Electrode patterning in OLED devices

Details Electrode patterning in OLED devices Electrode patterning in OLED devices

2002-09-06

2004-08-31

Fourson, George (Department: 2823)

Semiconductor device manufacturing: process

Making device or circuit emissive of nonelectrical signal

Mesa formation

C438S024000, C438S099000, C438S608000, C438S609000, C438S780000, C438S782000, C438S440000

Reexamination Certificate

active

06784009

ABSTRACT:

BACKGROUND OF INVENTION
FIG. 1
shows a conventional pixelated OLED device
100
. Pixelated OLED devices can be used as displays in various consumer electronic products, including cellular phones, cellular smart phones, personal organizers, pagers, advertising panels, touch screen displays, teleconferencing and multimedia products, virtual reality products, and display kiosks.
Typically, the OLED device comprises a functional stack of one or more organic functional layers
110
between a transparent conductive layer
105
and a conductive layer
115
. The functional stack is formed on a transparent substrate
101
. The conductive layers are patterned to form rows of cathodes in a first direction and columns of anodes in a second direction. OLED pixels are located where the cathodes and anodes overlap. Bond pads
150
are coupled to the cathodes and anodes to control the OLED pixels. A cap
160
, which forms a cavity
145
between it and the pixels, encapsulates the device to protect the OLED pixels from the environment such as moisture and/or air.
In operation, charge carriers are injected through the cathodes and anodes for recombination in the functional layers. The recombination of the charge carriers causes the functional layer of the pixels to emit visible radiation.
To provide a display with high resolution and high filling factor, the spacing between pixels should be small, for example, about less than 50 &mgr;m. The spacing between the pixels is defined by the patterning processes that form the cathodes and anodes. Various conventional patterning techniques have been used to form the cathodes, such as shadow masking, photolithography (with wet or dry etching), laser ablation, or lift-off techniques (wet or dry resists). However, conventional patterning techniques are not fully compatible or feasible for fabricating OLEDs. For example, photolithographic techniques employ chemicals which damage the organic functional layers or cathode materials. With shadow masking or lift-off techniques (wet resists as well as dry resist foils), high resolutions (e.g., less than 50 &mgr;m) are difficult to achieve, particularly in a manufacturing or production environment.
As evidenced from the above discussion, it is desirable to provide a patterning technique to pattern a conductive layer which achieves high resolutions without damaging already deposited materials.
SUMMARY OF INVENTION
The invention relates generally to the fabrication of devices such as OLED devices. More particularly, the invention relates to the patterning of a conductive layer. In one embodiment, pillars with an undercut (e.g., cross-section which is wider on top) are provided. In one embodiment, grooves between the pillars extend outside the electrode region to prevent shorting of adjacent electrodes. In another embodiment, the grooves extend to the edges of the substrate. The tapered profile of the pillars patterns the conductive layer into distinct first and second portions during deposition.


REFERENCES:
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patent: 5952778 (1999-09-01), Haskal et al.
patent: 5962970 (1999-10-01), Yokoi et al.
patent: 6111356 (2000-08-01), Roitman et al.
patent: 6373187 (2002-04-01), Nagayama et al.
patent: 2001/0000744 (2001-05-01), Wolk et al.
patent: 2001/0017516 (2001-08-01), Gonther

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