JP2002083689A - Luminescence device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a means which makes light extraction efficiency of a luminescence device enhanced, using an EL material. SOLUTION: In the luminescence device, which is prepared with a light- shading section 105 in contact with a transparent electrode 101 which a pixel has, a light (visible light) which the light generated in the EL layer 102 leeks from the end section of the transparent electrode 101, can be intercepted or reflected by preparing the light shading section 105 in the end of the transparent electrode 101. As a result this, loss of the light produced in the EL layer 102 and light leakage to next pixels can be prevented, and it becomes possible to significantly enhance the extraction efficiency of light.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a luminescent material (hereinafter referred to as E) which is capable of emitting fluorescence or phosphorescence by applying an electric field between an opaque electrode (cathode) and a transparent electrode (anode).
The present invention relates to a light-emitting device formed by forming an EL (electroluminescence) element sandwiching an L material on a substrate. Specifically, the present invention relates to improvement of light extraction efficiency from an EL element.

[0002] In the present invention, a light emitting device refers to an image display device or a light emitting device using an EL element. Also, a connector such as an anisotropic conductive film (FPC: Flexible Printed Circuit) or T
AB (Tape Automated Bonding) tape or TCP (T
ape Carrier Package) mounted module,
A module with a printed wiring board at the end of a TAB tape or TCP, or a COG (Chip On Glas
s) All the modules in which an IC (integrated circuit) is directly mounted by the method are included in the light emitting device.

[0003]

2. Description of the Related Art In recent years, the technology for forming a TFT on a substrate has been greatly advanced, and its application to an active matrix type display device (light emitting device) has been developed. In particular, a TFT using a polysilicon film has 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. Therefore, the control of the pixel, which has been conventionally performed by the drive circuit outside the substrate, can be performed by the drive circuit formed on the same substrate as the pixel.

[0004] Such active matrix light-emitting devices can be manufactured by forming various circuits and elements on the same substrate to reduce the manufacturing cost, downsize the electro-optical device, increase the yield, and improve the throughput. Advantages are obtained.

Further, active matrix type light-emitting devices (EL displays) having EL elements as self-luminous elements have been actively studied.

In this specification, in an EL display which is an example of a light emitting device, an EL element has a structure in which an EL layer is sandwiched between a pair of electrodes (anode and cathode). , And has a laminated structure. A typical example is a laminated structure of “hole transport layer / light emitting layer / electron transport layer” proposed by Tang et al. Of Kodak Eastman Company. This structure has extremely high luminous efficiency,
At present, almost all EL displays that are being researched and developed adopt this structure.

In addition, a hole injection layer / hole transport layer / light-emitting layer / electron transport layer, or a hole injection layer / hole transport layer / light-emitting layer / electron transport layer / electron injection layer may be provided on the anode. A structure in which layers are sequentially stacked may be used. The light emitting layer may be doped with a fluorescent dye or the like.

In this specification, all layers provided between a cathode and an anode are collectively called an EL layer. Therefore, the above-described hole injection layer, hole transport layer, light-emitting layer, electron transport layer, electron injection layer, and the like are all included in the EL layer.

Then, a predetermined voltage is applied to the EL layer having the above-mentioned structure from a pair of electrodes, whereby recombination of carriers occurs in the light emitting layer to emit light. In this specification, a light emitting element formed by an anode, an EL layer, and a cathode is referred to as E.
It is called an L element.

The EL layer of the EL element has heat, light, moisture,
Since deterioration is promoted by oxygen or the like, generally, in manufacturing an active matrix type EL display, an EL element is formed after forming a wiring or a TFT in a pixel portion.

After the EL element is formed, the substrate (EL panel) on which the EL element is provided and the cover material are separated by EL.
The elements are bonded so as not to be exposed to the outside air and sealed (packaged) with a sealing material or the like.

After airtightness is improved by processing such as packaging, a connector (FPC, TAB, etc.) for connecting a terminal routed from an element or a circuit formed on the substrate to an external signal terminal is attached. Thus, an active matrix type EL display is completed.

[0013]

In recent years, EL display devices having EL elements have been developed. This is a current-driven self-luminous element utilizing light emission generated by recombination of electrons and holes injected from the electrodes on both sides into the EL layer by application of a voltage, and the light emission is extracted as planar light emission. . However, when the light generated in the EL layer is extracted outside the EL element as planar light emission, the light extraction efficiency is extremely low, usually 20% or less.

Light generated in the EL layer is guided inside the transparent electrode depending on the incident angle of the light. The light guided in this way is called guided light, and this guided light is partially absorbed and disappears, and the rest propagates through the solid thin film forming the transparent electrode and escapes to the end face, so that the light is transmitted to the pixel. Can only be extracted as planar light emission, and in some cases, light leaks to adjacent pixels.

[0015]

Therefore, in the present invention, E
By forming a structure in which the light generated in the L layer does not escape from the end face of the transparent electrode, the light extraction efficiency is improved, and the problem that the image is blurred due to light leakage to the adjacent pixels is solved. The purpose is to do.

FIG. 1 shows the configuration of the present invention. Note that in the light emitting device of the present invention, a plurality of pixels are formed in a matrix in a pixel portion, and each pixel includes a transparent electrode 101 and an EL layer 10.
A light emitting element 104 comprising an opaque electrode 103, and a thin film transistor (T) for driving the light emitting element.
FT) (not shown) via wiring. Note that the wiring here means a conductive material for forming an electrical connection.

The transparent electrode 1 formed on the insulating surface 100
When carriers are injected into the EL layer 102 from the opaque electrode 103 and the opaque electrode 103, light is obtained by recombination of the carriers in the EL layer 102. The transparent electrode 1
01 denotes an electrode provided on the side from which light is emitted because light (visible light) generated in the EL layer 102 can be transmitted therethrough, and transmits light opposite to the opaque electrode 103. An electrode provided on the side where light is not emitted because it cannot be performed.

Therefore, a light-shielding portion is provided between the transparent electrodes of adjacent pixels so that light generated in the EL layer 102 in the pixel 1 does not leak to the pixels 2 or 3 adjacent to the pixel 1. The light-shielding portion formed at this time may be formed in contact with the end of the transparent electrode, but does not necessarily have to be in contact.

The light-shielding portion 105 in the present invention is:
Light that is formed on the insulating surface 100 on which the transparent electrode 101 is formed and emitted by the EL layer 102 of the EL element 104 is guided through the inside of the transparent electrode 101 to block light from leaking from its end or Refers to a part that has a reflecting function. Note that the end portion of the transparent electrode 101 may be formed so as to be in contact with the light-shielding portion 105 or may be formed so as not to be in contact therewith.

The light-shielding portion 105 referred to in this specification is made of a light-shielding material that blocks light, and these materials may be a conductive material or an insulating material. Note that the conductive material referred to here refers to a material having electric conductivity, and a material having sufficiently small electric conductivity and classified as an insulator is distinguished as an insulating material.

When a conductive material is used for the light-shielding portion 105, a wiring connecting the TFT and the transparent electrode can function as the light-shielding portion 105.

As the conductive material used for the light shielding portion 105, it is preferable to use a material having a high reflectance. In addition,
The reflectance in this specification refers to the ratio of the energy of reflected light to the energy of light (incident light) incident on the surface of a material in the visible light region. Has a reflectance of at least 60% or more, preferably 80% or more. Specifically, Ag, Al, Ta, Nb, Mo, Cu, M
It refers to materials such as g, Ni, and Pb.

On the other hand, the light shielding portion 105 is formed by using an insulating material.
In the case where is formed, a material such as polyimide, polyamide, acrylic, or BCB (benzocyclobutene) in which black pigment or carbon is dispersed can be used.

In this specification, the EL element 10
4 is an opaque electrode 103 made of an opaque electrode material;
An element having a structure including a transparent electrode 101 made of a transparent electrode material and an EL layer 102 interposed therebetween. As the structure of the EL layer, the EL layer may be composed of only the light emitting layer that provides a recombination field, or may be an electron injection layer, an electron transport layer, a hole transport layer, an electron blocking layer, and a hole blocking layer, if necessary. An EL layer including a layer or a hole injection layer may be used. That is, in this specification, an EL layer includes all layers in which carriers are injected, transported, or recombined from an electrode.

By providing the light-shielding portion, light that is going to enter from the transparent electrode toward the light-shielding portion is blocked and reflected or absorbed. This controls the direction of the light.

As described above, according to the present invention, the EL element 104
The light generated in the EL layer 102 is formed by forming the light shielding portion 105 at the end of the transparent electrode 101 forming the transparent electrode 10.
Light loss due to escape from the end of the light-emitting device 1 and light leakage to an adjacent pixel can be prevented, and light extraction efficiency can be greatly increased.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG. Although FIG. 1 considers the case of having the structure shown in FIG. 2, it is simplified for convenience of explanation.

In FIG. 1, reference numeral 101 denotes a transparent electrode made of a transparent metal material, and has a function as an anode. In addition, indium tin oxide (IT
O) 2-20% zinc oxide (Z
It is preferable to use a transparent conductive film mixed with nO). Gallium (Ga) to further increase the transmittance and conductivity of visible light
An oxide conductive film such as zinc oxide (ZnO: Ga) to which is added is preferably used.

Reference numeral 102 denotes an EL layer, and reference numeral 103 denotes an opaque electrode, which has a function as a cathode. And
An element including the opaque electrode 103, the EL layer 102, and the transparent electrode 101 is referred to as an EL element in this specification.

Light is generated by recombination of electrons injected from the cathode and holes injected from the anode in the EL layer of the EL element. Note that in this embodiment mode, light emitted from the EL layer is transmitted through the transparent electrode 101 to cause a pixel to emit light.

However, when a part of the light is guided inside the transparent electrode when transmitting through the transparent electrode 101, that is, when guided light is generated, the light is confined inside the transparent electrode and the light is transmitted from the end of the transparent electrode. Leakage occurs.

As a result, when the luminance of the pixel portion is reduced due to the loss of light, or when a part of the light is incident on an adjacent pixel due to light leakage, the contrast of the pixel is reduced and the pixel is blurred.

Therefore, by providing a light shielding portion 105 having a function of blocking light at an end of the transparent electrode 101, light loss and light leakage are prevented.

As the light-shielding portion 105, a material that reflects light leaking from the end of the transparent electrode 101 may be used, or a material that simply blocks light so as not to leak light may be used.

It is preferable to use a material having a high reflectivity as a material used for the light shielding portion 105. Note that a material having a high reflectance in the present specification preferably has a light reflectance of 60% or more in a visible light region, and more preferably 80% or more. Specifically, Ag, Al, Ta, Nb, Mo, Cu, Mg, N
It refers to materials such as i and Pb.

Further, the light-shielding portion 105 may have different shapes depending on the structure for forming the EL element. This will be described later in detail in an embodiment.

As described above, by providing the light shielding portion 105 so as to be in the same layer as the transparent electrode 101, for example, as shown in FIG.
Even if the light enters the pixel 2 or the pixel 3 from the end of the pixel 1, the light can be reflected and blocked.

Next, FIG. 2 shows a cross-sectional structure near a pixel provided with a light-shielding portion. First, a thin film transistor (T
An FT (thin film transistor) is formed. FIG. 2 shows a current control TFT 206 electrically connected to the transparent electrode 201 formed inside the pixel.

Here, after forming the current control TFT 206, a light-shielding portion 205 formed of a drain wiring is formed. Then, after forming the light shielding portion 205, the transparent electrode 20 is formed.
Form one. Thus, a structure in which the end of the transparent electrode 201 is covered with the light shielding portion 205 can be formed.

In this specification, the light shielding unit 205 is used.
Has been described as being formed on the same surface as the insulating surface on which the transparent electrode 201 is formed, but as shown in FIG.
The case where the transparent electrode 201 is formed so as to cover a part of the transparent electrode 201 is included in this.

Next, an interlayer insulating film 204 made of an insulating film is formed on a part of the transparent electrode 201 and the light-shielding portion 205, and an EL layer 202 and an opaque electrode 2 are formed on the transparent electrode 201.
03 is formed, and finally a passivation film 207 is provided. Thus, the EL module is completed. And
The light emitting device of the present invention can be completed by providing a sealing structure in this EL module so that the EL module can be electrically connected to an external power supply.

[0042]

[Embodiment 1] Here, the present invention is implemented, and a pixel portion and a driving circuit TFT (n-channel type TFT and p-channel type TFT) provided on the periphery of the pixel portion on the same substrate are implemented on the same substrate.
Will be described in detail with reference to FIGS. 3 to 5.

Although the process up to the completion of the EL module is shown here, a method of completing the EL module as a light emitting device will be described in detail in a later embodiment.

First, in this embodiment, Corning # 70
A substrate 300 made of glass such as barium borosilicate glass represented by 59 glass or # 1737 glass, or aluminoborosilicate glass is used. Note that the substrate 300 is not limited as long as it is a light-transmitting substrate, and a quartz substrate may be used. Further, a plastic substrate having heat resistance enough to withstand the processing temperature of this embodiment may be used.

Next, a silicon oxide film is formed on the substrate 300,
A base film 301 including an insulating film such as a silicon nitride film or a silicon oxynitride film is formed. Although a two-layer structure is used as the base film 301 in this embodiment, a single-layer film of the insulating film or a structure in which two or more layers are stacked may be used. For the first layer of the base film 301, a plasma CVD
iH _4, NH _3, a and N ₂ O silicon oxynitride film 301a is formed as the reaction gas 10 to 200 nm (preferably 50 to 100 nm) is formed. In this embodiment, the film thickness 5
0 nm silicon oxynitride film 301a (composition ratio Si = 3
2%, O = 27%, N = 24%, H = 17%). Next, as a second layer of the base film 301, a silicon oxynitride film 301 b formed using SiH ₄ and N ₂ O as a reaction gas by plasma CVD is used to form a 50-200 layer.
nm (preferably 100 to 150 nm). In this embodiment, a 100 nm-thick silicon oxynitride film 301b (composition ratio: Si = 32%, O = 59%, N =
7%, H = 2%).

Next, the semiconductor layers 302 to 30 are formed on the underlying film.
5 is formed. The semiconductor layers 302 to 305 are formed by forming a semiconductor film having an amorphous structure by a known means (sputtering method, LPCV
D method or plasma CVD method)
A crystalline semiconductor film obtained by performing a known crystallization treatment (such as a laser crystallization method, a thermal crystallization method, or a thermal crystallization method using a catalyst such as nickel) is patterned and formed into a desired shape. . The thickness of the semiconductor layers 302 to 305 is 2
It is formed with a thickness of 5 to 80 nm (preferably 30 to 60 nm). The material of the crystalline semiconductor film is not limited, but is preferably silicon or silicon germanium (Si _x Ge).
_It is good to form with _1-X (X = 0.0001-0.02) alloy etc. In this embodiment, a plasma CVD method is used,
After a 55-nm amorphous silicon film was formed, a solution containing nickel was held on the amorphous silicon film. After dehydrogenation (500 ° C., 1 hour) of this amorphous silicon film, thermal crystallization (550 ° C., 4 hours) is performed, and further, laser annealing treatment for improving crystallization is performed. Thus, a crystalline silicon film was formed. Then, semiconductor layers 302 to 305 were formed by patterning the crystalline silicon film by photolithography.

After the formation of the semiconductor layers 302 to 305, a slight amount of impurity element (boron or phosphorus) may be doped in order to control the threshold value of the TFT.

When a crystalline semiconductor film is formed by a laser crystallization method, a pulse oscillation type or continuous emission type excimer laser, a YAG laser, or a YVO ₄ laser can be used. In the case of using these lasers, it is preferable to use a method in which laser light emitted from a laser oscillator is linearly condensed by an optical system and irradiated on a semiconductor film. The crystallization conditions are appropriately selected by the practitioner. When an excimer laser is used, the pulse oscillation frequency is set to 300 Hz, and the laser energy density is set to 100 to 4.
(Typically ^{200~300mJ / cm 2) 00mJ / cm} 2 to.
When a YAG laser is used, it is preferable that the second harmonic is used, the pulse oscillation frequency is 30 to 300 Hz, and the laser energy density is 300 to 600 mJ / cm ² (typically 350 to 500 mJ / cm ² ). And width 100
A laser beam condensed linearly at ~ 1000 μm, for example 400 μm, is irradiated over the entire surface of the substrate, and the superposition rate (overlap rate) of the linear laser light at this time is 50-9.
What is necessary is just to set it as 0%.

Next, a gate insulating film 306 covering the semiconductor layers 302 to 305 is formed. The gate insulating film 306 is formed by a plasma CVD method or a sputtering method and has a thickness of 40 to
The insulating film containing silicon is formed to have a thickness of 150 nm. In this embodiment, a silicon oxynitride film (composition ratio: Si = 32%, O = 59) having a thickness of 110 nm by a plasma CVD method.
%, N = 7%, H = 2%). Needless to say, the gate insulating film is not limited to the silicon oxynitride film, and another insulating film containing silicon may be used as a single layer or a stacked structure.

When a silicon oxide film is used,
TEOS (Tetraethyl Orthosilica) by plasma CVD
te) and O ₂ , a reaction pressure of 40 Pa, and a substrate temperature of 30
It can be formed by discharging at a high-frequency (13.56 MHz) power density of 0.5 to 0.8 W / cm ² at 0 to 400 ° C. The silicon oxide film thus manufactured can obtain good characteristics as a gate insulating film by subsequent thermal annealing at 400 to 500 ° C.

Next, as shown in FIG. 3A, a first conductive film 307 having a thickness of 20 to 100 nm and a second conductive film 30 having a thickness of 100 to 400 nm are formed on the gate insulating film 306.
8 are laminated. In this embodiment, a 30 nm-thick T
a first conductive film 307 made of an aN film and a film thickness of 370 nm
A second conductive film 308 made of a W film was formed by lamination. T
The aN film was formed by a sputtering method, and was sputtered using a Ta target in an atmosphere containing nitrogen. The W film was formed by a sputtering method using a W target. In addition, thermal CV using tungsten hexafluoride (WF ₆ )
It can also be formed by Method D. In any case, it is necessary to lower the resistance in order to use it as a gate electrode,
It is desirable that the resistivity of the W film be 20 μΩcm or less. The resistivity of the W film can be reduced by enlarging the crystal grains. However, when the W film contains many impurity elements such as oxygen, the crystallization is inhibited and the resistance is increased. Therefore, in this embodiment, the W film is formed by a sputtering method using a high-purity W (purity of 99.9999%) target, and further taking into consideration that impurities from the gas phase are not mixed during film formation. By forming, a resistivity of 9 to 20 μΩcm could be realized.

In this embodiment, the first conductive film 307 is used.
Is TaN, and the second conductive film 308 is W. However, the present invention is not particularly limited, and any of Ta, W, Ti, Mo, Al, Cu,
It may be formed of an element selected from Cr and Nd, or an alloy material or a compound material containing the element as a main component.
Alternatively, a semiconductor film typified by a polycrystalline silicon film doped with an impurity element such as phosphorus may be used. Also, A
An alloy composed of g, Pd, and Cu may be used. A first conductive film formed of a tantalum (Ta) film, a second conductive film formed of a W film, a first conductive film formed of a titanium nitride (TiN) film, and a second conductive film formed of a titanium nitride (TiN) film; Are combined with a W film, the first conductive film is formed of a tantalum nitride (TaN) film, and the second conductive film is formed of an Al film, and the first conductive film is formed of a tantalum nitride (TaN) film. Alternatively, a combination of the second conductive film and the Cu film may be used.

Next, as shown in FIG. 3B, resist masks 309 to 309 are formed by photolithography.
12, and a first etching process for forming electrodes and wirings is performed. The first etching process is performed under the first and second etching conditions. In this embodiment, the first etching condition is ICP (Inductively Coupled Platform).
sma: Inductively coupled plasma) etching method, using CF ₄ , Cl _2, and O _{2 as} etching gases, and setting the respective gas flow ratios to 25/25/10 (sccm).
500W RF (13.56MHZ) on coil type electrode at pressure of Pa
z) The plasma was generated by applying power, and etching was performed. Here, a dry etching apparatus (Model E645-IC) using ICP manufactured by Matsushita Electric Industrial Co., Ltd.
P) was used. A 150 W RF (13.56 MHz) power is also applied to the substrate side (sample stage), and a substantially negative self-bias voltage is applied. The W film is etched under the first etching conditions to make the end of the first conductive layer tapered. Under the first etching conditions, the etching rate for W is 200.39 nm / min, the etching rate for TaN is 80.32 nm / min,
The selectivity ratio of W to N is about 2.5. Further, the taper angle of W is about 2 by the first etching condition.
6 °.

Thereafter, as shown in FIG.
Without removing the masks 309 to 312 made of
Change the etching conditions to CF gas for etching._FourAnd Cl_TwoWhen
And the respective gas flow ratios are 30/30 (scc
m) and 500 W of R on the coil-type electrode at a pressure of 1 Pa
F (13.56 MHz) power is applied to generate plasma and about 3
Etching was performed for about 0 seconds. Substrate side (sample stay
20) RF (13.56MHz) power input to
A negative self-bias voltage is applied. CF_FourAnd Cl _TwoTo
Under the mixed second etching condition, the W film and the TaN film
Are etched to the same extent. Under the second etching condition
Etching rate for W is 58.97 nm / mi
n, the etching rate for TaN is 66.43 nm /
min. Note that residue should be left on the gate insulating film
About 10 to 20%
It is good to increase the etching time.

In the first etching process, by making the shape of the resist mask appropriate,
The ends of the first conductive layer and the second conductive layer are tapered due to the effect of the bias voltage applied to the substrate side. The angle of the tapered portion may be 15 to 45 degrees. Thus, the first shape conductive layers 314 to 317 (the first conductive layers 314 a to 317 a and the second conductive layer 314 b) including the first conductive layer and the second conductive layer are formed by the first etching process.
To 317b). Reference numeral 319 denotes a gate insulating film, and a region which is not covered with the first shape conductive layers 314 to 317 is etched by about 20 to 50 nm to form a thinned region.

Then, the resist mask is removed.
First doping processing without adding an n-type semiconductor layer.
The added impurity element is added. (Fig. 3 (B)) Dopin
Can be done by ion doping or ion implantation
Good. The condition of the ion doping method is that the dose amount is 1 × 10¹³
~ 5 × 10^Fifteenatoms / cm^TwoAnd the acceleration voltage is 60 to 100
Performed as keV. In this embodiment, the dose is 1.5 × 1
0^Fifteenatoms / cm^TwoAnd the acceleration voltage is set to 80 keV.
Was. Element belonging to Group 15 as an impurity element imparting n-type
Using arsenic, typically phosphorus (P) or arsenic (As)
However, phosphorus (P) was used here. In this case, the conductive layer 3
14 to 317 are masses for impurity elements imparting n-type.
And the high-concentration impurity regions 320 to 32 are self-aligned.
3 is formed. In the high concentration impurity regions 320 to 323,
1 × 10²⁰~ 1 × 10^{twenty one}atoms / cm ^ThreeN type in the concentration range of
An impurity element to be added is added.

Next, as shown in FIG. 3C, a second etching process is performed without removing the resist mask. Here, CF ₄ , Cl ₂ and O ₂ are used as etching gases.
And the respective gas flow ratios are 25/25/10
(Sccm) and a pressure of 1 Pa applies 50
An RF (13.56 MHz) power of 0 W was applied to generate plasma to perform etching. A 20 W RF (13.56 MHz) power is also applied to the substrate side (sample stage) and a substantially negative self-bias voltage is applied. The etching rate for W in the second etching process is 124.62 nm / mi.
n, the etching rate for TaN is 20.67 nm /
min and the selectivity ratio of W to TaN is 6.05. Therefore, the W film is selectively etched. The taper angle of W became 70 ° by the second etching. By this second etching process, the second conductive layer 32 is formed.
4b to 327b are formed. On the other hand, the first conductive layer 314
a to 318a are hardly etched to form first conductive layers 324a to 328a.

Next, a second doping process is performed. Do
The second conductive layer 324b to 328b is an impurity source.
Used as a mask for silicon, the taper of the first conductive layer
Doping such that the impurity element is added to the semiconductor layer below the part
Ping. In this embodiment, as the impurity element, P (R
Using a dose of 3.5 × 10¹², Acceleration voltage 90k
Plasma doping was performed at eV. Thus, the first
Low concentration impurity regions 329 to 332 overlapping with the conductive layer of
Form yourself. The low concentration impurity regions 329-3
The concentration of phosphorus (P) added to P.32 was 1 × 10¹⁷~ 1
× 10¹⁸atoms / cm ^ThreeAnd the first conductive layer
It has a gentle concentration gradient according to the thickness of the par portion.
Note that the semiconductor layer overlapping the tapered portion of the first conductive layer
And inward from the end of the tapered portion of the first conductive layer.
Although the impurity concentration is slightly lower,
Concentration. Further, the high-concentration impurity regions 333 to 3
The impurity element is also added to the high-concentration impurity region 33.
3 to 336 are formed.

Next, as shown in FIG. 4A, a third etching process is performed without removing the resist mask. In the third etching treatment, the tapered portion of the first conductive layer is partially etched to reduce a region overlapping with the semiconductor layer. The third etching treatment is performed using reactive ion etching (RIE) using CHF ₃ as an etching gas. In this embodiment,
Chamber pressure 6.7 Pa, RF power 800 W, CHF
The third etching process was performed at a flow rate of ₃ gas of 35 sccm. By the third etching, the first conductive layers 341 to 341 to 341
44 are formed.

At the time of the third etching process, the insulating film 319 is also etched at the same time, so that the high-concentration impurity regions 333 are formed.
To 336 are exposed and insulating films 346a to 346d,
347 are formed. In this embodiment, the etching conditions in which a part of the high-concentration impurity regions 333 to 336 are exposed are used. However, if the thickness of the insulating film and the etching conditions are changed, a thin insulating film remains in the high-concentration impurity region. You can also do so.

By the third etching, impurity regions (LDD regions) 337a to 340a which do not overlap with the first conductive layers 341 to 344 are formed. Note that the impurity regions (GOLD regions) 337b to 340b are still overlapped with the first conductive layers 341 to 344.

Further, an electrode formed by the first conductive layer 341 and the second conductive layer 324b becomes a gate electrode of an n-channel TFT of a driving circuit formed in a later step, and becomes a first conductive layer. An electrode formed of the gate electrode 342 and the second conductive layer 325b serves as a gate electrode of a p-channel TFT of a driver circuit formed in a later step. Similarly, the first conductive layer 3
The electrode formed by the second conductive layer 43 and the second conductive layer 326b serves as a gate electrode of an n-channel TFT of a pixel portion formed in a later step, and the first conductive layer 344 and the second conductive layer 32
7b will be the gate electrode of the n-channel TFT of the pixel portion formed in a later step. Further, an electrode formed of the first conductive layer 345 and the second conductive layer 328b serves as one electrode of a storage capacitor of a pixel portion formed in a later step.

Thus, in this embodiment, the impurity regions (GOLD regions) overlapping the first conductive layers 341 to 344 are described.
The difference between the impurity concentration in 337b to 340b and the impurity concentration in the impurity regions (LDD regions) 337a to 340a that do not overlap with the first conductive layers 341 to 344 can be reduced, and the TFT characteristics can be improved.

Next, after removing the mask made of resist, masks 348 and 349 made of resist are newly formed, and a third doping process is performed. Due to this third doping process, the semiconductor layer serving as the active layer of the p-channel TFT has a conductivity type (p-type) opposite to the one conductivity type (n-type).
Region 35 to which an impurity element for imparting (type) is added
0 to 355 are formed. (FIG. 4B) First conductive layer 3
42 and 344 are used as masks for impurity elements,
An impurity element imparting p-type is added to form an impurity region in a self-aligned manner. In this embodiment, the impurity regions 350 to
355 is formed by an ion doping method using diborane (B ₂ H ₆ ). In the third doping process,
The semiconductor layer forming the n-channel TFT is covered with masks 348 and 349 made of resist. Phosphorus is added at different concentrations to the impurity regions 348 and 349 by the first doping process and the second doping process, and the concentration of the impurity element imparting p-type is 2 × in each of the regions. 10 ^{20 to} 2 × 10 ²¹ atom
By doping to s / cm ³ ,
There is no problem because it functions as the source and drain regions of the channel type TFT. In this embodiment,
Since the third etching treatment exposes a part of the semiconductor layer serving as the active layer of the p-channel TFT, there is an advantage that an impurity element (boron) can be easily added.

Through the above steps, impurity regions are formed in the respective semiconductor layers.

Next, a mask 348 made of resist is used.
349 is removed to form a first interlayer insulating film.
To form This insulating film is formed of a silicon-containing insulating film with a thickness of 100 to 200 nm by a plasma CVD method or a sputtering method. In this embodiment, a 150-nm-thick silicon oxynitride film is formed by a plasma CVD method. Needless to say, the insulating film formed here is not limited to the silicon oxynitride film, and another insulating film containing silicon may be used as a single layer or a stacked structure.

Next, as shown in FIG. 4C, a step of activating the impurity element added to each semiconductor layer is performed. This activation step is performed by a thermal annealing method using a furnace annealing furnace. As the thermal annealing method, the oxygen concentration is 400 to 700 ° C. in a nitrogen atmosphere having an oxygen concentration of 1 ppm or less, preferably 0.1 ppm or less, typically 500 to
The activation treatment may be performed at 550 ° C. In this embodiment, the activation treatment is performed by heat treatment at 550 ° C. for 4 hours. Note that, other than the thermal annealing method, a laser annealing method or a rapid thermal annealing method (RTA method) can be applied.

In this embodiment, at the same time as the above-mentioned activation treatment, nickel used as a catalyst at the time of crystallization contains impurity regions (333, 335, 350, 350,
353), the nickel concentration in the semiconductor layer mainly serving as a channel formation region is reduced. A TFT having a channel formation region manufactured in this manner has a low off-current value and high crystallinity, so that a high field-effect mobility can be obtained and favorable characteristics can be achieved.

An activation process may be performed before forming the above-mentioned insulating film. However, when the wiring material used is weak to heat, after forming an interlayer insulating film (an insulating film containing silicon as a main component, for example, a silicon nitride film) for protecting the wiring and the like as in this embodiment, the active material is activated. It is preferable to carry out a chemical treatment.

Further, a heat treatment is performed at 300 to 550 ° C. for 1 to 12 hours in an atmosphere containing 3 to 100% of hydrogen to hydrogenate the semiconductor layer. In this embodiment, heat treatment was performed at 410 ° C. for one hour in a nitrogen atmosphere containing about 3% of hydrogen. In this step, dangling bonds in the semiconductor layer are terminated by hydrogen contained in the interlayer insulating film. As another means of hydrogenation, plasma hydrogenation (using hydrogen excited by plasma) may be performed.

When a laser annealing method is used as the activation treatment, it is preferable to irradiate a laser beam such as an excimer laser or a YAG laser after the above-mentioned hydrogenation.

In this embodiment, as shown in FIG. 5A, an insulating film made of an organic insulating material is formed on an insulating film made of a silicon oxynitride film which has been formed earlier. One interlayer insulating film 357 is formed. In this embodiment, an acrylic resin film having a thickness of 1.6 μm was formed. Next, patterning for forming a contact hole reaching each of the impurity regions 333, 335, 350, 353 is performed.

As the organic insulating material used here, a film made of an organic resin is used, and as the organic resin, a material such as polyimide, polyamide, acrylic, or BCB (benzocyclobutene) can be used. Particularly, an organic insulating material has a strong meaning of flattening, and therefore, acrylic having excellent flatness is preferable. The thickness of the acrylic film is preferably 1 to 5 μm (more preferably 2 to 5 μm).
4 μm). Further, dry etching or wet etching can be used for forming the contact hole.

Then, each of the impurity regions 333, 335, 3
Wirings 358 to 358 to be electrically connected to 50 and 353, respectively.
365 are formed. Note that the wiring 365 formed here
Functions as a light shielding portion in the present invention. Then, a Ti film having a thickness of 50 nm and an alloy film (Al
And an alloy film of Ti and Ti) are formed by patterning, but another conductive film may be used.

As a material specifically used for the light shielding portion, A
It is preferable to use a material having a high reflectance such as 1, Ta, Nb, Mo, and Ag. In addition, as the material having a high reflectance in this specification, a material having a reflectance of 60% or more in a visible light region is preferable, and a material having a reflectance of 80% or more is more preferable. .

When a material having a function of blocking light is used, it is desirable to use a material having a low transmittance.

Next, a transparent conductive film is placed on the
A transparent electrode 367 is formed by patterning with a thickness of 0 nm and patterning. (FIG. 5A) In this example, indium tin oxide (IT) was used as the transparent electrode.
O) 2-20% zinc oxide (Z
A transparent conductive film mixed with nO) is used. As described above, the transparent electrode and the light shielding portion can be formed in the same layer.

The transparent electrode 367 is connected to the drain wiring 3
65 for current control by being formed in contact with
An electrical connection is formed with the drain region of the FT.

Next, as shown in FIG. 5B, an insulating film containing silicon (a silicon oxide film in this embodiment) is formed to a thickness of 500 [nm], and is formed at a position corresponding to the transparent electrode 367. Opening is formed to form second interlayer insulation 368 functioning as a bank
To form When the opening is formed, a tapered side wall can be easily formed by using a wet etching method. Care must be taken because if the side wall of the opening is not sufficiently smooth, deterioration of the EL layer due to the step will become a significant problem.

Next, the EL layer 369 and the cathode (MgAg
The electrode 370 is continuously formed by using a vacuum deposition method without opening to the atmosphere. Note that the thickness of the EL layer 369 is 80 to 20.
0 [nm] (typically 100 to 120 [nm]), cathode 370
Has a thickness of 180 to 300 [nm] (typically 200 to 25 nm).
0 [nm]).

In this step, an EL layer and a cathode are sequentially formed for a pixel corresponding to red, a pixel corresponding to green, and a pixel corresponding to blue. However, since the EL layer has poor resistance to a solution, it must be formed individually for each color without using a photolithography technique. Therefore, it is preferable that a metal mask is used to hide portions other than the desired pixels, and that the EL layer and the cathode are selectively formed only in necessary portions.

That is, first, a mask for hiding all pixels other than pixels corresponding to red is set, and an EL layer for emitting red light is selectively formed using the mask. Next, a mask for hiding all pixels other than pixels corresponding to green is set, and a green light-emitting EL layer is selectively formed using the mask. Next, a mask for covering all pixels other than the pixel corresponding to blue is similarly set, and an EL layer for emitting blue light is selectively formed using the mask. Note that all the masks are described herein as being different, but the same mask may be used again.

Here, a method of forming three types of EL elements corresponding to RGB was used, but a method of combining a white light emitting EL element and a color filter, a blue or blue-green light emitting EL element and a phosphor (fluorescent And a method in which an EL element corresponding to RGB is stacked on a cathode (a counter electrode) using a transparent electrode.

A known material can be used for the EL layer 369. For example, a hole injection layer, a hole transport layer,
The four-layer structure including the light emitting layer and the electron injection layer may be an EL layer.

Further, an EL layer may be formed by spin coating using a known polymer EL material.

Next, a cathode 370 is formed using a metal mask on a pixel having a switching TFT in which a gate electrode is connected to the same gate signal line (a pixel on the same line). In this embodiment, MgAg is used as the cathode 370, but the present invention is not limited to this. As the cathode 370, another known material such as LiF / Al may be used.

Finally, a passivation film 371 made of a silicon nitride film is formed to a thickness of 300 [nm]. By forming the passivation film 371, the EL layer 369 can be protected from moisture and the like, and the reliability of the EL element can be further improved.

Thus, the E of the structure as shown in FIG.
The L module is completed. Note that EL in this embodiment is
In the module manufacturing process, the material forming the gate electrode is T due to the relationship between the circuit configuration and the process.
Although the source signal line is formed by a and W, and the gate signal line is formed by Al which is a wiring material forming the source and drain electrodes, different materials may be used.

A driving circuit 406 having an n-channel TFT 401 and a p-channel TFT 402, a switching TFT 403, and a current control TFT 404
Can be formed over the same substrate.

The n-channel TFT 40 of the drive circuit 406
Reference numeral 1 denotes a channel formation region 372 and a low-concentration impurity region 33 overlapping with a first conductive layer 341 forming a part of a gate electrode.
7b (GOLD region), a low concentration impurity region 337a (LDD region) formed outside the gate electrode, and a high concentration impurity region 3 functioning as a source region or a drain region.
33. The p-channel type TFT 402 has a channel forming region 373 and a first part forming a part of a gate electrode.
Impurity region 338b overlapping with the conductive layer 342, an impurity region 338a formed outside the gate electrode, and an impurity region 334 functioning as a source or drain region.

The switching TFT 40 of the pixel portion 407
3 includes a channel formation region 374 and a low-concentration impurity region 339b overlapping with the first conductive layer 343 forming a gate electrode.
(GOLD region), a low-concentration impurity region 339a (LDD region) formed outside the gate electrode, and a high-concentration impurity region 335 functioning as a source region or a drain region.
have. The channel forming region 375 and the first conductive layer 34 forming a gate electrode are formed in the current controlling TFT 404.
4, a low-concentration impurity region 355 (GOLD region),
Low concentration impurity region 354 formed outside gate electrode
(LDD region) and a high-concentration impurity region 353 functioning as a source region or a drain region. Also,
In this embodiment, a crystalline semiconductor film to which an impurity is added is formed separately from forming a TFT, and this is used as a first electrode, and a conductive film is formed on the first electrode with an insulating film interposed therebetween when a gate electrode is formed. A storage capacitor may be formed by forming a film to serve as the second electrode.

[Embodiment 2] In the embodiment 1, the method of implementing the present invention using the step of forming the transparent electrode after the formation of the light-shielding portion has been described, but the transparent electrode 601 is formed as shown in FIG. After that, a light-blocking portion 605 which also functions as a drain wiring may be provided.

Light shielding part (drain wiring) as in this embodiment
By forming the 605 so as to partially overlap the transparent electrode 601 having a small thickness, an electrical connection between the light-shielding portion (drain wiring) 605 and the transparent electrode 601 is easily formed. Become Note that the configuration of the present embodiment can be freely combined with the configuration of the first embodiment.

[Embodiment 3] FIG. 7 shows the shape of a light-shielding portion formed so as to cover an end portion of a transparent electrode, with respect to its top structure and cross-sectional structure. In this embodiment, the case where the transparent electrode 703 is an anode and the opaque electrode is a cathode will be described.

FIG. 7A is a top view, but the light shielding portion 7 is shown.
Reference numeral 01 denotes a shape that covers the entire end of the anode 702. With such a shape, all light leaking from the end of the anode can be reflected or blocked. The width of the light-shielding portion formed at this time is 2 times the distance x between the adjacent anodes.
Preferably, it occupies at least / 3. Note that an anode 703 illustrated in FIG. 7A is a pixel adjacent to the anode 702. Further, the width of the light-shielding portion here is a length (y + y ') obtained by adding the width (y) of the light-shielding portion of the anode 702 and the width (y') of each light-shielding portion of the anode 703.

Next, FIG. 7B is also a top view.
Different from (A), light shielding portions 711a to
711d. By adopting such a shape, adjacent pixels can also serve as one light-shielding portion. Therefore, when the number of pixels in the pixel portion is increased and the definition is increased, the area of the light-shielding portion occupying the pixel portion is reduced. This is effective because

FIG. 7C shows a cross-sectional shape of the light shielding portion. The cross-sectional structure referred to here refers to the shape of a surface that appears when cut along the line aa ′ in FIGS. 7A and 7B perpendicularly to the paper surface. In addition, a is the anodes 702 and 7
12 and a 'is the distance between anodes 702 and 7
12 inside. In FIG. 7C, the light shielding portion 721
Are formed perpendicular to the EL element formation surface 722 and are in contact with the end of the anode at the light shielding surface 723.

Next, in FIG. 7D, the light shielding portion 731
Are formed in an inversely tapered shape with respect to the EL element forming surface 732, and are in contact with the end of the anode at the light shielding surface 733.

Next, referring to FIG.
Are formed in an uneven shape as shown in the figure with respect to the EL element forming surface 742, and are in contact with the end of the transparent electrode on the light shielding surface 743.

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

[Embodiment 4] In this embodiment, instead of providing the light-shielding portion composed of the drain wiring as shown in Embodiment 1, the second interlayer insulating film provided after the formation of the transparent electrode shown in Embodiment 1 Is formed of a light-shielding insulating material to function as a light-shielding portion. In this embodiment, a case where the transparent electrode is used as an anode and the opaque electrode is used as a cathode will be described.

As the light-shielding insulating material in this embodiment, a material such as black pigment, carbon-containing polyimide, polyamide, acrylic, or BCB (benzocyclobutene) is preferable.

FIG. 8 shows the structure in this embodiment. Here, unlike the first embodiment, the drain wiring can be formed with a small thickness. Thereby, the drain wiring 8
Thus, it is easy to form a part of the transparent electrode 801 on the metal layer 00. Further, since the light-shielding portion is not intentionally provided, it is possible to cope with higher definition of the pixel portion.

After forming the anode 801, a light-shielding second interlayer insulating film 805 is provided, and the EL layer 802 and the cathode 80
3 and the passivation film 806 are stacked to complete the structure of this embodiment. Note that the current control TFT 807 shown here may be the same as that shown in the first embodiment.

The structure of this embodiment can be freely combined with the structures of Embodiments 1 to 3.

[Embodiment 5] In this embodiment, a case where the present invention is implemented in a TFT having a structure different from that shown in Embodiment 1 will be described with reference to FIGS.

As shown in FIG. 9, a current controlling TFT 906 is formed on an insulating surface. In the first embodiment, the structure in which the connection wiring between the current controlling TFT and the transparent electrode is formed after the formation of the first interlayer insulating film is described. In the present embodiment, the current control is performed after the formation of the first interlayer insulating film. A case where a structure obtained by forming a connection wiring between a TFT for use and a transparent electrode and forming a transparent electrode after forming a second interlayer insulating film is used in this embodiment will be described. The method for manufacturing the light emitting device in this embodiment will be described later in detail. In this embodiment, a case will be described in which the transparent electrode is an anode and the opaque electrode is a cathode.

As shown in FIG. 9, the current controlling TFT 906
After forming the anode 901 electrically connected to the
The light-shielding portion 905 is formed by a sputtering method so as not to come into contact with 01. At this time, a material having a high reflectivity such as Al, Ta, Nb, Mo, or Ag is preferable as a material of the light shielding portion 905. In this embodiment, the light shielding portion is formed using Ag.

The thickness of the light shielding portion 905 is 10.
The thickness is preferably from 0 to 800 nm, more preferably from 300 to 800 nm.
It is preferable to set it to 600 nm. In this embodiment, the anode 901 and the light-shielding portion 905 need to be formed so as not to be in contact with each other.

In this embodiment, after the anode 901 is formed first, the light shielding portion 905 is formed.
05 may be formed first. And the anode 9
After forming the light-shielding portion 905 and the EL layer 902, the EL layer 902 and the cathode 903 are formed. Finally, a passivation film 907 made of an insulating material is formed to complete the EL module.

Next, the structure of the EL module shown in this embodiment will be described with reference to the sectional structure of FIG.

In FIG. 10, reference numeral 11 denotes a substrate, and 12 denotes an insulating film serving as a base (hereinafter, referred to as a base film). Substrate 11
A light-transmitting substrate, typically, a glass substrate, a quartz substrate, a glass ceramic substrate, or a crystallized glass substrate can be used. However, it must withstand the maximum processing temperature during the manufacturing process. Further, a plastic substrate may be used as long as it has heat resistance enough to withstand the processing temperature of this embodiment.

The base film 12 is particularly effective when a substrate containing mobile ions or a substrate having conductivity is used, but may not be provided on a quartz substrate. As the base film 12, an insulating film containing silicon (silicon) may be used. Note that, in this specification, the term “insulating film containing silicon” refers specifically to silicon such as a silicon oxide film, a silicon nitride film, or a silicon nitride oxide film (SiOxNy: x and y are arbitrary integers). On the other hand, it refers to an insulating film containing oxygen or nitrogen at a predetermined ratio.

Reference numeral 1001 denotes a switching TFT.
Although the switching TFT is formed by an n-channel TFT, the switching TFT may be a p-channel TFT. Also, 100
2 is a current control TFT, and FIG.
The case where the FT 1002 is formed by a p-channel TFT is shown. That is, in this case, the current controlling TFT 1
The drain electrode 002 is connected to the anode of the EL element. However, when the current control TFT is formed of an n-channel TFT, the current control TFT is connected to the cathode of the EL element.

The field-effect mobility of an n-channel TFT is p
Because it is larger than the field effect mobility of the channel type TFT,
The operating speed is fast and a large current is easy to flow. Further, even when the same amount of current flows, the TFT size can be made smaller in the n-channel TFT.

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

The switching TFT 1001 includes a source region 13, a drain region 14, and LDD regions 15a to 15a.
d, an active layer including the isolation region 16 and the channel formation regions 17a and 17b, the gate insulating film 18, and the gate electrodes 19a and 19a.
9b, a first interlayer insulating film 20, a source wiring 21, and a drain wiring 22. Note that the gate insulating film 18 or the first interlayer insulating film 20 may be common to all TFTs on the substrate, or may be different depending on the circuit or element.

The switching TFT 1001 is electrically connected to the gate electrodes 19a and 19b, and has a so-called double gate structure. Of course, not only a double gate structure but also a so-called multi-gate structure (a structure including an active layer having two or more channel forming regions connected in series) such as a triple gate structure may be used.

The multi-gate structure is extremely effective in reducing the off-state current. If the off-state current of the switching TFT is sufficiently reduced, a capacitor (not shown) will be used.
Required capacity can be reduced. That is, since the area occupied by the capacitor can be reduced, a multi-gate structure is effective in increasing the effective light emitting area of the EL element.

Further, in the switching TFT 1001, the LDD regions 15a to 15d are
The gate electrodes 19a and 19b are provided so as not to overlap with the gate electrodes 19a and 19b. Such a structure is very effective in reducing off-state current. The length (width) of the LDD regions 15a to 15d is 2.0 to 12.0 μm, typically 6.0 to 1 μm.
The thickness may be 0.0 μm.

Note that it is more preferable to provide an offset region (a region formed of a semiconductor layer having the same composition as the channel formation region and to which a gate voltage is not applied) between the channel formation region and the LDD region in order to reduce off-state current. Also,
In the case of a multi-gate structure having two or more gate electrodes, an isolation region 16 provided between channel formation regions
(A region where the same impurity element is added at the same concentration as the source region or the drain region) is effective in reducing off-state current.

Next, the current control TFT 1002 includes the source region 26, the drain region 27, and the channel formation region 2.
9, a gate insulating film 18, a gate electrode 30, a first interlayer insulating film 20, a source wiring 31 and a drain wiring 32. The gate electrode 30 has a single gate structure, but may have a multi-gate structure.

The drain region of the switching TFT is connected to the gate of the current control TFT. Specifically, the gate electrode 30 of the current controlling TFT 1002 is electrically connected to the drain region 14 of the switching TFT 1001 via a drain wiring (also referred to as a connection wiring) 22.

Further, from the viewpoint of increasing the amount of current that can flow, the thickness of the active layer (particularly, the channel formation region) of the current controlling TFT 1002 is increased (preferably 5).
(0 to 100 nm, more preferably 60 to 80 nm) is also effective. Conversely, the switching TFT 1001
In the case of, from the viewpoint of reducing the off current,
The thickness of the active layer (particularly, the channel formation region) is reduced (preferably 20 to 50 nm, more preferably 25 to 40).
nm) is also effective.

In the above, the structure of the TFT provided in the pixel has been described. At this time, a driving circuit is also formed at the same time. FIG. 10 shows a CM as a basic unit for forming a drive circuit.
The OS circuit is shown.

In FIG. 10, a TFT having a structure for reducing hot carrier injection while keeping the operating speed as low as possible is replaced with an n-channel TFT 10 of a CMOS circuit.
04. Note that a driving circuit here refers to a data signal driving circuit and a gate signal driving circuit.
Of course, other logic circuits (such as a level shifter, an A / D converter, and a signal dividing circuit) can be formed.

The active layer of the n-channel type 1004 includes a source region 35, a drain region 36, an LDD region 37, and a channel forming region 38. The LDD region 37 overlaps with the gate electrode 39 via the gate insulating film 18. In this specification, the LDD region 37 is also called a Lov region.

The reason why the LDD region is formed only on the drain region side is to avoid lowering the operation speed.
In addition, the n-channel TFT 1004 does not need to care much about the off-current value, and it is better to emphasize the operation speed. Therefore, it is desirable that the LDD region 37 is completely overlapped with the gate electrode and the resistance component is reduced as much as possible. That is, it is better to eliminate the so-called offset.

Also, a p-channel type TFT of a CMOS circuit
In the case of 1005, there is almost no concern about deterioration due to hot carrier injection, so that an LDD region need not be particularly provided. Therefore, the active layer includes the source region 40, the drain region 41, and the channel forming region 42, and the gate insulating film 1 is formed thereon.
8 and a gate electrode 43 are provided. Needless to say, it is also possible to provide an LDD region similarly to the n-channel TFT 1004 and take measures against hot carriers.

The n-channel TFT 1004 and the p-channel TFT
Each of the channel type TFTs 1005 has a first interlayer insulating film 2
0, source wirings 44 and 45 are formed. Both are electrically connected by the drain wiring 46. Then, a first passivation film 47 is formed thereon.

Reference numeral 48 denotes a second interlayer insulating film, TF
It has a function as a flattening film for flattening a step formed by T. As the second interlayer insulating film 48, an organic resin film is preferable, and polyimide, polyamide, acrylic, B
It is preferable to use CB (benzocyclobutene) or the like. These organic resin films have an advantage that a good flat surface is easily formed and the relative dielectric constant is low. Since the EL layer is very sensitive to irregularities, it is desirable that the step due to the TFT is almost completely absorbed by the second interlayer insulating film. In order to reduce the parasitic capacitance formed between the gate wiring or data wiring and the cathode of the EL element, it is desirable to provide a thick material having a low relative dielectric constant. Therefore, the film thickness is preferably 0.5 to 5 μm (preferably 1.5 to 2.5 μm).

Next, the light shielding portion 51 is formed by patterning. As a material for forming the light shielding portion 51, a material having a light reflectance of 60% or more in a visible light region is preferably used, and more preferably, a light reflectance of 80%.
It is preferable to use the above materials. In particular,
Ag, Al, Ta, Nb, Mo, Cu, Mg, Ni, P
In this embodiment, the light shielding portion 51 is provided at a position where the light shielding portion 51 does not touch the edge of the pixel.

Reference numeral 49 denotes an anode made of an oxide conductive film (anode of an EL element). After a contact hole (opening) is formed in the second interlayer insulating film 48, current control is performed at the formed opening. It is formed so as to be connected to the drain wiring 32 of the TFT 1002 for use.

The EL layer 52 is provided on the anode 49. Although the EL layer 52 is used in a single layer or a laminated structure, the luminous efficiency is better when used in a laminated structure. Generally, a hole injection layer / a hole transport layer / a light emitting layer / an electron transport layer are formed in this order on a transparent electrode.
Or a hole injection layer / a hole transport layer / a light emitting layer / an electron transport layer /
A structure like an electron injection layer may be used. In the present invention, any known structure may be used, and the EL layer may be doped with a fluorescent dye or the like.

As the organic EL material, for example, the materials disclosed in the following US patents or publications can be used. U.S. Patent No. 4,356,429, U.S. Patent No. 4,539,507, U.S. Patent No. 4,720,43
No. 2, U.S. Pat. No. 4,769,292; U.S. Pat. No. 4,885,211; U.S. Pat. No. 4,950,9
No. 50, U.S. Pat. No. 5,059,861, U.S. Pat. No. 5,047,687, U.S. Pat.
No. 446, U.S. Pat. No. 5,059,862, U.S. Pat. No. 5,061,617, U.S. Pat.
No. 1,629, U.S. Pat. No. 5,294,869, U.S. Pat. No. 5,294,870, JP-A-10-1895
No. 25, JP-A-8-241048, JP-A-8-241048
-78159.

The light emitting device can be roughly divided into four color display methods, a method of forming three kinds of EL elements corresponding to R (red), G (green), and B (blue), and a method of forming a white light emitting element.
A method in which an L element and a color filter are combined, a blue or blue-green light emitting EL element and a phosphor (fluorescent color conversion layer: C
CM) and a method in which a transparent electrode is used as a cathode and EL elements corresponding to RGB are stacked.

The cathode 53 of the EL element is provided on the EL layer 52. As the cathode 53, a material containing magnesium (Mg), lithium (Li), or calcium (Ca) having a small work function is used. Preferably Mg: Ag
(Material in which Mg and Ag are mixed at Mg: Ag = 10: 1)
May be used. Other examples include a Mg: Ag: Al electrode, a Li: Al electrode, and a LiF: Al electrode.

After forming the EL layer 52, the cathode 53 is preferably formed continuously without opening to the atmosphere. Cathode 5
This is because the state of the interface between 3 and the EL layer 52 greatly affects the luminous efficiency of the EL element. In this embodiment, the anode 4
9. The light emitting element formed by the EL layer 52 and the cathode 53 is E
Called L element 1003.

The laminate comprising the EL layer 52 and the cathode 53 is
Although it is necessary to form the EL layer 52 individually for each pixel, the EL layer 52 is extremely weak against moisture, so that ordinary photolithography cannot be used. Therefore, it is preferable to selectively form the film by a vapor phase method such as a vacuum evaporation method, a sputtering method, and a plasma CVD method using a physical mask material such as a metal mask.

As a method for selectively forming the EL layer 52, an ink jet method, a screen printing method, or the like can be used.

Reference numeral 54 denotes a protective electrode which protects the cathode 53 from external moisture and the like, and at the same time, the cathode 53 of each pixel.
Is an electrode for connecting. As the protection electrode 54,
Aluminum (Al), copper (Cu) or silver (Ag)
It is preferable to use a low-resistance material containing The protective electrode 54 can also be expected to have a heat radiation effect of reducing heat generation of the EL layer. After forming the EL layer 52 and the cathode 53,
It is also effective to form up to the protection electrode 54 continuously without opening to the atmosphere.

Further, a passivation 55 made of an insulating material is formed on the protective electrode 54, and the passivation 55 in this embodiment is formed.
Complete the L module.

The structure of this embodiment can be freely combined with the structures of Embodiments 1 to 4.

[Embodiment 6] In this embodiment, the case of using an EL module having a different TFT structure from that shown in Embodiment 5 will be described with reference to FIG. That is, in this embodiment, an example using a bottom gate type TFT will be described. In the case of the present embodiment, the wiring cannot be used as a light-shielding portion due to the structure, so that a new light-shielding portion is provided. In this embodiment, a case will be described in which the transparent electrode is an anode and the opaque electrode is a cathode.

In FIG. 11, only the current controlling TFT among the pixel TFTs will be described. 1101 is a substrate,
Reference numeral 1102 denotes an insulating film serving as a base (hereinafter, referred to as a base film). As the substrate 1101, a light-transmitting substrate, typically, a glass substrate, a quartz substrate, a glass ceramic substrate, or a crystallized glass substrate can be used. However, it must withstand the maximum processing temperature during the manufacturing process.

Although the base film 1102 is particularly effective when a substrate containing mobile ions or a substrate having conductivity is used, the base film 1102 need not be provided on a quartz substrate. Underlayer 11
As 02, an insulating film containing silicon (silicon) may be used. In this specification, “an insulating film containing silicon”
Specifically, oxygen or nitrogen is contained at a predetermined ratio with respect to silicon such as a silicon oxide film, a silicon nitride film, or a silicon nitride oxide film (SiOxNy: x and y are represented by arbitrary integers). Refers to an insulating film.

Reference numeral 1103 denotes a current control TFT, which is formed by a p-channel TFT. When the EL emission direction is the lower surface of the substrate (the surface on which the TFT and the EL layer are not provided), the switching TFT is formed by an n-channel TFT, and the current control TFT is formed by a p-channel TFT. Preferably, there is. However, the present invention is not limited to this configuration. The switching TFT and the current control TFT are n-channel TFTs or p-channel TFs.
T or both.

The current controlling TFT 1103 includes an active layer including a source region 1104, a drain region 1105, and a channel forming region 1106, a gate insulating film 1107, a gate electrode 1108, a first interlayer insulating film 1109, and a wiring (1). 1111 and the wiring (2) 1111 are formed. In this embodiment, the current control TFT 1103 is a p-channel TFT.

Although not shown, the drain region of the switching TFT is connected to the gate electrode 1108 of the current control TFT 1103. Specifically, a gate electrode 1108 of the current controlling TFT 1103 is electrically connected to a drain region (not shown) of the switching TFT via a drain wiring (not shown). Note that the gate electrode 1108 has a single gate structure, but may have a multi-gate structure. The wiring (2) 1111 of the current controlling TFT 1103 is connected to a current supply line (not shown).

The current controlling TFT 1103 is an element for controlling the amount of current injected into the EL element, and a relatively large amount of current flows. Therefore, it is preferable that the channel width (W) is designed to be larger than the channel width of the switching TFT. It is preferable that the channel length (L) is designed to be longer so that an excessive current does not flow through the current controlling TFT 1103. Desirably 0.5 per pixel
２2 μA (preferably 1 to 1.5 μA).

Further, the thickness of the active layer (particularly, the channel formation region) of the current controlling TFT 1103 is increased (preferably 50 to 100 nm, more preferably 60 to 8 nm).
0 nm), deterioration of the TFT may be suppressed.

Up to this point, the structural differences between the TFT shown in the fifth embodiment and the inverted stagger type TFT are described. Thereafter, the present invention can be carried out in the same manner as in the fifth embodiment.

That is, after forming the current control TFT 1103, a first interlayer insulating film and a second interlayer insulating film are formed, and an anode 1113 electrically connected to the current control TFT 1103 is formed. Then, after the anode 1113 is formed, the light shielding portion 1112 is formed.

As a material specifically used for the light shielding portion, A
It is preferable to use a material having a high reflectance such as 1, Ta, Nb, Mo, and Ag. In addition, as the material having a high reflectance in this specification, a material having a reflectance of 60% or more in a visible light region is preferable, and a material having a reflectance of 80% or more is more preferable. .

In the case of using a material having a function of blocking light, it is desirable to use a material having a low transmittance.

The light shielding portion 1112 is formed by patterning after being formed by a sputtering method.

Next, an EL layer 1114 and a cathode 1115 are formed, and a passivation film made of an insulating material is formed on the cathode 1115, whereby an EL module having an inverted staggered TFT structure can be formed.

The configuration of this embodiment can be freely combined with the configurations of Embodiments 1 to 5.

[Embodiment 7] In this embodiment, a method will be described in which an EL module having a light shielding portion or a function of blocking light in the above embodiments is further completed as a light emitting device. In this embodiment, a case where the transparent electrode is used as an anode and the opaque electrode is used as a cathode will be described.

FIG. 12A is a top view showing a state in which the process up to sealing of the EL element has been performed, and FIG. 12B is a cross-sectional view taken along line AA ′ of FIG. 12A. 12 shown by dotted line
01 is a source side driving circuit, 1202 is a pixel portion, 1203
Is a gate side drive circuit. Reference numeral 1204 denotes a cover material, 1205 denotes a first seal material, 1206 denotes a second seal material, and a sealing material 1207 is provided inside a region surrounded by the first seal material 1205.

Note that reference numeral 1208 denotes a source side drive circuit 120.
1 and a wiring for transmitting a signal input to the gate side driving circuit 1203, and an FPC which is an external input terminal.
(Flexible print circuit) 1209 receives a video signal and a clock signal. Note that here, FP
Although only C is shown, a printed wiring board (PWB) may be attached to this FPC. The EL display device in this specification includes not only the EL display device main body but also a state in which an FPC or a PWB is attached thereto.

Next, a cross-sectional structure will be described with reference to FIG. The pixel portion 120 is provided above the substrate 1210.
2. A gate side driver circuit 1203 is formed, and the pixel portion 1202 is formed by a plurality of pixels including a current control TFT 1211 and a transparent electrode 1212 electrically connected to a drain thereof. In addition, the gate side driving circuit 1203
Is an n-channel TFT 1213 and a p-channel TFT 1
It is formed using a CMOS circuit (see FIG. 5) in which the C.N.

At both ends of the anode 1212, banks 1215 are formed. On the anode 1212, the EL layers 1216 and E
The cathode 1217 of the L element is formed.

The cathode 1217 also functions as a wiring common to all pixels, and is connected to the FPC 1209 via the connection wiring 1208.
Is electrically connected to Further, the elements included in the pixel portion 1202 and the gate side driver circuit 1203 are all covered with the cathode 1217 and the passivation film 1218.

The cover member 1204 is attached to the first seal member 1205. In addition, the cover material 12
A spacer made of a resin film may be provided in order to secure an interval between the element 04 and the EL element. Then, the first sealing material 12
The inside of 05 is filled with a sealing material 1207. Note that an epoxy resin is preferably used for the first sealant 1205 and the sealant 1207. Further, it is desirable that the first sealant 1205 be a material that does not transmit moisture and oxygen as much as possible. Further, a substance having a moisture absorbing effect or a substance having an effect of preventing oxidation may be contained in the sealing material 1207.

[0166] The sealing material 1207 provided so as to cover the EL element also functions as an adhesive for bonding the cover material 1204. In the present embodiment, the cover material 120 is used.
As a material of a plastic substrate constituting FRP (FRP (Fi
berglass-Reinforced Plastics), PVF (polyvinyl fluoride), mylar, polyester or acrylic can be used.

Further, the cover material 1 is formed by using the sealing material 1207.
After bonding 204, the side surface (exposed surface) of sealing material 1207
The second sealing material 1206 is provided so as to cover. The same material as the first sealant 1205 can be used for the second sealant 1206.

With the above structure, the EL element is sealed with the sealing material 12.
By encapsulating the EL element in 07, the EL element can be completely shut off from the outside, and a substance such as moisture or oxygen that promotes deterioration of the EL layer due to oxidation can be prevented from entering from the outside. Therefore, a highly reliable light-emitting device can be obtained.

The structure of this embodiment can be freely combined with the structures of Embodiments 1 to 6.

[Embodiment 8] Since the light emitting device of the present invention is a self-luminous type, it has excellent visibility in a bright place and a wide viewing angle as compared with a liquid crystal display. Therefore, it can be used as a display portion of various electric appliances. For example, T
In order to watch V broadcasts or the like on a large screen, the light emitting device of the present invention is preferably used in a display portion of a display having a diagonal of 30 inches or more (typically 40 inches or more).

Note that the display shown in this embodiment includes:
All information display devices such as a personal computer display device, a TV broadcast reception display device, and an advertisement display device are included. In addition, the light emitting device of the present invention can be used for display portions of various electric appliances.

Examples of such an electric appliance of the present invention include a video camera, a digital camera, a goggle type display device (head mounted display), a navigation system,
Sound playback devices (car audio, audio components, etc.), notebook personal computers, game machines,
A portable information terminal (a mobile computer, a mobile phone, a portable game machine, an electronic book, or the like), and an image reproducing apparatus provided with a recording medium (specifically, a digital video disc (DV
D) and the like, a device having a display capable of reproducing a recording medium and displaying its image). In particular, for a portable information terminal that is often viewed from an oblique direction, a wide viewing angle is regarded as important, and it is desirable to use an EL display. FIGS. 13 and 14 show specific examples of these electric appliances.
Shown in

FIG. 13A shows an EL display.
A housing 1301, a support 1302, a display unit 1303, and the like are included. The light emitting device of the present invention can be used for the display portion 1303. Note that the light-emitting device of the present invention is a self-luminous type, and does not require a backlight, and can be a display portion thinner than a liquid crystal display.

FIG. 13B shows a video camera, which includes a main body 1311, a display unit 1312, an audio input unit 1313, operation switches 1314, a battery 1315, and an image receiving unit 131.
6 and so on. The light emitting device of the present invention can be used for the display portion 1312.

FIG. 13C shows a part (one side on the right) of the head mounted EL display, which includes a main body 1321, a signal cable 1322, a head fixing band 1323, and a display unit 13.
24, an optical system 1325, a display device 1326, and the like. The light emitting device of the present invention can be used for the display device 1326.

FIG. 13D shows an image reproducing apparatus (specifically, a DVD reproducing apparatus) provided with a recording medium.
1, recording medium (DVD, etc.) 1332, operation switch 13
33, a display unit (a) 1334, a display unit (b) 1335, and the like. The display unit (a) 1334 mainly displays image information, and the display unit (b) 1335 mainly displays character information. The light emitting device of the present invention employs these display units (a) 133.
4. Can be used in the display portion (b) 1335. Note that the image reproducing device provided with the recording medium includes a home game machine and the like.

FIG. 13E shows a goggle type display device (head mounted display), which includes a main body 1341, a display portion 1342, and an arm portion 1343. The light-emitting device of the present invention can be used for the display portion 1342.

FIG. 13F shows a personal computer, which includes a main body 1351, a housing 1352, a display portion 1353,
A keyboard 1354 and the like. The light emitting device of the present invention can be used for the display portion 1353.

If the emission luminance of the EL material becomes high in the future, it becomes possible to enlarge and project the light containing the output image information with a lens or the like and use it for a front type or rear type projector.

In addition, the above-mentioned electric appliances are available on the Internet or C
Information distributed through an electronic communication line such as an ATV (cable television) is frequently displayed, and in particular, opportunities to display moving image information are increasing. Since the response speed of the EL material is extremely high, the light emitting device of the present invention is preferable for displaying moving images.

FIG. 14A shows a portable telephone,
01, audio output unit 1402, audio input unit 1403, display unit 1404, operation switch 1405, antenna 1406
including. The light-emitting device of the present invention can be used for the display portion 1404. Note that the display portion 1404 can reduce power consumption of the mobile phone by displaying white characters on a black background.

FIG. 14B shows a sound reproducing device, specifically, a car audio.
2, including operation switches 1413 and 1414. The light emitting device of the present invention can be used for the display portion 1412. In this embodiment, the in-vehicle audio is shown, but the present invention may be applied to a portable or home-use audio reproducing apparatus. The display unit 1
The power consumption 414 can be suppressed by displaying white characters on a black background. This is particularly effective in a portable sound reproducing device.

FIG. 14C shows a digital camera, which includes a main body 1421, a display unit (A) 1422, an eyepiece unit 1423,
An operation switch 1424, a display portion (B) 1425, and a battery 1426 are included. The light emitting device of the present invention can be used for the display portion (A) 1422 and the display portion (B) 1425. In the case where the display portion (B) 1425 is mainly used as an operation panel, power consumption can be reduced by displaying white characters on a black background.

In the portable electric appliance shown in this embodiment, the method for reducing power consumption is as follows.
A method of providing a sensor unit for sensing external brightness and adding a function such as lowering the brightness of the display unit when used in a dark place is exemplified.

As described above, the applicable range of the present invention is extremely wide, and the present invention can be used for electric appliances in various fields. Further, any configuration shown in the first to seventh embodiments may be applied to the electric appliance of the present embodiment.

[0186]

According to the present invention, by providing a light-shielding portion at the end of the transparent electrode of the EL element, light that is to be emitted from the transparent electrode toward the light-shielding portion is blocked. As a result, it is possible to prevent light loss due to light emitted from the EL layer from escaping from the end of the transparent electrode and light leakage to an adjacent pixel, thereby greatly improving light extraction efficiency.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a light shielding unit of the present invention.

FIG. 2 is a diagram illustrating a cross-sectional structure in the vicinity of a pixel of a light-emitting device.

FIG. 3 is a diagram illustrating a manufacturing process of a light-emitting device.

FIG. 4 is a diagram showing a manufacturing process of a light-emitting device.

FIG. 5 is a diagram showing a manufacturing process of a light-emitting device.

FIG. 6 is a diagram illustrating a cross-sectional structure near a pixel of a light-emitting device.

FIG. 7 is a diagram showing details of a light shielding unit.

FIG. 8 is a diagram showing a cross-sectional structure near a pixel of a light-emitting device.

FIG. 9 illustrates a cross-sectional structure in the vicinity of a pixel of a light-emitting device.

FIG. 10 illustrates a cross-sectional structure of a light-emitting device.

FIG. 11 illustrates a cross-sectional structure in the vicinity of a pixel of a light-emitting device.

FIG. 12 illustrates an appearance of a light-emitting device.

FIG. 13 illustrates an example of an electric appliance.

FIG. 14 illustrates an example of an electric appliance.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05B 33/26 H05B 33/26 Z 33/28 33/28 F term (Reference) 3K007 AB03 AB04 AB13 AB18 BA06 CA01 CA02 CA05 CB01 DA00 DB03 EA04 EB00 FA01 FA02 5C094 AA10 AA16 BA29 CA19 DA14 DA15 DB04 EA04 EA05 EA06 EA07 EB02 ED11 ED15 FB12 FB14 FB15 FB16 HA02 HA03 HA04 HA06 HA08 HA10

Claims (20)

[Claims] 1. A light emitting device comprising: a transparent electrode formed on an insulating surface; an EL layer formed on the transparent electrode; and an opaque electrode formed on the EL layer. A light-emitting device formed on the insulating surface. 2. A transparent electrode formed on an insulating surface; a light-shielding portion formed on the insulating surface; an EL layer formed on the transparent electrode; and an opaque electrode formed on the EL layer. The light-emitting device according to claim 1, wherein the light-shielding portion is formed in contact with the transparent electrode. 3. A light emitting device comprising: a plurality of transparent electrodes formed on an insulating surface; an EL layer formed on the transparent electrode; and an opaque electrode formed on the EL layer. A light emitting device, wherein a portion is also formed on the insulating surface. 4. A plurality of transparent electrodes formed on an insulating surface, a light-shielding portion formed on the insulating surface, an EL layer formed on the transparent electrode, and a plurality of transparent electrodes formed on the EL layer. A light emitting device having an opaque electrode, wherein the light shielding portion is formed in contact with the transparent electrode. 5. A plurality of transparent electrodes formed on an insulating surface; a light-shielding portion formed on the insulating surface; an EL layer formed on the transparent electrode; A light emitting device having an opaque electrode, wherein the light shielding portion is formed in contact with at least two of the transparent electrodes. 6. The light-emitting device according to claim 1, wherein the light-shielding portion is made of an insulating film containing pigment or carbon. 7. The light emitting device according to claim 1, wherein the light shielding portion is made of a conductive material having high reflectance. 8. The light emitting device according to claim 7, wherein the light shielding portion reflects light generated in the EL layer. 9. A transparent electrode connected to the thin film transistor via a wiring and formed on an insulating surface, an EL layer formed on the transparent electrode, and an opaque electrode formed on the EL layer. The light-emitting device according to claim 1, wherein a light-shielding portion is also formed on the insulating surface. 10. A transparent electrode connected to a thin film transistor via a wiring and formed on an insulating surface, a light-shielding portion formed on the insulating surface, and an EL layer formed on the transparent electrode. A light-emitting device having an opaque electrode formed on the EL layer, wherein the light-shielding portion is formed in contact with the transparent electrode. 11. A transparent electrode connected to the thin film transistor via a wiring and formed on an insulating surface, an EL layer formed on the transparent electrode, and an opaque electrode formed on the EL layer. A light emitting device in which a plurality of pixels are formed, wherein a light shielding portion is also formed on the insulating surface. 12. A transparent electrode connected to the thin film transistor via a wiring and formed on an insulating surface, a light-shielding portion formed on the insulating surface, and an EL layer formed on the transparent electrode. A light emitting device in which a plurality of pixels each having an opaque electrode formed on the EL layer are formed, wherein the light blocking portion is formed in contact with the transparent electrode. 13. A transparent electrode connected to a thin film transistor via a wiring and formed on an insulating surface, a light shielding portion formed on the insulating surface, and an EL layer formed on the transparent electrode. A light emitting device in which a plurality of pixels each having an opaque electrode formed on the EL layer are formed, wherein the light shielding portion is formed in contact with at least two of the transparent electrodes. apparatus. 14. The light emitting device according to claim 13, wherein said plurality of pixels are adjacent pixels. 15. The light emitting device according to claim 9, wherein said light shielding portion is made of an insulating film containing pigment or carbon. 16. A light emitting device according to claim 9, wherein said light shielding portion is a wiring and is made of a conductive material having a high reflectance. 17. The light emitting device according to claim 16, wherein the light shielding portion reflects light generated in the EL layer. 18. The light emitting device according to claim 1, wherein the transparent electrode is an anode, and the opaque electrode is a cathode. 19. The light emitting device according to claim 1, wherein the light shielding portion is made of a metal material having a reflectance of 60% or more. 20. An electric appliance using the light emitting device according to claim 1 as a display unit or a light source.