光刻胶剥离制程中的寄生栅极效应

Parasitic gate effect in photo-resist strip process

在薄膜晶体管(Thin film transistor,TFT)的公共电极制程中,有部分TFT样品的漏电流(I_(off))异常偏高,该部分样品经历同一个光刻胶剥离设备,导致该设备暂停流片,造成产能损失。明确该剥离设备造成TFT漏电流偏高的原因并予以解决,对产能和品质确保具有积极意义。本文首先收集了异常设备剥离液和正常设备的剥离液并分析成分,发现异常设备的剥离液中Al离子含量高。其次,发现TFT的I_(off)会随着在异常设备流片次数的增加而上升。其原因是Al离子在剥离制程生成Al_(2)O_(3)颗粒,该颗粒附着在TFT器件钝化层上形成寄生栅极效应,最终造成I_(off)增加。最后,结合TRIZ输出解决方案,并优选方案进行改善验证。实验结果表明,剥离液中的Al离子浓度由1×10^(-8)上升到2.189×10^(-6)时,I_(off)由3.56 pA上升到7.56 pA。当剥离液中含有Al离子,经历的剥离次数增加时,I_(off)呈上升趋势。钝化层成膜前的等离子体处理功率增强、钝化层膜厚增加可以抑制I_(off)增加。由此,可以确定剥离设备造成I_(off)偏高的原因是剥离液中的Al离子形成的寄生栅极效应,钝化层成膜前处理强化和膜厚增加均可以抑制该效应。

In the common ITO manufacturing process of TFT(Thin Film Transistor),the leakage current(I_(off))of some samples is abnormally high,and these abnormal samples are subjected to the same photo-resist strip equipment.This anomaly causes the strip equipment to suspend production,resulting in a loss of mass production.It is urgent to identify the reason and solve this problem for productivity and quality assurance.Firstly,the stripper of abnormal and normal equipment are collected and analyzed,it is found that the Al ion content in the stripper corresponding to the abnormal equipment was high.Secondly,it is found that Iwill increase with the increase of stripping time in abnormal equipment.Then,it is proposed that Al ions in stripper are converted into Al_(2)O_(3)particles adhered to the passivation(PVX)layer of TFT device during the stripping process,forming a parasitic gate effect which causes I_(off)to be high.Finally,a series of solutions are proposed based on TRIZ,and then verified.Experimenta results show that the Al ion concentration in the stripper increases from 1×10^(-8)to 2.189×10^(-6),and the I_(off)increases from 3.56 p A to 7.56 p A.Once the stripper contains Al ions,Iincreases as the number of stripping increases.The increase of I_(off)can be suppressed by two measures:enhancement of the plasma treatment power before the PVX depositon and the increase of PVX thickness.In summary,it can be determined that the abnormally high I_(off)is caused by the parasitic gate effect formed by Al ion in stripper solution,which can be suppressed by strengthening plasma treatment before PVX deposition and the increase PVX thickness.