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The ultimate purpose of a display is hyper-realistic regeneration of the physical experience that mankind enjoys every day. The two main characteristics required to attain this goal are the picture quality and the design to meet such aspect. The enhancement of the picture quality is rendered by larger screen sizes and the pixel specifications that suffice higher definition. The former asks for technological innovation for lower RC delay and higher transistor performance. In order to reduce the RC delay, current research focuses on thicker conducting layers with lower stray capacitance and an advanced process architecture is needed for it. The architecture should include transistors with higher performance but at lower cost, which becomes possible by the oxide semiconductors compatible with the current mass production facility for the amorphous silicon-based thin film transistor (TFT) developed thus far. On the other hand, the latter should require a higher pixel density that demands smaller unit pixel size while each pixel should embrace a dark area by which the transistors and metal lines are not destabilized by light. However, the black matrix consumes a part of the unit space hence the size becomes more critical in the transmittance control at higher pixel densities. Therefore, a fine patterning with proper overlay margins are getting more important. Along with the picture quality, the design has also been one of the main driving forces that drove the transition from the era of CRTs to flat panel displays (FPDs). The keywords that defined the transition era are `slim' and `light'. In order to reduce the thickness of the displays, backlights evolved from direct type to edge type and nowadays active matrix organic light emitting diode (AMOLED) displays have enabled even thinner designs by removing the optical shutter and the back light unit (BLU). To allow higher degrees of freedom packed in small and light shape, various types of study on the flexible substrate- are actively ongoing.