Supercritical Removal Method: Rapid Elimination of Impurities in Polymethyl-methacrylate at Near Room Temperature and Mechanism Investigation of Insulating Property Improvement

Polymethyl methacrylate (PMMA) has been widely applied in semiconductor fields due to its excellent transparent and durable specialty, but impurities in polymerization process result in electric leakage and are tough to remove even at high-temperature baking. In this study, a near-room-temperature supercritical CO2 fluids (NRT-SCF) treatment method is adopted to purify PMMA and improve its insulating properties. Residual solvent and initiators in PMMA films can be easily taken away by supercritical CO2 fluids at near room temperature to enhance its electric characteristics. Al/PMMA/Mo metal-insulator-mental device are fabricated to investigate the improvement of PMMA’s quality. The leakage current of the device can be decreased by more than 10 times and its capacitance also becomes more stable after NRT-SCF treatment. Current conduction mechanism has transformed from Hopping conduction to Schottky emission. Fourier transform infrared spectroscopy test results have confirmed that defects like Butyl acetate and Benzoyl peroxide in PMMA films have been reduced a lot in terms of material analysis. The findings in this study show a hopeful perspective that supercritical CO2 fluids technology can greatly promote the insulating property of PMMA and offer PMMA more potential application in wider fields.