JP2004006332A - Semiconductor device and its fabrication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor device having a structure in which the extraction amount of light emission in a certain one direction is made to be increased in a light-emitting element, and to provide its fabrication method. <P>SOLUTION: In this device, a field effect transistor (FET) is formed on a semiconductor substrate, a curved face having a radius of curvature is formed at the upper end part of an insulator 19, part of first electrodes 18c, 18d is exposed corresponding to the curved face, and a slope is formed. Etching treatment is carried out so that a first electrode 18b is exposed in a region to become a light emission region. The light emission from an organic compound layer 20 is reflected at the slope of the first electrodes 18c, 18d, and the total extraction amount of light emission in the arrow-direction shown in Fig. 1 (A) is made increased. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a semiconductor device having a circuit including a field effect transistor (hereinafter, referred to as an FET) and a manufacturing method thereof. In this specification, the term “FET” refers to any element that is an element based on the basic principle of an FET, such as a MIS • FET, a MOS • FET using an oxide as an insulator film, and a thin film transistor using a semiconductor thin film ( TFT). In particular, the present invention relates to an electronic device in which a semiconductor device having an organic light emitting diode (OLED) is mounted as a component.
[0002]
Note that in this specification, a semiconductor device generally means a device that can function by utilizing semiconductor characteristics, and an electro-optical device, a light-emitting device, a semiconductor circuit, and an electronic device are all semiconductor devices.
[0003]
Further, a module in which a connector, for example, an FPC (Flexible printed circuit) or TAB (Tape Automated Bonding) tape or a TCP (Tape Carrier Package) is attached to the light emitting device, or a module in which a printed wiring board is provided at the tip of the TAB tape or TCP Alternatively, the semiconductor device includes all modules in which an IC (integrated circuit) is directly mounted on a light-emitting element by a COG (Chip On Glass) method.
[0004]
[Prior art]
In recent years, research on a light emitting device having an EL element as a self-luminous element has been actively conducted, and in particular, a light emitting device using an organic material as an EL material has attracted attention. This light emitting device is also called an organic EL display (OELD: Organic EL Display) or an organic light emitting diode (OLED: Organic Light Emitting Diode). Note that a light-emitting device in this specification refers to an image display device, a light-emitting device, or a light source (including a lighting device).
[0005]
Note that the EL element includes a layer containing an organic compound capable of obtaining luminescence (Electro Luminescence) generated by application of an electric field (hereinafter, referred to as an EL layer), an anode, and a cathode. Luminescence of an organic compound includes light emission (fluorescence) when returning from a singlet excited state to a ground state and light emission (phosphorescence) when returning to a ground state from a triplet excited state. The light-emitting device manufactured by the film formation method can be applied to the case where either light emission is used.
[0006]
Unlike a liquid crystal display device, a light emitting device is of a self-luminous type and has a feature that there is no problem of a viewing angle. That is, as a display used outdoors, it is more suitable than a liquid crystal display, and its use in various forms has been proposed.
[0007]
An EL element has a structure in which an EL layer is sandwiched between a pair of electrodes. The EL layer usually has a stacked structure. Typically, a laminated structure of “hole transport layer / light-emitting layer / electron transport layer” is given. This structure has a very high luminous efficiency, and most light-emitting devices currently under research and development adopt this structure.
[0008]
A light-emitting element formed of a cathode, an EL layer, and an anode is referred to as an EL element. The light-emitting element includes a method in which an EL layer is formed between two types of stripe-shaped electrodes provided to be orthogonal to each other (simple matrix). System) or a system in which an EL layer is formed between a pixel electrode connected to a TFT and arranged in a matrix and an opposing electrode (active matrix system). However, when the pixel density increases, it is considered that the active matrix method in which a switch is provided for each pixel (or one dot) is advantageous because it can be driven at a low voltage.
[0009]
In an active matrix light emitting device, an electrode electrically connected to a TFT on a substrate is formed as an anode, an organic compound layer is formed on the anode, and a cathode is formed on the organic compound layer. It had a light emitting element, and the structure was such that light generated in the organic compound layer was extracted from the anode, which is a transparent electrode, toward the TFT.
[0010]
[Problems to be solved by the invention]
Therefore, in the present invention, a first electrode is formed as an anode, a layer containing an organic compound is formed over the anode, and a cathode including a second electrode which transmits light is formed over the layer containing an organic compound. An active matrix light-emitting device including a light-emitting element having a structure (hereinafter, referred to as a top emission structure) is manufactured. Alternatively, a light-emitting element having a structure in which a first electrode is formed as a cathode, a layer including an organic compound is formed over the cathode, and an anode including a second electrode which transmits light is formed over the layer including the organic compound. Is manufactured.
[0011]
Also, not all of the light generated in the layer containing the organic compound is extracted to the observer (user). For example, the light is also emitted in the lateral direction (the direction parallel to the substrate surface). In addition, since the light emitted in the lateral direction is not extracted, a loss occurs. Therefore, an object of the present invention is to provide a light-emitting device having a structure in which the amount of light emitted in one direction is increased in a light-emitting element and a manufacturing method thereof.
[0012]
Further, in a light-emitting element including an organic compound, a path from the time when electrons and holes injected from an electrode are converted into photons to finally extracted outside the element is considered. Only a certain percentage of the current flowing through the external circuit can contribute to carrier binding as electron-hole pairs, and a part of the recombined electron-hole pairs is consumed for generation of luminescent molecular excitons. The generated excitons are converted into photons by a ratio defined by the fluorescence quantum efficiency, and the rest are deactivated by various routes, for example, heat deactivation or infrared light emission. Therefore, when such a light-emitting element is driven to emit light, Joule heat is generated, and this heat causes decomposition and crystallization of the organic compound, resulting in deterioration of the light-emitting element.
[0013]
Therefore, another object of the present invention is to efficiently remove or reduce heat generation in a light-emitting element including an organic compound.
[0014]
[Means for Solving the Problems]
According to the present invention, an FET is formed using a semiconductor substrate, a first electrode including a metal layer which is an electrode (a drain electrode or a source electrode) of the FET is formed, and an end of the first electrode is formed. After forming a covering insulator (referred to as a bank or a partition), etching is performed in a self-aligned manner using the insulator as a mask, a part of the insulator is etched, and a central portion of the first electrode is thinly etched. To form a step at the end. By this etching, the central portion of the first electrode is made thin and flat, and the end portion of the first electrode covered with the insulator is made thick, that is, a concave shape. Then, a layer containing an organic compound and a second electrode are formed over the first electrode, whereby a light-emitting element is completed.
[0015]
The present invention increases or decreases the amount of light emitted in one direction (the direction passing through the second electrode) by reflecting or condensing light emitted in the horizontal direction on a slope formed at a step portion of the first electrode. It is.
[0016]
Therefore, the portion that becomes the slope is preferably made of a material that mainly reflects a metal that reflects light, for example, aluminum, silver, or the like. The central portion in contact with the layer containing an organic compound is an anode material having a large work function, or It is preferable to use a cathode material having a small work function.
[0017]
Further, in the present invention, since a semiconductor substrate having excellent heat dissipation properties is used, heat generation can be efficiently removed or reduced. In addition, the semiconductor substrate of the present invention has various circuits (an inverter circuit, a NAND circuit, an AND circuit, a NOR circuit, an OR circuit, a shift register circuit, a sampling circuit, Driving circuit having CMOS circuit such as / A converter circuit, A / D converter circuit, latch circuit, buffer circuit, correction circuit, CPU, memory element such as SRAM or DRAM, photoelectric conversion element having silicon PIN connection, thin film diode , Resistance elements, etc.) at the same time. In addition, a fine pattern can be formed, and these circuits can be three-dimensionally integrated. Therefore, the area occupied by a drive circuit including various circuits and elements can be reduced, and the area of the frame portion is reduced, so that the overall size can be made more compact.
[0018]
Further, the above-described configuration is a configuration in which the first electrode and the drain electrode of the FET are integrated in order to reduce the total number of masks and steps. Electrodes may be formed. Further, in order to increase the aperture ratio, two photomasks may be added to form a first electrode including a stacked metal layer connected to a drain electrode (or a source electrode) of an FET through an insulating film.
[0019]
Configuration 1 of the invention disclosed in this specification includes:
A first electrode connected to a field-effect transistor provided on a semiconductor substrate;
An insulator covering an end of the first electrode;
A light-emitting element including a layer containing an organic compound in contact with the first electrode and a second electrode in contact with the layer;
The first electrode has an inclined surface toward the center of the first electrode at an end of the first electrode, and the inclined surface reflects light emitted from the layer containing the organic compound. A semiconductor device characterized by the following.
[0020]
In addition, Configuration 2 of another invention is as follows.
A first electrode connected to a field-effect transistor provided on a semiconductor substrate;
An insulator covering an end of the first electrode;
A light-emitting element including a layer containing an organic compound in contact with the first electrode and a second electrode in contact with the layer;
A semiconductor device, wherein a central portion of the first electrode has a concave shape having a smaller thickness than an end portion.
[0021]
In addition, Configuration 3 of another invention is as follows.
A first electrode connected to a field-effect transistor provided on a semiconductor substrate;
An insulator covering an end of the first electrode;
A light-emitting element including a layer containing an organic compound in contact with the first electrode and a second electrode in contact with the layer;
The semiconductor device is characterized in that the first electrode has a multilayer structure, and the number of layers at the end portion is larger than that at the center of the first electrode.
[0022]
In addition, Configuration 4 of another invention is as follows.
A first electrode connected to the field effect transistor;
An insulator covering an end of the first electrode;
A light-emitting element including a layer containing an organic compound in contact with the first electrode and a second electrode in contact with the layer;
The first electrode has a depression (also referred to as a depression), the width of the bottom (the bottom in the cross section) of the depression is smaller than the width of the top (the top in the cross section) of the depression, and the slope of the depression is And a semiconductor device that reflects light emitted from the layer containing the organic compound.
[0023]
Further, according to the present invention, when an organic compound film made of a polymer is formed by a coating method, the shape of an insulator (referred to as a bank, a partition, a barrier, a bank, etc.) provided between pixels in order to eliminate poor coverage or the like. Add some ingenuity to In each of the above structures, the upper end of the insulator has a curved surface having a radius of curvature, and the radius of curvature is 0.2 μm to 3 μm. The insulator may have a taper angle of 35 ° to 55 °.
[0024]
By providing a curvature, the step coverage can be improved, and a film can be formed even if a layer containing an organic compound to be formed later is extremely thin.
[0025]
In each of the above-described configurations, the first electrode has an inclined surface facing a central portion of the first electrode, and an inclination angle (also referred to as a taper angle) exceeds 30 °, less than 70 °, and Preferably, it is less than 60 °. The angle of inclination, the material and thickness of the organic compound layer, or the material and thickness of the second electrode are appropriately adjusted so that the light reflected on the inclined surface of the first electrode is not dispersed between the layers or becomes stray light. It is necessary to set the film thickness.
[0026]
In each of the above structures, the second electrode is a conductive film that transmits light, for example, a thin metal film, a transparent conductive film, or a stacked film thereof.
[0027]
Further, in each of the above structures, the first electrode has a concave shape and is formed in a self-aligned manner using the insulator as a mask. Therefore, there is no increase in the number of masks in forming the first electrode shape. The step portion (upper end portion of the inclined portion) of the first electrode and the side surface of the insulator substantially coincide with each other, and from the viewpoint of step coverage, preferably, the inclination angle on the inclined surface of the first electrode is equal to the insulation. It is desirable that the inclination angle on the side surface of the object is the same.
[0028]
In each of the above structures, the first electrode is a part of a drain electrode or a source electrode of the field effect transistor. When a part of the drain electrode or the source electrode is used as the first electrode, they can be formed at the same time, and the number of masks and steps can be reduced. Alternatively, the first electrode and a drain electrode or a source electrode of the field-effect transistor may be formed separately in different steps. In that case, the first electrode may be a drain electrode or a field-effect transistor of the field-effect transistor. A material different from that of the source electrode can be used.
[0029]
Further, in each of the above structures, the first electrode is an anode, and the second electrode is a cathode. Alternatively, in each of the above structures, the first electrode is a cathode and the second electrode is an anode.
[0030]
In each of the above structures, the layer containing the organic compound is a material that emits white light, and a light-emitting device combined with a color filter provided in a sealing material, or the layer containing the organic compound is It is a material that emits monochromatic light, and is characterized by being combined with a color conversion layer or a coloring layer provided in a sealing material.
[0031]
Further, according to the present invention, after a step of the first electrode is formed, a wiring (also referred to as an auxiliary wiring or a third electrode) is formed over an insulator arranged between the pixel electrodes by a vapor deposition method using a vapor deposition mask. The film resistance of the electrode serving as the cathode (the electrode that transmits light) may be reduced. In addition, a feature of the present invention is that a lead wiring is formed using the auxiliary wiring and connected to another wiring existing in a lower layer.
[0032]
Further, in each of the above structures, the field effect transistor is a MISFET, a MOSFET, or a TFT.
[0033]
In each of the above structures, the semiconductor substrate is provided with a CPU, a memory element, a thin-film diode, a photoelectric conversion element, or a resistance element.
[0034]
The configuration of the invention for realizing each of the above configurations 1, 2, and 3 is as follows:
A method for manufacturing a semiconductor device including a light-emitting element having an anode, a layer containing an organic compound in contact with the anode, and a cathode in contact with the layer containing the organic compound,
Forming a field effect transistor on the semiconductor substrate;
Forming an insulator covering an end of a first electrode which is a part of a drain electrode or a source electrode of the field effect transistor;
Using the insulator as a mask, performing etching, and thinning a central portion of the first electrode so that a slope is exposed along an edge of the first electrode formed of a stacked metal layer;
Forming a film containing an organic compound in contact with a central portion and a slope of the first electrode;
Forming a second electrode made of a light-transmitting metal thin film on the film containing the organic compound.
[0035]
In the structure related to the above manufacturing method, the first electrode has a stack of a metal layer that reflects light and a metal layer that serves as an etching stopper, and the metal layer that reflects light is etched, and Is characterized in that a metal material that reflects light is exposed.
[0036]
Further, the surface of the metal layer serving as an etching stopper may be slightly etched by the etching of the first electrode.
[0037]
Further, in the above structure, the first electrode is an anode, and is formed of a metal layer having a larger work function than the second electrode.
[0038]
Further, in the above structure, the first electrode includes a first metal layer containing titanium, a second metal layer containing titanium nitride or tungsten nitride, a third metal layer containing aluminum, It is characterized by being stacked with a fourth metal layer containing titanium nitride.
[0039]
Note that the first metal layer is in contact with the source region or the drain region of the TFT; therefore, a metal material (typically, titanium) having good ohmic contact with silicon may be selected, and the second metal layer functioning as an anode can be used. As the metal layer, a material having a large work function is preferable. As the third metal layer for reflecting light of the light emitting element, a metal material having a high light reflectance is preferable. As the fourth metal layer, a third metal layer is used. It is preferable to use a metal material (titanium nitride or titanium) that prevents the generation of hillocks and whiskers, and also prevents specular reflection of the third metal layer.
[0040]
Further, the first electrode is not limited to the above four-layer structure, and is not particularly limited as long as it has at least two layers: a metal layer functioning as an anode and a metal layer having a slope for reflecting light of the light emitting element. Not done.
[0041]
FIG. 12 shows the reflectance of an aluminum film containing a small amount of Ti and the reflectance of a TiN film (100 nm). Titanium nitride is a material that can prevent specular reflection. In addition, when titanium nitride is used as the anode, it hardly reflects light, so that interference due to return light of the light emitting element does not occur. Therefore, a panel structure which does not need to provide a circularly polarizing plate can be obtained.
[0042]
For example, in the first electrode, titanium as the first metal layer, titanium nitride as the second metal layer, metal film containing aluminum as the third metal layer, titanium nitride as the fourth metal layer, fifth metal layer A six-layer structure of a metal film containing aluminum as the metal layer and titanium nitride as the sixth metal layer may be used. In the case of the six-layer structure, the fourth metal layer is used as an anode, the light from the light emitting element is reflected on the slope of the fifth metal layer, and a metal film containing aluminum is provided below the anode. Therefore, the resistance of the entire first electrode can be reduced.
[0043]
In the structure of the above manufacturing method, the work function of the metal layer serving as the anode may be increased by performing ultraviolet irradiation treatment (referred to as UV ozone treatment) in an ozone atmosphere. FIG. 13 shows the result of measuring the change in the work function with the UV ozone treatment time. As shown in FIG. 13, the work function of titanium nitride is 4.7 eV, but the work function can be made 5.05 eV by UV treatment (for 6 minutes). It is noted that the work function of tantalum nitride also tends to increase. In addition, in the configuration relating to the above manufacturing method, ₂ , O ₂ , Ar, BCl, Cl ₂ The work function of the metal layer serving as the anode may be increased by performing plasma treatment using one or more of these gases.
[0044]
Incidentally, in FIG. 13, the work function was measured in the atmosphere and measured by photoelectron spectroscopy using “Photoelectron Spectroscopy AC-2” manufactured by Riken Keiki Co., Ltd.
[0045]
In the case where plasma etching is used in the step of performing etching using the insulator as a mask and thinning a central portion of the first electrode so that a slope is exposed along an edge of the first electrode, an etching gas may be used. Can reduce the work function of the metal layer serving as the anode at the same time as reducing the thickness of the central portion.
[0046]
In the structure of the above manufacturing method, the insulator covering the end of the first electrode has a curved surface having a radius of curvature at an upper end, and the radius of curvature is 0.2 μm to 3 μm. It is characterized by.
[0047]
Further, in the above structure, the field-effect transistor is a MISFET, a MOSFET, or a TFT.
[0048]
Note that the EL element includes a layer containing an organic compound capable of obtaining luminescence (Electro Luminescence) generated by application of an electric field (hereinafter, referred to as an EL layer), an anode, and a cathode. The luminescence of an organic compound includes light emission (fluorescence) when returning from a singlet excited state to a ground state and light emission (phosphorescence) when returning to a ground state from a triplet excited state. A light-emitting device manufactured by a film formation method can be applied to a case where either light emission is used.
[0049]
A light-emitting element (EL element) including an EL layer has a structure in which an EL layer is sandwiched between a pair of electrodes. The EL layer usually has a stacked 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 a very high luminous efficiency, and most light-emitting devices currently under research and development adopt this structure.
[0050]
In addition, a hole injection layer / a hole transport layer / a light emitting layer / an electron transport layer, or a hole injection layer / a hole transport layer / a light emitting layer / an electron transport layer / an electron injection layer are stacked in this order on the anode. The structure is also good. The light emitting layer may be doped with a fluorescent dye or the like. Further, these layers may be formed entirely using a low molecular material, or may be formed entirely using a high molecular material. In this specification, all layers provided between a cathode and an anode are collectively referred to as an EL layer. Therefore, the hole injection layer, the hole transport layer, the light emitting layer, the electron transport layer, and the electron injection layer are all included in the EL layer.
[0051]
In the light emitting device of the present invention, a driving method for screen display is not particularly limited, and for example, a dot sequential driving method, a line sequential driving method, a plane sequential driving method, or the like may be used. Typically, a line-sequential driving method is used, and a time-division grayscale driving method or an area grayscale driving method may be used as appropriate. Further, the video signal input to the source line of the light emitting device may be an analog signal or a digital signal, and a drive circuit or the like may be appropriately designed in accordance with the video signal.
[0052]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described below.
[0053]
(Embodiment 1)
FIG. 1A is a cross-sectional view (a part of one pixel) of an active matrix light-emitting device. Here, a light-emitting element in which a layer containing an organic compound formed of a polymer material that emits white light is used as a light-emitting layer will be described as an example.
[0054]
In FIG. 1A, an FET (PMOSFET) provided on a semiconductor substrate 10 is an element for controlling a current flowing through an EL layer 20 that emits white light, and 13 and 14 are a source region or a drain region.
[0055]
As the semiconductor substrate 10, an N-type or P-type single crystal silicon substrate (a (100) substrate, a (110) substrate, a (111) substrate, or the like) or a high-purity semiconductor substrate can be used. Further, for example, an FET is formed after a wafer (circle) having a diameter of 200 mm to 300 mm is cut and processed into a square substrate. Alternatively, after forming the FET and the light-emitting element, a multi-panel cutting into a desired size may be performed. Further, as the semiconductor substrate 10, a GaAs substrate, an InP substrate, a GaN substrate for GaN-based epi, a SiC substrate, a sapphire substrate, a compound semiconductor substrate represented by ZnSe or the like may be used. Further, an SOI (Si on Insulator) substrate structure may be formed by a wafer bonding method or a SIMOX (separation by implanted oxygen) method.
[0056]
A field oxide film 11 is formed on a semiconductor substrate 10, and a gate insulating film 12 is provided below a gate electrode 15. Although the example in which the sidewall is formed on the side of the gate electrode 15 is shown, the invention is not particularly limited. The field oxide film 11 is formed by using a selective oxidation method (also called a LOCOS method) to isolate each element, thermally oxidizing a semiconductor substrate to form an oxide film (pad oxide film), and then forming a mask nitride film thereon. Is formed by a CVD method, patterning is performed, the silicon surface is exposed only in the opening, and thermal oxidation is performed to form a field oxide film in the opening.
[0057]
Instead of the LOCOS method, a trench isolation suitable for miniaturization with a design rule of 0.25 μm or less may be used. Trench isolation is a method of forming a groove (trench) in a silicon substrate and then back-filling the groove with an insulator such as an oxide film to perform element isolation.
[0058]
16a is an interlayer insulating film made of a silicon nitride film or a silicon nitride oxide film, and 16b is a photosensitive or non-photosensitive organic material (polyimide, acrylic, polyamide, polyimide amide, resist or benzo) formed by a coating method. Planarization insulating film made of cyclobutene) or planarization insulating film made of an inorganic material (including a coated silicon oxide film, PSG (phosphorus-added glass, BPSG (boron and phosphorus-added glass), or the like), or a laminate thereof) Although not shown here, one or more other FETs (NMOS or PMOS) are provided for each pixel, which is not shown here. It is necessary to provide a region (well) having conductivity different from that of the substrate, and the method is to form a P-well on an N-type substrate. Then, an N-channel transistor is formed on the P-well, a P-well transistor is formed on the N-type substrate, a N-well is formed on the P-type substrate, a P-channel transistor is formed on the N-well, and an N-type transistor is formed on the P-type substrate. An N-well method for forming a channel transistor; a twin-well method for forming an N-well and a P-well on an N-type or P-type substrate, forming a P-channel transistor on the N-well and an N-channel transistor on the P-well; Although the FET having one channel formation region is shown here, the invention is not particularly limited, and an FET having a plurality of channels may be used.
[0059]
Reference numerals 18a to 18d denote first electrodes, that is, anodes (or cathodes) of OLEDs, and reference numeral 21 denotes second electrodes made of a conductive film, that is, cathodes (or anodes) of OLEDs. Here, a titanium film 18a, a titanium nitride film 18b, an aluminum-based film 18c, and a titanium nitride film 18d are sequentially stacked, and the layer 18b in contact with the layer 20 containing an organic compound functions as an anode. Further, the power supply line 17 is formed in the same laminated structure. The stacked structure includes a film containing aluminum as a main component, can be a low-resistance wiring, and the source wiring 22 and the like are formed at the same time.
[0060]
In order to obtain white light emission, a poly (ethylenedioxythiophene) / poly (styrenesulfonic acid) aqueous solution (PEDOT / PSS) serving as a hole injection layer was applied and baked as the layer 20 containing an organic compound. Thereafter, a luminescent center dye (1,1,4,4-tetraphenyl-1,3-butadiene (TPB), 4-dicyanomethylene-2-methyl-6- (p-dimethylamino-styryl) acting as a luminescent layer -4H-pyran (DCM1), Nile Red, Coumarin 6, etc.)-Doped polyvinyl carbazole (PVK) solution is applied and baked on the entire surface. Note that PEDOT / PSS uses water as a solvent and does not dissolve in an organic solvent. Therefore, when PVK is applied from above, there is no need to worry about re-dissolving. Since PEDOT / PSS and PVK have different solvents, it is preferable not to use the same film forming chamber. Alternatively, the layer 20 containing an organic compound may be a single layer, and a 1,3,4-oxadiazole derivative (PBD) having an electron transporting property may be dispersed in polyvinyl carbazole (PVK) having a hole transporting property. . Further, white light emission can be obtained by dispersing 30 wt% of PBD as an electron transporting agent and dispersing an appropriate amount of four kinds of dyes (TPB, coumarin 6, DCM1, and Nile Red).
[0061]
Alternatively, a film containing an organic compound that emits red light, a film containing an organic compound that emits green light, or a film containing an organic compound that emits blue light can be appropriately selected, and white light emission can be obtained as a whole by overlapping and mixing colors. .
[0062]
Also, as 21 ₂ Is formed to a thickness of 1 nm to 10 nm by a vapor deposition method, and finally, an Al film is formed to a thickness of about 10 nm by a sputtering method or a vapor deposition method to function as a cathode. For the cathode, it is necessary to appropriately select a film thickness and a material through which light from the layer 20 containing an organic compound passes. Note that in this specification, the term “cathode” includes not only a single-layer film of a material film with a small work function but also a stacked film of a material thin film with a small work function and a conductive film.
[0063]
When an Al film is used as the second electrode 21, a material in contact with the layer 20 containing an organic compound can be formed using a material other than an oxide, so that the reliability of the light-emitting device can be improved. Instead of the Al film, a transparent conductive film (ITO (indium oxide tin oxide alloy), indium oxide zinc oxide alloy (Indium oxide)) is used as the second electrode 21. ₂ O ₃ -ZnO), zinc oxide (ZnO) or the like may be used. In addition, CaF ₂ Instead, a thin metal layer (typically, an alloy such as MgAg, MgIn, or AlLi) may be used.
[0064]
In addition, both ends of the first electrode 18 and the space between them are covered with an insulator 19 (also called a barrier or a bank). In the present invention, the cross-sectional shape of the insulator 19 is important. By the etching process for forming the insulator 19, the concave shape of the first electrode 18 is formed. If the upper end of the insulator 19 does not have a curved surface, a film formation defect in which a protrusion is formed at the upper end of the insulator 19 is likely to occur. Therefore, according to the present invention, a curved surface having a radius of curvature is formed at the upper end portion of the insulator 19, and a part of the first electrodes 18c and 18d is exposed in accordance with the curved surface to form a slope, thereby forming a light emitting region. Etching is performed so that the first electrode 18b is exposed in the region. Further, a treatment (such as a CMP treatment) for planarizing the surface of the exposed first electrode 18b may be performed. Further, the thickness of the first electrode 18b may be increased, and the first electrode 18b may be etched so that a part of the first electrode 18b also has a slope. Note that the radius of curvature is preferably set to 0.2 μm to 3 μm. According to the present invention, coverage of an organic compound film or a metal film can be improved. Further, the taper angle on the side surface of the insulator 19 and the taper angle on the inclined surfaces of the first electrodes 18c and 18d may be both 45 ° ± 10 °.
[0065]
Note that there is no particular limitation on the treatment for etching the concave shape of the first electrode, and dry etching, wet etching, or an etching method combining these may be employed. For example, using an ICP (Inductively Coupled Plasma) etching method, etching conditions (the amount of power applied to a coil-type electrode, the amount of power applied to a substrate-side electrode, the substrate-side electrode temperature, etc.) The film can be etched into a desired tapered shape by appropriately adjusting. The etching gas used is Cl. ₂ , BCl ₃ , SiCl ₄ , CCl ₄ Such as chlorine-based gas or CF ₄ , SF ₆ , NF ₃ Such as fluorine-based gas or O ₂ Can be used as appropriate. Here, 450 W of RF (13.56 MHz) power is applied to the coil-type electrode at a pressure of 1.9 Pa, and 100 W of RF (13.56 MHz) power is also applied to the substrate side (sample stage). , A negative self-bias voltage is applied. The electrode area size on the substrate side is 12.5 cm × 12.5 cm, and the coil-type electrode area size (here, a quartz disk provided with a coil) is a disk having a diameter of 25 cm. BCl for etching gas ₃ And Cl ₂ The shape of the first electrode and the insulator can be formed with the respective gas flow ratios of 60/20 (sccm).
[0066]
Further, a three-layer structure may be adopted. For example, a titanium film 18a, a titanium nitride film 18b, and a film mainly containing aluminum as 18c may be sequentially stacked.
[0067]
In the present invention, light emitted from the organic compound layer 20 is reflected by the slopes of the first electrodes 18c and 18d to increase the total light extraction amount in the direction of the arrow shown in FIG. And
[0068]
As shown in FIG. 1B, an auxiliary electrode 23 may be provided on the conductive film 21 in order to reduce the resistance of the conductive film (cathode) 21. The auxiliary electrode 23 may be selectively formed by an evaporation method using an evaporation mask.
[0069]
Although not illustrated, a protective film is preferably formed over the second electrode 21 in order to increase the reliability of the light emitting device. This protective film is an insulating film mainly containing silicon nitride or silicon nitride oxide obtained by a sputtering method (DC method or RF method), or a thin film mainly containing carbon. When a silicon target is formed in an atmosphere containing nitrogen and argon, a silicon nitride film can be obtained. Further, a silicon nitride target may be used. Further, the protective film may be formed using a film forming apparatus using remote plasma. In addition, in order to allow light to pass through the protective film, the thickness of the protective film is preferably as small as possible.
[0070]
In the present invention, the thin film containing carbon as a main component is a DLC film (Diamond like Carbon) having a thickness of 3 to 50 nm. The DLC film has a short-range order as a bond between carbons, SP ³ Although it has a bond, it has an amorphous structure macroscopically. The DLC film has a composition of 70 to 95 atomic% of carbon and 5 to 30 atomic% of hydrogen, and is very hard and excellent in insulating properties. Further, such a DLC film has a feature that the gas permeability of water vapor, oxygen, and the like is low. Moreover, it is known that it has a hardness of 15 to 25 GPa as measured by a micro hardness tester.
[0071]
The DLC film can be formed by a plasma CVD method (typically, an RF plasma CVD method, a microwave CVD method, an electron cyclotron resonance (ECR) CVD method, or the like), a sputtering method, or the like. With any of the film forming methods, a DLC film can be formed with good adhesion. The DLC film is formed by placing the substrate on the cathode. Alternatively, a dense and hard film can be formed by applying a negative bias and utilizing ion bombardment to some extent.
[0072]
The reaction gas used for the film formation is a hydrogen gas and a hydrocarbon-based gas (eg, CH 2 ₄ , C ₂ H ₂ , C ₆ H ₆ And ionization is performed by glow discharge, and ions are accelerated and collided with a negatively biased cathode to form a film. By doing so, a dense and smooth DLC film can be obtained. The DLC film is an insulating film that is transparent or translucent to visible light.
[0073]
In the present specification, “transparent to visible light” means that the transmittance of visible light is 80 to 100%, and “translucent to visible light” means that the transmittance of visible light is 50 to 80%. Refers to
[0074]
In addition, although a top gate type TFT has been described as an example here, the present invention can be applied regardless of the TFT structure. For example, the present invention can be applied to a bottom gate type (reverse stagger type) TFT and a forward stagger type TFT. Is possible.
[0075]
(Embodiment 2)
Hereinafter, a method in which a white light-emitting element and a color filter are combined (hereinafter, referred to as a color filter method) will be described with reference to FIG.
[0076]
The color filter method is a method in which a light-emitting element having an organic compound film which emits white light is formed, and red, green, and blue lights are obtained by passing the obtained white light through a color filter.
[0077]
There are various methods for obtaining white light emission. Here, the case of using a light emitting layer made of a polymer material that can be formed by coating will be described. In this case, the doping of the polymer material to be the light emitting layer with the dye can be performed by adjusting the solution, and can be obtained extremely easily as compared with a vapor deposition method in which a plurality of dyes are co-deposited.
[0078]
Specifically, a poly (ethylenedioxythiophene) / poly (styrenesulfone) acting as a hole injection layer is formed on an anode made of a metal (Pt, Cr, W, Ni, Zn, Sn, In) having a large work function. Acid) aqueous solution (PEDOT / PSS) is applied to the entire surface and baked, and then the luminescent center dye (1,1,4,4-tetraphenyl-1,3-butadiene (TPB), 4-dicyanomethylene, which acts as a luminescent layer) After coating and calcining a polyvinyl carbazole (PVK) solution doped with -2-methyl-6- (p-dimethylamino-styryl) -4H-pyran (DCM1), Nile Red, coumarin 6, etc. A thin film containing small metals (Li, Mg, Cs) and a transparent conductive film (ITO (indium oxide tin oxide alloy), indium oxide oxidation) Lead alloy (In ₂ O ₃ (ZnO), zinc oxide (ZnO), etc.). Note that PEDOT / PSS uses water as a solvent and does not dissolve in an organic solvent. Therefore, when PVK is applied from above, there is no need to worry about re-dissolving. Since PEDOT / PSS and PVK have different solvents, it is preferable not to use the same film forming chamber.
[0079]
Further, in the above example, an example in which the organic compound layers are stacked is described, but the organic compound layer may be a single layer. For example, a 1,3,4-oxadiazole derivative (PBD) having an electron transporting property may be dispersed in polyvinyl carbazole (PVK) having a hole transporting property. Further, white light emission can be obtained by dispersing 30 wt% of PBD as an electron transporting agent and dispersing an appropriate amount of four kinds of dyes (TPB, coumarin 6, DCM1, and Nile Red).
[0080]
Note that the organic compound film is formed between the anode and the cathode, and the holes injected from the anode and the electrons injected from the cathode recombine in the organic compound film, so that the organic compound film emits white light. Is obtained.
[0081]
Alternatively, white light emission can be obtained as a whole by appropriately selecting an organic compound film emitting red light, an organic compound film emitting green light, and an organic compound film emitting blue light and overlapping and mixing colors.
[0082]
The organic compound film formed as described above can obtain white light emission as a whole.
[0083]
A color provided with a colored layer (R) that absorbs light other than red light emission, a colored layer (G) that absorbs light other than green light, and a colored layer (B) that absorbs light other than blue light in the direction in which the organic compound film emits white light. By forming the filter, white light emission from the light-emitting element can be separated into red light emission, green light emission, and blue light emission. In the case of an active matrix type, a structure is employed in which a TFT is formed between a substrate and a color filter.
[0084]
For the colored layers (R, G, B), a diagonal mosaic arrangement, a triangular mosaic arrangement, an RGBG four-pixel arrangement, an RGBW four-pixel arrangement, or the like can be used, including the simplest stripe pattern.
[0085]
The coloring layer constituting the color filter is formed using a color resist made of an organic photosensitive material in which a pigment is dispersed. The chromaticity coordinates of white light emission are (x, y) = (0.34, 0.35). By combining white light emission and a color filter, color reproducibility as a full color can be sufficiently ensured.
[0086]
Note that, in this case, even if the obtained luminescent colors are different, it is not necessary to separately form the organic compound film for each luminescent color because all of the luminescent colors are formed of organic compound films which emit white light. In addition, a circularly polarizing plate for preventing specular reflection may not be particularly required.
[0087]
Next, a CCM method (color changing media) realized by combining a blue light emitting element having a blue light emitting organic compound film and a fluorescent color conversion layer will be described with reference to FIG.
[0088]
The CCM method excites a fluorescent color conversion layer with blue light emitted from a blue light emitting element, and performs color conversion in each color conversion layer. More specifically, the color conversion layer converts blue to red (B → R), the color conversion layer converts blue to green (B → G), and the color conversion layer converts blue to blue (B → B). ) (The conversion from blue to blue need not be performed) to obtain red, green, and blue light emission. Also in the case of the CCM method, in the case of the active matrix type, a TFT is formed between the substrate and the color conversion layer.
[0089]
In this case, it is not necessary to separately form the organic compound film. In addition, a circularly polarizing plate for preventing specular reflection may not be particularly required.
[0090]
Further, when the CCM method is used, since the color conversion layer is fluorescent, it is excited by external light, and there is a problem that the contrast is reduced. Therefore, a color filter is attached as shown in FIG. And increase the contrast.
[0091]
This embodiment can be combined with Embodiment 1.
[0092]
(Embodiment 3)
Here, FIG. 4 shows an example in which a base insulating film is formed over a semiconductor substrate and a TFT, which is a kind of FET, is formed thereon.
[0093]
As the semiconductor substrate 40, an N-type or P-type single crystal silicon substrate (a (100) substrate, a (110) substrate, a (111) substrate, or the like) or a high-purity semiconductor substrate can be used. Further, for example, an FET is formed after a wafer (circle) having a diameter of 200 mm to 300 mm is cut and processed into a square substrate. Alternatively, after forming the FET and the light-emitting element, a multi-panel cutting into a desired size may be performed. Further, as the semiconductor substrate 40, a GaAs substrate, an InP substrate, a GaN substrate for GaN-based epi, a SiC substrate, a sapphire substrate, or a compound semiconductor substrate represented by ZnSe may be used. Further, an SOI (Si on Insulator) substrate structure may be formed by a wafer bonding method or a SIMOX (separation by implanted oxygen) method. The semiconductor substrate 40 is for dispersing heat generated by the light emitting element.
[0094]
First, a base insulating film 41 is formed on a semiconductor substrate 40.
[0095]
The base insulating film 41 is made of SiH ₄ , NH ₃ , And N ₂ A silicon oxynitride film is formed to a thickness of 10 to 200 nm (preferably 50 to 100 nm) using O as a reaction gas. Here, a 50-nm-thick silicon oxynitride film (composition ratio: Si = 32%, O = 27%, N = 24%, H = 17%) is formed. Next, as the second layer of the base insulating film, SiH ₄ And N ₂ A silicon oxynitride film is formed to a thickness of 50 to 200 nm (preferably 100 to 150 nm) using O as a reaction gas. Here, a 100-nm-thick silicon oxynitride film (composition ratio: Si = 32%, O = 59%, N = 7%, H = 2%) is formed. Although a two-layer structure is used as the base insulating film 41 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.
[0096]
Next, a semiconductor layer is formed over the base film. As a semiconductor layer to be an active layer of a TFT, a semiconductor film having an amorphous structure is formed by a known means (a sputtering method, an LPCVD method, a plasma CVD method, or the like) and then a known crystallization treatment (laser crystallization). , A thermal crystallization method, a thermal crystallization method using a catalyst such as nickel, or the like) to form a crystalline semiconductor film obtained by patterning into a desired shape. This semiconductor layer is formed to have a thickness of 25 to 80 nm (preferably 30 to 60 nm). The material of the crystalline semiconductor film is not limited, but is preferably formed using silicon or a silicon-germanium alloy.
[0097]
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, a YVO laser, or the like is used. ₄ Lasers can be used. In the case of using these lasers, a method in which laser light emitted from a laser oscillator is linearly condensed by an optical system and irradiated to a semiconductor film is preferably used. The crystallization conditions are appropriately selected by the practitioner. When an excimer laser is used, the pulse oscillation frequency is 30 Hz, and the laser energy density is 100 to 400 mJ / cm. ² (Typically 200 to 300 mJ / cm ² ). When a YAG laser is used, its second harmonic is used, the pulse oscillation frequency is set to 1 to 10 kHz, and the laser energy density is set to 300 to 600 mJ / cm. ² (Typically 350-500 mJ / cm ² ). Then, a laser beam condensed linearly with a width of 100 to 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 set to 80 to 98%. Good.
[0098]
Next, the surface of the semiconductor layer is washed with an etchant containing hydrofluoric acid to form a gate insulating film covering the semiconductor layer. The gate insulating film is formed using a plasma CVD method or a sputtering method with a thickness of 40 to 150 nm and containing silicon. In this embodiment, a silicon oxynitride film (composition ratio: Si = 32%, O = 59%, N = 7%, H = 2%) is formed with a thickness of 115 nm by a plasma CVD method. 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.
[0099]
Next, after cleaning the surface of the gate insulating film, the gate electrode 45 is formed. Next, the gate insulating film is etched using the gate electrode as a mask to form the gate insulating film 42.
[0100]
Next, a source region 43 and a drain region 44 are formed by appropriately adding an impurity element (B or the like) which imparts p-type to the semiconductor, here, boron. After the addition, heat treatment, intense light irradiation, or laser light irradiation is performed to activate the impurity elements. In addition, simultaneously with the activation, plasma damage to the gate insulating film 42 and plasma damage to the interface between the gate insulating film 42 and the semiconductor layer can be recovered.
[0101]
In the subsequent steps, an interlayer insulating film 46a made of a silicon nitride film and a silicon nitride oxide film is formed by a PCVD method, and a photosensitive or non-photosensitive organic material (polyimide, acrylic, polyamide, polyimide amide) formed by a coating method is formed. , A planarizing insulating film made of resist or benzocyclobutene), or a planarizing insulating film made of an inorganic material (including a coated silicon oxide film, PSG (phosphorus-added glass, BPSG (boron and phosphorus-added glass), etc.)), Alternatively, an interlayer insulating film 46b is formed using these stacked films, and after hydrogenation, a contact hole reaching a source region or a drain region is formed. (Wiring) 52, an insulator 49, a power supply line 47, and first electrodes (drain electrodes) 48a to 48d to form a TFT To complete the p-channel type TFT).
[0102]
Subsequent steps are the same as those in Embodiment 1, and a layer 50 containing an organic compound and a second electrode 51 formed of a conductive film may be formed in accordance with Embodiment 1.
[0103]
This embodiment can be freely combined with Embodiment 1 or 2.
[0104]
The present invention having the above configuration will be described in more detail with reference to the following embodiments.
[0105]
(Example)
[Example 1]
Embodiment 1 In this embodiment, an example of a procedure for forming a light-emitting element of the present invention will be briefly described below with reference to FIGS.
[0106]
First, a MOSFET is formed on the semiconductor substrate 30 using a known technique. According to a known technique, element isolation is performed using the field oxide film 31 and doping processing is performed to form the drain region 32 or the source region. In addition, channel doping in which a trace amount of an element imparting n-type or p-type is added to a portion to be a channel formation region of the MOSFET.
[0107]
An interlayer insulating film 33 made of a silicon nitride film or a silicon nitride oxide film is formed by a PCVD method, and a photosensitive or non-photosensitive organic material (polyimide, acrylic, polyamide, polyimide amide, resist or A planarizing insulating film made of benzocyclobutene) or a planarizing insulating film made of an inorganic material (including a coated silicon oxide film, PSG (phosphorus-doped glass, BPSG (boron and phosphorous-doped glass), or the like), or the like) The interlayer insulating film 35 is formed using the laminated film.
[0108]
After the hydrogenation, a contact hole reaching the source region or the drain region is formed. Next, a source electrode (wiring) and a first electrode (drain electrode) are formed to complete an FET (p-channel FET).
[0109]
Through the above steps, the MOSFET (only the drain region 32 is shown here), the interlayer insulating films 33 and 35, and the first electrodes 36a to 36d are formed. (FIG. 3 (A))
[0110]
In the present embodiment, the first electrodes 36a to 36d are made of Ti, TiN, TiSi _X N _Y , Al, Ag, Ni, W, WSi _X , WN _X , WSi _X N _Y , Ta, TaN _X , TaSi _X N _Y , NbN, MoN, Cr, Pt, Zn, Sn, In, or Mo, or a film mainly composed of an alloy material or a compound material mainly composed of the above-mentioned elements, or a laminated film of them. The thickness may be in the range of 100 nm to 1 μm.
[0111]
In particular, the first electrode 36a in contact with the drain region 32 is preferably made of a material capable of forming ohmic contact with silicon, typically titanium, and has a thickness of 10 to 100 nm. The first electrode 36b is preferably made of a material having a large work function (TiN, TaN, MoN, Pt, Cr, W, Ni, Zn, Sn) when formed as a thin film, and has a thickness of 10 to 500 nm. Just fine. The first electrode 36c is preferably made of a metal material that reflects light, typically a metal material mainly containing Al or Ag, and has a thickness of 100 to 600 nm. Note that the first electrode 36b also functions as a blocking layer that prevents alloying of the first electrode 36c and the first electrode 36a. The first electrode 36d is preferably made of a material that prevents oxidation, corrosion, or hillocks of the first electrode 36c, typically a metal nitride (TiN, WN, or the like). The range may be set to 100 nm. Note that the first electrode 36d may not be provided.
[0112]
The first electrodes 36a to 36d can be formed simultaneously with another wiring, for example, the source wiring 34, a power supply line, and the like.
[0113]
Next, an insulator (referred to as a bank, a partition, a barrier, a bank, or the like) covering an end portion of the first electrode (and a contact portion with the drain region 32) is formed. (FIG. 3B) As an insulator, an inorganic material (eg, silicon oxide, silicon nitride, or silicon oxynitride), a photosensitive or non-photosensitive organic material (eg, polyimide, acrylic, polyamide, polyimide amide, resist, or benzocyclo) is used. Butene) or a laminate thereof can be used. In this embodiment, a photosensitive organic resin is used. For example, when a positive photosensitive acrylic is used as a material of the insulator, it is preferable that only the upper end portion of the insulator have a curved surface having a radius of curvature. Further, as the insulator, either a negative type which becomes insoluble in an etchant by photosensitive light or a positive type which becomes soluble in an etchant by light can be used.
[0114]
Next, the first electrodes 36c and 36d are partially removed while etching the insulator as shown in FIG. It is important to perform etching so that an inclined surface is formed on the exposed surface of the first electrode 36c and the exposed surface of the first electrode 36b is flat. This etching may be performed once or divided into a plurality of times by dry etching or wet etching, and a condition having a high selectivity between the first electrode 36b and the first electrode 36c is selected. The final radius of curvature of the upper end of the insulator is preferably 0.2 μm to 3 μm. In addition, the angle (tilt angle, taper angle) of the inclined surface toward the center of the first electrode is more than 30 ° and less than 70 °, and reflects light emitted from a layer containing an organic compound to be formed later. Let it.
[0115]
Next, a layer 38 containing an organic compound is formed by an evaporation method or a coating method. For example, when using a vapor deposition method, the degree of vacuum is 5 × 10 ^-3 Torr (0.665 Pa) or less, preferably 10 ^-4 -10 ^-6 Vapor deposition is performed in a film formation chamber evacuated to Pa. At the time of vapor deposition, the organic compound is vaporized by resistance heating in advance, and scatters in the direction of the substrate by opening a shutter during vapor deposition. The vaporized organic compound scatters upward and is deposited on the substrate through an opening provided in the metal mask. By stacking by evaporation, a layer containing an organic compound exhibiting white color is formed as the whole light-emitting element.
[0116]
For example, Alq ₃ , Alq partially doped with a red light-emitting dye Nile Red ₃ , Alq ₃ , P-EtTAZ, and TPD (aromatic diamine) are sequentially laminated to obtain white.
[0117]
In the case where a layer containing an organic compound is formed by a coating method using spin coating, it is preferable to perform baking by vacuum heating after coating. For example, a poly (ethylenedioxythiophene) / poly (styrenesulfonic acid) aqueous solution (PEDOT / PSS) acting as a hole injection layer is applied and baked over the entire surface, and then the luminescent center dye (1, 1) acting as a light emitting layer 1,4,4-tetraphenyl-1,3-butadiene (TPB), 4-dicyanomethylene-2-methyl-6- (p-dimethylamino-styryl) -4H-pyran (DCM1), Nile red, coumarin 6 Etc.) A doped polyvinyl carbazole (PVK) solution may be applied to the entire surface and fired.
[0118]
Further, in the above example, an example in which the organic compound layers are stacked is described, but the organic compound layer may be a single layer. For example, a 1,3,4-oxadiazole derivative (PBD) having an electron transporting property may be dispersed in polyvinyl carbazole (PVK) having a hole transporting property. Further, white light emission can be obtained by dispersing 30 wt% of PBD as an electron transporting agent and dispersing an appropriate amount of four kinds of dyes (TPB, coumarin 6, DCM1, and Nile Red). Further, a layer made of a high molecular material and a layer made of a low molecular material may be stacked as the organic compound layer. Further, the organic compound layer may contain an inorganic material such as silicon.
[0119]
Next, a metal having a small work function (MgAg, MgIn, AlLi, CaF ₂ , A thin film containing an alloy such as CaN or a film formed by co-evaporation of aluminum with an element belonging to Group 1 or 2 of the periodic table and a thin conductive film (aluminum film in this case) 39 thereon. Vapor deposition and lamination. (FIG. 2B) The aluminum film is a film having a high ability to block moisture and oxygen, and is a preferable material for the conductive film 39 in order to improve the reliability of the light-emitting device. Note that FIG. 2B shows a cross section taken along a chain line AA ′ in FIG. This laminated film has a thickness small enough to transmit light, and in this embodiment, functions as a cathode. In place of the thin conductive film, a transparent conductive film (ITO (indium tin oxide oxide), indium oxide zinc oxide alloy (In ₂ O ₃ -ZnO), zinc oxide (ZnO) or the like may be used. Further, an auxiliary electrode may be provided on the conductive film 39 in order to reduce the resistance of the cathode. The cathode may be formed selectively by using a resistance heating method by evaporation and by using an evaporation mask.
[0120]
The light-emitting element thus obtained emits white light in the direction of the arrow in FIG. 2B and reflects light emitted in the horizontal direction on the inclined surface of the first electrode 36c to increase the amount of light emitted in the direction of the arrow. . Note that a dotted line in FIG. 2A indicates a region where a field oxide film for element isolation or a gate wiring is formed.
[0121]
After the steps up to the formation of the second electrode (conductive film 39), a sealing substrate (transparent substrate) is attached with a sealant to seal the light-emitting element formed over the substrate 30. Note that a spacer made of a resin film may be provided in order to secure an interval between the sealing substrate and the light emitting element. The space inside the sealant is filled with an inert gas such as nitrogen. Note that an epoxy resin is preferably used as the sealant. Further, it is desirable that the sealant is a material that does not transmit moisture and oxygen as much as possible. Further, a substance (eg, a desiccant) having an effect of absorbing oxygen and water may be contained in the space.
[0122]
By enclosing the light-emitting element in the space as described above, the light-emitting element can be completely shut off from the outside, and a substance which promotes the deterioration of the organic compound layer such as moisture or oxygen from entering from the outside can be prevented. it can. Therefore, a highly reliable light-emitting device can be obtained.
[0123]
[Example 2]
In this embodiment, an example of forming an auxiliary electrode will be described below with reference to FIGS.
[0124]
FIG. 6A is a top view of a pixel, and FIG. 6B is a cross-sectional view taken along a chain line AA ′.
[0125]
In the present embodiment, the steps up to the formation of the insulator 67 are the same as those of the first embodiment, and thus are omitted here. The insulator 37 in FIG. 2B corresponds to the insulator 67 in FIG.
[0126]
According to the first embodiment, a field oxide film, a drain region 62, interlayer insulating films 63 and 65, first electrodes 66a to 66d, and an insulator 67 are formed on a substrate having an insulating surface.
[0127]
Next, a layer 68 containing an organic compound is selectively formed. In this embodiment, the layer 68 containing an organic compound is selectively formed by an evaporation method using an evaporation mask, an inkjet method, or the like.
[0128]
Next, the auxiliary electrode 60 is selectively formed over the insulator 67 by an evaporation method using an evaporation mask. The thickness of the auxiliary electrode 60 may be set in the range of 0.2 μm to 0.5 μm. In the present embodiment, an example is shown in which the auxiliary electrode 60 is arranged in the Y direction as shown in FIG. 6A, but is not particularly limited, and the auxiliary electrode 70 may be arranged in the X direction as shown in FIG. Good. Note that a cross-sectional view taken along a chain line AA ′ shown in FIG. 7 is the same as FIG. 2B.
[0129]
Next, as in the first embodiment, a metal having a small work function (MgAg, MgIn, AlLi, CaF ₂ , A thin film containing an alloy such as CaN or a film formed by co-evaporation of aluminum with an element belonging to Group 1 or 2 of the periodic table and a thin conductive film (here, an aluminum film) 69 thereon. Vapor deposition and lamination. This laminated film has a thickness small enough to transmit light, and in this embodiment, functions as a cathode. In place of the thin conductive film, a transparent conductive film (ITO (indium tin oxide oxide), indium oxide zinc oxide alloy (In ₂ O ₃ -ZnO), zinc oxide (ZnO) or the like may be used. In this embodiment, the auxiliary electrode 60 is provided on the insulator 67 so as to be in contact with the conductive film 69 in order to reduce the resistance of the cathode.
[0130]
The light-emitting element thus obtained emits white light in the direction of the arrow in FIG. 6B, and can reflect light in the horizontal direction on the inclined surface of the first electrode 66c to increase the amount of light in the direction of the arrow. .
[0131]
In addition, in this embodiment, since the resistance of the cathode is reduced by forming the auxiliary electrodes 60 and 70, the present embodiment can be applied to a pixel having a large size.
[0132]
In this embodiment, the example in which the auxiliary electrode 60 is formed after forming the layer 68 containing an organic compound is described. However, the formation order is not particularly limited. A layer may be formed.
[0133]
This embodiment can be freely combined with any one of Embodiment Modes 1 to 3 and Embodiment 1.
[0134]
[Example 3]
In this embodiment, an external view of the entire active matrix light emitting device will be described with reference to FIG. Note that FIG. 9A is a top view illustrating the light-emitting device, and FIG. 9B is a cross-sectional view of FIG. 9A taken along AA ′. Reference numeral 901 shown by a dotted line denotes a source signal line driving circuit, 902 denotes a pixel portion, and 903 denotes a gate signal line driving circuit. Reference numeral 904 denotes a sealing substrate, 905 denotes a sealant, and an inside surrounded by the sealant 905 is a space 907. IC chips 930a and 930b are mounted on the semiconductor substrate 910 by a COG (chip on glass) method, a wire bonding method, or a TAB (tape automated bonding) method.
[0135]
FIG. 9A illustrates a diagram in which an IC chip including a memory, a CPU, a D / A converter, and the like is mounted; however, since the present invention uses a semiconductor substrate as a substrate, a complicated It is possible to form an integrated circuit (memory, CPU, D / A converter, and the like). FIG. 8 is a system block diagram of a semiconductor device showing a form of a portable information terminal such as a PDA in which various circuits are formed on a semiconductor substrate.
[0136]
The configuration of the circuit mounted on the semiconductor device of FIG. 8 includes a power supply circuit including a stabilized power supply and a high-speed and high-precision operational amplifier, a controller, a memory, a correction circuit, and the like. Further, a CPU can be manufactured over the same substrate, and information processed by the CPU is output as a video signal (data signal) from the video signal processing circuit to the controller. The controller has a function of converting the video signal and the clock into respective timing specifications of the data signal side drive circuit and the gate signal side drive circuit.
[0137]
Specifically, a function of distributing a video signal to data corresponding to each pixel of a display device, and a method of converting a horizontal synchronization signal and a vertical synchronization signal input from the outside into a start signal of a driving circuit and a timing of AC conversion of a built-in power supply circuit. It has the function of converting to control signals.
[0138]
It is desired that a portable information terminal such as a PDA can be used for a long time outdoors or in a train by using a rechargeable battery as a power source without being connected to an AC outlet. In addition, such electronic devices are required to be lightweight and compact at the same time with an emphasis on portability. Batteries, which account for the majority of the weight of electronic devices, increase in weight as capacity increases. Therefore, in order to reduce the power consumption of such an electronic device, it is necessary to take measures from the software side, such as controlling the lighting time of the backlight and setting a standby mode.
[0139]
For example, when an input signal is not input to the CPU, the CPU enters a standby mode, in which some operations are stopped in synchronization. In the pixel portion, the emission intensity of the EL element is attenuated or the display of the image itself is stopped. Alternatively, in the semiconductor substrate, a memory element is formed in each pixel, and a measure such as switching to a still image display mode is taken. Thus, the power consumption of the electronic device can be reduced.
[0140]
In addition, to display a still image, the functions of the CPU, such as the video signal processing circuit and the VRAM, are stopped to reduce power consumption.
[0141]
Note that reference numeral 908 denotes wiring for transmitting signals input to the source signal line driver circuit 901 and the gate signal line driver circuit 903. receive. Although only the FPC is shown here, a printed wiring board (PWB) may be attached to the FPC. The light-emitting device in this specification includes not only the light-emitting device body but also a state in which an FPC or a PWB is attached thereto.
[0142]
Next, a cross-sectional structure is described with reference to FIG. A driver circuit and a pixel portion are formed over the semiconductor substrate 910; here, a source signal line driver circuit 901 and a pixel portion 902 are illustrated as the driver circuits.
[0143]
Note that as the source signal line driver circuit 901, a CMOS circuit in which an n-channel FET 923 and a p-channel FET 924 are combined is formed. Further, the TFT forming the driving circuit may be formed by a known CMOS circuit, PMOS circuit, or NMOS circuit. Further, in this embodiment, a driver integrated type in which a drive circuit is formed on a substrate is shown; however, this is not always necessary, and the driver circuit can be formed outside instead of on the substrate.
[0144]
Further, the pixel portion 902 is formed by a plurality of pixels including a switching FET 911, a current control FET 912, and a first electrode (anode) 913 electrically connected to a drain thereof.
[0145]
Insulators 914 are formed at both ends of the first electrode (anode) 913, and a part of the first electrode has a slope along a side surface of the insulator 914. The slope of the first electrode is formed at the same time when the insulating layer 914 is formed. The light emitted from the layer 915 containing the organic compound is reflected on this slope, so that the amount of light emitted in the light emitting direction indicated by the arrow in FIG. 9 is increased.
[0146]
Further, a layer 915 containing an organic compound is selectively formed over the first electrode (anode) 913. Further, a second electrode (cathode) 916 is formed over the layer 915 containing an organic compound. Thus, a light-emitting element 918 including the first electrode (anode) 913, the layer 915 containing an organic compound, and the second electrode (cathode) 916 is formed. Here, since the light-emitting element 918 emits white light, a color filter including a colored layer 931 and a BM 932 (an overcoat layer is not illustrated here for simplicity) is provided.
[0147]
Further, a third electrode (auxiliary electrode) 917, which is a part of the structure described in Embodiment 2, is formed over the insulating layer 914, and the resistance of the second electrode is reduced. Further, the second electrode (cathode) 916 also functions as a wiring common to all pixels, and is electrically connected to the FPC 909 via the third electrode 917 and the connection wiring 908.
[0148]
In addition, a sealing substrate 904 is attached with a sealant 905 to seal the light-emitting element 918 formed over the semiconductor substrate 910. Note that a spacer formed of a resin film may be provided in order to secure an interval between the sealing substrate 904 and the light-emitting element 918. The space 907 inside the sealant 905 is filled with an inert gas such as nitrogen. Note that an epoxy resin is preferably used as the sealant 905. Further, it is desirable that the sealant 905 is a material that does not transmit moisture or oxygen as much as possible. Further, a substance having an effect of absorbing oxygen or water may be contained in the space 907.
[0149]
In this embodiment, a plastic substrate made of FRP (Fiberglass-Reinforced Plastics), PVF (polyvinyl fluoride), mylar, polyester, acrylic, or the like is used as a material of the sealing substrate 904 in addition to a glass substrate or a quartz substrate. be able to. Further, after the sealing substrate 904 is bonded with the sealing agent 905, the sealing substrate 904 can be sealed with a sealing agent so as to further cover the side surface (exposed surface).
[0150]
By enclosing the light-emitting element in the space 907 as described above, the light-emitting element can be completely shut off from the outside and a substance such as moisture or oxygen which promotes the deterioration of the organic compound layer can be prevented from entering from the outside. Can be. Therefore, a highly reliable light-emitting device can be obtained.
[0151]
This embodiment can be freely combined with Embodiment Modes 1 to 3, Embodiment 1, and Embodiment 2.
[0152]
[Example 4]
By implementing the present invention, all electronic devices incorporating a module having an OLED (active matrix EL module) are completed.
[0153]
Examples of such electronic devices include a video camera, a digital camera, a head-mounted display (goggle-type display), a car navigation, a car stereo, a personal computer, a portable information terminal (a mobile computer, a mobile phone, an electronic book, or the like). . Examples of these are shown in FIGS.
[0154]
FIG. 10A illustrates a personal computer, which includes a main body 2001, an image input unit 2002, a display unit 2003, a keyboard 2004, and the like. However, since the present invention uses a semiconductor substrate (for example, a wafer diameter of 300 mm), the screen size is small or medium.
[0155]
FIG. 10B illustrates a video camera, which includes a main body 2101, a display portion 2102, an audio input portion 2103, operation switches 2104, a battery 2105, an image receiving portion 2106, and the like.
[0156]
FIG. 10C illustrates a mobile computer (mobile computer), which includes a main body 2201, a camera unit 2202, an image receiving unit 2203, operation switches 2204, a display unit 2205, and the like.
[0157]
FIG. 10D illustrates a goggle-type display, which includes a main body 2301, a display portion 2302, an arm portion 2303, and the like.
[0158]
FIG. 10E illustrates a player using a recording medium on which a program is recorded (hereinafter, referred to as a recording medium), and includes a main body 2401, a display portion 2402, a speaker portion 2403, a recording medium 2404, operation switches 2405, and the like. This player uses a DVD (Digital Versatile Disc), a CD, or the like as a recording medium, and can perform music appreciation, movie appreciation, games, and the Internet.
[0159]
FIG. 10F illustrates a digital camera, which includes a main body 2501, a display portion 2502, an eyepiece portion 2503, operation switches 2504, an image receiving portion (not shown), and the like.
[0160]
FIG. 11A illustrates a mobile phone, which includes a main body 2901, an audio output unit 2902, an audio input unit 2903, a display unit 2904, operation switches 2905, an antenna 2906, an image input unit (CCD, image sensor, and the like) 2907, and the like.
[0161]
FIG. 11B illustrates a portable book (e-book) including a main body 3001, display portions 3002 and 3003, a storage medium 3004, operation switches 3005, an antenna 3006, and the like.
[0162]
As described above, the applicable range of the present invention is extremely wide, and the present invention can be applied to manufacturing methods of electronic devices in all fields. Further, the electronic device of this embodiment can be realized by using any combination of Embodiment Modes 1 to 3 and Embodiments 1 to 3.
[0163]
【The invention's effect】
According to the present invention, light emitted in a lateral direction (a direction parallel to the substrate surface) out of light emitted from a layer containing an organic compound is reflected by a slope formed at a step portion of the first electrode, and is reflected in a certain direction (first direction). (The direction passing through the second electrode) can be increased. That is, it is possible to realize a light-emitting element in which light emission loss such as stray light is small.
[0164]
Further, according to the present invention, heat generated when the light-emitting element is driven is radiated through the semiconductor substrate, so that a highly reliable light-emitting element can be realized.
[0165]
Further, in addition to the light-emitting element, various circuits can be integrated on a semiconductor substrate, so that the semiconductor device can be significantly reduced in size.
[Brief description of the drawings]
FIG. 1 illustrates the first embodiment.
FIG. 2 is a diagram showing a first embodiment.
FIG. 3 is a view showing a first embodiment;
FIG. 4 illustrates a third embodiment.
FIG. 5 illustrates a second embodiment.
FIG. 6 is a diagram showing a second embodiment.
FIG. 7 is a diagram showing a second embodiment.
FIG. 8 is a diagram showing a system block diagram of an electronic device incorporating a light emitting device.
FIG. 9 shows a third embodiment.
FIG. 10 illustrates an example of an electronic device.
FIG. 11 illustrates an example of an electronic device.
FIG. 12 is a graph showing the reflectance of an aluminum film containing a small amount of Ti and the reflectance of a TiN film (100 nm).
FIG. 13 is a graph showing a change in work function with UV ozone treatment time.

Claims (24)

A first electrode connected to a field-effect transistor provided on a semiconductor substrate;
An insulator covering an end of the first electrode;
A light-emitting element including a layer containing an organic compound in contact with the first electrode and a second electrode in contact with the layer;
The first electrode has an inclined surface toward the center of the first electrode at an end of the first electrode, and the inclined surface reflects light emitted from the layer containing the organic compound. A semiconductor device characterized by the above-mentioned. A first electrode connected to a field-effect transistor provided on a semiconductor substrate;
An insulator covering an end of the first electrode;
A light-emitting element including a layer containing an organic compound in contact with the first electrode and a second electrode in contact with the layer;
A semiconductor device, wherein a central portion of the first electrode has a concave shape having a smaller thickness than an end portion. A first electrode connected to a field-effect transistor provided on a semiconductor substrate;
An insulator covering an end of the first electrode;
A light-emitting element including a layer containing an organic compound in contact with the first electrode and a second electrode in contact with the layer;
The semiconductor device according to claim 1, wherein the first electrode has a multilayer structure, and has a larger number of end portions than a center portion of the first electrode. A first electrode connected to the field effect transistor;
An insulator covering an end of the first electrode;
A light-emitting element including a layer containing an organic compound in contact with the first electrode and a second electrode in contact with the layer;
The first electrode has a depression, the width of the bottom of the depression is smaller than the width of the top of the depression, and the inclined surface of the depression reflects light emitted from the layer containing the organic compound. Characteristic semiconductor device. 5. The semiconductor device according to claim 1, wherein the second electrode is a light-transmitting conductive film. The semiconductor device according to claim 1, wherein the first electrode has a concave shape, and is formed in a self-aligned manner using the insulator as a mask. 7. The semiconductor device according to claim 1, wherein the first electrode is an anode, and the second electrode is a cathode. 7. The semiconductor device according to claim 1, wherein the first electrode is a cathode, and the second electrode is an anode. 9. The semiconductor device according to claim 1, wherein the first electrode is a part of a drain electrode or a source electrode of the field effect transistor. 9. The semiconductor device according to claim 1, wherein the first electrode is made of a different material from a drain electrode or a source electrode of the field effect transistor. 9. The device according to claim 1, wherein the first electrode has an inclined surface facing a central portion of the first electrode, and an inclination angle is more than 30 ° and less than 70 °. Characteristic semiconductor device. The insulator according to any one of claims 1 to 11, wherein the insulator covering an end of the first electrode has a curved surface having a radius of curvature at an upper end, and the radius of curvature is 0.2 μm to 3 μm. A semiconductor device, comprising: 13. The semiconductor device according to claim 1, wherein the layer containing the organic compound is a material that emits red light, a material that emits green light, or a material that emits blue light. 13. The semiconductor device according to claim 1, wherein the layer containing the organic compound is a material that emits white light, and is combined with a color filter provided in a sealing material. 13. The semiconductor device according to claim 1, wherein the layer containing the organic compound is a material that emits monochromatic light, and is combined with a color conversion layer or a coloring layer provided in a sealing material. The semiconductor device according to claim 1, wherein the field-effect transistor is a MISFET, a MOSFET, or a TFT. 17. The semiconductor device according to claim 1, wherein the semiconductor substrate is provided with a CPU, a memory element, a thin-film diode, a photoelectric conversion element, or a resistance element. 18. The semiconductor device according to claim 1, wherein the semiconductor device is a video camera, a digital camera, a goggle display, a car navigation, a DVD player, an electronic game device, or a portable information terminal. A method for manufacturing a semiconductor device including a light-emitting element having an anode, a layer containing an organic compound in contact with the anode, and a cathode in contact with the layer containing the organic compound,
Forming a field effect transistor on the semiconductor substrate;
Forming an insulator covering an end of a first electrode which is a part of a drain electrode or a source electrode of the field effect transistor;
Using the insulator as a mask, performing etching, and thinning a central portion of the first electrode so that a slope is exposed along an edge of the first electrode formed of a stacked metal layer;
Forming a film containing an organic compound in contact with a central portion and a slope of the first electrode;
Forming a second electrode made of a light-transmitting metal thin film on the film containing the organic compound. 20. The light emitting device according to claim 19, wherein the first electrode has a stack of a metal layer that reflects light and a metal layer that functions as an etching stopper, the metal layer that reflects light is etched, and the slope has light. A method for manufacturing a semiconductor device, wherein a reflective metal material is exposed. 21. The method for manufacturing a semiconductor device according to claim 19, wherein the first electrode is an anode, and is formed of a metal layer having a larger work function than the second electrode. 22. The first electrode according to claim 19, wherein the first electrode includes a first metal layer including titanium, a second metal layer including titanium nitride or tungsten nitride, and a third metal layer including aluminum. And a fourth metal layer containing titanium nitride. 23. The insulator according to claim 19, wherein the insulator covering an end of the first electrode has a curved surface having a radius of curvature at an upper end, and the radius of curvature is 0.2 μm to 3 μm. A method for manufacturing a semiconductor device. 24. The method according to claim 19, wherein the field-effect transistor is a MISFET, a MOSFET, or a TFT.

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