────────────────────────────────────────── ─── of the front page continued (51) Int.Cl. ⁷ identification mark FI theme Court Bu (reference) H05B 33/12 H05B 33/12 Z 33/14 33/14 a F -term (reference) 3K007 AB05 AB18 BA06 DA01 DB03 EB00 FA00 GA02 5C094 AA21 AA42 AA43 BA03 BA27 CA19 DA13 DB01 DB04 EA04 FA01 FB01 FB02 FB12 FB20 GA10 GB10 5G435 AA16 AA17 BB05 CC09 HH12 HH13 HH14 KK05

Claims (18)

[Claims] 1. A method for repairing a light emitting device in which a first voltage and a second voltage are sequentially applied to an EL element, wherein the first voltage and the second voltage are reverse biases having different heights from each other. A method for repairing a light emitting device, characterized in that: 2. A repair method for a light emitting device, wherein a voltage applied to an EL element is gradually changed from a first voltage to a second voltage, wherein the first voltage and the second voltage are mutually different. A method for repairing a light emitting device, wherein the voltages are reverse bias voltages having different heights. 3. A method for repairing a light emitting device including an EL element having an anode, an EL layer in contact with the anode, and a cathode in contact with the EL layer, wherein a first voltage is applied between the anode and the cathode. And a second voltage in order, wherein the first voltage and the second voltage are reverse-biased voltages having different heights from each other. 4. A method for repairing a light emitting device including an EL element having an anode, an EL layer in contact with the anode, and a cathode in contact with the EL layer, wherein a voltage applied between the anode and the cathode is A first voltage and a second voltage are gradually changed from a first voltage to a second voltage, and the first voltage and the second voltage are reverse bias voltages having different heights from each other. . 5. A method of repairing a light emitting device including an EL element having an anode, an EL layer in contact with the anode, and a cathode in contact with the EL layer, wherein a first voltage is applied between the anode and the cathode. And the second voltage are applied in order to insulate or increase the resistance of the portion where the reverse bias current flows between the anode and the cathode, and the first voltage and the second voltage are higher than each other. A method for repairing a light emitting device, wherein the voltages are reverse bias voltages of different magnitudes. 6. A method for repairing a light emitting device including an EL element having an anode, an EL layer in contact with the anode, and a cathode in contact with the EL layer, wherein a voltage applied between the anode and the cathode is By gradually changing the voltage from the first voltage to the second voltage, a portion where a reverse bias current flows between the anode and the cathode is insulated or made high in resistance, and the first voltage and the second Wherein the voltages are reverse bias voltages having different heights. 7. The device according to claim 1, wherein the first voltage and the second voltage are within ± 15% of an avalanche voltage of the EL element. How to repair a light emitting device. 8. A method for repairing a light emitting device, wherein a first voltage and a second voltage are sequentially applied to an EL element, wherein the first voltage is a ground voltage, and the second voltage is a reverse bias. A method for repairing a light emitting device, characterized in that: 9. A repair method for a light-emitting device, wherein a voltage applied to an EL element is gradually changed from a first voltage to a second voltage, wherein the first voltage and the second voltage are one of Is a ground voltage, and the other is a reverse bias voltage. 10. A method for repairing a light emitting device including an EL element having an anode, an EL layer in contact with the anode, and a cathode in contact with the EL layer, wherein a first voltage is applied between the anode and the cathode. And a second voltage are applied in order, wherein the first voltage is a ground voltage, and the second voltage is a reverse bias voltage. 11. A method for repairing a light emitting device including an EL element having an anode, an EL layer in contact with the anode, and a cathode in contact with the EL layer, wherein a voltage applied between the anode and the cathode is , Gradually changing from a first voltage to a second voltage, wherein one of the first voltage and the second voltage is a ground voltage, and the other is a reverse bias voltage. How to repair a light emitting device. 12. A method for repairing a light emitting device including an EL element having an anode, an EL layer in contact with the anode, and a cathode in contact with the EL layer, wherein a first voltage is applied between the anode and the cathode. And a second voltage are applied in order to insulate or increase the resistance of a portion through which a reverse bias current flows between the anode and the cathode, and the first voltage is a ground voltage; Wherein the voltage is a reverse bias voltage. 13. A method for repairing a light emitting device including an EL element having an anode, an EL layer in contact with the anode, and a cathode in contact with the EL layer, wherein a voltage applied between the anode and the cathode is By gradually changing the voltage from the first voltage to the second voltage, a portion where a reverse bias current flows between the anode and the cathode is insulated or made to have a high resistance, and the first voltage and the second voltage are changed. The method of repairing a light emitting device, wherein one of the voltages is a ground voltage and the other is a reverse bias voltage. 14. The method according to claim 8, wherein the reverse bias voltage falls within ± 15% of an avalanche voltage of the EL element. 15. A method for manufacturing a light emitting device including an EL element having an anode, an EL layer in contact with the anode, and a cathode in contact with the EL layer, the method comprising: forming the cathode; During the first
And a second voltage are applied in order, and the first voltage and the second voltage are reverse bias voltages having different heights from each other. 16. A method for manufacturing a light emitting device including an EL element having an anode, an EL layer in contact with the anode, and a cathode in contact with the EL layer, wherein the cathode and the cathode are formed after forming the cathode. Wherein the voltage applied during is gradually changed from a first voltage to a second voltage, wherein the first voltage and the second voltage are reverse bias voltages having different heights. Method for manufacturing a light emitting device. 17. A method for manufacturing a light emitting device including an EL element having an anode, an EL layer in contact with the anode, and a cathode in contact with the EL layer, the method comprising: forming the cathode; During the first
The voltage and the second voltage are sequentially applied to insulate or increase the resistance of a portion where a reverse bias current flows between the anode and the cathode. The first voltage and the second voltage are: A method for manufacturing a light-emitting device, wherein reverse bias voltages having different heights are used. 18. A method for manufacturing a light-emitting device including an EL element having an anode, an EL layer in contact with the anode, and a cathode in contact with the EL layer, the method comprising: forming the cathode; By gradually changing the voltage applied during the period from the first voltage to the second voltage, a portion through which a reverse bias current flows between the anode and the cathode is insulated or made to have a high resistance. The method for manufacturing a light-emitting device, wherein the first voltage and the second voltage are reverse bias voltages having different heights.