Low temperature polycrystalline silicon (LTPS) thin film transistors (TFTs) have the potential for peripheral circuits integration to realize system on panel (SOP) due to the higher mobility than the amorphous silicon (a-Si) TFTs. Polycrystalline silicon (poly-Si) affords the possibility of larger aperture ratio on pixel, thus increasing the light utilization efficiency and reducing power consumption for both active matrix liquid crystal display (AMLCD) and bottom emitting active matrix organic light emitting diode (AMOLED). Thus low cost, high performance and reliable LTPS TFT technologies are indispensable for high definition display. This thesis focuses on new techniques to further improve the performance of existing LTPS TFTs and the applications on active matrix displays.

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Low temperature polycrystalline silicon (LTPS) thin film transistors (TFTs) have the potential for peripheral circuits integration to realize system on panel (SOP) due to the higher mobility than the amorphous silicon (a-Si) TFTs. Polycrystalline silicon (poly-Si) affords the possibility of larger aperture ratio on pixel, thus increasing the light utilization efficiency and reducing power consumption for both active matrix liquid crystal display (AMLCD) and bottom emitting active matrix organic light emitting diode (AMOLED). Thus low cost, high performance and reliable LTPS TFT technologies are indispensable for high definition display. This thesis focuses on new techniques to further improve the performance of existing LTPS TFTs and the applications on active matrix displays.

A new type of inducing media slow-release (SR) Ni/Si oxide is presented. Compared to pure nickel induced crystallization poly-Si film, the nickel residua in slow-release metal induced lateral crystallization (SR-MILC) poly-Si film is greatly reduced, as a result, the leakage current of the poly-Si TFTs is reduced consequently. This SR-Ni/Si oxide provides a wider process window and can prevent the variation of process parameters among batches of poly-Si films. Based on p-channel SR-MILC poly-Si TFTs, the 180-stage shift register presents robust and high performance at speed, noise margin and device uniformity. A 3-inch TFT SOP-AMOLED panel is designed and successfully fabricated based on this SR-MILC poly-Si TFT technology.

Mask metal induced crystallization (MMIC) technology is further introduced. The nano-scaled silicon oxide mask can pre-define the crystalline nucleation locations. Poly-Si films composed of continuous zonal domain (CZD) in exactly the same width are obtained. TFT characteristics are extensively compared and show that the seeding regions have no significant impact on the device performance. Compared to large-grain and small-grain MIC TFTs, the CZD-TFTs exhibit better electrical characteristics than the small-grain MIC TFTs and better device uniformity than the large-grain MIC TFTs.

The design criteria for a 3-inch QVGA active matrix backplane for field sequential color (FSC) LCD are introduced, such as the pixel TFT, storage capacitance, data line and scan line, including the required material, layout, and process parameters and so on. A prototype FSC-LCD is constructed using the CZD-TFT backplane and a transient LCD mode. It works well and shows vivid colors in a field sequential manner.

Bridged-grain (BG) poly-Si technology is the bridging of the grains inside the active channel of the poly-Si TFT using parallel conductive bands or lines. The current flows transverse to the parallel lines and the grain boundary effects could be reduced. This technique can be applied to all the existing LTPS TFT technologies. We believe that the boundary height could be lowered by the BG structure, which means, some of the trap-states and dangling bounds could be filled or terminated by the dopants from the BG-lines. The leakage current could be dramatically reduced also by the serial shallow junctions in the channel when the TFT is reversely biased. Kink effect can also be eliminated in the output characteristics. As a result, important electrical properties such as the sub-threshold swing, threshold voltage, maximum field effect mobility, leakage current, on-off ratio and device uniformity can all be improved using the present technique. It is considered to be a big break-through technique, which can be easily realized on large size glass substrate and suitable to all the existing LTPS techniques.