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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple style='word-wrap: break-word;-webkit-nbsp-mode: space;-webkit-line-break: after-white-space'><div class=WordSection1><div><p class=MsoNormal><span style='font-size:10.5pt;font-family:"Calibri","sans-serif";color:black'><o:p> </o:p></span></p></div><div><p style='margin:0in;margin-bottom:.0001pt'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#262626'>Prof. John C. “Jack” Wolfe<o:p></o:p></span></p><p style='margin:0in;margin-bottom:.0001pt'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#262626'>Hugh Roy and Lillie Cranz Cullen Distinguished University Professor,<o:p></o:p></span></p><p style='margin:0in;margin-bottom:.0001pt'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#262626'>Dept. of Electrical and Computer Engineering; Professor of Physics<o:p></o:p></span></p><p style='margin:0in;margin-bottom:.0001pt'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#262626'>_______________________________________________________________________<o:p></o:p></span></p><p style='margin:0in;margin-bottom:.0001pt'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#262626'>FRIDAY, JUNE 24, 2011<o:p></o:p></span></p><p style='margin:0in;margin-bottom:.0001pt'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#262626'>University of Houston Science Center, Room 102<o:p></o:p></span></p><p style='margin:0in;margin-bottom:.0001pt'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#262626'>12:00 Noon – 1:00 p.m.<o:p></o:p></span></p><p style='margin:0in;margin-bottom:.0001pt'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p style='margin:0in;margin-bottom:.0001pt'><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#262626'>“Image Noise in Helium Lithography”<o:p></o:p></span></b></p><p style='margin:0in;margin-bottom:.0001pt'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p style='margin:0in;margin-bottom:.0001pt'><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#262626'>Synopsis</span></b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#262626'>: In the 1990’s “nanotechnofabrication” meant building structures with spatial dimensions below 100 nm<o:p></o:p></span></p><p style='margin:0in;margin-bottom:.0001pt'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#262626'>(30-50 nm was readily attainable in this timeframe). Today, however, sub-10 nm structures are required for many<o:p></o:p></span></p><p style='margin:0in;margin-bottom:.0001pt'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#262626'>applications, including the fabrication of integrated circuits, magnetic storage media, graphene nanoribbons, and<o:p></o:p></span></p><p style='margin:0in;margin-bottom:.0001pt'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#262626'>pinning center arrays. This talk describes image noise, one of the principal challenges to emerge as lithographic<o:p></o:p></span></p><p style='margin:0in;margin-bottom:.0001pt'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#262626'>technology advances from ~100 nm to the sub-10 nm domain.<o:p></o:p></span></p><p style='margin:0in;margin-bottom:.0001pt'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p style='margin:0in;margin-bottom:.0001pt'><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#262626'>Abstract</span></b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#262626'>: A distinctive feature of resist exposure by energetic helium ions or neutral atoms is that critical exposure<o:p></o:p></span></p><p style='margin:0in;margin-bottom:.0001pt'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#262626'>densities are very low, about 100 times smaller than for electrons. Thus, particle distributions are sparse, leading to<o:p></o:p></span></p><p style='margin:0in;margin-bottom:.0001pt'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#262626'>significant statistical fluctuations in the deposited energy density even in Polymethylmethacrylate (PMMA), a<o:p></o:p></span></p><p style='margin:0in;margin-bottom:.0001pt'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#262626'>relatively insensitive, non-chemically amplified resist. The impact is first seen as roughness in the region of partial<o:p></o:p></span></p><p style='margin:0in;margin-bottom:.0001pt'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#262626'>exposure on a feature’s edge where the bunching of just a few particles may cause the energy density to shift<o:p></o:p></span></p><p style='margin:0in;margin-bottom:.0001pt'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#262626'>above or below the resist development threshold. As feature size is reduced, however, fluctuations in the total<o:p></o:p></span></p><p style='margin:0in;margin-bottom:.0001pt'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#262626'>number of particles (shot noise) become larger as a fraction of average dose, potentially causing over and under<o:p></o:p></span></p><p style='margin:0in;margin-bottom:.0001pt'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#262626'>exposure of the entire feature. This talk presents an integrated study of image noise in helium lithography that<o:p></o:p></span></p><p style='margin:0in;margin-bottom:.0001pt'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#262626'>compares shape variations in neutral particle mask images with the predictions of a Monte-Carlo model. The model<o:p></o:p></span></p><p style='margin:0in;margin-bottom:.0001pt'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#262626'>accounts for the following: 1) Poisson statistics of the particle emission process, 2) the variable spatial distribution of<o:p></o:p></span></p><p style='margin:0in;margin-bottom:.0001pt'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#262626'>the particles within the aerial image, 3) the effect of scattering on the particle distribution at various depths in the<o:p></o:p></span></p><p style='margin:0in;margin-bottom:.0001pt'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#262626'>resist, and 4) smoothing of the deposited energy distribution by exposure and development processes. Proximity<o:p></o:p></span></p><p style='margin:0in;margin-bottom:.0001pt'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#262626'>lithography experiments were carried out using 10 keV neutral helium atoms in 20 nm thick PMMA resist under<o:p></o:p></span></p><p style='margin:0in;margin-bottom:.0001pt'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#262626'>conditions of 12.7 nm [FWHM] penumbral image blur. The energy smoothing function is assumed, based on previous<o:p></o:p></span></p><p style='margin:0in;margin-bottom:.0001pt'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#262626'>experiments, to be Gaussian and its standard deviation s treated as a free parameter. Model predictions of the<o:p></o:p></span></p><p style='margin:0in;margin-bottom:.0001pt'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#262626'>power spectral density of line edge roughness agree with experiment for ó =5.0 ± 0.5 nm. The model predicts that<o:p></o:p></span></p><p style='margin:0in;margin-bottom:.0001pt'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#262626'>using a resist with a critical dose 20 times higher than PMMA and reducing penumbra to 0.5 nm [FWHM], for<o:p></o:p></span></p><p style='margin:0in;margin-bottom:.0001pt'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#262626'>example by reducing the proximity gap, would reduce shape fluctuations to less than 0.5 nm [FWHM] for dense 10<o:p></o:p></span></p><p style='margin:0in;margin-bottom:.0001pt'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#262626'>nm dot arrays.<o:p></o:p></span></p><p style='margin:0in;margin-bottom:.0001pt'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p style='margin:0in;margin-bottom:.0001pt'><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#262626'>Biographical Sketch</span></b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#262626'>: Jack Wolfe earned his B.S. and Ph.D. degrees in Physics at the University of Rochester. He joined the ECE</span><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> </span><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#262626'>department at UH in 1976. His work over the past 3 decades has focused on development of nanofabrication technology for</span><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> </span><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#262626'>applications in data storage, integrated circuit manufacturing, and energy. He served as Program Chair of the 1999 International</span><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> </span><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#262626'>Symposium on Electron, Ion, and Photon Beam Technology and Nanofabrication, the preeminent conference on lithography and</span><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> n</span><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#262626'>anofabrication. He has served as Department Chair of ECE, Interim Dean of the College of Engineering, and Interim Department</span><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> </span><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#262626'>Chair of ECE. He holds the position of Hugh Roy and Lillie Cranz Cullen Distinguished University Professor. He holds a joint</span><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> </span><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#262626'>appointment in the Physics Department where he plans to become involved in curriculum development.</span><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p></o:p></span></p><p style='margin:0in;margin-bottom:.0001pt'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p style='margin:0in;margin-bottom:.0001pt'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#262626'>Persons with disabilities who require special accommodations in<o:p></o:p></span></p><p style='margin:0in;margin-bottom:.0001pt'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#262626'>attending this lecture should call (713) 743-8210 as soon as possible.<o:p></o:p></span></p></div><div><div><div><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:black'><o:p> </o:p></span></p></div></div></div></div></body></html>