As future patterning processes reach the limit of lithographic printability, continuous innovation in mandrel trim or shrink strategies are required to reach sub-20 nm line-space patterning. Growing concerns of lithography defectivity, mask selectivity, line edge roughness (LER), line width roughness (LWR), and critical dimension uniformity (CDU) present significant challenges towards this goal. The authors compare various alternative mandrel trim strategies to highlight potential solutions and drawbacks towards enabling successful printing of mandrels used in extreme ultraviolet (EUV) multi-patterning schemes. Through this comparison, the authors demonstrate the challenges of maintaining adequate pattern transferability while keeping aspect ratio-driven line roughness and material selectivity under control. By process partitioning, the limitations of traditional lithography and etch trimming strategies are highlighted, suggesting the need for new methods of CD reduction after the pattern has been transferred. These new trimming methods offer flexibility in CD control without negatively impacting the mandrel profile and demonstrates better tunability across different material sets, allowing for evaluation of different mask and mandrel material combinations for downstream process optimization.
Extreme ultraviolet lithography (EUVL) technology is one of the leading candidates under consideration for enabling the next generation of devices, for 7nm node and beyond. As the focus shifts to driving down the 'effective' k1 factor and enabling the second generation of EUV patterning, new techniques and methods must be developed to reduce the overall defectivity, mitigate pattern collapse, and eliminate film-related defects. A typical defect Pareto for EUV line-space patterning is dominated by bridging defects and pattern collapse. Regarding pattern collapse, careful attention needs to be paid to optimizing the rinse process to avoid the large forces that cause collapse during drying. In this paper, we present an optimized rinse technology that works to prevent that pattern collapse, especially on EUV line/space patterns below 40nm pitch. Additionally, this paper reviews the ongoing progress in track-based processes (coating, developer) that are required to enable EUV patterning. This work is especially focused on defect mitigation during film coating and resist developing processes, which have a direct effect on the occurrence of bridging defects during pattern transfer.
Extreme ultraviolet lithography (EUVL) technology is one of the leading candidates under consideration for enabling the next generation of devices, for 7nm node and beyond. As the focus shifts to driving down the 'effective' k1 factor and enabling the second generation of EUV patterning, new techniques and methods must be developed to reduce the overall defectivity, mitigate pattern collapse, and eliminate film-related defects. In addition, CD uniformity improvements must be continued to meet patterning performance requirements. Tokyo Electron Limited (TELTM) and IBM Corporation are continuously developing manufacturing quality processes for EUV.
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