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Volume production of 45nm node devices utilizing Nikon's S610C immersion lithography tool has started. Important to the success in achieving high-yields in volume production with immersion lithography has been defectivity reduction. In this study we evaluate several methods of defectivity reduction. The tools used in our defectivity analysis included a dedicated immersion cluster tools consisting of a Nikon S610C, a volume production immersion exposure tool with NA of 1.3, and a resist coater-developer LITHIUS i+ from TEL. In our initial procedure we evaluated defectivity behavior by comparing on a topcoat-less resist process to a conventional topcoat process. Because of its simplicity the topcoatless resist shows lower defect levels than the topcoat process. In a second study we evaluated the defect reduction by introducing the TEL bevel rinse and pre-immersion bevel cleaning techniques. This technique was shown to successfully reduce the defect levels by reducing the particles at the wafer bevel region. For the third defect reduction method, two types of tool cleaning processes are shown. Finally, we discuss the overall defectivity behavior at the 45nm node. To facilitate an understanding of the root cause of the defects, defect source analysis (DSA) was applied to separate the defects into three classes according to the source of defects. DSA analysis revealed that more than 99% of defects relate to material and process, and less than 1% of the defects relate to the exposure tool. Material and process optimization by collaborative work between exposure tool vendors, track vendors and material vendors is a key for success of 45nm node device manufacturing.

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We examined an environmentally friendly photoresist removal method using H radicals produced by decomposing hydrogen on a hot iridium catalyst. We examined the relationship between photoresist removal rate and its surface temperature using thin film interference and the removal properties using H radicals produced by the Ir catalyst. Decomposition behavior at polymer surface by radicals may be analyzed in further detail from the aspect of kinetics. Additionally, we investigated the oxygen addition effects on the removal rate. The photoresist removal rate increased with the oxygen additive amount and then decreased more gradually than in the case of using W filament. The increasing behavior was similar but there was a large difference between W and Ir catalyst in the decreasing behavior.