Young-Rok Song

9.2: Sequential Lateral Solidification (SLS) Process for Large Area AMOLED

We have demonstrated that the sequential lateral solidification (SLS) technology can be utilized for the large area AMOLED. An optimized SLS process provides us with polycrystalline Si films with well-controlled grain size and location. The thin film transistors (TFTs) with SLS-processed Si films show high performance with desirable uniformity. 14″ WXGA (1280×RGB×768) AMOLEDs were fabricated with SLS-processed TFT backplanes. We utilized RGB evaporation process with fine metal mask. The novel delta pixel arrangement results in increased aperture ratio and wider FMM process window. The advantage of SLS process will be discussed.

PECVD‐based nanocrystalline‐silicon TFT backplanes for large‐sized AMOLED displays

— A 14.1-in. AMOLED display using nanocrystalline silicon (nc-Si) TFTs has been developed. Nanocrystalline silicon was deposited using conventional 13.56-MHz plasma-enhanced chemical vapor deposition (PECVD). Detailed thin-film characterization of nc-Si films was followed by development of nc-Si TFTs, which demonstrate a field-effect mobility of about 0.6–1.0 cm2/V-sec. The nc-Si TFTs show no significant shift in threshold voltage when over 700 hours of constant current stress is applied, indicating a stable TFT backplane. The nc-Si TFTs were successfully integrated into a 14.1-in. AMOLED display. The display shows no significant current decrease in the driving TFT of the 2T-1cap circuit because the TFTs are highly stable. In addition to the improved lifetime of AMOLED displays, the development of nc-Si TFTs using a conventional 13.56-MHz PECVD system offers considerable cost advantages over other laser and non-laser polysilicon-TFT technologies for large-sized AMOLEDs.

70.4: A 14.1inch AMOLED Display using Highly Stable PECVD based Microcrystalline Silicon TFT Backplane

We have developed a 14.1 inch AMOLED display using microcrystalline silicon (mc-Si) TFTs. Microcrystalline silicon was deposited using conventional 13.56MHz Plasma Enhanced Chemical Vapor Deposition (PECVD). Detailed thin film characterization of mc-Si films was followed by development of mc-Si TFTs which show a field effect mobility of around 0.7∼1.0cm2/V.s. The mc-Si TFTs show no significant shift in threshold voltage when applied with a long time constant current stress, indicating a stable TFT backplane. The mc-Si TFTs were successfully integrated in a 14.1 inch AMOLED display. The display shows no significant current decrease in the driving TFT of the 2T circuit, even after long time of lifetime tests. Along with improved lifetime for AMOLED display, the development of mc-Si TFTs using conventional 13.56 MHz PECVD system offers significant cost advantages over other laser or non-laser polysilicon TFT technologies for AMOLED.