Dr. Ramasamy Raju Profile

Dr. Ramasamy Raju

Postdoctoral Research Associate at Univ of Illinois

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Publications (9)

Proceedings Article | 1 April 2009 Paper

Reducing LER using a grazing incidence ion beam

C. R. M. Struck, R. Raju, M. J Neumann, D. N. Ruzic

Proceedings Volume 7273, 727346 (2009) https://doi.org/10.1117/12.814263

KEYWORDS: Line width roughness, Line edge roughness, Photoresist materials, Ions, Ion beams, Sputter deposition, Scanning electron microscopy, Image processing, Argon, Semiconductors

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Proceedings Article | 18 March 2009 Paper

Removal of contaminants by plasma assisted cleaning by metastable atom neutralization (PACMAN)

W. Lytle, D. Szybilski, C. Das, R. Raju, D. Ruzic

Proceedings Volume 7271, 72713C (2009) https://doi.org/10.1117/12.813184

KEYWORDS: Plasma, Particles, Helium, Silicon, Semiconducting wafers, Photomasks, Contamination, Carbon, Chemical species, Extreme ultraviolet lithography

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Proceedings Article | 18 March 2009 Paper

Measurement of particle flux at the intermediate focus of a DPP source

J. Sporre, R. Raju, D. Ruzic, V. Surla, F. Goodwin

Proceedings Volume 7271, 727137 (2009) https://doi.org/10.1117/12.814225

KEYWORDS: Ions, Sensors, Particles, Contamination, Extreme ultraviolet, Silicon, Carbon, Plasma, Silicon carbide, Oxygen

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Proceedings Article | 18 March 2009 Paper

Remote plasma cleaning of Sn from an EUV collector mirror

H. Shin, R. Raju, D. Ruzic

Proceedings Volume 7271, 727131 (2009) https://doi.org/10.1117/12.813353

KEYWORDS: Plasma, Chlorine, Tin, Reflectivity, Extreme ultraviolet, Contamination, Plasma systems, Chlorine gas, Photodiodes, Mirrors

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Proceedings Article | 4 December 2008 Paper

Grazing incidence ion beams for reducing LER

C. Struck, M. Neumann, R. Raju, R. Bristol, D. Ruzic

Proceedings Volume 7140, 71402P (2008) https://doi.org/10.1117/12.804692

KEYWORDS: Line edge roughness, Photoresist materials, Line width roughness, Scanning electron microscopy, Ions, Argon, Ion beams, Grazing incidence, Semiconductors, Sputter deposition

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Proceedings Article | 4 December 2008 Paper

Removal of particles from lithographic masks through plasma-assisted cleaning by metastable atomic neutralization

W. Lytle, D. Szybilski, C. Das, R. Raju, V. Surla, M. Neumann, D. Ruzic

Proceedings Volume 7140, 71401S (2008) https://doi.org/10.1117/12.804704

KEYWORDS: Plasma, Particles, Helium, Semiconducting wafers, Photomasks, Atmospheric particles, Silicon, Lithography, Chemical species, Extreme ultraviolet lithography

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Proceedings Article | 4 December 2008 Paper

EUVL contamination control studies for high-volume manufacturing

D. Ruzic, R. Raju, J. Sporre, H. Shin, W. Lytle, M. Neumann

Proceedings Volume 7140, 714006 (2008) https://doi.org/10.1117/12.804689

KEYWORDS: Particles, Contamination, Ions, Line edge roughness, Extreme ultraviolet, Tin, Plasma, Extreme ultraviolet lithography, Mirrors, Silicon

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Proceedings Article | 9 April 2008 Paper

Plasma cleaning of nanoparticles from EUV mask materials by electrostatics

W. Lytle, R. Raju, H. Shin, C. Das, M. Neumann, D. Ruzic

Proceedings Volume 6922, 69220D (2008) https://doi.org/10.1117/12.772363

KEYWORDS: Particles, Plasma, Electrons, Photomasks, Contamination, Semiconducting wafers, Dielectrics, Extreme ultraviolet, Silicon, Ruthenium

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Proceedings Article | 21 March 2008 Paper

Plasma Sn cleaning integrated in EUV source system

H. Shin, R. Raju, D. Ruzic

Proceedings Volume 6921, 692132 (2008) https://doi.org/10.1117/12.772090

KEYWORDS: Tin, Plasma, Extreme ultraviolet, Mirrors, Ruthenium, Extreme ultraviolet lithography, Chlorine, Etching, Ions, Xenon

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Extreme ultraviolet lithography (EUVL) is a potential candidate for the next generation lithography techniques, which will use Xe or Sn as a main fuel to produce EUV light. However, the industry has favored to use Sn as main fuel in EUVL systems because of its high conversion efficiency over Xe. Sn has an advantage of producing more light, but on the other hand its condensable nature is a real threat to the reflective mirrors which are used to collect the EUV light at intermediate focus. Center for Plasma Material Interactions (CPMI) at the University of Illinois has studied plasma etching as a potential method of Sn removal from collector optics. RF-driven chlorine plasma is used to etch Sn from mirror samples. Previously we reported high selectivity of Sn over several EUV compatible mirror materials. The increased confidence in this technology had led us to perform cleaning experiments on real Sn contaminated samples exposed in an EUV source and the results obtained have been very encouraging. Small mock up shells (same as in the grazing incidence collector optics system) were constructed at CPMI and chlorine etching was performed at different samples placed at different locations on multi-shell collector mock up in ICP-RIE chamber. Post cleaning material characterization results of samples shows that chlorine can potentially clean Sn off of collector optics (Ru was used in this study as a mirror sample). Realizing this as a viable cleaning solution, we have stepped further and performed a full size cleaning test in the Xtreme's XTS 13-35 EUV source. Large mock up with appropriate dimension was placed in the EUV source chamber and the cleaning system was installed to etch Sn away from Ru surface. This study compares the cleaning results in a real system scale with the previous simulated system. The comparison shows how to improve the Sn cleaning system in the EUV source chamber. Results are encouraging and may enable source suppliers to integrate this technology in their respective sources. Cleaning rate was measured as >100nm/min using ion sputtered Sn samples.

Showing 5 of 9 publications

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