This procedure is applicable to the production of any thermally evaporable thin-film device including organic light emitting diode (OLED) displays, thin-film transistors, and bulk material, which currently makes use of "fine metal masking" or other crude patterning methods.
Traditional semiconductor fabrication technologies rely on photoresists that can be selectively removed by solvent rinses or washing. However, photoresists cannot be used with organic semiconductors as the physical, chemical, and mechanical properties of the substrate and photoresist materials are essentially indistguishable. Consequently, organic displays, solid state lighting, and photovoltaics all rely on crude patterning by shadow masking. The growth of these potentially revolutionary technologies is presently limited by manufacturing difficulties such as mask cleanliness, flexibility, and fragility for small feature sizes. This invention introduces a novel class of inert photoresists suitable for lift-off patterning of organic semiconductors on sub -µm length scales.
The substrate is cooled facilitating the collection of the resist material. The resist is patterned optically or by direct heating so that the desired material can be blanket deposited. The substrate is then warmed so that the resist sublimes, removing everything except the desired material. This method eliminates the need for shadow masks, multiple chamber evacuation cycles, and solvents that may degrade or damage some thin-films physically or chemically. A suitable thin-film material can be chosen for the temperature constraints and the resist heating method utilized. The method conveniently allows for different kinds of multiple layers to be deposited in the same fashion with ease.
- Eliminates shadow masks, chamber evacuation cycles, and solvents
- Convenient multi-layer deposition