Research progress of wafer cleaning and selective etching in supercritical carbon dioxide media
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.
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