Dr. Todd R. Younkin Profile

Dr. Todd R. Younkin

CEO at Semiconductor Research Corp

SPIE Involvement:

Author | Editor

Publications (41)

Proceedings Article | 10 April 2024 Open Access

SRC's Microelectronics and Advanced Packaging Technologies (MAPT) roadmap: an era of innovation driven by energy, workforce, and environmental sustainability

Todd Younkin

Proceedings Volume PC12953, PC1295301 (2024) https://doi.org/10.1117/12.3027041

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Proceedings Article | 20 March 2015 Paper

Material readiness for generation 2 directed self-assembly (DSA) < 24nm pitch

Eungnak Han, Todd Younkin, Manish Chandhok, Alan Myers, Tristan Tronic, Florian Gstrein, Kranthi Elineni, Ashish Gaikwad, Paul Nyhus, Praveen Setu, Charles Wallace

Proceedings Volume 9425, 94250O (2015) https://doi.org/10.1117/12.2086094

KEYWORDS: Etching, Photoresist developing, Wet etching, Scanning electron microscopy, Polymethylmethacrylate, Annealing, Dry etching, Photoresist materials, Picosecond phenomena, Directed self assembly

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Proceedings Article | 17 April 2014 Paper

Investigation of novel inorganic resist materials for EUV lithography

Marie Krysak, James Blackwell, Steve Putna, Michael Leeson, Todd Younkin, Shane Harlson, Kent Frasure, Florian Gstrein

Proceedings Volume 9048, 904805 (2014) https://doi.org/10.1117/12.2046677

KEYWORDS: Extreme ultraviolet lithography, Nanoparticles, Extreme ultraviolet, Optical lithography, Metals, Spectroscopy, FT-IR spectroscopy, Scanning electron microscopy, Ultraviolet radiation, Particles

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Proceedings Article | 28 March 2014 Paper

Evaluation of integration schemes for contact-hole grapho-epitaxy DSA: a study of substrate and template affinity control

A. Romo-Negreira, T. Younkin, R. Gronheid, S. Demuynck, N. Vandenbroeck, T. Seo, D. Guerrero, D. Parnell, M. Muramatsu, S. Kawakami, T. Yamauchi, K. Nafus, M. Somervell

Proceedings Volume 9049, 90491L (2014) https://doi.org/10.1117/12.2046119

KEYWORDS: Etching, Semiconducting wafers, Chemical vapor deposition, Polymers, Fourier transforms, Polymethylmethacrylate, Lithography, Resistance, Picosecond phenomena, Directed self assembly

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Proceedings Article | 1 April 2013 Paper

Roughness and variability in EUV lithography: Who is to blame? (part 1)

Alessandro Vaglio Pret, Roel Gronheid, Todd Younkin, Gustaf Winroth, John Biafore, Yusuke Anno, Kenji Hoshiko, Vassilios Constantoudis

Proceedings Volume 8679, 86792O (2013) https://doi.org/10.1117/12.2011584

KEYWORDS: Photomasks, Extreme ultraviolet lithography, Scanners, Stochastic processes, Nanoimprint lithography, Lithography, Metrology, Photoresist processing, Computer simulations, Extreme ultraviolet

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Proceedings Article | 29 March 2013 Paper

Rectification of EUV-patterned contact holes using directed self-assembly

Roel Gronheid, Arjun Singh, Todd Younkin, Paulina Rincon Delgadillo, Paul Nealey, Boon Teik Chan, Kathleen Nafus, Ainhoa Romo Negreira, Mark Somervell

Proceedings Volume 8682, 86820A (2013) https://doi.org/10.1117/12.2012667

KEYWORDS: Extreme ultraviolet, Extreme ultraviolet lithography, Polymethylmethacrylate, Optical lithography, Critical dimension metrology, Photoresist processing, Image processing, Neodymium, Scanning electron microscopy, Directed self assembly

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Proceedings Article | 29 March 2013 Paper

Progress in directed self-assembly hole shrink applications

Todd Younkin, Roel Gronheid, Paulina Rincon Delgadillo, Boon Teik Chan, Nadia Vandenbroeck, Steven Demuynck, Ainhoa Romo-Negreira, Doni Parnell, Kathleen Nafus, Shigeru Tahara, Mark Somervell

Proceedings Volume 8682, 86820L (2013) https://doi.org/10.1117/12.2012353

KEYWORDS: Etching, Semiconducting wafers, Polymers, Polymethylmethacrylate, Lithography, Wet etching, Dry etching, Chemical vapor deposition, Scanning electron microscopy, Directed self assembly

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SPIE Journal Paper | 12 July 2012

Critical material properties for pattern collapse mitigation

Gustaf Winroth, Roel Gronheid, Todd Younkin, James Blackwell

JM3, Vol. 11, Issue 3, 033004, (July 2012) https://doi.org/10.1117/12.10.1117/1.JMM.11.3.033004

KEYWORDS: Polymers, Lithography, Extreme ultraviolet, Atomic force microscopy, Semiconducting wafers, Scanning electron microscopy, Extreme ultraviolet lithography, Chemistry, Photoresist materials, Scanners

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SPIE Journal Paper | 10 July 2012

Frequency multiplication of lamellar phase block copolymers with grapho-epitaxy directed self-assembly sensitivity to prepattern

Roel Gronheid, Paulina Rincon Delgadillo, Ivan Pollentier, Paul Nealey, Todd Younkin, Mark Somervell, Joshua Hooge, Kathleen Nafus

JM3, Vol. 11, Issue 3, 031303, (July 2012) https://doi.org/10.1117/12.10.1117/1.JMM.11.3.031303

KEYWORDS: Scanning electron microscopy, Semiconducting wafers, Optical lithography, Reticles, Image processing, Coating, Photoresist processing, Photomasks, Photoresist materials, Directed self assembly

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Proceedings Article | 23 March 2012 Paper

Quantification of shot noise contributions to contact hole local CD nonuniformity

Roel Gronheid, Gustaf Winroth, Alessandro Vaglio Pret, Todd Younkin

Proceedings Volume 8322, 83220M (2012) https://doi.org/10.1117/12.916681

KEYWORDS: Photons, Photomasks, Stochastic processes, Extreme ultraviolet, Extreme ultraviolet lithography, Nanoimprint lithography, Lithography, Critical dimension metrology, Image processing, Polymers

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Proceedings Article | 23 March 2012 Paper

Impact of EUV mask surface roughness on LER

Alessandro Vaglio Pret, Roel Gronheid, Todd Younkin, Michael Leeson, Pei-Yang Yan

Proceedings Volume 8322, 83220N (2012) https://doi.org/10.1117/12.916632

KEYWORDS: Photomasks, Surface roughness, Line edge roughness, Extreme ultraviolet lithography, Extreme ultraviolet, Semiconducting wafers, Chromium, Reticles, Plasma, High volume manufacturing

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Proceedings Article | 23 March 2012 Paper

Evaluation of resist performance with EUV interference lithography for sub-22-nm patterning

Yasin Ekinci, Michaela Vockenhuber, Bernd Terhalle, Mohamad Hojeij, Li Wang, Todd Younkin

Proceedings Volume 8322, 83220W (2012) https://doi.org/10.1117/12.916541

KEYWORDS: Line edge roughness, Extreme ultraviolet, Scanning electron microscopy, Extreme ultraviolet lithography, Lithography, Diffraction gratings, Photomasks, Optical lithography, Diffraction, Electron beam lithography

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Proceedings Article | 21 March 2012 Paper

EUVL compatible LER solutions using functional block copolymers

Han-Hao Cheng, Imelda Keen, Anguang Yu, Ya-Mi Chuang, Idriss Blakey, Kevin Jack, Michael Leeson, Todd Younkin, Andrew Whittaker

Proceedings Volume 8323, 83231O (2012) https://doi.org/10.1117/12.916744

KEYWORDS: Line edge roughness, Extreme ultraviolet lithography, Picosecond phenomena, Polymers, Lithography, Directed self assembly, Photoresist materials, Etching, Glasses, Reactive ion etching

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Proceedings Article | 20 March 2012 Paper

Critical material properties for pattern collapse mitigation

Gustaf Winroth, Todd Younkin, James Blackwell, Roel Gronheid

Proceedings Volume 8325, 83250R (2012) https://doi.org/10.1117/12.916364

KEYWORDS: Polymers, Lithography, Extreme ultraviolet, Semiconducting wafers, Scanning electron microscopy, Atomic force microscopy, Extreme ultraviolet lithography, Chemistry, Chemically amplified resists, Photoresist materials

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Proceedings Article | 15 March 2012 Paper

Comparison of directed self-assembly integrations

Mark Somervell, Roel Gronheid, Joshua Hooge, Kathleen Nafus, Paulina Rincon Delgadillo, Chris Thode, Todd Younkin, Koichi Matsunaga, Ben Rathsack, Steven Scheer, Paul Nealey

Proceedings Volume 8325, 83250G (2012) https://doi.org/10.1117/12.916406

KEYWORDS: Semiconducting wafers, Image processing, Optical lithography, Thin film coatings, Lithography, Etching, Reticles, Scanners, Scanning electron microscopy, Directed self assembly

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SPIE Journal Paper | 1 July 2011

Extreme-ultraviolet secondary electron blur at the 22-nm half pitch node

Roel Gronheid, Todd Younkin, Michael Leeson, Carlos Fonseca, Joshua Hooge, Kathleen Nafus, John Biafore, Mark Smith

JM3, Vol. 10, Issue 03, 033004, (July 2011) https://doi.org/10.1117/12.10.1117/1.3607429

KEYWORDS: Data modeling, Extreme ultraviolet, Diffusion, Stochastic processes, Line width roughness, Extreme ultraviolet lithography, Polymers, Absorption, Solids, Critical dimension metrology

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Proceedings Article | 16 April 2011 Paper

Addressing challenges in lithography using sub-millisecond post exposure bake of chemically amplified resists

Byungki Jung, Christopher Ober, Michael Thompson, Todd Younkin, Manish Chandhok

Proceedings Volume 7972, 797219 (2011) https://doi.org/10.1117/12.879288

KEYWORDS: Diffusion, Carbon dioxide lasers, Extreme ultraviolet lithography, Temperature metrology, Annealing, Deep ultraviolet, Lithography, Chemically amplified resists, Polymers, Semiconducting wafers

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Proceedings Article | 8 April 2011 Paper

EUVL dark-field exposure impact on CDs using thick and thin absorber masks

Sang Lee, Todd Younkin, Michael Leeson, Manish Chandhok, Guojing Zhang, John Magana, Hiroyoshi Tanabe, Steve Carson

Proceedings Volume 7969, 79691R (2011) https://doi.org/10.1117/12.879428

KEYWORDS: Photomasks, Extreme ultraviolet lithography, Cadmium sulfide, Extreme ultraviolet, Line width roughness, Lithography, Reflection, Electroluminescence, Phase shifting, Semiconducting wafers

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Proceedings Article | 8 April 2011 Paper

EUV lithography for 22nm half pitch and beyond: exploring resolution, LWR, and sensitivity tradeoffs

E. Steve Putna, Todd Younkin, Michael Leeson, Roman Caudillo, Terence Bacuita, Uday Shah, Manish Chandhok

Proceedings Volume 7969, 79692K (2011) https://doi.org/10.1117/12.879641

KEYWORDS: Line width roughness, Extreme ultraviolet, Extreme ultraviolet lithography, Photoresist processing, Photoresist materials, Photoresist developing, Materials processing, Lithography, Etching, Scanning electron microscopy

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Proceedings Article | 4 April 2011 Paper

Electron beam induced freezing of positive tone, EUV resists for directed self assembly applications

Han-Hao Cheng, Imelda Keen, Anguang Yu, Ya-Mi Chuang, Idriss Blakey, Kevin Jack, Michael Leeson, Todd Younkin, Andrew Whittaker

Proceedings Volume 7970, 79701V (2011) https://doi.org/10.1117/12.881491

KEYWORDS: Electron beam lithography, Annealing, Double patterning technology, Extreme ultraviolet, Line edge roughness, Electron beams, Directed self assembly, Scanning electron microscopy, Extreme ultraviolet lithography, Photoresist materials

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Proceedings Article | 25 March 2011 Paper

EUV secondary electron blur at the 22nm half pitch node

Roel Gronheid, Todd Younkin, Michael Leeson, Carlos Fonseca, Joshua Hooge, Kathleen Nafus, John Biafore, Mark Smith

Proceedings Volume 7969, 796904 (2011) https://doi.org/10.1117/12.881427

KEYWORDS: Data modeling, Diffusion, Line width roughness, Extreme ultraviolet, Stochastic processes, Extreme ultraviolet lithography, Polymers, Absorption, Solids, Critical dimension metrology

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Proceedings Article | 26 March 2010 Paper

Aqueous and solvent developed negative-tone molecular resists

Richard Lawson, Jing Cheng, David Noga, Todd Younkin, Laren Tolbert, Clifford Henderson

Proceedings Volume 7639, 76390O (2010) https://doi.org/10.1117/12.848414

KEYWORDS: Molecules, Electron beam lithography, Deep ultraviolet, Line edge roughness, Polymers, Polymerization, Glasses, Dewetting, Optical lithography, Scanning electron microscopy

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Proceedings Article | 26 March 2010 Paper

Sub-millisecond post exposure bake of chemically amplified resists by CO2 laser heat treatment

Byungki Jung, Jing Sha, Florencia Paredes, Christopher Ober, Michael Thompson, Manish Chandhok, Todd Younkin

Proceedings Volume 7639, 76390L (2010) https://doi.org/10.1117/12.848418

KEYWORDS: Diffusion, Deep ultraviolet, Carbon dioxide lasers, Polymers, Annealing, Imaging systems, Extreme ultraviolet lithography, Chemically amplified resists, Temperature metrology, Absorption

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Proceedings Article | 23 March 2010 Paper

Polycarbonate based nonchemically amplified photoresists for extreme ultraviolet lithography

Idriss Blakey, Anguang Yu, James Blinco, Kevin Jack, Heping Liu, Michael Leeson, Wang Yueh, Todd Younkin, Andrew Whittaker

Proceedings Volume 7636, 763635 (2010) https://doi.org/10.1117/12.853620

KEYWORDS: Polymers, Extreme ultraviolet lithography, Extreme ultraviolet, Line edge roughness, Absorbance, Optical lithography, Semiconducting wafers, Carbonates, Scanning electron microscopy, Photoresist materials

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Proceedings Article | 23 March 2010 Paper

Aerial image improvements on the Intel MET

Roman Caudillo, Todd Younkin, Steve Putna, Alan Myers, Yashesh Shroff, Terence Bacuita, Grant Kloster, Erik Sohmen

Proceedings Volume 7636, 76363I (2010) https://doi.org/10.1117/12.849142

KEYWORDS: Line width roughness, Extreme ultraviolet lithography, Extreme ultraviolet, Mirrors, Photoresist materials, Semiconducting wafers, Printing, Modulation, Photomasks, Photoresist developing

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Proceedings Article | 20 March 2010 Paper

EUV lithography for 22nm half pitch and beyond: exploring resolution, LWR, and sensitivity tradeoffs

E. Steve Putna, Todd Younkin, Roman Caudillo, Manish Chandhok

Proceedings Volume 7636, 76360P (2010) https://doi.org/10.1117/12.842408

KEYWORDS: Line width roughness, Extreme ultraviolet, Extreme ultraviolet lithography, Standards development, Lithography, Photoresist processing, Optical lithography, Photoresist materials, Lithographic illumination, Lead

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Proceedings Article | 20 March 2010 Paper

Printability of extreme ultraviolet lithography mask pattern defects for 22-40 nm half-pitch features

Grant Kloster, Ted Liang, Todd Younkin, Ernisse Putna, Roman Caudillo, Il-Seok Son

Proceedings Volume 7636, 76360M (2010) https://doi.org/10.1117/12.845740

KEYWORDS: Photomasks, Extreme ultraviolet lithography, Semiconducting wafers, Extreme ultraviolet, Scanning electron microscopy, Line width roughness, Optical lithography, Photoresist materials, Lithography, Metrology

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Proceedings Article | 1 April 2009 Paper

Elucidating the physiochemical and lithographic behavior of ultra-thin photoresist films

Annapoorani Sundaramoorthi, Todd Younkin, Clifford Henderson

Proceedings Volume 7273, 72733V (2009) https://doi.org/10.1117/12.814410

KEYWORDS: Thin films, Temperature metrology, Photoresist materials, Glasses, Polymers, Polymer thin films, Interfaces, Lithography, Systems modeling, Thermal modeling

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As resist feature sizes and film thicknesses continue to shrink in dimension, a number of resist feature size and film thickness dependent effects are being observed in the lithographic performance of high resolution photoresists. In order to understand these phenomena, a better understanding of the physiochemical behavior of complex multi-component organic resist thin films is needed. As a first step in that direction, a series of model photoresists were studied in an effort to begin to understand the thermophysical properties of such multi-component thin films. The influence of photoacid generator (PAG) loading and PAG chemistry on the glass transition behavior using the model photoresists was studied. A thermal flow experiment was used to characterize an "apparent glass transition temperature" of the resist thin films as a function of PAG type and loading. These results were compared to traditional glass transition measurements made on the same resist compositions using differential scanning calorimetry (DSC). The two methods, namely DSC and the thermal flow measurement, yielded very different results depending on the type of PAG used. Further studies using ToF SIMS to profile the distribution of PAG in the resist thin films revealed that the two PAGs focused on in this work, a triphenylsulfonium triflate (TPS.OTF) and a triphenylsulfonium nonaflate (TPS.ONF), exhibited very different distribution behavior in resist thin films. In the case of TPS.OTF, the PAG was observed to show a depletion region near the resistsubstrate interface while the TPS.ONF PAG was relatively homogeneously distributed in the resist thin films. In the case of TPS.ONF, it was also the resist system which showed very different thermophysical behavior when comparing the glass transition temperature measured using DSC to the thermal flow temperature measurement. This work points out the fact that component distribution and thin film effects must be carefully considered in interpreting and analyzing the behavior of multi-component thin films.

Proceedings Article | 1 April 2009 Paper

Lithographic evaluation and chemical modeling of acid amplifiers used in EUV photoresists

Robert Brainard, Craig Higgins, Seth Kruger, Srividya Revuru, Brian Cardineau, Sarah Gibbons, Dan Freedman, Harun Solak, Wang Yueh, Todd Younkin

Proceedings Volume 7273, 72733Q (2009) https://doi.org/10.1117/12.814308

KEYWORDS: Amplifiers, Line edge roughness, Lithography, Extreme ultraviolet lithography, Molecules, Oxygen, Thermal modeling, Thermodynamics, Photoresist materials, Polymers

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Proceedings Article | 1 April 2009 Paper

Negative-tone molecular resists based on cationic polymerization

Richard Lawson, Laren Tolbert, Todd Younkin, Clifford Henderson

Proceedings Volume 7273, 72733E (2009) https://doi.org/10.1117/12.814455

KEYWORDS: Line edge roughness, Polymerization, Electron beam lithography, Glasses, Image resolution, Diffusion, Line width roughness, Molecules, Epoxies, Scanning electron microscopy

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Proceedings Article | 1 April 2009 Paper

EUV lithography for 30nm half pitch and beyond: exploring resolution, sensitivity, and LWR tradeoffs

E. Steve Putna, Todd Younkin, Manish Chandhok, Kent Frasure

Proceedings Volume 7273, 72731L (2009) https://doi.org/10.1117/12.814191

KEYWORDS: Line width roughness, Extreme ultraviolet, Extreme ultraviolet lithography, Polymers, Photoresist processing, Standards development, Optical lithography, Glasses, Lithography, Photoresist materials

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Proceedings Article | 1 April 2009 Paper

Incorporating organosilanes into EUV photoresists: diphenyltrimethylsilylmethylsulfonium triflate as a new PAG

Shalini Sharma, Yoichi Ogata, Clarion Tung, James Blackwell, Todd Younkin, Yoshi Hishiro, Joshua Figueroa, Arnold Rheingold

Proceedings Volume 7273, 72733N (2009) https://doi.org/10.1117/12.814220

KEYWORDS: Extreme ultraviolet lithography, Line width roughness, Optical transfer functions, Optical lithography, Photoresist materials, Semiconducting wafers, Chemistry, Extreme ultraviolet, Polymers, Lithography

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Proceedings Article | 1 April 2009 Paper

Aryl sulfonates as neutral photoacid generators (PAGs) for EUV lithography

Robert Sulc, James Blackwell, Todd Younkin, E. Steve Putna, Katherine Esswein, Antonio DiPasquale, Ryan Callahan, Hideaki Tsubaki, Tooru Tsuchihashi

Proceedings Volume 7273, 72733R (2009) https://doi.org/10.1117/12.814279

KEYWORDS: Extreme ultraviolet lithography, Lithography, Photoresist materials, Extreme ultraviolet, Optical lithography, Line width roughness, Molecules, Ionization, Semiconducting wafers, Lithium

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Proceedings Article | 1 April 2009 Paper

Underlayer designs to enhance the performance of EUV resists

Hao Xu, James Blackwell, Todd Younkin, Ke Min

Proceedings Volume 7273, 72731J (2009) https://doi.org/10.1117/12.814223

KEYWORDS: Extreme ultraviolet, Line width roughness, Extreme ultraviolet lithography, Polymers, Scanning electron microscopy, Photoresist materials, Semiconducting wafers, Neodymium, Molecules, Optical lithography

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Proceedings Article | 1 April 2009 Paper

Characterization of the photoacid diffusion length

Shuhui Kang, Vivek Prabhu, Wen-li Wu, Eric Lin, Kwang-Woo Choi, Manish Chandhok, Todd Younkin, Wang Yueh

Proceedings Volume 7273, 72733U (2009) https://doi.org/10.1117/12.813555

KEYWORDS: Diffusion, Photoresist materials, Extreme ultraviolet lithography, Switches, Lithography, Line edge roughness, Photoresist developing, Polymers, Deep ultraviolet, Extreme ultraviolet

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Proceedings Article | 1 April 2009 Paper

Sensitivity of EUV resists to out-of-band radiation

Jeanette Roberts, Robert Bristol, Todd Younkin, Theodore Fedynyshyn, David Astolfi, Alberto Cabral

Proceedings Volume 7273, 72731W (2009) https://doi.org/10.1117/12.814342

KEYWORDS: Extreme ultraviolet, Absorbance, Reflectivity, Semiconducting wafers, Polymers, Extreme ultraviolet lithography, Mirrors, Lithography, Silicon, Titanium dioxide

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Proceedings Article | 1 April 2009 Paper

Development of polymers for non-CAR resists for EUV lithography

Andrew Whittaker, Idriss Blakey, James Blinco, Kevin Jack, Kirsten Lawrie, Heping Liu, Anguang Yu, Michael Leeson, Wang Yeuh, Todd Younkin

Proceedings Volume 7273, 727321 (2009) https://doi.org/10.1117/12.820493

KEYWORDS: Polymers, Photons, Stars, Extreme ultraviolet, Polymethylmethacrylate, Extreme ultraviolet lithography, Polymerization, Etching, Resistance, Magnesium

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Proceedings Article | 18 March 2009 Paper

Demonstration of full-field patterning of 32 nm test chips using EUVL

Gilroy Vandentop, Manish Chandhok, Ernisse Putna, Todd Younkin, James Clarke, Steven Carson, Alan Myers, Michael Leeson, Guojing Zhang, Ted Liang, Tetsunori Murachi

Proceedings Volume 7271, 727116 (2009) https://doi.org/10.1117/12.814436

KEYWORDS: Photomasks, Extreme ultraviolet lithography, Inspection, Optical lithography, Extreme ultraviolet, Particles, Photoresist materials, Line width roughness, Reticles, Semiconducting wafers

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Proceedings Article | 18 March 2009 Paper

Assessment of EUV resist readiness for 32-nm hp manufacturing and extendibility study of EUV ADT using state-of-the-art resist

Chawon Koh, Liping Ren, Jacque Georger, Frank Goodwin, Stefan Wurm, Bill Pierson, Joo-On Park, Tom Wallow, Todd Younkin, Patrick Naulleau

Proceedings Volume 7271, 727124 (2009) https://doi.org/10.1117/12.814314

KEYWORDS: Semiconducting wafers, Manufacturing, Extreme ultraviolet lithography, Extreme ultraviolet, Line width roughness, Photoresist processing, Optical lithography, Photomasks, Electroluminescence, Critical dimension metrology

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Proceedings Article | 15 April 2008 Paper

Effect of PAG and matrix structure on PAG acid generation behavior under UV and high-energy radiation exposure

Cheng-Tsung Lee, Mingxing Wang, Kenneth Gonsalves, Wang Yueh, Jeanette Roberts, Todd Younkin, Clifford Henderson

Proceedings Volume 6923, 69232F (2008) https://doi.org/10.1117/12.782634

KEYWORDS: Polymers, Polymer thin films, Ionization, Picosecond phenomena, Deep ultraviolet, Absorption, Photoresist materials, Molecules, Matrices, Photolysis

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Chemically amplified resists (CAR) have successfully facilitated the development of deep ultra-violet (DUV) and 193 nm lithography techniques for more than two decades due to their acid-catalyzed deprotection scheme that enhances their photospeed. This acid-catalyzed mechanism provides a method for amplifying the initial chemical reactions caused by interaction of radiation with the resist film, thus making each interaction event between radiation and resist more productive. However, when switching from low energy photolysis to high energy radiolysis, changes in the manner in which the radiation interacts with the resist material can alter the acid generation efficiency and mechanism of PAG excitation. In high energy radiation cases where the radiation energy exceeds the ionization potential of the PAG and the polymer resin, the radiation absorption in the resist film becomes non-selective. The ratio of PAG excited by direct excitation as compared to polymer or matrix sensitization pathways can shift heavily in favor of matrix sensitization in such high energy exposure cases. Such sensitization pathways may become a potential method for enhancing resist sensitivity under high energy radiation through careful selection of matrix and PAG materials. A better understanding and study the efficiency of acid generation through direct and indirect PAG excitation pathways and the effect of PAG and matrix structure on these pathways would be extremely valuable for the design of future high sensitivity resist materials. In this work, the acid generation of typical ionic (onium salt) and non-ionic PAGs under DUV (248 nm) and electron-beam exposure in polymer film have been studied. The effect of PAG type and structure on its acid generation under photolysis and radiolysis has been determined. The effect of polymer resin structure on PAG photoacid generation under photolysis and radiolysis has also been investigated. Concepts for PAG and polymer design for producing enhanced sensitivity resists for excitational and ionizational exposure is discussed.

Proceedings Article | 26 March 2008 Paper

A new technique for studying photo-acid generator chemistry and physics in polymer films using on-wafer ellipsometry and acid-sensitive dyes

Cheng-Tsung Lee, Wang Yueh, Jeanette Roberts, Todd Younkin, Clifford Henderson

Proceedings Volume 6923, 692316 (2008) https://doi.org/10.1117/12.773393

KEYWORDS: Polymers, Polymer thin films, Polymethylmethacrylate, Absorbance, Ellipsometry, Lithography, Deep ultraviolet, Photolysis, Absorption, Chemistry

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Chemically amplified resists (CARs) are likely to continue to be the main resist materials platform for next generation lithography using shorter wavelength and higher energy radiation sources, such as extreme ultra-violet (EUV) and electron-beam (EB) lithography, to pattern features at and below the 32 nm technology node. As the cost of generating and manipulating high energy radiation in these techniques increases dramatically, photoacid generators (PAGs) with high sensitivities to these exposure sources are required to efficiently utilize such radiation and maintain high lithography tool throughputs. On the other hand, the high energy radiation used in current and next generation lithography tools can increasingly interact non-selectively with the PAG and polymer resin. Photoacid generation from PAG sensitization pathways involving the photoresist resin (e.g. polymer) becomes another potential route for boosting the photospeed of CARs if the PAG and matrix resin chemistry is selected properly. In this work, a fast, convenient, and material saving method which can measure the acid generation rate and yield under photolysis and radiolysis, as well as determine the efficiency of acid generation through direct PAG excitation and indirect PAG sensitization pathways has been developed. This method utilizes on-wafer ellipsometry to determine the absorption of protonated Courmarin 6 (C6) dye, which is incorporated into the polymer resin as a proton indicator. In this work, triphenylsulfonium triflate PAG is used in two different matrix resins, poly(methyl methacrylate) and poly(hydroxystyrene), to illustrate this point that matrix sensitization of the PAG can be important and can be studied using the method developed in this work. This study serves as the starting point for building the structure property relationships needed for intelligent PAG and matrix design to optimize exposure energy utilization in CARs. The validity of this new analytical method is verified by comparing our results in selected PAG-polymer combinations with results obtained from previous studies using different techniques. The potential measurement errors possible when using dye as the proton indicator in a solid-state medium, such as the probability of proton-dye contact and acid generation through dye radiation absorption and sensitization of the PAG, are also analyzed and discussed in this paper.

Showing 5 of 41 publications

Proceedings Volume Editor (1)

SPIE Conference Volume | 6 June 2016

Advances in Patterning Materials and Processes XXXIII

Conference Committee Involvement (9)

Advances in Patterning Materials and Processes XXXIII

29 February 2016 | San Jose, California, United States

Alternative Lithographic Technologies VIII

22 February 2016 | San Jose, California, United States

Advances in Patterning Materials and Processes XXXII

24 February 2015 | San Jose, California, United States

Alternative Lithographic Technologies VII

23 February 2015 | San Jose, California, United States

Advances in Patterning Materials and Processes XXXI

24 February 2014 | San Jose, California, United States

Showing 5 of 9 Conference Committees

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