Active solid-state devices (e.g. – transistors – solid-state diode – Organic semiconductor material
Reexamination Certificate
1999-06-25
2001-10-02
Lee, Eddie (Department: 2815)
Active solid-state devices (e.g., transistors, solid-state diode
Organic semiconductor material
C257S091000, C257S099000, C257S103000, C313S504000
Reexamination Certificate
active
06297516
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to deposition and patterning, methods for thin films, and more particularly to photolithographic patterning methods which are suitable for producing organic light emitting devices (OLEDs) suitable for commercial flat panel displays, and to vacuum deposited devices fabricated using such photolithographic patterning, methods. More specifically, the present invention provides a single patterning system that can be used to pattern the various layers that comprise a three color stacked OLED (SOLED) without removing the SOLED from vacuum.
BACKGROUND OF THE INVENTION
Organic light emitting devices, which make use of thin film materials that emit light when excited by electric current, are becoming an increasingly popular technology for applications such as flat panel displays. Popular OLED configurations include double heterostructure, single heterostructure, and single layer, as described in PCT Application WO 96/19792, which is incorporated by reference.
OLED's may be fabricated using shadow mask technology. However, it is difficult to accurately align multiple layers of deposited material using shadow masks, and the masks tend to clog. Moreover, it is difficult to fabricate features smaller than about 300 microns using a shadow mask, whereas OLEDs smaller than about 100 microns by 100 microns, and possibly smaller than about 10 microns by 10 microns, are preferred for a high resolution, full color flat panel display.
An array of 20 micron×20 micron polymer LEDs has been fabricated using direct photoablation with the 193 nm. emission of an eximer laser. S. Noach et al, Appl. Phys. Lett. 69, 3650, Dec. 9, 1996. While this dimension is suitable for a high resolution display, the low speed of laser photoablation are undesirable for commercialization.
Photolithographic patterning involves the use of a photoresist to create patterns in a material deposited on a substrate, and can be used to pattern materials and fabricate devices on a submicron scale, much smaller than can be achieved with shadow mask technology. Photolithographic patterning is also well suited to commercialization because it can be used to quickly fabricate large panels. However, the organic materials used to fabricate OLEDs may be quickly degraded from exposure to deleterious substances such as water, solvents, developers, and even atmospheric conditions. In particular, many of the chemicals used in photolithographic processing, such as solvents and developers used to wash away photoresist, may rapidly degrade such organic materials. Great care should be taken to ensure that the organic materials are not exposed to deleterious substances during the patterning of top electrodes and afterward.
U.S. Pat. No. 5,294,870 to Tang discloses the use of a series of parallel walls formed by photolithography prior to deposition of an organic EL layer such that photolithographic patterning steps or wet chemistry are not required after the organic EL medium is deposited.
It is known to use a multi-layer photoresist system with an overhang to deposit materials with sloped edges. W. R. Runyan & K. E. Bean, Semiconductor Integrated Circuit Processing Technology, p.560, Addison-Wesley, 1990. It is also known to use a photoresist system with an overhang to deposit small features, and to facilitate the lift-off of photoresist after material has been deposited in applications such as the fabrication of narrow gate gallium arsenide transistors.
SUMMARY OF THE INVENTION
A new processing method for patterning small features in organic thin films using photolithographic patterning is described. In this method all photolithographic processing steps are performed prior to organic film deposition. The organic films and electrodes that comprise a SOLED, or similar multi-electrode organic-based device, are then deposited in sequence without being removed from vacuum. This method avoids exposure of the organic layers to conventional photolithographic solvents, such as tri-chloroethylene, acetone, methanol, ethanol, and propanol, that can modify mechanical and electrical properties of organic thin films.
In accordance with an embodiment of the present invention, a method of fabricating an organic thin film device is provided that includes the steps of: creating a patterning system having an insulation layer and a photoresist layer with a photoresist overhang on a substrate having a plurality of contact pads; depositing through the patterning system a first electrode that electrically connects to a first contact pad of said plurality of contact pads; depositing through the patterning system a organic layer that electrically connects to the first electrode; and depositing through the patterning system a second electrode that electrically connects to the first organic layer and a second contact pad of said plurality of contact pads.
In accordance with an embodiment of the present invention, a method of fabricating a stacked organic thin film device is provided that includes the steps of: creating a patterning system having an insulation layer and a photoresist layer with a photoresist overhang on a substrate having a first contact pad, a second contact pad, a third contact pad, and a fourth contact pad; depositing through the patterning system a first organic layer that covers and electrically connects to the first contact pad; depositing through the patterning system a first electrode that electrically connects to the second contact pad and the first organic layer; depositing through the patterning system a second organic layer that electrically connects to the first electrode; depositing through the patterning system a second electrode that electrically connects to the third contact pad and the second organic layer; and depositing through the patterning system a third organic layer that electrically connects to the second electrode; depositing through the patterning system a third electrode that electrically connects to the fourth contact pad and the third organic layer.
In accordance with an embodiment of the present invention, a method of fabricating a stacked organic thin film device is provided that includes the steps of: creating a patterning system having an insulation layer and a photoresist layer with a photoresist overhang on a substrate having a first contact pad, a second contact pad, a third contact pad, and a fourth contact pad; depositing through the patterning system a first organic layer that covers and electrically connects to the first contact pad; depositing through the patterning system a first electrode that electrically connects to the second contact pad and the first organic layer; depositing through the patterning system a second organic layer that electrically connects to the first electrode; depositing through the patterning system a second electrode that electrically connects to the third contact pad and the second organic layer; depositing through the patterning system an insulating layer on top of the second electrode; depositing through the patterning system a third electrode on top of the insulating layer that electrically connects to the fourth contact pad, and is electrically insulated from the second electrode by the insulating layer; depositing through the patterning system a third organic layer that electrically connects to the third electrode; and depositing through the patterning system a fourth electrode that electrically connects to the second contact pad and the third organic layer.
REFERENCES:
patent: 3153166 (1964-10-01), Thornton, Jr. et al.
patent: 3303357 (1967-02-01), White
patent: 3813587 (1974-05-01), Umeda et al.
patent: 4005457 (1977-01-01), Hill et al.
patent: 4728519 (1988-03-01), Tanimoto
patent: 4883770 (1989-11-01), Dohler et al.
patent: 5294870 (1994-03-01), Tang
patent: 5585695 (1996-12-01), Kitai
patent: 5641611 (1997-06-01), Shieh et al.
patent: 5652067 (1997-07-01), Ito et al.
patent: 5663573 (1997-09-01), Epstein et al.
patent: 5821690 (1998-10-01), Martens et al.
patent: 5917280 (1999-06-01), Burrows et al.
patent: 5932895
Bulovic Vladimir
Burrows Paul
Forrest Stephen R.
Baumeister Bradley W.
Kenyon & Kenyon
Lee Eddie
The Trustees of Princeton University
LandOfFree
Method for deposition and patterning of organic thin film does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for deposition and patterning of organic thin film, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for deposition and patterning of organic thin film will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2554194