In the photolithography process of integrated circuits （IC） manufacturing, it is desired that the photoresist resins have both smaller polydispersity index (PDI) and lower trace metal ion concentrations. The commercial environmentally stable chemical amplified photoresist (ESCAP) resins for 248 nm lithography are synthesized by free radical polymerization with PDI >1.5. Although using atom transfer radical polymerization (ATRP) can result in lower PDI, the potential of high metal ion contamination is a major concern, as the reaction initiators usually are copper-containing compounds. In this study, copolymer of p-acetoxy styrene and tert-butyl acrylate [poly(AOST-co-TBA)] is synthesized via ATRP achieving PDI as low as 1.25. It is then purified by ion exchange with two different resins, IRC747 and A15, which are effective at removing Cu and other metal ions. This reduces the total metal ion concentration in the copolymer powder to <30 ppb with individual metal ion <6 ppb. This is the first reported ATRP synthesized ESCAP resin having both low PDI and metal ion concentrations suitable for 248 nm photoresist application.

中文翻译：

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通过原子转移自由基聚合合成的 ESCAP 树脂中的总金属离子浓度低于 100 ppb

在集成电路（IC）制造的光刻工艺中，要求光刻胶树脂既具有较小的多分散指数（PDI），又具有较低的痕量金属离子浓度。用于 248 nm 光刻的商业环境稳定的化学放大光刻胶 (ESCAP) 树脂是通过自由基聚合合成的，PDI > 1.5。虽然使用原子转移自由基聚合 (ATRP) 可以降低 PDI，但高金属离子污染的可能性是一个主要问题，因为反应引发剂通常是含铜化合物。在本研究中，通过 ATRP 合成了对乙酰氧基苯乙烯和丙烯酸叔丁酯的共聚物[ poly ( AOST- co -TBA)]，PDI 低至 1.25。然后通过两种不同的树脂 IRC747 和 A15 进行离子交换进行纯化，这两种树脂可有效去除铜和其他金属离子。这将共聚物粉末中的总金属离子浓度降低至<30 ppb，其中单个金属离子<6 ppb。这是第一个报道的 ATRP 合成 ESCAP 树脂，具有低 PDI 和金属离子浓度，适合 248 nm 光刻胶应用。