An amorphous Si TFT array with TaOx/SiNx double layered insulator for liquid crystal displays

An experimental a-Si thin-film transistor (TFT) for liquid-crystal-display applications, with a double layer of reactively sputtered TaO/sub x/ and plasma CVD SiN/sub x/ insulator, is described. In comparison to TFT with SiN/sub x/ (400-nm) single-layered insulator, TFT with TaO/sub x/ (200-nm)/SiN/sub x/ (200-nm) insulator showed mobility increased by 30%, on-current twice as large, and off-current reduced to one half. The sizes of a TFT and a storage capacitor may be reduced by using the double layer with an effective dielectric constant of about 10. TaO/sub x/ layer acts as a projection layer for ITO pixel electrodes during fabrication process. Experimental TFT arrays showed larger operating margin and superior stability.<
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