JP4906106B2 - Light emitting device - Google Patents

Description

  The present invention relates to a light emitting device using a thin film transistor in a driver circuit and a pixel portion.

A semiconductor display device formed using an inexpensive glass substrate has a higher resolution.
The ratio of the area around the pixel portion used for mounting (frame area) to the substrate increases, and miniaturization tends to be hindered. Therefore, it is considered that there is a limit to a method for mounting an IC formed using a single crystal silicon wafer on a glass substrate, and an integrated circuit including a driver circuit is integrally formed on the same glass substrate as a pixel portion. Technology, so-called system-on-panel construction, is regarded as important.

A thin film transistor using a polycrystalline semiconductor film (polycrystalline TFT) has a mobility that is two orders of magnitude higher than that of a TFT using an amorphous semiconductor film, and a pixel portion of a semiconductor display device and its peripheral drive circuit are formed on the same substrate. It has the advantage that it can be integrally formed on top. However, as compared with the case where an amorphous semiconductor film is used, the process is complicated for crystallization of the semiconductor film, so that there is a problem that the yield is reduced and the cost is increased accordingly.

For example, in the case of a laser annealing method generally used for forming a polycrystalline semiconductor film, it is necessary to secure an energy density necessary for enhancing crystallinity. For this reason, there is a limit to the length of the long axis of the laser beam, which reduces the throughput in the crystallization process and causes variations in crystallinity in the vicinity of the edge of the laser beam. Yes. Further, since the energy of the laser beam itself varies, there is a disadvantage that the crystallinity of the semiconductor film varies and it is difficult to uniformly process the object to be processed.

However, the field effect mobility of a TFT in which a channel formation region is formed of an amorphous semiconductor film can be obtained only about 0.4 to 0.8 cm ² / V · sec at most. Therefore, although it can be used as a switching element in the pixel portion, high-speed operation is required such as a scanning line driving circuit for selecting a pixel and a signal line driving circuit for supplying a video signal to the selected pixel. It is considered that it is not suitable for a drive circuit.

In particular, in the case of an active matrix light-emitting device among semiconductor display devices, at least two transistors, ie, a transistor that functions as a switching element that controls input of a video signal and a transistor that controls supply of current to the light-emitting element. A transistor is provided in the pixel. The transistor for controlling the supply of current to the light emitting element preferably has a higher on-current than the transistor used as the switching element.
Therefore, in the case of a light emitting device, improvement of TFT mobility is an important issue even in the pixel portion.

In view of the above-described problems, an object of the present invention is to propose a light-emitting device capable of realizing a system-on-panel without complicating a TFT process and suppressing cost.

In the present invention, a thin film transistor (TFT) is manufactured using a semi-amorphous semiconductor film in which crystal grains are dispersed in an amorphous semiconductor film, and the TFT is used for a pixel portion or a driver circuit to emit light. Make the device. A TFT using a semi-amorphous semiconductor film has a mobility of ² to 10 cm ² / V · sec, which is 2 to 20 times the mobility of a TFT using an amorphous semiconductor film. A part or the whole of the pixel portion can be integrally formed on the same substrate as the pixel portion.

Unlike a polycrystalline semiconductor film, a semi-amorphous semiconductor film (microcrystalline semiconductor film) can be directly formed on a substrate as a semi-amorphous semiconductor film. Specifically, SiH
₄ is diluted with H ₂ to a flow rate ratio of ₂ to 1000 times, preferably 10 to 100 times, and plasma CVD is performed.
The film can be formed using a method. The semi-amorphous semiconductor film manufactured using the above method also includes a microcrystalline semiconductor film including crystal grains of 0.5 nm to 20 nm in an amorphous semiconductor. Therefore, unlike the case of using a polycrystalline semiconductor film, it is not necessary to provide a crystallization step after the semiconductor film is formed. And since the length of the long axis of a laser beam has a limit like crystallization using a laser beam, the dimension of a board | substrate does not produce a restriction | limiting. Further, the number of steps in manufacturing the TFT can be reduced, and accordingly, the yield of the light-emitting device can be increased and the cost can be suppressed.

In the present invention, a semi-amorphous semiconductor film may be used at least in the channel formation region. In addition, the channel formation region does not necessarily have to be a semi-amorphous semiconductor in the film thickness direction, and it is sufficient that at least a part of the channel formation region includes a semi-amorphous semiconductor.

In this specification, a light-emitting element includes, in its category, an element whose luminance is controlled by current or voltage. Specifically, the light-emitting element is an OLED (Organic Light Emitter).
ng Diode) and MIM type electron source elements (electron emitting elements) used for FED (Field Emission Display).

The light-emitting device includes a panel in which the light-emitting element is sealed, and a module in which an IC including a controller or the like is mounted on the panel. Furthermore, the present invention relates to an element substrate corresponding to one mode before the light emitting element is completed in the process of manufacturing the light emitting device, and the element substrate includes a unit for supplying current to the light emitting element. Prepare for. The element substrate is
Specifically, only the pixel electrode of the light emitting element may be formed, or after the conductive film to be the pixel electrode is formed and before the pixel electrode is formed by patterning. It can be, and all forms apply.

OLED (Organic Light Emitting D) which is one of the light emitting elements
iode) is the luminescence generated by applying an electric field.
a layer containing an electroluminescent material (hereinafter referred to as an electroluminescent layer), an anode layer, and a cathode layer. The electroluminescent layer is provided between the anode and the cathode, and is composed of a single layer or a plurality of layers. Specifically, a hole injection layer, a hole transport layer, a light emitting layer, an electron injection layer, an electron transport layer, and the like are included in the electroluminescent layer. In some cases, the layer constituting the electroluminescent layer contains an inorganic compound. Luminescence in the electroluminescent layer includes light emission (fluorescence) when returning from the singlet excited state to the ground state and light emission (phosphorescence) when returning from the triplet excited state to the ground state.

The present invention can reduce the step of crystallizing a semiconductor film after film formation, and can realize a system-on-panel configuration of a light-emitting device without complicating the TFT process.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention can be implemented in many different modes, and those skilled in the art can easily understand that the modes and details can be variously changed without departing from the spirit and scope of the present invention. Is done. Therefore, the present invention is not construed as being limited to the description of this embodiment mode.

Next, the structure of the TFT used in the light emitting device of the present invention will be described. FIG. 1 shows a cross-sectional view of a TFT used in a driver circuit and a cross-sectional view of a TFT used in a pixel portion. 101 corresponds to a cross-sectional view of a TFT used in a driver circuit, 102 corresponds to a cross-sectional view of a TFT used in a pixel portion, and 103 corresponds to a cross-sectional view of a light-emitting element to which current is supplied by the TFT 102. The TFTs 101 and 102 are of an inverted stagger type (bottom gate type). Semi-amorphous TFTs are more suitable for use in a drive circuit because n-type TFTs are higher in mobility than p-type, but in the present invention, TFTs may be either n-type or p-type. good. Regardless of which polarity TFT is used, it is desirable that all TFTs formed on the same substrate have the same polarity in order to reduce the number of steps.

The TFT 101 of the driving circuit is a semi-amorphous layer that overlaps the gate electrode 110 with the gate electrode 110 formed on the substrate 100, the gate insulating film 111 covering the gate electrode 110, and the gate insulating film 111 interposed therebetween. First semiconductor film 112 formed of a semiconductor film
And have. Further, the TFT 101 includes a pair of second semiconductor films 113 functioning as a source region or a drain region, and a third semiconductor film 114 provided between the first semiconductor film 112 and the second semiconductor film 113. is doing.

In FIG. 1, the gate insulating film 111 is formed of two layers of insulating films, but the present invention is not limited to this structure. The gate insulating film 111 may be formed of a single layer or three or more layers of insulating films.

The second semiconductor film 113 is formed using an amorphous semiconductor film or a semi-amorphous semiconductor film, and an impurity imparting one conductivity type is added to the semiconductor film. The pair of second semiconductor films 113 are opposed to each other with a region where the channel of the first semiconductor film 112 is formed therebetween.

The third semiconductor film 114 is formed of an amorphous semiconductor film or a semi-amorphous semiconductor film, has the same conductivity type as that of the second semiconductor film 113, and yet has the second semiconductor film 113.
It has the characteristic that conductivity becomes lower than that. Since the third semiconductor film 114 functions as an LDD region, an electric field concentrated on the end portion of the second semiconductor film 113 functioning as a drain region can be relaxed and the hot carrier effect can be prevented. The third semiconductor film 114 is not necessarily provided, but the provision of the third semiconductor film 114 can increase the withstand voltage of the TFT and improve the reliability. Note that in the case where the TFT 101 is n-type, an n-type conductivity type can be obtained without adding an impurity imparting n-type in particular when the third semiconductor film 114 is formed. Therefore, TFT10
When 1 is n-type, it is not always necessary to add n-type impurities to the third semiconductor film 114.
However, an impurity imparting p-type conductivity is added to the first semiconductor film in which the channel is formed, and the conductivity type is controlled so as to be as close to the I-type as possible.

  A wiring 115 is formed so as to be in contact with the pair of second semiconductor films 113.

The TFT 102 of the driver circuit is a semi-amorphous layer that overlaps with the gate electrode 120 formed on the substrate 100, the gate insulating film 111 covering the gate electrode 120, and the gate electrode 120 with the gate insulating film 111 interposed therebetween. First semiconductor film 122 formed of a semiconductor film
And have. Further, the TFT 102 includes a pair of second semiconductor films 123 functioning as a source region or a drain region, and a third semiconductor film 124 provided between the first semiconductor film 122 and the second semiconductor film 123. is doing.

The second semiconductor film 123 is formed using an amorphous semiconductor film or a semi-amorphous semiconductor film, and an impurity imparting one conductivity type is added to the semiconductor film. The pair of second semiconductor films 123 face each other with a region where the channel of the first semiconductor film 122 is formed therebetween.

The third semiconductor film 124 is formed of an amorphous semiconductor film or a semi-amorphous semiconductor film, has the same conductivity type as that of the second semiconductor film 123, and yet has the second semiconductor film 123.
It has the characteristic that conductivity becomes lower than that. Since the third semiconductor film 124 functions as an LDD region, an electric field concentrated on the end portion of the second semiconductor film 123 functioning as a drain region can be relaxed and the hot carrier effect can be prevented. The third semiconductor film 124 is not necessarily provided, but the provision of the third semiconductor film 124 can increase the withstand voltage of the TFT and improve the reliability. Note that in the case where the TFT 102 is n-type, an n-type conductivity type can be obtained without adding an impurity imparting n-type in particular when the third semiconductor film 124 is formed. Therefore, TFT10
When 2 is n-type, it is not always necessary to add n-type impurities to the third semiconductor film 124.
However, an impurity imparting p-type conductivity is added to the first semiconductor film in which the channel is formed, and the conductivity type is controlled so as to be as close to the I-type as possible.

  A wiring 125 is formed so as to be in contact with the pair of second semiconductor films 123.

A first passivation film 140 and a second passivation film 141 made of an insulating film are formed so as to cover the TFTs 101 and 102 and the wirings 115 and 125. T
The passivation film covering the FTs 101 and 102 is not limited to two layers, and may be a single layer,
Three or more layers may be used. For example, the first passivation film 140 can be formed using silicon nitride, and the second passivation film 141 can be formed using silicon oxide. By forming the passivation film using silicon nitride or silicon nitride oxide, it is possible to prevent the TFTs 101 and 102 from being deteriorated by the influence of moisture, oxygen, or the like.

One end of the wiring 125 is connected to the pixel electrode 130 of the light emitting element 103. Further, an electroluminescent layer 131 is formed so as to be in contact with the pixel electrode 130, and a counter electrode 132 is formed so as to be in contact with the electroluminescent layer 131. Note that although the light-emitting element 103 has an anode and a cathode, either one is used as a pixel electrode and the other is used as a counter electrode.

In the present invention, since the first semiconductor film including the channel formation region is formed using a semi-amorphous semiconductor, a TFT having a higher mobility than a TFT using an amorphous semiconductor film can be obtained. Therefore, the driver circuit and the pixel portion can be formed over the same substrate.

Next, a structure of a pixel included in the light emitting device of the present invention will be described. FIG. 2A illustrates one mode of a pixel circuit diagram, and FIG. 2B illustrates one mode of a cross-sectional structure of a pixel corresponding to FIG.

2A and 2B, reference numeral 201 corresponds to a switching TFT for controlling the input of a video signal to the pixel, and reference numeral 202 denotes a drive for controlling the supply of current to the light-emitting element 203. This corresponds to a TFT for use. Specifically, the drain current of the driving TFT 202 is controlled in accordance with the potential of the video signal input to the pixel via the switching TFT 201,
The drain current is supplied to the light emitting element 203. Reference numeral 204 denotes a switching TFT 2
This corresponds to a capacitor for holding a gate-source voltage (hereinafter referred to as a gate voltage) of the driving TFT when 01 is off, and is not necessarily provided.

Specifically, the switching TFT 201 has a gate electrode connected to the scanning line G, a source region and a drain region, one connected to the signal line S and the other connected to the gate of the driving TFT 202. One of a source region and a drain region of the driving TFT 202 is connected to the power supply line V and the other is connected to the pixel electrode 205 of the light emitting element 203. One of the two electrodes of the capacitor 204 is connected to the gate electrode of the driving TFT 202 and the other is connected to the power supply line V.

2A and 2B, the switching TFT 201 is connected in series,
In addition, a multi-gate structure has a structure in which a plurality of TFTs to which gate electrodes are connected share a first semiconductor film. With the multi-gate structure, the off-state current of the switching TFT 201 can be reduced. Specifically, FIG. 2 (A), FIG.
In (B), the switching TFT 201 has a configuration in which two TFTs are connected in series, but a multi-gate structure in which three or more TFTs are connected in series and a gate electrode is connected. It may be. The switching TFT does not necessarily have a multi-gate structure, and may be a normal single-gate TFT having a single gate electrode and channel formation region.

Next, a mode different from those in FIGS. 1 and 2 of the TFT included in the light emitting device of the present invention will be described. FIG. 3 shows a cross-sectional view of a TFT used in a driver circuit and a cross-sectional view of a TFT used in a pixel portion. 301 corresponds to a cross-sectional view of a TFT used in a driver circuit, and 302 corresponds to a cross-sectional view of a TFT used in a pixel portion and a light-emitting element 303 to which current is supplied by the TFT 302.

The TFT 301 of the driving circuit and the TFT 302 of the pixel portion are formed of gate electrodes 310 and 320 formed on the substrate 300, a gate insulating film 311 covering the gate electrodes 310 and 320,
First semiconductor films 312 and 322 formed of semi-amorphous semiconductor films, which overlap with the gate electrodes 310 and 320 with the gate insulating film 311 interposed therebetween, are provided. Then, channel protective films 330 and 331 made of an insulating film are formed so as to cover the channel formation regions of the first semiconductor films 312 and 322. The channel protective films 330 and 331 are provided in order to prevent the channel formation regions of the first semiconductor films 312 and 322 from being etched in the manufacturing process of the TFTs 301 and 302. Furthermore, TFT 301, 302
Is a pair of second semiconductor films 313 and 323 which function as a source region or a drain region.
And third semiconductor films 314 and 324 provided between the first semiconductor films 312 and 322 and the second semiconductor films 313 and 323, respectively.

In FIG. 3, the gate insulating film 311 is formed of two insulating films, but the present invention is not limited to this structure. The gate insulating film 311 may be formed of a single layer or three or more layers of insulating films.

The second semiconductor films 313 and 323 are formed using an amorphous semiconductor film or a semi-amorphous semiconductor film, and an impurity imparting one conductivity type is added to the semiconductor film. The pair of second semiconductor films 313 and 323 face each other with a region where the channel of the first semiconductor film 312 is formed therebetween.

The third semiconductor films 314 and 324 are formed of an amorphous semiconductor film or a semi-amorphous semiconductor film, have the same conductivity type as the second semiconductor films 313 and 323, and are second
The semiconductor films 313 and 323 have characteristics that make the conductivity lower. Since the third semiconductor films 314 and 324 function as LDD regions, the second semiconductor films 314 and 324 function as drain regions.
The electric field concentrated on the end portions of the semiconductor films 313 and 323 can be relaxed and the hot carrier effect can be prevented. The third semiconductor films 314 and 324 are not necessarily provided, but the provision of the third semiconductor films 314 and 324 can increase the pressure resistance of the TFT and improve the reliability. TFTs 301 and 30
When 2 is n-type, n-type conductivity can be obtained without adding an impurity imparting n-type when the third semiconductor films 314 and 324 are formed. Therefore, when the TFTs 301 and 302 are n-type, it is not always necessary to add n-type impurities to the third semiconductor films 314 and 324.
However, an impurity imparting p-type conductivity is added to the first semiconductor film in which the channel is formed, and the conductivity type is controlled so as to be as close to the I-type as possible.

In addition, wirings 315 and 325 are formed so as to be in contact with the pair of second semiconductor films 313 and 323.

A first passivation film 340 and a second passivation film 341 made of an insulating film are formed so as to cover the TFTs 301 and 302 and the wirings 315 and 325. T
The passivation film covering the FTs 301 and 302 is not limited to two layers, but may be a single layer,
Three or more layers may be used. For example, the first passivation film 340 can be formed using silicon nitride, and the second passivation film 341 can be formed using silicon oxide. By forming the passivation film using silicon nitride or silicon nitride oxide, it is possible to prevent the TFTs 301 and 302 from being deteriorated by the influence of moisture, oxygen, or the like.

One end of the wiring 325 is connected to the pixel electrode 370 of the light emitting element 303. Further, an electroluminescent layer 371 is formed in contact with the pixel electrode 370, and a counter electrode 332 is formed in contact with the electroluminescent layer 371. Note that although the light-emitting element 303 has an anode and a cathode, either one is used as a pixel electrode and the other is used as a counter electrode.

  Next, the structure of the element substrate used for the light emitting device of the present invention is shown.

FIG. 4 illustrates a mode of an element substrate in which only the signal line driver circuit 6013 is separately formed and connected to the pixel portion 6012 formed over the substrate 6011. Pixel portion 6012 and scanning line driving circuit 6
014 is formed using a semi-amorphous TFT. By forming the signal line driver circuit using a transistor that can obtain higher mobility than a semi-amorphous TFT, the operation of the signal line driver circuit that requires a higher driving frequency than the scanning line driver circuit can be stabilized. Note that the signal line driver circuit 6013 may be a transistor using a single crystal semiconductor, a TFT using a polycrystalline semiconductor, or a transistor using SOI. A pixel portion 6012;
The potential of the power supply, various signals, and the like are supplied to the signal line driver circuit 6013 and the scan line driver circuit 6014 through the FPC 6015, respectively.

Note that both the signal line driver circuit and the scan line driver circuit may be formed over the same substrate as the pixel portion.

In the case where the driver circuit is separately formed, the substrate on which the driver circuit is formed is not necessarily attached to the substrate on which the pixel portion is formed, and may be attached to, for example, an FPC. FIG. 5A illustrates a mode of an element substrate in which only the signal line driver circuit 6023 is separately formed and connected to the pixel portion 6022 and the scan line driver circuit 6024 which are formed over the substrate 6021. The pixel portion 6022 and the scan line driver circuit 6024 are formed using semi-amorphous TFTs. The signal line driver circuit 6023 is connected to the pixel portion 6022 through the FPC 6025. In the pixel portion 6022, the signal line driver circuit 6023, and the scan line driver circuit 6024,
The potential of each power source, various signals, and the like are supplied via the FPC 6025.

Further, only a part of the signal line driver circuit or a part of the scanning line driver circuit is made semi-amorphous T
An FT may be formed over the same substrate as the pixel portion, and the rest may be separately formed and electrically connected to the pixel portion. FIG. 5B illustrates an analog switch 6033 included in the signal line driver circuit.
A structure is shown in which a is formed over the same substrate 6031 as the pixel portion 6032 and the scan line driver circuit 6034, and a shift register 6033b included in the signal line driver circuit is separately formed over and attached to a different substrate. The pixel portion 6032 and the scan line driver circuit 6034 are formed using semi-amorphous TFTs. The shift register 6033b included in the signal line driver circuit includes an FPC.
It is connected to the pixel portion 6032 through 6035. The pixel portion 6032, the signal line driver circuit, and the scan line driver circuit 6034 are supplied with power supply potential, various signals, and the like by an FPC 6035.
Is supplied through.

As shown in FIGS. 4 and 5, in the light-emitting device of the present invention, part or all of the driver circuit can be formed on the same substrate as the pixel portion using a semi-amorphous TFT.

Note that a method for connecting a separately formed substrate is not particularly limited, and a known COG method, wire bonding method, TAB method, or the like can be used. Further, the connection position is not limited to the positions shown in FIGS. 4 and 5 as long as electrical connection is possible.
In addition, a controller, a CPU, a memory, and the like may be separately formed and connected.

Note that the signal line driver circuit used in the present invention is not limited to a mode having only a shift register and an analog switch. In addition to the shift register and the analog switch, other circuits such as a buffer, a level shifter, and a source follower may be included. The shift register and the analog switch are not necessarily provided. For example, another circuit that can select a signal line such as a decoder circuit may be used instead of the shift register, or a latch or the like may be used instead of the analog switch. May be.

FIG. 6A shows a block diagram of the light-emitting device of the present invention. A light-emitting device illustrated in FIG. 6A includes a pixel portion 701 including a plurality of pixels each including a light-emitting element, and a scan line driver circuit 70 that selects each pixel.
2 and a signal line driver circuit 703 that controls input of a video signal to a selected pixel.

In FIG. 6A, the signal line driver circuit 703 includes a shift register 704 and an analog switch 705. A clock signal (CLK) and a start pulse signal (SP) are input to the shift register 704. Clock signal (CLK) and start pulse signal (
When (SP) is input, a timing signal is generated in the shift register 704 and input to the analog switch 705.

A video signal (video signal) is supplied to the analog switch 705. The analog switch 705 samples the video signal in accordance with the input timing signal and supplies it to the subsequent signal line.

Next, the configuration of the scan line driver circuit 702 is described. The scan line driver circuit 702 includes a shift register 706 and a buffer 707. In some cases, a level shifter may be provided. In the scan line driver circuit 702, a selection signal is generated by inputting a clock signal (CLK) and a start pulse signal (SP) to the shift register 706. The generated selection signal is buffered and amplified in the buffer 707 and supplied to the corresponding scanning line. The gate of the transistor of the pixel for one line is connected to the scanning line.
Since the transistors of pixels for one line must be turned on all at once, a buffer 707 that can flow a large current is used.

In a full-color light emitting device, when video signals corresponding to R (red), G (green), and B (blue) are sequentially sampled and supplied to corresponding signal lines, a shift register 704 and an analog switch 705 Are connected to the analog switch 705 and the pixel portion 701.
This corresponds to about 1/3 of the number of terminals for connecting the signal lines. Therefore, analog switch 7
05 is formed on the same substrate as the pixel portion 701 so that the analog switch 705 is connected to the pixel portion 7.
The number of terminals used for connecting a separately formed substrate can be reduced, the probability of occurrence of a connection failure can be suppressed, and the yield can be increased as compared with the case where the substrate is formed on a substrate different from 01.

FIG. 6B is a block diagram of a light-emitting device of the present invention, which is different from FIG. 6A. FIG.
In B), the signal line driver circuit 713 includes a shift register 714, a latch A715, and a latch B716. The scan line driver circuit 712 has the same structure as that in FIG.

A clock signal (CLK) and a start pulse signal (SP) are input to the shift register 714. When the clock signal (CLK) and the start pulse signal (SP) are input, a timing signal is generated in the shift register 714 and sequentially input to the first-stage latch A715. When a timing signal is input to the latch A715, video signals are sequentially written and held in the latch A715 in synchronization with the timing signal. Note that FIG.
), It is assumed that video signals are sequentially written in the latch A 715, but the present invention is not limited to this configuration. A plurality of stages of latches A715 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 715 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 one line period ends, the latch signal (Latch Si) is sent to the second-stage latch B716.
gnal) is supplied, and the video signal held in the latch A 715 is simultaneously written and held in the latch B 716 in synchronization with the latch signal. Latch video signal B716
The next video signal is sequentially written to the latch A 715 that has been transmitted to the second time in synchronization with the timing signal from the shift register 714 again. During this second line period, the video signal written and held in the latch B 716 is input to the signal line.

Note that the structures illustrated in FIGS. 6A and 6B are merely examples of the light-emitting device of the present invention, and the structures of the signal line driver circuit and the scan line driver circuit are not limited thereto.

  Next, a specific manufacturing method of the light-emitting device of the present invention will be described.

The substrate 10 can be made of a plastic material other than glass or quartz. Also,
You may use what formed the insulating film on metal materials, such as stainless steel and aluminum.
A first conductive film 11 for forming a gate electrode and a gate wiring (scanning line) on the substrate 10.
Form. For the first conductive film 11, a metal material such as chromium, molybdenum, titanium, tantalum, tungsten, aluminum, or an alloy material thereof is used. The first conductive film 11 can be formed by a sputtering method or a vacuum evaporation method. (Fig. 7 (A))

The first conductive film 11 is etched to form gate electrodes 12 and 13. Since the first semiconductor film and the wiring layer are formed over the gate electrode, it is desirable to process the end portion of the gate electrode into a tapered shape. In the case where the first conductive film 11 is formed of a material containing aluminum as a main component, it is preferable to insulate the surface by performing anodization after etching. Although not shown, a wiring connected to the gate electrode can be formed at the same time in this step.
(Fig. 7 (B))

The first insulating film 14 and the second insulating film 15 can be made to function as a gate insulating film by being formed in an upper layer of the gate electrodes 12 and 13. In this case, it is preferable to form a silicon oxide film as the first insulating film 14 and a silicon nitride film as the second insulating film 15. These insulating films can be formed by a glow discharge decomposition method or a sputtering method. In particular, in order to form a dense insulating film with low gate leakage current at a low deposition temperature, a rare gas element such as argon is preferably contained in a reaction gas and mixed into the formed insulating film.

Then, the first semiconductor film 16 is formed on the first and second insulating films. The first semiconductor film 16 is formed of a film including a semiconductor having an intermediate structure between amorphous and crystalline structures (including single crystal and polycrystal). This semiconductor is a semiconductor having a third state which is stable in terms of free energy, and is a crystalline one having a short-range order and having a lattice strain.
It can be dispersed in a non-single-crystal semiconductor as 0 nm. Further, hydrogen or halogen is contained at least 1 atomic% or more as a neutralizing agent for dangling bonds. Here, for convenience, such a semiconductor is referred to as a semi-amorphous semiconductor (SAS). Further, by adding a rare gas element such as helium, argon, krypton, or neon to further promote lattice distortion, stability is improved and a favorable SAS can be obtained.
Such a SAS semiconductor description is disclosed, for example, in US Pat. No. 4,409,134. (Fig. 7 (C))

This SAS can be obtained by glow discharge decomposition of a silicide gas. A typical silicide gas is SiH ₄ , and other Si ₂ H ₆ , SiH ₂ Cl ₂ , SiHCl _{3 are also used.}
SiCl ₄ , SiF ₄ or the like can be used. The formation of the SAS can be facilitated by diluting the silicide gas with one or plural kinds of rare gas elements selected from hydrogen, hydrogen and helium, argon, krypton, and neon. Dilution rate is 10 to 100
It is preferable to dilute the silicide gas in a range of 0 times. Of course, the reaction of the coating by glow discharge decomposition is performed under reduced pressure, but the pressure may be in the range of about 0.1 Pa to 133 Pa. The power for forming the glow discharge is 1 MHz to 120 MHz, preferably 13 MHz to 60
What is necessary is just to supply the high frequency electric power of MHz. The substrate heating temperature is preferably 300 ° C. or less, and 100
A substrate heating temperature of ~ 200 degrees is recommended.

Further, a carbide gas such as CH ₄ and C ₂ H ₆ and a germanium gas such as GeH ₄ and GeF ₄ are mixed in the silicide gas, and the energy bandwidth is 1.5 to 2.4 eV, or 0.
. You may adjust to 9-1.1 eV.

In addition, since SAS exhibits weak n-type conductivity when an impurity element for the purpose of valence electron control is not intentionally added, the first semiconductor film provided with a TFT channel formation region is The threshold value can be controlled by adding an impurity element imparting p-type simultaneously with or after the film formation. The impurity element imparting p-type is typically boron, and an impurity gas such as B ₂ H ₆ or BF ₃ may be mixed into the silicide gas at a rate of 1 ppm to 1000 ppm. The concentration of boron is, for example, 1 × 10 ^{14 to} 6 × 10 ¹⁶ a.
Toms / cm ³ is preferable.

Next, as shown in FIG. 8A, a second semiconductor film 17 is formed. The second semiconductor film 17 is formed without intentionally adding an impurity element for the purpose of valence electron control.
Like the semiconductor film 16, it is preferably formed of SAS. The second semiconductor film 17 is
A third semiconductor film 18 having one conductivity type for forming a source and a drain and a first semiconductor film 1
By forming between the two, it has a buffer layer (buffer layer) function. Therefore, weak n
When the third semiconductor film 18 having the same conductivity type and the one conductivity type is formed on the first semiconductor film 16 having the electrical conductivity of the mold, it is not always necessary. For the purpose of threshold control, when an impurity element imparting p-type is added, the second semiconductor film 17 has an effect of changing the impurity concentration stepwise, and in order to improve the junction formation. This is a preferred form. That is, the formed TFT can have a function as a low concentration impurity region (LDD region) formed between the channel formation region and the source or drain region.

The third semiconductor film 18 having one conductivity type may be formed by adding phosphorus as a typical impurity element when an n-channel TFT is formed, and by adding an impurity gas such as PH ₃ to a silicide gas. good. The third semiconductor film 18 having one conductivity type can be formed using a semiconductor such as SAS, an amorphous semiconductor, or a microcrystalline semiconductor.

As described above, the first insulating film 14 to the third semiconductor film 18 having one conductivity type can be continuously formed without being exposed to the atmosphere. In other words, each stacked interface can be formed without being contaminated by atmospheric components or contaminating impurity elements floating in the atmosphere, so that variations in TFT characteristics can be reduced.

Next, a mask 19 is formed using a photoresist, and the first semiconductor film 16, the second semiconductor film 17, and the third semiconductor film 18 having one conductivity type are etched and separated into island shapes.
(Fig. 8 (B))

Thereafter, a second conductive film 20 for forming wirings connected to the source and drain is formed. The second conductive film 20 is formed of aluminum or a conductive material containing aluminum as a main component, and the layer on the side in contact with the semiconductor film is formed of titanium, tantalum, molybdenum, tungsten, copper, or a nitride of these elements. A laminated structure may be used. For example, the first layer is Ta and 2
Layer 1 is W, layer 1 is TaN, layer 2 is Al, layer 1 is TaN, layer 2 is Cu, layer 1 is T
Combinations of i, the second layer being Al, and the third layer being Ti are also conceivable. Further, an AgPdCu alloy may be used for either the first layer or the second layer. W, Al and Si alloy (Al-Si
), Or a three-layer structure in which TiN is sequentially laminated. Tungsten nitride may be used in place of W, or an alloy film of Al and Ti (Al—Ti) instead of an alloy of Al and Si (Al—Si).
) Or Ti instead of TiN. Aluminum contains elements such as titanium, silicon, scandium, neodymium, and copper in order to improve heat resistance.
You may add 5 atomic%. (Fig. 8 (C))

Next, a mask 21 is formed. The mask 21 is a mask formed to form a wiring connected to the source and drain, and at the same time, the second semiconductor film 17 and the third semiconductor film 18 having one conductivity type are removed to form a channel formation region, a source, Drain region and LD
It is used together as an etching mask for forming the D region. Etching of aluminum or a conductive film containing this as a main component may be performed using a chloride gas such as BCl ₃ or Cl ₂ . Wirings 23 to 26 are formed by this etching process. Further, etching for forming a channel formation region is performed using a fluoride gas such as SF ₆ , NF ₃ , CF ₄ , and in this case, etching with the first semiconductor film 16 serving as a base is performed. Since the selection ratio cannot be taken, the processing time is appropriately adjusted. As described above, a channel-etch TFT structure can be formed. (Fig. 9 (A))

Next, a third insulating film 27 for the purpose of protecting the channel formation region is formed using a silicon nitride film. This silicon nitride film can be formed by sputtering or glow discharge decomposition, but it is intended to prevent the entry of contaminants such as organic substances, metal substances, and water vapor floating in the atmosphere, and it must be a dense film. Is required. By using a silicon nitride film for the third insulating film 27, the oxygen concentration in the first semiconductor film 16 is 5 × 10 ¹⁹ atoms / cm ³ or less, preferably 1 × 10 ¹⁹ at.
oms / cm ³ or less. For this purpose, using silicon as a target,
A silicon nitride film that has been subjected to high-frequency sputtering with a sputtering gas in which a rare gas element such as nitrogen and argon is mixed, and densification is promoted by including the rare gas element in the film. Also, in the glow discharge decomposition method, the silicide gas is 100% inert gas such as argon.
A silicon nitride film formed by diluting to 500 to 500 times is preferable because a dense film can be formed even at a low temperature of 100 degrees or less. Further, if necessary, the fourth insulating film 28 may be laminated with a silicon oxide film. The third insulating film 27 and the fourth insulating film 28 correspond to a passivation film.

On the third insulating film 27 and / or the fourth insulating film 28, the planarizing film 2 is preferably formed.
9 is formed. The planarization film is preferably formed using an insulating film including Si—O bonds and Si—CHx bonds formed using an organic resin such as acrylic, polyimide, or polyamide, or a siloxane-based material as a starting material. Since these materials have water content, it is preferable to provide the sixth insulating film 30 as a barrier film that prevents intrusion and release of moisture. As the sixth insulating film 30, a silicon nitride film as described above may be applied. (Fig. 9 (B))

The pixel electrode 31 is formed after contact holes are formed in the sixth insulating film 30, the planarizing film 29, the third insulating film 27, and the fourth insulating film 28. (Figure 9 (C))

The channel-etched TFT formed as described above can obtain a field effect mobility of ² to 10 cm ² / V · sec by forming a channel formation region with SAS. Therefore, the TFT can be used as a pixel switching element and an element for forming a driving circuit on the scanning line (gate line) side.

The pixel switching element and the scanning line side drive circuit are the same TFT, and the element substrate is a gate electrode forming mask, a semiconductor region forming mask, a wiring forming mask, a contact hole forming mask, and a pixel electrode forming mask. A total of five masks can be formed.

In FIG. 9C, since the TFT of the pixel is n-type, it is preferable to use a cathode as the pixel electrode 31, but in the case of p-type, it is preferable to use an anode. Specifically, a known material having a small work function, such as Ca, Al, CaF, MgAg, AlLi, or the like can be used.

Next, as illustrated in FIG. 10A, a partition wall 33 formed using an organic resin film, an inorganic insulating film, or organic polysiloxane is formed over the sixth insulating film 30. The partition wall 33 has an opening, and the pixel electrode 31 is exposed in the opening. Next, as shown in FIG.
An electroluminescent layer 34 is formed so as to be in contact with the pixel electrode 31 in the opening of the partition wall 33. The electroluminescent layer 34 may be composed of a single layer or may be composed of a plurality of layers stacked. In the case of a plurality of layers, the electron injection layer, the electron transport layer, the light emitting layer, the hole transport layer, and the hole injection layer are stacked in this order on the pixel electrode 31 using the cathode.

Then, a counter electrode 35 using an anode is formed so as to cover the electroluminescent layer 34. The counter electrode 35 is made of ITO, IZO, ITSO, indium oxide, 2-20% zinc oxide (Zn
A transparent conductive film mixed with O) can be used. In addition to the transparent conductive film, a titanium nitride film or a titanium film may be used as the counter electrode 35. In FIG. 10B, ITO is used as the counter electrode 35. The counter electrode 35 may be wiped with a CMP method or a polyvinyl alcohol-based porous material and polished so that the surface thereof is planarized. Further, after polishing using the CMP method, the surface of the counter electrode 35 may be irradiated with ultraviolet rays, oxygen plasma treatment, or the like. Bulkhead 3
3, the pixel electrode 31, the electroluminescent layer 34, and the counter electrode 35 are overlapped to form a light emitting element 36.

Actually, when completed up to FIG. 10B, the protective film (laminate film, UV curable resin film, etc.) is highly airtight and less degassed so as not to be exposed to the outside air.
It is preferable to package (enclose) with a cover material.

7 to 10 show the manufacturing method of the TFT having the structure shown in FIG. 1, the TFT having the structure shown in FIG. 3 can be similarly manufactured. However, in the case of the TFT shown in FIG. 3, channel protective films 330 and 331 are formed on the first semiconductor films 312 and 322 made of SAS so as to overlap with the gate electrodes 310 and 320, respectively. 7 to 1
It is different from zero.

1 and 3, the third insulating film (first passivation film) and the fourth insulating film (second
The contact hole is formed in the passivation film), the pixel electrode is formed, and the partition wall is formed. The partition wall may be formed of an insulating film including Si—O bonds and Si—CHx bonds formed using an organic resin such as acrylic, polyimide, or polyamide, or a siloxane-based material as a starting material. Preferably, an opening is formed on the pixel electrode, and the side wall of the opening is preferably formed as an inclined surface having a continuous curvature.

The semi-amorphous TFT that can be used in the present invention may be either n-type or p-type. However, the semi-amorphous TFT has higher mobility in the n-type than in the p-type, and is more suitable for use in the pixel of the light-emitting device. In this embodiment, a cross-sectional structure of a pixel will be described with an example in which a driving TFT is an n-type.

FIG. 11A is a cross-sectional view of a pixel in the case where the driving TFT 7001 is n-type and light emitted from the light-emitting element 7002 passes to the anode 7005 side. In FIG. 11A, the light-emitting element 7
A cathode 7003 of 002 and a driving TFT 7001 are electrically connected, and the cathode 7003
An electroluminescent layer 7004 and an anode 7005 are stacked in this order. A known material can be used for the cathode 7003 as long as it has a small work function and reflects light. For example, Ca, Al, CaF, MgAg, AlLi, etc. are desirable. The electroluminescent layer 7004
May be composed of a single layer, or may be composed of a plurality of layers stacked. In the case of a plurality of layers, an electron injection layer, an electron transport layer,
A light emitting layer, a hole transport layer, and a hole injection layer are laminated in this order. Note that it is not necessary to provide all of these layers. The anode 7005 is formed using a transparent conductive film that transmits light. For example, ITO, IZO
In addition to ITSO, a transparent conductive film in which 2 to 20% zinc oxide (ZnO) is mixed with indium oxide may be used.

A portion where the cathode 7003, the electroluminescent layer 7004, and the anode 7005 overlap corresponds to the light emitting element 7002. In the case of the pixel shown in FIG. 11A, light emitted from the light-emitting element 7002 passes to the anode 7005 side as indicated by a white arrow.

FIG. 11B is a cross-sectional view of a pixel in the case where the driving TFT 7011 is an n-type and light emitted from the light-emitting element 7012 passes to the cathode 7013 side. In FIG. 11B, the driving TF
On the transparent conductive film 7017 electrically connected to T7011, the cathode 70 of the light-emitting element 7012 is formed.
13 is formed, and an electroluminescent layer 7014 and an anode 7015 are sequentially stacked on the cathode 7013. A shielding film 7 for reflecting or shielding light so as to cover the anode 7015.
016 is formed. As in the case of FIG. 11A, a known material can be used for the cathode 7013 as long as it is a conductive film having a low work function. However, the film thickness is set so as to transmit light (preferably, about 5 nm to 30 nm). For example, Al having a film thickness of 20 nm
Can be used as the cathode 7013. The electroluminescent layer 7014 has a structure shown in FIG.
), It may be composed of a single layer or a plurality of layers stacked. The anode 7015 is not required to transmit light, but as in FIG.
It can be formed using a transparent conductive film. The shielding film 7016 can be formed using, for example, a metal that reflects light, but is not limited to a metal film. For example, a resin to which a black pigment is added can be used.

A portion where the cathode 7013, the electroluminescent layer 7014, and the anode 7015 overlap corresponds to the light emitting element 7012. In the case of the pixel shown in FIG. 11B, light emitted from the light-emitting element 7012 passes to the cathode 7013 side as shown by a hollow arrow.

Next, FIG. 11C is a cross-sectional view of a pixel in the case where the driving TFT 7021 is n-type and light emitted from the light-emitting element 7022 is emitted from both the anode 7025 side and the cathode 7023 side. In FIG. 11C, the transparent conductive film 702 that is electrically connected to the driving TFT 7021.
7, a cathode 7023 of a light emitting element 7022 is formed, and an electroluminescent layer 7024 and an anode 7025 are sequentially stacked on the cathode 7023. As in the case of FIG. 11A, a known material can be used for the cathode 7023 as long as it is a conductive film having a low work function. However, the film thickness is set so as to transmit light. For example, Al having a thickness of 20 nm is used as the cathode 702.
3 can be used. In addition, as in FIG. 11A, the electroluminescent layer 7024 may be formed of a single layer or a stack of a plurality of layers. The anode 7025 can be formed using a transparent conductive film that transmits light, as in FIG.

A portion where the cathode 7023, the electroluminescent layer 7024, and the anode 7025 overlap corresponds to the light-emitting element 7022. In the case of the pixel shown in FIG. 11C, light emitted from the light-emitting element 7022 passes through both the anode 7025 side and the cathode 7023 side as indicated by white arrows.

In this embodiment, the example in which the driving TFT and the light emitting element are electrically connected is shown.
The current control TFT may be connected between the driving TFT and the light emitting element.

Note that a protective film may be formed so as to cover the light-emitting elements in all the pixels illustrated in FIGS. As the protective film, 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, for example, DL
It is desirable to use a C 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.

In FIGS. 11B and 11C, in order to obtain light from the cathode side, in addition to the method of reducing the thickness of the cathode, ITO whose work function is reduced by adding Li is used. There is also a method using.

The light emitting device of the present invention is not limited to the configuration shown in FIG. 11, and various modifications based on the technical idea of the present invention are possible.

In this embodiment, a variation of a pixel using a semi-amorphous TFT included in the light-emitting device of the present invention will be described.

FIG. 12A illustrates one mode of a pixel of this example. A pixel illustrated in FIG. 12A includes a light-emitting element 901, a switching TFT 902 used as a switching element for controlling input of a video signal to the pixel, and a driving TFT for controlling a current value flowing through the light-emitting element 901.
903 and a current control TFT 90 for selecting whether or not to supply current to the light emitting element 901
4. Further, as in this embodiment, a capacitor 905 for holding the potential of the video signal may be provided in the pixel.

The switching TFT 902, the driving TFT 903, and the current control TFT 904 may be either n-type or p-type, but all have the same polarity. And driving TF
T903 is operated in the saturation region, and the current control TFT 904 is operated in the linear region.

Further, L of the driving TFT 903 may be longer than W, and L of the current control TFT 904 may be equal to or shorter than W. More preferably, the ratio of L to W of the driving TFT 903 is 5 or more. With the above configuration, due to the difference in characteristics of the driving TFT 903,
Variation in luminance of the light emitting element 901 between pixels can be further suppressed. The channel length of the driving TFT is L1, the channel width is W1, and the channel length of the current control TFT is L.
2. When the channel width is W2, when L1 / W1: L2 / W2 = X: 1, X is 5 or more and 6
000 or less is desirable. For example, when X = 6000, L1 / W1 = 500 μm /
It is desirable that 3 μm and L2 / W2 = 3 μm / 100 μm.

The gate electrode of the switching TFT 902 is connected to the scanning line G. One of the source and drain of the switching TFT 902 is the signal line S, and the other is the current control TF.
It is connected to the gate electrode of T904. The gate electrode of the driving TFT 903 is connected to the second power supply line Vb. In the driving TFT 903 and the current control TFT 904, the current supplied from the first power supply line Va is the driving TFT 903 and the current control TFT 904.
Are connected to the first power supply line Va and the light emitting element 901 so as to be supplied to the light emitting element 901 as the drain current of the current. In this embodiment, the source of the current control TFT 904 is connected to the first power supply line Va, and the drain of the drive TFT 903 is connected to the pixel electrode of the light emitting element 901.

The source of the driving TFT 903 is connected to the first power supply line Va, and the current control TFT 90 is connected.
4 drains may be connected to the pixel electrode of the light emitting element 901.

The light-emitting element 901 includes an anode, a cathode, and an electroluminescent layer provided between the anode and the cathode. In the case where the cathode is connected to the driving TFT 903 as shown in FIG. 12A, the cathode is a pixel electrode and the anode is a counter electrode. A potential difference is provided between the counter electrode of the light emitting element 901 and the first power supply line Va so that a current in the forward bias direction is supplied to the light emitting element 901. The counter electrode of the light emitting element 901 is connected to the auxiliary electrode W.

One of the two electrodes of the capacitor 905 is connected to the first power supply line Va, and the other is connected to the gate electrode of the current control TFT 904. The capacitor 905 is provided to hold a potential difference between the electrodes of the capacitor 905 when the switching TFT 902 is in a non-selected state (off state). Note that FIG. 12A illustrates a structure in which the capacitor 905 is provided; however, the pixel illustrated in FIG. 12A is not limited to this structure, and the capacitor 905 may not be provided.

In FIG. 12A, the driving TFT 903 and the current control TFT 904 are n-type, and the drain of the driving TFT 903 and the cathode of the light emitting element 901 are connected. Conversely, driving TFT 90
3 and the current control TFT 904 are p-type, the source of the driving TFT 903 and the anode of the light emitting element 901 are connected. In this case, the anode of the light emitting element 901 is a pixel electrode, and the cathode is a counter electrode.

Next, FIG. 12B is a circuit diagram of a pixel in which a TFT (erasing TFT) 906 for forcibly turning off the current control TFT 904 is provided in the pixel shown in FIG. Note that in FIG. 12B, elements already described in FIG. 12A are denoted by the same reference numerals. Note that the first scan line is indicated by Ga and the second scan line is indicated by Gb in order to be distinguished from the second scan line. The erasing TFT 906 has a gate electrode connected to the second scanning line Gb, one of the source and the drain connected to the gate electrode of the current control TFT 904 and the other connected to the first power supply line Va. The erasing TFT 906 may be either n-type or p-type, but has the same polarity as other TFTs in the pixel.

Next, FIG. 12C is a circuit diagram of a pixel in which the gate electrode of the driving TFT 903 is connected to the second scanning line Gb in the pixel shown in FIG. In FIG. 12C,
Elements already described in FIG. 12A are denoted by the same reference numerals. FIG.
As shown in (), by switching the potential applied to the gate electrode of the driving TFT 903, the light emission of the light emitting element 901 can be forcibly terminated regardless of the information included in the video signal.

Next, FIG. 12D illustrates a current control TFT 904 in the pixel illustrated in FIG.
1 is a circuit diagram of a pixel provided with a TFT (erase TFT) 906 for forcibly turning off.
Note that in FIG. 12D, elements already described in FIGS. 12A to 12D and 12C are denoted by the same reference numerals. The erasing TFT 906 has a second gate electrode.
One of the source and the drain is connected to the gate electrode of the current control TFT 904, and the other is connected to the power supply line V. The erasing TFT 906 may be either n-type or p-type, but has the same polarity as other TFTs in the pixel.

Next, FIG. 12E illustrates a structure of a pixel in which a current control TFT is not provided. FIG. 12 (E)
911 is a light emitting element, 912 is a switching TFT, 913 is a driving TFT,
Reference numeral 915 corresponds to a capacitor element, and 916 corresponds to an erasing TFT 916. Switching TFT91
2, the gate electrode is connected to the first scanning line Ga, the source and the drain are connected to the signal line S, and the other is connected to the gate electrode of the driving TFT 913. Driving TFT 91
3, the source is connected to the power supply line V, and the drain is connected to the pixel electrode of the light emitting element 911. The counter electrode of the light emitting element 911 is connected to the auxiliary electrode W. The erasing TFT 916 has a gate electrode connected to the second scanning line Gb, one of the source and the drain connected to the gate electrode of the driving TFT 913, and the other connected to the power supply line V.

Note that the structure of the pixel included in the light-emitting device of the present invention is not limited to the structure shown in this embodiment.

In this example, one mode of a semi-amorphous TFT included in the light-emitting device of the present invention will be described.

FIG. 13A shows a top view of the semi-amorphous TFT of this example, and FIG. 13B shows a cross-sectional view taken along line AA ′ of FIG. 13A. A part 1301 is a gate wiring functioning as a gate electrode, and overlaps a first semiconductor film 1303 formed of a semi-amorphous semiconductor with a gate insulating film 1302 interposed therebetween. In addition, the first semiconductor film 1303
Second semiconductor films 1304a and 1304b functioning as LDD regions are formed so as to be in contact with each other, and third semiconductor films 1305a and 1305b having one conductivity type are provided so as to be in contact with the second semiconductor films 1304a and 1304b. Is formed. Reference numerals 1306 and 1307 correspond to wirings in contact with the third semiconductor films 1305a and 1305b, respectively.

In the semi-amorphous TFT shown in FIG. 13, the channel length can be kept constant by keeping the distance between the third semiconductor film 1305a and the third semiconductor film 1305b constant. Further, by laying out the end portion of the third semiconductor film 1305b so as to be surrounded by the third semiconductor film 1305a, concentration of an electric field on the drain region side of the channel formation region can be reduced. Furthermore, since the ratio of the channel width to the channel length can be increased, the on-state current can be increased.

In this embodiment, an example of a shift register using semi-amorphous TFTs having the same polarity will be described. FIG. 14A shows the structure of the shift register of this embodiment. The shift register illustrated in FIG. 14A includes a first clock signal CLK and a second clock signal C.
It operates using LKb and start pulse signal SP. 1401 is a pulse output circuit,
Its specific structure is shown in FIG.

The pulse output circuit 1401 includes TFTs 801 to 806 and a capacitor 807. TF
In T801, the gate is connected to the node 2, the source is connected to the gate of the TFT 805, and the potential Vdd is applied to the drain. The TFT 802 has a gate connected to the gate of the TFT 806, a drain connected to the gate of the TFT 805, and a potential Vss applied to the source. The TFT 803 has a gate connected to the node 3, a source connected to the gate of the TFT 806, and a potential Vdd applied to the drain. The gate of the TFT 804 is node 2
Further, the drain is connected to the gate of the TFT 805, and the potential Vss is applied to the source. The TFT 805 has a gate connected to one electrode of the capacitor 807 and a drain connected to the node 1.
Further, the source is connected to the other electrode of the capacitor 807 and the node 4. TFT8
In 06, the gate is connected to one electrode of the capacitor 807, the drain is connected to the node 4, and the potential Vss is applied to the source.

Next, operation of the pulse output circuit 1401 illustrated in FIG. 14B is described. However,
CLK, CLKb, and SP are assumed to be Vdd when H level, Vss when L level, and Vss = 0 for simplicity of explanation.

When SP becomes H level, the TFT 801 is turned on, so that the gate potential of the TFT 805 rises. Finally, the gate potential of the TFT 805 is Vdd−Vth (
When Vth becomes the threshold value of the TFTs 801 to 806), the TFT 801 is turned off and enters a floating state. On the other hand, since the TFT 804 is turned on when SP becomes H level,
The potentials of the gates of the TFTs 802 and 806 drop and finally become Vss.
, 806 is turned off. At this time, the gate of the TFT 803 is at the L level and is turned off.

Next, SP becomes L level, the TFTs 801 and 804 are turned off, and the gate potential of the TFT 805 is held at Vdd−Vth. Here, if the gate-source voltage of the TFT 805 exceeds the threshold value Vth, the TFT 805 is turned on.

Next, when the CLK applied to the node 1 changes from the L level to the H level, the TFT 8
Since 05 is on, the potential of the node 4, that is, the source of the TFT 805 starts to rise. Since capacitive coupling due to the capacitive element 807 exists between the gate / source of the TFT 805, the potential of the gate of the TFT 805 that is in a floating state rises again as the potential of the node 4 rises. Eventually, the potential of the gate of the TFT 805 becomes higher than Vdd + Vth, and the potential of the node 4 becomes equal to Vdd. Then, the above-described operation is similarly performed in the pulse output circuit 1401 in the second and subsequent stages, and pulses are output in order.

In this example, the appearance of a panel corresponding to one embodiment of the light-emitting device of the present invention will be described with reference to FIG. 15 is a top view of a panel in which a semi-amorphous TFT and a light-emitting element formed over a first substrate are sealed with a sealing material between the second substrate and FIG.
FIG. 15B 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 provided over the first substrate 4001 and the scan line driver circuit 4004. A second substrate 4006 is provided over the pixel portion 4002 and the scan line driver circuit 4004. Therefore, the pixel portion 4002 and the scan line driver circuit 4004 include the first substrate 4001, the sealant 4005, and the second substrate 400.
6 together with the filler 4007. In addition, a signal line driver circuit 4003 formed using a polycrystalline semiconductor film is mounted over a separately prepared substrate in a region different from the region surrounded by the sealant 4005 over the first substrate 4001. In this example,
An example in which a signal line driver circuit having a TFT using a polycrystalline semiconductor film is bonded to the first substrate 4001 is described; however, a signal line driver circuit is formed using a transistor using a single crystal semiconductor, and the signal line driver circuit is bonded. May be. FIG. 15 illustrates a TFT 4009 formed of a polycrystalline semiconductor film that is included in the signal line driver circuit 4003.

The pixel portion 4002 and the scan line driver circuit 4004 provided over the first substrate 4001 include a plurality of TFTs. In FIG. 15B, the TFT 401 included in the pixel portion 4002 is provided.
0 is illustrated. In this embodiment, it is assumed that the TFT 4010 is a driving TFT, but the TFT 4010 may be a current control TFT or an erasing TFT. The TFT 4010 corresponds to a TFT using a semi-amorphous semiconductor.

Reference numeral 4011 corresponds to a light emitting element, and the pixel electrode included in the light emitting element 4011 is a TFT 40.
10 drains are electrically connected to each other through a wiring 4017. In this embodiment, the counter electrode of the light emitting element 4011 and the transparent conductive film 4012 are electrically connected. Note that the structure of the light-emitting element 4011 is not limited to the structure described in this embodiment. Light emitting element 4011
The structure of the light-emitting element 4011 can be changed as appropriate in accordance with the direction in which light is extracted from the TFT, the polarity of the TFT 4010, and the like.

In addition, a variety of signals and potentials are supplied to the signal line driver circuit 4003 and the scan line driver circuit 4004 or the pixel portion 4002 which are separately formed, which are not illustrated in the cross-sectional view in FIG. And 4015 through a connection terminal 4016.

In this embodiment, the connection terminal 4016 is formed of the same conductive film as the pixel electrode included in the light emitting element 4011. Further, the lead wiring 4014 is formed of the same conductive film as the wiring 4017. The lead wiring 4015 is formed of the same conductive film as the gate electrode of the TFT 4010.

The connection terminal 4016 is electrically connected to a terminal included in the FPC 4018 through an anisotropic conductive film 4019.

Note that as the first substrate 4001 and the second substrate 4006, glass, metal (typically stainless steel), ceramics, or plastic can be used. As plastic, FRP (Fiberglass-Reinforced Plastics) plate, P
A VF (polyvinyl fluoride) film, a mylar film, a polyester film, or an 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.

However, the second substrate must be transparent to the substrate positioned in the light extraction direction from the light emitting element 4011. In that case, a light-transmitting material such as a glass plate, a plastic plate, a polyester film, or an acrylic film is used.

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.

Note that FIG. 15 illustrates an example in which the signal line driver circuit 4003 is separately formed and mounted on the first substrate 4001; however, this embodiment is not limited to this structure. The scan line driver circuit may be separately formed and then mounted, or only part of the signal line driver circuit or part of the scan line driver circuit may be separately formed and then mounted.

  This embodiment can be implemented in combination with the structure described in other embodiments.

Since a light-emitting device using a light-emitting element is a self-luminous type, it has excellent visibility in a bright place and a wide viewing angle compared to a liquid crystal display. Therefore, it can be used for display portions of various electronic devices.

As an electronic device using the light emitting 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 component, etc.), a notebook type personal computer, a game device, A portable information terminal (mobile computer, cellular phone, portable game machine, electronic book, or the like), and an image playback device (specifically, DVD: Digital Versa) provided with a recording medium
a device having a display capable of reproducing a recording medium such as a tile disc) and displaying an image thereof. In particular, in the case of a portable electronic device, it is desirable to use a light-emitting device because there are many opportunities to see the screen from an oblique direction and the wide viewing angle is important. In the present invention, since it is not necessary to provide a crystallization step after the formation of the semiconductor film, it is relatively easy to increase the size of the panel. Therefore, the present invention is very suitable for an electronic device using a large panel of 10 to 50 inches. Useful. Specific examples of these electronic devices are shown in FIGS.

FIG. 16A 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 light emitting device of the present invention is provided with the display unit
By using it for 03, the display device of the present invention is completed. 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 for personal computers, TV broadcast reception, advertisement display, and the like.

FIG. 16B 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 pointing mouse 2206, and the like. By using the light emitting device of the present invention for the display portion 2203, the notebook personal computer of the present invention is completed.

FIG. 16C shows a portable image reproducing device (specifically, a DVD reproducing device) provided with a recording medium.
A main body 2401, a housing 2402, a display portion A 2403, a display portion B 2404, a recording medium (DVD or the like) reading portion 2405, operation keys 2406, a speaker portion 2407, and the like.
A display portion A2403 mainly displays image information, and a display portion B2404 mainly displays character information. Note that an image reproducing device provided with a recording medium includes a home game machine and the like.
By using the light emitting device of the present invention for the display portions A 2403 and B 2404, the image reproducing device of the present invention is completed.

In addition, since the light emitting device consumes power in the light emitting portion, it is desirable to display information so that the light emitting portion is minimized. Therefore, when a light emitting device is used for a display unit mainly including character information, such as a portable information terminal, particularly a mobile phone or a sound reproduction device, it is driven so that character information is formed by the light emitting part with the non-light emitting part as the background. It is desirable to do.

As described above, the applicable range of the present invention is so wide that it can be used for electronic devices in various fields. In addition, the electronic device of this embodiment may use the light emitting device having any structure shown in Embodiments 1 to 4.

Sectional drawing of the light-emitting device of this invention. 6A and 6B are a circuit diagram and a cross-sectional view of a pixel in a light-emitting device of the present invention. Sectional drawing of the light-emitting device of this invention. FIG. 3 shows one embodiment of an element substrate in the light-emitting device of the present invention. FIG. 3 shows one embodiment of an element substrate in the light-emitting device of the present invention. 1 is a block diagram illustrating a configuration of a light emitting device of the present invention. 4A and 4B illustrate a manufacturing process of a light-emitting device of the present invention. 4A and 4B illustrate a manufacturing process of a light-emitting device of the present invention. 4A and 4B illustrate a manufacturing process of a light-emitting device of the present invention. 4A and 4B illustrate a manufacturing process of a light-emitting device of the present invention. FIG. 6 is a cross-sectional view of a pixel in a light-emitting device of the present invention. FIG. 6 is a circuit diagram of a pixel in the light emitting device of the present invention. FIG. 6 illustrates one embodiment of a semi-amorphous TFT in a light-emitting device of the present invention. FIG. 6 illustrates one mode of a shift register used in the light-emitting device of the present invention. 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 light-emitting device of the present invention.

Explanation of symbols

100 Substrate 101 TFT
102 TFT
103 light emitting element 110 gate electrode 111 gate insulating film 112 first semiconductor film 113 second semiconductor film 114 third semiconductor film 115 wiring 120 gate electrode 122 first semiconductor film 123 second semiconductor film 124 third semiconductor Film 125 Wiring 130 Pixel electrode 131 Electroluminescent layer 132 Counter electrode 140 Passivation film 141 Passivation film 201 Switching TFT
202 Driving TFT
203 Light Emitting Element 204 Capacitance Element 205 Pixel Electrode 300 Substrate 301 TFT
302 TFT
303 Light-Emitting Element 310 Gate Electrode 311 Gate Insulating Film 312 First Semiconductor Film 313 Second Semiconductor Film 314 Third Semiconductor Film 315 Wiring 325 Wiring 332 Counter Electrode 340 Passivation Film 341 Passivation Film 330 Channel Protection Film 370 Pixel Electrode 371 Electric Field Light emitting layer 701 Pixel portion 702 Scan line driver circuit 703 Signal line driver circuit 704 Shift register 705 Analog switch 706 Shift register 707 Buffer 712 Scan line driver circuit 713 Signal line driver circuit 714 Shift register 715 Latch A
716 Latch B
801 TFT
802 TFT
803 TFT
804 TFT
805 TFT
806 TFT
807 Capacitance element 901 Light emitting element 902 Switching TFT
903 Driving TFT
904 Current control TFT
905 Capacitor element 906 Erase TFT
911 Light-emitting element 912 Switching TFT
913 Driving TFT
916 TFT for erasing

Claims (3)

And a pixel portion in which the first inverted staggered TFT is arranged, a second inverted staggered TFT is arranged a driving circuit section, but a light-emitting equipment which is formed on the same substrate,
The first and second inverted staggered TFTs are formed on a gate insulating film formed on a gate electrode, a first semiconductor film formed on the gate insulating film, and the first semiconductor film. and a second semiconductor film which is a third semiconductor film and a formed on the second semiconductor layer, respectively,
The first semiconductor film has a semi-amorphous semiconductor structure,
The second semiconductor film has a property of lower conductivity than the third semiconductor film,
Each of the second semiconductor layer and said third semiconductor film is a semiconductor film of a pair,
The one end of the pair of semiconductor films is laid out so as to be surrounded by the other of the pair of semiconductor films ,
A first impurity element for threshold control is added to the first semiconductor film,
A second impurity element having a polarity opposite to that of the first impurity element is added to the third semiconductor film;
The first and second impurity elements are not intentionally added to the second semiconductor film,
The light emitting device is characterized in that the conductivity type of the first semiconductor film is controlled so as to approach the I-type by adding the first impurity element . And a pixel portion in which the first inverted staggered TFT is arranged, a second inverted staggered TFT is arranged a driving circuit section, but a light-emitting equipment which is formed on the same substrate,
The first and second inverted staggered TFTs are formed on a gate insulating film formed on a gate electrode, a first semiconductor film formed on the gate insulating film, and the first semiconductor film. and a second semiconductor film which is a third semiconductor film and a formed on the second semiconductor layer, respectively,
The first semiconductor film has a semi-amorphous semiconductor structure,
The second semiconductor film has a property of lower conductivity than the third semiconductor film,
Each of the second semiconductor layer and said third semiconductor film is a semiconductor film of a pair,
The one end of the pair of semiconductor films is laid out so as to be surrounded by the other of the pair of semiconductor films,
Wherein the first semiconductor film is rather have been crystallized using a laser beam,
A first impurity element for threshold control is added to the first semiconductor film,
A second impurity element having a polarity opposite to that of the first impurity element is added to the third semiconductor film;
The first and second impurity elements are not intentionally added to the second semiconductor film,
The light emitting device is characterized in that the conductivity type of the first semiconductor film is controlled so as to approach the I-type by adding the first impurity element . Oite to claim 1 or claim 2,
The light emitting device, wherein the second semiconductor film has an amorphous semiconductor structure.

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