ORGANIC ELECTRO-LUMINESCENT DISPLAY AND METHOD OF FABRICATING THE SAME

Abstract

Provided are an organic electro-luminescent display (“OELD”) and a method of fabricating the OLED. The OELD includes an organic light emitting diode (“OLED”), a driving transistor driving the OLED, and a switching transistor controlling an operation of the driving transistor. The driving transistor includes an active layer having a crystal structure grown in a direction parallel to a current channel of the driving transistor, and the switching transistor includes an active layer having a crystal structure grown in a direction perpendicular to a current channel of the switching transistor. Accordingly, the requirements for the switching transistor and the driving transistor can be satisfied in designing the OELD. Therefore, it is possible to efficiently fabricate a low-mobility switching transistor and a high-mobility driving transistor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features and advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which:

FIG. 1 illustrates the thermal distribution of an exemplary silicon island during a crystallization process of the exemplary silicon island, which is used in an exemplary organic electro-luminescent display (“OELD”) and a method of fabricating the OELD;

FIG. 2 illustrates a heat flow path through an exemplary silicon island and the creation and growth of a crystal nucleus;

FIG. 3 is a scanning electron microscope (“SEM”) image of an exemplary polysilicon according to the present invention;

FIG. 4 is an SEM image of a polysilicon obtained using a conventional method;

FIGS. 5A through 5F are perspective views illustrating an exemplary method of fabricating an exemplary polysilicon layer, which is used as an active layer of an exemplary transistor, according to an exemplary embodiment of the present invention;

FIG. 6A illustrates an equivalent circuit diagram of an exemplary OELD according to an exemplary embodiment of the present invention;

FIGS. 6B and 6C illustrate the crystal growth directions of active layers of exemplary switching and driving thin film transistors (“TFTs”), respectively, of the exemplary OELD illustrated in FIG. 6A;

FIG. 7A illustrates a layout diagram of a unit pixel of an exemplary OELD according to an exemplary embodiment of the present invention;

FIG. 7B illustrates a sectional view taken along line VII-VII of FIG. 7A, according to an exemplary embodiment of the present invention; and

FIGS. 8A through 8V are layout diagrams and corresponding sectional views illustrating an exemplary method of fabricating an exemplary OELD according to an exemplary embodiment of the present invention.

Claims

1. An organic electro-luminescent display comprising: an organic light emitting diode;a driving transistor driving the organic light emitting diode, the driving transistor including an active layer having a crystal structure grown in a direction parallel to a current channel of the driving transistor; anda switching transistor controlling an operation of the driving transistor, the switching transistor including an active layer having a crystal structure grown in a direction perpendicular to a current channel of the switching transistor.

2. The organic electro-luminescent display of claim 1, further comprising an electrically insulative and thermally conductive layer disposed under the active layers, the electrically insulative and thermally conductive layer formed of a material selected from a group consisting of aluminum ceramic, cobalt ceramic, and iron ceramic.

3. The organic electro-luminescent display of claim 2, wherein the electrically insulative and thermally conductive layer is aluminum ceramic and is one of Al2O3 and AlN.

4. The organic electro-luminescent display of claim 2, wherein the electrically insulative and thermally conductive layer is cobalt ceramic and is one of CoO and CO3N4.

5. The organic electro-luminescent display of claim 2, wherein the electrically insulative and thermally conductive layer is iron ceramic and is one of FeO, Fe2O3, Fe3O4, and Fe2N.

6. The organic electro-luminescent display of claim 1, wherein the width of the active layer of the switching transistor and the length of the active layer of the driving transistor are 4 microns or more.

7. The organic electro-luminescent display of claim 1, wherein the driving transistor has a higher mobility than the switching transistor.

8. A method of fabricating an organic electro-luminescent display including an organic light emitting diode, a driving transistor driving the organic light emitting diode, and a switching transistor controlling an operation of the driving transistor, the method comprising: forming an electrically insulative and thermally conductive layer on a substrate;forming a first silicon island for an active layer of the switching transistor on the electrically insulative and thermally conductive layer, wherein the first silicon island extends in a direction parallel to a current channel of the switching transistor;forming a second silicon island for an active layer of the driving transistor on the electrically insulative and thermally conductive layer, wherein the second silicon island extends in a direction perpendicular to a current channel of the driving transistor;crystallizing the first silicon island to form the active layer of the switching transistor that has a crystal structure grown in a direction perpendicular to the current channel of the switching transistor;crystallizing the second silicon island to form the active layer of the driving transistor that has a crystal structure grown in a direction parallel to the current channel of the driving transistor; andfabricating the switching transistor and the driving transistor using the active layers.

9. The method of claim 8, wherein the electrically insulative and thermally conductive layer, the electrically insulative and thermally conductive layer formed of a material selected from a group consisting of aluminum ceramic, cobalt ceramic, and iron ceramic.

10. The method of claim 9, wherein the electrically insulative and thermally conductive layer is aluminum ceramic and is one of Al2O3 and AlN.

11. The method of claim 9, wherein the electrically insulative and thermally conductive layer is cobalt ceramic and is one of CoO and CO3N4.

12. The method of claim 9, wherein the electrically insulative and thermally conductive layer is iron ceramic and is one of FeO, Fe2O3, Fe3O4, and Fe2N.

13. The method of claim 8, wherein crystallizing the first silicon island and the second silicon island is performed by excimer laser annealing.

14. The method of claim 13, wherein crystallizing the first silicon island and the second silicon island is performed with a laser energy density of 400 mJ/cm2 or more.

15. The method of claim 13, wherein the width of the active layer of the switching transistor and the length of the active layer of the driving transistor are 4 microns or more.

16. The method of claim 8, wherein the width of the active layer of the switching transistor and the length of the active layer of the driving transistor are 4 microns or more.