1988 INTERNATIONAL DISPLAY RESEARCH CONFERENCE AN AMORPHOUS Si TFT ARRAY WITH TaOx/SiNx DOUBLE LAYERED INSULATOR FOR LIQUID CRYSTAL DISPLAYS

An experimental a-Si TFT, designed for LCD applications, with double layer of reactively-sputtered TaOx and plasma CVD SiNx insulator is described. In comparison to TFT with SiNx (400nm) single-layered insulator, TFT with TaOx(ZOOnm)/SiNx(ZOOnm) 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. TaOx layer acts as a protection layer for IT0 pixel electrodes during fabrication process. Experimental TFT arrays showed larger operating margin and superior stability.