Thursday, August 24, 2023

An Update on Directed Self-Assembly (DSA) for Advancing Micro and Nano Fabrication

Revolutionizing fabrication, Directed Self-Assembly (DSA) innovates micro to nano devices and materials. It leverages block co-polymer morphology for precise patterns and guides micro/nano particles, enhancing manufacturing. In semiconductors, DSA addresses lithography challenges, while Imec's research showcases DSA-EUV synergy for defect-free outcomes. Complex rectification processes, illustrated by Imec, spotlight improved Critical Dimension Uniformity and Pattern Placement Error control. As DSA advances, its collaboration with EUV promises precision, efficiency, and innovation across industries.

DSA has emerged as a groundbreaking technique for mass-producing micro to nano devices and materials with precision and efficiency. This method harnesses the inherent properties of materials to assemble them into intricate structures, revolutionizing manufacturing processes across various industries.

DSA leverages block co-polymer morphology to create patterns, enhancing feature control and shape accuracy. This involves guiding the assembly of micro and nano particles to achieve desired structures, made possible by the precise control of surface interactions and polymer thermodynamics. The key advantage of DSA is its ability to create structures at remarkably small scales, enabling advancements in diverse fields.

In the semiconductor industry, DSA offers a new perspective on lithography challenges. Despite initial setbacks, DSA is being revisited to address critical issues such as stochastic defects in extreme ultraviolet (EUV) lithography. These defects, which can contribute significantly to patterning errors, have led semiconductor manufacturers to explore DSA as a solution to rectify these problems. Notably, DSA is not replacing traditional methods but rather enhancing them. It is being integrated with existing manufacturing processes to enable increased resolution and precision, all while reducing costs.

However, challenges persist in integrating DSA into high-volume manufacturing. Defect control remains a primary concern, as the technology strives to meet industry standards of minimal defectivity. Common defects include line bridging, collapse, bubbles, and dislocations. Efforts are ongoing to optimize annealing temperature, etching methods, and film thickness to reduce these defects. Another challenge is the complexity of pattern inspection, which demands accurate metrology methods. Researchers are exploring machine learning-based approaches to automate the inspection process and achieve higher throughput.

Despite these challenges, DSA is being applied to various applications beyond semiconductors. Tissue engineering benefits from the precision of directed assembly, enabling the controlled organization of cells into desired micro-structures. In nanotechnology, DSA facilitates the creation of precise nanostructures, leading to advancements in areas such as graphene nanoribbon arrays and thin-film quantum materials.

Revolutionizing EUV Lithography with Directed Self-Assembly (DSA)

EUV lithography has revolutionized semiconductor manufacturing but comes with its share of challenges, particularly in addressing line roughness and stochastic defects. DSA has now gained attention as a potential game-changer to tackle these issues in EUV lithography.

Recent research from Imec sheds light on the promising synergy between EUV and DSA in overcoming lithography challenges. In the study titled "EUV Lithography Line Space Pattern Rectification Using Block Copolymer Directed Self-Assembly: A Roughness and Defectivity Study," led by Julie Van Bel and team, the researchers explored the combination of DSA with EUV. Their findings indicate that this integration surpasses DSA processes based on Immersion lithography, offering lower line width roughness and freedom from dislocation defects.

Another study, "Mitigating Stochastics in EUV Lithography by Directed Self-Assembly," led by Lander Verstraete and collaborators, delved into the application of DSA to mitigate stochastic defects in EUV processing.

Imec's approach to rectify defects in EUV lithography involves intricate processes, as illustrated in Figures below. In the top Figure, the team outlines the process for rectifying defects in EUV Line/Space Patterns using DSA. Meanwhile, the lower Figure details the rectification process for defects in EUV Contact Patterns.

Imec's approach to rectify defects in EUV lithography involves intricate processes, as illustrated in the figures below. In the top figure, the team outlines the process for rectifying defects in EUV Line/Space Patterns using Directed Self-Assembly (DSA). Meanwhile, the lower figure details the rectification process for defects in EUV Contact Patterns. These illustrations highlight the potential of DSA in enhancing lithographic precision, addressing challenges related to line roughness and stochastic defects, and achieving improved Local Critical Dimension Uniformity (LCDU) and Pattern Placement Error control in semiconductor manufacturing.

The results are particularly promising for line/spaces at a 28nm pitch, primarily addressing bridge defects. However, at a 24nm pitch, further improvement is necessary due to an excess of bridge defects. Notably, the type and frequency of defects correlate with the formulation of the block copolymer and the duration of the annealing process.

For contact arrays, the combination of EUV and DSA demonstrates improved Local Critical Dimension Uniformity (LCDU) and Pattern Placement Error. This advancement also enables the use of a lower dose, contributing to enhanced precision and efficiency in semiconductor manufacturing.

Imec's research underscores the potential of DSA to revolutionize EUV lithography by addressing line roughness and stochastic defects. The successful integration of EUV and DSA holds the promise of enhancing semiconductor manufacturing processes, achieving higher precision, and enabling the production of advanced devices with improved quality. As researchers continue to refine these methods, the collaboration between EUV and DSA is set to shape the future of lithography and microfabrication.

In conclusion, DSA is revitalizing micro and nano fabrication by offering accurate and efficient methods for mass production. While challenges like defect control and metrology persist, DSA's potential to shape the future of industries such as semiconductors, biomedicine, and nanotechnology is undeniable. As research continues to refine DSA processes and overcome hurdles, its role in advancing technology and innovation is set to expand further.

Directed Self-Assembly Finds Its Footing (

SPIE 2023 – imec Preparing for High-NA EUV - SemiWiki

Directed assembly of micro- and nano-structures - Wikipedia

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