JP4408118B2 - Display device - Google Patents

Description

The present invention is an EL formed by forming a semiconductor element (an element using a semiconductor thin film) on a substrate.
(Electroluminescence) The present invention relates to an electro-optical device typified by a display device and an electronic device (electronic device) having the electro-optical device as a display display (also referred to as a display unit).

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

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

In an active matrix EL display device, each pixel is provided with a switching element made of a TFT, and a driving element that performs current control is operated by the switching element.
The layer (light emitting layer) is caused to emit light. At this time, a typical pixel structure is, for example, US Pat.
4, 365 (JP-A-8-234683). 1 is disclosed.

FIG. As shown in FIG. 1, the drain of the switching element (T1) is connected to the gate electrode of the current control element (T2).
s). The electric charge stored in the capacitor (Cs) is used to control the current control element (
The gate voltage of T2) is maintained.

Conversely, when the switching element (T1) is in a non-selection state, if there is no capacitor (Cs), charge leaks through the switching element (T1) (current flowing at this time is referred to as off-current), and the current control element The voltage applied to the gate electrode of (T2) cannot be maintained.
This is an unavoidable problem in forming the switching element (T1) with a transistor. However, since this capacitor (Cs) is provided in the pixel, it has been a factor of narrowing the effective light emission area (effective image display area) of the pixel.

The current control element (T2) needs to pass a large current in order to cause the EL layer to emit light.
That is, the performance required for the TFT is completely different between the switching element and the current control element. In such a case, it is difficult to ensure the performance required for all circuits or elements with only the TFTs having the same structure.

SUMMARY An advantage of some aspects of the invention is that it provides an electro-optical device, particularly an EL display device, which has high operation performance and high reliability. An electronic device (electronic device) having an electro-optical device as a display by improving the image quality
The issue is to improve the quality of the product.

In order to achieve the above object, in the present invention, an optimally structured TFT is assigned in view of the function required by an element included in each pixel of an EL display device. That is, TFTs having different structures exist in the same pixel.

Specifically, an element (such as a switching element) whose primary priority is to sufficiently reduce the off-current value is a TFT structure that focuses on reducing the off-current value rather than the operating speed. For the elements that are most important to flow (such as current control elements), rather than reducing the off-current value, suppress the deterioration caused by hot carrier injection, which causes a significant current flow at the same time. TFT structure with emphasis on.

In the present invention, by properly using the TFT as described above on the same substrate, it is possible to improve the operation performance and reliability of the EL display device. Note that the idea of the present invention is not limited to the pixel portion, but is also characterized in that the TFT structure is optimized including the pixel portion and a drive circuit portion for driving the pixel portion.

By using the present invention, on the same substrate, TFT with appropriate performance according to the specifications required by the element
Can be formed, and the operation performance and reliability of the active matrix EL display device can be greatly improved.

In addition, by having such an EL display device as a display display, it is possible to produce an application product (electronic device) having good image quality and durability (high reliability).

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).

Note that the cross-sectional view of FIG. 1 shows a cut surface cut along AA ′ in the top view shown in FIG. Here, since the same reference numerals are used in FIG. 1 and FIG. Moreover, although two pixels are illustrated in the top view of FIG. 2, both have the same structure.

In FIG. 1, 11 is a substrate and 12 is 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 conductive substrate is used, but it need not be provided on the quartz substrate. As the base film 12, an insulating film containing silicon may be provided. Note that in this specification, the “insulating film containing silicon” specifically includes silicon, oxygen, or nitrogen such as a silicon oxide film, a silicon nitride film, or a silicon nitride oxide film (indicated by SiOxNy) at a predetermined ratio. An insulating film.

Here, two TFTs are formed in the pixel. Reference numeral 201 denotes a TFT that functions as a switching element (hereinafter referred to as a switching TFT), and 202 denotes a TFT that functions as a current control element that controls the amount of current flowing to the EL element (hereinafter referred to as a current control TFT). Is also formed of an n-channel TFT.

Since the field effect mobility of the n-channel TFT is larger than that of the p-channel TFT, the operation speed is fast and it is easy to flow current. Even when the same amount of current flows, the n-channel TFT can be made smaller in TFT size. Therefore, it is preferable to use an n-channel TFT as a current control TFT because the effective area of the display portion is widened.

The p-channel TFT has the advantage that hot carrier injection is hardly a problem and has a low off-current value, 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, the present invention solves the problem of hot carrier injection and the problem of off-current value even in the n-channel TFT by adopting a structure where the positions of the LDD regions are different, and all the TFTs in all the pixels are n-channel type. Another characteristic is that it is a TFT.

In the present invention, however, the switching TFT and the current control TFT are n-channel type T
It is not necessary to limit to FT, and p-channel TFTs can be used for both or one of them.

The switching TFT 201 includes a source region 13, a drain region 14, and an LDD region 15.
a to 15d, an active layer including the high-concentration impurity region 16 and the channel formation regions 17a and 17b, a gate insulating film 18, gate electrodes 19a and 19b, a first interlayer insulating film 20, a source wiring 21 and a drain wiring 22; It is formed.

As shown in FIG. 2, the present invention is characterized in that the gate electrodes 19a and 19b are made of different materials (gate electrode 19).
a material having a lower resistance than a and 19b), and a double gate structure in which the gate wiring 211 is electrically connected. Needless to say, not only a double gate structure but also a so-called multi-gate structure such as a triple gate structure (a structure including an active layer having two or more channel formation regions connected in series) may be used. The multi-gate structure is extremely effective in reducing the off-current value. In the present invention, the switching TFT 201 of the pixel has a multi-gate structure, thereby realizing a switching TFT having a low off-current value.

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

Further, in the switching TFT 201, the LDD regions 15a to 15d are provided so as not to overlap the gate electrodes 19a and 19b with the gate insulating film 18 interposed therebetween. Such a structure is very effective in reducing the off-current value.

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

As described above, in the present invention, a TFT having a multi-gate structure is used as a pixel switching TFT 2.
By using it as 01, there is a feature in realizing a switching element having a sufficiently low off-state current value. Therefore, the gate voltage of the current control element can be maintained for a sufficient time (between the selection and the next selection) without providing the capacitor (Cs) as described in the conventional example.

That is, it is possible to eliminate a capacitor that has been a factor for reducing the effective light emitting area in the past, and to increase the effective light emitting area. This means that the image quality of the EL display device can be brightened.

Next, the current control TFT 202 includes a source region 31, a drain region 32, and an LDD region 3.
3 and an active layer including a channel formation region 34, a gate insulating film 18, a gate electrode 35, a first interlayer insulating film 20, a source 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 drain of the switching TFT 201 is the current control TFT 202.
Is electrically connected to the gate. Specifically, the gate electrode 3 of the current control TFT 202
5 is electrically connected to the drain region 14 of the switching TFT 201 via a drain wiring (also referred to as connection wiring) 22. The source wiring 36 is connected to the current supply line 212.

The current control TFT 202 is characterized in that the channel width is larger than the channel width of the switching TFT 201. That is, as shown in FIG. 8, when the channel length of the switching TFT is L1, the channel width is W1, the channel length of the current control TFT is L2, and the channel width is W2, W2 / L2 ≧ 5 × W1 / L1 (preferably W2 / L2 ≧ 10 × W1
/ L1) is established. For this reason, it is possible to easily flow more current than the switching TFT.

Note that the channel length L1 of the switching TFT having a multi-gate structure is the sum of the channel lengths of two or more formed channel formation regions. In the case of FIG. 8, since it has a double gate structure, each of the channel lengths L1a and L1b of the two channel formation regions.
The channel length L1 of the switching TFT is added.

In the present invention, the channel lengths L1 and L2 and the channel widths W1 and W2 are not limited to specific numerical ranges, but W1 is 0.1 to 5 μm (typically 1 to 3 μm), and W2 is 0.
The thickness is preferably 5 to 30 μm (typically 2 to 10 μm). At this time, L1 is 0.2-1
8 μm (typically 2 to 15 μm) and L2 are preferably 0.1 to 50 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 an excessive current flow. Preferably W2 / L2 ≧ 3 (preferably W2 / L2
≧ 5). Desirably 0.5-2 μA per pixel (preferably 1-1.5
μA).

By setting these numerical ranges, the EL display device having the number of pixels of the VGA class (640 × 480) to the number of pixels of the high vision class (1920 × 1080 or 1280 × 10).
All standards up to EL display devices having 24) can be covered.

The length (width) of the LDD region formed in the switching TFT 201 is 0.5-3.
. What is necessary is just to set it as 5 micrometers, typically 2.0-2.5 micrometers.

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

The current control TFT 202 supplies a current for causing the EL element 203 to emit light, and at the same time controls the supply amount to enable gradation display. For this reason, it is necessary to take measures against deterioration by hot carrier injection so as not to deteriorate even when a current is passed. In addition, when displaying black, the current control TFT 202 is turned off. However, if the off-current value is high, a clear black display cannot be obtained, resulting in a decrease in contrast. Therefore, it is necessary to suppress the off-current value.

Regarding 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 overlaid on the gate electrode, the off-current value increases. Therefore, the applicant has a novel structure in which LDD regions that do not overlap with the gate electrode are provided in series, thereby preventing hot carriers and off-current. It solves value measures 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 μm).
To 1.5 μm). If it 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 may be 1.0 to 3.5 μm (preferably 1.5 to 2.0 μm). If it is too long, it will not be possible to pass a sufficient current, and if it is too short, the effect of reducing the off-current value will be weak.

Further, in the above structure, a parasitic capacitance is formed in a region where the gate electrode and the LDD region overlap with each other. Therefore, it is preferable not to provide between the source region 31 and the channel formation region 34. Since the current control TFT always has the same direction of carrier (electrons) flow, it is sufficient to provide an LDD region only on the drain region side.

Further, from the viewpoint of increasing the amount of current that can be passed, the thickness of the active layer (especially the channel formation region) of the current control TFT 202 may be increased (preferably 50 to 100 nm, more preferably 60 to 80 nm). It is valid. Conversely, in the case of the switching TFT 201, from the viewpoint of reducing the off-current value, the thickness of the active layer (especially the channel formation region) should be reduced (preferably 20 to 50 nm, more preferably 25 to 40 nm). Is also effective.

Next, reference numeral 41 denotes a first passivation film having a film thickness of 10 nm to 1 μm (preferably 2).
(00 to 500 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 contaminants and moisture. The EL layer finally provided above the TFT contains an alkali metal such as sodium. That is, the first passivation film 41 functions as a protective layer that prevents these alkali metals (movable ions) from entering the TFT side. In this specification, the term “alkali metal” includes alkali metals and alkaline earth metals.

It is also effective to prevent thermal degradation of the EL layer by providing the passivation film 41 with a heat dissipation effect. However, since the EL display device having the structure shown in FIG. 1 emits light toward the substrate 11, the passivation film 41 needs to have translucency.

As a translucent material having a heat dissipation effect, at least one element selected from B (boron), C (carbon), and N (nitrogen), and Al (aluminum), Si (silicon), and P (phosphorus) are used. Examples include compounds containing at least one selected element. For example, aluminum nitride (
Aluminum nitride typified by AlxNy), silicon carbide typified by silicon carbide (SixCy), silicon nitride typified by silicon nitride (SixNy), boron nitride (BxN)
Boron nitrides represented by y) and boron phosphides represented by boron phosphide (BxPy) can be used. An aluminum oxide typified by aluminum oxide (AlxOy) is excellent in light-transmitting property and has a thermal conductivity of 20 Wm ⁻¹ K ⁻¹ and can be said to be one of preferable materials. These materials have not only a heat dissipation effect but also an effect of preventing intrusion of moisture, alkali metals, and the like. In the translucent material, x and y are arbitrary integers.

In addition, another element can also be combined with the said compound. For example, it is possible to use aluminum nitride oxide represented by AlNxOy by adding nitrogen to aluminum oxide. This material has not only a heat dissipation effect but also an effect of preventing moisture, alkali metal and the like from entering. In the aluminum nitride oxide, x and y are arbitrary integers.

Moreover, the material described in Unexamined-Japanese-Patent No. 62-90260 can be used. That is,
A compound containing Si, Al, N, O, and M (where M is at least one rare earth element, preferably Ce (cerium), Yb (ytterbium), Sm (samarium), Er (erbium), Y (yttrium), It is also possible to use at least one element selected from La (lanthanum), Gd (gadolinium), Dy (dysprosium), and Nd (neodymium). These materials have not only a heat dissipation effect but also an effect of preventing intrusion of moisture, alkali metals, and the like.

Further, a carbon film such as a diamond thin film or amorphous carbon (especially, a material having characteristics close to diamond, called diamond-like carbon) can be used. These have very high thermal conductivity and are extremely effective as a heat dissipation layer. However, as the film thickness increases, the film becomes brownish and the transmittance decreases. Therefore, 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 contaminants and moisture, it should not impair the effect. Accordingly, a thin film made of a material having the above heat dissipation effect can be used alone, but these thin films and a thin film (typically a silicon nitride film (SixNy) or oxynitrided oxide) having a property of blocking alkali metals and moisture. It is effective to stack a silicon film (SiOxNy). Note that in the silicon nitride film or the silicon nitride oxide film, x and y are arbitrary integers.

Reference numeral 42 denotes a color filter, and 43 denotes a phosphor (also referred to as a fluorescent dye layer). Both are combinations of the same color and include red (R), green (G) or blue (B) pigments. The color filter 42 is provided to improve color purity, and the phosphor 43 is provided to perform color conversion.

The EL display device is roughly divided into four color display methods, a method of forming three types of EL elements corresponding to RGB, a method of combining a white light emitting EL element and a color filter, and blue or blue-green. There are a method in which a light emitting EL element and a phosphor (fluorescent color conversion layer: CCM) are combined, and a method in which EL elements corresponding to RGB are stacked using a transparent electrode as a cathode (counter electrode).

The structure of FIG. 1 is an example in the case of using a method in which a blue light emitting EL element and a phosphor are combined. Here, light having a wavelength in a blue region including ultraviolet light is formed using a light emitting layer that emits blue light as the EL element 203, and the phosphor 43 is excited by the light to generate red, green, or blue light. Then, the color filter 42 increases the color purity and outputs the result.

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

Further, after the color filter 42 and the phosphor 43 are formed, the second interlayer insulating film 44 is planarized. The second interlayer insulating film 44 is preferably a resin film, such as polyimide, polyamide,
Acrylic, BCB (benzocyclobutene), or the like is preferably used. Of course, an inorganic film may be used if sufficient planarization is possible.

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

It is also effective to provide an insulating film having a high heat dissipation effect (hereinafter referred to as a heat dissipation layer) on the second interlayer insulating film 44. The film thickness is preferably 5 nm to 1 μm (typically 20 to 300 nm).
Such a heat dissipation layer functions to release heat generated in the EL element and prevent the heat from being accumulated in the EL element. Further, when the second interlayer insulating film 44 is a resin film, since it is vulnerable to heat, heat generated in the EL element is prevented from adversely affecting the second interlayer insulating film 44.

As described above, it is effective to planarize a TFT with a resin film in manufacturing an EL display device. However, there has been no structure that takes into account deterioration of a resin film due to heat generated in an EL element.
Therefore, it can be said that it is very effective to solve this problem by providing a heat dissipation layer.

Further, if a material that does not transmit moisture, oxygen, or alkali metal (a material similar to the first passivation film 41) is used for the heat dissipation layer, the EL element or the resin film is prevented from being deteriorated by the heat, and at the same time, It also functions as a protective layer for preventing the alkali metal from diffusing to the TFT side. Furthermore, it functions as a protective layer that prevents moisture and oxygen from entering the EL layer side from the TFT side.

In particular, if a heat dissipation effect is expected, a carbon film such as a diamond film or a diamond-like carbon film is preferable, and a laminated structure of a carbon film and a silicon nitride film (or silicon nitride oxide film) is used to prevent intrusion of moisture and the like. Further preferred.

Thus, a structure in which the TFT side and the EL element side are separated by an insulating film that has a high heat radiation effect and can block moisture and alkali metal is effective.

Reference numeral 45 denotes a pixel electrode (EL element anode) made of a transparent conductive film, and the second interlayer insulating film 4.
4 and the first passivation film 41, a contact hole is opened, and then the current control TFT 2
It is formed so as to be connected to the 02 drain wiring 37.

On the pixel electrode 45, an EL layer (an organic material is preferable) 46, a cathode 47, and a protective electrode 48 are sequentially formed. The EL layer 46 is used in a single layer or a stacked structure, but is often used in a stacked structure. Various laminated structures have been proposed by combining a light emitting layer, an electron transport layer, an electron injection layer, a hole injection layer, a hole transport layer, or the like, but any structure may be used in the present invention.
Of course, the EL layer may be doped with a fluorescent dye or the like. In this specification, a light-emitting element formed using a pixel electrode (anode), an EL layer, and a cathode is referred to as an EL element.

Any known EL material can be used in the present invention. Known materials include
Organic materials are widely known, and it is preferable to use organic materials in consideration of driving voltage. As the organic EL material, for example, materials disclosed in the following US patents or publications can be used.

US Patent No. 4,356,429, US Patent No. 4,539,507, US Patent No. 4,720,432, US Patent No. 4,769,292, US Patent No. 4,885
211, U.S. Pat.No. 4,950,950, U.S. Pat.No. 5,059,861,
US Patent No. 5,047,687, US Patent No. 5,073,446, US Patent No. 5
, 059,862, US Pat. No. 5,061,617, US Pat. No. 5,151,6
29, U.S. Pat. No. 5,294,869, U.S. Pat. No. 5,294,870, JP-A-10-189252, JP-A-8-2441048, and JP-A-8-78159.

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

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 six-membered ring containing substituents such as hydrogen, alkyl or halogen.

An aromatic tertiary amine can be used as the organic material for the hole transport layer, and preferably includes tetraallyldiamine represented by the following general formula.

Here, Are is an arylene group, n is an integer of 1 to 4, Ar, R ₇ , R ₈ , R ₉
Are the selected allyl groups.

In addition, a metal oxinoid compound can be used as the organic material for the EL layer, the electron transport layer, or the electron injection layer. What is necessary is just to use what is represented with the following general formulas as a metal oxinoid compound.

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

Here, R ₂ -R ₇ is as defined above, L ₁ -L ₅ is a carbohydrate group containing 1 to 12 carbon elements, and L ₁ , L ₂ or L ₂ and L ₃ are both benzo rings. Can be formed. Moreover, the following metal oxinoid compounds may be used.

Here, R ₂ -R ₆ can be replaced. As described above, the organic EL material includes a coordination compound having an organic ligand. 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 absolutely necessary to limit to this.

In addition, when an ink jet method is used as a method for forming the EL layer, the EL material is preferably a polymer material. Typical polymer materials include polymer materials such as polyparaphenylene vinylene (PPV) and polyfluorene. To colorize
For example, cyanopolyphenylene vinylene is preferable for the red light emitting material, polyphenylene vinylene is preferable for the green light emitting material, and polyphenylene vinylene and polyalkylphenylene are preferable for the blue light emitting material. Regarding organic EL materials that can be used in the ink jet method, JP-A-10-012 is disclosed.
All the materials described in the publication No. 377 can be cited.

As the cathode 47, magnesium (Mg) and lithium (Li) having a small work function are used.
A material containing cesium (Cs), barium (Ba), potassium (K), beryllium (Be), or calcium (Ca) is used. Preferably MgAg (Mg and Al are replaced by Mg: Ag
= 10: 1 mixed materials) may be used. Besides, MgAgAl electrode, Li
Examples include an Al electrode and a LiFAl electrode. The protective electrode 48 is an electrode provided for protecting the cathode 47 from external moisture or the like, and is formed of aluminum (Al) or silver (
A material containing Ag) is used. The protective electrode 48 also has a heat dissipation effect.

Note that the EL layer 46 and the cathode 47 are desirably formed continuously without being released to the atmosphere. That is,
It is desirable that all layers of the EL layer and the cathode are continuously formed by a multi-chamber (also referred to as cluster tool) type film forming apparatus. This is because, when an organic material is used as the EL layer, it is very sensitive to moisture, so that moisture absorption when released to the atmosphere is avoided. Furthermore, it is better to continuously form not only the EL layer 46 and the cathode 47 but also the protective electrode 48 thereon.

As the film formation method, since the EL layer is very weak against heat, the vacuum evaporation method (in particular, the organic molecular beam evaporation method is effective in forming an ultra-thin film at the molecular order level), the sputtering method, A plasma CVD method, a spin coating method, a screen printing method, or an ion plating method is preferable, but an ink jet method can also be used. There are a bubble jet (registered trademark) method using cavitation (Japanese Patent Laid-Open No. 5-116297, etc.) and a piezo method using a piezo element (Japanese Patent Laid-Open No. 8-290647, etc.). In view of weakness, the piezo method is preferable.

Reference numeral 49 denotes a second passivation film having a thickness of 10 nm to 1 μm (preferably 2).
(00 to 500 nm). The purpose of providing the second passivation film 49 is mainly for the purpose of protecting the EL layer 46 from moisture. However, as with the first passivation film 41, a heat radiation effect may be provided. Accordingly, the same material as the first passivation film 41 can be used as the forming material. However, when an organic material is used for the EL layer 46, it is preferable that an insulating film that easily releases oxygen is not used because it deteriorates due to bonding with oxygen.

Further, since the EL layer is vulnerable to heat as described above, the EL layer is as low as possible (preferably from room temperature to 120 ° C.).
It is desirable to form the film in a temperature range up to ° C. Therefore, plasma CVD method, sputtering method,
A vacuum deposition method, an ion plating method, or a solution coating method (spin coating method) can be said to be a desirable film forming method.

The EL display device of the present invention has a pixel portion including a pixel having the above structure, and TFTs having different structures are arranged in the pixel in accordance with the function. Accordingly, an EL display device in which a switching TFT having a sufficiently low off-current value and a current control TFT resistant to hot carrier injection can be formed in the same pixel, has high reliability, and can display a good image. Can be formed.

The most important point in the pixel structure of FIG. 1 is that a multi-gate TFT is used as the switching TFT, and the arrangement of the LDD region and the like need not be limited to those shown in FIG.

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

An embodiment of the present invention will be described with reference to FIGS. Here, a method for simultaneously manufacturing a TFT of a pixel portion and a driver circuit portion provided around the pixel portion will be described. However, in order to simplify the description, a CMOS circuit, which is a basic circuit, is illustrated with respect to the drive circuit.

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

In addition, it is effective to provide a heat dissipation layer made of the same material as the first passivation film 41 shown in FIG. Since the current control TFT flows a large current, it easily generates heat, and it is effective to provide a heat dissipation layer 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 formation method. Note that the semiconductor film is not limited to an amorphous silicon film, and any semiconductor film including an amorphous structure (including a microcrystalline semiconductor film) may be used. Further, a compound semiconductor film including an amorphous structure such as an amorphous silicon germanium film may be used. The film thickness may be 20 to 100 nm.

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

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

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

It is effective to form the active layer of the switching TFT that needs to reduce the off current from an amorphous silicon film, and to form the active layer of the current control TFT from a crystalline silicon film. Since the amorphous silicon film has low carrier mobility, it is difficult for an electric current to flow and an off current is difficult to flow. That is, the advantages of both an amorphous silicon film that hardly allows current to flow and a crystalline silicon film that easily allows current to flow can be utilized.

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

Then, resist masks 304a and 304b are formed thereon, and n is interposed through the protective film 303.
An impurity element imparting a type (hereinafter referred to as an n-type impurity element) is added. Note that as the n-type impurity element, an element typically belonging to Group 15 of the periodic table, typically phosphorus or arsenic can be used. In this embodiment, phosphorus is added at a concentration of 1 × 10 ¹⁸ atoms / cm ³ using a plasma doping method in which phosphine (PH ₃ ) is plasma-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 by this process, an n-type impurity element is 2 ×
The dose is adjusted so as to be contained at a concentration of 10 ^{16 to} 5 × 10 ¹⁹ atoms / cm ³ (typically 5 × 10 ^{17 to} 5 × 10 ¹⁸ atoms / cm ³ ).

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

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

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

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

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

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

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

Typically, a film made of an element selected from tantalum (Ta), titanium (Ti), molybdenum (Mo), tungsten (W), or chromium (Cr), or a nitride film of the element (
Typically, a tantalum nitride film, a tungsten nitride film, a titanium nitride film), an alloy film in which the above elements are combined (typically, a Mo—W alloy or a Mo—Ta alloy), or a silicide film of the above elements (typically, For example, a tungsten silicide film or a titanium silicide film) or a silicon film having conductivity can be used. Of course, it may be used as a single layer or may be laminated.

In this embodiment, a laminated film including a tantalum nitride (TaN) film having a thickness of 50 nm and a Ta film having a thickness of 350 nm is used. This may be formed by sputtering. Also, X as the sputtering gas
When an inert gas such as e or Ne is added, film peeling 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 overlapped portion later becomes an LDD region overlapping with the gate electrode.

Next, as shown in FIG. 4A, an n-type impurity element (phosphorus in this embodiment) is added in a self-aligning manner using the gate electrodes 312 to 316 as masks. Impurity regions 31 thus formed
7 to 323 include 1/2 to 1/10 of n-type impurity regions 305 and 306 (typically 1/3 to 1/3).
Adjust to add phosphorus at a concentration of 1/4). Specifically, 1 × 10 ^{16 to} 5 × 10
A concentration of 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 324 are formed so as to cover the gate electrodes and the like.
24d is formed, and an n-type impurity element (phosphorus in this embodiment) is added to form impurity regions 325 to 331 containing phosphorus at a high concentration. Here again, ion doping using phosphine (PH ₃ ) is performed, and the concentration of phosphorus in this region is 1 × 10 ²⁰ to 1 × 10 ²¹ atoms / cm ³ (typically 2 × 10 ^{20 to} 5 × 10 ^20). atoms / cm ³ ).

In this step, the source region or drain region of the n-channel TFT is formed. In the switching TFT, the n-type impurity regions 320 to 3 formed in the step of FIG.
Leave part of 22. 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
₂ × 6 ^{20 to} 3 × 10 ²¹ atoms / cm ³ (typically 5 × 10 ₂ ) by ion doping using ₂ H ₆ ).
Boron is added so that the concentration becomes × 10 ²⁰ to 1 × 10 ²¹ atoms / cm ³ ).

Note that phosphorus is already added to the impurity regions 333 and 334 at a concentration of 1 × 10 ^{16 to} 5 × 10 ¹⁸ atoms / cm ³ , but boron added here is added at a concentration of at least three times that of that. Is done. Therefore, the n-type impurity region formed in advance is completely inverted to the P-type and functions as a P-type impurity region.

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

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

Next, when the activation process is completed, a gate wiring 335 having a thickness of 300 nm is formed. As a material of the gate wiring 335, aluminum (Al) or copper (Cu) is a main component (composition is 5).
It occupies 0 to 100%. A metal film may be used. As the arrangement, the gate electrodes 314 and 315 (corresponding to the gate electrodes 19a and 19b in FIG. 2) of the switching TFT are formed so as to be electrically connected as in the gate wiring 211 in FIG. (Fig. 4 (D))

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

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

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

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

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

Next, a first passivation film 344 is formed with a thickness of 50 to 500 nm (typically 200 to 300 nm). In this embodiment, the first passivation film 344 is 300 nm.
A thick silicon nitride oxide film is used. This may be replaced by a silicon nitride film. Of course, it is possible to use the same material as the first passivation film 41 of FIG.

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

Next, as shown in FIG. 5B, a color filter 345 and a phosphor 346 are formed.
These materials may be known ones. Moreover, these may be formed by patterning separately, or may be formed continuously and patterned in a lump. As a formation method, a screen printing method, an inkjet method, a mask vapor deposition method (a method of selectively forming using a mask material), or the like may be used.

Each film thickness is selected in the range of 0.5 to 5 μm (typically 1 to 2 μm). In particular, the optimum thickness of the phosphor 346 varies depending on the material used. That is, if the thickness is too thin, the color conversion efficiency deteriorates. If the thickness is too thick, the level difference increases and the amount of transmitted light decreases. Therefore, an optimum film thickness must be determined in consideration of both characteristics.

In this embodiment, the colorization method for color-converting the light generated from the EL layer is described as an example. However, when adopting a method for individually preparing the EL layers corresponding to RGB, a color filter or a fluorescent light is used. The body can be omitted.

Next, a second interlayer insulating film 347 made of an organic resin is formed. As the organic resin, polyimide, polyamide, acrylic, BCB (benzocyclobutene), or the like can be used.
In particular, since the second interlayer insulating film 347 has a strong meaning of flattening, acrylic having excellent flatness is preferable. In this embodiment, an acrylic film is formed with a film thickness that can sufficiently flatten the steps between the color filter 345 and the phosphor 346. Preferably 1 to 5 μm (more preferably 2 to 4 μm)
).

Next, a contact hole reaching the drain wiring 343 is formed in the second interlayer insulating film 347 and the first passivation film 344, and a pixel electrode 348 is formed. In this embodiment, a compound electrode (ITO) film of indium oxide and tin oxide is formed to a thickness of 110 nm and patterned to form a pixel electrode. This pixel electrode 348 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 348 is electrically connected to the drain region 331 of the current control TFT via the drain wiring 343. This structure has the following advantages.

Since the pixel electrode 348 is in direct contact with an organic material such as an EL layer (light emitting layer) or a charge transport layer, movable ions contained in the EL layer may diffuse in the pixel electrode. That is, the structure of this embodiment does not connect the pixel electrode 348 directly to the drain region 331 which is a part of the active layer.
By relaying the drain wiring 343, it is possible to prevent mobile ions from entering the active layer.

Next, as shown in FIG. 5C, the EL layer 349, the cathode (MgAg electrode) 350, and the protective electrode 351 are continuously formed without being released to the atmosphere. At this time, it is preferable to perform heat treatment on the pixel electrode 348 to completely remove moisture before forming the EL layer 349 and the cathode 350. Note that a known material can be used for the EL layer 349.

Note that as the EL layer 349, the material described in the section (Best Mode for Carrying Out the Invention) can be used. In this embodiment, as shown in FIG. 19, a hole injection layer (Hole injecting
The EL layer is a four-layer structure including a layer, a hole transporting layer, a light emitting layer (Emitting layer), and an electron transporting layer. However, an electron transporting layer may not be provided. In some cases, an electron injection layer is provided. Further, the hole injection layer may be omitted. As described above, various examples of combinations have already been reported, and any of the configurations may be used.

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

As the light-emitting layer, BPPC, perylene, and DCM can be used as the red light-emitting layer. In particular, an Eu complex represented by Eu (DBM) ₃ (Phen) (J. Kido et al.
Detailed on .al, Appl.Phys., vol.35, pp.L394-396,1996. ) Has a sharp emission at a wavelength of 620 nm and high monochromaticity.

As a green light emitting layer, a material in which several mol% of quinacridone or coumarin is added to Alq ₃ (8-hydroxyquinoline alminium) can be typically used. The chemical formula is as follows.

As the blue light-emitting layer, a distyarylene amine derivative obtained by adding amino-substituted DSA to DSA (distyryarylene derivative) can be typically used. In particular, it is preferable to use distyrylbiphenyl (DPVBi), which is a high-performance material. The chemical formula is as follows.

In addition, although a silicon nitride film having a thickness of 300 nm is provided as the second passivation film 352, it may be formed continuously without being released to the atmosphere after the protective electrode 351. Of course, the same material as the second passivation film 49 of FIG. 1 can be used for the second passivation film 352.

In this example, a four-layer structure composed of a hole injection layer, a hole transport layer, a light-emitting layer, and an electron injection layer is used as an EL layer, but various examples of combinations have already been reported. It doesn't matter. In this embodiment, the MgAg electrode is used as the cathode of the EL element, but other known materials may be used.

The protective electrode 351 is provided in order to prevent the MgAg electrode 350 from being deteriorated, and a metal film mainly composed of aluminum is typical. Of course, other materials may be used. In addition, the EL layer 349
Since the MgAg electrode 350 is very sensitive to moisture, it is desirable that the protective electrode 351 is continuously formed without being released to the atmosphere to protect the EL layer from the outside air.

Note that the thickness of the EL layer 349 is 10 to 400 nm (typically 60 to 160 nm), Mg
The thickness of the Ag electrode 350 may be 180 to 300 nm (typically 200 to 250 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 this embodiment can provide extremely high reliability and improve the operating characteristics by arranging TFTs having an optimal structure not only in the pixel portion but also in the drive circuit portion.

First, a TFT having a structure that reduces hot carrier injection so as not to reduce the operating speed as much as possible is used as an n-channel TFT 205 of a CMOS circuit that forms a driving circuit.
Note that the driver circuit here includes a shift register, a buffer, a level shifter, a sampling circuit (also referred to as a transfer gate), and the like. In the case of performing digital driving, a signal conversion circuit such as a D / A converter may be included.

In this embodiment, as shown in FIG. 5C, the active layer of the n-channel type 205 includes a source region 355, a drain region 356, an LDD region 357, and a channel formation region 358.
The LDD region 357 overlaps with the gate electrode 313 with the gate insulating film 311 interposed therebetween.

The reason why the LDD region is formed only on the drain region side is to prevent the operation speed from being lowered. In addition, the n-channel TFT 205 does not need to care about the off-current value, and it is better to focus on the operation speed than that. Therefore, it is desirable that the LDD region 357 is completely overlapped with the gate electrode 313 to reduce the resistance component as much as possible. That is, it is better to eliminate the so-called offset.

In addition, since the p-channel TFT 206 of the CMOS circuit is hardly concerned about deterioration due to hot carrier injection, it is not particularly necessary to provide an LDD region. Of course, n-channel TFT
As in the case of 205, it is possible to provide an LDD region and take measures against hot carriers.

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

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 TF for current control
In the case of the sampling circuit, the channel formation region 904 is as described in the description of T202.
The difference is that the LDD regions 901a and 901b are provided in such a manner as to sandwich them.

In addition, a pixel portion is formed by forming a pixel having a structure as shown in FIG. Since the structure of the switching TFT and the current control TFT formed in the pixel has already been described with reference to FIG. 1, the description thereof is omitted here.

Actually, when completed up to FIG. 5C, packaging with a housing material such as a highly airtight protective film (laminate film, UV curable resin film, etc.) or a ceramic sealing can so as not to be exposed to the outside air ( (Encapsulation) is preferable. At that time, the reliability (life) of the EL layer is improved by making the inside of the housing material an inert atmosphere or disposing a hygroscopic material (for example, barium oxide) inside.

In addition, when the airtightness is improved by processing such as packaging, a connector (flexible printed circuit: FPC) for connecting the terminal routed from the element or circuit formed on the substrate and the external signal terminal is attached. Completed as a product. In this specification, an EL display device that can be shipped is referred to as an EL module.

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 side driver circuit 603, and a source side driver circuit 604 formed on a glass substrate 601. The switching TFT 605 in the pixel portion is an n-channel TFT, and is arranged at the intersection of the gate wiring 606 connected to the gate side driving circuit 603 and the source wiring 607 connected to the source side driving circuit 604. The drain of the switching TFT 605 is electrically 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, and the EL element 610 is electrically connected to the drain of the current control TFT 608. At this time, if the current control TFT 608 is an n-channel TFT, the drain of the EL element 610 is preferably connected to the drain thereof. If the current control TFT 608 is a p-channel TFT, the anode of the EL element 610 is preferably connected to the drain thereof.

The FPC 611 serving as an external input terminal is provided with input wirings (connection wirings) 612 and 613 for transmitting signals to the driving 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 of this embodiment includes a source side driver circuit 701, a gate side driver circuit (A) 707, a gate side driver circuit (
B) 711 and a pixel portion 706 are provided. Note that in this specification, the drive circuit is a generic name 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, and a buffer 7
04. A sampling circuit (transfer gate) 705 is provided. The gate side 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 a similar structure.

Here, the driving voltages of the shift registers 702 and 708 are 5 to 16 V (typically 10 V), and an n-channel TFT used in a CMOS circuit forming the circuit is 205 in FIG.
The structure shown by is suitable.

The level shifters 703 and 709 and the buffers 704 and 710 have a driving voltage of 14 to 1.
Although it is as high as 6 V, a CMOS circuit including the n-channel TFT 205 in FIG. 5C is suitable as in the shift register. In addition, it is effective in improving the reliability of each circuit that the gate wiring has a multi-gate structure such as a double gate structure or a triple gate structure.

The sampling circuit 705 has a drive voltage of 14 to 16 V. However, since the source region and the drain region are inverted and the off-current value needs to be reduced, the n-channel type TF in FIG.
A CMOS circuit including T208 is suitable.

Further, the pixel portion 706 has a driving voltage of 14 to 16 V, and the pixel having the structure shown in FIG.

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

Further, the EL module of this embodiment including the housing material is shown in FIGS.
A description will be given using B). Note that the reference numerals used in FIGS. 6 and 7 are cited as necessary.

A pixel portion 1701, a source side driver circuit 1702, and a gate side driver circuit 1703 are formed over a substrate (including a base film under the TFT) 1700. Various wirings from the respective driving circuits reach the FPC 611 through the input wirings 612 to 614 and are connected to an external device.

At this time, a housing material 1704 is provided so as to surround at least the pixel portion, preferably the driver circuit and the pixel portion. Note that the housing material 1704 has a recess or a sheet shape whose inner dimension is larger than the outer dimension of the EL element, and is fixed to the substrate 1700 by an adhesive 1705 so as to form a sealed space in cooperation with the substrate 1700. Is done. At this time, the EL element is completely enclosed in the sealed space and is completely shielded from the outside air. Note that a plurality of housing materials 1704 may be provided.

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

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

Further, the air gap 1706 between the housing material and the substrate 1700 is inert gas (argon,
It is desirable to fill with helium, nitrogen, or the like. Moreover, it is also possible to use not only gas but inert liquid (liquid fluorinated carbon represented by perfluoroalkane etc.). As for the inert liquid, a material as used in JP-A-8-78159 may be used. Also,
A resin may be filled.

It is also effective to provide a desiccant in the gap 1706. As a desiccant, JP-A-9
Materials such as those described in -148066 can be used. Typically, barium oxide may be used. It is also effective to provide an antioxidant in addition to the desiccant.

As shown in FIG. 17B, a plurality of pixels each having an isolated EL element are provided in the pixel portion, and all of them have a protective electrode 1707 as a common electrode. In this embodiment, the EL layer, the cathode (MgAg electrode) and the protective electrode are preferably formed continuously without being released to the atmosphere. However, the EL layer and the cathode are formed using the same mask material, and only the protective electrode is separated. If the mask material is used, the structure shown in 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 over the driver circuit. Of course, there is no problem even if it is provided on the driver circuit, but it is preferable not to provide it in consideration of the fact that the EL layer contains an alkali metal.

Note that the protective 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 protective electrode 1707.
It is connected to the FPC 611 through a conductive paste material (typically an anisotropic conductive film) 1710.

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

First, the state shown in FIG. 5A is obtained according to the steps of this embodiment. At this time, the end of the substrate (FIG. 17).
In (B), a region indicated by 1708), the first interlayer insulating film 336 and the gate insulating film 311 are removed, and an input wiring 1709 is formed thereon. Of course, it is formed simultaneously with the source wiring and drain wiring of FIG. (FIG. 18 (A))

Next, when the second interlayer insulating film 347 and the first passivation film 344 are etched in FIG. 5B, a region indicated by 1801 is removed and an opening 1802 is formed. (Fig. 18B)

In this state, an EL element formation process (pixel electrode, EL layer, and cathode formation process) is performed in the pixel portion. At this time, in the region shown in FIG. 18, a mask material is used to prevent the EL element from being formed. Then, after forming the cathode 349, the protective electrode 350 is formed using another mask material. As a result, the protective electrode 350 and the input wiring 1709 are electrically connected. Further, a second passivation film 352 is provided to obtain the state of FIG.

Through the above steps, a contact structure in a region indicated by 1708 in FIG. The input wiring 1709 is filled with a gap between the housing material 1704 and the substrate 1700 (however, it is filled with an adhesive 1705. That is, the adhesive 1705 needs to have a thickness that can sufficiently flatten the steps of the input wiring. .) Is connected to the FPC 611. Although the input wiring 1709 has been described here, the other input wirings 612 to 614 are similarly connected to the FPC 611 under the housing material 1704.

In this embodiment, an example in which the pixel configuration is different from the configuration shown in FIG. 2B is shown in FIG.

In this embodiment, the two pixels shown in FIG. 2B are arranged so as to be symmetric 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 necessary wirings can be reduced. Note that the TFT structure and the like disposed in the pixel can be left as they are.

With such a configuration, a higher-definition pixel portion can be manufactured, and the image quality is improved.

Note that the structure of this embodiment can be easily realized in accordance with the manufacturing process of Embodiment 1, and the description of Embodiment 1 and FIG.

In this embodiment, the case where a pixel portion having a structure different from that in FIG. 1 is formed will be described with reference to FIGS. The first embodiment may be followed up to the step of forming the second interlayer insulating film 44. Further, the switching TFT 201 and the current control TFT 202 covered with the second interlayer insulating film 44 have the same structure as that shown in FIG.

In the case of the present embodiment, when contact holes are formed in the second interlayer insulating film 44 and the first passivation film 41, the pixel electrode 51, the cathode 52, and the EL layer 53 are formed. In this embodiment, the cathode 52 and the EL layer 53 are continuously formed by a vacuum deposition method that does not release to the atmosphere. At that time, a red light emitting EL layer, a green light emitting EL layer, and a blue light emitting are selectively used using a mask material. The EL layer is formed on 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. A known material may be used for the EL layers of these colors.

In this embodiment, an aluminum alloy film (aluminum film containing 1 wt% titanium) having a thickness of 150 nm is provided as the pixel electrode 51. The material for the pixel electrode may be any material as long as it is a metal material, but is preferably a material having high reflectivity. Further, a 230 nm-thick MgAg electrode is used as the cathode 52, and the EL layer 53 has a thickness of 90 nm (from the bottom, the electron transport layer 20 nm, the light emitting layer 40 nm, and the hole transport layer 30 nm).

Next, an anode 54 made of a transparent conductive film (ITO film in this embodiment) is formed to a thickness of 110 nm. Thus, the EL element 209 is formed, and the pixel having the structure shown in FIG. 11 is completed by forming the second passivation film 55 with the material shown in the first embodiment.

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

The configuration of this embodiment can be freely combined with any of the configurations of Embodiments 1 and 2.

In this embodiment, a pixel having a structure different from that in FIG.
A description will be given with reference to A) and (B).

In FIG. 12A, reference numeral 1201 denotes a switching TFT, which includes an active layer 56, a gate electrode 57a, a gate wiring 57b, a source wiring 58, and a drain wiring 59 as a configuration.
Reference numeral 1202 denotes a current control TFT, which is an active layer 60, a gate electrode 61, and a source wiring 6.
2 and drain wiring 63 as a configuration. The source wiring 62 of the current control TFT 1202 is connected to the current supply line 64, and the drain wiring 63 is connected to the EL element 65.
FIG. 12B shows the circuit configuration of this pixel.

The difference between FIG. 12A and FIG. 2A is the structure of the switching TFT. In this embodiment, a thin gate electrode 57a having a line width of 0.1 to 5 μm is formed, and an active layer 56 is formed so as to cross that 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 occupying much area.

The other portions are the same as in FIG. 2A, but with the structure as in this embodiment, the area occupied by the switching TFT is reduced, so the effective light emission area is increased, that is, the brightness of the image is improved. . In addition, since the gate structure with increased redundancy for reducing the off-current value can be realized, the image quality can be further improved.

Note that the configuration of this embodiment may be configured such that the current supply line 64 is shared between adjacent pixels as in the second embodiment, or may be configured as in the third embodiment. In addition, the manufacturing process may be according to Example 1.

In the first to fourth embodiments, the case of a top gate TFT has been described. However, the present invention may be implemented using a bottom gate TFT. In this embodiment, FIG. 13 shows the case where the present invention is implemented using an inverted staggered TFT. Since the structure other than the TFT structure is the same as that in FIG. 1, the same reference numerals as those in FIG. 1 are used as necessary.

In FIG. 13, the same material as in the first embodiment can be used for the substrate 11 and the base film 12. A switching TFT 1301 and a current control TFT 13 are formed on the base film 12.
02 is formed.

The configuration of the switching TFT 1301 includes gate electrodes 70a and 70b, a gate wiring 71,
Gate insulating film 72, source region 73, drain region 74, LDD regions 75a to 75d, high concentration impurity region 76, channel forming regions 77a and 77b, channel protective films 78a and 78b, first
An interlayer insulating film 79, a source wiring 80, and a drain wiring 81 are included.

The current control TFT 1302 includes a gate electrode 82, a gate insulating film 72, a source region 83, a drain region 84, an LDD region 85, a channel forming region 86, a channel protective film 87, a first interlayer insulating film 79, and a source wiring. 88 and drain wiring 89. At this time, the gate electrode 82 is electrically connected to the drain wiring 81 of the switching TFT 1301.

Note that the switching TFT 1301 and the current control TFT 1302 may be formed by a known method for manufacturing an inverted staggered TFT. In addition, each part for forming the TFT (
As the material of the wiring, the insulating film, the active layer, etc., the same material as that of each corresponding part in the top gate type TFT of Embodiment 1 can be used. However, the channel protective films 78a, 78b, and 87 that are not included in the top gate TFT may be formed of an insulating film containing silicon. In addition, the impurity regions such as the source region, the drain region, and the LDD region may be formed by individually changing the impurity concentration using a photolithography technique.

When the TFT is completed, the first passivation film 41, the insulating film (flattening film) 44, the pixel electrode (anode) 45, the EL layer 46, the MgAg electrode (cathode) 47, the aluminum electrode (protective electrode) 48, the second passivation film. 49 are sequentially formed to complete a pixel having the EL element 1303. Example 1 may be referred to for these manufacturing steps and materials.

In addition, the structure of a present Example can be freely combined with any structure of Examples 2-4.

In the structure of FIG. 5C or FIG. 1 of the first embodiment, a material having a high heat dissipation effect is used as a base film provided between the active layer and the substrate, like the first passivation film 41 and the second passivation film 49. It is effective to use. In particular, the current control TFT easily generates heat because a large amount of current flows, and deterioration due to self-heating can be a problem. In such a case, the thermal degradation of the TFT can be prevented because the base film has a heat dissipation effect as in this embodiment.

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

In addition, the structure of a present Example can be freely combined with any structure of Examples 1-5.

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

Therefore, 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 and the first passivation film 41. That is, since it is not necessary to worry about a decrease in transmittance, the film thickness can be set as thick as 100 to 500 nm, and the heat dissipation effect can be further enhanced.

Note that when the carbon film is used for the second passivation film 49, a decrease in transmittance should be avoided, so the film thickness is preferably about 5 to 100 nm.

In this embodiment, even when a carbon film is used for the base film 12, the first passivation film 41, or the second passivation film 49, it is effective to use it by laminating with another insulating film.

Note that this embodiment is effective when the pixel structure shown in Embodiment 3 is used, and other configurations can be freely combined with any of the configurations of Embodiments 1 to 6.

The present invention is characterized in that the switching TFT has a multi-gate structure in the pixel of the EL display device, thereby reducing the off-current value of the switching TFT and eliminating the necessity of the storage capacitor. 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 widening the effective light emitting area can be obtained only by reducing the exclusive area. That is, the object of the present invention can be sufficiently achieved by merely reducing the off-current value and reducing the area occupied by the storage capacitor by providing the switching TFT with a multi-gate structure.

Therefore, a pixel structure as shown in FIG. 14 is also possible. In FIG. 14, the same reference numerals as those in FIG.

The difference between FIG. 14 and FIG. 1 is that there is a storage capacitor 1401 connected to the switching TFT. The storage capacitor 1401 is formed of a semiconductor region (lower electrode) 1402 extended from the drain region 14 of the switching TFT 201, a gate insulating film 18, and a capacitor electrode (upper electrode) 1403. The capacitor electrode 1403 is a TFT gate electrode 19a, 19b,
35 and at the same time.

This top view is shown in FIG. A cross-sectional view taken along line AA ′ in FIG. 15A corresponds to FIG. As shown in FIG. 15A, the capacitor electrode 1403 is electrically connected to the source region 31 of the current control TFT through an 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. 15B illustrates a circuit configuration of the top view illustrated in FIG.

In addition, the structure of a present Example can be freely combined with any structure of Examples 1-7. That is, only a storage capacitor is provided in the pixel, and the TFT structure and the material of the EL layer are not limited.

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

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

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

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

As described above, the manufacturing process shown in Embodiment 1 is an example, and other manufacturing processes can be used as long as the structure of FIG. 1 or FIG. 5C of Embodiment 1 can be realized. No problem.

In addition, the structure of a present Example can be freely combined with any structure of Examples 1-8.

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

When analog driving is performed, 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 control TFT. Then, the current control TFT controls the current flowing in the EL element, and the light emission intensity of the EL element is controlled to perform gradation display. In this case, it is desirable to operate the current control TFT in a saturation region. That is, it is desirable to operate within the condition of | Vds |> | Vgs−Vth |. Here, Vds
Is a voltage between the source region and the drain region, Vgs is a voltage between the source region and the gate electrode, and Vth is a threshold voltage of the TFT.

On the other hand, when digital driving is performed, unlike analog gray scale display, gray scale display called time-division driving (time gray scale driving) or area gray scale driving is performed. That is, the color gradation is visually changed by adjusting the length of the light emission time and the light emission area ratio. in this case,
The current control TFT is desirably operated in a linear region. That is, | Vds | <| Vgs−V
It is desirable to operate within the condition of th |.

Since an EL element has a very high response speed compared to a liquid crystal element, it can be driven at a high speed. Therefore, it can be said that the element is suitable for time-division driving in which gradation display is performed by dividing one frame into a plurality of subframes. Further, since one frame period is short, the time for holding the gate voltage of the current control TFT can be shortened, which is advantageous in reducing or omitting the holding capacitor.

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

In this embodiment, an example of a pixel structure of an EL display device of the present invention is shown in FIGS.
In this embodiment, 4701 is the source wiring of the switching TFT 4702, 47
03 is the gate wiring of the switching TFT 4702, 4704 is the current control TFT, 47
05 is a current supply line, 4706 is a power supply control TFT, 4707 is a power supply control gate wiring, 4
Reference numeral 708 denotes an EL element. Regarding the operation of the power supply control TFT 4706, refer to Japanese Patent Application No. 11-34.
Refer to No. 1272.

In this embodiment, the power control TFT 4706 is provided between the current control TFT 4704 and the EL element 4708. However, the current control TFT 4704 is provided between the power control TFT 4706 and the EL element 4708. Also good. Also, the power control TFT 47
It is preferable that 06 has the same structure as the current control TFT 4704 or is formed in series with the same active layer.

FIG. 21A shows an example in which the current supply line 4705 is shared between two pixels. That is, there is a feature in that the two pixels are formed so as to be symmetrical with respect to the current supply line 4705. In this case, since the number of current supply lines can be reduced, the pixel portion can be further refined.

FIG. 21B shows an example in which a current supply line 4710 is provided in parallel with the gate wiring 4703 and a power supply control gate wiring 4711 is provided in parallel with the source wiring 4701. In addition,
In FIG. 21B, the current supply line 4710 and the gate wiring 4703 are provided so as not to overlap with each other. However, if the wirings are formed in different layers, the current supply line 4710 and the gate wiring 4703 are overlapped with an insulating film interposed therebetween. It can also be provided. In this case, the current supply line 4710 and the gate wiring 4703 can share an exclusive area, so that the pixel portion can be further refined.

In this embodiment, an example of a pixel structure of an EL display device of the present invention is shown in FIGS.
In this embodiment, reference numeral 4801 denotes a source wiring of the switching TFT 4802,
03 is a gate wiring of the switching TFT 4802, 4804 is a current control TFT, 48
Reference numeral 05 denotes a current supply line, 4806 denotes an erasing TFT, 4807 denotes an erasing gate wiring, and 4808 denotes an EL element. Refer to Japanese Patent Application No. 11-338786 for the operation of the erasing TFT 4806.

The drain of the erasing TFT 4806 is connected to the gate of the current control TFT 4804 so that the gate voltage of the current control TFT 4804 can be forcibly changed. Note that the erasing TFT 4806 may be either 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. 22A illustrates an example in which the current supply line 4805 is shared between two pixels. In other words, the two pixels are formed so as to be symmetrical about the current supply line 4805. In this case, since the number of current supply lines can be reduced, the pixel portion can be further refined.

FIG. 22B shows an example in which a current supply line 4810 is provided in parallel with the gate wiring 4803 and an erasing gate wiring 4811 is provided in parallel with the source wiring 4801. Note that FIG.
In FIG. 2B, the current supply line 4810 and the gate wiring 4803 are provided so as not to overlap each other. However, if the wirings are formed in different layers, the current supply line 4810 and the gate wiring 4803 are provided so as to overlap each other with an insulating film interposed therebetween. You can also. In this case, the current supply line 4810 and the gate wiring 4803 can share an exclusive area, so that the pixel portion can be further refined.

The EL display device of the present invention may have a structure in which any number of TFTs are provided in a pixel. Example 1
1 and 12 show an example in which three TFTs are provided, but four to six TFTs may be provided. The present invention can be practiced without being limited to the pixel structure of an EL display device.

In this embodiment, an example in which a p-channel TFT is used as the current control TFT 202 in FIG. 1 will be described. Since other parts are the same as those in FIG. 1, detailed description thereof is omitted.

FIG. 23 shows a cross-sectional structure of the pixel of this example. For the manufacturing method of the p-channel TFT used in this embodiment, Embodiment 1 may be referred to. The active layer of the p-channel TFT is a source region 91,
The drain region 92 and the channel formation region 93 are included.
In addition, the drain region 92 is connected to the drain wiring 37.

Thus, when the anode of the EL element is connected to the current control TFT, the current control TF
It is preferable to use a p-channel TFT as T.

In addition, the structure of a present Example can be implemented in combination with any structure of Examples 1-13 freely.

In the present invention, by using an EL material that can use phosphorescence from triplet excitons for light emission, the external light emission quantum efficiency can be dramatically improved. This makes it possible to reduce the power consumption, extend the life, and reduce the weight of the EL element. Here, a report of using triplet excitons to improve the external emission quantum efficiency is shown. (T.Tsutsui, C.Adachi, S.Saito, Photochemical
Processes in Organized Molecular Systems, ed.K.Honda, (Elsevier Sci.Pub., Tokyo
, 1991) p.437.) The molecular formula of the EL material (coumarin dye) reported in the above paper is shown below.

(MABaldo, DFO'Brien, Y.You, A.Shoustikov, S.Sibley, METhompson, S.
R. Forrest, Nature 395 (1998) p.151.)
The molecular formula of the EL material (Pt complex) reported in the above paper is shown below.

(MABaldo, S.Lamansky, PEBurrrows, METhompson, SRForrest, Appl.Ph
ys.Lett., 75 (1999) p.4.) (T.Tsutsui, M.-J.Yang, M.Yahiro, K.Nakamura, T.Watanabe,
T.tsuji, Y.Fukuda, T.Wakimoto, S.Mayaguchi, Jpn.Appl.Phys., 38 (12B) (1999) L15
02.)
The molecular formula of the EL material (Ir complex) reported in the above paper is shown below.

As described above, if phosphorescence emission from triplet excitons can be used, in principle, it is possible to realize an external emission quantum efficiency that is 3 to 4 times higher than that in the case of using fluorescence emission from singlet excitons. In addition, the structure of a present Example can be implemented in combination freely with any structure of Examples 1-13.

In Example 1, it was preferable to use an organic EL material as the EL layer, but the present invention can also be implemented using an inorganic EL material. However, since current inorganic EL materials have a very high driving voltage, when performing analog driving, a TF having a withstand voltage characteristic that can withstand such driving voltage.
T must be used.

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

Moreover, the structure of a present Example can be freely combined with any structure of Examples 1-14.

Active matrix EL display device (EL module) formed by implementing the present invention
Is self-luminous and has excellent visibility in a bright place as compared with a liquid crystal display device. Therefore, a direct-view type EL display (refers to a display that incorporates an EL module)
As a wide use.

One of the advantages of the EL display over the liquid crystal display is the wide viewing angle. Therefore, in order to watch TV broadcasts or the like on a large screen, the EL display of the present invention may be used as a display display (display monitor) having a diagonal of 30 inches or more (typically 40 inches or more).

Further, it 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 display of various electronic devices.

Such electronic devices include video cameras, digital cameras, goggle-type displays (head-mounted displays), car navigation systems, personal computers, personal digital assistants (such as mobile computers, mobile phones or electronic books), and images with recording media. A playback device (specifically, a device provided with a display capable of playing back a recording medium such as a compact disc (CD), a laser disc (LD), or a digital video disc (DVD) and displaying an image thereof). Examples of these electronic devices are shown in FIG.

FIG. 16A illustrates 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, and an audio input portion 21.
03, an operation switch 2104, a battery 2105, and an image receiving unit 2106. The present invention can be used for the display portion 2102.

FIG. 16C illustrates a goggle type display including a main body 2201, a display portion 2202, and an arm portion 2203. The present invention can be used for the display portion 2202.

FIG. 16D illustrates a portable (mobile) computer, which includes a main body 2301, a camera unit 23.
02, an image receiving unit 2303, an operation switch 2304, and a display unit 2305. The present invention can be used for the display portion 2305.

FIG. 16E shows an image reproducing device (specifically, a DVD reproducing device) provided with a recording medium.
Main body 2401, recording medium (CD, LD, DVD, etc.) 2402, operation switch 2403
Display unit (a) 2404 and display unit (b) 2405. The display unit (a) mainly displays image information, and the display unit (b) mainly displays character information.
), (B). In addition, as an image reproducing apparatus provided with a recording medium, a CD
The present invention can be used in a playback device, a game machine, and the like.

FIG. 16F illustrates an EL display, which includes a housing 2501, a support base 2502, and a display portion 25.
03 is 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 displays 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 electronic devices often display information distributed through electronic communication lines such as the Internet and CATV (cable television), and in particular, opportunities for displaying moving image information are increasing. Since the response speed of the EL material is very high, it is suitable for performing such moving image display.

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

Here, FIG. 20A shows a mobile phone, which includes a main body 2601, an audio output portion 2602, an audio input portion 2603, a display portion 2604, operation switches 2605, and an antenna 2606. The EL display device of the present invention can be used for the display portion 2604. Note that the display portion 2604 can suppress power consumption of the mobile phone by displaying white characters on a black background.

FIG. 20B illustrates in-vehicle audio (car audio), which includes a main body 2701, a display portion 2702, and operation switches 2703 and 2704. The EL display device of the present invention can be used for the display portion 2702. In this embodiment, in-vehicle audio is shown, but it may be used for stationary audio. Note that the display portion 2702 can reduce 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 various fields. Further, the electronic device of the present embodiment can be realized by using a configuration including any combination of Embodiments 1 to 16.

FIG. 11 illustrates a cross-sectional structure of a pixel portion of an EL display device. FIG. 11 illustrates a top structure and a structure of a pixel portion of an EL display device. 10A and 10B illustrate a manufacturing process of an active matrix EL display device. 10A and 10B illustrate a manufacturing process of an active matrix EL display device. 10A and 10B illustrate a manufacturing process of an active matrix EL display device. The figure which shows the external appearance of EL module. FIG. 11 is a diagram illustrating a circuit block configuration of an EL display device. The figure which expanded the pixel part of EL display apparatus. FIG. 11 shows an element structure of a sampling circuit of an EL display device. FIG. 11 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. 11 illustrates a top structure and 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. 11 illustrates a cross-sectional structure of a pixel portion of an EL display device. FIG. 11 illustrates a top structure and a structure of a pixel portion of an EL display device. FIG. 11 is a diagram illustrating a specific example of an electronic device. The figure which shows the external appearance of EL module. The figure which shows the preparation process of contact structure. The figure which shows the laminated structure of EL layer. FIG. 11 is a diagram illustrating a specific example of an electronic device. FIG. 11 illustrates a circuit configuration of a pixel portion of an EL display device. FIG. 11 illustrates a circuit configuration 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.

Claims (21)

A substrate,
Transistors on the substrate, wiring,
A source wiring and a drain wiring electrically connected to the transistor on the transistor;
An interlayer insulating film on the source wiring and drain wiring;
A light emitting element having a first electrode electrically connected to the source wiring or the drain wiring on the interlayer insulating film, a light emitting layer on the first electrode, and a second electrode on the light emitting layer When,
A housing material having a concave shape on the light emitting element,
The housing material is bonded to the substrate via an adhesive,
The wiring has first to third regions,
The first region is provided inside the housing material, and is electrically connected to the second electrode;
The second region overlaps the adhesive and the housing material, and is provided between the adhesive and the substrate;
The third region is provided outside the housing material;
The display device, wherein the wiring is a conductive film formed simultaneously with the source wiring and the drain wiring. A substrate,
Transistors on the substrate, wiring,
A first interlayer insulating film on the transistor;
A source wiring and a drain wiring electrically connected to the transistor on the first interlayer insulating film;
A second interlayer insulating film on the source wiring and drain wiring;
A first electrode electrically connected to the source wiring or the drain wiring on the second interlayer insulating film, a light emitting layer on the first electrode, and a second electrode on the light emitting layer; A light emitting device having
A housing material having a concave shape on the light emitting element,
The housing material is bonded to the substrate via an adhesive,
The wiring is provided to partially extend on the first interlayer insulating film,
The wiring has first to third regions,
The first region is provided on the inner side of the housing material and electrically connected to the second electrode on the first interlayer insulating film through an opening provided in the second interlayer insulating film. Connected,
The second region overlaps the adhesive and the housing material, and is provided between the adhesive and the substrate;
The third region is provided outside the housing material;
The display device, wherein the wiring is a conductive film formed simultaneously with the source wiring and the drain wiring. A substrate,
Transistors on the substrate, wiring,
A first interlayer insulating film on the transistor;
A source wiring and a drain wiring electrically connected to the transistor on the first interlayer insulating film;
A passivation film on the source wiring and drain wiring;
A second interlayer insulating film on the passivation film;
A first electrode electrically connected to the source wiring or the drain wiring on the second interlayer insulating film; a light emitting layer on the first electrode; and a second electrode on the light emitting layer. A light emitting device having
A housing material having a concave shape on the light emitting element,
The housing material is bonded to the substrate via an adhesive,
The wiring is provided to partially extend on the first interlayer insulating film,
The wiring has first to third regions,
The first region is provided inside the housing material, and the second region is formed on the first interlayer insulating film through an opening provided in the second interlayer insulating film and the passivation film. Is electrically connected to the electrode of
The second region overlaps the adhesive and the housing material, and is provided between the adhesive and the substrate;
The third region is provided outside the housing material;
The display device, wherein the wiring is a conductive film formed simultaneously with the source wiring and the drain wiring.   4. The display device according to claim 3, further comprising a color filter and a phosphor on the color filter between the passivation film and the second interlayer insulating film.   5. The display device according to claim 3, wherein the passivation film is an insulating film containing silicon.   5. The display device according to claim 3, wherein the passivation film is a silicon nitride film or a silicon nitride oxide film.   7. The display device according to claim 2, wherein the first interlayer insulating film is an insulating film containing silicon.   8. The display device according to claim 2, wherein the second interlayer insulating film is a resin film.   9. The display device according to claim 2, wherein an insulating film is provided over the second interlayer insulating film.   2. The display device according to claim 1, wherein the interlayer insulating film is a resin film.   The display device according to claim 1, wherein the housing material is glass.   The display device according to claim 1, wherein a drying agent is provided in the concave portion.   The display device according to claim 1, wherein the first electrode is made of a transparent conductive film.   14. The display device according to claim 1, wherein the second electrode is a stacked layer of a cathode and a protective electrode.   15. The display device according to claim 1, wherein an active layer of the transistor is a single crystal semiconductor film.   15. The display device according to claim 1, wherein the active layer of the transistor is a polycrystalline semiconductor film.   15. The display device according to claim 1, wherein an active layer of the transistor is a microcrystalline semiconductor film.   The display device according to claim 1, wherein titanium is used for the source wiring and the drain wiring.   The display device according to claim 1, wherein aluminum is used for the source wiring and the drain wiring.   The display device according to claim 1, wherein the display device is used in a display unit of a video camera, a digital camera, a goggle type display, a car navigation system, a personal computer, or a portable information terminal.   20. The display device according to claim 1, wherein the display device is used for a car audio display unit.

Images