Polymethyl methacrylate (PMMA) has been widely applied in the semiconductor field due to its excellent specialties of transparency and durability, but impurities in the polymerization process result in electric leakage and are tough to remove even during high-temperature baking. In this study, a near-room-temperature supercritical CO₂ fluid (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 fluid at near-room-temperature to enhance the electric characteristics. An Al/PMMA/Mo metal–insulator–metal device is fabricated to investigate the improvement in PMMA quality. The leakage current of the device can be decreased more than 10-fold and its capacitance can also become more stable after NRT-SCF treatment. The current conduction mechanism is transformed from Hopping conduction to Schottky emission. Fourier transform infrared spectroscopy test results confirmed that defects like butyl acetate and benzoyl peroxide in PMMA films have been reduced a lot based on material analysis. The findings of this study lead to the hopeful prospect that supercritical CO₂ fluid technology can greatly promote the insulating properties of PMMA and offer more potential applications for PMMA in wider fields.

中文翻译：

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一种超临界去除方法：在室温附近快速去除聚甲基丙烯酸甲酯中的杂质和提高绝缘性能的机理研究

聚甲基丙烯酸甲酯（PMMA）由于其优异的透明性和耐久性而在半导体领域得到了广泛应用，但是聚合过程中的杂质会导致漏电，即使在高温烘烤过程中也很难去除。在这项研究中，采用近室温超临界CO ₂流体（NRT-SCF）处理方法来纯化PMMA，并改善其绝缘性能。超临界CO ₂可以轻松去除PMMA膜中的残留溶剂和引发剂在接近室温的流体中增强电特性。制造了一种Al / PMMA / Mo金属-绝缘体-金属器件以研究PMMA质量的提高。经过NRT-SCF处理后，器件的泄漏电流可以降低10倍以上，并且其电容也可以变得更加稳定。电流传导机制从跳跃传导转变为肖特基发射。傅里叶变换红外光谱测试结果证实，基于材料分析，PMMA膜中的乙酸丁酯和过氧化苯甲酰等缺陷已大大减少。这项研究的发现导致了有希望的前景，那就是超临界CO ₂流体技术可以大大提高PMMA的绝缘性能，并为PMMA在更广阔的领域提供更多的潜在应用。