高可靠性Cu BCE a-IGZO TFTs的制作

背沟道刻蚀型（BCE）非晶氧化铟镓锌薄膜晶体管（a-IGZO TFT）具有工艺简单、寄生电容小以及开口率高等优点，但BCE IGZO器件背沟道易受酸液和等离子体损伤，进而引起TFT均匀性和稳定性等方面问题，随着GOA技术的导入，对TFT器件电学性能的均匀性和稳定性提升的要求也日益迫切，因此开发高信赖性BCE IGZO TFT是技术和市场的迫切要求。本文主要分析了基于IGZO的背沟道刻蚀型薄膜晶体管电学性质，通过优化钝化层材料，色阻材料以及GOA TFT结构等削弱因背沟道水汽吸附引起的器件劣化，偏压温度应力测试结果显示优化后的TFT展现了良好的稳定性——在80℃，栅极30 V负向偏压条件下，2 000 s的ΔV_th小于1 V。最终，利用优化的IGZO TFT制作了215.9 mm（85 in）8K4K 120 Hz液晶显示器。

Fabrication of high-reliability Cu BCE-structure IGZO TFTs

Back channel etched (BCE) amorphous InGaZnO (a-IGZO) can be fabricated with fewer photolithography masks and achieve smaller parasitic capacitance. However, the back channel of the BCE a-IGZO TFT is vulnerable to acid and plasma damage, which leads to problems of TFT uniformity and stability. In particular, with the introduction of gate driver on array (GOA) technology, it is increasingly urgent to improve the electrical uniformity and stability of TFTs. Therefore, it is an urgent requirement for technology and market to develop high reliability BCE IGZO TFTs. The electrical characteristic of the BCE configuration based a-IGZO TFTs were studied. The passivation layer, the selection of color filter material and design of GOA TFT structure were modified for lessening the influence of H₂O molecules adsorbing on the back channel of the BCE-structure. The negative and positive bias temperature stress(N/PBTS) results revealed that the optimized GOA TFTs exhibited good device reliability-the V_th shift under gate voltage of -30 V at 80℃ is less than 1 V for 2 000 s. Finally, a high performance 215.9 mm(85 in) 8K4K 120 Hz GOA LCD was demonstrated.