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相对来讲,i线(i-line)抗酸性要大大强于KrF而不容易产生类似的缺陷,但器件尺寸微缩进入45/40nm技术节点以后,由于受到分辨率(Resolution)和焦深(DepthofFocus)的限制,双栅极(DualGate)蚀刻所用光刻胶由之前通用的i-line(波长365nm)改成KrF(波长248nm)。由于这种缺陷会导致在双栅极氧化层湿法蚀刻后应该被蚀刻去除的栅极氧化层有残留,最终导致核心器件区栅极氧化层厚度不均匀而影响器件的性能。因此,KrF抗酸性研究就成为器件尺寸微缩进入45/40nm技术节点以后的一个课题。本文主要阐述了对双栅极氧化层湿法刻蚀中KrF光刻胶在DHF(DilutedHydrogenFluoride)中浸泡去除清洗过程中出现的隐形残留缺陷问题的发现,并且研究产生这种由于缺乏抗酸性而产生缺陷的机理,进而阐述通过多项基于这种现象和机理的DHF工艺蚀刻时间、光刻胶显影后烘焙硬化处理、UV光照处理、等离子体抗酸处理等实验过程及效果,最终总结出有效的解决方案:基于低温(摄氏90度)、低功率(小于1000W)下的以氧气和氮氢混合气为反应气体的Descum等离子处理非常有效地解决了光刻胶在酸液中形成残留缺陷的问题。
Relatively speaking, the i-line is much more resistant to acid than KrF and is not prone to similar defects. However, as the device size shrinks into the 45 / 40nm technology node, due to the resolution and depth of focus ), The photoresist used for dual-gate etching was changed from KrF (wavelength 248 nm) previously used in i-line (wavelength 365 nm) to KrF (wavelength 248 nm). Because of this defect, the gate oxide that should be etched and removed after the wet etching of the dual gate oxide remains, eventually resulting in uneven gate oxide thickness of the device region and affecting the performance of the device. Therefore, the study of KrF acid resistance has become a topic after the device size is miniaturized into the 45 / 40nm technology node. This paper mainly expounds the discovery of the invisible residue defect in the cleaning process of KrF photoresist dipped in DHF (Diluted Hydrogen Fluoride) in the double-gate oxide wet etching, Defect mechanism, and then elaborated on a number of experiments based on this phenomenon and mechanism of the DHF etching time, photoresist development after baking hardening treatment, UV light treatment, acid treatment of plasma and other experimental process and the effect of the final sum of effective Solution: Descum plasma treatment based on a mixture of oxygen and nitrogen and hydrogen at low temperature (90 ° Celsius) and low power (less than 1000 W) is a very effective solution to the problem of residual defects of photoresist in acid solution .