KR100739144B1 - Front emitting oled device and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a top-emitting organic light emitting diode (OLED) device and a method of manufacturing the same. Since a conventional top-emitting AM OLED panel device is formed in a structure in which a thin cathode film is directly connected to a common electrode, a cathode thin film and a common electrode A large amount of current continuously flows in this connecting portion, which short-circuits the cathode thin film. If the cathode thin film is formed thick, the luminance of light transmitted through the outside is reduced and the quality of the device is deteriorated. There was a problem that can not satisfy all. In view of the above problems, the present invention allows the auxiliary cathode electrode to be further formed in the anode electrode forming process on the common electrode connected to the cathode electrode, and the cathode electrode is configured to be connected to the common electrode through the auxiliary cathode electrode, When driving, the current is concentrated on the auxiliary cathode electrode, so that even if the cathode electrode is made very thin, damages caused by current are prevented from occurring, thereby improving lifetime and reliability, and reducing the thickness of the cathode electrode to improve luminance. have.

Description

Top-emitting OLED element and method of manufacturing the same {FRONT EMITTING OLED DEVICE AND MANUFACTURING METHOD THEREOF}

1 is a plan view showing the structure of a conventional top-emitting AM OLED.

Figure 2a to 2d is a cross-sectional view showing a manufacturing process of a conventional top-emitting AM OLED.

Figure 3a to 3d is a cross-sectional view showing a manufacturing process of an embodiment of the present invention.

4 is a plan view of a top-emitting AM OLED device according to an embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

101: substrate 102: semiconductor active layer

103: source-drain region 104: gate insulating film

105: gate electrode 106: interlayer insulating film

107: metal electrode 107 ': common electrode

108: first insulating film 109: anode electrode

109 ': auxiliary cathode electrode 110: second insulating film

111: hole injection layer 112: hole transport layer

113: light emitting layer 114: electron transport layer

115: electron injection layer 116: cathode electrode

117: shield

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a top-emitting organic light emitting diode (OLED) device and a method of manufacturing the same. In particular, in the top-emitting active OLED device, a current is concentrated in a thin film cathode electrode connected to a common electrode to prevent damage. The present invention relates to a top-emitting organic light emitting diode (OLED) device and a method for manufacturing the same, wherein the auxiliary cathode electrode layer capable of assisting the thin film cathode electrode is added to the common electrode while maintaining the existing process.

Recently, various flat panel displays have been developed to reduce weight and volume, which are disadvantages of cathode ray tubes (CRTs). Such a flat panel display panel is based on a liquid crystal display (LCD), a field emission display (FED), a plasma display panel (PDP), and an organic electroluminescence (EL). Organic light emitting diode (OLED) displays; and the like.

Among these, the organic EL device (hereinafter referred to as OLED) is an exciton in which electrons and holes are injected by injecting electrons and holes into the light emitting layer from the electron injection electrode (cathode electrode) and the hole injection electrode (anode electrode), respectively. ) Emits light when it falls from the excited state to the ground state.

Due to this principle, unlike LCD, which is conventionally used as a thin display device, it does not need a separate light source, and thus has the advantage of reducing the volume and weight of the device. Since the reaction speed is 1000 times faster than LCD, afterimage display is performed. As a result, it is emerging as a next-generation display device.

According to the size of these OLEDs, various driving methods are used. Typically, medium- and large-sized OLED displays have an active matrix driving method (AM method), and active matrix driving methods and passive (Passive) methods in small OLED displays. ) Matrix driving method (PM method) is used in combination.

In the early OLED devices, many back-emitting structures in which light is emitted to the rear using a transparent substrate are used. However, in the case of AM OLED devices in which driving devices are to be formed in each cell, the size of the light emitting area is reduced, so that the driving devices are applied to the lower layer. Top emitting AM OLED structures are proposed that can increase the light emitting area by placing and forming a light emitting layer on the upper layer.

1 is a plan view showing a device structure of a conventional general top-emitting AM OLED, in which a light emitting area is formed in an area covering an area in which driving devices are formed, and a common electrode for driving a plurality of devices in an active matrix type; A ground electrode) is formed on the side of the cell and connected to the cathode electrode. Although not shown, it is noted that switching transistors, driving transistors, storage capacitors, and the like are formed in the light emitting portion and the non-light emitting portion.

2A to 2D illustrate a cross-sectional view of a conventional manufacturing process based on a cross-sectional view of the A-A 'section of FIG. In order to accurately explain the structure of the two sections are shown together.

First, as shown in FIG. 2A, basic driving elements are first formed on the substrate 1, and then an anode electrode is formed. That is, a semiconductor material pattern 2 such as polycrystalline silicon to be used as an active layer of a thin film transistor is formed on the substrate 1, and a gate insulating film 4 and a gate electrode 5 are formed thereon, and then the semiconductor material pattern is formed. The gate insulating film 4 is etched to expose some regions of (2). An impurity such as B and P is implanted into the exposed semiconductor material pattern 2 and then heat-treated to form a transistor using the corresponding portion as the source-drain region 3. In addition, the interlayer insulating film 6 is deposited on the entire upper surface of the structure, and the gate insulating film 4 and the interlayer insulating film 6 on the source-drain region 3 of the semiconductor material are partially etched to form a contact hole, and then a metal Is deposited and patterned to simultaneously form the metal electrode 7 and the common electrode 7 'used as the ground electrode. Subsequently, the first insulating layer 8 is formed high on the formed structure and then planarized, and the first insulating layer 8 is etched to expose the metal electrode 7 in the drain region, and then the anode electrode 9 is formed thereon. To form.

As shown in FIG. 2B, a second insulating layer 10 is formed on the entire upper surface of the structure and then patterned to partially expose the anode electrode 9. In this case, the second insulating layer 10 does not remain on the common electrode 7 ′.

As shown in FIG. 2C, a hole injection layer 11 and a hole transport layer 12 are formed as an organic common layer on the entire upper surface of the structure, and the R, G, and B light emitting layers 13 are formed using a shadow mask. Is deposited for each region, and then an electron transport layer 14 and an electron injection layer 15 are formed as an organic common layer on the entire upper surface thereof. During the process, the exposure of the exposed common electrode 7 ′ is maintained as it is.

 As shown in FIG. 2D, the cathode electrode 16 is formed on the entire surface thereof to complete the light emitting area, and to be in electrical contact with the common electrode 7 ′ to provide a voltage. 17) After forming, planarize. The common electrode 7 ′ may be connected to the pad part and used as a scan electrode.

Since the above-described conventional structure is a structure in which the cathode electrode 16 is directly connected to the common electrode 7, a large amount of current continuously flows through the cathode electrode 16 formed of a thin film, and thus the cathode is caused by the heat generated. It is easy to produce the case where 16 is damaged.

In practice, the cathode electrode 16 usually has a thickness of about 10 to 15 nm, which is because the light generated due to the characteristics of the top-emitting device is emitted through the cathode electrode 16 so as to reduce the thickness of the cathode electrode 16. This is because it cannot increase more than a certain level. Therefore, Ag having high conductivity may be used. If a lot of current flows continuously through the thin film, heat may be generated, thereby causing Ag atoms to move and aggregate, resulting in low durability.

Therefore, in the conventional structure, since a large amount of current continuously flows in the portion where the cathode electrode 16 is connected to the common electrode 7 ', the thickness of the cathode electrode 16 cannot be reduced below a certain level, which leads to a decrease in transmission characteristics. This means a decrease in luminance. Therefore, in the related art, the cathode electrode 16 having a thickness of 10 to 20 nm is formed in consideration of both proper luminance and lifetime, which in turn causes unsatisfactory results in both lifetime and luminance.

As described above, the conventional top emission type AM OLED panel device has a structure in which a thin cathode film is directly connected to the common electrode, so that a large amount of current continuously flows to the portion where the cathode thin film and the common electrode are connected to short the cathode thin film. When the cathode thin film is formed thick, the quality of the device is deteriorated because the luminance of light emitted through the outside is reduced and thus the quality of the device is deteriorated.

In view of the above problems, the present invention is to form an auxiliary cathode electrode in the anode electrode forming process on the common electrode connected to the cathode electrode, the cathode electrode is configured to be connected to the common electrode through the auxiliary cathode electrode, It is an object of the present invention to provide a top-emitting OLED device and a method of manufacturing the same, in which current is concentrated on the auxiliary cathode electrode during actual driving so that damage caused by current does not occur even when the cathode electrode is made very thin.

In order to achieve the above object, the present invention provides a driving device and a common electrode formed on a substrate; An insulating layer formed on the structure and having holes for exposing a portion of the driving element and a portion of the common electrode; An anode electrode formed to define a light emitting region on the insulating layer while being connected to a part of the driving element exposed by the hole of the insulating layer; A common electrode exposed by the hole of the insulating layer and an auxiliary cathode electrode formed on a part of the insulating layer; A plurality of organic material layers sequentially formed on the anode electrode; It is characterized in that it comprises a cathode electrode formed on the organic material layer and connected to the auxiliary cathode electrode.

In addition, the present invention comprises the steps of forming a semiconductor device and an insulating layer on a substrate; Forming a common electrode on the insulating layer and forming a planarization film on the entire surface of the device; Partially etching the planarization layer to expose the common electrode and a portion of the formed device; Forming an anode electrode by forming a metal material on the exposed common electrode and a portion of the planarization layer to form an auxiliary cathode, and forming a metal material on the exposed element and a portion of the planarization layer; Forming a plurality of organic material layers in order on the anode electrode; And forming a cathode on the organic material layer and on the auxiliary cathode.

Hereinafter, a configuration and an operation according to a preferred embodiment of the present invention will be described with reference to the accompanying drawings.

3A to 3D are cross-sectional views illustrating a manufacturing process of an embodiment of the present invention. As shown in FIG. 3A to 3D, the actual manufacturing process sequence is the same as in the prior art. The cathode auxiliary electrode may be further formed between the common electrode and the cathode electrode so that the flow is not concentrated on the cathode electrode. Of course, additional processes may be used, which will be readily understood through the description of the technical features of the present invention.

First, as shown in FIG. 3A, the auxiliary cathode electrode 109 ′ is further formed while the basic driving elements, the common electrode, and the anode electrode 109 are formed on the substrate 101. That is, a semiconductor material pattern 102, such as polycrystalline silicon, to be used as an active layer of a thin film transistor is formed on the substrate 101, and a gate insulating film 104 and a gate electrode 105 are formed thereon, and then the semiconductor material pattern is formed. The gate insulating layer 104 is etched to expose some regions of the 102. In addition, an impurity such as B or P is implanted into the semiconductor material pattern 102 and heat-treated to form a transistor using the corresponding portion as the source-drain region 103. Next, an interlayer insulating film 106 is deposited on the entire upper surface of the structure, and the gate insulating film 104 and the interlayer insulating film 106 on the source-drain region 103 of the semiconductor material are partially etched to form a contact hole. A metal electrode 107 is formed by depositing and patterning metal. At this time, the common electrode 107 'is also formed. The common electrode 107 'is used as a bus to which the cathode electrode of the OLED is connected, and is mainly connected to the ground electrode, and cathodes of a plurality of OLEDs are collectively connected to the same common electrode 107' to be driven simultaneously. OLED elements may be determined, and the common electrode 107 'acts as a scan electrode. Next, the first insulating layer 108 is formed high on the formed structure, and then planarized and the first insulating layer 108 is etched to expose the metal electrode 107 and the common electrode 107 'in the drain region. A metal electrode is formed on the upper portion and patterned to form an anode electrode 109 and an auxiliary cathode electrode 109 '. Here, the metal electrode 107 is exposed through the first hole 108a formed in the first insulating film 108, and the common electrode 107 ′ is formed in the second hole formed in the second insulating film 108. 108b). The first insulating layer 108 may be referred to as a planarization layer because it is used for planarization and insulation.

As can be seen from the above structure, in the exemplary embodiment of the present invention, the auxiliary cathode electrode 109 'is made of the same material as the anode electrode 109 on the common electrode 107', which is simply exposed and subsequently directly connected to the cathode electrode. The auxiliary cathode electrode 109 'is formed on the sidewall of the second hole 108b, the upper portion of the common electrode 107', and the upper portion of the first insulating layer 108. More specifically, the auxiliary cathode electrode 109 ′ formed on the first insulating film 108 is formed to extend to a position adjacent to the light emitting region of the light emitting structure to be formed thereafter, while maintaining electrical insulation. When the cathode is formed, most of the cathode electrode extending outside the light emitting region is positioned on the auxiliary cathode electrode 109 'so that the current mainly concentrated at the connection portion between the cathode electrode and the common electrode is not the auxiliary electrode. It flows through the electrode 109 '. This means that the thickness of the cathode electrode can be much thinner than the conventional case by the auxiliary cathode electrode 109 ', the cathode of the thin film is to improve the light emitting surface transparency of the device to increase the light efficiency Will have an effect.

The anode electrode 109 is used as an electrode of the OLED device that emits light, and because of the characteristics of the front-emitting OLED, the light must be reflected in the direction of the cathode by reflecting light, so that the Cr has a high reflectivity and work function and excellent conductivity. , Al, Mo, Ag, Au, and the like may be used, and the auxiliary cathode electrode 109 'formed at the same time in the same metal process also maintains the properties thereof, and thus the auxiliary cathode electrode 109' requiring high conductivity. Suitable for use as Of course, the auxiliary cathode electrode 109 ′ may be formed of a different material and thickness through a different metal process, but the auxiliary cathode electrode 109 ′ may be formed without changing the existing process through a single process. The manner of this embodiment is preferred. Here, a different metal process means a process different from the process of forming the anode electrode 109 in time, and the auxiliary cathode electrode 109 'can be formed by the same kind of process as the process of forming the anode electrode 109. In addition, the metal of different materials (or materials) may be a metal different from the material of the anode electrode 109 among Cr, Al, Mo, Ag, and Au.

Subsequent processes follow a similar method to existing processes and allow the formed auxiliary cathode electrode 109 'to be continuously exposed until the cathode is formed.

Thereafter, as shown in FIG. 3B, the second insulating layer 110 is formed on the planarized first insulating layer 108 on which the anode electrode 109 and the auxiliary cathode electrode 109 'are formed, and then patterned. A portion of the anode electrode 109 is exposed and all of the auxiliary cathode electrode 109 'is exposed.

As shown in FIG. 3C, the hole injection layer 111 and the hole transport layer 112 are formed as an organic common layer on the entire upper surface of the structure, and the R, G, and B light emitting layers 113 are formed by using a shadow mask. Is deposited for each region, and then an electron transport layer 114 and an electron injection layer 115 are formed as an organic common film on the entire upper surface thereof. In this case, the emission layer 113 is formed only in the emission region, and is not formed in the portion where the driving element is formed.

As shown in FIG. 3D, the cathode electrode 116 is formed on the structure. In this case, the cathode electrode 116 is formed on the entire light emitting area, a part of the non-light emitting area, and the auxiliary cathode electrode 109 ', and after depositing a few nm of aluminum, a few nm of Ag or Mg on top thereof is also deposited. A metal such as Ag can be formed by depositing a thickness of several nm. This is a case where the conventional cathode electrode material is used as it is, in the embodiment of the present invention can be formed to a thickness of 5nm or less. Conventionally, the cathode electrode is formed to have a thickness of 10 nm to 20 nm, so as to cover the current flow continuously generated in the contact portion with the common electrode, but in this embodiment, the weak portion is the auxiliary cathode electrode 109. Since the reinforcement is performed using '), the thickness of the cathode electrode 116 can be formed sufficiently thin. As another example, the cathode electrode 116 forms LiF / Al of about 1 nm, and a transparent conductive film (ITO, etc.) is formed on the cathode electrode 116, and thus the cathode electrode 116 according to the continuous current flow while significantly increasing the transmittance. ) Can be prevented. Note that A-A 'and B-B' indicated at the top of the illustrated figure indicate the position of the cross-sectional view in the plan view of FIG. 4 which follows.

After forming the structure as described above, a protective film, an adhesive layer and a cap may be further formed thereon.

FIG. 4 is a plan view showing the structure of an AM OLED panel after the process illustrated in FIG. 3D is completed. FIG. 4D illustrates a light emitting region formed in a cell region, a common electrode passing through the light emitting region, and a region including a common electrode. The placement of the auxiliary cathode electrode and the cathode electrode formed in both the emission region and the auxiliary cathode electrode may be confirmed.

In the illustrated case, it can be seen that the auxiliary cathode electrode extends from the common electrode to the periphery of the light emitting region defined by the anode electrode, the plurality of organic materials and the light emitting layer, and is sufficiently connected to the common electrode and the cathode electrode. Therefore, most of the current flowing to the common electrode flows to the auxiliary cathode electrode, and the cathode electrode disposed in the OLED element region is dispersed without excessive current directly flowing to the cathode, thereby extending the life of the cathode electrode and making the thickness thinner. The luminance efficiency is increased.

In addition, since it is not necessary to further form a separate layer to form such an auxiliary cathode electrode, the change of the process is small and the overall thickness of the device does not increase.

As described above, the top-emitting OLED device of the present invention and a method of manufacturing the same may further form an auxiliary cathode electrode in an anode electrode forming process on a common electrode connected to the cathode electrode, and the cathode electrode may be formed through the auxiliary cathode electrode. By concatenating with the common electrode, the current concentrates on the auxiliary cathode electrode during actual driving so that the damage caused by the current is not generated even if the cathode electrode is made very thin, thereby improving the life and reliability and improving the thickness of the cathode electrode. There is an effect of reducing the brightness can be improved.

Claims (12)

A driving element and a common electrode formed on the substrate; An insulating layer formed on the driving element and the common electrode and having a first hole exposing a portion of the driving element and a second hole exposing a portion of the common electrode; An anode electrode connected to a portion of the driving device exposed by the first hole and defining a light emitting area on the insulating layer; A common cathode exposed by the second hole, sidewalls of the second hole, and an auxiliary cathode electrode formed on a portion of the insulating layer; A plurality of organic material layers sequentially formed on the anode electrode; And a cathode electrode formed on the organic material layer and electrically connected to the auxiliary cathode electrode on an upper surface of the auxiliary cathode electrode. The OLED of claim 1, wherein the auxiliary cathode has the same material and thickness as the anode. The top emission type OLED device of claim 1, wherein the auxiliary cathode electrode has a material and a thickness different from that of the anode electrode. The top emission OLED device of claim 1, wherein the auxiliary cathode is formed of a metal having a high reflectance and a work function including Cr, Al, Mo, Ag, and Au. The top emission type OLED of claim 1, wherein the auxiliary cathode electrode extends to an upper portion of an insulating layer adjacent to a light emitting area defined by the anode electrode and a plurality of organic material layers, and surrounds the light emitting area. device. The top-emitting OLED device of claim 1, wherein the cathode comprises a LiF / Al thin film and a transparent conductive film. The top emission type OLED device according to claim 6, wherein the LiF / Al thin film is 5 nm or less. Forming a semiconductor device and an insulating layer on the substrate; Forming a common electrode on the insulating layer and forming a planarization film on the entire surface of the semiconductor device; Etching the planarization layer to form a first hole exposing a part of the semiconductor device and a second hole exposing the common electrode; Forming an anode electrode by forming a metal material on an upper surface of the exposed common electrode, sidewalls of the second hole, and a portion of an upper portion of the planarization layer, and forming an anode electrode on a portion of the upper portion of the planarization layer. Wow; Forming a plurality of organic material layers in order on the anode electrode; And forming a cathode electrode on the organic layer and on an upper surface of the auxiliary cathode electrode to be electrically connected to the auxiliary cathode electrode. The top emission OLED of claim 8, wherein the auxiliary cathode electrode further forms an insulating layer exposing all of the anode electrode while electrically insulating a part of the anode after forming the auxiliary cathode electrode and the anode electrode. Device manufacturing method. The method of claim 8, wherein the auxiliary cathode electrode and the anode electrode are formed simultaneously by the same metal process. The method of claim 8, wherein the auxiliary cathode electrode and the anode electrode are formed separately by different metal processes. The method of claim 8, wherein the auxiliary cathode electrode formed on the planarization layer is formed to extend to a region adjacent to the plurality of organic material layers.

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