Dr. Yi Yi Profile

Dr. Yi Yi

Research Associate at Cornell Univ

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Publications (4)

Proceedings Article | 1 April 2009 Paper

Reworkable spin-on trilayer materials: optimization of rework process and solutions for manufacturability

Ruzhi Zhang, Allen Timko, John Zook, Yayi Wei, Lyudmila Pylneva, Yi Yi, Chenghong Li, Hengpeng Wu, Dalil Rahman, Douglas McKenzie, Clement Anyadiegwu, Ping-Hung Lu, Mark Neisser, Ralph Dammel, Ron Bradbury, Timothy Lee

Proceedings Volume 7273, 72732O (2009) https://doi.org/10.1117/12.814708

KEYWORDS: Semiconducting wafers, Silicon, Coating, Inspection, Manufacturing, Chemistry, Fourier transforms, Defect inspection, Polymers, Photoresist materials

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Trilayer stacks with alternating etch selectivity were developed and extensively investigated for high NA immersion lithography at 32nm node and beyond. The conveyance of pattern transfer function from photoresist to Si-containing bottom anti-reflective coating (Si-BARC) and carbonrich underlayer hard-mask (UL) elegantly solved the small etch budget issue for ultra-thin photoresists in immersion lithography. However, due to the hybrid nature of Si-BARC, many different behaviors were observed in comparison to conventional BARC. Lithographic performance, stability, and reworkability were among the most challenging issues for trilayer scheme. Despite of the rapid improvement in lithographic performance and stability of trilayer materials reported by several papers, the rework and cleaning of trilayer materials by wet chemistry remained a challenging problem for manufacturability. The dual function requirement of reflection control and pattern transfer (i.e. hard-masking) for spin-on Si-BARC mandates hybrid materials. Si-BARC containing both organic moiety and inorganic backbone were extensively studied and demonstrated excellent performance. However, the hybrid nature of Si-BARC necessitates the revisit of different wet chemistries and process adjustment is essential to achieve desirable results. In addition, the similarity in chemical structures between Si-BARC and low-κ dielectrics demands subtle rework differentiation by wet chemistry from a chemistry point of view. In our development, we strived to identify rework solutions for trilayer materials in both front-end-of-line (FEOL) and back-end-of-line (BEOL) applications. Rework solutions including diluted HF, Piranha, and low-κ compatible strippers were extensively investigated. The optimization of solution mixture ratios and processing conditions was systematically studied. Thorough defect inspection after rework was performed to ensure the readiness for manufacturability. Extensive Piranha rework study on stack wafers and monitor wafers were carried out and excellent results are reported.

Proceedings Article | 26 March 2008 Paper

Ionic photo-acid generators containing functionalized semifluorinated sulfonates for high-resolution lithography

Yi Yi, Ramakrishnan Ayothi, Christopher Ober, Wang Yueh, Heidi Cao

Proceedings Volume 6923, 69231B (2008) https://doi.org/10.1117/12.772880

KEYWORDS: Polymers, Lithography, Extreme ultraviolet lithography, Diffusion, Line edge roughness, Absorption, Extreme ultraviolet, Electron beam lithography, Transparency, Photoresist materials

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Proceedings Article | 26 March 2008 Paper

New architectures for high resolution patterning

Anuja De Silva, Nelson Felix, Drew Forman, Jing Sha, Christopher Ober

Proceedings Volume 6923, 69230O (2008) https://doi.org/10.1117/12.772667

KEYWORDS: Magnesium, Glasses, Polymers, Line edge roughness, Molecules, Extreme ultraviolet lithography, Photoresist materials, Optical lithography, Lithography, Photoresist developing

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Proceedings Article | 29 March 2006 Paper

All-organic non-PFOS nonionic photoacid generating compounds with functionalized fluoroorganic sulfonate motif for chemically amplified resists

Ramakrishnan Ayothi, Yi Yi, Christopher Ober, Steve Putna, Wang Yueh, Heidi Cao

Proceedings Volume 6153, 61530J (2006) https://doi.org/10.1117/12.656500

KEYWORDS: Lithography, Line edge roughness, Electron beam lithography, Chromophores, Carbon, Fluorine, Absorption, Polymers, Scanning electron microscopy, Chemically amplified resists

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