HADS型TFT基板制程中通常存在两次ITO退火工艺, 而Cell制程中则存在相似的配向膜高温烘焙工艺。为提升TFT产线退火工序的产能, 因此考虑对ITO退火进行时间上的缩减甚至直接省略, 然后利用配向膜烘焙的热处理对前层ITO的结晶进行补偿, 但ITO结晶方式的变化还需确保产品高透过率特性。对比实验的结果表明: 单层ITO退火时间由30 min缩减至10 min时, 产品的透过率基本保持不变; 2nd ITO退火直接省略时产品仍具备高的透过率特性, 但1st ITO退火省略时产品的透过率则会大幅降低, 其主要原因是钝化绝缘层的阻隔导致了1st ITO中的亚氧化物无法被后工段的热处理所氧化, 而配向膜涂覆后的2nd ITO在烘焙过程中仍可以与外界高温空气结合反应。在确保产品高透过率的前提下, 选择从源头上减少了1st ITO内亚氧化物的产生, 通过增加1st ITO成膜时的氧气流量也可以实现1st ITO退火的直接省略。最终两次ITO退火均可被配向膜烘焙所替代且产品兼具高透过率特性, 最大化地提升了TFT产线的生产效率。

This paper makes a research on the relationship of ITO anneal to the transmittance of HADS TFT-LCD, which based on polyimide oven to replace ITO anneal for manufacturing efficiency enhancement. The result shows that 1st ITO and 2nd ITO anneal process with a shorter operation time, for example, 10 min makes the same level of transmittance as the normal case of 30 min. Furthermore, the 2nd ITO anneal skip process can also maintain a high-level transmittance, because the air infiltration through polyimide can oxidate the 2nd ITO well during the oven process. However, the 1st ITO anneal skip process leads to a significant transmittance decrease due to the dense passivation, which prevents the 1st ITO from being oxidated by polyimide oven/2nd ITO anneal. Based on this reason, the oxygen reactant gas during 1st ITO sputtering is increased to produce less suboxide, which has an effect similar to the oxidation of anneal, and thus a high-level transmittance of 1st ITO skip process is observed after polyimide oven. Therefore, 1st ITO anneal can be skipped as well as 2nd ITO anneal, which can greatly improve the manufacturing efficiency.