JP4091481B2 - Active matrix organic electroluminescent device and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an organic electroluminescent device, and more particularly, to an active matrix organic electroluminescent device using a thin film transistor.
[0002]
[Related technologies]
Currently, a cathode ray tube (CRT) is mainly used for a display device such as a television or a monitor. However, this has a problem in that it has a large weight and volume and a high driving voltage. Accordingly, the need for a flat panel display having excellent characteristics such as thinning, lightening, and low power consumption has emerged, and a liquid crystal display and a plasma display (plasma display) have been developed. Various flat panel displays such as display panels, field emission displays, and electroluminescent displays (ELDs) have been studied and developed.
[0003]
Among these, an electroluminescent element is a display element using an electroluminescence (EL) phenomenon in which light is generated when an electric field of a certain level or more is applied to a phosphor, and an inorganic electric field is generated by a source that causes excitation of carriers. A light emitting device and an organic electroluminescent device (OELD) can be classified into a light emitting device and an organic electroluminescent device (OELD).
[0004]
Among them, the organic electroluminescent element is attracting attention as a natural color display element because it emits light of all visible rays including blue, and has high luminance and low operating voltage characteristics. Further, since it is a self-luminous type, it has a large contrast ratio and can realize an ultra-thin display. On the other hand, the response time is about a few microseconds, the realization of moving images is easy, the viewing angle is not limited, it is stable even at low temperatures, and it is driven at a low voltage of DC 5V to 15V. And easy to design.
[0005]
Such an organic electroluminescent device has the same structure as that of an inorganic electroluminescent device. However, since the light emission principle uses light emission by recombination of electrons and holes, it is called an organic LED (organic light emitting diode: OLED). Sometimes. Therefore, it is called an organic LED below.
[0006]
Recently, an active matrix configuration in which a plurality of pixels are arranged in a matrix and a thin film transistor is connected to each pixel is widely used in flat panel display devices. Therefore, an active matrix in which this is applied to an organic electroluminescence device. An organic LED (active matrix organic LED: AMOLED) will be described with reference to the accompanying drawings.
[0007]
FIG. 1 illustrates a circuit structure of one pixel of an active matrix organic LED. As illustrated, one pixel of an active matrix organic LED includes a switching thin film transistor 4, a driving thin film transistor 5, and a storage capacitor. ) 6 and the light emitting diode 7. Here, the switching thin film transistor 4 and the driving thin film transistor 5 are p-type polycrystalline silicon thin film transistors.
[0008]
The switching thin film transistor 4 has a gate electrode connected to the gate line 1 and a source electrode connected to the data line 2. The drain electrode of the switching thin film transistor 4 is connected to the gate electrode of the driving thin film transistor 5, and the drain electrode of the driving thin film transistor 5 is connected to the anode electrode of the light emitting diode 7. The source electrode of the driving thin film transistor 5 is connected to the power line 3, and the cathode electrode of the light emitting diode 7 is grounded. Next, the storage capacitor 6 is connected to the gate electrode and the source electrode of the driving thin film transistor 5.
[0009]
Accordingly, when a signal is applied through the gate line 1, the switching thin film transistor 4 is turned on, and the signal of the data line 2 is transmitted to the gate electrode of the driving thin film transistor 5, and the driving thin film transistor 5 is turned on. Light is output. At this time, the storage capacitor 6 keeps the gate voltage of the driving thin film transistor 5 constant when the switching thin film transistor 4 is turned off.
[0010]
A cross section of a conventional active matrix organic LED using a thin film transistor in this way is shown in FIG. FIG. 2 is a sectional view of a driving thin film transistor, a light emitting diode, and a storage capacitor.
[0011]
As shown in the figure, a buffer layer 11 is formed on the substrate 10, and a first polysilicon layer 12 a, 12 b, 12 c and a second polysilicon layer having an island shape are formed on the buffer layer 11. 13a is formed. The first polycrystalline silicon layers 12a, 12b, and 12c are divided into an active layer 12a of the thin film transistor, a drain region 12b doped with impurities, and a source region 12c, and the second polycrystalline silicon layer 13a serves as a capacitor electrode.
[0012]
Next, a gate insulating film 14 is formed on the active layer 12a, and a gate electrode 15 is formed thereon.
[0013]
Subsequently, a first interlayer insulating film 16 is formed on the gate electrode 15 to cover the gate electrode 15, the source region 12c, the drain region 12b, and the capacitor electrode 13a, and on the first interlayer insulating film 16 above the capacitor electrode 13a. A power line 17 is formed at the end. Here, the power line 17 has a form of wiring and extends long in one direction.
[0014]
Next, a second interlayer insulating film 18 is formed on the power line 17. The second interlayer insulating film 18 together with the first interlayer insulating film 16 forms part of the drain region 12b and the source region 12c. A first contact hole 18a and a second contact hole 18b each representing, and a third contact hole 18c partially representing the power line 17 are provided.
[0015]
Next, a drain electrode 19 a and a source electrode 19 b are formed on the second interlayer insulating film 18. Here, the drain electrode 19a is connected to the drain region 12b through the first contact hole 18a, and the source electrode 19b is connected to the source region 12c and the power line 17 through the second contact hole 18b and the third contact hole 18c, respectively. Yes.
[0016]
Subsequently, a first protective layer 20 is formed on the drain electrode 19a and the source electrode 19b, and the first protective layer 20 has a fourth contact hole 20a that partially represents the drain electrode 19a.
[0017]
Next, an anode electrode 21 made of a transparent conductive material is formed on the first protective layer 20, and a second protective layer 22 is formed thereon. The second protective layer 22 has a recess 22 a that partially represents the anode electrode 21.
[0018]
Next, an organic light emitting layer 23 is formed on the recess 22a of the second protective layer 22, and a cathode electrode 24 made of an opaque conductive material such as metal is formed thereon. Here, the cathode electrode 24 is formed on the entire surface of the substrate.
[0019]
In the active matrix organic LED of FIG. 2, the anode electrode 21 is made of a transparent conductive material and the cathode electrode 24 is made of an opaque conductive material, so that light in the organic light emitting layer 23 is emitted downward through the anode electrode 23. . Therefore, it constitutes a bottom emission type.
[0020]
FIGS. 3A to 3G illustrate a process for manufacturing such an active matrix organic LED.
[0021]
As shown in FIG. 3A, after a buffer layer 11 is formed on a transparent substrate 10 and polycrystalline silicon is formed thereon, the polycrystalline silicon is patterned with a first mask to form an island-shaped semiconductor layer 12. , 13 are formed.
[0022]
Next, as shown in FIG. 3B, an insulating film such as a silicon oxide film is deposited on the semiconductor layers 12 and 13 and a conductive material such as a metal is deposited thereon, and then a second mask is used. The gate insulating film 14 and the gate electrode 15 are formed by patterning. Subsequently, an impurity is implanted into the semiconductor layer (12 and 13 in FIG. 3A) using the gate electrode 15 as a mask, the active layer 12a into which the impurity is not implanted, the drain region 12b and the source region 12c into which the impurity is implanted, and the capacitor electrode 13a. Form. Here, the drain region 12b and the source region 12c are disposed on both sides of the active layer 12a.
[0023]
Next, as shown in FIG. 3C, a first interlayer insulating film 16 is formed on the gate electrode 15, a conductive material such as a metal is deposited thereon, and then patterned with a third mask to form a capacitor electrode 13a. A power line 17 is formed on the top. The power line 17 forms a storage capacitor with the capacitor electrode 13a.
[0024]
Subsequently, as shown in FIG. 3D, a second interlayer insulating film 18 is formed on the power line 17 and is patterned using a fourth mask to thereby form first to third contact holes 18a, 18b, 18c is formed. The first contact hole 18a represents the drain region 12b, the second contact hole 18b represents the source region 12c, and the third contact hole 18c represents the power line 17.
[0025]
Next, as shown in FIG. 3E, a conductive material such as a metal is deposited on the second interlayer insulating film 18 and patterned with a fifth mask to form the drain electrode 19a and the source electrode 19b. The drain electrode 19a is connected to the drain region 12b through the first contact hole 18a, and the source electrode 19b is connected to the source region 12c and the power line 17 through the second contact hole 18b and the third contact hole 18c.
[0026]
Next, as shown in FIG. 3F, a first protective layer 20 is formed on the drain electrode 19a and the source electrode 19b, and this is patterned with a sixth mask to form a fourth contact hole 20a representing the drain electrode 19a. To do.
[0027]
Subsequently, as shown in FIG. 3G, a transparent conductive material is deposited and patterned using a seventh mask to form the anode electrode 21 connected to the drain electrode 19a through the fourth contact hole 20a.
[0028]
Next, as shown in FIG. 3H, a second protective layer 22 is formed on the anode electrode 21 and patterned with an eighth mask to form a recess 22a representing the anode electrode 21.
[0029]
Next, as shown in FIG. 3I, an organic light emitting layer 23 is formed on the concave portion 22a of the second protective layer 22, and an opaque conductive material such as metal is deposited thereon to form the cathode electrode 24. .
[0030]
An active matrix organic LED can be manufactured by such a method. However, in such an active matrix organic LED, since the power line takes a wiring form, there is a problem in dissipating the heat when the thin film transistor is driven. is there. Also, non-uniform image quality can occur when current is driven by wiring resistance.
[0031]
On the other hand, the active matrix organic LED is formed by repeating the process of vapor-depositing a thin film and performing photo etching using a mask many times, and the number of masks used at this time indicates the number of processes. Since the photo etching process involves various processes such as cleaning, photosensitive film coating, exposure and development, and etching, the manufacturing process, time and cost can be greatly reduced even if the number of masks is reduced by one. . By the way, in the case of the above-mentioned active matrix organic LED, since it must be manufactured using eight masks, since the manufacturing process is long, there are many causes of defects, which reduces the yield and costs. There is a problem that increases.
[0032]
In addition, since the active matrix organic LED has a plurality of thin film transistors and a storage capacitor in one pixel, and the storage capacitor is formed of an opaque material, the light emitting area is reduced and the aperture ratio is reduced. Thereby, in order to improve a brightness | luminance, since a current density increases, the lifetime of organic LED falls.
[0033]
Further, in the step of forming polycrystalline silicon on the entire surface of the substrate and patterning it in order to form the active layer, the etching selectivity between the grains constituting the polycrystalline silicon layer and the grain boundary is different. If all of this is to be etched, the etching time is extended and over etching is performed.
[0034]
However, a phenomenon occurs in which the surface of a part of the buffer layer exposed at the part already removed in the polysilicon in the over-etching process is scraped, so that all of the polycrystalline silicon is removed as a result. A crystalline form is left on the surface of the buffer layer.
[0035]
In such a case, when the gate insulating film and interlayer insulating film deposited on the buffer layer are formed, the shape left on the surface of the buffer layer is transferred as it is, and the ITO corresponding to the anode electrode The roughness of the electrode surface becomes worse.
[0036]
This is because after the organic light emitting layer and the cathode electrode are formed, a uniform field is not formed between the anode and the cathode due to the roughness during driving, and this causes a decrease in life. Further, the rectification ratio characteristic is not good due to the roughness of the surface, and it has a bad influence on gray reproduction at the time of active driving.
[0037]
[Problems to be solved by the invention]
The present invention has been devised in order to solve the above-described problems, and an object of the present invention is to prevent degradation of the power line and to provide an active matrix organic LED exhibiting uniform image quality and a method for manufacturing the same. Is to provide.
[0038]
Another object of the present invention is to provide an active matrix organic LED that can reduce the manufacturing process and cost, increase the aperture ratio, and have a long lifetime, and a method for manufacturing the same.
[0039]
Still another object of the present invention is to form a light emitting layer according to the surface roughness of the buffer layer by forming an interlayer insulating film with an organic insulating layer and forming a flat surface after forming a gate electrode and before forming a data wiring. It is an object of the present invention to provide an active matrix organic LED having a long lifetime of an organic light emitting layer and a method for manufacturing the same so that a field formed in the light emitting layer is uniform without being affected.
[0040]
[Means for Solving the Problems]
In order to achieve the above object, an active matrix organic electroluminescent device according to the present invention includes a substrate, a ground layer formed on the substrate, a buffer layer on the ground layer, and a buffer layer on the buffer layer. A polycrystalline silicon layer comprising an active region disposed in the center and drain and source regions disposed on both sides of the active region, a gate insulating film covering the polycrystalline silicon layer, and an upper portion of the polycrystalline silicon layer active region A gate electrode formed on the gate insulating film, a first capacitor electrode formed on the gate insulating film, an interlayer insulating film covering the gate electrode and the first capacitor electrode, and on the interlayer insulating film A first contact hole formed through the interlayer insulating film and the gate insulating film. And a drain electrode and a source electrode that are in contact with the drain region and the source region, respectively, through the second contact hole, formed on the interlayer insulating film, and connected to the drain electrode and on the interlayer insulating film. A second capacitor electrode formed, a protective layer formed on the interlayer insulating film, covering the drain and source electrodes, the cathode electrode and the second capacitor electrode, and having a recess representing the cathode electrode; An organic light emitting layer is formed in the upper portion of the layer and in the concave portion and contacts the cathode electrode through the concave portion, and an exposed portion of the protective layer and an anode electrode formed on the organic light emitting layer.
[0041]
Here, the gate electrode is electrically connected to the first capacitor electrode, and the gate electrode and the first capacitor electrode may be made of the same material.
[0042]
The source electrode may be connected to the ground layer through a third contact hole that penetrates the interlayer insulating film, the gate insulating film, and the buffer layer and represents a part of the ground layer.
[0043]
The second capacitor electrode may be connected to the ground layer through a third contact hole that penetrates the interlayer insulating film, the gate insulating film, and the buffer layer and represents a part of the ground layer.
[0044]
The anode electrode may be disposed on the entire surface of the substrate to serve as a power wiring.
[0045]
The first and second capacitor electrodes form a storage capacitor together with the interlayer insulating film disposed between the first and second capacitor electrodes.
[0046]
The drain region and the source region of the polycrystalline silicon layer are ion-doped, and the active region is made of pure silicon.
[0047]
Meanwhile, the ground layer preferably has a plurality of openings corresponding to the polycrystalline silicon layer.
[0048]
The ground layer may be formed of an opaque conductive material, and the opaque conductive material is preferably a metal.
[0049]
The cathode electrode, the drain electrode, the source electrode, and the second capacitor electrode may be made of the same material as the opaque conductive material, and the opaque conductive material is preferably a metal.
[0050]
The anode electrode may be made of a transparent conductive material that is one of indium-tin-oxide and indium-zinc oxide.
[0051]
In the present invention, the ground layer may be composed of a transparent conductive material, and the transparent conductive material is preferably composed of any one of indium-tin-oxide and indium-zinc oxide.
[0052]
The cathode electrode may be made of a transparent conductive material, and the transparent conductive material may be any one of indium-tin-oxide and indium-zinc oxide.
[0053]
The anode electrode may be made of an opaque conductive material such as a metal.
[0054]
Meanwhile, the drain electrode, the source electrode, and the second capacitor electrode may be formed of a double layer of a transparent conductive material and an opaque conductive material. In this case, the transparent conductive material includes indium-tin-oxide and indium-zinc oxide. The opaque conductive material may be a metal.
[0055]
The interlayer insulating film is preferably made of an organic material such as benzocyclobutene (BCB).
[0056]
The gate electrode is preferably disposed immediately above the active region.
[0057]
The method of manufacturing an active matrix organic electroluminescent device according to the present invention includes a step of forming a ground layer on a substrate, a step of forming a buffer layer on the ground layer, and a polycrystalline silicon layer on the buffer layer. Forming a gate insulating film covering the polycrystalline silicon layer, forming a gate electrode and a first capacitor electrode disposed on the polycrystalline silicon layer on the gate insulating film, and the gate Using the electrode as a mask, implanting ions into the polycrystalline silicon layer to form an active region disposed in the center, a drain region and a source region disposed on both sides of the active region, and the gate electrode and the first capacitor electrode, Forming a covering interlayer insulating film; and penetrating the interlayer insulating film and the gate insulating film and the drain region A first contact hole and a second contact hole respectively representing a source region; a third contact hole and a fourth contact hole representing a part of the ground layer through the interlayer insulating film, the gate insulating film and the buffer layer; Forming a drain electrode and a source electrode connected to the drain region and the source region through the first contact hole and the second contact hole, and forming the drain electrode and the source electrode on the interlayer insulating film, respectively. Forming a cathode electrode connected to the drain electrode; forming a second capacitor electrode on the interlayer insulating layer; covering the drain electrode, the source electrode, the cathode electrode, and the second capacitor electrode; Forming a protective layer having a recess representing an electrode; and an upper portion of the protective layer; Comprising the steps of forming an organic light-emitting layer in contact with the cathode electrode through said recess disposed in serial in the recess, and a step of forming an anode electrode on the organic emission layer upper.
[0058]
The gate electrode may be electrically connected to the first capacitor electrode, and the gate electrode and the first capacitor electrode may be made of the same material.
[0059]
The source electrode may be connected to the ground layer through the third contact hole, and the second capacitor electrode may be connected to the ground layer through the fourth contact hole.
[0060]
The anode electrode is disposed on the entire surface of the substrate and serves as a power wiring.
The first capacitor electrode and the second capacitor electrode form a storage capacitor together with the interlayer insulating film disposed between the first capacitor electrode and the second capacitor electrode.
[0061]
The drain region and the source region of the polycrystalline silicon layer are ion-doped, and the active region can be made of pure silicon.
[0062]
The ground layer preferably has a plurality of openings corresponding to the polycrystalline silicon layer.
[0063]
The ground layer may be made of an opaque conductive material such as metal.
[0064]
The step of forming the drain electrode and the source electrode, the step of forming the cathode electrode, and the step of forming the second capacitor electrode are preferably formed in the same mask process using the same opaque conductive material. The opaque conductive material may be a metal.
[0065]
The anode electrode may be made of a transparent conductive material such as indium-tin-oxide or indium-zinc oxide.
[0066]
The ground layer can be made of a transparent conductive material such as indium-tin-oxide or indium-zinc oxide.
[0067]
The step of forming the drain electrode and the source electrode, the step of forming the cathode electrode and the step of forming the second capacitor electrode are performed simultaneously using an opaque conductive material and using the same mask. Is desirable. At this time, the mask may include a slit at a position corresponding to the cathode electrode.
[0068]
The cathode electrode may be a single layer made of a transparent conductive material such as indium-tin-oxide or indium-zinc oxide.
[0069]
The drain electrode, the source electrode, and the second capacitor electrode may be formed of a double layer of a transparent conductive material and an opaque conductive material, and the transparent conductive material is one of indium-tin-oxide and indium-zinc oxide. The opaque conductive material may be made of metal.
[0070]
The anode electrode may be made of an opaque conductive material such as metal.
[0071]
The interlayer insulating film can be made of an organic material such as benzocyclobutene.
[0072]
The gate electrode is preferably disposed immediately above the polycrystalline silicon.
[0073]
As described above, in the present invention, the ground layer and the power line are formed on the entire surface of the substrate to minimize the heat dissipated during driving, thereby preventing deterioration and reducing the resistance to prevent uneven image quality. it can. Further, in the active matrix organic LED according to the present invention, the cathode electrode is formed in the same process as the source electrode and the drain electrode, thereby reducing the manufacturing process and cost, reducing the cause of defects, and increasing the manufacturing yield. it can.
[0074]
On the other hand, the present invention can be applied to all of the upper light emission method and the lower light emission method, and when using the upper light emission method, the aperture ratio increases, so that the lifetime of the organic LED can be increased.
[0075]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an active matrix organic LED and a method for manufacturing the same according to embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[0076]
FIG. 4 is a cross-sectional view of an active matrix organic LED according to a first embodiment of the present invention. As illustrated, a ground layer 120 made of a conductive material such as a metal is formed on the insulating substrate 110, and a buffer layer 130 is formed thereon. Polycrystalline silicon layers 131, 132, 133 having an island shape are formed on the buffer layer 130. The polycrystalline silicon layers 131, 132, 133 are formed of an active layer 131 of a thin film transistor and a drain region 132 doped with impurities. And a source region 133. Here, the ground layer 120 is formed on the entire surface of the substrate 110, and the buffer layer 130 is for preventing impurities from the substrate 110 from flowing into the active layer 131, the drain region 132, and the source region 133. A material such as a silicon oxide film can be used.
[0077]
Subsequently, a gate insulating film 140 is formed on the polycrystalline silicon layers 131, 132, and 133, and a gate electrode 151 is formed on the gate insulating film 140 on the active layer 131. A first capacitor electrode 152 made of the same material as the gate electrode 151 is further formed on the gate insulating film 140.
[0078]
Next, an interlayer insulating film 160 is formed on and covers the gate electrode 151 and the first capacitor electrode 152, and the interlayer insulating film 160 covers the first to fourth contact holes 161, 162, 163, 164. Have The first contact hole 161 and the second contact hole 162 extend to the gate insulating film 140 to represent the drain region 132 and the source region 133, respectively. The third contact hole 163 and the fourth contact hole 164 are the gate insulating film 140 and The ground layer 120 is shown extending to the buffer layer 130.
[0079]
Next, a cathode electrode 171, a drain electrode 172, a source electrode 173, and a second capacitor electrode 174 are formed on the interlayer insulating film 160 using an opaque conductive material such as metal. The cathode electrode 171 and the drain electrode 172 are connected, and the drain electrode 172 is connected to the drain region 132 through the first contact hole 161. The source electrode 173 is connected to the source region 133 and the ground layer 120 through the second contact hole 162 and the third contact hole 163, and the second capacitor electrode 174 is connected to the ground layer 120 through the fourth contact hole 164. Yes. Here, although not shown, the first capacitor electrode 152 is electrically connected to the gate electrode 151, and the first capacitor electrode 152 and the second capacitor electrode 174 form a storage capacitor. On the other hand, the cathode electrode 171 may be formed up to the top of the gate electrode 151.
[0080]
Next, a protective layer 180 is formed on the cathode electrode 171, the drain electrode 172, the source electrode 173, and the second capacitor electrode 174, and the protective layer 180 has a recess 181 that represents the cathode electrode 171.
[0081]
Subsequently, an organic light emitting layer 190 is formed on the concave portion 181 of the protective layer 180, on which indium-tin-oxide (hereinafter referred to as “ITO”) or indium-zinc oxide (hereinafter referred to as “IZO”). The anode electrode 200 made of a transparent conductive material is formed on the entire surface of the substrate. Here, the anode electrode 200 also serves as a power line.
[0082]
An equivalent circuit for such an active matrix organic LED of the present invention is shown in FIG. As shown in the figure, the gate wiring 212 and the data wiring 211 intersect, and a switching thin film transistor 214 is connected to the intersection between the gate wiring 212 and the data wiring 211. The drain electrode of the switching thin film transistor 214 is connected to the gate electrode of the driving thin film transistor 215, and the drain electrode of the driving thin film transistor 215 is connected to the cathode electrode of the light emitting diode 217. The source electrode of the driving thin film transistor 215 is grounded, and the anode electrode of the light emitting diode 217 is connected to the power line 213. Next, a storage capacitor 216 for keeping the gate voltage of the driving thin film transistor 215 constant is connected to the gate electrode and the source electrode of the driving thin film transistor 215.
[0083]
In the active matrix organic LED according to the present invention, the driving thin film transistor 215 is preferably an n-type thin film transistor, and the switching thin film transistor 214 may be an n-type thin film transistor or a p-type thin film transistor.
[0084]
As described above, in the first embodiment of the present invention, the ground layer and the power line layer are formed on the entire surface of the substrate, and FIG. 6 shows a plan view thereof. Here, elements such as a thin film transistor and a storage capacitor are omitted. As shown in the drawing, a ground layer 221 and a power line layer 222 are formed on the substrate 220, and the ground layer 221 and the power line layer 222 are formed on the entire surface of the substrate 220 so as to represent one side. A portion where the ground layer 221 and the power line layer 222 overlap is a region where an image is expressed, and a plurality of thin film transistors, storage capacitors, and light emitting diodes are formed. In the present invention, the power line layer 222 also serves as an anode electrode of the light emitting diode.
[0085]
As described above, in the first embodiment of the present invention, since the ground layer and the power line are formed on the entire surface of the substrate, the heat dissipated during driving can be minimized to prevent deterioration, and the resistance can be reduced to reduce the image quality. Can be prevented.
[0086]
In the first embodiment of the present invention, the lower cathode electrode is formed of an opaque conductive material, the upper anode electrode is formed of a transparent conductive material, and an upper emission method is used. Will increase. Therefore, since the luminance can be increased without increasing the current density during driving, the lifetime of the organic LED can be increased.
[0087]
A method of manufacturing the active matrix organic LED according to the first embodiment of the present invention is shown in FIGS. 7A to 7G.
[0088]
As shown in FIG. 7A, a conductive material such as a metal is deposited on the insulating substrate 110 and patterned with a first mask to form the ground layer 120. At this time, the ground layer 120 has a large area as shown in FIG. 6 and is formed over the entire image display area. Subsequently, a buffer layer 130 is formed on the ground layer 120 using a material such as a silicon oxide film, and then polycrystalline silicon is formed thereon and patterned with a second mask to form a semiconductor layer 135. Here, polycrystalline silicon can be formed by various methods, and an amorphous silicon layer is deposited and heat-treated, or a method of irradiating the amorphous silicon layer with a laser beam is used. Can be crystallized. In addition, the substrate 110 can be a transparent substrate such as glass, or can be an opaque substrate.
[0089]
Next, as shown in FIG. 7B, a gate insulating layer 140 is deposited on the semiconductor layer (135 in FIG. 7A), and then a metal-like material is deposited thereon and patterned using a third mask. As a result, the gate electrode 151 and the first capacitor electrode 152 are formed. Subsequently, impurities are implanted into both sides of the semiconductor layer (135 in FIG. 7A) using the gate electrode 151 as a mask, thereby forming the active layer 131 and the drain region 132 and the source region 133 on both sides of the active layer 131. At this time, the gate insulating film 130 can be formed of a silicon oxide film, or can be formed of a silicon nitride film. Although not shown, the first capacitor electrode 152 is electrically connected to the gate electrode 151.
[0090]
Next, as shown in FIG. 7C, an interlayer insulating film 160 is formed on the gate electrode 151 and the first capacitor electrode 152 by depositing an inorganic insulating material such as a silicon oxide film or an organic insulating material such as benzocyclobutene. Then, the first and fourth contact holes 161, 162, 163, and 164 are formed by patterning this together with the gate insulating film 140 and the buffer layer 130 using a fourth mask.
[0091]
At this time, the interlayer insulating layer 160 preferably functions to planarize the surface by applying an organic insulating material.
[0092]
This is because the surface of the buffer layer may be roughened in the step of patterning the polycrystalline silicon as described in the previous techniques.
[0093]
In other words, in the process of forming polycrystalline silicon on the entire surface of the substrate and patterning it, the etching selectivity of the grain and the grain boundary constituting the polycrystalline silicon layer formed on the substrate is different. If it is desired to etch all of the above, the etching time is extended and the over-etching process proceeds.
[0094]
By the way, if a phenomenon occurs in which the surface of a part of the buffer layer exposed at the part already removed in the polycrystalline silicon layer in the overetching process is scraped, and the polycrystalline silicon layer is completely removed. As a result, a crystalline form is left on the surface of the buffer layer.
[0095]
Therefore, the interlayer insulating film is formed so that the roughness of the surface of the buffer layer does not affect the light emitting layer to be formed thereafter (the effect of appearing on the light emitting layer due to the roughness of the transparent electrode transferred by the roughness of the insulating film). A step of flattening the surface by forming as an organic insulating layer is necessary.
[0096]
Next, as shown in FIG. 7D, a conductive material such as a metal is deposited on the interlayer insulating film 160 and patterned with a fifth mask to form the cathode electrode 171, the drain electrode 172, the source electrode 173, and the second capacitor electrode. 174 is formed. At this time, the cathode electrode 171 is connected to the drain electrode 172, the drain electrode 172 is connected to the drain region 132 through the first contact hole 161, and the source electrode 173 is connected to the source region through the second contact hole 162 and the third contact hole 163. 133 and the ground layer 120. The second capacitor electrode 174 is connected to the ground layer 120 through the fourth contact hole 164 and forms a storage capacitor together with the first capacitor electrode 152.
[0097]
Subsequently, as shown in FIG. 7E, a protective layer 180 is formed by depositing a material such as a silicon oxide film on the cathode electrode 171, the drain electrode 172, the source electrode 173, and the second capacitor electrode 174. A recess 181 representing the cathode electrode 171 is formed by patterning with the sixth mask.
[0098]
Subsequently, as shown in FIG. 7F, an organic light emitting layer 190 is formed on the recess 181 and a transparent conductive material such as ITO or IZO is deposited thereon to form the anode electrode 200. At this time, since the organic light emitting layer 190 is formed using an inkjet method or a shadow mask, and the anode electrode 200 is formed using a shadow mask, a photo etching process using a separate mask is not required.
[0099]
As described above, in the first embodiment of the present invention, the active matrix organic LED can be manufactured with six masks, so that the manufacturing process and cost can be reduced, the cause of failure can be reduced, and the manufacturing yield can be increased. .
[0100]
In the first embodiment of the present invention, the case where the upper light emission method is used has been described.
[0101]
Such an active matrix organic LED according to the second embodiment of the present invention is shown in FIG.
[0102]
As shown in FIG. 8, a ground layer 320 made of a transparent conductive material such as ITO or IZO is formed on an insulating substrate 310, and a buffer layer 330 is formed thereon. Polycrystalline silicon layers 331, 332, and 333 having an island shape are formed on the buffer layer 330. The polycrystalline silicon layers 331, 332, and 333 are thin film transistor active layers 331 and drain regions doped with impurities. 332 and a source region 333. Here, the ground layer 320 is formed on the entire surface of the substrate 310, and the insulating substrate 310 is preferably formed of a transparent substrate such as glass.
[0103]
Subsequently, a gate insulating film 340 is formed on the polycrystalline silicon layers 331, 332, and 333, and a gate electrode 351 and a first capacitor electrode 352 are formed on the gate insulating film 340. The capacitor electrode 352 is electrically connected to the gate electrode 351.
[0104]
Next, an interlayer insulating film 360 is formed on the gate electrode 351 and the first capacitor electrode 352 to cover them.
[0105]
At this time, the interlayer insulating layer 360 is formed of an organic insulating layer so as to flatten the surface.
[0106]
The interlayer insulating layer 360 includes first to fourth contact holes 361, 362, 363, and 364. The first contact hole 361 and the second contact hole 362 extend to the gate insulating layer 340, and each drain region. The third contact hole 363 and the fourth contact hole 364 extend to the gate insulating film 340 and the buffer layer 330 to represent the ground layer 320.
[0107]
Next, a cathode electrode 371, drain electrodes 372a and 372b, source electrodes 373a and 373b, and second capacitor electrodes 374a and 374b are formed on the interlayer insulating film 360. Here, the cathode electrode 371 is made of a transparent conductive material such as ITO or IZO and is connected to the drain electrodes 372a and 372b. The drain electrodes 372a and 372b, the source electrodes 373a and 373b, and the second capacitor electrodes 374a and 374b may be formed of a double layer of a lower transparent conductive material and an upper metal material. At this time, the drain electrodes 372a and 372b are connected to the drain region 332 through the first contact hole 361, and the source electrodes 373a and 373b are connected to the source region 333 and the ground layer 320 through the second contact hole 362 and the third contact hole 363. The second capacitor electrodes 374 a and 374 b are connected to the ground layer 320 through the fourth contact hole 364. The second capacitor electrodes 374a and 374b form a storage capacitor together with the first capacitor electrode 352.
[0108]
Next, a protective layer 380 is formed on the cathode electrode 371, the drain electrodes 372a and 372b, the source electrodes 373a and 373b, and the second capacitor electrodes 374a and 374b. Have.
[0109]
Subsequently, an organic light emitting layer 390 is formed on the concave portion 381 of the protective layer 380, and an anode electrode 400 made of an opaque conductive material such as metal is formed on the organic light emitting layer 390. Here, the anode electrode 400 also serves as a power line.
[0110]
As described above, in the second embodiment of the present invention, the ground layer and the power line are formed on the entire surface of the substrate, and the cathode electrode and the ground layer are formed of a transparent conductive material in order to prevent deterioration and make the image quality uniform. Then, the lower electrode method can be used by forming the anode electrode with an opaque conductive material.
[0111]
The active matrix organic LED according to the second embodiment of the present invention can be manufactured by the same method as the first embodiment. At this time, in order to form using six masks as in the first embodiment, a transparent conductive material and an opaque conductive material are sequentially deposited when forming a cathode electrode, a source electrode, a drain electrode, and a second capacitor electrode. After the photosensitive film is applied, exposure is performed using a mask in which a fine pattern such as a slit is formed in a portion where the cathode electrode is to be formed.
[0112]
On the other hand, as described above, the active layer, the source region, and the drain region are formed by depositing amorphous silicon and heat-treating it or crystallizing it by irradiating a laser beam. By the way, when the ground layer is formed on the entire surface of the substrate as in the present invention and amorphous silicon is formed thereon and then crystallized, the heat necessary to crystallize the amorphous silicon is heated. Since the dispersion is released by the ground layer having high conductivity, the time required for crystallization becomes long and crystallization is not performed properly. A photograph of the thin film crystallized at this time is shown in FIG. 9, but there is a problem that a thin film having a small crystal grain size can be obtained as shown in the figure and the device characteristics are deteriorated.
[0113]
In particular, when a laser beam is used, the crystal state becomes worse. This is because the crystallization method using a laser beam uses light energy, but the light energy is more easily dispersed by the ground layer. Because.
[0114]
Therefore, in order to solve such a problem, in another embodiment of the present invention, the thin film transistor, particularly the ground layer where the active layer and the source and drain regions are formed, is removed. FIG. 10 is a plan view of the ground layer according to this embodiment. As shown, the ground layer 421 according to another embodiment of the present invention has a plurality of openings 421a therein. As described above, the opening 421a corresponds to the position where the thin film transistor is formed.
[0115]
A photograph of the polycrystalline silicon layer formed using the ground layer of FIG. 10 is shown in FIG. 11, and it can be seen that a polycrystalline silicon layer having a large crystal grain size is formed as shown.
[0116]
The present invention is not limited to the above-described embodiments, and various changes and modifications can be made without departing from the spirit of the present invention.
[0117]
【The invention's effect】
In the present invention, the ground layer and the power line are formed on the entire surface of the substrate to minimize the heat dissipated at the time of driving, thereby preventing the deterioration and reducing the resistance to prevent the uneven image quality.
[0118]
Further, in the active matrix organic LED according to the present invention, the cathode electrode is formed in the same process as the source electrode and the drain electrode, thereby reducing the manufacturing process and cost, reducing the cause of defects, and increasing the manufacturing yield. it can.
[0119]
Further, in the present invention, since the interlayer insulating film interposed between the gate wiring and the data wiring is formed by the organic insulating layer, the electric field formation of the light emitting layer is made uniform by the surface flattening effect through the interlayer insulating film. The grain reproduction characteristic due to the rectification ratio characteristic can be improved, and at the same time, the lifetime of the light emitting layer can be extended.
On the other hand, the present invention can be applied to all of the upper light emission method and the lower light emission method, and when using the upper light emission method, the aperture ratio increases, so that the lifetime of the organic LED can be increased.
[Brief description of the drawings]
FIG. 1 is a circuit diagram of one pixel of an active matrix organic electroluminescent element in the related art.
FIG. 2 is a cross-sectional view of an active matrix organic electroluminescent device in the related art.
FIG. 3A is a cross-sectional view of a process product showing a manufacturing process of an active matrix organic electroluminescence device in the related art.
FIG. 3B is a cross-sectional view of a process product showing a manufacturing process of an active matrix organic electroluminescent device in the related art.
FIG. 3C is a cross-sectional view of a process product showing a manufacturing process of an active matrix organic electroluminescent device in the related art.
FIG. 3D is a cross-sectional view of a process product showing a manufacturing process of an active matrix organic electroluminescent device in the related art.
FIG. 3E is a cross-sectional view of a process product showing a manufacturing process of an active matrix organic electroluminescent device in the related art.
FIG. 3F is a cross-sectional view of a process product showing a manufacturing process of an active matrix organic electroluminescence device in the related art.
FIG. 3G is a cross-sectional view of a process product showing a manufacturing process of an active matrix organic electroluminescent device in the related art.
FIG. 3H is a cross-sectional view of a process product showing a manufacturing process of an active matrix organic electroluminescent device in the related art.
FIG. 3I is a cross-sectional view of a process product showing a manufacturing process of an active matrix organic electroluminescent element in the related art.
FIG. 4 is a cross-sectional view of an active matrix organic electroluminescent device according to a first embodiment of the present invention.
FIG. 5 is a circuit diagram of one pixel of an active matrix organic electroluminescent device according to the present invention.
FIG. 6 is a plan view schematically showing an active matrix organic electroluminescent device according to the present invention.
7A is a cross-sectional view of a process product showing a manufacturing process of an active matrix organic electroluminescent device according to the first embodiment of the present invention; FIG.
7B is a cross-sectional view of a process product showing a manufacturing process of an active matrix organic electroluminescent device according to the first embodiment of the present invention; FIG.
FIG. 7C is a cross-sectional view of a process product illustrating a manufacturing process of an active matrix organic electroluminescent device according to the first embodiment of the present invention.
FIG. 7D is a cross-sectional view of a process product illustrating a manufacturing process of an active matrix organic electroluminescent device according to the first embodiment of the present invention.
7E is a cross-sectional view of a process product showing a manufacturing process of an active matrix organic electroluminescent device according to the first embodiment of the present invention; FIG.
FIG. 7F is a cross-sectional view of a process product illustrating a manufacturing process of an active matrix organic electroluminescent device according to the first embodiment of the present invention.
FIG. 8 is a cross-sectional view of an active matrix organic electroluminescent device according to a second embodiment of the present invention.
FIG. 9 is a photograph of a polycrystalline silicon layer using a ground layer according to an embodiment of the present invention.
FIG. 10 is a plan view of a ground layer according to another embodiment of the present invention.
FIG. 11 is a photograph of a polycrystalline silicon layer using a ground layer according to another embodiment of the present invention.
[Explanation of symbols]
110: Substrate
120: Ground layer
130: Buffer layer
131: Active layer
132: Drain region
133: Source region
140: Gate insulating film
151: Gate electrode
152: First capacitor electrode
160: Interlayer insulating film
161, 162, 163, 164: contact holes
171: Cathode electrode
172: Drain electrode
173: Source electrode
174: Second capacitor electrode
180: protective layer
181: recess
190: Organic light emitting layer
200: Anode electrode

Claims (28)

Forming a ground layer on top of the substrate;
Forming a buffer layer on the ground layer;
Forming a polycrystalline silicon layer on the buffer layer;
Forming a gate insulating film covering the polycrystalline silicon layer;
Forming a gate electrode and a first capacitor electrode disposed on the polycrystalline silicon layer on the gate insulating film;
Implanting ions into the polycrystalline silicon layer using the gate electrode as a mask to form an active region located in the center and drain and source regions located on both sides of the active region;
Forming an interlayer insulating film covering the gate electrode and the first capacitor electrode;
A first contact hole and a second contact hole that penetrate through the interlayer insulating film and the gate insulating film to expose the drain region and the source region, respectively, and through the interlayer insulating film, the gate insulating film, and the buffer layer, the ground. Forming a third contact hole and a fourth contact hole exposing a portion of the layer;
Forming a drain electrode and a source electrode connected to the drain region and the source region through the first contact hole and the second contact hole, respectively, on the interlayer insulating film;
Forming a cathode electrode connected to the drain electrode on the interlayer insulating film;
Forming a second capacitor electrode on the interlayer insulating layer;
Covering the drain electrode, the source electrode, and the second capacitor electrode, and forming a protective layer so as to expose at least a part of the cathode electrode;
Forming an organic light emitting layer in contact with the exposed cathode electrode portion;
Forming an anode electrode on the protective layer and the organic light emitting layer,
The step of forming the drain electrode and the source electrode, the step of forming the cathode electrode, and the step of forming the second capacitor electrode are the same mask process using the same opaque conductive material. A method of manufacturing an active matrix organic electroluminescent device, characterized by comprising: The gate electrode, method for manufacturing an active matrix organic electroluminescent device according to claim 1, characterized in that it is electrically connected to the first capacitor electrode. The method of claim 2 , wherein the gate electrode and the first capacitor electrode are made of the same material. The source electrode, a manufacturing method of an active matrix organic electroluminescent device according to claim 1, characterized in that it is connected to the ground layer through the third contact hole. The method of claim 1 , wherein the second capacitor electrode is connected to the ground layer through the fourth contact hole. 2. The method of manufacturing an active matrix organic electroluminescent device according to claim 1 , wherein the anode electrode is disposed on the entire surface of the substrate and serves as a power wiring. The first capacitor electrode and the second capacitor electrode is active according to claim 1, characterized in that to form the interlayer insulating film and the storage capacitor together be placed between the first capacitor electrode and the second capacitor electrode -Manufacturing method of a matrix organic electroluminescent element. It said drain region and the source region of the polycrystalline silicon layer is ion doping method of an active matrix organic electroluminescent device of claim 1 wherein the active region, characterized in that it consists Jun粹silicon. 2. The method of manufacturing an active matrix organic electroluminescent device according to claim 1 , wherein the ground layer has a plurality of openings corresponding to the polycrystalline silicon layer. The method of claim 1 , wherein the ground layer is made of an opaque conductive material. The method of claim 10 , wherein the opaque conductive material is a metal. The method of claim 1 , wherein the opaque conductive material is a metal. The method of claim 10 , wherein the anode electrode is made of a transparent conductive material. The method of claim 13 , wherein the transparent conductive material is one of indium-tin-oxide and indium-zinc oxide. The method of claim 1 , wherein the ground layer is made of a transparent conductive material. The method of claim 15 , wherein the transparent conductive material is one of indium-tin-oxide and indium-zinc oxide. The forming of the drain electrode and the source electrode, the forming of the cathode electrode and the forming of the second capacitor electrode are performed simultaneously using an opaque conductive material and using the same mask. The method of manufacturing an active matrix organic electroluminescent device according to claim 15 , wherein The method of claim 17 , wherein the mask includes a slit at a position corresponding to the cathode electrode. The method of claim 18 , wherein the cathode electrode is formed of a single layer of a transparent conductive material. The method of claim 19 , wherein the transparent conductive material is one of indium-tin-oxide and indium-zinc oxide. 19. The method of claim 18 , wherein the drain electrode, the source electrode, and the second capacitor electrode are formed of a double layer of a transparent conductive material and an opaque conductive material. The active matrix organic electric field of claim 21 , wherein the transparent conductive material is made of any one of indium-tin-oxide and indium-zinc oxide, and the opaque conductive material is made of metal. Manufacturing method of light emitting element. The method of claim 15 , wherein the anode electrode is made of an opaque conductive material. The method of claim 23 , wherein the opaque conductive material is a metal. 2. The method of manufacturing an active matrix organic electroluminescent device according to claim 1 , wherein the interlayer insulating film is made of an organic material. The method according to claim 25 , wherein the interlayer insulating film is made of benzocyclobutene. 2. The method of manufacturing an active matrix organic electroluminescent device according to claim 1 , wherein the gate electrode is disposed immediately above the polycrystalline silicon. In the manufacturing method of the active-matrix organic electroluminescent element of Claim 1 ,
The ground layer and the anode electrode are planarly formed so as to cover at least two pixel regions among a plurality of pixel regions divided in a matrix by intersection of the gate electrode and the source electrode. A method of manufacturing an active matrix organic electroluminescent device.

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