Method for fabricating pixel structure of active matrix organic light-emitting diode

• US 7,575,966 B2
• Filed: 10/20/2008
• Issued: 08/18/2009
• Est. Priority Date: 12/29/2005
• Status: Active Grant

• Current Assignee: Industrial Technology Research Institute
• Original Assignee: Industrial Technology Research Institute
• Inventors: Lai, Chih-Ming, Yeh, Yung-Hui, Huang, Yi-Hsun
• Primary Examiner(s): Doan; Theresa T
• Application Number:
  US12/254,820
• Publication Number:
  US 20090068773A1
• Time in Patent Office: 302 Days
• Field of Search: 438/48, 438/30, 438/23, 438/149, 438/151, 438/153, 257/59, 257/72, 257/E21.094, 257/E21.104, 257/E21.372, 257/E51.001, 257/E51.052
• US Class Current: 438/153
• CPC Class Codes: H01L 27/1225 with semiconductor materials not belonging to the group IV of the periodic table, e.g. InGaZnO
• CPC Class Codes: H01L 29/7869 having a semiconductor body comprising an oxide semiconductor material, e.g. zinc oxide, copper aluminium oxide, cadmium stannate
• CPC Class Codes: H10K 59/1216 the pixel elements being capacitors
• CPC Class Codes: H10K 59/38 comprising colour filters or colour changing media [CCM]

Abstract

A method for fabricating an AMOLED pixel includes forming a transparent semiconductor layer on a substrate and forming a first channel layer of the switch TFT, a lower electrode of a storage capacitor and a second channel layer of a driving TFT. A first dielectric layer is formed over the substrate. A first opaque metal gate of the switch TFT, a second opaque metal gate of the driving TFT and a scan line are formed on the first dielectric layer. A first source and a first drain of the switch TFT are formed in the first channel layer and a second source and a second drain of the switch TFT are formed in the second channel layer. A patterned transparent metal layer is formed on the first dielectric layer. A data line is formed over the substrate. An OLED is formed over the substrate.

Claims

1. A method for fabricating a pixel of an active matrix organic light-emitting diode, comprising:

forming a patterned transparent semiconductor layer on a substrate to form at least one first channel layer of a switch thin film transistor, at least one lower electrode of a storage capacitor and at least one second channel layer of a driving thin film transistor, wherein the area of the storage capacitor lower electrode is about 50%˜

95% of the pixel area;

forming a first dielectric layer over the substrate to serve as a first gate dielectric layer of the switch thin film transistor, a dielectric layer of the storage capacitor and a second gate dielectric layer of the driving thin film transistor;

forming a first opaque metal gate of the switch thin film transistor, a second opaque metal gate of the driving thin film transistor and at least one scan line on the first dielectric layer;

forming a first source and a first drain of the switch thin film transistor in the first channel layer and forming a second source and a second drain of the driving thin film transistor in the second channel layer;

forming a patterned transparent metal layer on the first dielectric layer to serve as an upper electrode of the storage capacitor, wherein the area of the upper electrode is about 50%˜

95% of the pixel area;

forming a data line over the substrate electrically connected to the first source of the switch thin film transistor; and

forming an organic light-emitting diode over the substrate electrically connected to the second drain of the driving thin film transistor.

2. The method for fabricating the pixel of the active matrix organic light-emitting diode of claim 1, wherein the material of the transparent semiconductor comprises ZnO, Mg_xZn_1-xO, Cd_xZn_1-xO or CdO, or ZnO, Mg_xZn_1-xO, Cd_xZn_1-xO or CdO that have been doped with (a) an element that is univalent or (b) Ni;

or indium gallium zinc oxide (InGaZnO).

3. The method for fabricating the pixel of the active matrix organic light-emitting diode of claim 1, wherein the material of the transparent metal comprises indium tin oxide or indium zinc oxide.

4. The method for fabricating the pixel of the active matrix organic light-emitting diode of claim 1, wherein the step for forming the patterned transparent metal layer on the first dielectric layer includes forming the upper electrode of the storage capacitor, a first transparent metal gate of the switch thin film transistor and a second transparent metal gate of the driving thin film transistor.

5. The method for fabricating the pixel of the active matrix organic light-emitting diode of claim 4, wherein the step for forming the patterned transparent metal layer on the first dielectric layer is performed prior to the step for forming the first opaque metal gate of the switch thin film transistor, the second opaque metal gate of the driving thin film transistor and the scan line on the first dielectric layer.

6. The method for fabricating the pixel of the active matrix organic light-emitting diode of claim 4, wherein the step for forming the patterned transparent metal layer on the first dielectric layer is performed after the step for forming the first opaque metal gate of the switch thin film transistor, the second opaque metal gate of the driving thin film transistor and the scan line on the first dielectric layer.

7. The method for fabricating the pixel of the active matrix organic light-emitting diode of claim 1, wherein the organic light-emitting diode includes a white organic light-emitting layer and the step of the method further comprises forming a color filter on the substrate prior to forming the data line and the organic light-emitting diode but after forming the upper electrode of the storage capacitor.

8. The method for fabricating the pixel of the active matrix organic light-emitting diode of claim 7, further comprising a step for forming another color filter to cover the organic light-emitting diode after the step of forming the organic light-emitting diode.