NER: Supercritical Carbon Dioxide Extraction Process for Forming Nanoporous Materials for Low-k and Biosensor Applications

具有可控纳米孔结构的材料将在微电子和生物传感器领域具有潜在的应用前景。目标是将纳米模板方法与超临界CO2萃取其中一相结合，以创建纳米相分离材料。所提出的方法在目前技术状态上的进步包括可以使用的基质材料类型的灵活性增加，以及比通过热降解从基质中去除多孔物质的方法的加工优势。所提出的工作的科学挑战在于了解与提取CO2可溶性成分而不破坏基质相关的聚合物物理。本质上，这与玻璃化转变、塑化效应、基体的粘弹性和萃取产生的应力有关。我们将在德克萨斯理工大学准备自旋膜，并与IBM的合作者合作，准备纳米相分离的形态。薄膜将包含一种不溶于超临界二氧化碳的成分，也将包含一种可提取的可溶性成分。将对超临界CO2萃取前后薄膜的特性进行表征，包括介电特性、厚度和折射率的测量。此外，薄膜将通过傅里叶变换红外光谱，透射电子显微镜和原子力显微镜进行研究。两名研究生和一名本科生研究员将在pi的直接监督下进行研究。

Materials with controlled nanoporous structures will be developed for potential applications in the areas of microelectronics and biosensors. The goal is to couple a nanotemplating methodology for creating nanophase separated materials with supercritical CO2 extraction of one of the phases. The advancement of the proposed methodology over the current state of the art includes increased flexibility in the types of matrix materials which can be used, as well as processing advantages over methods in which the porogen is removed from the matrix by thermal degradation. The scientific challenge of the proposed work lies in understanding the polymer physics associated with extraction of the CO2 soluble component without collapse of the matrix. In essence, this is related to the glass transition, plasticization effects, the viscoelastic properties of the matrix and the stresses incurred due to extraction. We will prepare spin-on films at Texas Tech, as well as working with collaborators at IBM, to prepare nanophase separated morphologies. The films will contain a component which is insoluble in supercritical CO2 and will also contain a soluble component which can be extracted. Characterization of the properties of the films before and after exposure to supercritical CO2 extraction will be performed, including measurement of the dielectric properties, thickness and refractive index. In addition, films will be studied by Fourier transform infrared spectrometry, transmission electron microscopy and atomic force microscopy. Two graduate students and one undergraduate researcher will perform the research under the direct supervision of the PIs.