JP5127853B2 - Display device - Google Patents

Description

The present invention relates to a semiconductor display device using a protection circuit that can prevent dielectric breakdown of a semiconductor element.

How to suppress the charging phenomenon (charging) that leads to deterioration or dielectric breakdown of the semiconductor element is an important issue in the manufacturing process of the semiconductor device. In particular, with higher integration, not only the channel length is miniaturized, but the thickness of various insulating films such as gate insulating films is decreasing, and dielectric breakdown due to charging becomes a more serious problem. It has become.

Charging causes and environments are extremely complex and diverse. For this reason, it is necessary not only to investigate the cause and environment of charging, but also to devise measures to enhance the resistance to deterioration or dielectric breakdown due to charging in the configuration of the semiconductor device.
To prevent deterioration or dielectric breakdown due to charging, a diode (protective diode)
It is effective to secure a discharge path by a protection circuit using the. By securing the discharge path,
The charge accumulated in the insulating film can be prevented from being discharged in the vicinity of the semiconductor element, and thus the semiconductor element is deteriorated or destroyed by the energy of discharge (ESD: Elec
tro-Static Discharge) can be prevented.

In addition, by providing a protection circuit, even if noise is input to the wiring along with the signal and power supply voltage,
It is possible to prevent a subsequent circuit from malfunctioning due to the noise, and it is possible to prevent the semiconductor element from being deteriorated or destroyed by the noise.

By the way, in a semiconductor display device typified by a liquid crystal display device or a light emitting device, an active matrix type that can maintain a certain level of signal supply to a display element even after a video signal is input is increased in size and resolution of the panel. It is becoming the mainstream in the future. The configuration of the pixels in the active matrix semiconductor display device that has been specifically proposed differs somewhat depending on the manufacturer. Usually, at least a display element such as a light emitting element or a liquid crystal element and a TFT for controlling the operation of the display element are provided in each pixel.

Then, the semiconductor display device has a TF on the insulating film (first interlayer insulating film) covering the TFT.
A structure in which a display element is formed together with a wiring directly connected to the first terminal or the second terminal of T, and display on an insulating film (second interlayer insulating film) further covering the wiring There is a configuration in which elements are formed. In the case of a light-emitting device in which light from the light-emitting element is extracted from the side opposite to the TFT, the latter contributes to the entire pixel portion in the region contributing to light emission, so that the contrast is increased. Can be desirable.

However, the second interlayer insulating film that further covers the wiring is formed by using a coating method that can be easily flattened because the surface irregularities may affect the characteristics of the display element. This insulating coating film has a problem that it is easily charged during coating. However, a normal protection diode uses a TFT, and the TFT is formed in the same layer as a TFT constituting another circuit. Therefore, the electric charge charged in the insulating film formed in a layer above the insulating film covering the TFT used as the protective diode is not easily discharged through the discharge path secured by the protective circuit. . Therefore, there is a problem that dielectric breakdown is likely to occur due to the electric charge.

In view of the above problems, an object of the present invention is to provide a semiconductor display device using a protection circuit that can more effectively prevent dielectric breakdown.

In the present invention, the first interlayer insulating film is formed so as to cover the TFT used as the protective diode, and the wiring formed on the first interlayer insulating film is further covered so as to be the insulating coating film. In order to secure a path for discharging charges accumulated on the surface of the second interlayer insulating film when the second interlayer insulating film is formed, a wiring for connecting the TFT to another semiconductor element is provided. Then, it is formed so as to be in contact with the second interlayer insulating film. The TFT used as a protective diode is
This is a so-called diode-connected TFT in which either the first terminal or the second terminal is connected to the gate electrode.

Note that in this specification, one of the first terminal and the second terminal corresponds to a source region and the other corresponds to a drain region, and each time depending on the potential relationship between the first terminal and the second terminal. The source region or the drain region is determined. Specifically, in the case of an n-channel TFT, a terminal having a lower potential corresponds to a source region and a terminal having a higher potential corresponds to a drain region among the first terminal and the second terminal. In the case of a p-channel TFT, the higher terminal of the first terminal and the second terminal corresponds to the source region, and the lower terminal corresponds to the drain region.

In a diode-connected n-channel TFT, it is assumed that the first terminal and the gate electrode are connected. In this case, if the potential of the first terminal is higher than the potential of the second terminal,
The first terminal corresponds to the drain region, the second terminal corresponds to the source region, and the n-channel TFT is turned on. Therefore, a forward current from the first terminal to the second terminal is obtained. On the other hand, when the potential of the first terminal is lower than the potential of the second terminal, the first terminal corresponds to the source region and the second terminal corresponds to the drain region, and the n-channel TFT is turned off.

Further, it is assumed that the first terminal and the gate electrode are connected in a diode-connected p-channel TFT. In this case, when the potential of the first terminal is higher than the potential of the second terminal, the first terminal corresponds to the source region and the second terminal corresponds to the drain region, and the p-channel TFT
Turn off. Conversely, when the potential of the first terminal is lower than the potential of the second terminal, the first terminal corresponds to the drain region and the second terminal corresponds to the source region, and the p-channel TFT is turned on. Therefore, a forward current from the second terminal to the second terminal is obtained.

Specifically, in the semiconductor display device of the present invention, a TFT used as a protective diode is formed on an insulating surface, a first interlayer insulating film is formed to cover the TFT, and the first interlayer insulating film is formed. A second interlayer insulating film is formed so as to cover either one of the first terminal or the second terminal of the TFT and the gate electrode, and the first wiring is connected. The first wiring is formed so as to be in contact with the first interlayer insulating film, and the second wiring is formed on the second interlayer insulating film. It is formed so that it may touch.

In the semiconductor display device of the present invention, a first TFT for supplying a signal to a display element, a second TFT used as a protective diode, and a third TFT are formed on an insulating surface, and the first TFT A first interlayer insulating film is formed to cover the TFT, the second TFT, and the third TFT, and a second interlayer insulating film is formed to cover the first interlayer insulating film, A display element is formed on the second interlayer insulating film, and the first terminal or the second terminal of the first TFT and the display element are connected by a first wiring and a second wiring. The first terminal of the second TFT and the gate electrode are connected by a third wiring, and the first terminal or the second terminal of the third TFT and the gate electrode are connected to each other. Are connected by a fourth wiring, and the second TF The second terminal is connected to the fourth wiring by a fifth wiring and the sixth wiring, and the first wiring, the third wiring, the fourth wiring, and the fifth wiring are connected to the fourth wiring. Is formed so as to be in contact with the first interlayer insulating film, and the second wiring
The sixth wiring and the sixth wiring are formed so as to be in contact with the second interlayer insulating film.

According to another configuration of the semiconductor display device of the present invention, a first T for supplying a signal to the display element is provided.
An FT, a second TFT and a third TFT used as protective diodes are formed on an insulating surface, covering the first TFT, the second TFT, and the third TFT, and a first interlayer An insulating film is formed, a second interlayer insulating film is formed to cover the first interlayer insulating film, a display element is formed on the second interlayer insulating film, and the first interlayer insulating film is formed. The first terminal or the second terminal of the TFT and the display element are connected by a first wiring and a second wiring, and the first terminal of the second TFT and the gate electrode are Connected by a third wiring, and the second terminal of the second TFT, the first terminal or the second terminal of the third TFT, and the gate electrode are connected by a fourth wiring. And the fourth wiring is connected to the fifth wiring, The first wiring, the third wiring, and the fourth wiring are formed to be in contact with the first interlayer insulating film, and the second wiring and the fifth wiring are It is formed so as to be in contact with the second interlayer insulating film.

According to the present invention, the first interlayer insulating film is formed so as to cover the two TFTs used as the protective diode and further covers the wiring formed on the first interlayer insulating film. When the insulating film is formed, a path for discharging the charge accumulated on the surface of the second interlayer insulating film can be secured. Therefore, the phenomenon that the semiconductor element is destroyed can be prevented by discharging the electric charge charged on the surface of the second interlayer insulating film.

The figure which shows the circuit diagram and sectional drawing of the protection circuit of this invention. The figure which shows the circuit diagram of the protection circuit of this invention. The top view of the board | substrate with which the protection circuit of this invention was provided. The circuit diagram of the protection circuit of this invention. 8A and 8B illustrate a method for manufacturing a semiconductor display device of the present invention. 8A and 8B illustrate a method for manufacturing a semiconductor display device of the present invention. 8A and 8B illustrate a method for manufacturing a semiconductor display device of the present invention. FIG. 10 shows a positional relationship between a signal line driver circuit and a protection circuit included in a semiconductor display device of the present invention. 4 is an equivalent circuit diagram of a signal line driver circuit and a protection circuit included in the semiconductor display device of the present invention. FIG. 4 is an equivalent circuit diagram of a scanning line driving circuit and a protection circuit included in the semiconductor display device of the present invention. FIG. 4 is an equivalent circuit diagram of a pixel included in the light-emitting device of the present invention. FIG. 4 is an equivalent circuit diagram of a pixel included in the light-emitting device of the present invention. FIG. 4 is a top view of a pixel included in a light-emitting device of the present invention. FIG. 2A and 2B are a top view and a cross-sectional view of a light-emitting device of the present invention. FIG. 14 is a diagram of an electronic device using the semiconductor display device of the invention.

A configuration of a protection circuit used in the semiconductor display device of the present invention will be described with reference to FIG. In the present invention, the protection circuit is provided with a protection diode in the discharge path. Figure 1
A) corresponds to a circuit diagram showing one embodiment of the protection circuit of the present invention, and is connected in diode connection at least one each for a path where positive charges are discharged and a path where negative charges are discharged. TFTs 101 and 102 are provided.

Specifically, the TFTs 101 and 102 each have a first terminal and a gate electrode connected to each other. The TFT 101 is supplied with the potential Vdd at the first terminal, and the TFT 102 is supplied with the potential Vss at the second terminal. Note that in this specification, potential Vss <potential Vdd. Further, the second terminal of the TFT 101 and the first terminal of the TFT 102 are electrically connected to each other, and are further electrically connected together to a semiconductor element to be protected.
Note that in FIG. 1A, it is assumed that the second terminal of the TFT 101 and the first terminal of the TFT 102 are electrically connected to the wiring 103.

Note that FIG. 1A illustrates an example in which both the TFTs 101 and 102 are p-channel TFTs, but either one or both of the TFTs 101 and 102 may be n-channel TFTs. Even when an n-channel TFT is used, the first terminal and the gate electrode are connected.

The protection circuit according to the present invention is characterized by wiring for electrically connecting TFTs used as protection diodes, specifically, its layout. In FIG. 1B, TFT1
A cross-sectional view of 01 and the TFT 102 is shown as an example.

The TFT 101 includes an island-shaped semiconductor film 104, a gate insulating film 105 in contact with the island-shaped semiconductor film 104, and a gate electrode 106 overlapping the island-shaped semiconductor film 104 with the gate insulating film 105 interposed therebetween. have. The island-shaped semiconductor film 104 includes a first terminal 108 and a second terminal 109 which correspond to a channel formation region 107 overlapping with the gate electrode 106 and a source region or a drain region sandwiching the channel formation region 107 therebetween. And have.

The TFT 102 includes an island-shaped semiconductor film 114, a gate insulating film 105 in contact with the island-shaped semiconductor film 114, and a gate electrode 116 that overlaps the island-shaped semiconductor film 114 with the gate insulating film 105 interposed therebetween. have. The island-shaped semiconductor film 114 includes a channel formation region 117 that overlaps with the gate electrode 116 and a source region or a drain region that corresponds to a source region or a drain region that sandwich the channel formation region 117 therebetween. And have.

The TFT 101 and the TFT 102 are covered with a first interlayer insulating film 120 having one or a plurality of insulating films. Wirings 121 to 124 connected to the TFT 101 and the TFT 102 through contact holes formed in the first interlayer insulating film 120 are formed so as to be in contact with the first interlayer insulating film 120.

Specifically, the wiring 121 is connected to the first terminal 108 and the gate electrode 106 of the TFT 101, and the wiring 122 is connected to the second terminal 109 of the TFT 101. The wiring 123 is connected to the first terminal 118 and the gate electrode 116 of the TFT 102, and the wiring 124 is connected to the second terminal 119 of the TFT 102.

In FIG. 1B, each of the wirings 121 to 124 is formed of a single wiring.
The present invention is not limited to this configuration. Each of the wirings 121 to 124 may include a plurality of electrically connected wirings.

A second interlayer insulating film 125 is formed on the first interlayer insulating film 120 so as to cover the wirings 121 to 124. Since the second interlayer insulating film 125 needs to have a display element formed thereon, it is desirable that the surface be flattened, and it is preferable that the second interlayer insulating film 125 be formed by a coating method. Note that the second interlayer insulating film 125 may be formed of a single insulating film or a plurality of insulating films. In any case, it is preferable that at least one insulating film is formed by a coating method.

Then, the wirings 122, 1 are connected through the contact holes formed in the second interlayer insulating film 125.
A wiring 126 connected to the second interlayer insulating film 125 is formed so as to be in contact with the second interlayer insulating film 125. A second terminal 109 of the TFT 101 is connected to the TFT by wirings 122, 123, and 126.
The first terminal 102 and the gate electrode 116 are electrically connected. And wiring 12
2, 123 and 126 are electrically connected to the wiring 103 shown in FIG.

Note that in FIG. 1B, the wiring 126 is formed using a single wiring; however, the present invention is not limited to this structure. The wiring 126 may include a plurality of electrically connected wirings.

In the present invention, the wiring 122 and the wiring 123 are electrically connected through the wiring 126, but the present invention is not limited to this structure. For example, as shown in FIG.
The second terminal 109 of 01, the first terminal 118 of the TFT 102, and the gate electrode 116 may be connected by a wiring 127 formed so as to be in contact with the first interlayer insulating film 120. The wiring 127 may be a single wiring or a plurality of electrically connected wirings. The wiring 127 is also connected to the wiring 126.

In the case of FIG. 1B, the length of the wiring directly connected to the TFT can be shortened as compared with the case of FIG. 1C, so that dielectric breakdown occurs in the TFTs 101 and 102 due to the antenna effect. Can be suppressed. In the case of FIG. 1C, since the discharge path is already secured from the protection circuit before the second interlayer insulating film 125 is formed, ESD due to charging can be prevented more reliably.

1B and 1C, for example, when a positive charge is charged on the surface of the second interlayer insulating film 125 and a potential Vdd ′ higher than the potential Vdd is applied to the wiring 126, FIG. 2
As shown in (A), the TFT 101 is turned on and the TFT 102 is turned off. Therefore, the positive charge is discharged through the TFT 101. Further, in FIGS. 1B and 1C, for example, when a negative charge is charged on the surface of the second interlayer insulating film 125 and a potential Vss ′ lower than the potential Vss is applied to the wiring 126, FIG. 2B, the TFT 101 is turned off and the TFT 102 is turned on. Therefore, the negative charge is discharged through the TFT 102.

Therefore, in any case, since the potential higher than Vdd or the potential lower than Vss is not applied to the wiring 103, damage due to charging of the semiconductor element electrically connected to the wiring 103 is avoided. be able to.

The protection circuit is particularly effective in preventing the semiconductor element from being deteriorated or destroyed by charging that occurs when the second interlayer insulating film is formed by a coating method. However, the semiconductor display device of the present invention is not limited to the second interlayer insulating film being a coating film. The causes and environments of charging are extremely complicated and varied. The possibility of charging cannot be denied except when the second interlayer insulating film is formed by a coating method. Therefore, according to the present invention, the second interlayer insulating film is formed by a film forming method other than the coating method, for example, vapor deposition method, sputtering method, C
Even when a film is formed by the VD method or the like, it is effective in preventing ESD.

Next, the structure of the semiconductor display device of the present invention will be described with reference to FIG. FIG. 3 is a top view of the substrate 130 included in the semiconductor display device. The pixel portion 131 and the pixel portion 1 are formed over the substrate 130.
A scanning line driving circuit 132 that selects pixels included in the pixel 31 and a signal line driving circuit 133 that supplies a video signal to the selected pixels are formed. Reference numeral 134 corresponds to an input terminal for supplying a signal or a power supply potential to various circuits formed on the substrate 130.

Reference numerals 135 to 137 correspond to protection circuits. Various circuits formed on the substrate 130 are connected by wiring, and the wiring is connected to the protection circuits 135 to 137.

Specifically, the input terminal 134 and the signal line driver circuit 133 are connected by a wiring 140, and the protection circuit 135 is connected to the wiring 140. Various semiconductor elements included in the signal line driver circuit 133 can be protected by the protection circuit 135.

In addition, the signal line driver circuit 133 and the pixel portion 131 are connected by a signal line 141, and the protection circuit 136 is connected to the signal line 141. The protection circuit 136 can protect various semiconductor elements included in the signal line driver circuit 133 and the pixel portion 131. Note that the protection circuit 136 may be connected to the signal line 141. Therefore, for example, as shown in FIG. 3, the protection circuit 136 may be provided between the signal line driver circuit 133 and the pixel portion 131, or opposite to the signal line driver circuit 133 with the pixel portion 131 interposed therebetween. It may be provided on the side. Although not shown, the protection circuit 136 includes a signal line driving circuit 133 and an input terminal 134.
It may be provided between.

Further, the scanning line driving circuit 132 and the pixel portion 131 are connected by a scanning line 142, and the protection circuit 137 is connected to the scanning line 142. The protection circuit 137 can protect various semiconductor elements included in the scan line driver circuit 132 and the pixel portion 131. Note that the protection circuit 137 may be connected to the scanning line 142. Therefore, the protection circuit 137
For example, as shown in FIG. 3, it may be provided between the scanning line driving circuit 132 and the pixel portion 131, or provided on the opposite side of the scanning line driving circuit 132 with the pixel portion 131 interposed therebetween. Also good. Although not shown, the protection circuit 137 includes a scanning line driving circuit 132 and an input terminal 13.
4 may be provided.

Note that it is not necessary to provide all of the protection circuits 135 to 137, and any one or a plurality of them may be provided.

In the present invention, the protection circuit can reduce not only discharge of electric charges charged in the second interlayer insulating film but also noise input to the wiring together with the signal or the power supply voltage, and the semiconductor element deteriorates due to the noise. Or being destroyed.

In FIG. 3, the signal line driver circuit 133 and the scan line driver circuit 132 are formed over the same substrate 130 as the pixel portion 131; however, the present invention is not limited to this structure. For example, the pixel portion 131
In the case where an amorphous semiconductor or a microcrystalline semiconductor is used as the semiconductor element forming the semiconductor device, a signal line driver circuit 133 and a scan line driver circuit 132 which are separately formed are mounted on the substrate 130 by a known method such as a COG method or a TAB method. May be. In this case, the protection circuit is connected to a wiring that connects the input terminal and the pixel portion. In the case where a microcrystalline semiconductor is used as an element included in the pixel portion 131, the scan line driver circuit and the pixel portion may be formed using a microcrystalline semiconductor over the same substrate, and the signal line driver circuit may be mounted. . Further, a part of the scan line driver circuit or a part of the signal line driver circuit is formed over the same substrate together with the pixel portion, and the other part of the scan line driver circuit or the other part of the signal line driver circuit is mounted. Anyway. In other words, since there are various forms of the drive circuit, the number and location of the protection circuits are determined in accordance with the form.

  Next, a specific example of the protection circuit used in the present invention will be described with reference to FIG.

The protection circuit illustrated in FIG. 4A includes protection diodes 401 to 404 using a plurality of TFTs. The protection diode 401 includes two p-channel TFTs 40 connected in series.
1a and 401b. Then, two p-channel TFTs 40 connected in series
One ends of 1a and 401b are connected to gate electrodes of two p-channel TFTs 401a and 401b. The other protection diodes 402 to 404 each have a plurality of TFTs connected in series, like the protection diode 401, and one end of the plurality of TFTs connected in series is the gate of the plurality of TFTs. It is connected to the electrode.

Note that in the present invention, the number and polarity of TFTs included in the protection diodes 401 to 404 are not limited to the structure illustrated in FIG.

The protection diodes 401 to 404 are connected in series in order, and a node between the protection diode 402 and the protection diode 403 is connected to the wiring 405.
Note that the wiring 405 is assumed to be connected to a semiconductor element to be protected. Note that the node connected to the wiring 405 is not limited to the node between the protection diode 402 and the protection diode 403, and any of the plurality of nodes between the protection diodes 401 to 404 connected in series may be used. good.

The potential Vss is applied to one end of the protection diodes 401 to 404 connected in series.
The other end is given a potential Vdd. And each protection diode 401-404,
They are connected in such a direction as to apply a reverse bias voltage.

The protection circuit illustrated in FIG. 4B includes protection diodes 410 and 411, and capacitor elements 412 and 41.
3 and a resistance element 414 is provided. The resistance element 414 is a two-terminal resistor, and has a wiring 41 at one end.
5 is supplied with the potential Vin, and the other end is supplied with the potential Vss. The resistance element 414 is provided to drop the potential of the wiring 415 to the potential Vss when the potential Vin is no longer applied, and the resistance value is set to be sufficiently larger than the wiring resistance of the wiring 414. . Each of the protection diodes 410 and 411 uses a diode-connected p-channel TFT.

When the potential Vin is higher than the potential Vdd, the p-channel TFT included in the protection diode 410 is on and the protection diode is 411 depending on the voltage between the gate electrode and the source region.
The p-channel TFT included in is turned off. Then, the potential Vdd is supplied to the wiring 415 through the protection diode 410. Therefore, due to noise or the like, the potential Vin becomes the potential V
Even when the potential is higher than dd, the potential applied to the wiring 415 does not become higher than the potential Vdd. On the other hand, when the potential Vin is lower than the potential Vss, the p-channel TFT of the protection diode 410 is turned off and the p-channel TFT of the protection diode 411 is turned on by the voltage between the gate electrode and the source region. . Then, the potential Vss is given to the wiring. Therefore, even if the potential Vin becomes lower than the potential Vss due to noise or the like,
The potential applied to the wiring 415 is never lower than the potential Vss. Further, the capacitor elements 412 and 413 can damp pulsed noise included in the input potential Vin, and can reduce a sudden change in potential due to noise to some extent.

With the arrangement of the protection circuit having the above structure, the potential of the wiring is kept between the potential Vss and the potential Vdd, and the subsequent circuit can be protected from application of an abnormally high or low potential outside this range. Furthermore, by providing a protective circuit at the input terminal to which a signal is input, the potential of all wirings to which the signal is applied is kept constant (here, the potential Vss) when no signal is input. Can do. In other words, when a signal is not input, it also has a function as a short ring that can short-circuit the wires. Therefore, electrostatic breakdown due to a potential difference between wirings can be prevented. When a signal is input, the resistance element 414
Since the resistance value is sufficiently large, a signal applied to the wiring is not pulled to the potential Vss.

The protection circuit shown in FIG. 4C is an equivalent circuit diagram in which the protection diodes 410 and 411 are replaced with two p-channel TFTs, respectively.

Note that the protection circuits illustrated in FIGS. 4B and 4C use p-channel TFTs that are diode-connected as protection diodes, but the present invention is not limited to this structure. A diode-connected n-channel TFT may be used as the protective diode.

4D includes protective diodes 420 to 427 and a resistance element 42.
8. The resistance element 428 is connected in series with the wiring 429. Each protection diode 420 to 423 uses a diode-connected n-channel TFT, and each protection diode 424 to 427 is a diode-connected p-channel TF.
T is used.

The protection diodes 420 and 421 are connected in series, one end is supplied with the potential Vss, and the other end is connected to the wiring 429. The protective diodes 422 and 423 are connected in series, one end is supplied with the potential Vdd, and the other end is connected to the wiring 429. The protective diodes 424 and 425 are connected in series, one end is supplied with the potential Vss, and the other end is connected to the wiring 429. The protection diodes 426 and 427 are connected in series, one end is supplied with the potential Vdd, and the other end is connected to the wiring 429.

4E includes resistance elements 430 and 431 and a protection diode 43.
2. In FIG. 4E, a diode-connected n-channel TFT is used as the protective diode 432; however, the present invention is not limited to this structure. A diode-connected p-channel TFT may be used, or a plurality of diode-connected TFTs may be used. The resistance elements 430 and 431 and the protection diode 432 are connected to the wiring 433 in series.

The resistance elements 430 and 431 can alleviate rapid fluctuations in the potential of the wiring 433 and prevent deterioration or destruction of the semiconductor element. In addition, the protection diode 432 can prevent a reverse bias current from flowing through the wiring 433 due to potential fluctuation.

Note that in the case where only the resistance element is connected in series to the wiring, a rapid change in the potential of the wiring can be reduced and deterioration or destruction of the semiconductor element can be prevented. Further, when only the protective diode is connected in series to the wiring, it is possible to prevent a reverse current from flowing through the wiring due to potential fluctuation.

Next, a specific method for manufacturing a light-emitting device, which corresponds to one embodiment of the semiconductor display device of the present invention, will be described. Note that in this embodiment, an example in which a TFT used for a protection circuit and a TFT for controlling supply of current to a light-emitting element are formed over the same substrate will be described.

First, as shown in FIG. 5A, a base film 202 is formed over a substrate 201. Examples of the substrate 201 include glass substrates such as barium borosilicate glass and alumino borosilicate glass,
A quartz substrate, a ceramic substrate, or the like can be used. Alternatively, a metal substrate including a SUS substrate or a silicon substrate with an insulating film formed on the surface thereof may be used. A substrate made of a synthetic resin having flexibility such as plastic generally tends to have a lower heat resistant temperature than the above substrate, but can be used as long as it can withstand the processing temperature in the manufacturing process. .

The base film 202 is provided to prevent alkali metal such as Na or alkaline earth metal contained in the substrate 201 from diffusing into the semiconductor film and adversely affecting the characteristics of the semiconductor element such as TFT. Therefore, the insulating film is formed using an insulating film such as silicon oxide, silicon nitride, or silicon nitride oxide that can suppress diffusion of alkali metal or alkaline earth metal into the semiconductor film. In this example,
A silicon nitride oxide film is formed to 10 to 400 nm (preferably 50 to 300 nm) by plasma CVD.
nm).

Note that the base film 202 may be a single layer or a stack of a plurality of insulating films. In the case of using a substrate containing an alkali metal or an alkaline earth metal, such as a glass substrate, a SUS substrate, or a plastic substrate, it is effective to provide a base film from the viewpoint of preventing impurity diffusion. However, when diffusion of impurities does not cause any problem, such as a quartz substrate, it is not necessarily provided.

Next, island-shaped semiconductor films 203 to 205 used as active layers are formed over the base film 202. The film thickness of the island-shaped semiconductor films 203 to 205 is 25 to 100 nm (preferably 30 to 60 nm).
). Note that the island-shaped semiconductor films 203 to 205 may be an amorphous semiconductor, a semi-amorphous semiconductor (microcrystalline semiconductor), or a polycrystalline semiconductor. As the semiconductor, not only silicon but also silicon germanium can be used. When silicon germanium is used, the concentration of germanium is preferably about 0.01 to 4.5 atomic%.

In the case of using a polycrystalline semiconductor, an amorphous semiconductor is first formed, and the amorphous semiconductor may be crystallized using a known crystallization method. Known crystallization methods include crystallization by heating with a heater, crystallization by laser light irradiation, crystallization using a catalytic metal, and crystallization using infrared light. The method of performing etc. are mentioned.

For example, when crystallization is performed using laser light, a pulsed or continuous wave excimer laser, YAG laser, YVO ₄ laser, or the like may be used. For example, when a YAG laser is used, it is desirable to use a second harmonic wavelength that is easily absorbed by the semiconductor film. The oscillation frequency 30～300KHz, the energy density was 300~600mJ / cm ² (typically 350~500mJ / cm ^2), it may be set the scanning speed to be irradiated by several shots to any point.

Next, a TFT is formed using the island-shaped semiconductor films 203 to 205. Note that in this embodiment, as shown in FIG. 5B, a top gate type T is formed using island-shaped semiconductor films 203 to 205.
FTs 206 to 208 are formed.

Specifically, a gate insulating film 209 is formed so as to cover the island-shaped semiconductor films 203 to 205. Then, a conductive film is formed over the gate insulating film 209 and patterned to form the gate electrodes 210 to 212. Then, using the gate electrodes 210 to 212 or a resist as a mask, an impurity imparting n-type or p-type is added to the island-shaped semiconductor films 203 to 205, so that a source region, a drain region, an LDD region, and the like are formed. Form. Here, a case where all of the TFTs 206 to 208 are p-type is shown.

Note that for the gate insulating film 209, for example, silicon oxide, silicon nitride, silicon nitride oxide, or the like can be used. As a film formation method, a plasma CVD method, a sputtering method, or the like can be used. For example, when a gate insulating film using silicon oxide is formed by a plasma CVD method, TE
Using a mixed gas of OS (Tetraethyl Orthosilicate) and O ₂ , the reaction pressure is 40 Pa, the substrate temperature is 300 to 400 ° C., and the high frequency (13.56 MHz) power density is 0.5 to 0.8 W / cm ² .

Aluminum nitride can be used for the gate insulating film 209. Aluminum nitride has a relatively high thermal conductivity and can efficiently dissipate heat generated in the TFT.
In addition, after forming silicon oxide or silicon oxynitride which does not contain aluminum, a laminate of aluminum nitride may be used as the gate insulating film.

Through the above series of steps, the TFTs 206 and 207 used for the protective diode and the TFT 208 for controlling the current supplied to the light emitting element can be formed. Note that a method for manufacturing a TFT is not limited to the above-described steps. A gate electrode or a wiring may be manufactured by a droplet discharge method.

Next, a passivation film 213 corresponding to a part of the first interlayer insulating film is formed so as to cover the TFTs 206 to 208. As the passivation film 213, an insulating film such as silicon oxide containing silicon, silicon nitride, or silicon oxynitride can be used, and the thickness thereof is 100 to 200 nm.
To the extent.

Next, heat treatment is performed to activate the impurity element added to the island-shaped semiconductor films 203 to 205. In this step, a thermal annealing method using a furnace annealing furnace, a laser annealing method, or a rapid thermal annealing method (RTA method) can be used. For example, when activation is performed by thermal annealing, it is performed at 400 to 700 ° C. (preferably 500 to 600 ° C.) in a nitrogen atmosphere having an oxygen concentration of 1 ppm or less, preferably 0.1 ppm or less. Further, a heat treatment is performed at 300 to 450 ° C. for 1 to 12 hours in an atmosphere containing 3 to 100% hydrogen to perform a step of hydrogenating the island-shaped semiconductor film. This step is performed for the purpose of terminating the dangling bonds with thermally excited hydrogen. As another means of hydrogenation, plasma hydrogenation (using hydrogen excited by plasma) may be performed. The activation process may be performed before the passivation film 213 is formed.

Next, as shown in FIG. 5C, a first insulating film 214 is formed so as to cover the passivation film 213. As the first insulating film 214, an organic resin film, an inorganic insulating film, an insulating film including a Si—O bond and a Si—CH _X bond formed using a siloxane-based material as a starting material, or the like can be used. In this embodiment, a film in which the first insulating film 214 and the passivation film 213 are stacked corresponds to the first interlayer insulating film 215. Note that the first interlayer insulating film 215 includes:
A single-layer insulating film may be formed, or a plurality of insulating films may be formed.

Next, the gate insulating film 209 and the first interlayer insulating film 215 are etched to form contact holes. Then, the island-shaped semiconductor film 2 is in contact with the first interlayer insulating film 215.
Wirings 216 to 221 connected to 03 to 205 and the gate electrodes 210 and 211 are formed.

Note that the TFT 206 includes a first terminal 223 corresponding to a source region or a drain region,
The gate electrode 210 is connected to the gate electrode 216. A second terminal 225 corresponding to the source region or the drain region of the TFT 206 is connected to the wiring 217.
In the TFT 207, a first terminal 226 corresponding to a source region or a drain region and a gate electrode 211 are connected by a wiring 218. A second terminal 228 corresponding to the source region or the drain region of the TFT 207 is connected to the wiring 219. TFT
Reference numeral 208 denotes a first terminal 229 corresponding to a source region or a drain region, and a gate electrode 2.
12 are connected by a wiring 220. A second terminal 231 corresponding to the source region or the drain region of the TFT 208 is connected to the wiring 221.

Next, as illustrated in FIG. 6A, a second insulating film 233 and a third insulating film 234 are sequentially formed so as to cover the wirings 216 to 221 and to be in contact with the first insulating film 214. . A film in which the second insulating film 233 and the third insulating film 234 are stacked corresponds to the second interlayer insulating film 235. Note that the second interlayer insulating film 235 may be formed of a single-layer insulating film or a plurality of insulating films.

As the second insulating film 233, an organic resin film, an inorganic insulating film, an insulating film including a Si—O bond and a Si—CH _X bond formed using a siloxane-based material as a starting material, or the like can be used. In this embodiment, an insulating film formed using a siloxane-based material is used for the coating method. As the third insulating film 234, a film that hardly transmits a substance that causes deterioration of the light-emitting element such as moisture or oxygen as compared with other insulating films is used. Typically, a silicon nitride film formed by RF sputtering is used, but diamond-like carbon (DLC) is also used.
) Film, an aluminum nitride film, or the like.

Next, as shown in FIG. 6B, the second interlayer insulating film 235 is etched to form contact holes. Then, wirings 236, 237 connected to the wirings 217, 218, 221 are provided.
Is formed in contact with the second interlayer insulating film 235. Specifically, the wiring 236 is the wiring 2.
17 and 218, and the wiring 237 is connected to the wiring 221.

Next, as illustrated in FIG. 7A, an anode 240 is formed so as to cover the wirings 236 and 237 and to be in contact with the third insulating film 234. The anode 240 is connected to the wiring 237. As the anode 240, for example, a single layer film made of one or a plurality of TiN, ZrN, Ti, W, Ni, Pt, Cr, Ag, etc., a laminate of titanium nitride and a film mainly composed of aluminum, titanium nitride A three-layer structure of a film, a film containing aluminum as its main component, and a titanium nitride film can be used. In this embodiment, the anode 240 is formed using TiN.

In this embodiment, the case where light is extracted from the cathode side is described.
You may make it take out light from the side. In this case, the anode 240 is made of indium tin oxide (
Other light-transmitting oxide conductive materials such as ITO), zinc oxide (ZnO), indium zinc oxide (IZO), and zinc oxide added with gallium (GZO) can be used. ITO
Further, indium tin oxide containing silicon oxide (hereinafter referred to as ITSO) or indium oxide containing silicon oxide mixed with 2 to 20% zinc oxide (ZnO) may be used.

Next, a partition wall 241 is formed over the third insulating film 234. As the partition wall 241, an Si—O bond and Si—C formed using an organic resin film, an inorganic insulating film, and a siloxane-based material as a starting material.
An insulating film containing an H _X bond can be used. The partition wall 241 covers an end portion of the anode 240 and has an opening in a region overlapping with the anode 240. It is preferable that the end portion of the opening of the partition wall 241 is rounded so that there is no hole in the electroluminescent layer to be formed later at the end portion. Specifically, it is desirable that the curvature radius of the curve drawn by the cross section of the partition wall 241 in the opening is about 0.2 to 2 μm.

FIG. 7A illustrates an example in which a positive photosensitive acrylic resin is used as the partition wall 241. The photosensitive organic resin includes a positive type in which a portion exposed to energy rays such as light, electrons, and ions is removed, and a negative type in which the exposed portion remains. In the present invention, a negative organic resin film may be used. Alternatively, the partition 241 may be formed using photosensitive polyimide.
In the case where the partition wall 241 is formed using negative acrylic, the end of the opening has an S-shaped cross-sectional shape. At this time, the radius of curvature at the upper and lower ends of the opening is 0.2-2 μm.
m is desirable.

With the above structure, coverage of an electroluminescent layer and a cathode to be formed later can be improved, and a short circuit between the anode 240 and the cathode in a hole formed in the electroluminescent layer can be prevented. Further, by relaxing the stress of the electroluminescent layer, a defect called “shrink” in which the light emitting region decreases can be reduced, and reliability can be improved.

Before forming the electroluminescent layer, the surface of the anode 240 may be polished by CMP or wiping with a polyvinyl alcohol-based porous body so that the surface of the anode 240 is planarized.

Further, before forming the electroluminescent layer, in order to remove moisture, oxygen, and the like adsorbed on the partition wall 241 and the anode 240, heat treatment is performed in an air atmosphere or heat treatment (vacuum baking) in a vacuum atmosphere.
May be performed. Specifically, the temperature of the substrate is 200 to 450 ° C., preferably 250 to
Heat treatment is performed in a vacuum atmosphere at 300 ° C. for about 0.5 to 20 hours. Desirably 3x
10 ⁻⁷ Torr or less, and 3 × 10 ⁻⁸ Torr or less is most preferable if possible. In the case where an electroluminescent layer is formed after heat treatment in a vacuum atmosphere, reliability can be further improved by placing the substrate in a vacuum atmosphere until just before the electroluminescent layer is formed. it can. Further, the anode 240 may be irradiated with ultraviolet rays before or after vacuum baking.

An electrode formed in contact with the second interlayer insulating film 235 (in this embodiment, the anode 24
0) is formed of a light-transmitting oxide conductive material and a conductive film containing silicon oxide like ITSO, and the second
Of the interlayer insulating film 235, the insulating film (the third insulating film 234 in this embodiment) in contact with the electrode is formed of silicon nitride, so that the anode 240 and the third insulating film 234 are formed of other materials. The luminance of the light emitting element can be increased as compared with the combination. In this case, the above-described vacuum baking is particularly effective because moisture easily adheres to silicon oxide contained in the anode 240.

Next, as illustrated in FIG. 7B, an electroluminescent layer 242 is formed over the anode 240. The electroluminescent layer 242 includes one or a plurality of layers, and each layer may contain an inorganic material as well as an organic material. The electroluminescent layer 242 is preferably provided with an electron injection layer when the work function of the material used for the cathode is not sufficiently small.

Next, a cathode 243 is formed so as to cover the electroluminescent layer 242. The anode 240, the electroluminescent layer 242, and the cathode 243 overlap at the opening of the partition wall 241, and the overlapping portion corresponds to the light emitting element 244.

The cathode 243 has translucency. Specifically, indium tin oxide (ITO), zinc oxide (ZnO), indium zinc oxide (IZO), zinc oxide (GZ added with gallium)
Other light-transmitting oxide conductive materials such as O) can be used. Indium tin oxide containing ITO and silicon oxide (hereinafter referred to as ITSO) or indium oxide containing silicon oxide mixed with 2 to 20% zinc oxide (ZnO) may be used. In this case, it is desirable to provide an electron injection layer in the electroluminescent layer 242 so as to be in contact with the cathode 243.

Further, a metal, an alloy, an electrically conductive compound, a mixture thereof, or the like with a low work function can be formed to have a thickness enough to transmit light and used as the cathode 243. Specifically, in addition to alkaline metals such as Li and Cs, alkaline earth metals such as Mg, Ca and Sr, and alloys containing these (Mg: Ag, Al: Li, etc.), rare earths such as Yb and Er The cathode 243 can be formed with a film thickness of about 5 nm to 30 nm using metal. In the case of providing an electron injection layer, another conductive layer such as Al is formed with a thickness enough to transmit light, and the cathode 243 is formed.
Can also be used. Note that in the case where the cathode 243 is formed with a thickness enough to transmit light, a light-transmitting conductive layer is formed using a light-transmitting oxide conductive material so as to be in contact with or under the cathode 243, and The sheet resistance of the cathode may be suppressed. Note that in the case where light is reflected on the cathode 243 side and light is desired to be extracted only from the anode 240 side, the cathode 243 may be formed with a thickness enough to reflect the light.

Note that after the light-emitting element 244 is formed, a protective film may be formed over the cathode 243. Like the third insulating film 234, the protective film is a film that is less likely to transmit a substance that causes deterioration of the light-emitting element such as moisture and oxygen than other insulating films. Typically, for example, DLC
It is desirable to use a film, a carbon nitride film, a silicon nitride film formed by RF sputtering, or the like. In addition, the above-described film that hardly transmits a substance such as moisture or oxygen and a film that easily allows a substance such as moisture or oxygen to pass through can be stacked to be used as a protective film.

Note that FIG. 7B illustrates an example in which the anode is formed closer to the substrate than the cathode, but the present invention is not limited to this structure. The cathode may be formed closer to the substrate than the anode.

Actually, when completed up to FIG. 7B, a protective film (laminate film, ultraviolet curable resin film, etc.) or a translucent cover material with high air tightness and low outgassing so as not to be exposed to the outside air. It is preferable to package (enclose). At that time, if the inside of the cover material is made an inert atmosphere or a hygroscopic material (for example, barium oxide) is arranged inside, the reliability of the light emitting element is improved.

Note that the method for manufacturing a light-emitting device of the present invention is not necessarily limited to the above-described embodiment. further,
The semiconductor display device of the present invention includes not only a light emitting device but also a liquid crystal display device in its category. The above-described embodiments are merely specific descriptions of one aspect of the present invention, and the present invention is not limited to the above-described embodiments, and various modifications based on the technical idea of the invention are possible. is there.

Note that a semiconductor display device may be formed by transferring a semiconductor element manufactured using the above method onto a flexible substrate such as plastic. For transfer, a metal oxide film is provided between the substrate and the semiconductor element, the metal oxide film is weakened by crystallization, and the semiconductor element is peeled off.
A method of transferring, an amorphous silicon film containing hydrogen is provided between the substrate and the semiconductor element, and the substrate and the semiconductor element are separated by removing the amorphous silicon film by laser light irradiation or etching;
Various methods can be used such as a transfer method, a method in which a semiconductor element is formed by mechanically deleting or removing the substrate by etching with a solution or gas, and separating and transferring the semiconductor element from the substrate. Note that the transfer may be performed before the display element is manufactured, or may be transferred after the display element is manufactured.

In this embodiment, a positional relationship between a driver circuit and a protection circuit included in the semiconductor display device of the present invention will be described.

FIG. 8A shows a block diagram of the signal line driver circuit of this embodiment. In FIG. 8A, 9
00 is a pixel portion, 901 is a signal line driver circuit, 902 is a protection circuit, and 903 is an input terminal. The signal line driver circuit 901 includes a shift register 904, a latch A 905, and a latch B 906.
have.

A clock signal (CLK) and a start pulse signal (SP) are input to the shift register 904. In addition to CLK and SP, a switching signal (L / R) may be input. When CLK and SP are input, a timing signal is generated in the shift register 904. Further, the order in which the pulses of the timing signal appear can be switched by L / R. The generated timing signal is sequentially input to the first-stage latch A905. When a timing signal is input to the latch A905, the video signal (VS) is sequentially written and held in the latch A905 in synchronization with the pulse of the timing signal. In this embodiment, video signals are sequentially written in the latch A 905, but the present invention is not limited to this configuration. A plurality of stages of latches A905 may be divided into several groups, and so-called divided driving may be performed in which video signals are input in parallel for each group. Note that the number of groups at this time is called the number of divisions. For example, when the latches are divided into groups for every four stages, it is said that the driving is divided into four.

The time until video signal writing to all the latches of the latch A 905 is completed is called a line period. Actually, the line period may include a period in which a horizontal blanking period is added to the line period.

When the one-line period ends, a latch signal (Latch Signal) is supplied to the second-stage latch B906, and the video signals held in the latch A905 are simultaneously written to the latch B906 in synchronization with the latch signal. Retained. In the latch A 905 that has finished sending the video signal to the latch B 906, the next video signal is sequentially written in synchronization with the timing signal from the shift register 904 again. During the second one line period, the latch B9
The video signal written and held in 06 is input to the pixel portion 900 through the signal line 907.

Instead of the shift register 904, another circuit capable of selecting a signal line such as a decoder circuit may be used.

In FIG. 8A, the protection circuit 902 is provided between the signal line driver circuit 901 and the pixel portion 900. The protection circuit 902 is connected to the signal line 907. The protective circuit 902 can prevent various semiconductor elements connected to the signal line 907 from ESD.

Note that FIG. 8A illustrates an example in which the protection circuit 902 is connected to the signal line 907; however, a protection circuit may be provided in the wiring for inputting the video signal (VS) to the signal line driver circuit 901. good.

FIG. 9 shows the shift register 904, the latch A 905, and the latch B 906 shown in FIG.
A specific circuit diagram of the protection circuit 902 is shown as an example. In FIG. 9, the video signal (V
An example in which the protective circuit 908 is provided also in the wiring for inputting S) will be described. As shown in FIG. 9, a buffer, an inverter, or the like may be provided between the circuits.

FIG. 10 shows a specific circuit diagram of a shift register included in the scan line driver circuit and a protection circuit connected to the scan line as an example. In FIG. 10, the scan line driver circuit includes a shift register 1101 and a buffer 1103. Reference numeral 1102 corresponds to a protection circuit, and 1104 corresponds to a scanning line. The scanning line driver circuit may have a level shifter. In the scan line driver circuit, a selection signal is generated when CLK and SP are input to the shift register 1101. The generated selection signal is buffered and amplified in the buffer 1103 and input to the corresponding scanning line 1104. The scanning lines 1104 are connected to the gates of the transistors of pixels for one line. Since the transistors of pixels for one line must be turned on all at once, a buffer 1103 that can flow a large current is used. The protection circuit 1102 is connected to the scanning line 1104.

Instead of the shift register 1101, for example, another circuit capable of selecting a signal line such as a decoder circuit may be used.

Note that in FIG. 8A, the protection circuit 902 connected to the signal line 907 is provided between the signal line driver circuit 901 and the pixel portion 900; however, the present invention is not limited to this structure. The signal line 907 is formed so as to be in contact with the first interlayer insulating film, and the signal line 907 is connected to the wiring formed so as to be in contact with the second interlayer insulating film, and is routed, whereby the protection circuit 907 is formed. The position of can be changed in any way.

FIG. 8B illustrates an example in which the protective circuit 907 connected to the signal line 907 is provided between the input terminal 903 and the signal line driver circuit 901. By routing the wiring 909, the sealing material 910 for sealing the light emitting element between the substrate and the cover material and the protection circuit 907 can be overlapped, and space can be effectively used.

Note that the signal line driver circuit and the scan line driver circuit included in the semiconductor display device of the present invention are not limited to the above structure. The number and layout of the signal line driver circuits can be arbitrarily set by the designer.

Next, a pixel of a light-emitting device, which corresponds to one embodiment of the semiconductor display device of the present invention, is shown in FIG.
Will be described. FIG. 11A shows an equivalent circuit diagram of a pixel, and a signal line 61
14, power supply lines 6115 and 6117, scanning line 6116, light emitting element 6113, TFT 6110 for controlling the input of video signals to the pixel, TFT 6111 for controlling the current value flowing between both electrodes of the light emitting element 6113, the gate electrode of TFT 6111, A capacitor 6112 that holds a voltage between the source regions is included. Note that although the capacitor 6112 is illustrated in FIG.
If it can be covered by the gate capacitance of the TFT 6111 or other parasitic capacitance, it may not be provided.

FIG. 11B illustrates a pixel circuit in which a TFT 6118 and a scan line 6119 are newly provided in the pixel illustrated in FIG. The light emitting element 61 is forcibly arranged by the arrangement of the TFT 6118.
Since a state in which no current flows through 13 can be created, the lighting period can be started simultaneously with or immediately after the start of the writing period without waiting for signal writing to all the pixels. Therefore, the duty ratio is improved, and moving images can be displayed particularly well.

In FIG. 11C, a TFT 6125 and a wiring 612 are newly added to the pixel shown in FIG.
6 is a pixel circuit. In this structure, the gate electrode of the TFT 6125 is connected to the wiring 6126 that is held at a constant potential, so that the potential of the gate electrode is fixed and the TFT 6125 is operated in the saturation region. Also, a TF that is connected in series with the TFT 6125 and operates in a linear region.
A video signal for transmitting information on lighting or non-lighting of the pixel is input to the gate electrode of T6111 through the TFT 6110. Since the value of the voltage between the source region and the drain region of the TFT 6111 operating in the linear region is small, a slight variation in the voltage between the gate electrode and the source region of the TFT 6111 does not affect the value of the current flowing through the light emitting element 6113. Therefore, the value of current flowing through the light emitting element 6113 is determined by the TFT 6125 operating in the saturation region. The light-emitting device having the above structure can improve luminance unevenness of the light-emitting element 6113 due to variation in characteristics of the TFT 6125 and improve image quality. The channel length L _{1 of the} TFT 6125
, Channel width W ₁ , channel length L _{2 of} TFT 6111, and channel width W ₂ are L ₁ / W ₁ : L ₂ /
It may be set to satisfy W ₂ = 5 to 6000: 1. Further, it is preferable in the manufacturing process that both TFTs have the same conductivity type. Further, as the TFT 6125, not only an enhancement type but also a depletion type TFT may be used.

Note that either an analog video signal or a digital video signal may be used in the light-emitting device of the present invention. However, when a digital video signal is used, it differs depending on whether the video signal uses voltage or current. That is, when the light emitting element emits light, a video signal input to the pixel includes a constant voltage signal and a constant current signal. A video signal having a constant voltage includes a constant voltage applied to the light emitting element and a constant current flowing through the light emitting element. In addition, a video signal having a constant current includes a constant voltage applied to the light emitting element and a constant current flowing in the light emitting element. A constant voltage applied to the light emitting element is constant voltage driving, and a constant current flowing through the light emitting element is constant current driving. In constant current driving, a constant current flows regardless of the resistance change of the light emitting element. The light emitting device of the present invention may use either a voltage video signal or a current video signal for driving, and may use either a constant voltage drive or a constant current drive. This embodiment can be freely combined with the above embodiment modes and embodiments.

  In this embodiment, a modified example of the pixel shown in FIG. 11 will be described.

FIG. 12A illustrates an example in which two TFTs 6111a and 6111b connected in series are used instead of the TFT 6111 in the pixel illustrated in FIG. TFT6111
a and 6111b have the same polarity, and the gate electrodes are connected to each other. Note that the number of TFTs used instead is not limited to two but may be plural.

Note that a plurality of TFTs connected in series can be used instead of the TFT 6111 in the pixel illustrated in FIG. Similarly, the pixel shown in FIG.
Instead of T6125, a plurality of TFTs connected in series can be used.

Next, FIG. 12B illustrates an example in which two TFTs 6111a and 6111b connected in parallel are used instead of the TFT 6111 in the pixel illustrated in FIG. TFT61
11a and 6111b have the same polarity, and the gate electrodes are connected to each other. Note that the number of TFTs used instead is not limited to two but may be plural.

Note that a plurality of TFTs connected in parallel can be used instead of the TFT 6111 in the pixel illustrated in FIG. Similarly, the pixel shown in FIG.
Instead of T6125, a plurality of TFTs connected in parallel can be used.

In the pixel shown in FIGS. 11A and 11B, the TFT 6111 is operated in a saturation region, so that the value of current flowing between both electrodes of the light-emitting element 6113 is reduced even when the light-emitting element 6113 is deteriorated. Therefore, a decrease in luminance of the light emitting element 6113 can be suppressed. In addition, in the pixel illustrated in FIG. 11C, by operating the TFT 6125 in the saturation region, even when the light emitting element 6113 is deteriorated, a reduction in the value of current flowing between both electrodes of the light emitting element 6113 is suppressed. Accordingly, a reduction in luminance of the light emitting element 6113 can be suppressed. In this case, it is desirable that the ratio of the channel length to the channel width of the TFTs 6111 and 6125 is high because the linearity of the drain current in the saturation region can be increased and the reduction in luminance due to deterioration can be further suppressed. However, as the channel length increases, the area of the island-shaped semiconductor film included in the TFT increases, and the area ratio (antenna ratio) of the island-shaped semiconductor film and the gate insulating film tends to increase. As in this embodiment, the TFT 61
By using a plurality of TFTs in which island-shaped semiconductor films are separated from each other instead of each of 11 and 6125, an increase in antenna ratio can be suppressed.

FIG. 13 illustrates an example of a top view of the pixel illustrated in FIG. In FIG.
The TFT 6111a and the TFT 6111b include island-shaped semiconductor films 6130 and 61 separated from each other.
31. The TFT 6111b includes the first electrode 61 included in the light-emitting element 6113.
32 are electrically connected to each other through a wiring 6133 and a wiring 6134. The wiring 61
33 is formed on and in contact with the first interlayer insulating film covering the TFTs 6110, 6118, 6111a and 6111b, and the wiring 6134 and the first electrode 6132 are formed on the first interlayer insulating film. The second interlayer insulating film is formed in contact therewith.

In this example, the appearance of a panel of a light-emitting device corresponding to one embodiment of the present invention is described with reference to FIG.
Will be described. 14 is a top view of a panel in which a transistor and a light-emitting element formed over a substrate are sealed with a sealing material between the cover material and FIG. 14B is a plan view of FIG.
This corresponds to a cross-sectional view taken along line AA ′ in FIG.

A sealant 4005 is provided so as to surround the pixel portion 4002, the signal line driver circuit 4003, the scan line driver circuit 4004, and the protection circuit 4020 provided over the substrate 4001. A cover member 4006 is provided over the pixel portion 4002, the signal line driver circuit 4003, and the scan line driver circuit 4004. Therefore, the pixel portion 4002 and the signal line driver circuit 40 are connected.
03 and the scanning line driving circuit 4004 include a substrate 4001, a sealing material 4005, and a cover material 40.
06 together with the filler 4007.

Further, the pixel portion 4002, the signal line driver circuit 4003, the scan line driver circuit 4004, and the protection circuit 4020 provided over the substrate 4001 include a plurality of TFTs.
The TFT 4008 included in the signal line driver circuit 4003, the TFTs 4009a and 4009b included in the protection circuit 4020, and the TFT 4010 included in the pixel portion 4002 are shown. The TFTs 4009 a and 4009 b included in the protection circuit 4020 are diode-connected and connected in series by a wiring 4021.

  Reference numeral 4011 corresponds to a light emitting element and is electrically connected to the TFT 4010.

The lead wiring 4014 corresponds to a wiring for supplying a signal or a power supply voltage to the pixel portion 4002, the signal line driver circuit 4003, the scan line driver circuit 4004, and the protection circuit 4020. The lead wiring 4014 includes a lead wiring 4015a and a lead wiring 401.
It is connected to a connection terminal 4016 via 5b. The connection terminal 4016 is an FPC 4018.
Are electrically connected to each other through an anisotropic conductive film 4019.

Note that as the substrate 4001, a flexible material typified by plastic can be used in addition to glass, metal (typically stainless steel), ceramics, and the like. As plastic, FRP (Fiberglass-Reinforced Plus)
tics) plate, PVF (polyvinyl fluoride) film, mylar film, polyester film or acrylic resin film can be used. A sheet having a structure in which an aluminum foil is sandwiched between PVF films or mylar films can also be used. The cover material 4006 is formed using a light-transmitting material such as a glass plate, a plastic plate, a polyester film, or an acrylic film.

As the filler 4007, in addition to an inert gas such as nitrogen or argon, an ultraviolet curable resin or a thermosetting resin can be used. PVC (polyvinyl chloride), acrylic, polyimide, epoxy resin, silicon resin, PVB (Polyvinyl butyral) or EV
A (ethylene vinyl acetate) can be used. In this example, nitrogen was used as the filler.

In order to expose the filler 4007 to a hygroscopic substance (preferably barium oxide) or a substance capable of adsorbing oxygen, a recess 4007 is provided on the surface of the cover material 4006 on the substrate 4001 side to adsorb the hygroscopic substance or oxygen. A possible substance may be arranged.

Note that the semiconductor display device of the present invention includes in its category a panel in which a pixel portion having a display element is formed and a module in which an IC is mounted on the panel.

The semiconductor display device of the present invention can be used for various electronic devices. Specifically, as an electronic device using the semiconductor display device of the present invention, a video camera, a digital camera, a goggle type display (head-mounted display), a navigation system, a sound reproduction device (
Car audio, audio components, etc.), notebook personal computers, game machines, portable information terminals (mobile computers, mobile phones, portable game machines, electronic books, etc.)
And an image reproducing apparatus (specifically, an apparatus having a display capable of reproducing a recording medium such as a DVD: Digital Versatile Disc) and displaying the image.
Specific examples of these electronic devices are shown in FIGS.

FIG. 15A illustrates a 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 semiconductor display device of the present invention can be used for the display portion 2003. Since the light-emitting device is a self-luminous type, a backlight is not necessary and a display portion thinner than a liquid crystal display can be obtained. The light emitting element display device includes all information display devices such as a personal computer, a TV broadcast receiver, and an advertisement display.

FIG. 15B illustrates a laptop personal computer, which includes a main body 2201 and a housing 2202.
A display portion 2203, a keyboard 2204, an external connection port 2205, a mouse 2206, and the like. The semiconductor display device of the present invention can be used for the display portion 2203.

FIG. 15C illustrates a personal digital assistant (PDA), which includes a main body 2101, a display portion 2102, operation keys 2103, a modem 2104, and the like. The modem 2104 may be built in the main body 2101. The semiconductor display device of the present invention can be used for the display portion 2202.

As described above, the applicable range of the present invention is so wide that it can be used for electronic devices in various fields. Further, the electronic device of this embodiment may use the semiconductor display device having any structure shown in Embodiments 1 to 5.

Claims (8)

A first TFT and a second TFT;
A first interlayer insulating film formed to cover the first TFT and the second TFT;
A first wiring formed on the first interlayer insulating film and diode-connected to one of a source region or a drain region of the first TFT and a gate electrode, and a source region or a drain region of the first TFT A second wiring connected to the other of
A third wiring formed on the first interlayer insulating film and connected to one of a source region or a drain region of the second TFT;
A second interlayer insulating film formed on the first interlayer insulating film so as to cover the first to third wirings;
A fourth wiring formed on the second interlayer insulating film and connected to the second wiring;
A fifth wiring formed on the second interlayer insulating film and connected to the third wiring;
A display device, comprising: a display element formed on the second interlayer insulating film and connected to the fifth wiring. A first TFT to a third TFT;
A first interlayer insulating film formed to cover the first TFT to the third TFT;
A first wiring formed on the first interlayer insulating film and diode-connected to one of a source region or a drain region of the first TFT and a gate electrode, and a source region or a drain region of the first TFT A second wiring connected to the other of
A third wiring formed on the first interlayer insulating film and diode-connected to one of a source region or a drain region of the second TFT and a gate electrode; and a source region or a drain region of the second TFT A fourth wiring connected to the other of
A fifth wiring formed on the first interlayer insulating film and connected to one of a source region and a drain region of the third TFT;
A second interlayer insulating film formed on the first interlayer insulating film so as to cover the first to fifth wirings;
A sixth wiring formed on the second interlayer insulating film and connected to the second wiring and the third wiring;
A seventh wiring formed on the second interlayer insulating film and connected to the fifth wiring;
A display device, comprising: a display element formed on the second interlayer insulating film and connected to the seventh wiring. A first TFT to a third TFT;
A first interlayer insulating film formed to cover the first TFT to the third TFT;
A first wiring formed on the first interlayer insulating film and diode-connected to one of a source region or a drain region of the first TFT and a gate electrode;
Formed on the first interlayer insulating film, connected to the other of the source region or the drain region of the first TFT, and one of the source region or the drain region of the second TFT; and the second TFT A second wiring diode-connected to the gate electrode of
A third wiring formed on the first interlayer insulating film and connected to the other of the source region or the drain region of the second TFT;
A fourth wiring formed on the first interlayer insulating film and connected to one of a source region or a drain region of the third TFT;
A second interlayer insulating film formed on the first interlayer insulating film so as to cover the first to fourth wirings;
A fifth wiring formed on the second interlayer insulating film and connected to the second wiring;
A sixth wiring formed on the second interlayer insulating film and connected to the fourth wiring;
And a display element formed on the second interlayer insulating film and connected to the sixth wiring. In any one of Claims 1 thru | or 3,
The display device is a light-emitting element or a liquid crystal element. In any one of Claims 1 thru | or 4,
The display device, wherein the second interlayer insulating film is formed using a coating method. In any one of Claims 1 thru | or 4,
The display device, wherein the second interlayer insulating film is formed of a stacked insulating film, and any one of the stacked insulating films is formed using a coating method. In any one of Claims 1 thru | or 6,
The display device, wherein the second interlayer insulating film is an organic resin film, an inorganic insulating film, or an insulating film formed using a siloxane-based material. In any one of Claims 1 thru | or 7,
The semiconductor display device is used in any one of a video camera, a digital camera, a goggle type display, a navigation system, an audio playback device, a notebook personal computer, a game machine, a portable information terminal, and an image playback device including a recording medium. A display device.

Images