TFT Array Process Architecture and Manufacturing Process Flow

Summary

Amorphous silicon (a‐Si)‐based thin‐film transistor‐liquid crystal display (TFT‐LCDs) were developed to adopt large glass substrates. For the mass production of poly‐silicon TFT‐LCDs, it is necessary to develop low‐temperature manufacturing techniques for compatibility with alumina borosilicate large glass substrates, rather than costly and small‐sized quartz wafers. The semiconductor and dielectric layers in the TFT device structure are normally deposited by plasma enhanced chemical vapor deposition (PECVD). Inverted staggered structure is the simplest and the most common structure of a‐Si TFT. The advantage of the metal oxide semiconductor (OS) is the process similarity between a‐Si TFT and OS TFT device fabrication. The system on glass (SOG) TFT‐LCD with low‐temperature polycrystalline silicon (LTPS) technology enables to spare the silicon driver integrated circuits (ICs) and to enhance the productivity by reducing the module process steps. The fabrication cost of LTPS LCD is higher than that of the a‐Si LCD due to the increased number of process steps and masks.