Jing Sha

Research Interests:
Unconventional lithographic processing: two-photon lithography,  supercritical CO₂ development, laser spike annealing as post-exposure bake (PEB) and characterization of physical and structural properties of photoresists.

• In two-photon lithography, a single laser beam is focused to excite photoacid generators (PAGs) or photoinitiators in photoresists and trigger subsequent chemical reactions. Since two-photon absorption by photoacid generators or photoinitiators highly depends on photon intensity and distance from the focal point, only at the focal point are there enough photons that can simultaneously to excite PAG or photoinitiator molecules from a lower to higher energy level. Also, as most photoresists absorb very little in the near IR regime, three-dimensional structures can be patterned inside photoresists.
  
• Supercritical CO₂ has been explored as an environmentally friendly developer for photoresists, especially molecular glass resists. CO₂ has zero dipole but non-zero quadruple moment, which makes it a selective developer. Since supercritical CO₂ is a one-phase fluid and there exits no surface tension during development, collapse of patterns, especially those with high aspect ratios, can be avoided.
  
• While PEB of chemically amplified resists are conventionally done on a hot plate at a temperature of 90-150 °C for 30-120 s, laser spike annealing makes it possible to access very short PEB time in the sub-millisecond regime in an attempt to reduce the line-edge roughness and enhance resist sensitivity.

Recent Publications:

• Jing Sha, Byungki Jung, Michael O. Thompson, Christopher K. Ober, Manish Chandhok, Todd R. Younkin, Sub-millisecond Post Exposure Bake of Chemically Amplified Resists by CO2 Laser Spike Annealing, submitted (2009).
• Woo Jin Bae, Markos Trikeritotis, Jing Sha, Evan Schwartz, Robert Rodriguez, Paul Zimmerman, Emmanuel P. Giannelis, Christopher K. Ober, High Index Nanocomposite Photoresist with HfO2 Nanoparticles, in preparation (2009).
•  Jing Sha, Jin-Kyun Lee, Christopher K. Ober, Molecular Glass Resists Developable in Supercritical CO2 for 193-nm Lithography, Proceedings of SPIE, 7273, 72732T (2009).
• Marie E. Krysak, Anuja De Silva, Jing Sha, Jin-Kyun Lee, Christopher K. Ober, High-Resolution Molecular Glass Resists for Next Generation Lithography, Proceedings of SPIE, 7273, 72732N (2009).
• Jin-Kyun Lee, Margarita Chatzichristidi, Alexander A. Zakhidov, Ha Soo Hwang, Evan L. Schwartz, Jing Sha, Priscilla G. Taylor, Hon Hang Fong, John A. DeFranco, Eisuke Murotani, Wallace W. H. Wong, George G. Malliaras, Christopher K. Ober, Acid Diusion Behaviour in Organic Thin Films and its Effect on Patterning, J. of Mater. Chem., 19, 2986 (2009).
• Jing Sha, Christopher K. Ober, Fluorine- and Siloxane-Containing Polymers for Supercritical Carbon Dioxide Lithography, Polymer International, 58, 302 (2009).
• Georgia E. McCluskey, Jin-Kyun Lee, Jing Sha, Christopher K. Ober, Scott E. Watkins, Andrew B. Holmes, Synthesis and Processing of Organic Materials in Supercritical Carbon Dioxide, MRS Bulletin, 34, 2, 108 (2009).
• Lorenz Steidl, Shalin J. Jhaveri, Ayothi Ramakrishnan, Jing Sha, Jesse D. McMullen, Sin Yee Cindy Ng, Warren Zipfel, Rudolf Zentel, Christopher K. Ober, Non-ionic photo-acid generators for applications in two-photon lithography, J. of Mater. Chem., 19, 514 (2009).
• Nelson M. Felix, Anuja De Silva, Jing Sha, Christopher K. Ober, Achieving Small Dimensions with an Environmentally Friendly Solvent: Photoresist Development Using Supercritical CO2, Proceedings of SPIE (2008), 6923, 69233L-69233L-11.
• Anuja De Silva, Nelson Felix, Jing Sha, Christopher K. Ober, Molecular Glass Resists for Next Generation Lithography, Proceedings of SPIE (2008), 6923, 69231L/1-69231L/14.
• Anuja De Silva, Nelson Felix, Drew Forman, Jing Sha, Christopher K. Ober, New Architectures for High Resolution Patterning, Proceedings of SPIE (2008), 6923, 69230O/1-69230O/9.