Development of high rate and low temperature sputter-deposition method for the fabrication of oxide films on organic substrate

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In this study, we tried to clarify the mechanisms of the damages induced in the organic films(BAlq film) by the sputter-deposition of electrode TCO films, and developed a new damage-less sputter-deposition method for the formation of the electrode films in OLED. Results are summarized as follows;1) Irradiation of high energy electrons and ions to the BAlq film above energy of 50 eV induced significant reduction of PL intensity of the films. This indicates that suppression of such high energy particle bombardment to the organic film surface during sputter-deposition is necessary to reduce the degradation of light emitting properties of the organic film.2) It was confirmed that deposition of the electrode films by using a facing target sputtering(FTS) method instead of conventional magnetron sputtering was effective to reduce the damages in the organic films. But, it was found that small amount of high energy secondary electrons emitted from the end of the cathode target can arrive at the substrate surface in the FTS, and leads to a significant reduction of PL intensity of the organic film. Therefore, we achieved complete suppression of such high energy electron bombardment by the insertion of Al plate near the target electrode. In addition, reduction of the kinetic energy of the sputtered particles arrived at the substrate surface by increase in sputtering gas pressure above 8 mTorr, and/or use of Kr gas instead of Ar gas was effective to reduce the damages in the organic film.Finally, we succeeded to develop a sputtering system in which incidence of secondary electrons and high energy sputtered particles to the substrate surface are completely suppressed during film deposition. As a result, sputter-deposition of the electrode films without reduction of PL intensity was successfully realized. Currently, we have been trying to make organic EL devices by using this new sputter-deposition process to confirm its usefulness in the EL device.