Abstract:

With the gradual reduction of the feature size of integrated circuits, the device structure will require higher aspect ratios. Due to the surface tension, it is difficult for conventional wet cleaning to enter the deep trench structure of the wafer, which cannot meet the requirements of finer line technology and high aspect ratio. The structure directly affects the pollutant removal effect in the trench. Conventional wet etching methods exhibit poor anisotropy, significant structure collapse, and ineffective etching of deep trenches. On the other hand, plasma dry etching techniques suffer from slow etching rates, photoresist detachment and adhesion, structural damage, and exhaust gas treatment issues. Supercritical cleaning and etching techniques have emerged as the most promising environmentally-friendly and non-damaging alternatives with the ability of integrating etching, cleaning, and drying processes. Moreover, they can be recycled, ensuring safety and environmental sustainability. This review summarizes the progress in wafer cleaning and selective etching using supercritical carbon dioxide, focusing on the applications of supercritical carbon dioxide cosolvent and microemulsion systems in photoresist stripping and selective etching on silicon-based substrates. Finally, the challenges and development trends of wafer cleaning and etching using supercritical carbon dioxide are discussed.

Key words: wafer cleaning, wafer etching, supercritical carbon dioxide, supercritical fluid, microemulsion

摘要：

随着集成电路特征尺寸的逐渐减小，器件结构会要求更高的纵横比，常规湿法清洗由于表面张力很难进入晶圆深沟槽结构内部，不能满足更细线条工艺要求和高深宽比结构，直接影响沟槽内的污染物去除效果；常规湿法刻蚀各向异性差、结构坍塌严重、深沟槽刻蚀效果不明显；而等离子体干法刻蚀则存在刻蚀速率慢、光刻胶脱落和黏附、结构损伤、废气处理等一系列问题。超临界清洗和刻蚀技术是最具有前景的环境友好、无损伤技术，能够耦合刻蚀、清洗与干燥工艺为一体，且可以循环使用，安全环保，是晶圆制造过程中常规清洗和刻蚀的首选替代技术。综述了超临界二氧化碳中晶圆清洗与选择性刻蚀的研究进展，重点介绍了超临界二氧化碳共溶剂、微乳液体系在光刻胶剥离以及含硅基底选择性蚀刻中的应用，展望了超临界二氧化碳晶圆清洗和刻蚀存在的问题和发展趋势。

关键词: 晶圆清洗, 晶圆刻蚀, 超临界二氧化碳, 超临界流体, 微乳液