Bridging the defect gap in EUV photoresist

摘要

Continued momentum in the development of EUV photolithography toward high volume manufacturing has driven theevolution of increased photoresist purity requirements. Further scaling will intensify the challenge to improve inlineyield and reliability performance. The composition of EUV photoresist materials requires careful compositional balanceand stability to ensure expected lithographic performance. It is therefore critical to understand and assess interactionsbetween photomaterials and the many touchpoints along the entire value chain to maintain the purity and integrity ofthese materials.Filtration technology is an important part of maintaining a material’s purity. When choosing a filter, there are manyfactors to consider, starting with the membrane material. For instance, nylon filters effectively remove polar polymersthrough an adsorption mechanism. Particulate contaminants are often removed by size-exclusion, mostly commonlyobserved with certain UPE (ultra-high molecular weight polyethylene) membranes. As lithography materials change andthe smallest defects become even more challenging to detect, filtration technology innovation, such as the developmentof OktolexTM, is needed to meet the most stringent defect targets. In this paper, a tailored filter is introduced to enhancefiltration performance and address specific defect sources in EUV photoresists. Results and possible mechanisms of thedefect reduction will be discussed.