KR100599727B1 - A method for manufacturing capacitor in an organic electro-luminescence light emitting cell - Google Patents

Abstract

The present invention relates to a method of manufacturing a capacitor of an organic EL light emitting cell that can be applied to an organic EL light emitting display device of high resolution and size.

The capacitor of the organic EL light emitting cell according to the present invention, the insulating substrate; A polysilicon layer formed on the insulating substrate and separated into a first capacitor region and a second capacitor region; An insulating film formed on the polycrystalline silicon layer of the first capacitor region and the second capacitor region; And a metal wire formed on the gate insulating layer, wherein the polycrystalline silicon layer formed on the first and second capacitor regions is implanted with impurities.

According to the present invention, by forming a capacitor having a polysilicon layer electrode that can reduce the thickness to 1/6 or less than the capacitor of the conventional metal electrode, it is possible to realize a thickness reduction and high resolution display according to the enlargement of the light emitting display device In addition, in the case where two capacitors are formed in one organic EL pixel circuit, the layout and manufacturing process of the pixel circuit according to this become easy.

Organic EL, light emitting display, capacitor, pixel circuit

Description

A capacitor for an organic EL light emitting cell and a method of manufacturing the same {A method for manufacturing capacitor in an organic electro-luminescence light emitting cell}

1A and 1B are diagrams showing the light emission principle and organic EL light emitting cells of organic EL, respectively.

2 is a schematic block diagram of an organic EL display device.

3 is a diagram showing a general organic EL display panel using an active driving method using a TFT.

FIG. 4 is a diagram representatively showing one of N × M pixel circuits of the display panel of FIG. 3.

5 is a diagram illustrating a pixel circuit of an organic EL light emitting cell having two capacitors.

6 is a diagram showing the layout of a pixel circuit of an organic EL light emitting cell having two capacitors.

7 is a cross-sectional view of a capacitor formed in the organic EL light emitting cell according to the embodiment of the present invention.

8A to 8F are diagrams each showing a process of manufacturing a capacitor formed in an organic EL light emitting cell according to an embodiment of the present invention.

The present invention relates to a capacitor of an organic EL light emitting cell and a method of manufacturing the same, and more particularly, to a capacitor of an organic EL light emitting cell and a method of manufacturing the same which can be applied to an organic EL light emitting display device of high resolution and size.

An organic electroluminescence (EL) display device is a device for displaying an image by controlling an amount of current flowing through these organic materials by dividing an organic material emitting light when the current flows into pixels in a matrix form. Such an organic EL display device is expected to be a next generation display device due to advantages such as low voltage driving, light weight, wide viewing angle, and high speed response.

1A and 1B are diagrams showing the light emission principle and organic EL light emitting cells of organic EL, respectively.

In general, an organic EL display device is a display device for electrically exciting a fluorescent organic compound to emit light, and is capable of displaying an image by driving voltage or current by driving N × M organic light emitting cells. As shown in FIG. 1A, the organic light emitting cell structure has a structure of an indium tin oxide (ITO) pixel electrode, an organic thin film, and a metal layer, and the organic thin film has a good balance between electrons and holes to improve light emission efficiency. In order to achieve this, a multi-layer structure including an emitting layer (EML), an electron transport layer (ETL), and a hole transport layer (HTL) is formed, and a separate electron injection layer (Electron Injecting Layer: EIL) and a hole injecting layer (HIL). In addition, as shown in FIG. 1B, in the case of a top emission type organic EL light emitting cell, a metal anode, an organic thin film emission layer, and a transparent cathode may be formed on a silicon wafer.

As such a method of driving the organic light emitting cell, there are a simple matrix method and an active matrix method using a TFT. In the simple matrix method, the anode and the cathode are orthogonal and the line is selected and driven, whereas the active driving method is a driving method in which a TFT and a capacitor are connected to respective pixel electrodes to maintain a voltage by capacitor capacitance.

2 is a schematic block diagram of an organic EL display device.

Referring to FIG. 2, an organic EL display device may include a video controller 210, a panel controller 220, a power module 230, a scan driver 240, a data driver 250, and an organic EL panel 260. In this case, various signals passing through the analog interface and the digital interface are provided to the organic EL panel 260 in the column and row directions by the scan driver 240 and the data driver 250, respectively.

 Specifically, various analog signals such as R, G, B signals, and synchronization signals are input to the video controller 210 and then converted into digital signals, and the panel controller 220 controls them to sequentially scan the driver 240. And the data driver 250, the organic EL panel 260 is provided by the scan driver 240 and the data driver 250, and the power supply module 230. An N × M organic light emitting cell is driven by voltage or current by a power supply to represent an image.

3 is a view showing a general organic EL display panel using an active driving method using a TFT thin film transistor.

Referring to FIG. 3, the organic EL display device includes an organic EL display panel 310, a data driver 320, and a scan driver 330.

The organic EL display panel 310 includes m data lines D1, D2, ..., Dm extending in the column direction, n scan lines S1, S2, ..., Sn extending in the row direction, and N x M Pixel circuits. The m data lines D1, D2, ..., Dm transfer data signals representing an image signal to the pixel circuits, and the n scan lines S1, S2, ..., Sn transfer respective selection signals to the pixel circuits. . Here, the pixel circuit is formed in one pixel region 310-1 defined by two neighboring data lines D1, D2,..., And Dm and two neighboring scan lines S1, S2,..., Sn. For example, the transistors 311 and 312, the capacitor 313, and the organic EL element 314 are formed. Here, reference numeral 315 denotes Vdd, which is a power supply voltage.

The scan driver 330 sequentially applies a selection signal to the n scan lines S1, S2,..., And Sn, and the data driver 320 images an image on m data lines D1, D2,..., And Dm. The data voltage corresponding to the signal is applied.

In addition, the scan driver 330 and / or the data driver 320 may be electrically connected to the organic EL display panel 310, or a tape carrier adhered to and electrically connected to the organic EL display panel 310. The package may be mounted in a chip carrier package (TCP). Alternatively, the display panel 310 may be mounted in a flexible printed circuit (FPC) or a film that is adhered to and electrically connected to the display panel 310 in the form of a chip.

The scan driver 330 and / or the data driver 320 may be directly mounted on the glass substrate of the organic EL display panel 310, or may be formed of the same layers as the scan line, the data line, and the thin film transistor on the glass substrate. It may be replaced with the driving circuit formed or may be directly mounted.

FIG. 4 is a diagram representatively showing one of N × M pixel circuits of the display panel of FIG. 3.

As shown in Fig. 4, the pixel circuit includes an organic EL element OLED, two transistors SM and DM and a capacitor Cst. For example, the two transistors SM and DM may be formed as PMOS transistors.

The driving transistor DM has a source connected to the power supply voltage Vdd, and a capacitor Cst connected between the gate and the source. The capacitor Cst maintains the gate-source voltage of the driving transistor DM for a period of time, and the switching transistor SM has a data voltage from the data line Dm in response to a selection signal from the current scan line Sn. Is transferred to the transistor DM.

The organic EL element OLED has a cathode connected to a reference voltage Vss and emits light corresponding to a current applied through the driving transistor DM. Here, the power source Vss connected to the cathode of the organic EL element OLED is a voltage having a lower level than the power source Vdd, and a ground voltage or the like may be used.

However, in recent years, as the size of organic EL light emitting devices increases and the trend of high resolution increases, there is a need for manufacturing a thinner organic EL light emitting cell, but there is a problem that a conventional capacitor is formed to have a metal electrode having a considerable thickness. . In addition, recently, two capacitors are formed in one organic EL pixel circuit, which makes it difficult to design a pixel circuit layout, which causes a problem in that an enlargement of the organic EL light emitting display device is hindered.

An object of the present invention for solving the above problems is to provide a capacitor of an organic EL light emitting cell and a method of manufacturing the same that can reduce the thickness of the capacitor electrode to cope with the enlargement of the organic EL light emitting display device.

As a means for achieving the above object, the capacitor of the organic EL light emitting cell according to the present invention,

Insulating substrate;

A polysilicon layer formed on the insulating substrate and separated into a first capacitor region and a second capacitor region;

An insulating film formed on the polycrystalline silicon layer of the first capacitor region and the second capacitor region; And

Metal wiring formed on the gate insulating film

Including,

The polycrystalline silicon layer formed on the first and second capacitor regions is characterized in that the impurity is implanted.

Herein, the impurities are preferably P + high concentration impurities.

Here, the thickness of the polycrystalline silicon layer formed on the first and second capacitor regions is preferably 1000 kPa or less.

Herein, the capacitances of the capacitors formed in the first and second capacitor regions are different from each other.

Here, the polycrystalline silicon layer or the metal wiring may be the first or second electrode of the capacitor, and the insulating film may be a dielectric.

On the other hand, as another means for achieving the above object, the capacitor manufacturing method of the organic EL light emitting cell according to the present invention,

a) depositing an amorphous silicon layer on the insulating layer and converting it to a polycrystalline silicon layer by heat treatment;

b) separating the polycrystalline silicon layer into first and second capacitor regions;

c) depositing an insulating film over the polysilicon layer;

d) implanting impurities into the polycrystalline silicon layer on the first and second capacitor regions; And

e) forming metal wiring on the first and second capacitor regions

There is a feature consisting of.

Here, in step d), it is preferable to deposit P + high concentration impurities.

The first capacitor region may have a different size from the second capacitor region.

Here, step b) is characterized in that the polysilicon layer is separated into first and second capacitor regions by a photo and etching process, the separated region is insulated.

According to the present invention, by forming a capacitor having a polysilicon layer electrode that can reduce the thickness to 1/6 or less compared to a capacitor using a conventional metal electrode, it is possible to realize a thickness reduction and high resolution display according to the enlargement of the light emitting display device In addition, in the case where two capacitors are formed in one organic EL pixel circuit, the layout and manufacturing process of the pixel circuit according to it becomes easy.

Hereinafter, a capacitor and a manufacturing method thereof of an organic EL light emitting cell according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 5 is a diagram illustrating a pixel circuit of an organic EL light emitting cell having two capacitors. The pixel circuit of FIG. 4 described above has two transistors and one capacitor, but five transistors M1 to M5 and two capacitors. It consists of capacitors Cst and Cvth.

As shown in Fig. 5, the current-driven transistor M1 is connected to the organic EL element OLED to supply current for emitting light. The amount of current in the current-driven transistor M1 is controlled by the data voltage applied through the switching transistor M2. At this time, a capacitor Cst for maintaining the applied voltage for a predetermined period is connected between the source and the gate of the transistor M1. The selection signal line Sn is connected to the gate of the switching transistor M2, and the data line Dm is connected to the source side.

Referring to the operation of the pixel circuit having the above structure, when the transistor M2 is turned on by the selection signal Sn applied to the gate of the switching transistor M2, the data voltage Dm is driven through the data line. Is applied to the gate of M1). In response to the data voltage Dm applied to the gate, current flows through the driving transistor M1 to the organic EL element OLED to emit light. Here, M3 is a threshold voltage compensation transistor, Cst is a capacitor for maintaining the applied voltage for a certain period, and Cvth is a threshold voltage compensation capacitor. In addition, M5 represents a transistor for preventing IR drop.

As described above, when two capacitors Cst and Cvth are formed in one organic EL pixel circuit, it is necessary to consider the pixel circuit layout design accordingly.

FIG. 6 is a diagram showing the layout of a pixel circuit of an organic EL light emitting cell having two capacitors, and showing the layout of the pixel circuit shown in FIG.

As shown in FIG. 6, it is seen that the first capacitor Cst and the second capacitor Cvth are formed on the right side of the organic EL pixel circuit layout, are formed long in the longitudinal direction to increase the layout efficiency, and are separated from each other. Can be. In this case, the first electrodes of the first capacitor Cst and the second capacitor Cvth are formed of a polycrystalline silicon layer, which will be described in detail with reference to FIGS. 7 and 8A to 8F.

7 is a cross-sectional view of a capacitor formed in an organic EL light emitting cell according to another embodiment of the present invention.

Referring to FIG. 7, the capacitor of the organic EL light emitting cell according to the embodiment of the present invention includes an insulating substrate 511, polycrystalline silicon layers 513a ′ and 513b ′, a gate insulating film 514, and a gate metal wiring 515a. , 515b), wherein the polycrystalline silicon layers 513a 'and 513b' formed on the first and second capacitor regions are implanted with P + high concentration impurities, and formed on the first and second capacitor regions. The thicknesses 513a 'and 513b' of the polycrystalline silicon layer are 1000 kPa or less.

Specifically, in the capacitor of the organic EL light emitting cell according to the embodiment of the present invention, the polysilicon layers 513a 'and 513b' are formed on the insulating substrate 511 and are separated into first and second capacitor regions.

The gate insulating layer 514 is formed on the polysilicon layers 513a 'and 513b' of the transistor region and the capacitor region, and the gate metal wirings 515a and 515b are formed on the gate insulating layer 514. have.

Here, the polycrystalline silicon layers 513a 'and 513b' of the first and second capacitor regions form a-Si: H on the insulating substrate 511 and convert the a-Si: H into a polycrystalline silicon layer by laser heat treatment. The polysilicon layers 513a 'and 513b' are separated into first and second capacitor regions by photo and etching processes, and are insulated from each other.

In addition, the capacitances of the capacitors Cvth and Cst formed in the first and second capacitor regions have different values, and the polysilicon layers 513a 'and 513b' or the metal wirings 515a and 515b are formed. Respectively become first or second electrodes of the first and second capacitors, and the insulating film 514 is formed of a dielectric having a predetermined dielectric constant.

8A to 8F are diagrams illustrating a process of manufacturing a capacitor formed in the organic EL light emitting cell according to the embodiment of the present invention, respectively.

Referring to FIGS. 8A to 8F, a process of manufacturing a capacitor formed in an organic EL light emitting cell according to an embodiment of the present invention is first performed on an insulating substrate 511 that is a silicon substrate or a glass substrate (Glass). Si: H (Hydrogenated amorphous Silicon: 512) is deposited by about 500 mW using plasma enhanced chemical vapor deposition (PECVD) (see FIG. 8A).

Then, the dehydrogenation process is performed by using a PECVD method, and crystallization is performed at 500 Pa by excimer laser annealing (ELA) (see FIG. 8B).

Specifically, when fabricating a poly-Si TFT on the insulating substrate 511, using a plasma enhanced chemical vapor deposition (PECVD) method to form an amorphous silicon layer (a-Si) thin film at a low temperature below 400 ℃ Deposit. When depositing an a-Si thin film by PECVD, since a large amount of hydrogen (H) is contained (about 10%) in the thin film, dehydrogenation (a) before recrystallization of a-Si: H (Hydrogenated amorphous Silicon) thin film is performed. Dehydrogenation must be performed. Subsequently, the excimer laser beam is irradiated to recrystallize the de-hydrogenated a-Si thin film 513 into the polycrystalline silicon layer.

Subsequently, a pattern is formed on the recrystallized polysilicon layer thin film 513 by using a first mask, and active layers 513a and 513b which are polycrystalline silicon layers are formed through dry etching (see FIG. 8C). That is, the polysilicon layer thin film 513 is separated into first and second capacitor regions by photo and etching processes. In this case, the first capacitor region has a different size from the second capacitor region, and the separated region is insulated.

Next, the gate insulating layer 514 is formed by depositing about 1000 mW of SiO ₂ on the entire surfaces of the active layers 513a and 513b, which are the polycrystalline silicon layers, and the silicon substrate 511 by using a PECVD method (FIG. 8D). Reference).

Next, a P + high concentration impurity is implanted into the insulating layer 514 on the first and second capacitor regions (see FIG. 8E). That is, P + impurities are coated on the insulating layer 514 on the first and second capacitor regions. In practice, the high concentration impurity may be N + ions as well as P + ions.

Next, gate metal wiring layers 515a and 515b are formed on the first and second capacitor regions (see FIG. 8F). That is, the gate metal wiring layers 515a and 515b are formed by depositing about 3000 Å of AlNd metal and about 600 을 of molybdenum (Mo) metal through a photo process and wet etching using a mask.

Accordingly, the polycrystalline silicon layer active layers 513a 'and 513b', the gate insulating layer 514, and the gate metal layers 515a and 515b form first and second capacitors, respectively. In this case, the polycrystalline silicon layer The active layers 513a 'and 513b' are polysilicon layer thin films, not conventional metals, and although the metal is conventionally formed about 6000 mW, the polysilicon layer thin film only needs to be formed about 1000 mW, so that the thickness of the capacitor is substantially It will be reduced by about 1/6.

As a result, as described above, the active layers 513a 'and 513b', which are the polysilicon layers, are polysilicon layer thin films which are not conventional metals, and the thickness of the capacitor is substantially about 1/6, and the organic EL light is emitted. As the thickness of the cell is reduced, it is possible to cope with the enlargement of the organic EL light emitting display device. In addition, in the case where two capacitors Cst and Cvth are formed in one organic EL pixel circuit, the layout and manufacturing process of the pixel circuit according to this becomes easy.

While the invention has been shown and described in connection with specific embodiments thereof, it will be appreciated that various modifications and changes can be made without departing from the spirit and scope of the invention as indicated by the claims. Anyone who owns it can easily find out.

According to the present invention, by forming a capacitor having a polysilicon layer electrode that can reduce the thickness to 1/6 or less than the capacitor of the conventional metal electrode, it is possible to realize a thickness reduction and high resolution display according to the enlargement of the light emitting display device .

Further, according to the present invention, when two capacitors are formed in one organic EL pixel circuit, the layout and the manufacturing process of the pixel circuit according to this become easy.

Claims (9)

Insulating substrate; A polysilicon layer formed on the insulating substrate and separated into a first capacitor region and a second capacitor region; An insulating film formed on the polycrystalline silicon layer of the first capacitor region and the second capacitor region; And Metal wiring formed on the gate insulating film Including, And a polycrystalline silicon layer formed on the first and second capacitor regions is impurity implanted. The method of claim 1, The impurity is a capacitor of an organic EL light emitting cell, characterized in that the P + high concentration impurity. The method of claim 1, The thickness of the polycrystalline silicon layer formed on the first and second capacitor region is 1000Å or less, the capacitor of the organic EL light emitting cell. The method of claim 1, Capacitors of the capacitors formed in the first and second capacitor regions are different from each other. The method of claim 1, Wherein the polycrystalline silicon layer or the metal wiring becomes the first or second electrode of the capacitor, and the insulating film is a dielectric. a) depositing an amorphous silicon layer on the insulating layer and converting it to a polycrystalline silicon layer by heat treatment; b) separating the polycrystalline silicon layer into first and second capacitor regions; c) depositing an insulating film over the polysilicon layer; d) implanting impurities into the polycrystalline silicon layer on the first and second capacitor regions; And e) forming metal wiring on the first and second capacitor regions Capacitor manufacturing method of an organic EL light emitting cell comprising a. The method of claim 6, The d) step is a capacitor manufacturing method of an organic EL light emitting cell, characterized in that to deposit a high concentration of impurities P +. The method of claim 6, And wherein the first capacitor region has a different size from the second capacitor region. The method of claim 6, In the step b), the polycrystalline silicon layer is separated into first and second capacitor regions by a photolithography and an etching process, and the separated regions are insulated.

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