KR20060001377A - Oled with improved adhesion of pixel electrode in via hole - Google Patents

Abstract

The present invention discloses an organic light emitting display device which can prevent the peeling phenomenon of the lower electrode by increasing the adhesion of the lower electrode in the via hole.

An organic light emitting display device according to the present invention includes: a switching element formed on an insulating substrate and having at least an electrode connected to the pixel electrode; A first insulating layer formed on the substrate and having a first via hole exposing a portion of an electrode of the switching element; A second insulating film formed on the first insulating film and having a second via hole exposing a part of an electrode of the switching element; And a pixel electrode formed on the second insulating layer and connected to the exposed electrode of the switching device through the first and second via holes. The size of the second via hole is larger than the size of the first via hole, and the second via hole is formed to expose the first via hole. The first insulating film is a protective film made of at least one inorganic film selected from a nitride film and an oxide film, and the second insulating film is selected from an organic film of an imide series and an organic film of an acrylic series.

Description

OLED with improved adhesion of pixel electrode in via hole}

1 is a cross-sectional view of a conventional organic light emitting display device;

2 is a cross-sectional view of an organic light emitting display device according to an embodiment of the present invention;

3A is a view for explaining an increase in adhesion force of a pixel electrode in a via hole in the organic light emitting display device shown in FIG. 2;

3B is a view for explaining an increase in adhesion force in a via hole in an organic light emitting display device according to another embodiment of the present invention;

Explanation of symbols on the main parts of the drawings

200: glass substrate 210: semiconductor layer

225: gate electrode 241, 245: source / drain electrode 250: protective film 260: planarization film

255, 265: via hole 270: anode electrode

285: organic film layer 290: cathode electrode

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a self-luminous flat panel display, and more particularly, to an organic light emitting display having improved adhesion of pixel electrodes in a via hole.

1 illustrates a cross-sectional structure of a conventional organic light emitting display device.

Referring to FIG. 1, a buffer layer 110 is formed on an insulating substrate 100, and a switching element 130 is formed on the buffer layer 110. The switching element 130 includes a semiconductor layer 131 having a source / drain region (not shown), a gate electrode 132, and a thin film transistor having source / drain electrodes 134 and 135.

A passivation layer 140 having a first opening 145 exposing a portion of the drain electrode 135 of the source / drain electrodes 134 and 135 is formed on the interlayer insulating layer 120. On the passivation layer 140, a planarization layer 150 having a second opening 155 exposing a portion of the drain electrode 135 is formed.

A lower electrode 160 electrically contacting the drain electrode 135 through the via hole 157 is formed on the planarization layer 150. The lower electrode 160 includes a reflective film 161 and a transparent conductive film 165 made of a metal material as the pixel electrode. Although not shown in the drawing, an organic layer including an emission layer and an upper electrode as a cathode are formed on a substrate.

In the conventional organic light emitting display device as described above, the via hole 157 electrically connects one of the source / drain electrodes 134 and 135, that is, the pixel electrode which is the drain electrode 135 and the lower electrode 160. The first opening 145 formed in the passivation layer 140 and the second opening 155 formed in the planarization layer 150 are provided. The planarization film 150 is formed such that the size d12 of the second opening 155 is larger than the size d11 of the first opening 145, so that the passivation layer 140 is formed in the via hole 157. 150) completely covered.

In this case, the size of the first opening 145 refers to the cross-sectional length d11 of the portion exposed by the first opening 145 of the drain electrode 135, and the size of the second opening 155 refers to the drain. The cross-sectional length d12 of the portion of the electrode 135 exposed by the second opening 155 is denoted. In addition, since the size of the via hole 157 means the cross-sectional length of the portion of the drain electrode 135 exposed by the via hole 157, the size of the via hole 157 is determined by the size of the second opening d12. .

Accordingly, the passivation layer 140 made of the inorganic insulation material is completely covered by the planarization film 150 made of the organic insulation material, so that the lower electrode 160 has the drain electrode 135 through the second opening 155. Is electrically connected to and in contact with the organic planarization layer 160 at the side of the second opening 155.

As such, when the lower electrode 160 is formed on the organic flattening layer 160 having poor adhesion to the metal material, the lower electrode peels due to poor adhesion between the flattening layer 160 and the lower electrode 150. In particular, the sidewall of the via hole has a weak adhesive force between the planarization film and the lower electrode, so that the lower electrode is wet peeled off or a crack is generated or a defect is generated by ultrasonic waves during cleaning.

The present invention is to solve the problems of the prior art as described above, to increase the adhesion of the lower electrode in the via hole to prevent the peeling phenomenon of the lower electrode and to prevent the failure of the lower electrode The purpose is to provide.

In order to achieve the above object, a flat panel display device of the present invention comprises: a switching element formed on an insulating substrate, at least including an electrode connected to the pixel electrode; A first insulating layer formed on the substrate and having a first via hole exposing a portion of an electrode of the switching element; A second insulating film formed on the first insulating film and having a second via hole exposing a part of an electrode of the switching element; And a pixel electrode formed on the second insulating layer and connected to the exposed electrode of the switching device through the first and second via holes.

The size of the second via hole is larger than the size of the first via hole, and the second via hole is formed to expose the first via hole. The first insulating film is a protective film made of at least one inorganic film selected from a nitride film and an oxide film, and the second insulating film is selected from an imide organic film, an acrylic organic film, BCB and SOG.

The second via hole is formed to expose the first via hole and a portion of the first insulating layer so that the lower electrode is electrically connected to the exposed electrode of the switching device through the first via hole and through the first and second via holes. In contact with the exposed portion of the second insulating film. The switching device includes a thin film transistor including a semiconductor layer and a gate electrode formed on an insulating substrate, and a source / drain electrode connected to the semiconductor layer, wherein the electrode connected to the pixel electrode is a drain electrode. to be.

The lower electrode has a stacked structure of a reflective film and a transparent conductive film, so that the reflective film is electrically connected to the exposed electrode of the switching device through a first via hole and simultaneously exposed through the first and second via holes. In contact with the part.

The lower electrode includes a reflective film and a transparent conductive film, and the reflective film has an opening for exposing an electrode of the switching device, wherein the transparent conductive film of the lower electrodes includes an exposed electrode of the switching device through a first via hole and an opening; Electrical contact.

In addition, the flat panel display of the present invention comprises: a switching element formed on an insulating substrate and having at least an electrode connected to the pixel electrode; A first insulating layer formed on the substrate and having a first via hole exposing a portion of an electrode of the switching element; A second insulating film formed on the first insulating film and having a second via hole exposing a part of an electrode of the switching element; And a pixel electrode formed on the second insulating layer and connected to the exposed electrode of the switching device.

The pixel electrode includes a reflective film having an opening that exposes a portion of an electrode of the switching device, and a transparent conductive film connected to the exposed electrode of the switching device. The size of the second via hole is larger than the size of the first via hole, and the opening is at least equal to or larger than the first via hole and smaller than the second via hole.

The second via hole is formed to expose the first via hole and a portion of the first insulating layer, and the reflective layer of the lower electrode contacts the exposed portion of the first insulating layer through the first and second via holes, and the transparent conductive film Is electrically contacted with the exposed electrode of the switching element through the first via hole and the opening.

The reflective film of the lower electrode includes a film selected from A, Al alloy film, Ag, Ag alloy film, and the transparent conductive film is selected from ITO and IZO.

In addition, the flat panel display of the present invention includes a first conductive film formed on an insulating substrate; A first insulating film formed on the substrate and having a first opening for exposing a portion of the first conductive film; A second insulating film formed on the first insulating film and having a second opening for exposing a portion of the first conductive film; A second conductive film formed on the second insulating film and electrically connected to the first conductive film through the first and second openings, wherein the second opening is overlapped with at least a portion of the first opening. A portion of the first conductive layer and a portion of the first insulating layer are exposed.

The second conductive layer is formed to be electrically connected to the first conductive layer through a portion of the exposed first opening and to contact a portion of the second insulating layer through a portion of the exposed first opening. The first conductive film and the second conductive film are made of a metal material.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

2 is a cross-sectional view of an organic light emitting display device according to an embodiment of the present invention.

Referring to FIG. 2, a buffer layer 205 is formed on a transparent insulating substrate 200, and a semiconductor layer 210 is formed on the buffer layer 205. The buffer layer 205 is for preventing impurities or the like from penetrating into the semiconductor layer 210, and the semiconductor layer 210 is made of a polysilicon film. A gate insulating layer 220 is formed on the semiconductor layer 210 and the buffer layer 205, and a gate 225 is formed on the gate insulating layer 220.

Impurities of a predetermined conductivity type, for example, P-type impurities, are implanted into the semiconductor layer 210 to form source / drain regions 221 and 225 on both sides of the gate 225. An interlayer insulating film 230 is formed on the gate 225 and the gate insulating film 220, and the interlayer insulating film 230 is etched to expose a portion of the source / drain regions 221 and 225 to form a contact hole. 231) and 235.

Source / drain electrode materials are deposited on the contact holes 231 and 235 and the interlayer insulating film 230 and then patterned. Source / drain electrodes 241 and 245 contacting the exposed source / drain regions 221 and 225 are formed through the contact holes 231 and 235, respectively. A passivation film 250 made of an inorganic insulating film such as a nitride film is formed on the source / drain electrodes 241 and 245 and the interlayer insulating film 230.

The passivation layer 250 is etched to expose a portion of the drain electrode 245 among the source / drain electrodes 241 and 245 to form a first opening 251. A planarization film 260, such as an acrylic organic insulating film, an imide organic insulating film, BCB, SOG, or the like, is formed on the first opening 251 and the passivation layer 250, and the drain electrode 245 in the first opening 251 is formed. The planarization layer 260 is etched to expose a portion of the passivation layer 250 to form a second opening 265.

An ITO or IZO film is sequentially deposited on the via hole 267 and the planarization film 260 by using an AlNd and a transparent conductive film 275 as a reflective film 271, and then patterned to form a drain electrode 245 through the via hole 267. A lower electrode 270 that is a pixel electrode to be connected is formed. Al, Al alloy film, Ag, Ag alloy film in addition to AlN may be used as the reflective film 271.

The pixel isolation layer 280 is formed on the lower electrode 270 and the planarization layer 260, and the pixel isolation layer 280 is etched to expose a portion of the lower electrode 270. The organic layer 285 is formed on the lower electrode 270, and then an upper electrode 290, which is a cathode, is formed on the substrate.

In the organic light emitting display according to the exemplary embodiment as described above, the adhesion of the lower electrode 270 in the via hole 267 is enhanced with reference to FIG. 3A. FIG. 3A is a diagram illustrating the drain electrode 245 and the via hole 267 in the organic light emitting display device according to the exemplary embodiment.

Referring to FIG. 3A, the via hole 267 is to connect one of the pixel electrode 270 and one of the source / drain electrodes 241 and 245, that is, the drain electrode 245, to the passivation layer 250. And a first opening 255 having a size d21 and a second opening 265 having a size d22 formed in the planarization film 260. The size d22 of the second opening 265 is larger than the size d21 of the first opening 255 to completely expose the first opening 255 and to expose a portion of the passivation layer 250. do.

In this case, the size of the first opening 255 refers to the cross-sectional length d21 of the portion of the drain electrode 245 exposed by the first opening 255, and the size of the second opening 265 refers to the drain. The cross-sectional length d22 of the portion of the electrode 245 and the passivation layer 250 exposed by the second opening 265 is represented. In addition, since the size of the via hole 267 refers to the cross-sectional length of a portion of the drain electrode 245 exposed by the via hole 267, the size of the via hole 267 is determined by the size d21 of the first opening 255. ) Is determined by the size d22 of the second opening 265.

Accordingly, not only a portion of the drain electrode 245 is exposed by the via hole 267 but also a portion of the passivation layer 250 is exposed. Therefore, when the metal layer, for example, the reflective film 271 made of AlNd and the lower electrode 270 of the transparent conductive film 275 are formed on the planarization film 260 made of an organic insulating film, the via hole 267 is formed. Since the reflective film 271 is electrically connected to the exposed drain electrode 245 and is in contact with the exposed protective film 250, a metal electrode is formed on the inorganic insulating film, thereby improving adhesion of the lower electrode 270 in the via hole. .

FIG. 3B is a cross-sectional view of an organic light emitting display device according to another embodiment of the present invention, and is limited to the drain electrode and the via hole as shown in FIG. 3A.

Referring to FIG. 3B, an organic light emitting display device according to another embodiment of the present invention is manufactured in the manner as shown in FIG. 2, and only the structure of the lower electrode 270 is different from that of one embodiment.

That is, a thin film transistor including a semiconductor layer 210, a gate electrode 225, and source / drain electrodes 241 and 245 is formed on the insulating substrate 200 as a switching element, and then the source / drain electrodes A protective film 250 made of an inorganic insulating film is deposited on the 241 and 245 and the interlayer insulating film 230.

The protective layer 250 is etched to form a first opening 255 exposing a portion of the drain electrode 245 among the source / drain electrodes 241 and 245. A second opening may be formed on the passivation layer 250 including the opening 255 to form a planarization layer 260 made of an organic insulating layer and then etch it to expose a portion of the drain electrode 245 and a portion of the passivation layer 250. 265).

The via hole 267 includes a first opening 255 having a size d31 formed in the passivation layer 250 and a second opening 265 having a size d32 formed in the planarization film 260. A reflective film 271, such as AlNd, is deposited on the entire surface of the substrate and then patterned to expose a portion of the drain electrode 245 through the third opening 273. Al, Al alloy film, Ag, Ag alloy film may be used in addition to AlNd. As the planarization film, an imide organic insulating film, an acrylic organic insulating film, BCB, SOG, or the like is used.

A reflective film 271 having an opening 273 exposing a portion of the drain electrode 245 and a transparent conductive film 275 such as ITO and IZO are deposited on the planarization film 260 and then patterned to reflect the film 271. And a lower electrode 270 having a transparent conductive film 275. Thereafter, as in the exemplary embodiment, an organic layer including an emission layer and an upper electrode as a cathode are formed.

In this case, the reason why the opening 273 is formed in the reflective film 271 is at the interface between the drain electrode 245 and the reflective film 271 when the reflective film 271 and the drain electrode 245 are electrically connected through the via hole 267. The aluminum oxide film (Al2O3) is formed to prevent the increase in contact resistance. Therefore, the transparent conductive film 275 of the lower electrode 270 is to be contacted through the third opening 273 in the via hole 267.

In another embodiment, the size d32 of the second opening 265 is larger than the size d21 of the first opening 255 to completely expose the first opening 255, as well as the protective film 250. A part of) is also exposed. In addition, the size d33 of the third opening 273 of the reflective film 271 is smaller than the size d32 of the second opening 265 formed in the planarization film 260. In this case, the size of the third opening 273 means the cross-sectional length d33 of the portion exposed by the second opening 265 of the drain electrode 245 and the passivation layer 250.

If the size d33 of the third opening 273 is larger than the size of the second opening 265, the lower organic planarization film 260 is excessively etched during patterning of the reflective film 271, resulting in undercut. This is because the step coverage of the transparent conductive film 275 is poor, resulting in disconnection failure. Therefore, the third opening 273 formed in the reflective film 265 is formed to be smaller than the size d32 of the second opening 265 formed in the flattening film 260 to prevent defects of the transparent conductive film. In order to prevent an increase in resistance, it is preferable to form the same or larger than the size (d31) of the first opening 255 formed in the protective film 250.

Accordingly, in the via hole 267, the transparent conductive film 275 of the lower electrode 270 is electrically connected to the exposed drain electrode 245 to prevent an increase in contact resistance and to contact the exposed protective film 250. The adhesion of the lower electrode 270 in the inside is improved.

In the exemplary embodiment of the present invention, the first opening 255 of the passivation layer 250 is aligned to be completely overlapped with the second opening 265 of the planarization film 260, but the second opening of the planarization film 260 is aligned. 265 may be misaligned to overlap a portion of the first opening 255 of the passivation layer 250. In this case, a portion of the drain electrode 245 is exposed by the second opening 265 to provide an electrical connection with the lower electrode 270, and at least one side of the passivation layer 250 is exposed to expose the lower electrode 270. By making it form on this inorganic insulating film, adhesive force can be improved.

Further, in the exemplary embodiment of the present invention, the second opening 265 formed in the planarization film 260 is limited to the size of the first opening 255 formed in the passivation layer 250, but at least the drain electrode is formed. When the second opening 265 of the planarization film 260 is misaligned to overlap with a portion of the first opening 255 of the passivation layer 250 so that a portion of the 245 is exposed, the second opening 265 265 may be formed regardless of the size of the first opening 255. In this case, a portion of the drain electrode 245 is exposed by the second opening 265 to provide an electrical connection with the lower electrode 270, and at least one side of the passivation layer 250 is exposed to expose the lower electrode 270. ) Can be formed on the inorganic insulating film, thereby improving adhesion.

An embodiment of the present invention is applied to the case where an insulating film formed between a source / drain electrode and a pixel electrode is used as an organic flattening film. However, as another embodiment, an organic flattening film is used as an insulating film between conductive films such as metal wiring. Applicable to

In the organic light emitting display device of the present invention as described above, when the organic flattening film is formed on the inorganic protective film, the opening formed in the organic flattening film is formed larger than the opening formed in the inorganic protective film so that the lower electrode is formed on the sidewall of the via hole. By contacting the protective film, there is an advantage in that the peeling phenomenon of the lower electrode can be prevented.

In addition, when the lower electrode includes a reflective film and a transparent conductive film, the opening is formed so that the reflective film covers the organic flattening film, thereby reducing contact resistance and preventing undercut of the organic flattening film during the patterning process for forming the opening. Short failure of the lower electrode can be prevented.

Although the above has been described with reference to a preferred embodiment of the present invention, those skilled in the art will be able to variously modify and change the present invention without departing from the spirit and scope of the invention as set forth in the claims below. It will be appreciated.

Claims (12)

In a flat panel display device having a pixel electrode, A switching element formed on the substrate and having at least an electrode connected to the pixel electrode; A first insulating layer formed on the substrate and having a first via hole exposing a portion of an electrode of the switching element; A second insulating film formed on the first insulating film and having a second via hole exposing a part of an electrode of the switching element; A pixel electrode formed on the second insulating layer and connected to the exposed electrode of the switching element through the first and second via holes; And the second via hole is larger than the size of the first via hole, and the second via hole is formed to expose the first via hole. The method of claim 1, The first insulating film is a protective film composed of at least one inorganic film selected from a nitride film and an oxide film, and the second insulating film is a planarization film selected from an organic film of an imide series, an organic film of an acrylic series, BCB and SOG. Flat Panel Display. The method of claim 1, The second via hole is formed to expose the first via hole and a portion of the first insulating layer so that the lower electrode is electrically connected to the exposed electrode of the switching device through the first via hole and through the first and second via holes. And an exposed portion of the second insulating layer. The method of claim 1, The lower electrode has a stacked structure of a reflective film and a transparent conductive film, so that the reflective film is electrically connected to the exposed electrode of the switching device through a first via hole and simultaneously exposed through the first and second via holes. And a flat panel display device in contact with the portion. The method of claim 1, The lower electrode includes a reflective film and a transparent conductive film, and the reflective film has an opening for exposing an electrode of the switching device, wherein the transparent conductive film of the lower electrodes includes an exposed electrode of the switching device through a first via hole and an opening; A flat panel display comprising electrical contact. In a flat panel display device having a pixel electrode, A switching element formed on the substrate and having at least an electrode connected to the pixel electrode; A first insulating layer formed on the substrate and having a first via hole exposing a portion of an electrode of the switching element; A second insulating film formed on the first insulating film and having a second via hole exposing a part of an electrode of the switching element; A pixel electrode formed on the second insulating layer and connected to the exposed electrode of the switching element; The pixel electrode includes a reflective film having an opening that exposes a portion of an electrode of the switching device, and a transparent conductive film connected to the exposed electrode of the switching device. And the size of the second via hole is greater than the size of the first via hole, and the opening is at least equal to or larger than the first via hole and smaller than the second via hole. 7. The film of claim 6, wherein the first insulating film is a protective film made of at least one inorganic film selected from a nitride film and an oxide film, and the second insulating film is selected from an imide organic film, an acrylic organic film, a BCB film, and an SOG film. And a flattening film. The method of claim 6, The second via hole is formed to expose the first via hole and a portion of the first insulating layer, and the reflective layer of the lower electrode contacts the exposed portion of the first insulating layer through the first and second via holes, and the transparent conductive film And an electrical contact with the exposed electrode of the switching element through the first via hole and the opening. The method of claim 8, The reflective film of the lower electrode includes a film selected from Al, Al alloy film, Ag and Ag alloy film, the transparent conductive film is selected from ITO and IZO. A first conductive film formed on the substrate; A first insulating film formed on the substrate and having a first opening for exposing a portion of the first conductive film; A second insulating film formed on the first insulating film and having a second opening for exposing a portion of the first conductive film; A second conductive film formed on the second insulating film and electrically connected to the first conductive film through the first and second openings; The second opening exposes a portion of the first conductive film and a portion of the first insulating film to overlap at least a portion of the first opening, And the second conductive film is electrically connected to the first conductive film through a portion of the exposed first opening and contacted with a portion of the second insulating layer through a portion of the exposed first opening. Device. The method of claim 10, The first insulating film is a protective film composed of at least one inorganic film selected from a nitride film and an oxide film, and the second insulating film is a planarization film selected from an organic film of an imide series, an organic film of an acrylic series, BCB and SOG. Flat Panel Display. The method of claim 10, A flat panel display device, characterized in that the first conductive film and the second conductive film are metal materials.

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