Development of alternative processes for top electrode deposition on OLED based on physical vapour deposition process

The large area fabrication of organic light emitting diode (OLED) requires a reliable and stable process for electrode deposition in order to extend the equipment uptime. Magnetron sputtering is candidated as a suitable metal deposition method, but serious damages in the OLED are generally observed. The degradation mechanisms based on the working principle of the magnetron sputtering are investigated using various measurements with variation of the process parameters. It is proved that the high leakage current is the result of metal penetration into the organic layers during the sputter process. With a special FTS-System (facing target sputtering), the aluminium deposition could be successfully demonstrated after the optimization of the process parameter. However, due to the very low deposition rate, the application of this process is difficult for the mass production. A bipolar pulsed double magnetron sputtering (DMS) also enables the metal deposition on the organic thin film device without damage, and, furthermore, the DMS system also allows a very short process time that it qualifies for a mass production. It is therefore expected that this method will be successfully applied to the fabrication of OLED lighting and displays.