JP2014063174A - Display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an EL display device having good color balance, in which the light emission luminance of an EL material constituting a red color light emission layer is lower than the light emission luminance of an EL material constituting a blue color light emission layer and an EL material constituting a green color light emission layer.SOLUTION: The EL display device has a TFT 151, a pixel electrode connected electrically to the TFT, an EL element 152 in which the pixel electrode is a cathode or an anode, an insulation layer closing the EL element, means for applying a video signal to the EL element, and means for gamma-correcting a video signal, on the same substrate. The EL element has a first pixel having a blue color light emission layer, a second pixel having a green color light emission layer, and a third pixel having a red color light emission layer. The light emission luminance of an EL material constituting the red color light emission layer is lower than the light emission luminance of an EL material constituting the blue color light emission layer and an EL material constituting the green color light emission layer. The signal of red color is amplified by gamma-correction, and the signal of blue color or green color is attenuated.

Description

The present invention relates to an EL (electroluminescence) display device formed by forming a semiconductor element (an element using a semiconductor thin film, typically a thin film transistor) on a substrate, and an electronic device (electronic) having the EL display device as a display unit. Device).

In recent years, a technique for forming a thin film transistor (hereinafter referred to as TFT) on a substrate has greatly advanced, and application development to an active matrix display device has been advanced.
In particular, a TFT using a polysilicon film is a conventional TFT using an amorphous silicon film.
Since the field effect mobility is higher than that, high-speed operation is possible. For this reason, it is possible to control a pixel, which has been conventionally performed by a drive circuit outside the substrate, with a drive circuit formed on the same substrate as the pixel.

Such an active matrix display device has various advantages such as a reduction in manufacturing cost, a reduction in size of the display device, an increase in yield, and a reduction in throughput by forming various circuits and elements on the same substrate. It is attracting attention as.

In recent years, research on active matrix EL display devices having EL elements as self-luminous elements has been actively conducted. The EL display device is an organic EL display (OELD: Organic EL Dis
play) or organic light emitting diode (OLED)
iode).

Unlike a liquid crystal display device, an EL display device is a self-luminous type. The EL element has an E between a pair of electrodes.
Although the L layer is sandwiched, the EL layer usually has a laminated structure. A typical example is a “hole transport layer / light emitting layer / electron transport layer” stacked structure proposed by Tang et al. Of Kodak Eastman Company. This structure has very high luminous efficiency, and most EL display devices that are currently under research and development employ this structure.

In addition, a hole injection layer / a hole transport layer / a light emitting layer / an electron transport layer or a hole injection layer / a hole transport layer / a light emitting layer / an electron transport layer / an electron injection layer are stacked in this order on the pixel electrode. The structure to do may be sufficient. E
A fluorescent pigment or the like may be doped into the L layer.

Then, a predetermined voltage is applied to the EL layer having the above structure from the pair of electrodes, whereby recombination of carriers occurs in the light emitting layer to emit light.

There are four types of color display methods for EL display devices. There are three types of EL that are compatible with R (red), G (green), and B (blue).
Element formation method, blue or blue-green light emitting EL element and phosphor (fluorescent color conversion layer: CCM
), A transparent electrode for the cathode (counter electrode), and RGB compatible EL
There is a method of stacking elements.

The color filter is a color filter that extracts red, green, and blue light. These color filters are formed at positions corresponding to the pixels, whereby the color of the light extracted for each pixel can be changed. The principle is the same as the colorization method of the liquid crystal display device using the color filter. Note that the position corresponding to the pixel refers to a position that matches the pixel electrode.

However, the color filter is a filter that improves the color purity of transmitted light by extracting light of a specific wavelength. Therefore, when there are few light components of the wavelength which should be taken out, the malfunction of the brightness | luminance of the light of the wavelength being extremely small, or bad color purity may arise.

In known organic EL materials, red with high emission luminance is not realized, and the red emission luminance is lower than the blue and green emission luminances as shown in FIG. When an organic EL material having such light emission characteristics is used for an EL display device, the red light emission luminance of the displayed image is deteriorated.

In addition, since red emission luminance is lower than blue or green emission luminance, a method of using orange light having a wavelength slightly shorter than red as red light has been conventionally performed. However, in this case as well, E
The red light emission luminance of the image displayed by the L display device is low, and when the red image is displayed, it is displayed as orange.

In view of the above, an object of the present invention is to provide an EL display device that displays desired red, blue, and green balanced images on EL elements having different emission luminances of red, blue, and green.

The structure of the invention disclosed in this specification includes a TFT, a pixel electrode electrically connected to the TFT,
An EL display device in which an EL element having the pixel electrode as a cathode or an anode and an insulating layer enclosing the EL element is formed, means for applying an analog image signal to the EL element, and gamma correction of the analog image signal And an electronic device.

In the above configuration, it may be configured to have a memory for storing data for the gamma correction.

According to another aspect of the invention, there is provided a TFT, a pixel electrode electrically connected to the TFT, an EL element having the pixel electrode as a cathode or an anode, an insulating layer enclosing the EL element, and the EL An EL display device having means for applying an analog image signal to an element and means for gamma correcting the analog image signal on the same substrate.

In addition to the above configuration, a configuration may be adopted in which a memory for storing data for the gamma correction is stored on the same substrate.

In the EL display device, a color filter is formed at a position corresponding to the pixel electrode for colorization.

In addition, in order to colorize using another method, the EL element has a blue light emitting layer.
These pixels, a second pixel having a green light emitting layer, and a third pixel having a red light emitting layer may be formed. In this case, a color filter may or may not be used.

In the EL display device, the gamma correction may amplify a red signal or attenuate a blue or green signal.
The gamma correction may be performed independently for blue, green, and red signals.

With such a configuration, even when an EL material with a small red light component having a wavelength to be extracted by the color filter is used, for example, RGB (red, blue, green) light emission is performed by performing gamma correction on the video signal. Adjust RGB to desired RGB (red, blue, green)
It is possible to provide an EL display device that displays an image with good balance.

In the present invention, an EL display device having an EL element that emits light with appropriately controlled light emission luminance is provided by providing means for gamma correcting a signal applied to a pixel of the EL display device.

In addition, by using the EL display device of the present invention as a display portion, an inexpensive and highly visible electronic device can be obtained.

It is a circuit block diagram of an EL display device of the present invention. It is a block diagram at the time of creating the gamma correction table of EL display apparatus of this invention. 10A and 10B illustrate a manufacturing process of an active matrix EL display device. 10A and 10B illustrate a manufacturing process of an active matrix EL display device. 10A and 10B illustrate a manufacturing process of an active matrix EL display device. FIG. 14 is a cross-sectional view of an EL display device. FIG. 11 is a top view of an EL display device. FIG. 14 illustrates an example of an electronic device. FIG. 14 illustrates an example of an electronic device. The figure which shows the characteristic of the light-emitting luminance and current density of EL element (R, G, B).

  An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

FIG. 1 is a block diagram showing an EL display device of the present invention. In FIG. 1, reference numeral 100 denotes an active matrix substrate, which includes source driver circuits 110 and 120, a gate driver circuit 130, and a pixel portion 150. The pixel portion 150 includes pixels arranged in a matrix, and each pixel includes a TFT 151, an EL element 152, and the like. Although not shown for simplification, in this embodiment, colorization is realized using color filters corresponding to R (red), G (green), and B (blue).

Reference numeral 160 denotes a video signal processing circuit, which converts an analog signal input from the outside into a digital signal, an A / D conversion circuit 163, a correction circuit 161 that corrects the digital signal, and converts the corrected digital signal into an analog signal. A D / A conversion circuit 164 is provided. The correction circuit 161 has a correction memory 162. In the display device of the present invention, the video signal 2
00 is gamma corrected. For example, the video signal 200 is corrected based on a gamma correction table stored in the correction memory.

The control circuit 170 controls various signals supplied to the active matrix substrate 100 and the video signal processing circuit 160. A synchronization signal 210 is input to the control circuit 170.

Further, the control circuit 170 is based on the synchronization signal 210 and the source driver circuit 11.
This is a circuit that generates and supplies pulses (start pulse, clock pulse, synchronization signal, etc.) necessary to control the operation timing of 0 and 120, the gate driver circuit 130, the video signal processing circuit 160, and the like.

Note that the control circuit 170 uses the oscillation clock signal (OSC) output from the phase-synchronized oscillator as the original oscillation with reference to the input synchronization signal 210 as a reference, and has a preset count number (frequency division ratio). Repeats the operation of counting the clock (frequency division). Simultaneously with this frequency division, the clock is counted and the horizontal start pulse (S_SP) and clock pulse (S_CK) supplied to the source driver circuit, and the vertical start pulse (G_SP) and clock pulse supplied to the gate driver circuit are displayed. (G_CK) and a clock pulse (D_CK) are generated. Furthermore, a horizontal synchronizing signal (HSY) and a vertical synchronizing signal (VSY) may be created.

The video signal processing circuit 160, the control circuit 170, etc. are connected to the active matrix substrate 1
It is mounted on a substrate different from 00, such as another printed circuit board, and the circuit on the substrate and the active matrix substrate 100 are connected by a cable, a flexible wiring board, or the like. Needless to say, it is preferable that part or all of the circuits such as the video signal processing circuit 160 and the control circuit 170 be provided on the same substrate as the active matrix substrate because integration and downsizing can be achieved.

The video signal 200 input from the outside to the video signal processing circuit 160 is an analog signal. The video signal 200 may be an analog signal such as a television signal or a video signal,
A data signal from a computer or the like may be D / A converted into an analog signal.

In the video signal processing circuit 160, the video signal 200 is converted into a digital video signal by the A / D conversion circuit 163 and output to the correction circuit 161. Based on the gamma correction table stored in the correction memory, the correction circuit 161 performs gamma correction considering the light emission luminance of each EL element on the input digital video signal.

The gamma correction is to correct the supplied image signal in order to obtain a good gradation display. The gamma-corrected digital video signal is converted into an analog video signal by the D / A conversion circuit 164 and supplied to the source driver circuits 110 and 120.

The correction circuit 161 performs gamma correction on the video signal supplied to each EL element, and appropriately controls the emission luminance of blue light emission, green light emission, and red light emission in accordance with the voltage and current of the corrected analog video signal. Can do. For example, as shown in FIG.
When an EL element using a color filter of R, G, and B) is used, the video signal (corresponding to R) is gamma-corrected so that the light emission luminance of R is increased and the respective light emission luminances are the same. Good. Alternatively, the video signal applied to the EL element (corresponding to B or G) may be gamma-corrected so that the emission luminance of B or G is reduced and the respective emission luminances become the same. In addition, R
The video signal to be applied to each EL element may be gamma-corrected so that the emission luminance of B is increased and the emission luminance of B or G is decreased so that the emission luminance becomes the same.

Here, an example of a method for creating a gamma correction table of the correction memory in the correction circuit of the video signal processing circuit 160 of the present invention will be described.

Please refer to FIG. FIG. 2 shows a circuit block diagram when a gamma correction table of a correction memory in the correction circuit of the video signal processing circuit 160 of the present invention is created. An imaging apparatus 201 converts an image displayed by light emission of the EL element into an electric signal.

The imaging device 201 can be another imaging device such as a CCD camera or a digital video camera. Alternatively, a luminance meter or illuminometer that simply measures the brightness and luminance of the displayed image may be used. When a luminance meter or an illuminometer is used, an A / D conversion circuit that converts a signal supplied from these devices into a digital signal may be used.

202 is a digital signal processor (DSP), 203 is a reference signal supply source, and 204 is a signal generator (SG).

The correction circuit 161 of the video signal processing circuit 160 performs gamma correction on the digital signal supplied from the signal generator 204, outputs the corrected digital video signal, converts it to an analog video signal by the D / A conversion circuit, Send to EL element. Each EL element emits light based on the analog video signal supplied from the video signal processing circuit 160 and displays an image.

The displayed video is converted into a digital signal using the imaging device 201. A digital signal transmitted from the imaging apparatus 200 is a digital signal processor (DSP).
202. The digital signal processor 202 compares the digital signal supplied from the imaging device 201 with the digital signal supplied from the reference data supply source 203 and feeds back the data shift to the correction circuit 161. The reference data may be directly supplied from the signal generator 204.

According to the signal supplied from the digital signal processor 202, the correction circuit 161
The digital signal from the signal generator 204 is further corrected, converted into an analog video signal, and sent again to the EL element. Each EL element emits light based on the analog video signal supplied from the video signal processing circuit 160 and displays an image.

The displayed video is converted into a digital signal again using the imaging device 201. Imaging device 20
The digital signal supplied from 1 is sent to the digital signal processor 202. The digital signal processor 202 compares the digital signal supplied from the imaging device 201 with the digital signal supplied from the reference data supply source 203 and feeds back the deviation to the correction circuit 161 again.

When appropriate gamma correction data is obtained in this way, the data is stored at a designated address in the correction memory 162.

Thereafter, in order to start correction of the next video signal, the signal generator 204 sends a digital signal different from the previous one to the correction circuit 161. When appropriate gamma correction data for the digital signal is obtained, the data is stored in the designated address of the correction memory 162.

When all the correction data is stored in the correction memory 162, the signal generator 204 and the digital signal processor 202 are disconnected from the active matrix substrate 100. This completes the creation of the gamma correction table. Note that the gamma correction table creation method shown here is merely an example, and it goes without saying that the method is not particularly limited. The block circuit diagram shown in FIG. 1 is also an example. For example, gamma correction can be performed using a correction circuit without a correction memory.

Thereafter, the digital video signal is supplied to the correction circuit 160, the digital video signal is corrected based on the data of the gamma correction table stored in the correction memory 161, and further converted into an analog video signal. Supplied.
Since the analog video signal supplied to the EL element is appropriately corrected by the correction circuit 160, balanced light emission (red light emission, green light emission, and blue light emission) can be obtained, and a good image can be displayed. Is done.

The present invention having the above-described configuration will be described in more detail with the following examples.

  In this embodiment, an EL display device including a correction circuit will be described with reference to FIG.

FIG. 1 is a block diagram showing an EL display device of this embodiment. In FIG. 1, reference numeral 100 denotes an active matrix substrate, which includes source driver circuits 110 and 120, a gate driver circuit 130, and a pixel portion 150. The pixel portion 150 includes pixels arranged in a matrix, and each pixel includes a TFT 151, an EL element 152, and the like. In addition,
Although not shown for simplification, in this embodiment, colorization is realized using color filters corresponding to R (red), G (green), and B (blue).

Reference numeral 160 denotes a video signal processing circuit, an A / D conversion circuit 163 that converts an analog signal input from the outside into a digital signal, and a correction circuit 161 that performs gamma correction on the digital signal.
A D / A conversion circuit 164 that converts the gamma-corrected digital signal into an analog signal is provided. The correction circuit 161 has a correction memory 162.

A control circuit 170 controls various signals supplied to the active matrix substrate 100 and the video signal processing circuit 160. A synchronization signal 210 is input to the control circuit 170.

In addition, the video signal processing circuit 160, the control circuit 170, and the like are mounted on a substrate different from the active matrix substrate 100, for example, a separate printed circuit board. They are connected by a wiring board or the like.

The video signal 200 input from the outside to the video signal processing circuit 160 is an analog signal such as a television signal or a video signal.

In the video signal processing circuit 160, the video signal 200 is converted into a digital video signal by the A / D conversion circuit 163 and output to the correction circuit 161. Based on the gamma correction table stored in the correction memory, the correction circuit 161 performs gamma correction considering the light emission luminance of each EL element on the input digital video signal. Gamma corrected digital video signal is D / A
The source driver circuits 110 and 120 are converted into analog video signals by the conversion circuit 164.
To be supplied.

The digital video signal is supplied to the correction circuit 160, and the digital video signal is gamma-corrected based on the data of the gamma correction table stored in the correction memory 161, further converted into an analog video signal, and then supplied to the EL element. Is done.
An appropriate gamma correction is applied to the analog video signal supplied to the EL element by the correction circuit 160, so that balanced light emission (red light emission, green light emission, and blue light emission) can be obtained, and a good image can be obtained. Is displayed.

Next, a method for manufacturing the EL display device of this example will be described with reference to FIGS. However,
In order to simplify the description, a CMOS circuit, which is a basic circuit, is illustrated for the drive circuit.

First, as shown in FIG. 3A, a base film 301 is formed to a thickness of 300 nm over a glass substrate 300. In this embodiment, a silicon nitride oxide film is stacked as the base film 302. At this time, the nitrogen concentration in contact with the glass substrate 300 is preferably set to 10 to 25 wt%.

Next, an amorphous silicon film (not shown) having a thickness of 50 nm is formed on the base film 301 by a known film formation method. Note that the semiconductor film is not limited to an amorphous silicon film, and any semiconductor film including an amorphous structure (including a microcrystalline semiconductor film) may be used. Further, a compound semiconductor film including an amorphous structure such as an amorphous silicon germanium film may be used. The film thickness may be 20 to 100 nm.

Then, the amorphous silicon film is crystallized by a known technique to form a crystalline silicon film (also referred to as a polycrystalline silicon film or a polysilicon film) 302. Known crystallization methods include a thermal crystallization method using an electric furnace, a laser annealing crystallization method using laser light, and a lamp annealing crystallization method using infrared light. In this embodiment, crystallization is performed using excimer laser light using XeCl gas.

In this embodiment, a pulse oscillation type excimer laser beam processed into a linear shape is used. However, a rectangular shape, a continuous oscillation type argon laser beam, or a continuous oscillation type excimer laser beam may be used. .

In this embodiment, a crystalline silicon film is used as an active layer of a TFT, but an amorphous silicon film can also be used. It is also possible to form the active layer of the switching TFT that needs to reduce the off-current with an amorphous silicon film and form the active layer of the current control TFT with a crystalline silicon film. Since the amorphous silicon film has low carrier mobility, it is difficult for an electric current to flow and an off current is difficult to flow. That is, the advantages of both an amorphous silicon film that hardly allows current to flow and a crystalline silicon film that easily allows current to flow can be utilized.

Next, as shown in FIG. 3B, a protective film 30 made of a silicon oxide film is formed on the crystalline silicon film 302.
3 is formed to a thickness of 130 nm. This thickness is 100 to 200 nm (preferably 130 to
170 nm). Any other film may be used as long as it is an insulating film containing silicon. This protective film 303 is provided in order to prevent the crystalline silicon film from being directly exposed to plasma when an impurity is added and to enable fine concentration control.

Then, resist masks 304a and 304b are formed thereon, and n is interposed through the protective film 303.
An impurity element imparting a type (hereinafter referred to as an n-type impurity element) is added.
Note that as the n-type impurity element, an element typically belonging to Group 15, typically phosphorus or arsenic can be used. In this embodiment, phosphine (PH ₃ )
Using a plasma doping method in which plasma is excited without mass separation, phosphorus is 1 × 10 ¹⁸ at
Add at a concentration of oms / cm ³ . Of course, an ion implantation method for performing mass separation may be used.

In the n-type impurity regions 305 and 306 formed by this process, an n-type impurity element is 2 ×
The dose is adjusted so as to be contained at a concentration of 10 ^{16 to} 5 × 10 ¹⁹ atoms / cm ³ (typically 5 × 10 ^{17 to} 5 × 10 ¹⁸ atoms / cm ³ ).

Next, as shown in FIG. 3C, the protective film 303 is removed, and the added element belonging to Group 15 is activated. As the activation means, a known technique may be used. In this embodiment, activation is performed by irradiation with excimer laser light. Of course, the pulse oscillation type or the continuous oscillation type may be used, and it is not necessary to limit to the excimer laser beam. However, since the purpose is to activate the added impurity element, it is preferable to irradiate with energy that does not melt the crystalline silicon film. Note that laser light may be irradiated with the protective film 303 attached.

Note that activation by heat treatment may be used in combination with the activation of the impurity element by the laser beam. When activation by heat treatment is performed, 450 to 5 is considered in consideration of the heat resistance of the substrate.
A heat treatment at about 50 ° C. may be performed.

By this step, end portions of the n-type impurity regions 305 and 306, that is, the n-type impurity regions 305,
A boundary portion (junction portion) with the region to which the n-type impurity element existing around 306 is not added becomes clear. This means that when the TFT is later completed, the LDD region and the channel formation region can form a very good junction.

Next, as shown in FIG. 3D, unnecessary portions of the crystalline silicon film are removed, and island-shaped semiconductor films (hereinafter referred to as active layers) 307 to 310 are formed.

Next, as illustrated in FIG. 3E, a gate insulating film 311 is formed to cover the active layers 307 to 310. The gate insulating film 311 is 10 to 200 nm, preferably 50 to 150 n.
An insulating film containing silicon having a thickness of m may be used. This may be a single layer structure or a laminated structure. In this embodiment, a silicon nitride oxide film having a thickness of 110 nm is used.

Next, a conductive film having a thickness of 200 to 400 nm is formed and patterned to form gate electrodes 312-
316 is formed. The ends of the gate electrodes 312 to 316 can be tapered. Note that in this embodiment, the gate electrode and a wiring (hereinafter referred to as a gate wiring) electrically connected to the gate electrode are formed using different materials. Specifically, a material having a resistance lower than that of the gate electrode is used for the gate wiring.
This is because a material that can be finely processed is used for the gate electrode, and a material that has a low wiring resistance is used for the gate wiring even though it cannot be finely processed. Of course, the gate electrode and the gate wiring may be formed of the same material.

The gate electrode may be formed of a single-layer conductive film, but it is preferable to form a stacked film of two layers or three layers as necessary. Any known conductive film can be used as the material of the gate electrode. However, a material that can be finely processed as described above, specifically, that can be patterned to a line width of 2 μm or less is preferable.

Typically, a film made of an element selected from tantalum (Ta), titanium (Ti), molybdenum (Mo), tungsten (W), chromium (Cr), and silicon (Si), or a nitride film of the element (Typically a tantalum nitride film, a tungsten nitride film, a titanium nitride film), an alloy film (typically, a Mo—W alloy, a Mo—Ta alloy), or a silicide film of the above elements (typical) Specifically, a tungsten silicide film or a titanium silicide film) can be used. Of course, it may be used as a single layer or may be laminated.

In this embodiment, a stacked film including a tungsten nitride (WN) film having a thickness of 50 nm and a tungsten (W) film having a thickness of 350 nm is used. This may be formed by sputtering. Further, when an inert gas such as Xe or Ne is added as a sputtering gas, peeling of the film due to stress can be prevented.

At this time, the gate electrodes 313 and 316 are formed so as to overlap part of the n-type impurity regions 305 and 306 with the gate insulating film 311 interposed therebetween. This overlapped portion later becomes an LDD region overlapping with the gate electrode.

Next, as shown in FIG. 4A, an n-type impurity element (phosphorus in this embodiment) is added in a self-aligning manner using the gate electrodes 312 to 316 as masks. Impurity regions 31 thus formed
7 to 323 include 1/2 to 1/10 of n-type impurity regions 305 and 306 (typically 1/3 to 1/3).
Adjust to add phosphorus at a concentration of 1/4).
Specifically, 1 × 10 ^{16 to} 5 × 10 ¹⁸ atoms / cm ³ (typically 3 × 10 ^{17 to} 3 × 10 ¹⁸ ato
A concentration of ms / cm ³ ) is preferred.

Next, as shown in FIG. 4B, resist masks 324a to 324 are formed so as to cover the gate electrodes and the like.
24c is formed, and an n-type impurity element (phosphorus in this embodiment) is added to form impurity regions 325 to 331 containing phosphorus at a high concentration. Here again, ion doping using phosphine (PH ₃ ) is performed, and the concentration of phosphorus in this region is 1 × 10 ²⁰ to 1 × 10 ²¹ atoms / cm ³ (typically 2 × 10 ^{20 to} 5 × 10 ^21. atoms / cm ³ ).

In this step, the source region or drain region of the n-channel TFT is formed. In the switching TFT, the n-type impurity regions 320 to 3 formed in the step of FIG.
Leave part of 22.

Next, as shown in FIG. 4C, the resist masks 324a to 324c are removed, and a new resist mask 332 is formed. Then, a p-type impurity element (boron in this embodiment) is added to form impurity regions 333 and 334 containing boron at a high concentration. Here, diborane (B
₂ × 6 ^{20 to} 3 × 10 ²¹ atoms / cm ³ (typically 5 × 10 ₂ ) by ion doping using ₂ H ₆ ).
Boron is added so that the concentration becomes × 10 ²⁰ to 1 × 10 ²¹ atoms / cm ³ .

Note that phosphorus is already added to the impurity regions 333 and 334 at a concentration of 1 × 10 ²⁰ to 1 × 10 ²¹ atoms / cm ³ , but boron added here is added at a concentration of at least three times that of the impurity regions 333 and 334. Is done. Therefore, the n-type impurity region formed in advance is completely inverted to the P-type and functions as a P-type impurity region.

Next, after removing the resist mask 332, n-type or p-type added at each concentration
Activate the type impurity element. As the activation means, furnace annealing, laser annealing, or lamp annealing can be used. In this embodiment, heat treatment is performed in an electric furnace in a nitrogen atmosphere at 550 ° C. for 4 hours.

At this time, it is important to eliminate oxygen in the atmosphere as much as possible. This is because the presence of even a small amount of oxygen oxidizes the exposed surface of the gate electrode, which increases resistance and makes it difficult to make ohmic contact later. Therefore, the oxygen concentration in the treatment atmosphere in the activation step is 1 ppm or less, preferably 0.1 ppm or less.

Next, when the activation process is completed, a gate wiring 335 having a thickness of 300 nm is formed.
As a material of the gate wiring 335, a metal film containing aluminum (Al) or copper (Cu) as a main component (occupying 50 to 100% as a composition) may be used. As the arrangement, like the gate wiring 211 in FIG. 3, the gate electrodes 314 and 315 (corresponding to the gate electrodes 19a and 19b in FIG. 3) of the switching TFT are formed so as to be electrically connected. (Fig. 4 (D))

With such a structure, the wiring resistance of the gate wiring can be extremely reduced, so that an image display region (pixel portion) having a large area can be formed. That is, the pixel structure of this embodiment is extremely effective in realizing an EL display device having a screen size of 10 inches or more (or 30 inches or more) diagonally.

Next, as shown in FIG. 5A, a first interlayer insulating film 336 is formed. First interlayer insulating film 3
As 36, an insulating film containing silicon may be used as a single layer, or a laminated film combined therewith may be used. The film thickness may be 400 nm to 1.5 μm. In this embodiment, 200n
A structure in which an 800 nm thick silicon oxide film is stacked on an m thick silicon nitride oxide film is employed.

Further, a hydrogenation treatment is performed by performing a heat treatment at 300 to 450 ° C. for 1 to 12 hours in an atmosphere containing 3 to 100% hydrogen. This step is a step in which the dangling bonds of the semiconductor film are terminated with hydrogen by thermally excited hydrogen. As another means of hydrogenation, plasma hydrogenation (using hydrogen excited by plasma) may be performed.

Note that the hydrogenation treatment may be performed while the first interlayer insulating film 336 is formed. That is, 200
After forming a silicon nitride oxide film having a thickness of nm, hydrogenation is performed as described above, and then the remaining 8
A silicon oxide film having a thickness of 00 nm may be formed.

Next, a contact hole is formed in the first interlayer insulating film 336, and the source wiring 337˜
340 and drain wirings 341 to 343 are formed. In this embodiment, this electrode is replaced with T
A laminated film having a three-layer structure in which an i film is 100 nm, an aluminum film containing Ti is 300 nm, and a Ti film 150 nm is continuously formed by sputtering. Of course, other conductive films may be used.

Next, a first passivation film 344 is formed with a thickness of 50 to 500 nm (typically 200 to 300 nm). In this embodiment, the first passivation film 344 is 300 nm.
A thick silicon nitride oxide film is used. This may be replaced by a silicon nitride film.

Note that it is effective to perform plasma treatment using a gas containing hydrogen such as H ₂ or NH ₃ prior to formation of the silicon nitride oxide film. The hydrogen excited by this pretreatment becomes the first interlayer insulating film 336.
The film quality of the first passivation film 344 is improved by performing the heat treatment.
At the same time, since hydrogen added to the first interlayer insulating film 336 diffuses to the lower layer side, the active layer can be effectively hydrogenated.

Next, as shown in FIG. 5B, a second interlayer insulating film 345 made of an organic resin is formed. As the organic resin, polyimide, polyamide, acrylic, BCB (benzocyclobutene), or the like can be used. In particular, since the second interlayer insulating film 345 has a strong meaning of flattening, acrylic having excellent flatness is preferable. In this embodiment, the acrylic film is formed with a film thickness that can sufficiently flatten the step formed by the TFT.
The thickness is preferably 1 to 5 μm (more preferably 2 to 4 μm).

Next, the drain wiring 343 is formed on the second interlayer insulating film 345 and the first passivation film 344.
A contact hole reaching to is formed, and a pixel electrode 346 is formed. In this embodiment, an aluminum alloy film (aluminum film containing 1 wt% titanium) having a thickness of 300 nm is formed as the pixel electrode 346. Reference numeral 347 denotes an end portion of an adjacent pixel electrode.

Next, as shown in FIG. 5C, an alkali compound 348 is formed. In this embodiment, a lithium fluoride film is formed by vapor deposition aiming at a thickness of 5 nm. And 100n on it
An m-thick EL layer 349 is formed by spin coating.

Examples of the EL material forming the EL layer 349 include polymer organic materials such as polyparaphenylene vinylene (PPV) and polyfluorene, and low molecular weight organic materials. Specifically, materials described in Japanese Patent Application Laid-Open No. 8-96959 or Japanese Patent Application Laid-Open No. 9-63770 may be used as the polymer organic material that emits white light to be the light emitting layer. For example, 1, 2
-Dichloromethane, PVK (polyvinylcarbazole), Bu-PBD (2- (4'-t
ert-butylphenyl) -5- (4 ″ -biphenyl) -1,3,4-oxadiazole)
, Coumarin 6, DCM1 (4-dicyanomethylene-2-methyl-6-p-dimethylaminostyryl-4H-pyran), TPB (tetraphenylbutadiene), and Nile Red may be used. At this time, the film thickness is 30 to 150 nm (preferably 40 to 100 n).
m). The above example is an example of an organic material that can be used as the EL layer of the present invention, and does not limit the present invention.

Further, as described above, there are roughly four colorization methods. In this embodiment, a method of forming a color filter corresponding to RGB is used for colorization.
A known material or structure can be used for the EL layer 349, but in the present invention, a low molecular organic material capable of emitting white light is used. Note that the color filter corresponding to RGB may be positioned above the pixel electrode on the active matrix substrate. Further, another substrate may be attached to the active matrix substrate so as to enclose the EL element, and a color filter may be provided on the substrate. For simplicity, the color filter is not shown.

In addition, a color display method in which a blue or blue-green light emitting EL layer and a phosphor (fluorescent color conversion layer: CCM) are combined, or a method in which color display is performed by overlapping EL layers corresponding to RGB can be employed.

Note that although the EL layer 349 has a single-layer structure including only the light-emitting layer in this embodiment, an electron injection layer, an electron transport layer, a hole transport layer, a hole injection layer, an electron blocking layer, or a hole is used as necessary. An element layer may be provided.

Next, an anode 350 made of a 200 nm-thick transparent conductive film is formed so as to cover the EL layer 349.
In this embodiment, a film made of a compound of indium oxide and zinc oxide is formed by a vapor deposition method and patterned to form an anode.

Finally, a second passivation film 351 made of a silicon nitride film is formed by plasma CVD.
It is formed to a thickness of 00 nm. The second passivation film 351 protects the EL layer 349 from moisture and the like. In addition, it plays a role of releasing heat generated in the EL layer 349. In order to further enhance the heat dissipation effect, it is effective to form a second passivation film by laminating a silicon nitride film and a carbon film (preferably a diamond-like carbon film).

Thus, an active matrix EL display device having a structure as shown in FIG. 5C is completed. By the way, the active matrix EL display device of this embodiment can provide extremely high reliability and improve the operating characteristics by arranging TFTs having an optimal structure not only in the pixel portion but also in the drive circuit portion.

First, a TFT having a structure that reduces hot carrier injection so as not to reduce the operating speed as much as possible is used as an n-channel TFT of a CMOS circuit that forms a driving circuit. In addition,
The driving circuit here includes a shift register, a buffer, a level shifter, a sampling circuit (sample and hold circuit), and the like.
In the case of performing digital driving, a signal conversion circuit such as a D / A converter may be included.

In this embodiment, as shown in FIG. 6C, the active layer of the n-channel TFT includes a source region 355, a drain region 356, an LDD region 357, and a channel formation region 358.
The LDD region 357 overlaps with the gate electrode 313 with the gate insulating film 311 interposed therebetween.

The reason why the LDD region is formed only on the drain region side is to prevent the operation speed from being lowered. Further, this n-channel TFT does not need to worry about the off-current value so much, and it is better to focus on the operation speed than that. Therefore, it is desirable that the LDD region 357 is completely overlapped with the gate electrode and the resistance component is reduced as much as possible. That is, it is better to eliminate the so-called offset.

In addition, since the p-channel TFT of the CMOS circuit is hardly concerned with deterioration due to hot carrier injection, it is not particularly necessary to provide an LDD region. Needless to say, it is possible to provide an LDD region as in the case of the n-channel TFT and take measures against hot carriers.

Note that the sampling circuit in the driver circuit is a little special compared to other circuits, and a large current flows in both directions in the channel formation region. That is, the roles of the source region and the drain region are interchanged. Furthermore, it is necessary to keep the off-current value as low as possible, and in that sense, it is desirable to dispose a TFT having an intermediate function between the switching TFT and the current control TFT.

In addition, the said structure can be easily implement | achieved by manufacturing TFT according to the manufacturing process shown to FIGS. In addition, in this embodiment, only the configuration of the pixel portion and the drive circuit is shown. However, according to the manufacturing process of this embodiment, in addition to the signal dividing circuit, the D / A converter circuit,
Logic circuits other than driving circuits such as operational amplifier circuits can be formed on the same substrate,
Further, it is considered that a memory unit, a microprocessor, and the like can be formed.

5C, a sealing material (also referred to as a housing material) 18 is provided so as to surround at least the pixel portion, preferably the driver circuit and the pixel portion. (FIG. 6) The sealing material 18 may be a glass plate having a recess that surrounds the element portion, or an ultraviolet curable resin. At this time, the EL element is completely enclosed in the sealed space and is completely shielded from the outside air.

Further, it is desirable that the gap 20 between the sealing material 18 and the substrate 10 is filled with an inert gas (argon, helium, nitrogen, etc.) or a desiccant such as barium oxide is provided. Thereby, it is possible to suppress deterioration of the EL element due to moisture or the like.

When the EL layer encapsulation process is completed, a connector (flexible printed circuit: FPC17) for connecting the terminal drawn from the element or circuit formed on the substrate and the external signal terminal is attached to complete the product. To do. Incidentally, as shown in FIG.
Is electrically connected to the FPC 17 through a gap between the sealing material 18 and the substrate 300 (however, it is closed with an adhesive 19).

Here, the structure of the active matrix EL display device of this embodiment will be described with reference to the top view of FIG. In FIG. 7, 300 is a substrate, 11 is a pixel portion, 12 is a source side driving circuit, 13
Is a gate side drive circuit, and each drive circuit reaches the FPC 17 via wirings 14 to 16 and is connected to an external device.

In the state shown in FIG. 7 as described above, an image can be displayed on the pixel portion by connecting the FPC 17 to a terminal of an external device. In this specification, an article that can display an image by attaching an FPC is defined as an EL display device.

In this embodiment, the output light of the EL element is output to the upper surface side of the active matrix substrate. However, the EL element is made of ITO in order from the bottom (anode).
It is good also as a structure formed with / EL layer / MgAg electrode (cathode). In this case, the output light of the EL element is output to the substrate side on which the TFT is formed (the lower surface side of the active matrix substrate).

In Example 1, an example using a low molecular weight organic material that emits white light as an EL material constituting the EL layer was shown. However, in this example, R (red), G (green), and B (blue) are used. An example in which three types of polymer organic material layers corresponding to the above are stacked is shown. Since only the EL material is different from Example 1 in this example, only this point will be described.

Instead of the low molecular weight organic material shown in Example 1, a polymer organic material (polyparaphenylene vinylene (PPV), polyfluorene, or the like) may be used. For example, cyanopolyphenylene vinylene was used as the red light emitting material, polyphenylene vinylene was used as the green light emitting material, and polyphenylene vinylene and polyalkylphenylene were used as the blue light emitting material.

With such a configuration, light emission with high emission luminance (red light emission, green light emission, and blue light emission) can be obtained.

In Example 1, laser crystallization is used as means for forming the crystalline silicon film 302.
In this embodiment, a case where different crystallization means are used will be described.

In this embodiment, after an amorphous silicon film is formed, crystallization is performed using the technique described in Japanese Patent Laid-Open No. 7-130652. The technique described in this publication is a technique for obtaining a crystalline silicon film having high crystallinity by using an element such as nickel as a catalyst for promoting (promoting) crystallization.

Further, after the crystallization step is completed, a step of removing the catalyst used for crystallization may be performed. In that case, the catalyst may be gettered by the technique described in JP-A-10-270363 or JP-A-8-330602.

Further, a TFT may be formed using the technique described in the application specification of Japanese Patent Application No. 11-076967 by the present applicant.

As described above, the manufacturing process shown in Example 1 is an example, and FIG.
If other structures can be used, there is no problem.
The configuration of the present embodiment can be freely combined with the configuration of the second embodiment.

In the first embodiment, the case of the top gate type TFT has been described. However, since the present invention is not limited to the TFT structure, a bottom gate type TFT (typically an inverted stagger type TFT) is used.
You may carry out using. Further, the reverse stagger type TFT may be formed by any means.

Since the inverted stagger type TFT has a structure in which the number of steps can be easily reduced as compared with the top gate type TFT, it is very advantageous for reducing the manufacturing cost which is the subject of the present invention. The configuration of this embodiment can be freely combined with the configuration of Embodiment 2 or Embodiment 3.

An EL display device formed by carrying out the present invention is a self-luminous type, and therefore has excellent visibility in a bright place and a wide viewing angle as compared with a liquid crystal display device. Therefore, it can be used as a display portion of various electronic devices. For example, for viewing TV broadcasts on a large screen, the EL of the present invention can be used as a display unit of an EL display (display incorporating an EL display device in a housing) with a diagonal of 30 inches or more (typically 40 inches or more). A display device may be used.

The EL display includes all information display displays such as a personal computer display, a TV broadcast receiving display, and an advertisement display. In addition, the EL display device of the present invention can be used as a display portion of various other electronic devices.

Such electronic devices include video cameras, digital cameras, goggle-type displays (head-mounted displays), car navigation systems, car audio systems, notebook personal computers, game machines, and personal digital assistants (mobile computers, mobile phones, and portable types). A game machine or an electronic book), an image reproducing device provided with a recording medium (specifically, a compact disc (CD), a laser disc (LD) or a digital video disc (
DVD) and the like, and a device provided with a display capable of displaying the image. In particular, since a portable information terminal that is often viewed from an oblique direction emphasizes the wide viewing angle, it is desirable to use an EL display device. Specific examples of these electronic devices are shown in FIG.

FIG. 8A illustrates an EL display, which includes a housing 2001, a support base 2002, and a display portion 200.
3 etc. are included. The present invention can be used for the display portion 2003. Since the EL display is a self-luminous type, a backlight is not necessary, and a display portion thinner than a liquid crystal display can be obtained.

FIG. 8B illustrates a video camera, which includes a main body 2101, a display portion 2102, and an audio input portion 210.
3, an operation switch 2104, a battery 2105, an image receiving unit 2106, and the like. The EL display device of the present invention can be used for the display portion 2102.

FIG. 8C shows a part of the head-mounted EL display (on the right side).
1, signal cable 2202, head fixing band 2203, display unit 2204, optical system 2205
EL display device 2206 and the like. The present invention can be used for the EL display device 2206.

FIG. 8D shows an image reproducing device (specifically, a DVD reproducing device) provided with a recording medium, which includes a main body 2301, a recording medium (CD, LD, DVD, etc.) 2302, an operation switch 2303,
A display portion (a) 2304, a display portion (b) 2305, and the like are included. The display unit (a) mainly displays image information, and the display unit (b) mainly displays character information. The EL display device of the present invention can be used for these display units (a) and (b). Note that the image reproducing device provided with the recording medium may include a CD reproducing device, a game machine, and the like.

FIG. 8E illustrates a portable (mobile) computer, which includes a main body 2401 and a camera unit 240.
2, an image receiving unit 2403, an operation switch 2404, a display unit 2405, and the like. EL of the present invention
The display device can be used for the display portion 2405.

FIG. 8F illustrates a personal computer, which includes a main body 2501, a housing 2502, and a display portion 2.
503, a keyboard 2504, and the like. The EL display device of the present invention can be used for the display portion 2503.

If the light emission luminance of the EL material is increased in the future, the light including the output image information can be enlarged and projected by a lens or the like and used for a front type or rear type projector.

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

Here, FIG. 9A shows a mobile phone, which includes a main body 2601, an audio output portion 2602, an audio input portion 2603, a display portion 2604, operation switches 2605, and an antenna 2606. The EL display device of the present invention can be used for the display portion 2604. Note that the display portion 2604 can suppress power consumption of the mobile phone by displaying white characters on a black background.

FIG. 9B shows a car audio, which includes a main body 2701, a display portion 2702, and operation switches 2703 and 2704. The EL display device of the present invention can be used for the display portion 2702. Moreover, although the vehicle-mounted car audio is shown in the present embodiment, it may be used for a stationary car audio. Note that the display portion 2704 can suppress power consumption by displaying white characters on a black background. This is particularly effective in stationary car audio.

As described above, the application range of the present invention is extremely wide and can be used for electronic devices in various fields. In addition, the electronic apparatus of this example is an E that freely combines the configurations of Examples 1 to 4.
It can be obtained by using an L display device.

Claims (6)

A first EL element above the substrate;
A second EL element above the substrate;
A third EL element above the substrate;
An insulating film above the first EL element, above the second EL element and above the third EL element;
A circuit having a function of performing gamma correction on a video signal corresponding to each of the first EL element, the second EL element, and the third EL element;
The emission color of the first EL element, the emission color of the second EL element, and the emission color of the third EL element are different from each other,
The display device, wherein the insulating film contains carbon. In claim 1,
The display device, wherein the circuit includes a memory that stores data used to perform the gamma correction. In claim 1 or claim 2,
The emission color of the first EL element is red,
The emission color of the second EL element is green,
The display device characterized in that the emission color of the third EL element is blue. In any one of Claims 1 thru | or 3,
Each of the first EL element, the second EL element, and the third EL element includes a light emitting layer containing a polymer organic material. In any one of Claims 1 thru | or 4,
The circuit has a function of amplifying the video signal corresponding to the first EL element and a function of attenuating the video signal corresponding to the second EL element or the third EL element. A display device. In any one of Claims 1 thru | or 5,
A first color filter having a region overlapping with the first pixel electrode of the first EL element;
A second color filter having a region overlapping with the second pixel electrode of the second EL element;
And a third color filter having a region overlapping with a third pixel electrode of the third EL element.

Images