Method and apparatus for thermal jet printing

Abstract

The disclosure relates to a method for depositing films on a substrate which may form part of an LED or other types of display. In one embodiment, the disclosure relates to an apparatus for depositing ink on a substrate. The apparatus includes a chamber for receiving ink; a discharge nozzle having an inlet port and an outlet port, the discharge nozzle receiving a quantity of ink from the chamber at the inlet port and dispensing the quantity of ink from the outlet port; and a dispenser for metering the quantity of ink from the chamber to the inlet port of the discharge nozzle; wherein the chamber receives ink in liquid form having a plurality of suspended particles and the quantity of ink is pulsatingly metered from the chamber to the discharge nozzle; and the discharge nozzle evaporates the carrier liquid and deposits the solid particles on the substrate.

Description

[0001]The instant application claims priority to Provisional Application No. 60 / 944,000 entitled “METHOD AND APPARATUS FOR DEPOSITING FILMS,” filed Jun. 14, 2007, which is hereby incorporated herein by reference in its entirety.BACKGROUND[0002]1. Field of the Invention[0003]The disclosure relates to a method and apparatus for efficiently depositing patterns of films on a substrate. More specifically, the disclosure relates to a method and apparatus for depositing films on a substrate which may form part of an LED or other types of display.[0004]2. Description of Related Art[0005]The manufacture of organic light emitting devices (OLEDs) requires depositing one or more organic films on a substrate and coupling the top and bottom of the film stack to electrodes. The film thickness is a prime consideration. The total layer stack thickness is about 100 nm and each layer is optimally deposited uniformly with an accuracy of better than ±1 nm. Film purity is also important. Conventional app...

AI Technical Summary

Benefits of technology

[0015]In still another embodiment, the disclosure relates to a method for providing accurate deposition of ink on a substrate, the method comprising: providing a quantity of ink to a chamber, the ink having a plurality of suspended particles in a carrier liquid; metering at least a portion of the ink delivered from the chamber to an inlet of a discharge nozzle by activating a dispenser; receiving the metered ink at a discharge nozzle, the discharge nozzle having an inlet port and an outlet port; transporting the metered ink from the inlet port to the outlet port of the discharge nozzle forming substantially solid particles; and depositing the substantially solid particles from the outlet port of the discharge nozzle onto a substrate by energizing the discharge nozzle to pulsatingly eject at least a portion of the substantially solid particles onto the substrate.

Problems solved by technology

This process is inefficient, as the entire substrate must be coated, even though only the regions exposed through the shadow mask require a film.

Furthermore, the shadow mask becomes increasingly coated with each use, and must eventually be discarded or cleaned.

Finally, the use of shadow masks over large areas is made difficult by the need to use very thin masks (to achieve small feature sizes) that make said masks structurally unstable.

Furthermore, ink jet printing is conventionally limited to the use of single layer OLED film stacks, which typically have lower performance as compared to multilayer stacks.

The single-layer limitation arises because printing typically causes destructive dissolution of any underlying organic layers.

Finally, unless the substrate is first prepared to define the regions into which the ink is to be deposited, a step that increases the cost and complexity of the process, ink jet printing is limited to circular deposited areas with poor thickness uniformity as compared to vapor deposited films.

The material quality is also typically lower, due to structural changes in the material that occur during the drying process and due to material impurities present in the ink.

No conventional technique combines the large area patterning capabilities of ink jet printing with the high uniformity, purity, and thickness control achieved with vapor deposition for organic thin films.

Because ink jet processed single layer OLED devices continue to have inadequate quality for widespread commercialization, and thermal evaporation remains impractical for scaling to large areas, it is a major technological challenge for the OLED industry to develop a technique that can offer both high film quality and cost-effective large area scalability.

Each of these approaches is inefficient as compared to the direct deposition of the desired pattern, either because it wastes material or requires additional processing steps.

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