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MEMS-based Gray-scale Technology Lance Mosher    Collaborators - Dr. Alan H. Epstein, Gas Turbine Lab, MIT - Dr. John Krizmanic, NASA Goddard Space Flight Center    Research Overview Gray-scale lithography is a useful technique for developing 3-D structures in a photoresist layer. Dry anisotropic etching, typically deep reactive ion etching (DRIE), can then be used to transfer such structures into an underlying silicon substrate. Our work includes the modeling and characterization of both the lithography and etching steps, as well as development of techniques for integrating 3-D structures into new MEMS devices. Applications currently being pursued include: the development of 3-D powerMEMS components, fabrication of 3-D packaging substrates for angled interconnects, modifying electrostatic actuator performance using variable-height components, and development of stepped phase Fresnel lenses for soft x-rays.    Thesis Brian C. Morgan, "Electrostatic MEMS Actuators using Gray-scale Technology," PhD Thesis, University of Maryland - College Park, MD, August 2006. Brian C. Morgan, "Development of a Deep Silicon Phase Fresnel Lens using Gray-Scale Lithography and Deep Reactive Ion Etching," Master's Thesis, University of Maryland, College Park, MD, May 2004. Christopher M. Waits, "Investigation of Gray-scale Technology for Large Area 3-D Silicon Structures," Master's Thesis, University of Maryland, College Park, MD, April 2003.    Journal Papers B. Morgan, and R. Ghodssi, "Vertically-shaped Tunable MEMS Resonators," Journal of Microelectromechanical Systems (JMEMS), Vol. 17, No. 1, pp. 85-92, 2008. B. Morgan, J. McGee, and R. Ghodssi, "Automated 2-Axis Optical Fiber Alignment using Gray-scale Technology," Journal of Microelectromechanical Systems (JMEMS), Vol. 16, No. 16, pp. 102-110, 2007. J. Krizmanic, B. Morgan, R. Streitmatter, N. Gehrels, K. Gendreau, Z. Arzoumanian, R. Ghodssi, and G. Skinner, "Development of Ground-testable Phase Frenel Lenses in Silicon," Experimental Astronomy, Vol. 20, pp. 299-306, 2005. B. Morgan, X. Hua, T. Iguchi, T. Tomioka, G. Oehrlein, and R. Ghodssi, "Substrate Interconnect Technologies for 3-D MEMS Packaging," Microelectronic Engineering, Vol. 81, pp. 106-116, July 2005. C.M. Waits, B. Morgan, M. J. Kastantin and R. Ghodssi, "Microfabrication of 3D Silicon MEMS Structures using Gray-scale Lithography and Deep Reactive Ion Etching," Sensors and Actuators A: Physical, Vol. 119, pp. 245-253, 2005. B. Morgan, C.M. Waits, and R. Ghodssi, "Compensated Aspect Ratio Dependent Etching (CARDE) using Gray-scale Technology," Microelectronic Engineering, Vol. 77, Issue 1, pp. 85-94, January 2005. B. Morgan, C.M. Waits, J. Krizmanic  and R. Ghodssi, "Development of a Deep Silicon Phase Fresnel lens using Gray-scale Technology and Deep Reactive Ion Etching," Journal of Microelectromechanical Systems (JMEMS), Vol. 13, pp. 113-120, 2004. C. M. Waits, A. Modafe  and R. Ghodssi, "Investigation of Gray-scale Technology for Large Area 3-D Silicon MEMS Structures," Journal of Micromechanics and Microengineering (JMM), Vol. 13, pp. 170-177, 2003.    Conference Papers L. A. Mosher, C. M. Waits, B. Morgan, and R. Ghodssi, "A New Paradigm for High Resolution 3D Lithography," Proceedings of the 21st IEEE International Conference on Micro Electro Mechanical Systems (MEMS 2008), pp. 395-398, Tucson, AZ, USA, January 13-17, 2008. L. A. Mosher, B. C. Morgan, and R. Ghodssi, "Double-Exposure Gray-Scale Technology for Improved Vertical Resolution of 3D Photoresist Structures," American Vacuum Society 54th International Symposium, Seattle, WA, October 14 - 19, 2007. B. Morgan and R. Ghodssi, "Compact Tunable Resonators using Vertically-shaped Comb-fingers Towards Vibration Energy Scavenging," Sixth International Workshop on Micro and Nanotechnology for Power Generation and Energy Conversion Applications (Power MEMS '06), pp. 177-180, Berkeley, CA, USA, November 29-December 1, 2006. L. Mosher, B. Morgan, C. M. Waits and R. Ghodssi, "Advanced Techniques in 3D Photolithography for MEMS," 25th Army Science Conference, Orlando, FL, USA, November 27-30, 2006. R. Ghodssi, "Gray-scale Technology for 3-D Static and Dynamic MEMS," AVS 53rd International Symposium, San Francisco, CA, USA, November 12-17, 2006 (Invited). B. Morgan and R. Ghodssi, "Automated optical fiber alignment in 2-axes usig 3-D shaped actuators," Proceedings of the Solid State Sensor, Actuator, and Microsystems Workshop (Hilton Head 2006), pp. 70-73, Hilton Head Island, SC, USA, June 4-8, 2006. B. Morgan and R. Ghodssi, "On-Chip 2-Axis Optical Fiber Actuator Using Gray-Scale Technology," 19th International Conference on Micro Electro Mechanical Systems (MEMS 2006), pp. 266-269, Istanbul, Turkey, January 22-26, 2006. B. Morgan and R. Ghodssi, "On-Chip 2-Axis Optical Fiber Actuator Using Gray-Scale Technology," International Semiconductor Device Research Symposium 2005 (ISDRS 2005), Bethesda, MD, December 7-9, 2005. J. Krizmanic, R. Streitmatter, N. Gehrels, K. Gendreau, Z. Arzoumanian, R. Ghodssi, B. Morgan, and G. Skinner, "Development of Ground-testable Phase Fresnel Lenses in Silicon," Gamma Wave Workshop on Focusing Telescopes in Nuclear Astrophysics, Espace St. Jacques, Bonifacio, Corsica, September 12-15, 2005. R. Ghodssi, B. Morgan, and C.M. Waits, "Variable Height Precision DRIE Technology," Power and Energy Collaborative Technology Alliance (CTA) Four-year Review, Hyatt Regency, Crystal City, Arlington, VA, June 1-3, 2005. B. Morgan and R. Ghodssi, "Biasing Gray-scale Lithography for Integration with Deep Reactive Ion Etching (DRIE)," 49th International Conference on Electron, Ion, and Photon Beam Technology & Nanofabrication, Grande Lakes, Florida, May 31 - June 3, 2005. B. Morgan and R. Ghodssi, "Design and Simulation of Comb-drive Actuators Incorporating Gray-scale Technology for Tailored Actuation Characteristics," Proceedings of the SPIE Microtechnologies for the New Millennium 2005, Volume 5836, pp. 468-476, Seville, Spain, May 9-11, 2005 (Invited). B. Morgan, C.M. Waits, and R. Ghodssi, "MEMS-based Gray-scale Technology for Large Area  3-D Structures in Silicon," IVC16, The 16th International Vacuum Congress, Venice, Italy, June 28 - July 2, 2004. B. Morgan, C.M. Waits and R. Ghodssi, "Development and Integration of a 3D Silicon MEMS Technology Using Gray-Scale Lithography and Deep Reactive Ion Etching," 2004 Solid-State Sensor, Actuator and Microsystems Workshop, Open Poster Session, Hilton Head Island, SC, June 6-10, 2004. R. Ghodssi, C.M. Waits and B. Morgan, "Development and Optimization of Integrative MEMS-based Gray-scale technology in Silicon for Power MEMS Applications," Proceedings of the Collaborative Technology Alliance (CTA) Conference, Marriott Wardman Park Hotel, Washington D.C., May 6, 2004 (Invited). B. Morgan, C.M. Waits, J. Krizmanic and R. Ghodssi, "Development of a Deep Phase Fresnel Lens in Silicon," American Vacuum Society 50th International Symposium, Baltimore, MD, November 2-7, 2003. R. Ghodssi, C. M. Waits, B. C. Morgan and M. J. Kastantin, "Gray-Scale MEMS Technology for Power MEMS Silicon Devices," Proceedings of the Collaborative Technology Alliance (CTA) Annual Symposium, P&E Technical Session, Inn and Conference Center, University of Maryland, pp. 55-59, April 29 - May 1, 2003 (Invited). C. M. Waits, A. Modafe and R. Ghodssi, "MEMS-based Gray-scale Technology," American Vacuum Society 49th International Symposium, Denver, Colorado, November 3-8, 2002. C. M. Waits, A. Modafe and R. Ghodssi, "MEMS-based Gray-scale Lithography," 2002 Solid State Sensor, Actuator and Microsystems Workshop, Open Poster Session, Hilton Head Island, South Carolina, June 2-6, 2002. C. M. Waits, R. Ghodssi, M. H. Ervin and M. Dubey, "MEMS-based Gray-scale Lithography,"  Proceedings of the 2001 International Semiconductor Device Research Symposium (ISDRS), Washington D.C., pp. 182-85, December 5-7, 2001.    Other Publications B. Morgan and R. Ghodssi, "Aligning Optical Fibers by Means of Actuated MEMS Wedges," NASA Tech Briefs/Photonics Tech Briefs, Vol. 31, No. 1, p.15A, Jan 2007.