Nitroxide mediated polymerization for narrow molecular weight distribution copolymers: application to photoresist materials

为了压印用于微电子学的亚微米特征，使用光刻法来蚀刻对辐射敏感的聚合物（例如，光致抗蚀剂）。曝光后，由于溶解度的变化，通过化学处理从光致抗蚀剂显影图案。 决定特征尺寸的因素如线宽分辨率（LWR）取决于所用聚合物的类型和聚合物的性质。通常，使用两种或更多种单体的常规自由基聚合来制备用于光致抗蚀剂的所需共聚物。 然而，这样的聚合方法不能很好地控制链结构，这对于LWR是至关重要的。 受控自由基聚合（CRP）基本上使用自由基化学，但可以非常严格地控制分子量分布和微观结构。 一些CRP方法（例如，RAFT、ATRP）已经应用于光致抗蚀剂材料，但主要缺点是它们缺乏透明度，并且它们需要除去催化剂和链转移剂。 我们的目标是应用CRP的另一种变体，称为NMP，它不会使聚合物变色，但仍然提供受控的微观结构。 然而，NMP尚未应用于光致抗蚀剂。我们的项目将首先评估NMP化学作为光致抗蚀剂聚合物的路线，可能用于193 nm光致抗蚀剂与圣让光化学公司。（SJPC）作为工业赞助商。 SJPC将为微电子行业的利基材料提供聚合化学和放大设施方面的专业知识。

To imprint sub-micron features for microelectronics, photolithography is used to etch the desired pattern with polymers that are sensitive to the irradiation (eg. photoresists). After exposure, patterns are developed by chemical treatment from the photoresists due to solubility changes. Factors such as line width resolution (LWR) that determine feature size depend on the type of polymer used and the properties of the polymer. Typically, conventional free radical polymerization of two or more monomers is used to make the desired copolymer for the photoresist. However, such a polymerization method does not control chain structure well, which is critical for LWR. Controlled radical polymerization (CRP) uses essentially free radical chemistry but can control molecular weight distribution and microstructure very tightly. Some CRP methods (eg. RAFT, ATRP) have been applied for photoresist materials but the major disadvantage is their lack of transparency and they require catalyst and chain transfer agent removal. We aim to apply another variant of CRP termed NMP, which does not leave polymers discoloured but still provides controlled microstructure. NMP has however not been applied towards photoresists. Our project will first evaluate NMP chemistry as a route towards photoresist polymer potentially for 193 nm photoresists with St-Jean Photochemicals Inc. (SJPC) as the industrial sponsor. SJPC will provide their expertise in polymerization chemistry and scale-up facilities for niche materials in the microelectronics industry.