JP2001052864A - Making method of opto-electronical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an EL display device with high operating performance and reliability. SOLUTION: A third passivation film 45 is provided beneath an EL element 203 made up of a pixel electrode (positive electrode) 46, an EL layer 47, and a negative electrode 48, and prevents an alkaline metal in the EL element 203 formed by an ink-jet mode from being diffused toward a TFT(thin-film transistor). The third passivation film 45 prevents water and oxygen from infiltrating from the TFT side, and dissipates the heat generated in the EL element 203 to suppress deterioration of the EL element 203.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an E element formed by forming a semiconductor element (an element using a semiconductor thin film) on a substrate.
The present invention relates to an electro-optical device represented by an L (electroluminescence) display device and an electronic device (electronic device) having the electro-optical device as a display (also referred to as a display unit). In particular, it relates to a method for producing them.

[0002]

2. Description of the Related Art In recent years, the technology for forming a TFT on a substrate has been greatly advanced, and its application to an active matrix type display device has been developed. In particular, a TFT using a polysilicon film is a conventional TFT using an amorphous silicon film.
Since the field-effect mobility (also referred to as mobility) is higher than that of the FT, high-speed operation is possible. Therefore, the control of the pixel, which has been conventionally performed by the drive circuit outside the substrate, can be performed by the drive circuit formed on the same substrate as the pixel.

Such an active matrix type display device has various advantages such as reduction in manufacturing cost, downsizing of the display device, increase in yield, and reduction in throughput by forming various circuits and elements on the same substrate. Is gaining attention.

An active matrix type EL display device is
A switching element formed of a TFT is provided for each pixel, and a driving element for controlling current is operated by the switching element to emit light from the EL layer (light emitting layer). For example, there are EL display devices described in U.S. Pat. No. 5,684,365 (JP-A-8-234683) and JP-A-10-189252.

In order to display these EL display devices in color, attempts have been made to arrange EL layers emitting three primary colors of red (R), green (G) and blue (B) for each pixel.
However, the material generally used for the EL layer is almost an organic material, and its patterning is very difficult. This is because the EL material itself is very weak to moisture and is difficult to handle so that it is easily dissolved in a developing solution.

As a technique for solving such a problem, E
A technique for forming an L layer by an inkjet method has been proposed. For example, JP-A-10-012377 discloses an active matrix EL display in which an EL layer is formed by an inkjet method. Also,
A similar technology is called `` Multicolor Pixel Patterning of Lig
ht-Emitting Polymers by Ink-jet Printing; T.Shimada
et.al., p376-379, SID99 DIGEST ".

[0007] However, since the ink jet method is performed under normal pressure, it is disadvantageous in that the EL layer easily takes in contaminants from the outside air. That is, since the film is formed so as to easily contain mobile ions such as an alkali metal, there is a problem that the diffusion of the alkali metal therefrom may cause a fatal impact on the TFT. In this specification, the term “alkali metal” includes both alkali metals and alkaline earth metals.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a method of manufacturing an electro-optical device having high operation performance and high reliability, particularly a method of manufacturing an EL display device. Make it an issue. An object of the present invention is to improve the quality of an electronic device (electronic device) having the electro-optical device as a display (display unit) by improving the image quality of the electro-optical device.

[0009]

In order to achieve the above object, according to the present invention, diffusion of an alkali metal from an EL element formed by an ink jet method is performed by an insulating film (passivation) provided between the EL element and a TFT. Film). Specifically, an insulating film capable of preventing alkali metal from penetrating is provided over the flattening film covering the TFT. That is, the operating temperature of the EL display device (typically 0 to 0)
A material having a sufficiently low diffusion rate of alkali metal at 100 ° C.) may be used.

[0010] More preferably, it does not transmit moisture and alkali metals and has high thermal conductivity (high heat radiation effect).
An insulating film is selected, and this insulating film is provided in contact with the EL element, or more preferably, the EL element is surrounded by such an insulating film. That is, an insulating film having a blocking effect on moisture and alkali metal and also having a heat radiation effect is provided at a position as close as possible to the EL element, and the deterioration of the EL element is suppressed by the insulating film.

In the case where such an insulating film cannot be used as a single layer, an insulating film having a blocking effect against moisture and alkali metal and an insulating film having a heat radiation effect can be laminated. Further, an insulating film having a blocking effect on moisture, an insulating film having a blocking effect on alkali metal, and an insulating film having a heat radiation effect can be stacked.

In any case, when the EL layer is formed by using the ink jet method, the T element for driving the EL element is used.
It is necessary to take measures to completely protect the FT from the alkali metal. In order to suppress the deterioration of the EL layer itself (also referred to as the deterioration of the EL element), it is necessary to simultaneously take measures against both moisture and heat. I have to take it.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a cross-sectional view of a pixel of an EL display device according to the present invention. FIG. 2A is a top view thereof, and FIG. 2B is a circuit configuration thereof. Actually, a plurality of such pixels are arranged in a matrix to form a pixel portion (image display portion).

The cross-sectional view of FIG. 1 shows a cross section taken along the line AA 'in the top view shown in FIG. Here, since the same reference numerals are used in FIG. 1 and FIG. 2, it is better to refer to both drawings as appropriate. Although two pixels are shown in the top view of FIG. 2, both have the same structure.

In FIG. 1, reference numeral 11 denotes a substrate, and 12 denotes an insulating film serving as a base (hereinafter referred to as a base film). As the substrate 11, a glass substrate, a glass ceramic substrate, a quartz substrate, a silicon substrate, a ceramic substrate, a metal substrate, or a plastic substrate (including a plastic film) can be used.

The base film 12 is particularly effective when a substrate containing mobile ions or a substrate having conductivity is used, but the base film 12 may not be provided on a quartz substrate. As the base film 12, an insulating film containing silicon (silicon) may be used. Note that in this specification, the “insulating film containing silicon” specifically includes silicon, oxygen, or nitrogen at a predetermined ratio, such as a silicon oxide film, a silicon nitride film, or a silicon nitride oxide film (indicated by SiOxNy). Refers to an insulating film.

Dispersing the heat generated by the TFT by providing the base film 12 with a heat radiation effect is also effective in preventing the deterioration of the TFT or the EL element. All known materials can be used to provide a heat radiation effect.

Here, two TFTs are formed in a pixel. 201 is a TF functioning as a switching element
T (hereinafter referred to as switching TFT), 202 is E
The TFT functions as a current control element for controlling the amount of current flowing to the L element (hereinafter, referred to as a current control TFT), and both are formed of n-channel TFTs.

The field effect mobility of an n-channel TFT is p
Because it is larger than the field effect mobility of the channel type TFT,
The operating speed is fast and a large current is easy to flow. Further, even when the same amount of current flows, the TFT size can be made smaller in the n-channel TFT. Therefore, it is preferable to use the n-channel type TFT as the current control TFT because the effective area of the display portion is increased.

A p-channel TFT has the advantage that hot carrier injection hardly causes a problem and the off-state current value is low, and examples of using it as a switching TFT and an example of using it as a current control TFT have already been reported. However, in the present invention, the problem of hot carrier injection and the problem of the off-current value are solved even in the n-channel TFT by adopting a structure in which the position of the LDD region is changed, and all the TFTs in all the pixels are replaced by the n-channel TFT. Another feature is that the TFT is used.

However, in the present invention, it is not necessary to limit the switching TFT and the current control TFT to n-channel TFTs, and it is also possible to use p-channel TFTs for both or any one of them.

The switching TFT 201 includes a source region 13, a drain region 14, LDD regions 15a to 15d,
High concentration impurity region 16 and channel forming regions 17a, 1
Active layer including 7b, gate insulating film 18, gate electrode 19
a, 19b, a first interlayer insulating film 20, a source wiring 21, and a drain wiring 22.

Further, as shown in FIG.
A and 19b have a double gate structure electrically connected by a gate wiring 211 formed of another material (a material having a lower resistance than the gate electrodes 19a and 19b). Of course, not only a double gate structure but also a so-called multi-gate structure (a structure including an active layer having two or more channel forming regions connected in series) such as a triple gate structure may be used. The multi-gate structure is extremely effective in reducing the off-current value. In the present invention, a switching element with a low off-current value is realized by using a multi-gate structure for the pixel switching TFT 201.

The active layer is formed of a semiconductor film having a crystal structure. That is, a single crystal semiconductor film, a polycrystalline semiconductor film, or a microcrystalline semiconductor film may be used. Further, the gate insulating film 18 may be formed using an insulating film containing silicon. As the gate electrode, the source wiring, or the drain wiring, any conductive film can be used.

Further, in the switching TFT 201, the LDD regions 15a to 15d
Are provided so as not to overlap with the gate electrodes 19a and 19b. Such a structure is very effective in reducing the off-current value.

It is more preferable to provide an offset region (a region formed of a semiconductor layer having the same composition as the channel forming region and to which no gate voltage is applied) between the channel forming region and the LDD region in order to reduce the off-current value. . In the case of a multi-gate structure including two or more gate electrodes, a high-concentration impurity region provided between channel formation regions is effective in reducing an off-current value.

As described above, a TFT having a multi-gate structure
Is used as the pixel switching TFT 201, a switching element with sufficiently low off-state current can be realized. Therefore, Japanese Patent Application Laid-Open No. 10-1892
Sufficient time (between one selection and the next selection) without providing a capacitor as shown in FIG.
The gate voltage of the current controlling TFT can be maintained.

That is, it is possible to eliminate the capacitor which has conventionally been a factor for reducing the effective light emitting area.
It is possible to increase the effective light emitting area. This means that the image quality of the EL display device can be made bright.

Next, the current controlling TFT 202 includes an active layer including a source region 31, a drain region 32, an LDD region 33 and a channel forming region 34, a gate insulating film 18, a gate electrode 35, a first interlayer insulating film 20, It is formed to have a wiring 36 and a drain wiring 37. The gate electrode 35 has a single gate structure, but may have a multi-gate structure.

As shown in FIG. 2, the switching TFT
Is electrically connected to the gate of the current controlling TFT. Specifically, the gate electrode 35 of the current controlling TFT 202 is electrically connected to the drain region 14 of the switching TFT 201 via the drain wiring (also referred to as connection wiring) 22. The source wiring 36 is connected to the current supply line 212.

The feature of the current controlling TFT 202 is that the channel width is larger than the channel width of the switching TFT 201. That is, as shown in FIG. 8, the channel length of the switching TFT is L1, and the channel width is W1.
When the channel length of the current controlling TFT is L2 and the channel width is W2, the relational expression of W2 / L2 ≧ 5 × W1 / L1 (preferably W2 / L2 ≧ 10 × W1 / L1) is satisfied. . Therefore, the switching TF
More current than T can easily flow.

The channel length L1 of the switching TFT having the multi-gate structure is the sum of the respective channel lengths of the formed two or more channel forming regions. In the case of FIG. 8, the channel lengths L1a and L1a of the two channel
The sum of 1b is the channel length L1 of the switching TFT.

In the present invention, the channel lengths L1, L2 and the channel widths W1, W2 are not limited to specific numerical ranges, but W1 is 0.1 to 5 μm (typically 1 to 5 μm).
３3 μm), W2 is 0.5-30 μm (typically 2-1
0 μm). At this time, L1 is 0.2 to
18 μm (typically 2 to 15 μm), L2 is 0.1 to 5
It is preferably 0 μm (typically 1 to 20 μm).

In the current control TFT, it is desirable to set the channel length L to be longer in order to prevent the current from flowing excessively. Preferably W2 / L2 ≧ 3
(Preferably W2 / L2 ≧ 5). Desirably, 0.5 to 2 μA per pixel (preferably 1-1.
5 μA).

By setting these numerical ranges, VGA
From the EL display device having the number of pixels of the class (640 × 480), the number of pixels of the HDTV class (1920 × 108)
0 or 1280 × 1024) can cover all standards.

The length (width) of the LDD region formed in the switching TFT 201 is 0.5 to 3.5 μm.
Typically, the thickness may be 2.0 to 2.5 μm.

In the EL display device shown in FIG. 1, the LDD region 33 is provided between the drain region 32 and the channel forming region 34 in the current controlling TFT 202.
Further, the LDD region 33 is characterized in that the LDD region 33 has a region overlapping the gate electrode 35 with the gate insulating film 18 interposed therebetween and a region not overlapping.

The current controlling TFT 202 is connected to the EL element 20.
At the same time as supplying a current for causing the light emitting device 3 to emit light, the supplied amount is controlled to enable gray scale display. Therefore, it is necessary to take measures against deterioration by hot carrier injection so that the deterioration does not occur even when a current flows. When displaying black, the current control TFT 202 is turned off. However, in this case, if the off-current value is high, a clear black display cannot be performed, which causes a decrease in contrast and the like. Therefore, it is necessary to suppress the off-current value.

With respect to deterioration due to hot carrier injection, it is known that a structure in which an LDD region overlaps a gate electrode is very effective. However,
If the entire LDD region is overlapped with the gate electrode, the off-current value increases. Therefore, the present applicant has developed a new structure in which an LDD region that does not overlap the gate electrode is provided in series, thereby taking measures against hot carriers and off-current values. And solve at the same time.

At this time, the length of the LDD region overlapping the gate electrode is 0.1 to 3 μm (preferably 0.3 to 1.5 μm).
m). If the length is too long, the parasitic capacitance is increased, and if it is too short, the effect of preventing hot carriers is weakened. The length of the LDD region that does not overlap with the gate electrode is 1.0 to 3.5 μm (preferably 1.5 to 3.5 μm).
2.0 μm). If it is too long, a sufficient current cannot be supplied, and if it is too short, the effect of reducing the off-current value becomes weak.

In the above structure, the gate electrode and the LD
Since a parasitic capacitance is formed in a region where the D region overlaps, it is preferable not to provide the parasitic capacitance between the source region 31 and the channel formation region 34. Since the current control TFT always has the same flowing direction of carriers (here, electrons), it is sufficient to provide an LDD region only on the drain region side.

From the viewpoint of increasing the amount of current that can flow, the thickness of the active layer (particularly, the channel formation region) of the current control TFT 202 is increased (preferably 50).
To 100 nm, more preferably 60 to 80 nm). Conversely, in the case of the switching TFT 201, from the viewpoint of reducing the off-current value, the thickness of the active layer (particularly, the channel formation region) is reduced (preferably 20 to 50 nm, more preferably 25 to 40 n).
m) is also effective.

Next, reference numeral 41 denotes a first passivation film having a thickness of 10 nm to 1 μm (preferably 200 to 50 μm).
0 nm). As a material, an insulating film containing silicon (in particular, a silicon nitride oxide film or a silicon nitride film is preferable) can be used. The passivation film 41 has a role of protecting the formed TFT from an alkali metal or moisture. The EL layer finally provided above the TFT contains an alkali metal such as sodium. That is, the first passivation film 41 also functions as a protective layer that does not allow these alkali metals (mobile ions) to enter the TFT side.

It is also effective to make the first passivation film 41 have a heat radiation effect to prevent the EL layer from being thermally degraded. However, since the EL display device having the structure of FIG. 1 emits light toward the substrate 11, the first passivation film 41 needs to have translucency. In the case where an organic material is used for the EL layer, it is preferable that an insulating film from which oxygen is easily released be not used because the EL layer is deteriorated by bonding with oxygen.

Prevents the penetration of alkali metals, and furthermore has a heat dissipation effect
B (boron), C (charcoal)
Element) or at least one element selected from N (nitrogen)
And Al (aluminum), Si (silicon), P (phosphorus)
Insulating film containing at least one element selected from
I can do it. For example, aluminum nitride (AlxNy)
Representative nitrides of aluminum, silicon carbide (SixC
y), silicon carbide and silicon nitride (SixN
y), boron nitride (BxN)
y), a boron nitride represented by boron nitride (Bx
Py phosphide represented by Py) can be used.
Noh. Also, substitute for aluminum oxide (AlxOy)
The expressed aluminum oxide has excellent translucency and thermal conductivity
The rate is 20Wm^-1K ^-1Is one of the preferred materials
You. These materials not only have the above effects, but also
There is also the effect of preventing. Note that, in the light-transmitting material,
x and y are arbitrary integers.

It should be noted that other elements can be combined with the above compound. For example, by adding nitrogen to aluminum oxide, aluminum nitride oxide represented by AlNxOy can be used. This material not only has a heat dissipation effect, but also has an effect of preventing intrusion of moisture, alkali metal and the like. In the above aluminum nitride oxide, x, y
Is any integer.

Further, the materials described in JP-A-62-90260 can be used. That is, Si, A
an insulating film containing l, N, O, and M (where M is at least one of rare earth elements, preferably Ce (cerium), Yb
(Ytterbium), Sm (samarium), Er (erbium), Y (yttrium), La (lanthanum), G
d (gadolinium), Dy (dysprosium), Nd
(At least one element selected from (neodymium)). These materials have not only a heat dissipation effect, but also an effect of preventing intrusion of moisture, alkali metal and the like.

Further, a carbon film containing at least a diamond thin film or an amorphous carbon film (especially those having characteristics close to diamond is called a diamond-like carbon film) can be used. These have extremely high thermal conductivity and are extremely effective as heat dissipation layers. However, when the film thickness increases, the film becomes brownish and the transmittance decreases, and thus it is preferable to use the film as thin as possible (preferably 5 to 100 nm).

Since the purpose of the first passivation film 41 is to protect the TFT from alkali metals and moisture, the effect of the first passivation film 41 must not be impaired. Therefore, a thin film made of the material having the above-described heat radiation effect can be used alone. However, these thin films and an insulating film (typically, a silicon nitride film (SixNy) or a nitrided Silicon film (SiOxN
It is effective to stack y)). Note that in the above silicon nitride film or silicon nitride oxide film, x and y are arbitrary integers.

The EL display device is roughly classified into four color display methods, a method of forming three kinds of EL elements corresponding to RGB, a method of combining a white light emitting EL element and a color filter, and a method of forming a blue color. Or E of blue-green emission
There are a system in which an L element and a phosphor (fluorescent color conversion layer: CCM) are combined, and a system in which a transparent electrode is used as a cathode (a counter electrode) and EL devices corresponding to RGB are stacked.

FIG. 1 shows three types of E corresponding to RGB.
This is an example in which a method of forming an L element is used. In addition,
Although only one pixel is shown in FIG. 1, pixels having the same structure are formed corresponding to the respective colors of red, green, and blue, whereby color display can be performed. Known materials may be used for the EL layers of these colors.

However, the present invention can be carried out irrespective of the light emitting method, and all the above four methods can be used in the present invention.

After the first passivation film 41 is formed, a second interlayer insulating film (which may be referred to as a flattening film) 44 is formed so as to cover each TFT, and the step formed by the TFT is flattened. Do. As the second interlayer insulating film 44, a resin film is preferable, and polyimide, polyamide, acrylic, BCB (benzocyclobutene), or the like is preferably used. Of course, if sufficient planarization is possible, an inorganic film may be used.

It is very important that the step caused by the TFT is flattened by the second interlayer insulating film 44. Since an EL layer formed later is extremely thin, poor light emission may be caused by the presence of a step. Therefore, it is desirable that the EL layer be flattened before forming the pixel electrode so that the EL layer can be formed as flat as possible.

Reference numeral 45 denotes a second passivation film, which plays an important role in blocking an alkali metal diffused from the EL element. The thickness may be 5 nm to 1 μm (typically 20 to 300 nm). As the second passivation film 45, an insulating film that can prevent permeation of alkali metal is used. As the material, the material used for the first passivation film 41 can be used.

The second passivation film 45 also functions as a heat dissipation layer that functions to release heat generated in the EL element and prevent heat from being accumulated in the EL element. When the second interlayer insulating film 44 is a resin film, it is weak to heat.
The heat generated in the EL element is prevented from affecting the second interlayer insulating film 44.

As described above, it is effective to flatten the TFT with a resin film in manufacturing an EL display device. However, there has not been a structure which takes into consideration the deterioration of the resin film due to heat generated in the EL element. One of the features of the present invention is that the point is solved by providing the second passivation film 45.

Further, the second passivation film 45 functions as a protective layer for preventing the alkali metal in the EL layer from diffusing to the TFT side while preventing the deterioration due to the above-mentioned heat. It also functions as a protective layer for preventing moisture and oxygen from entering from the TFT side.

One of the important features of the present invention is that the TFT side and the EL element side are separated from each other by an insulating film which has a high heat radiation effect and can prevent the permeation of moisture or alkali metal. It can be said that this is a configuration not found in a conventional EL display device.

Reference numeral 46 denotes a pixel electrode (anode of an EL element) made of a transparent conductive film, and the second passivation film 4
5, second interlayer insulating film 44 and first passivation film 4
After a contact hole (opening) is formed in the TFT 1, the opening is formed so as to be connected to the drain wiring 37 of the current controlling TFT 202.

After the pixel electrode 46 is formed, a bank made of a resin film is formed on the second passivation film 45.
k) Form 101a and 101b. In this embodiment, a photosensitive polyimide film is formed by a spin coating method, and the banks 101a and 101b are formed by patterning. The banks 101a and 101b are used when an EL layer is formed by an ink jet method, and the arrangement of the banks defines a place where an EL element is formed.

After the banks 101a and 101b are formed, an EL layer (preferably an organic material) 47 is formed next. The EL layer 47 is used in a single layer or a laminated structure.
It is often used in a laminated structure. Various laminated structures have been proposed by combining a light emitting layer, an electron transporting layer, an electron injecting layer, a hole injecting layer, a hole transporting layer, and the like, but any structure may be used in the present invention. The EL layer may be doped with a fluorescent dye or the like.

In the present invention, any known EL materials can be used. As a known material, an organic material is widely known, and it is preferable to use an organic material in consideration of a driving voltage. As the organic EL material, for example, the materials disclosed in the following U.S. patents or publications can be used.

US Pat. No. 4,356,429, US Pat. No. 4,539,507, US Pat. No. 4,72
0,432, U.S. Pat. No. 4,769,292,
U.S. Pat. No. 4,885,211; U.S. Pat.
No. 50,950; U.S. Pat. No. 5,059,861;
U.S. Pat. No. 5,047,687, U.S. Pat.
No. 073,446, U.S. Pat. No. 5,059,862
No. 5,061,617; US Pat. No. 5,151,629; US Pat. No. 5,294,86.
9, U.S. Pat. No. 5,294,870;
-189252, JP-A-8-241048, JP-A-8-78159.

Specifically, an organic material represented by the following general formula can be used as the organic material for the hole injection layer.

[0066]

Embedded image

Where Q is N or C—R (carbon chain), M is a metal, metal oxide or metal halide, R is hydrogen, alkyl, aralkyl, allyl or alkaryl, T1, T2 Is an unsaturated 6-membered ring containing substituents such as hydrogen, alkyl or halogen.

The organic material used as the hole transport layer can be an aromatic tertiary amine, and preferably contains tetraallyldiamine represented by the following general formula.

[0069]

Embedded image

Here, Are is an arylene group, and n is 1
To 4, and Ar, R ₇ , R ₈ , and R ₉ are all selected allyl groups.

The organic material used as the EL layer, the electron transport layer or the electron injection layer can be a metal oxinoid compound. As the metal oxinoid compound, a compound represented by the following general formula may be used.

[0072]

Embedded image

Here, R ₂ -R ₇ can be substituted, and the following metal oxinoid compounds can also be used.

[0074]

Embedded image

Here, R ₂ -R ₇ are as defined above, L ₁ -L ₅ is a group of carbohydrates containing 1 to 12 carbon elements, and L ₁ , L ₂ or L ₂ , L ₃ is Together they can form a benzo ring. Further, the following metal oxinoid compounds may be used.

[0076]

Embedded image

Here, R ₂ -R ₆ can be replaced. Thus, the organic EL material includes a coordination compound having an organic ligand. However, the above example is an example of an organic EL material that can be used as the EL material of the present invention,
There is no need to be limited to this.

In the present invention, since an ink-jet method is used as a method for forming an EL layer, a polymer-based material is preferable as a preferable EL material. Typical polymer-based materials include polyparaphenylene vinylene (PPV),
Polyfluorene, polyvinyl carbazole (PVK)
Polymer materials such as a system. To colorize,
For example, cyanopolyphenylene vinylene is preferable for a red light emitting material, polyphenylene vinylene is preferable for a green light emitting material, and polyphenylene vinylene and polyalkylphenylene are preferable for a blue light emitting material.

There are various types of PPV-based organic EL materials, and for example, the following molecular formulas have been published. ("H. Shenk, H. Becker, O. Gelsen, E. Klug
e, W. Kreuder, and H. Spreitzer, “Polymers for Light E
mitting Diodes ”, Euro Display, Proceedings, 1999, p.3
3-37 ")

[0080]

Embedded image

[0081]

Embedded image

Further, polyphenylvinyl having a molecular formula described in JP-A-10-92576 can also be used. The molecular formula is as follows.

[0083]

Embedded image

[0084]

Embedded image

Further, the following molecular formula is used as the PVK-based organic EL material.

[0086]

Embedded image

The polymer organic EL material can be applied by dissolving it in a solvent in a polymer state or by dissolving it in a solvent in a solvent state and applying it. When applied in the form of a monomer, a polymer precursor is first formed and polymerized by heating in a vacuum to form a polymer.

As specific light emitting layers, cyanopolyphenylene vinylene is used for a light emitting layer emitting red light, polyphenylene vinylene is used for a light emitting layer emitting green light, and polyphenylene vinylene or polyalkylphenylene is used for a light emitting layer emitting blue light. Good. The film thickness is 30-150n
m (preferably 40 to 100 nm).

Typical solvents include toluene, xylene, cymene, chloroform, dichloromethane, γ
Butyl lactone, butyl cellosolve or NMP (N-methyl-2-pyrrolidone) can be mentioned. It is also effective to add an additive for increasing the viscosity of the coating solution.

However, the above example is an example of the organic EL material that can be used as the EL material of the present invention, and it is not necessary to limit the invention to this. Regarding organic EL materials that can be used in the ink jet method, see JP-A-10-012.
All of the materials described in Japanese Patent No. 377 can be cited.

The ink jet system is roughly classified into a bubble jet (registered trademark) system (also referred to as a thermal ink jet system) and a piezo system, and a piezo system is preferable for implementing the present invention. Figure 1 shows the difference between the two.
9 will be described.

FIG. 19A shows an example of the piezo method.
Reference numeral 901 denotes a piezo element (piezoelectric element), 1902 denotes a metal pipe, and 1903 denotes a liquid mixture of an ink material and an EL material (hereinafter, referred to as a liquid mixture).
EL forming solution). When a voltage is applied, the piezoelectric element is deformed, and the metal pipe 1902 is also deformed. As a result, the EL forming solution 1903 inside is emitted as droplets 1904. The application of the EL forming solution is performed by controlling the voltage applied to the piezo element as described above. In this case, EL
Since the forming solution 1903 is extruded by a physical external pressure, there is no influence on the composition or the like.

FIG. 19B shows an example of the bubble jet method, in which 1905 is a heating element, 1906 is a metal pipe,
07 is an EL forming solution. Heating element 190 when energized
5 generates heat, and bubbles 1908 are generated in the EL forming solution 1907. As a result, the bubbles form the EL forming solution 190.
7 are extruded and fired as droplets 1909. The EL forming solution is applied by controlling the current to the heating element in this manner. In this case, since the EL forming solution 1907 is heated by the heating element, it may have an adverse effect depending on the composition of the EL material.

When an EL material is actually applied and formed on the device by using an ink-jet method, an EL layer is formed as shown in FIG. In FIG. 20, reference numeral 91 denotes a pixel portion, 92 and 93 denote drive circuits, and a plurality of pixel electrodes 94 are formed in the pixel portion 91. Although not shown, each pixel electrode is connected to a current control TFT. Further, a bank (see FIG. 1) for individually separating the pixel electrodes 94 is actually provided, but is not shown here.

Then, a red light emitting EL layer 95, a green light emitting EL layer 96, and a blue light emitting
An L layer 97 is formed. At this time, after first forming all the red light emitting EL layers 95, the green light emitting EL layers 96,
An EL layer 97 for emitting blue light may be formed. Also, baking (firing) is performed to remove the solvent contained in the EL forming solution.
Action is required. The baking process may be performed after all the EL layers are formed, or may be performed individually after the formation of the EL layers of each color.

When forming the EL layer, as shown in FIG. 20, a pixel on which a red light emitting EL layer 95 is formed (a pixel corresponding to red) and a pixel on which a green light emitting EL layer 96 is formed ( Pixel corresponding to green) and an EL layer 97 emitting blue light
(Pixels corresponding to blue) are always in a state where the colors are in contact with each other.

Such an arrangement is called a so-called delta arrangement, and is effective for performing good color display. Since the advantage of the ink jet system is that the EL layers of each color can be separately formed, it can be said that the embodiment is most preferably used for an EL display device having a pixel portion in a delta arrangement.

Further, when forming the EL layer 47, it is preferable that the processing atmosphere is a dry atmosphere with a minimum amount of moisture and is performed in an inert gas. Since the EL layer is easily deteriorated by the presence of moisture and oxygen, it is necessary to eliminate such factors as much as possible when forming the EL layer. For example, a dry nitrogen atmosphere, a dry argon atmosphere, or the like is preferable.

After the EL layer 47 is formed by the ink jet method as described above, the cathode 48 and the protective electrode 4 are then formed.
9 is formed. In this specification, a light-emitting element formed by a pixel electrode (anode), an EL layer, and a cathode is referred to as an EL element.

As the cathode 48, magnesium (Mg), lithium (Li), cesium (C
s), a material containing barium (Ba), potassium (K), beryllium (Be), or calcium (Ca) is used. Preferably, MgAg (Mg and Al are Mg: Ag = 1)
An electrode made of a material mixed at 0: 1) may be used. In addition, MgAgAl electrode, LiAl electrode, LiFA
l electrode. The protective electrode 49 is an electrode provided to protect the cathode 48 from external moisture and the like, and is made of a material containing aluminum (Al) or silver (Ag). The protection electrode 49 also has a heat radiation effect.

It is desirable that the EL layer 47 and the cathode 48 are continuously formed in a dried inert atmosphere without being released to the atmosphere. This is because when an organic material is used for the EL layer, it is very weak to moisture, so that it does not absorb moisture when exposed to the atmosphere. Further, it is more preferable to continuously form not only the EL layer 47 and the cathode 48 but also the protective electrode 49 thereon.

Reference numeral 50 denotes a third passivation film having a thickness of 10 nm to 1 μm (preferably 200 to 50 μm).
0 nm). The purpose of providing the third passivation film 50 is mainly to protect the EL layer 47 from moisture, but may have a heat radiation effect similarly to the second passivation film 45. Therefore, the same material as the first passivation film 41 can be used as a forming material. However, in the case where an organic material is used for the EL layer 47, it is preferable that an insulating film from which oxygen is easily released be not used since the EL layer 47 may be deteriorated by bonding with oxygen.

Since the EL layer is weak to heat as described above, it is desirable to form the film at a temperature as low as possible (preferably in a temperature range from room temperature to 120 ° C.). Therefore, it can be said that a plasma CVD method, a sputtering method, a vacuum evaporation method, an ion plating method, or a solution coating method (spin coating method) is a preferable film forming method.

As described above, the second passivation film 45
Is sufficient to suppress the deterioration of the EL element. However, more preferably, the EL element is formed of a two-layer insulating film sandwiching the EL element such as a second passivation film 45 and a third passivation film 50. Surrounded by a film, the intrusion of moisture and oxygen into the EL layer is prevented, the diffusion of alkali metal from the EL layer is prevented, and the accumulation of heat in the EL layer is prevented. As a result, deterioration of the EL layer is further suppressed, and a highly reliable EL display device can be obtained.

Further, the EL display device of the present invention has a pixel portion composed of pixels having a structure as shown in FIG. 1, and TFTs having different structures according to functions are arranged in the pixels. With this, the switching TFT with sufficiently low off current value
In addition, a current controlling TFT resistant to hot carrier injection can be formed in the same pixel, and an EL display device having high reliability and capable of displaying a good image (high operating performance) can be obtained.

Although a multi-gate TFT is used as the switching TFT in the pixel structure of FIG. 1, the configuration such as the arrangement of the LDD region does not need to be limited to the configuration of FIG.

The present invention having the above configuration will be described in more detail with reference to the following embodiments.

[Embodiment 1] FIG. 3 shows an embodiment of the present invention.
This will be described with reference to FIG. Here, a method for simultaneously manufacturing TFTs of a pixel portion and a driving circuit portion provided therearound is described. However, for the sake of simplicity, 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 on a glass substrate 300 to a thickness of 300 nm. In this embodiment, a silicon nitride oxide film is stacked and used as the base film 301. At this time, the nitrogen concentration in contact with the glass substrate 300 is preferably set to 10 to 25 wt%.

It is effective to provide an insulating film made of the same material as the first passivation film 41 shown in FIG. 1 as a part of the base film 301. Current control TFT
Since a large current flows, heat is easily generated, and it is effective to provide an insulating film having a heat radiation effect as close as possible.

Next, an amorphous silicon film (not shown) having a thickness of 50 nm is formed on the base film 301 by a known film forming method. Note that the present invention is not limited to an amorphous silicon film, and may be any semiconductor film including an amorphous structure (including a microcrystalline semiconductor film). Further, a compound semiconductor film having an amorphous structure such as an amorphous silicon germanium film may be used. The film thickness is 2
The thickness may be 0 to 100 nm.

Then, the amorphous silicon film is crystallized by a known technique, and a crystalline silicon film (also called a polycrystalline silicon film or a polysilicon film) 302 is formed. 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, X
Crystallization is performed using excimer laser light using eCl gas.

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

In this embodiment, a crystalline silicon film is used as an active layer of a TFT, but an amorphous silicon film can be used. However, since the current control TFT needs to flow a large current, it is more advantageous to use a crystalline silicon film through which a current can easily flow.

It is effective to form the active layer of the switching TFT for which the off-current needs to be reduced with an amorphous silicon film and the active layer of the current control TFT with a crystalline silicon film. Since the amorphous silicon film has a low carrier mobility, it is difficult for an electric current to flow and an off current is hard to flow. That is, the advantages of both an amorphous silicon film through which a current is hard to flow and a crystalline silicon film through which a current easily flows can be utilized.

Next, as shown in FIG. 3B, a protective film 303 made of a silicon oxide film is
It is formed to a thickness of nm. This thickness is 100-200 nm
(Preferably 130 to 170 nm). Further, any other insulating film containing silicon may be used.
The protective film 303 is provided to prevent the crystalline silicon film from being directly exposed to plasma when adding impurities and to enable fine concentration control.

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

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

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

When activating the impurity element by the laser beam, activation by heat treatment may be used in combination. When activation by heat treatment is performed, heat treatment at about 450 to 550 ° C. may be performed in consideration of the heat resistance of the substrate.

By this step, n-type impurity regions 305, 3
A boundary portion (junction portion) between the end portion 06 and the region around the n-type impurity regions 305 and 306 to which the n-type impurity element is not added becomes clear. This is later explained by TF
When T is completed, it means that the LDD region and the channel forming region can form a very good junction.

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

Next, as shown in FIG.
A gate insulating film 311 is formed to cover the layers 07 to 310.
As the gate insulating film 311, an insulating film containing silicon with a thickness of 10 to 200 nm, preferably 50 to 150 nm may be used. This may have a single-layer structure or a laminated structure. In this embodiment, a 110-nm-thick silicon nitride oxide film is used.

Next, a conductive film having a thickness of 200 to 400 nm is formed and patterned to form gate electrodes 312 to 316. Note that in this embodiment, the gate electrode and a wiring for wiring (hereinafter, referred to as a gate wiring) electrically connected to the gate electrode are formed using different materials. Specifically, a material having lower resistance than 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 does not allow fine processing and has low wiring resistance is used for the gate wiring. 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 is preferably formed as a two-layer or three-layer film as required. As a material for the gate electrode, any known conductive film can be used. However, a material that can be finely processed as described above, specifically, a material that can be patterned into 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) or chromium (Cr), or a nitride film of the above element (typically, Specifically, a tantalum nitride film, a tungsten nitride film, a titanium nitride film), or an alloy film combining the above elements (typically, a Mo-W alloy, a Mo-
A Ta alloy), a silicide film of the above element (typically, a tungsten silicide film, a titanium silicide film), or a silicon film having conductivity can be used. Of course, they may be used as a single layer or stacked.

In this embodiment, a laminated film composed of a 50 nm thick tantalum nitride (TaN) film and a 350 nm thick Ta film is used. This may be formed by a sputtering method. Also,
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 a part of the n-type impurity regions 305 and 306 with the gate insulating film 311 interposed therebetween. This overlapping 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-aligned manner using the gate electrodes 312 to 316 as a mask. The n-type impurity regions 3 are formed in the impurity regions 317 to 323 thus formed.
1/2, 1/10 of 05, 306 (typically 1/3 to
Adjust so that phosphorus is added at a concentration of 1/4). Specifically, a concentration of 1 × 10 ^{16 to} 5 × 10 ¹⁸ atoms / cm ³ (typically, 3 × 10 ^{17 to} 3 × 10 ¹⁸ atoms / cm ³ ) is preferable.

Next, as shown in FIG. 4B, resist masks 324a to 324d are formed so as to cover the gate electrodes and the like, and an n-type impurity element (phosphorus in this embodiment) is added to increase the concentration. The impurity regions 325 to 331 containing phosphorus are formed. Also in this case, the ion doping method using phosphine (PH ₃ ) is performed, and the phosphorus concentration in this region is 1 × 10 ²⁰ to 1
× 10 ²¹ atoms / cm ³ (typically 2 × 10 ^{20 to} 5 × 10
Adjust so as to be ²⁰ atoms / cm ³ ).

In this step, a source region or a drain region of the n-channel TFT is formed. In the switching TFT, a part of the n-type impurity regions 320 to 322 formed in the step of FIG. This remaining region corresponds to the LDD regions 15a to 15d of the switching TFT in FIG.

Next, as shown in FIG. 4C, the resist masks 324a to 324d 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
3 × 10 ²⁰ to 3 × by ion doping using ₂ H ₆ )
10 ²¹ atoms / cm ³ (typically 5 × 10 ²⁰ to 1 × 10 ²¹ a
toms / cm ³ ) Add boron to a concentration.

It should be noted that the impurity regions 333 and 334 have already been doped with phosphorus at a concentration of 1 × 10 ^{16 to} 5 × 10 ¹⁸ atoms / cm ³ , and the boron added here is at least three times as large as that. It is added at a concentration. Therefore, the n-type impurity region formed in advance is completely inverted to P-type and functions as a P-type impurity region.

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

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, causing an increase in resistance and making it difficult to obtain an ohmic contact later. Therefore, the oxygen concentration in the processing atmosphere in the activation step is 1 ppm or less, preferably 0.1 ppm or less.
pm or less.

Next, when the activation step is completed,
A thick gate wiring 335 is formed. As a material of the gate wiring 335, a metal film containing aluminum (Al) or copper (Cu) as a main component (of which composition occupies 50 to 100%) may be used. As for the arrangement, as shown in the gate wiring 211 of FIG.
14 and 315 (corresponding to the gate electrodes 19a and 19b in FIG. 2) 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 the present embodiment is extremely effective in realizing an EL display device having a screen size of 10 inches or more (more preferably 30 inches or more) diagonally.

Next, as shown in FIG. 5A, a first interlayer insulating film 336 is formed. As the first interlayer insulating film 336, an insulating film containing silicon may be used as a single layer or a stacked film obtained by combining them. The film thickness is 400 n
m to 1.5 μm. In this embodiment, 200n
A structure in which a silicon oxide film having a thickness of 800 nm is stacked over a silicon nitride oxide film having a thickness of m is provided.

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

The hydrogenation process is performed for the first interlayer insulating film 336.
May be inserted during formation. That is, a hydrogenation treatment may be performed as described above after a 200-nm-thick silicon nitride oxide film is formed, and then a remaining 800-nm-thick silicon oxide film may be formed.

Next, a contact hole is formed in the first interlayer insulating film 336, and source wirings 337 to 340 are formed.
Drain wirings 341 to 343 are formed. In this embodiment, this electrode is a three-layer laminated film in which a titanium film is formed to a thickness of 100 nm, an aluminum film containing titanium is formed to a thickness of 300 nm, and a titanium film is formed to a thickness of 150 nm. Of course, another conductive film may be used, and an alloy film containing silver, palladium, and copper may be used.

Next, 50 to 500 nm (typically 20 to 500 nm)
The first passivation film 34 with a thickness of
4 is formed. In this embodiment, the first passivation film 3
A silicon nitride oxide film having a thickness of 300 nm is used as 44. This may be replaced by a silicon nitride film. Of course, it is possible to use the same material as the first passivation film 41 of FIG.

Prior to the formation of the silicon oxynitride film, H
_2. It is effective to perform a plasma treatment using a gas containing hydrogen such as NH ₃ . Hydrogen excited by this pretreatment is supplied to the first interlayer insulating film 336, and by performing a heat treatment, the film quality of the first passivation film 344 is improved. At the same time, the hydrogen added to the first interlayer insulating film 336 diffuses to the lower layer side, so that the active layer can be effectively hydrogenated.

Next, the second interlayer insulating film 3 made of an organic resin
47 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 347 has a strong meaning of flattening, acrylic having excellent flatness is preferable. In this embodiment, an acrylic film is formed with a thickness that can sufficiently flatten a step formed by a TFT. The thickness is preferably 1 to 5 μm (more preferably 2 to 4 μm).

Next, 100n is formed on the second interlayer insulating film 347.
An m-thick second passivation film 348 is formed. In this embodiment, since an insulating film containing Si, Al, N, O, and La is used, diffusion of an alkali metal from an EL layer provided thereon can be prevented. At the same time, moisture is prevented from penetrating into the EL layer, and heat generated in the EL layer is dispersed, whereby deterioration of the EL layer and deterioration of the flattening film (second interlayer insulating film) due to heat can be suppressed. .

Then, the second passivation film 348,
Second interlayer insulating film 347 and first passivation film 34
4, a contact hole reaching the drain wiring 343 is formed, and a pixel electrode 349 is formed. In this embodiment, a compound (ITO) film of indium oxide and tin oxide is formed to a thickness of 110 n.
m and patterned to obtain a pixel electrode. This pixel electrode 349 becomes the anode of the EL element. Note that as another material, a compound film of indium oxide and zinc oxide or a zinc oxide film containing gallium oxide can be used.

In this embodiment, the pixel electrode 349 is electrically connected to the drain region 331 of the current controlling TFT via the drain wiring 343. This structure has the following advantages.

The pixel electrode 349 comes into direct contact with an organic material such as an EL layer (light emitting layer) and a charge transport layer.
There is a possibility that mobile ions contained in the L layer and the like diffuse in the pixel electrode. That is, in the structure of this embodiment, the pixel electrode 349 is not directly connected to the drain region 331 which is a part of the active layer, but the relay of the drain wiring 343 can prevent the penetration of mobile ions into the active layer. .

Next, as shown in FIG. 5C, the EL layer 3
The cathode 50 (MgAg electrode) 351 and the protection electrode 35 are formed without exposing to the atmosphere.
Form 2 At this time, it is preferable that heat treatment be performed on the pixel electrode 349 before forming the EL layer 350 and the cathode 351 to completely remove moisture. In addition,
In this embodiment, a MgAg electrode is used as the cathode of the EL element, but another known material may be used.

The EL layer 350

The materials described in the section of the present invention can be used. In this embodiment, as shown in FIG. 21, a hole injection layer (Hole injecting layer) and a hole transport layer (Hole trans
The EL layer has a four-layer structure including a porting layer, a light emitting layer (Emitting layer), and an electron transporting layer (Electron transporting layer). In some cases, the electron transporting layer is not provided, or the electron injecting layer is provided. . In some cases, the hole injection layer may be omitted. Various examples of such combinations have already been reported, and any of these configurations may be used.

As the hole injection layer or the hole transport layer, an amine-based TPD (triphenylamine derivative) may be used. In addition, a hydrazone-based (typically, DEH) or a stilbene-based (typically, STB) is used. ), A star bust system (typically, m-MTDATA) and the like. In particular, a star bust type material having a high glass transition temperature and being difficult to crystallize is preferable. Further, polyaniline (PAni), polythiophene (PEDOT), or copper phthalocyanine (CuPc) may be used.

The light emitting layer used in this embodiment is as follows.
A cyanopolyphenylenevinylene may be used for a red light emitting layer, a polyphenylenevinylene may be used for a green light emitting layer, and a polyphenylenevinylene or a polyalkylphenylene may be used for a blue light emitting layer. The thickness may be 30 to 150 nm (preferably 40 to 100 nm). In this embodiment, toluene is used as a solvent.

Although the protection layer 352 can protect the EL layer 350 from moisture and oxygen, it is more preferable to provide the third passivation film 353. In this embodiment, a silicon nitride film having a thickness of 300 nm is provided as the third passivation film 353. This third passivation film may be formed continuously after the protection electrode 352 without being exposed to the atmosphere. Of course, as the third passivation film 353, the third passivation film 5 of FIG.
The same material as 0 can be used.

The protection electrode 352 is formed of the MgAg electrode 35.
A metal film mainly provided with aluminum is provided in order to prevent the deterioration of No. 1. Of course, other materials may be used. In addition, since the EL layer 350 and the MgAg electrode 351 are extremely weak to moisture, it is desirable to form the protection electrode 352 up to the protection electrode 352 continuously without opening to the atmosphere to protect the EL layer from the outside air.

The EL layer 350 has a thickness of 10 to 400.
nm (typically 60 to 160 nm), MgAg electrode 3
51 has a thickness of 180 to 300 nm (typically 200 to 300 nm).
250 nm). In the case where the EL layer 350 has a stacked structure, the thickness of each layer may be in the range of 10 to 100 nm.

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 the present embodiment has a TF having an optimal structure not only for the pixel portion but also for the drive circuit portion.
By arranging T, very high reliability can be exhibited and operating characteristics can be improved.

First, a TFT having a structure in which hot carrier injection is reduced so as not to reduce the operation speed as much as possible,
N-channel type TFT of CMOS circuit forming drive circuit
Used as 205. Note that the drive circuit here includes a shift register, a buffer, a level shifter, a sampling circuit (transfer gate), and the like. When digital driving is performed, a signal conversion circuit such as a D / A converter may be included.

In the case of this embodiment, as shown in FIG. 5C, the active layer of the n-channel type
5, including a drain region 356, an LDD region 357, and a channel formation region 358. The LDD region 357 overlaps 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 avoid lowering the operation speed.
Further, the n-channel TFT 205 does not need to care much about the off-current value, and it is better to emphasize the operation speed. Therefore, it is desirable that the LDD region 357 be completely overlapped with the gate electrode and the resistance component be reduced as much as possible. That is, it is better to eliminate the so-called offset.

A p-channel type TFT of a CMOS circuit
In 206, since the deterioration due to hot carrier injection is hardly noticeable, an LDD region need not be particularly provided. Of course, it is also possible to provide an LDD region similarly to the n-channel type TFT 205 and take measures against hot carriers.

Note that among the driving circuits, the sampling circuit is a little special as compared with other circuits, and a large current flows in both directions in the channel forming region. That is, the roles of the source region and the drain region are switched. In addition, it is necessary to keep the off-current value as low as possible, and in that sense, it is desirable to arrange a TFT having a function approximately between the switching TFT and the current control TFT.

Therefore, it is desirable to arrange a TFT having a structure as shown in FIG. 9 as the n-channel TFT forming the sampling circuit. As shown in FIG. 9, part of the LDD regions 901a and 901b overlap with the gate electrode 903 with the gate insulating film 902 interposed therebetween. This effect is due to the current control TF
As described in the description of T202, the difference is that in the case of the sampling circuit, the LDD regions 901a and 901b are provided so as to sandwich the channel formation region 904.

Further, a pixel having the structure shown in FIG. 1 is formed to form a pixel portion. Since the structures of the switching TFT and the current control TFT formed in the pixel have already been described with reference to FIG. 1, the description is omitted here.

Actually, when completed up to FIG. 5 (C), use a housing material such as a protective film (laminate film, ultraviolet curable resin film, etc.) having high airtightness or a ceramic sealing can so as not to be further exposed to the outside air. Packaging (encapsulation) is preferred. At this time, the reliability (lifetime) of the EL layer is improved by setting the interior of the housing material to an inert atmosphere or arranging a moisture absorbent (for example, barium oxide) or an antioxidant therein.

When the airtightness is improved by processing such as packaging, a connector (flexible printed circuit: FPC) for connecting terminals routed from elements or circuits formed on the substrate to external signal terminals. To complete the product. Such an EL display device that can be shipped is referred to as an EL module in this specification.

Here, the configuration of the active matrix EL display device of this embodiment will be described with reference to the perspective view of FIG.
The active matrix EL display device of this embodiment includes a pixel portion 602, a gate driver circuit 603, and a source driver circuit 604 formed on a glass substrate 601. The switching TFT 605 of the pixel portion is an n-channel TFT, and is arranged at an intersection of a gate wiring 606 connected to the gate driver circuit 603 and a source wiring 607 connected to the source driver circuit 604. The drain of the switching TFT 605 is connected to the gate of the current control TFT 608.

Further, the source of the current control TFT 608 is connected to the current supply line 609,
The EL element 610 is electrically connected to the drain 8. At this time, if the current controlling TFT 608 is an n-channel TFT, it is preferable that the cathode of the EL element 610 is connected to its drain. The current control TF
When T608 is a p-channel TFT, it is preferable that the drain of the TFT be connected to the anode of the EL element 610.

An FPC 611 serving as an external input terminal
Are provided with input wirings (connection wirings) 612 and 613 for transmitting a signal to the drive circuit and an input wiring 614 connected to the current supply line 609.

FIG. 7 shows an example of a circuit configuration of the EL display device shown in FIG. The EL display device according to this embodiment includes a source-side drive circuit 701 and a gate-side drive circuit (A) 70.
7, a gate side driver circuit (B) 711, and a pixel portion 706. In this specification, a drive circuit is a generic term including a source-side processing circuit and a gate-side drive circuit.

The source-side drive circuit 701 includes a shift register 702, a level shifter 703, a buffer 704, and a sampling circuit (transfer gate) 705. The gate driver circuit (A) 707 includes a shift register 708, a level shifter 709, and a buffer 710. The gate side driver circuit (B) 711 has the same configuration.

Here, the shift registers 702 and 708 have a drive voltage of 5 to 16 V (typically 10 V), and are n-channel TFTs used in a CMOS circuit forming the circuit.
Is suitable for the structure shown by 205 in FIG.

Although the drive voltage of the level shifters 703 and 709 and the buffers 704 and 710 is as high as 14 to 16 V, a CMOS circuit including the n-channel TFT 205 shown in FIG. I have.
It is effective to use a multi-gate structure such as a double gate structure or a triple gate structure for improving the reliability of each circuit.

Although the sampling circuit 705 has a drive voltage of 14 to 16 V, the CMOS circuit including the n-channel TFT 208 shown in FIG. 9 needs to reduce the off-current value in addition to the inversion of the source region and the drain region. Circuit is suitable.

The pixel portion 706 has a drive voltage of 14 to 1
6V, and the pixels having the structure shown in FIG. 1 are arranged.

The above configuration can be easily realized by manufacturing a TFT according to the manufacturing steps shown in FIGS. In this embodiment, only the configuration of the pixel portion and the driving circuit is shown. However, according to the manufacturing process of this embodiment, other components such as a signal dividing circuit, a D / A converter circuit,
It is considered that a logic circuit other than a drive circuit such as an operational amplifier circuit and a gamma correction circuit can be formed over the same substrate, and that a memory portion, a microprocessor, and the like can be formed.

Further, the EL module of this embodiment including the housing material will be described with reference to FIGS. 17 (A) and 17 (B). Note that the reference numerals used in FIGS. 6 and 7 will be referred to as needed.

Substrate (including base film under TFT) 170
0, a pixel portion 1701, a source side driver circuit 1702,
A gate side drive circuit 1703 is formed. Various wirings from the respective drive circuits are input wirings 612 to 614.
Through the FPC 611 to be connected to an external device.

At this time, the housing material 170 is formed so as to surround at least the pixel portion, preferably the driving circuit and the pixel portion.
4 is provided. Note that the housing material 1704 has a shape having a concave portion whose inner size is larger than the outer size of the EL element or a sheet shape, and is fixed to the substrate 1700 by an adhesive 1705 so as to form a closed space together with the substrate 1700. Is done. At this time, the EL element is completely sealed in the closed space, and is completely shut off from the outside air. Note that a plurality of housing members 1704 may be provided.

The material of the housing member 1704 is preferably an insulating material such as glass or polymer. For example, amorphous glass (borosilicate glass, quartz, etc.), crystallized glass,
Examples include ceramic glass, organic resins (acrylic resin, styrene resin, polycarbonate resin, epoxy resin, etc.) and silicone resins. Further, ceramics may be used. If the adhesive 1705 is an insulating substance, a metal material such as a stainless steel alloy can be used.

As the material of the adhesive 1705, an adhesive such as an epoxy resin or an acrylate resin can be used. Further, a thermosetting resin or a photocurable resin can be used as the adhesive. However, it is necessary that the material does not transmit oxygen and moisture as much as possible.

Further, a gap 1706 between the housing material and the substrate 1700 is formed by an inert gas (argon, helium,
Nitrogen or the like). Further, not only gas but also an inert liquid (liquid fluorinated carbon represented by perfluoroalkane or the like) can be used. As the inert liquid, a material as used in JP-A-8-78159 may be used. Further, a resin may be filled.

It is also effective to provide a desiccant in the gap 1706. As a desiccant, JP-A-9-1480
No. 66 can be used. Typically, barium oxide may be used. It is also effective to provide not only a desiccant but also an antioxidant.

Further, as shown in FIG. 17B, a plurality of pixels having individually isolated EL elements are provided in the pixel portion, and all of them have the protection electrode 1707 as a common electrode. In this embodiment, it is preferable that the EL layer, the cathode (MgAg electrode), and the protection electrode are formed continuously without releasing to the atmosphere, but the EL layer and the cathode are formed using the same mask material, and the protection electrode is formed. Only by using another mask material, the structure of FIG. 17B can be realized.

At this time, the EL layer and the cathode need only be provided in the pixel portion, and need not be provided on the driving circuit. Of course, there is no problem even if it is provided on the drive circuit.
Considering that the layer contains an alkali metal, it is preferable not to provide the layer.

The protection electrode 1707 is connected to the input wiring 1709 in a region indicated by 1708. The input wiring 1709 is a wiring for applying a predetermined voltage to the protection electrode 1707, and is connected to the FPC 611 via a conductive paste material (anisotropic conductive film) 1710.

Here, a manufacturing process for realizing the contact structure in the region 1708 will be described with reference to FIGS.

First, according to the steps of this embodiment, FIG.
Get the state of. At this time, the first interlayer insulating film 336 and the gate insulating film 311 are removed at the end of the substrate (the region indicated by 1708 in FIG. 17B), and the input wiring 1709 is formed thereon. Needless to say, it is formed simultaneously with the source wiring and the drain wiring in FIG. (FIG. 18
(A))

Next, when etching the second passivation film 348, the second interlayer insulating film 347 and the first passivation film 344 in FIG. 5B, the region indicated by 1801 is removed and the opening 1802 is removed. To form (FIG. 18 (B))

In this state, in the pixel portion, a step of forming an EL element (a step of forming a pixel electrode, an EL layer, and a cathode) is performed.
At this time, in the region shown in FIG.
The L element is not formed. And the cathode 351
Is formed, a protective electrode 352 is formed using another mask material. Thereby, the protection electrode 352 and the input wiring 170
9 are electrically connected. Further, a third passivation film 353 is provided to obtain a state shown in FIG.

By the above steps, 1708 in FIG.
The contact structure in the region indicated by is realized. The input wiring 1709 is connected to the housing material 1704 and the substrate 1
FPC 61 through a gap between the FPC 61 and the gap 700 (however, the adhesive 1705 is filled with the adhesive 1705. That is, the adhesive 1705 needs to have a thickness that can sufficiently flatten the steps of the input wiring).
Connected to 1. Although the input wiring 1709 has been described here, other output wirings 612 to 614 are similarly connected to the FPC 611 under the housing member 1704.

[Embodiment 2] In this embodiment, an example in which the pixel configuration is different from the configuration shown in FIG.
Shown in

In this embodiment, the two pixels shown in FIG. 2B are arranged symmetrically with respect to the current supply line. That is, as shown in FIG. 10, by sharing the current supply line 213 between two adjacent pixels, the number of required wirings can be reduced. Note that the TFT structure and the like arranged in the pixel may be unchanged.

With such a configuration, it is possible to manufacture a pixel portion with higher definition, and the quality of an image is improved.

The structure of this embodiment can be easily realized according to the manufacturing process of Embodiment 1. For the TFT structure and the like, the description of Embodiment 1 and FIGS.

[Embodiment 3] In this embodiment, a case of forming a pixel portion having a structure different from that of FIG. 1 will be described with reference to FIG. The first embodiment may be followed up to the step of forming the second interlayer insulating film 44. The switching TFT 201 and the current control TF covered with the second interlayer insulating film 44
T202 has the same structure as that of FIG.

In this embodiment, after forming contact holes in the second passivation film 45, the second interlayer insulating film 44, and the first passivation film 41, the pixel electrode 51, the banks 103a and 103b are formed, and then the cathode is formed. 52
And an EL layer 53 is formed. In this embodiment, after the cathode 52 is formed by a vacuum deposition method, the cathode 52 is formed by an ink jet method while maintaining a dried inert atmosphere without opening to the atmosphere.
An L layer 53 is formed. At this time, the banks 103a, 103b
A red light emitting EL layer, a green light emitting EL layer,
A blue light emitting EL layer is formed in separate pixels. Although only one pixel is shown in FIG. 11, pixels having the same structure are formed corresponding to the respective colors of red, green, and blue, whereby color display can be performed. Known materials may be used for the EL layers of these colors.

In this embodiment, as the pixel electrode 51, 150
An aluminum alloy film (an aluminum film containing 1 wt% titanium) having a thickness of nm is provided. Note that any material may be used as the material of the pixel electrode as long as it is a metal material, but a material having high reflectance is preferable. An MgAg electrode having a thickness of 230 nm is used as the cathode 52, and the thickness of the EL layer 53 is 90 nm (from the bottom, the electron transport layer is 20 nm,
0 nm, hole transport layer 30 nm).

Next, a transparent conductive film (in this embodiment, ITO
The anode 54 made of a film is formed to a thickness of 110 nm.
Thus, the EL element 209 is formed. If the third passivation film 55 is formed using the material described in the first embodiment, a pixel having a structure as shown in FIG. 11 is completed.

In the case of the structure of this embodiment, the red, green or blue light generated in each pixel is emitted to the side opposite to the substrate on which the TFT is formed. Therefore, almost the entire area within the pixel, that is, the area where the TFT is formed can be used as an effective light emitting area. As a result, the effective light emitting area of the pixel is significantly improved, and the brightness and contrast ratio (brightness / darkness ratio) of the image are improved.

The structure of this embodiment can be freely combined with any of the structures of the first and second embodiments.

[Embodiment 4] In this embodiment, a case where a pixel having a structure different from that of FIG.
This will be described using (A) and (B).

In FIG. 12A, reference numeral 1201 denotes a switching TFT, which includes an active layer 56 and a gate electrode 57.
a, a gate wiring 57b, a source wiring 58, and a drain wiring 59 are included as components. Also, 1202 is a current control T.
FT, which includes an active layer 60, a gate electrode 61, a source wiring 62, and a drain wiring 63 as components. And
The source wiring 62 of the current controlling TFT 1202 is connected to the current supply line 64, and the drain wiring 63 is connected to the EL element 65. FIG. 12 shows the circuit configuration of this pixel.
(B).

The difference between FIG. 12 (A) and FIG. 2 (A) is that
This is the structure of the switching TFT. In this embodiment, a gate electrode 57a having a thin line width of 0.1 to 5 μm is formed, and an active layer 56 is formed so as to cross the portion. Then, a gate wiring 57b is formed so as to electrically connect the gate electrode 57a of each pixel. This realizes a triple gate structure without taking up much area.

The other parts are the same as those in FIG. 2A. However, when the structure of this embodiment is used, the area occupied by the switching TFT is reduced, so that the effective light emitting area is increased.
That is, the brightness of the image is improved. Further, a gate structure with increased redundancy for reducing an off-current value can be realized, so that image quality can be further improved.

In the structure of this embodiment, the current supply line 64 may be shared between adjacent pixels as in the second embodiment, or may be structured as in the third embodiment. Further, the manufacturing process may be in accordance with the first embodiment.

[Embodiment 5] In the embodiments 1 to 4, the case of the top gate type TFT has been described, but the present invention may be implemented using a bottom gate type TFT. In this embodiment, FIG. 13 shows a case where the present invention is implemented with an inverted staggered TFT. Since the structure other than the TFT structure is the same as that of FIG. 1, the same reference numerals as in FIG. 1 are used as needed.

In FIG. 13, the same material as that of the first embodiment can be used for the substrate 11 and the base film 12. Then, a switching TFT 1301 and a current controlling TFT 1302 are formed on the base film 12.

The structure of the switching TFT 1301 is as follows.
The gate electrodes 70a and 70b, the gate wiring 71, the gate insulating film 72, the source region 73, the drain region 74, the LDD regions 75a to 75d, the high concentration impurity region 76, the channel formation regions 77a and 77b, the channel protection films 78a and 78b, 1
Interlayer insulating film 79, source wiring 80 and drain wiring 81
including.

The configuration of the current controlling TFT 1302 is as follows: the gate electrode 82, the gate insulating film 72, and the source region 8.
3, a drain region 84, an LDD region 85, a channel forming region 86, a channel protective film 87, a first interlayer insulating film 79,
A source wiring 88 and a drain wiring 89 are included. At this time,
The gate electrode 82 is electrically connected to the drain wiring 84 of the switching TFT 1301.

The switching TFT 1301
And a current controlling TFT 1302 is a known inverted staggered TF
What is necessary is just to form by the manufacturing method of T. In addition, the TF
As the material of each part forming T (wiring, insulating film, active layer, etc.), the same material as each corresponding part in the top gate type TFT of the first embodiment can be used. However, a channel protective film 78a not included in the configuration of the top gate type TFT,
The layers 78b and 87 may be formed of an insulating film containing silicon. In addition, as for the formation of the impurity regions such as the source region, the drain region, and the LDD region, the impurity regions may be formed by individually changing the impurity concentrations by using a photolithography technique.

When the TFT is completed, the first passivation film 41, the second interlayer insulating film (flattening film) 44, the second passivation film 45, the pixel electrode (anode) 46, the bank 1
01a, 101b, EL layer 47, MgAg electrode (cathode) 4
8. An aluminum electrode (protective electrode) 49 and a third passivation film 50 are sequentially formed to complete a pixel having the EL element 1303. Embodiment 1 may be referred to for these manufacturing steps and materials.

The structure of this embodiment can be freely combined with any of the structures of Embodiments 2 to 4.

[Embodiment 6] In the structure shown in FIG. 5C or FIG. 1 of the embodiment 1, as a base film provided between the active layer and the substrate, the heat dissipation effect is high similarly to the second passivation film 45. It is effective to use materials. In particular, the current control TFT flows a large amount of current and thus easily generates heat, which may cause deterioration due to self-heating. In such a case, the thermal deterioration of the TFT can be prevented by the heat radiation effect of the base film as in this embodiment.

Of course, since the effect of preventing mobile ions and the like diffused from the substrate is also important, like the first passivation film 41, a laminate of a compound containing Si, Al, N, O, M and an insulating film containing silicon is used. It is also preferred to use a structure.

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

[Embodiment 7] In the case of the pixel structure shown in Embodiment 3, since the light emitted from the EL layer is radiated to the side opposite to the substrate, an insulating film or the like existing between the substrate and the pixel electrode There is no need to worry about the transmittance of the light. That is, a material having a somewhat low transmittance can be used.

Accordingly, it is advantageous to use a carbon film called a diamond thin film, a diamond-like carbon film or an amorphous carbon film as the base film 12, the first passivation film 41 or the second passivation film 45. That is, since there is no need to worry about the decrease in transmittance,
The film thickness can be set as thick as 100 to 500 nm, and the heat radiation effect can be further enhanced.

In the case where the above-mentioned carbon film is used as the third passivation film 50, it is preferable that the film thickness is set to about 5 to 100 nm, since a decrease in transmittance should be avoided.

In this embodiment, the underlayer film 12, the first passivation film 41, and the second passivation film 4 are also used.
Regardless of whether a carbon film is used for the fifth or third passivation film 50, it is effective to use the carbon film laminated with another insulating film.

This embodiment is effective in the case where the pixel structure shown in the third embodiment is used, and the other structures can be freely combined with any of the structures of the first to sixth embodiments.

[Embodiment 8] In the present invention, the off-current value of the switching TFT is reduced by using a multi-gate switching TFT in the pixel of the EL display device, and the necessity of the storage capacitor is eliminated. This is a device for effectively utilizing the area occupied by the storage capacitor as a light emitting region.

However, even if the storage capacity cannot be completely eliminated, the effect of increasing the effective light emitting area can be obtained only by reducing the occupied area. That is, the switching TF
By making T a multi-gate structure, it is sufficient to reduce the off-current value and reduce the area occupied by the storage capacitor.

Therefore, a pixel structure as shown in FIG. 14 can be used. In FIG. 14, the same reference numerals as those in FIG. 1 are cited as necessary.

The difference between FIG. 14 and FIG. 1 is that a storage capacitor 1401 connected to the switching TFT exists. The storage capacitor 1401 is a switching TFT 201
, A semiconductor region (lower electrode) 1402 extending from the drain region 14, a gate insulating film 18, and a capacitor electrode (upper electrode) 1403. The capacitor electrode 1403 is formed simultaneously with the gate electrodes 19a, 19b, and 35 of the TFT.

This top view is shown in FIG. FIG.
FIG. 14 is a cross-sectional view of the top view of FIG. As shown in FIG. 15A, the capacitor electrode 1403 is electrically connected to the source region 31 of the current controlling TFT via the electrically connected connection wiring 1404. Note that the connection wiring 1404 is formed simultaneously with the source wirings 21 and 36 and the drain wirings 22 and 37. FIG.
(B) shows the circuit configuration of the top view shown in FIG.

The structure of this embodiment can be freely combined with any of the structures of Embodiments 1 to 7. That is, only the storage capacitor is provided in the pixel, and TF
It does not limit the material of the T structure or the EL layer.

[Embodiment 9] In Embodiment 1, laser crystallization is used as a means for forming the crystalline silicon film 302. In this embodiment, a case where a different crystallization means is used will be described.

In this embodiment, after forming the amorphous silicon film, crystallization is performed by using the technique described in Japanese Patent Application Laid-Open No. Hei 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.

After the crystallization step is completed, a step of removing the catalyst used for crystallization may be performed. In that case, JP-A-10-270363 or JP-A-8-3
The catalyst may be gettered by the technique described in No. 30602.

Also, Japanese Patent Application No. 11-076 filed by the present applicant.
The TFT may be formed by using the technique described in the specification of US Pat. No. 967.

As described above, the manufacturing process shown in Embodiment 1 is one embodiment, and if the structure shown in FIG. 1 or FIG. There is no problem with using it.

The structure of this embodiment can be freely combined with any of the structures of Embodiments 1 to 8.

[Embodiment 10] In driving the EL display device of the present invention, an analog drive using an analog signal as an image signal or a digital drive using a digital signal can be performed.

In the case of performing the analog driving, an analog signal is sent to the source wiring of the switching TFT, and the analog signal including the gradation information becomes the gate voltage of the current controlling TFT. Then, a current flowing through the EL element is controlled by the current control TFT, and the emission intensity of the EL element is controlled to perform gradation display. . In this case, it is desirable that the current control TFT be operated in a saturation region. That is, | Vds |> | V
It is desirable to operate within the condition of gs−Vth |. Here, Vds is the voltage between the source region and the drain region, Vgs is the voltage between the source region and the gate electrode, Vth
Is the threshold voltage of the TFT.

On the other hand, when digital driving is performed, time-division driving (time gradation driving) is different from analog gradation display.
Alternatively, gradation display called area gradation driving is performed. That is, by adjusting the length of the light emission time and the light emission area ratio,
Visually show that the color gradation has changed. In this case, it is desirable that the current control TFT be operated in a linear region. That is, it is desirable to operate within the condition | Vds | <| Vgs−Vth |.

The EL element has a much higher response speed than the liquid crystal element, and can be driven at a high speed. Therefore, it can be said that the element is suitable for time division driving in which one frame is divided into a plurality of subframes and gradation display is performed. Further, since one frame period is short, the time for holding the gate voltage of the current control TFT is also short, which is advantageous for reducing or omitting the holding capacity.

As described above, since the present invention is a technique relating to the element structure, any driving method may be used.

[Embodiment 11] In this embodiment, the E
Examples of the pixel structure of the L display device are shown in FIGS. In this embodiment, reference numeral 4701 denotes a source wiring of the switching TFT 4702, 4703 denotes a gate wiring of the switching TFT 4702, 4704 denotes a current control TFT, 4705 denotes a current supply line, 4706 denotes a power control TFT, and 4707 denotes a power control TFT. Gate wiring, 4708
Is an EL element. For the operation of the power supply control TFT 4706, refer to Japanese Patent Application No. 11-341272.

In this embodiment, the power supply control TFT 47 is used.
06 is provided between the current control TFT 4704 and the EL element 4708, but the power supply control TFT 4706 and the EL
A current control TFT 4704 may be provided between the element 4708 and the element 4708. Also, the power supply control TFT 47
06 has the same structure as the current control TFT 4704,
It is preferable to form them in series with the same active layer.

FIG. 23A shows an example in which a current supply line 4705 is shared between two pixels. That is,
It is characterized in that two pixels are formed so as to be line-symmetric about the current supply line 4705. In this case, the number of current supply lines can be reduced, so that the pixel portion can have higher definition.

FIG. 23B shows a gate wiring 470.
A current supply line 4710 is provided in parallel with
This is an example in the case where a power supply control gate wiring 4711 is provided in parallel with the line 01. Note that the current supply line 47 is shown in FIG.
Although the structure is such that 10 and the gate wiring 4703 are provided so as not to overlap with each other, the wiring may be provided so as to overlap with an insulating film interposed therebetween as long as they are formed in different layers. In this case, the current supply line 4710 and the gate wiring 47
03 can share the occupied area, so that the pixel portion can be further refined.

[Embodiment 12] In this embodiment, the E of the present invention will be described.
FIGS. 24A and 24B show examples of the pixel structure of the L display device. In this embodiment, reference numeral 4801 denotes a source wiring of the switching TFT 4802, 4803 denotes a gate wiring of the switching TFT 4802, 4804 denotes a current control TFT, 4805 denotes a current supply line, and 4806 denotes an erasing T.
FT, 4807 is an erasing gate wiring, and 4808 is an EL element. For the operation of the erasing TFT 4806, refer to Japanese Patent Application No. 11-338786.

The drain of the erasing TFT 4806 is connected to the gate of the current controlling TFT 4804,
The gate voltage of the FT4804 can be forcibly changed. The erasing TFT 4806
May be an n-channel TFT or a p-channel TFT, but preferably has the same structure as the switching TFT 4802 so that off-state current can be reduced.

FIG. 24A shows an example in which the current supply line 4805 is shared between two pixels. That is,
It is characterized in that two pixels are formed to be line-symmetric with respect to the current supply line 4805. In this case, the number of current supply lines can be reduced, so that the pixel portion can have higher definition.

FIG. 24B shows a gate wiring 480.
3, a current supply line 4810 is provided in parallel with the source line 48.
This is an example in which an erasing gate wiring 4811 is provided in parallel with the line 01. Note that in FIG. 24B, the current supply line 4810
The gate wiring 4803 and the gate wiring 4803 are provided so as not to overlap with each other. However, as long as the wiring is formed in a different layer, the wiring may be provided so as to overlap with an insulating film therebetween. In this case, the current supply line 4810 and the gate wiring 480
3 can share an occupied area, so that the pixel portion can be further refined.

[Embodiment 13] The EL display device of the present invention may have a structure in which any number of TFTs are provided in a pixel. Embodiments 11 and 12 show an example in which three TFTs are provided, but four to six TFTs may be provided. The present invention can be implemented without being limited to the pixel structure of the EL display device.

[Embodiment 14] In this embodiment, an example in which a p-channel TFT is used as the current control TFT 202 of FIG. 1 will be described. Other parts are shown in FIG.
Therefore, detailed description is omitted.

FIG. 25 shows a sectional structure of a pixel of this embodiment. Embodiment 1 can be referred to for a method for manufacturing a p-channel TFT used in this embodiment. The active layer of the p-channel TFT includes a source region 2801, a drain region 2802, and a channel formation region 2803, and the source region 280
1 is connected to the source wiring 36, and the drain region 2802 is connected to the drain wiring 37.

As described above, when the anode of the EL element is connected to the current controlling TFT, p
It is preferable to use a channel type TFT.

The structure of this embodiment is similar to those of the first to thirteenth embodiments.
Can be freely combined with any of the above configurations.

[Embodiment 15] In the present invention, by using an EL material capable of utilizing phosphorescence from triplet excitons for light emission, external light emission quantum efficiency can be remarkably improved. Thus, low power consumption, long life, and light weight of the EL element can be achieved. Here, a report is shown in which the triplet exciton is used to improve the external emission quantum efficiency.
(T.Tsutsui, C.Adachi, S.Saito, Photochemical Proce
sses in Organized Molecular Systems, ed.K. Honda,
(Elsevier Sci. Pub., Tokyo, 1991) p.437.) The molecular formula of the EL material (coumarin dye) reported in the above paper is shown below.

[0252]

Embedded image

(MABaldo, DFO'Brien, Y. You, A. Shou
stikov, S. Sibley, METhompson, SRForrest, Natur
e 395 (1998) p.151.) The molecular formula of the EL material (Pt complex) reported in the above article is shown below.

[0254]

Embedded image

(MABaldo, S. Lamansky, PEBurrrows,
METhompson, SRForrest, Appl.Phys.Lett., 75 (199
9) p.4.) (T.Tsutsui, M.-J.Yang, M.Yahiro, K.Nakamura, T.Wat
anabe, T.tsuji, Y.Fukuda, T.Wakimoto, S.Mayaguchi,
Jpn. Appl. Phys., 38 (12B) (1999) L1502.) The molecular formula of the EL material (Ir complex) reported in the above paper is shown below.

[0256]

Embedded image

As described above, if the phosphorescence emission from the triplet exciton can be used, it is possible in principle to realize an external emission quantum efficiency three to four times higher than the case where the fluorescence emission from the singlet exciton is used. . Note that the configuration of this embodiment is the same as that of Embodiments 1 to
The present invention can be implemented by freely combining with any configuration of the thirteenth embodiment.

[Embodiment 16] In the first embodiment, it is preferable to use an organic EL material for the EL layer. However, the present invention can be implemented by using an inorganic EL material. However, since a current inorganic EL material has a very high driving voltage, a TFT having a withstand voltage characteristic capable of withstanding such a driving voltage must be used in performing analog driving.

Alternatively, if an inorganic EL material having a further lower driving voltage is developed in the future, it can be applied to the present invention.

The structure of this embodiment is similar to that of the first to fourteenth embodiments.
Any configuration can be freely combined.

[Embodiment 17] An active matrix EL display device (EL module) formed by carrying out the present invention is of a self-luminous type, and therefore has excellent visibility in a bright place compared to a liquid crystal display device. I have. Therefore, direct-view EL
It is widely used as a display (refers to a display incorporating an EL module).

[0262] One of the advantages of the EL display over the liquid crystal display is the wide viewing angle. Therefore, to watch TV broadcasts on a large screen, the diagonal 3
The EL display of the present invention may be used as a display (display monitor) of 0 inches or more (typically, 40 inches or more).

Further, the present invention can be used not only as an EL display (a personal computer monitor, a TV broadcast reception monitor, an advertisement display monitor, etc.) but also as a display for various electronic devices.

As such an electronic device, a video camera, a digital camera, a goggle type display (head mounted display), a car navigation, a personal computer, a portable information terminal (a mobile computer, a mobile phone or an electronic book, etc.), and a recording medium are used. Equipped image reproducing device (specifically, compact disc (CD),
A device that reproduces a recording medium such as a laser disk (registered trademark) (LD) or a digital video disk (DVD) and has a display capable of displaying an image thereof). FIG. 16 shows examples of these electronic devices.

FIG. 16A shows a personal computer, which includes a main body 2001, a housing 2002, a display portion 2003,
And a keyboard 2004. The present invention can be used for the display portion 2003.

FIG. 16B shows a video camera, which includes a main body 2101, a display portion 2102, an audio input portion 2103, operation switches 2104, a battery 2105, and an image receiving portion 210.
6 inclusive. The present invention can be used for the display portion 2102.

FIG. 16C shows a goggle type display, which includes a main body 2201, a display portion 2202, and an arm portion 220.
3 inclusive. The present invention can be used for the display portion 2202.

FIG. 16D shows a portable computer, which includes a main body 2301, a camera section 2302, an image receiving section 2303, operation switches 2304, and a display section 2305. The present invention can be used for the display portion 2305.

FIG. 16E shows an image reproducing apparatus (specifically, a DVD reproducing apparatus) provided with a recording medium.
1, recording medium (CD, LD, DVD, etc.) 2402,
An operation switch 2403, a display unit (a) 2404, and a display unit (b) 2405 are included. The display section (a) mainly displays image information, and the display section (b) mainly displays character information. The present invention can be used for these display sections (a) and (b). Note that the present invention can be applied to a CD playback device, a game machine, and the like as an image playback device provided with a recording medium.

FIG. 16F shows an EL display.
A housing 2501, a support 2502, and a display unit 2503 are included. The present invention can be used for the display portion 2503. The EL display of the present invention is particularly advantageous when the screen is enlarged, and is advantageous for a display having a diagonal of 10 inches or more (particularly a diagonal of 30 inches or more).

Further, if the emission luminance of the EL material is increased in the future, it can be used for a front type or rear type projector.

In addition, the above-mentioned electronic device can be connected to the Internet or C
Information distributed through an electronic communication line such as an ATV (cable television) is frequently displayed, and in particular, opportunities to display moving image information are increasing. Since the response speed of the EL material is very high, it is suitable for displaying such a moving image.

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

FIG. 22A shows a portable telephone, which includes a main body 2601, an audio output unit 2602, and an audio input unit 260.
3, including a display unit 2604, operation switches 2605, and an antenna 2606. The EL display device of the present invention has a display section 260.
4 can be used. Note that the display portion 2604 can display power of the mobile phone by displaying white characters on a black background.

FIG. 22B shows a vehicle-mounted audio system (car audio system).
02, including operation switches 2703 and 2704. The EL display device of the present invention can be used for the display portion 2702. In this embodiment, the in-vehicle audio is shown, but it may be used for stationary audio. The display unit 27
No. 02 can suppress power consumption by displaying white characters on a black background.

As described above, the applicable range of the present invention is extremely wide, and can be applied to electronic devices in all fields. Further, the electronic device of the present embodiment can be realized by using a configuration composed of any combination of Embodiments 1 to 16.

[0277]

According to the present invention, the EL element can be prevented from being deteriorated by moisture or heat. Further, it is possible to prevent the alkali metal from diffusing from the EL layer and adversely affecting the TFT characteristics. As a result, EL
The operation performance and reliability of the display device can be significantly improved.

By providing such an EL display device as a display, it is possible to produce a durable (highly reliable) applied product (electronic device) having good image quality.

[Brief description of the drawings]

FIG. 1 illustrates a cross-sectional structure of a pixel portion of an EL display device.

FIG. 2 is a diagram showing a top structure and a structure of a pixel portion of an EL display device.

FIG. 3 illustrates a manufacturing process of an active matrix EL display device.

FIG. 4 illustrates a manufacturing process of an active matrix EL display device.

FIG. 5 illustrates a manufacturing process of an active matrix EL display device.

FIG. 6 is a diagram illustrating an appearance of an EL module.

FIG. 7 is a diagram showing a circuit block configuration of an EL display device.

FIG. 8 is an enlarged view of a pixel portion of an EL display device.

FIG. 9 illustrates an element structure of a sampling circuit of an EL display device.

FIG. 10 illustrates a structure of a pixel portion of an EL display device.

FIG. 11 illustrates a cross-sectional structure of a pixel portion of an EL display device.

FIG. 12 illustrates a top structure and a structure of a pixel portion of an EL display device.

FIG. 13 illustrates a cross-sectional structure of a pixel portion of an EL display device.

FIG. 14 illustrates a cross-sectional structure of a pixel portion of an EL display device.

FIG. 15 is a diagram showing a top structure and a structure of a pixel portion of an EL display device.

FIG. 16 illustrates a specific example of an electronic device.

FIG. 17 illustrates an appearance of an EL module.

FIG. 18 is a diagram showing a manufacturing process of a contact structure.

FIG. 19 is a diagram illustrating an ink jet system.

FIG. 20 is a diagram showing EL layer formation by an inkjet method.

FIG. 21 illustrates a stacked structure of an EL layer.

FIG. 22 illustrates a specific example of an electronic device.

FIG. 23 illustrates a circuit configuration of a pixel portion of an EL display device.

FIG 24 illustrates a circuit configuration of a pixel portion of an EL display device.

FIG. 25 illustrates a cross-sectional structure of a pixel portion of an EL display device.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05B 33/22 H05B 33/22 Z (72) Inventor Toshimitsu Onuma 398 Hase, Atsugi-shi, Kanagawa Pref. Energy Research Institute

Claims (12)

[Claims] A step of forming a plurality of TFTs on a substrate; a step of forming a plurality of pixel electrodes connected to each of the plurality of TFTs; and forming an EL layer on the plurality of pixel electrodes. A method for manufacturing an electro-optical device, comprising: a step of selectively forming the EL layer by an inkjet method. 2. A step of forming a plurality of TFTs on a substrate; a step of forming a plurality of pixel electrodes connected to each of the plurality of TFTs; and forming an EL layer on the plurality of previous pixel electrodes. And a step of forming the EL layer, wherein the EL layer is selectively formed corresponding to each of the plurality of pixel electrodes by an inkjet method. A step of forming a plurality of TFTs on the substrate; a step of forming a plurality of pixel electrodes connected to each of the plurality of TFTs; Forming an EL layer that emits red light on the provided pixel electrode; and forming an EL layer that emits green light on a pixel electrode provided for a pixel corresponding to green among the plurality of pixel electrodes. A step of forming an EL layer that emits blue light on a pixel electrode provided in a pixel corresponding to blue among the plurality of pixel electrodes, wherein the EL layer emits red, green, or blue light. The method for manufacturing an electro-optical device, wherein the layer is selectively formed by an inkjet method. 4. A step of forming a plurality of TFTs on a substrate, a step of forming an insulating film covering the plurality of TFTs, forming an opening in the insulating film, and connecting to each of the plurality of TFTs. Forming a plurality of formed pixel electrodes, and selectively forming an EL layer on the plurality of previous pixel electrodes by an ink-jet method, wherein the uppermost layer of the insulating film transmits alkali metal. A method for manufacturing an electro-optical device, comprising using an insulating film that can hinder the operation. 5. A step of forming a plurality of TFTs on a substrate, a step of forming an insulating film covering the plurality of TFTs, forming an opening in the insulating film, and connecting to each of the plurality of TFTs. Forming a plurality of pixel electrodes, and a step of selectively forming an EL layer on each of the plurality of pixel electrodes by an ink-jet method on the plurality of previous pixel electrodes, A method for manufacturing an electro-optical device, wherein an insulating film capable of preventing alkali metal from permeating is used as an uppermost layer of the insulating film. 6. A step of forming a plurality of TFTs on a substrate, a step of forming an insulating film covering the plurality of TFTs, forming an opening in the insulating film, and connecting to each of the plurality of TFTs. Forming a plurality of formed pixel electrodes; forming an EL layer that emits red light on a pixel electrode provided in a pixel corresponding to red among the plurality of pixel electrodes; Forming an EL layer that emits green light on a pixel electrode provided for a pixel corresponding to green among the plurality of pixel electrodes; and forming a blue color on a pixel electrode provided for a pixel corresponding to blue among the plurality of pixel electrodes. Forming an EL layer that emits red light, green light, or blue light. The EL layer that emits red, green, or blue light is selectively formed by an inkjet method. An insulating film that can interfere Method for manufacturing an electro-optical device, characterized in that. 7. The pixel according to claim 3, wherein the pixel corresponding to red, the pixel corresponding to green, and the pixel corresponding to blue are formed such that the respective colors are always in contact with each other. Of manufacturing an electro-optical device. 8. The EL device according to claim 1, wherein
The method for manufacturing an electro-optical device, wherein the layer is an organic material. 9. A method for manufacturing an electro-optical device according to claim 1, wherein said ink jet system uses a piezo element. 10. An electro-optical device according to claim 1, wherein said insulating film is formed by laminating an insulating film capable of preventing permeation of said alkali metal on an organic resin film. Method of manufacturing. 11. The insulating film according to claim 1, wherein at least one of B (boron), C (carbon), and N (nitrogen) is used as the insulating film capable of preventing permeation of the alkali metal. Elements, Al (aluminum), S
A method for manufacturing an electro-optical device, comprising using an insulating film containing at least one element selected from i (silicon) and P (phosphorus). 12. An insulating film according to claim 1, wherein said insulating film capable of preventing permeation of said alkali metal contains Si, Al, N, O and M (where M is a rare earth element). At least one, preferably Ce (cerium), Yb (ytterbium), Sm (samarium),
An electro-optical device characterized in that Er (erbium), Y (yttrium), La (lanthanum), Gd (gadolinium), Dy (dysprosium), or Nd (neodymium) is used. Production method.