9:45 AM - 10:00 AM
△ [18a-E304-2] Characterization of Low-temperature Poly-Si Thin-film Transistors Fabricated by Grain-Growth Controlled Selective-Laser-Annealing
Keywords:Low-temperature poly-Si (LTPS), Thin film transistor (TFT), Grain-growth control
Low-temperature poly-Si (LTPS) thin film is one of the promising channel materials for Si thin film transistors (TFTs). It exhibits higher mobility than amorphous Si (a-Si) and has the potential to be applied in both organic light-emitting diodes (OLEDs) and active-matrix liquid crystal displays (AMLCDs).
An essential process for LTPS fabrication is excimer laser annealing (ELA) using KrF or XeCl excimer lasers, which enable the crystallization of Si thin films with high performance and throughput. In particular, line-beam delivery systems scanning in the short-axis direction with multiple excimer laser sources are used commercially for small or medium substrates. Recently, a selective laser annealing (SLA) technique has been developed to respond to the demands of large-scale panel mass production such as G10.5. However, one remaining issue with this process is the difficulty of obtaining uniform TFT characteristics due to the random grain size and location.
In this study, we propose a method for fabricating high-stable TFTs with a KrF excimer laser. The location, size, and shape of poly-Si grains can be controlled precisely via a dot array mask and reduction projection lens without scanning exposure. In this process, a short wavelength of the KrF excimer laser (248 nm) is suitable owing to its high resolution. It is khown that a lateral solidification phenomenon is induced by unmelted seeds generated between high and low temperature Si. Several techniques have been proposed, such as sequential lateral solidification (SLS) and phase modulated excimer laser annealing (PMELA), for producing location-controlled single-crystal regions. Our approach is to improve the uniformity of poly-Si grain boundaries to fabricate stable TFTs. We report the characteristics of LTPS TFTs fabricated by SLA with a dot mask.
An essential process for LTPS fabrication is excimer laser annealing (ELA) using KrF or XeCl excimer lasers, which enable the crystallization of Si thin films with high performance and throughput. In particular, line-beam delivery systems scanning in the short-axis direction with multiple excimer laser sources are used commercially for small or medium substrates. Recently, a selective laser annealing (SLA) technique has been developed to respond to the demands of large-scale panel mass production such as G10.5. However, one remaining issue with this process is the difficulty of obtaining uniform TFT characteristics due to the random grain size and location.
In this study, we propose a method for fabricating high-stable TFTs with a KrF excimer laser. The location, size, and shape of poly-Si grains can be controlled precisely via a dot array mask and reduction projection lens without scanning exposure. In this process, a short wavelength of the KrF excimer laser (248 nm) is suitable owing to its high resolution. It is khown that a lateral solidification phenomenon is induced by unmelted seeds generated between high and low temperature Si. Several techniques have been proposed, such as sequential lateral solidification (SLS) and phase modulated excimer laser annealing (PMELA), for producing location-controlled single-crystal regions. Our approach is to improve the uniformity of poly-Si grain boundaries to fabricate stable TFTs. We report the characteristics of LTPS TFTs fabricated by SLA with a dot mask.