Dr. Wang Yueh Profile

Dr. Wang Yueh

Principal Engineer

SPIE Involvement:

Author

Publications (27)

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 | 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

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 | 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 | 27 March 2008 Paper

Single molecule chemically amplified resists based on ionic and non-ionic PAGs

Richard Lawson, Cheng-Tsung Lee, Wang Yueh, Laren Tolbert, Clifford Henderson

Proceedings Volume 6923, 69230K (2008) https://doi.org/10.1117/12.773570

KEYWORDS: Molecules, Line edge roughness, Glasses, Diffusion, Image resolution, Deep ultraviolet, Polymers, Extreme ultraviolet lithography, Etching, Chemically amplified resists

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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

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.

Proceedings Article | 26 March 2008 Paper

Water-developable negative-tone single-molecule resists: high-sensitivity nonchemically amplified resists

Richard Lawson, Cheng-Tsung Lee, Wang Yueh, Laren Tolbert, Clifford Henderson

Proceedings Volume 6923, 69231I (2008) https://doi.org/10.1117/12.773188

KEYWORDS: Molecules, Image resolution, Imaging systems, Line edge roughness, Electron beam lithography, Deep ultraviolet, Chemically amplified resists, Image processing, Switching, Diffusion

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Proceedings Article | 26 March 2008 Paper

Synthesis and properties of new anionic photoacid generators bound polymer resists for e-beam and EUV lithography

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

Proceedings Volume 6923, 692312 (2008) https://doi.org/10.1117/12.769004

KEYWORDS: Polymers, Absorption, Extreme ultraviolet lithography, Deep ultraviolet, Lithography, Line edge roughness, Polymer thin films, NOx, Silicon, Scanning electron microscopy

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Proceedings Article | 26 March 2008 Paper

Mesoscale simulation of molecular glass photoresists: effect of PAG loading and acid diffusion coefficient

Richard Lawson, Cheng-Tsung Lee, Wang Yueh, Laren Tolbert, Clifford Henderson

Proceedings Volume 6923, 69230Q (2008) https://doi.org/10.1117/12.774619

KEYWORDS: Line edge roughness, Diffusion, Molecules, Glasses, Critical dimension metrology, Polymers, Photoresist materials, Chemically amplified resists, Lithography, Solid modeling

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Proceedings Article | 6 April 2007 Paper

The rational design of polymeric EUV resist materials by QSPR modelling

Kevin Jack, Heping Liu, Idriss Blakey, David Hill, Wang Yueh, Heidi Cao, Michael Leeson, Greg Denbeaux, Justin Waterman, Andrew Whittaker

Proceedings Volume 6519, 65193Z (2007) https://doi.org/10.1117/12.716213

KEYWORDS: Polymers, Extreme ultraviolet, Data modeling, Molecules, Photons, Ionization, Process modeling, Polymethylmethacrylate, Modeling, Spectroscopy

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Proceedings Article | 4 April 2007 Paper

An analysis of EUV-resist outgassing measurements

Kim Dean, Iwao Nishiyama, Hiroaki Oizumi, Anthony Keen, Heidi Cao, Wang Yueh, Takeo Watanabe, Paolo Lacovig, Luca Rumiz, Gregory Denbeaux, Julia Simon

Proceedings Volume 6519, 65191P (2007) https://doi.org/10.1117/12.712379

KEYWORDS: Extreme ultraviolet, Extreme ultraviolet lithography, Synchrotrons, Contamination, Mass spectrometry, Molecules, Mirrors, Analytical research, Calibration, EUV optics

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Proceedings Article | 23 March 2007 Paper

Novel polymeric anionic photo-acid generators (PAGs) and photoresists for sub-100-nm patterning by 193-nm lithography

Mingxing Wang, Nathan Jarnagin, Wang Yueh, Jeanette Roberts, Melina Tapia-Tapia, Nikola Batina, Kenneth Gonsalves

Proceedings Volume 6519, 65192C (2007) https://doi.org/10.1117/12.711477

KEYWORDS: Polymers, Fluorine, Line edge roughness, Lithography, Photoresist materials, Optical lithography, Polymerization, Etching, Resistance, Semiconducting wafers

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Proceedings Article | 23 March 2007 Paper

Novel anionic photoacid generator (PAGs) and photoresist for sub-50-nm patterning by EUVL and EBL

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

Proceedings Volume 6519, 65191F (2007) https://doi.org/10.1117/12.712143

KEYWORDS: Polymers, Extreme ultraviolet lithography, Line edge roughness, Extreme ultraviolet, Photoresist materials, Electron beam lithography, Lithography, Polymerization, Image processing, Optical lithography

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Proceedings Article | 23 March 2007 Paper

Photosensitivity and line-edge roughness of novel polymer-bound PAG photoresists

Cheng-Tsung Lee, Mingxing Wang, Nathan Jarnagin, Kenneth Gonsalves, Jeanette Roberts, Wang Yueh, Clifford Henderson

Proceedings Volume 6519, 65191E (2007) https://doi.org/10.1117/12.713369

KEYWORDS: Polymers, Line edge roughness, Lithography, Analog electronics, Diffusion, Image resolution, Polymer thin films, Silicon, Photoresist materials, Semiconducting wafers

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Substantially improved photoresist material designs, which can provide higher photosensitivity and precise critical dimension and edge roughness control, will be required to enable the application of next generation lithography technology to the production of future sub-65 nm node IC device generations. The development and characterization of novel material platforms that solve the aforementioned basic problems with chemically amplified resists (CARs) is essential and is already one of the major subjects of modern lithography research. In that regard, we have pursued development of a variety of 193 nm and EUV CARs that contain photoacid generator (PAG) units covalently bonded directly to the resin polymer backbone. However, the detailed structure-property relationships that result from this direct attachment of the PAG functional group to the polymer have previously not yet been rigorously characterized. In this work, the lithographic properties of a polymer-bound PAG CAR (GBLMA-co-EAMA-co-F4-MBS.TPS) and its blended-PAG analog resist (GBLMA-co-EAMA blend F4-IBBS.TPS) were studied and compared. The direct incorporation of PAG functionality into the resist polymer, where the resulting photoacid remains bound to the polymer, showed improved photosensitivity, resolution, and lower LER as compared with the analogous blended-PAG resist. The improved resolution and LER were expected due to the restricted photoacid diffusion and uniform PAG distribution provided by direct incorporation of the PAG into the polymer backbone to make a single-component resist material. The ability to load higher levels of PAG into the resist provided by this PAG incorporation into the polymer, as compared to the low PAG concentrations attainable by traditional blending approaches, overcomes the sensitivity loss that should result from reduction in photoacid diffusivity and concomitant smaller acid-catalytic chain lengths. In fact, the polymer-bound PAG resist achieves a faster photospeed than the blended-PAG analog material under DUV radiation in the case of the materials reported here while still providing all of the aforementioned improvements such as the improved line edge roughness.

Proceedings Article | 21 March 2007 Paper

Molecular glass photoresists containing photoacid generator functionality: a route to a single-molecule photoresist

Richard Lawson, Cheng-Tsung Lee, Robert Whetsell, Wang Yueh, Jeanette Roberts, Laren Tolbert, Clifford Henderson

Proceedings Volume 6519, 65191N (2007) https://doi.org/10.1117/12.712928

KEYWORDS: Glasses, Line edge roughness, Etching, Polymers, Photoresist materials, Deep ultraviolet, Extreme ultraviolet lithography, Diffusion, Molecules, Reactive ion etching

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Proceedings Article | 31 March 2006 Paper

Fundamental studies of the properties of photoresists based on resins containing polymer-bound photoacid generators

Cheng-Tsung Lee, Nathan Jarnagin, Mingxing Wang, Kenneth Gonsalves, Jeanette Robert, Wang Yueh, Clifford Henderson

Proceedings Volume 6153, 61532E (2006) https://doi.org/10.1117/12.663410

KEYWORDS: Polymers, Data modeling, Diffusion, Photoresist materials, FT-IR spectroscopy, Statistical modeling, Molecules, Extreme ultraviolet lithography, Polymer thin films, Reflectivity

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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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Proceedings Article | 4 May 2005 Paper

Quantification of EUV resist outgassing

Wang Yueh, Heidi Cao, Vani Thirumala, Hokkin Choi

Proceedings Volume 5753, (2005) https://doi.org/10.1117/12.600540

KEYWORDS: Extreme ultraviolet lithography, Extreme ultraviolet, Photoresist materials, Contamination, EUV optics, Nitrogen, Semiconducting wafers, Molecules, Lithography, Reflectivity

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Proceedings Article | 4 May 2005 Paper

EUV resist patterning performance from the Intel microexposure tool (MET)

Heidi Cao, Wang Yueh, Jeanette Roberts, Bryan Rice, Robert Bristol, Manish Chandhok

Proceedings Volume 5753, (2005) https://doi.org/10.1117/12.600214

KEYWORDS: Line width roughness, Extreme ultraviolet, Optical lithography, Absorbance, Scatterometry, Scanning electron microscopy, Lithography, Scatter measurement, Image resolution, Extreme ultraviolet lithography

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Proceedings Article | 20 May 2004 Paper

Techniques for directly measuring the absorbance of photoresists at EUV wavelengths

Manish Chandhok, Heidi Cao, Wang Yueh, Eric Gullikson, Robert Brainard, Stewart Robertson

Proceedings Volume 5374, (2004) https://doi.org/10.1117/12.535959

KEYWORDS: Absorbance, Reflectivity, Photoresist materials, Semiconducting wafers, Silicon, Extreme ultraviolet, Grazing incidence, Refraction, Extreme ultraviolet lithography, X-rays

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Proceedings Article | 14 May 2004 Paper

Patterning capabilities of EUV resists

Wang Yueh, Heidi Cao, Manish Chandhok, Sang Lee, Michael Shumway, Jeff Bokor

Proceedings Volume 5376, (2004) https://doi.org/10.1117/12.536021

KEYWORDS: Line width roughness, Photoresist materials, Extreme ultraviolet, Extreme ultraviolet lithography, Absorbance, Optical lithography, Lithography, Line edge roughness, Polymers, Manufacturing

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Proceedings Article | 14 May 2004 Paper

Characterization of outgassing for EUV technology

Vani Thirumala, Heidi Cao, Wang Yueh, Hokkin Choi, Victoria Golovkina, John Wallace, Paul Nealey, Don Thielman, Franco Cerrina

Proceedings Volume 5376, (2004) https://doi.org/10.1117/12.536052

KEYWORDS: Extreme ultraviolet lithography, Photoresist materials, Toxic industrial chemicals, Contamination, Extreme ultraviolet, Silicon, EUV optics, Lithography, Semiconducting wafers, Chemistry

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Proceedings Article | 14 May 2004 Paper

Sources of line-width roughness for EUV resists

Heidi Cao, Wang Yueh, Bryan Rice, Jeanette Roberts, Terence Bacuita, Manish Chandhok

Proceedings Volume 5376, (2004) https://doi.org/10.1117/12.536041

KEYWORDS: Line width roughness, Photoresist materials, Polymers, Diffusion, Molecules, Extreme ultraviolet, Line edge roughness, Scanning electron microscopy, Lithography, Edge roughness

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Proceedings Article | 11 June 1999 Paper

Impact of photoacid generator structure on DUV resist performance

James Cameron, Sheri Ablaza, Guangyu Xu, Wang Yueh

Proceedings Volume 3678, (1999) https://doi.org/10.1117/12.350268

KEYWORDS: Lithography, Deep ultraviolet, Diffusion, Prototyping, Absorbance, Chromophores, Chemistry, Image resolution, Electroluminescence, Photoresist processing

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Proceedings Article | 7 July 1997 Paper

Non-chemically amplified 248-nm resist materials

C. Grant Willson, Wang Yueh, Michael Leeson, Thomas Steinhaeusler, Christopher McAdams, Ralph Dammel, James Sounik, M. Aslam, Richard Vicari, Michael Sheehan

Proceedings Volume 3049, (1997) https://doi.org/10.1117/12.275821

KEYWORDS: Deep ultraviolet, Absorbance, Analog electronics, Chromophores, Lithography, Chemically amplified resists, Ultraviolet radiation, Manufacturing, Lamps, Excimer lasers

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Remarkable progress has been made in the formulation of chemically amplified resists for deep-UV (DUV or 248 nm) lithography. These materials are now in general use in full scale manufacturing. One of the deterrents to rapid and universal adoption of DUV lithography has been the combination of high cost of ownership and a narrow process latitude when compared to conventional i-line process alternatives. A significant part of the high cost of the DUV process is associated with installing and maintaining special air handling equipment that is required to remove basic contaminants from the ambient. Manufacture process latitude demands this special air handling. The chemically amplified resists were developed originally to support mercury lamp powered exposure systems. The sensitivity realized by chemical amplification is required to enable useful productivity with such systems that generate very little DUV flux at the wafer plane. With the advent of high powered excimer laser based illumination systems for 248 nm steppers and step-and-scan systems, it is appropriate to re-examine the applicability of non-chemically amplified DUV resist systems. These systems are less sensitive but have the potential to offer both lower cost of ownership and improved process latitude. A series of photoactive compounds (PACs) have been synthesized and auditioned for use in the formulation of a non-chemically amplified 248 nm resist. The most promising of these materials are analogs of 3-oxo-3-diazocoumarin. This chromophore displays photochemistry that is analogous to that of the diazonaphthoquinones (DNQ) that are the basis of i-line resist formulations, but it bleaches at 248 nm. Several structural analogs of the chromophore have been synthesized and a variety of ballast groups have been studied with the goal of enhancing the dissolution inhibition properties of the molecule. The diazocoumarin PACs have been formulated with customized phenolic resins that were designed to provide the combination of optical transparency, dry etch resistance and the dissolution characteristics that are required for manufacturing applications. The resins are copolymers of poly(4-hydroxystyrene) and blends of these polymers with novolac.