P‐59: Improving TFT Structure Uniformity in G8.5 LCDs

Methods for lessening the AS tail and N+ tail were systematically investigated in G8.5 glass for LCD product development including novel structure designs and matched 4‐Mask process. While matched 4‐Mask process had success in tails reducing, Ion keeping, stability improving and Ioff decreasing at higher negative voltage by optimized O2 ashing process, further efforts were still indispensable. Novel mask structure designs were provided using photoresist thickness modulation method for 4‐Mask process architecture to ulteriorly reduce the tails. Less amorphous silicon tail (AS tail) and heavy doped amorphous silicon tail (N+ tail) were attained in both inner and outline frame beside the second metal solely by structure design, which limited the scope of N+ tail within 0.5 um and AS tail about 1.2um, respectively. What’s more, the N+ tail could be further decreased by cooperating with the matched 4‐Mask process using the optimized recipe.